retina , vitrous opto

Question 1

shining a small spot of light onto the center of the receptive field of a retinal ganglion cell results in an increased frequency of action potentials; however, increasing the size of the light causes a decrease in the frequency of action potentials. Why does this occur?

The retinal dark current, if overly exposed, results in spatial antagonism by cone cells

Correct answer Due to the fact that ganglion cells have receptive fields that are center-surround

Rhodopsin responds preferentially to small sources of light allowing for high spatial resolution

Because activation of rods causes the inhibition of ganglion cells

Answer 1

The majority of ganglion cells possess center-surround receptive fields and therefore exhibit lateral inhibition. This property serves to increase spatial resolution. The receptive fields can be either center on or center off. The receptive field appears like a donut, with the center being excited by light and the surrounding annulus inhibited by light or vice versa. Increasing the size of the stimulus causes summation of both parts of the receptive fields, resulting in a greater reduction in the frequency of action potentials than if the center were to be stimulated alone.

Question 2

Which of the following juvenile onset macular diseases results in the development of a macular lesion consisting of an accumulation of lipofuscin within the retinal pigment epithelium?

Juvenile retinoschisis

Fundus flavimaculatus

Familial-dominant drusen

Correct answer Best vitelliform macular dystrophy

Stargardt disease

Answer 2

Best vitelliform macular dystrophy

Juvenile Best disease, or vitelliform macular dystrophy, is a rare hereditary macular disease (autosomal dominant with variable penetrance) that typically presents in childhood or early adulthood. The progression of Best disease is very characteristic, as the appearance of the vitelliform lesions are classically grouped into 5 stages:

• Stage 0 (pre-vitelliform): Children in this stage are usually asymptomatic and possess a normal fundus appearance; an electrooculogram (EOG) performed in this stage will reveal a subnormal result
• Stage 1: Patients will begin to develop pigmentary mottling in the area of the macula
• Stage 2 (vitelliform): This stage commonly begins in early childhood and typically does not impair visual acuity; the classic “sunny-side up” egg yolk appearance in the area of the macula develops due to an accumulation of lipofuscin within the retinal pigment epithelium
• Stage 3 (pseudo-hypopyon): This stage usually occurs near puberty in which part of the macular lesion becomes absorbed; over time, absorption may continue, and the entire lesion can become completely absorbed with minimal effect on vision
• Stage 4 (vitelliruptive): Fundus examination in this stage will reveal the classic “scrambled egg” appearance in which the vitelliform lesion begins to break up; visual acuity typically begins to drop as patients may develop fibrous scarring in the macular region, geographic atrophy, or a choroidal neovascular membrane (this usually occurs around the fifth decade)

Question 3

Which of the following BEST describes the location of the fovea with respect to the center optic disc?

4mm nasal and 0.8mm inferior

4mm nasal and 0.8mm superior

4mm temporal and 0.8mm superior

Correct answer 4mm temporal and 0.8mm inferior

Answer 3

4mm temporal and 0.8mm inferior
The macula is a circular area that is approximately 5-6mm in diameter, centered at the fovea, which itself is about 1.5 to 2.0mm in size. Anatomically, the macula is defined as the region of the retina in which there are 2 or more layers of ganglion cells present; the fovea rests at the center of this area. The fovea is considered to lie approximately 4mm temporally and 0.8mm inferiorly to the center of the optic disc.

Question 4

Which of the following refractive errors has a higher correlation with the development of a posterior vitreal detachment (PVD)?

Astigmatism

Emmetropia

Anisometropic hyperopia

Correct answer Myopia

Hyperopia

Answer 4

Syneresis and liquification of the vitreous are part of the normal aging process, but they also may cause a posterior vitreal detachment. PVDs occur with an earlier onset if something speeds up the process of vitreal aging. These conditions include myopia, trauma, diabetes, intraocular surgery, intraocular inflammation, and vitreal hemorrhages.

Question 5

A patient presents to your office with complaints of severely decreased visual acuity and flashes of light that appeared suddenly. Upon dilated retinal evaluation, you observe a retinal detachment that has affected the macula. In which of the following quadrants are you MOST likely to observe the offending retinal break?

Inferior-nasal

Inferior-temporal

Superior-nasal

Correct answer Superior-tempora

Answer 5

Retinal breaks leading to the formation of retinal detachments are most commonly found in the superior-temporal region, especially in cases of total retinal detachments or those affecting the macula, due to the nature of gravitational forces. Superior-nasal tears are the next most commonly observed. Additionally, the most likely cause of a retinal detachment is vitreoretinal traction at the attachment of the vitreous base, which leads to a retinal tear as the vitreous detaches from this area; fluid then enters the subretinal space at the site of the tear, resulting in a detachment of the retina.

The patient history may also provide a clue to the location of the break. When detachments progress rather quickly, the break is usually large and found superiorly closer to the equator than to the ora. Small, inferior, or extremely peripheral tears usually result in much slower progression. The quadrant of visual field loss that is first detected is also valuable in locating the primary retinal break.

Question 6

The deflection of retinal veins at arteriovenous crossings that occurs in association with hypertensive retinopathy is known as which of the following signs?

Correct answer Salus’ sign

Seidel sign

Bonnet sign

Gunn sign

Answer 6

Salus’ sign is a clinical indication of hypertensive retinopathy that is characterized by the deflection of retinal veins at arteriovenous crossings. The presence of this sign indicates Grade 2 hypertensive retinopathy.

Bonnet sign involves the funduscopic observation of the banking of veins distal to the site of arteriovenous crossings, while Gunn sign is characterized by tapering of veins occurring on either side of the crossings. Both Bonnet and Gunn signs are clinical findings associated with Grade 3 hypertensive retinopathy.

Question 7

You wish to examine the nerve fiber layer of a patient while using the direct ophthalmoscope. Which filter will serve to enhance your views and any possible nerve fiber layer defects?

No filter yields the most accurate assessment

Cobalt blue

Correct answer Red-free

Yellow

Answer 7

The red-free filter serves to enhance the assessment of the nerve fiber layer, choroidal lesions, and retinal vasculature.

The yellow filter helps to protect the ocular structures by blocking infrared and UV light.

The cobalt blue filter, used in conjunction with sodium fluorescein, is useful for the evaluation of the integrity of the cornea.

Question 8

How many photons are necessary to stimulate a rod cell?

10 photons

50 photons

100 photons

1 photon

Answer 8

1 photon
One photon is all that is required to stimulate a rod cell. The photon is absorbed by rhodopsin located in the disc membrane of the outer segment causing a cascade of events. However, in order for a stimulus to be detected, around 10 photons must be experienced. This is can occur either by spatial summation or by temporal summation.

Question 9

Your 67 year-old male patient presents with flame-shaped and dot-blot hemorrhages in the inferior retina of his left eye secondary to a branch retinal vein occlusion. Which of the following statements best describes the MOST common etiology of this ocular condition?

Significantly elevated intraocular pressure leading to compression of a retinal vein and subsequent venous occlusion

Intimal thickening of a vein resulting in progressive narrowing of the central lumen and eventual venous occlusion

A migrating emboli, most commonly from an atheromatous plaque, becomes lodged at a vessel bifurcation, leading to the occlusion of a retinal vein

Correct answer Thickening of an overlying retinal arteriole compressing the vein, resulting in a focal venous occlusion

Answer 9

Retinal venous occlusive diseases (such as branch retinal vein occlusions and central retinal vein occlusions) have an important association with arteriosclerotic disease. Retinal arterioles and their corresponding retinal veins share a common adventitial sheath at arteriovenous crossings. It is because of this characteristic that when a retinal artery becomes hardened and thickened as a result of arteriosclerosis, significant compression on the adjacent retinal vein can occur. Progressive and prolonged venous compression also causes changes in the retinal veins, which includes loss of venous endothelial cells and thrombus formation. Eventually, the artery will compress the vein enough that this, in conjunction with the other associated microvascular changes, will result in occlusion of the retinal vein leading to a central, or more commonly, branch retinal vein occlusion.

Elevated intraocular pressure can also cause a venous occlusion; however, this most commonly results as a central retinal vein occlusion wherein the site of occlusion involves the edge of the optic cup.

Question 10

The uveal tract is comprised of which three structures?

The choroid, the retina and the episclera

The iris, ciliary body and the choroid

The ciliary body, the lens and the retina

The iris, the retina and the optic nerve

The optic nerve, the lens and the episclera

Answer 10

The iris, ciliary body and the choroid

Question 11

Which of the following statements BEST describes the underlying etiology of the characteristic “cherry-red spot” observed in patients with a central retinal artery occlusion?

Choroidal neovascular membrane underlying the macula

Intact macular circulation through a cilioretinal artery

Intact choroidal circulation in contrast to pale surrounding retina

Intraretinal macular hemorrhages

Vitreous hemorrhaging in the macular region

Answer 11

Intact choroidal circulation in contrast to pale surrounding retina

A characteristic observation associated with the development of a central retinal artery occlusion is the presence of a “cherry red spot” at the region of the macula. This retinal finding typically manifests several hours after the artery obstruction and usually gradually subsides in the following weeks. The appearance of the bright red central spot is due to the fact that the macular region is supplied with blood from the underlying choroid, which remains unaffected in a central retinal artery occlusion because it is supplied by the posterior ciliary arteries. This macular area particularly stands out against the surrounding pale retina that is ischemic as a result of the occlusion.

Question 12

The presence of which of the following retinal characteristics will result in a corresponding area of hyperfluorescence during fluorescein angiography?

Congenital hypertrophy of the RPE

Choroidal nevus

Pigment epithelial detachment

Intraretinal hemorrhage

Lipofuscin

Hard exudates

Answer 12

Pigment epithelial detachment

Areas of hyperfluorescence that appear during fluorescein angiography occur due to either an absolute increase in the amount of fluorescein in the retinal tissues or as a result of enhanced visualization of a normal quantity of fluorescein in the fundus. Conditions that can lead to hyperfluorescence include leakage of dye from abnormal choroidal vasculature (such as a choroidal neovascular membrane), abnormal retinal neovascularization (as in proliferative diabetic retinopathy), or breakdown of the inner blood-retinal barrier (cystoid macular edema). Hyperflourescence also occurs as a result of pooling of fluorescein secondary to breakdown of the outer blood-retinal barrier in such conditions as central serous retinopathy and pigment epithelial detachments. A transmission (or window) defect caused by an absence or atrophy of the RPE results in unmasking of normal background choroidal fluorescence, leading to the appearance of hyperfluorescent areas.

Hypofluorescent regions on fluorescein angiography are due to either obstruction (masking) of normal density of fluorescein in the retinal tissue (blood, hard exudates, increased density of RPE, or choroidal nevi) or inadequate perfusion of the retinal tissue (vascular occlusion, or loss of the vascular bed).

Question 13

The phenomenon, sometimes called tobacco dust, in which pigment is visible in the vitreal chamber and is fairly pathognomonic for a retinal tear is known as which of the following?

Ascension phenomenon

Photopsia

Cloquet’s canal

Correct answer Schafer’s sign

Answer 13

Schafer’s sign occurs when there is a release of pigment into the vitreal chamber. The excessive pigment may be noted by the patient as a sudden increase in floaters. This sign usually indicates the presence of a retinal tear because a break in the retina may release retinal pigment epithelium. Pigment in the vitreal chamber may also be associated with a posterior uveitis or trauma or can occur secondary to intraocular surgery. It is of vital importance when a patient enters your clinic complaining of a recent increase in floaters, especially monocularly, or if you visualize pigment in the vitreous, that you rule out a retinal tear. Remember, many patients who suffer from a retinal tear are asymptomatic.

The ascension phenomenon describes the ability of the practitioner to better visualize vitreal cells or other suspended granules by asking the patient to move their eyes rapidly and then upon stabilization, using the slit lamp, the doctor waits and watches for cells or other details to move across the viewing beam.

Photopsias are flashes of light that may be perceived by the patient during periods of retinal traction.

Cloquet’s canal is comprised of the primary vitreous, which develops from weeks 3 through 9. The secondary vitreous then begins to form and condenses the primary vitreous, producing Cloquet’s canal.

Question 14

You are examining the right peripheral retina of your patient with a retinal detachment in order to locate the primary location of a retinal break. You observe that the detachment of the retina is inferior, and that the subretinal fluid is slightly higher on the temporal side. In which location do you MOST likely expect to find the break?

Temporally at 9 o’clock

Inferior nasally

Correct answer Inferior temporally

Nasally at 3 o’clock

Inferior at 6 o’clock

Answer 14

he configuration of subretinal fluid in cases of a rhegmatogenous retinal detachment is relevant in that it is determined by gravitational forces, the anatomical limits of the eye (ora serrata and optic nerve), and the location of the primary retinal break. Therefore, the conformation of the retinal detachment can aid in determining the suspected location for the offending retinal break, if it is not initially observed. For example, if the retinal break occurs superiorly, the subretinal fluid will first migrate inferiorly on the same side as the break and then will eventually spread superiorly on the opposite side. In the case of the above patient, when the retinal detachment is inferior and the subretinal fluid is higher on one side; therefore, the site of the retinal break is likely to be located inferiorly on that same side.

Question 15

ou decide to perform fluorescein angiography on a patient with decreased vision and central metamorphopsia in his left eye. Results show a “smoke-stack” appearance in which fluorescein enters the subretinal space, ascends vertically, then spreads laterally. Which of the following retinal conditions is your patient MOST likely suffering from?

Cystoid macular edema

Choroidal neovascular membrane

Central serous retinopathy

Pigment epithelial detachment

Answer 15

Central serous Fluorescein angiography studies of patients with central serous retinopathy typically reveal a classic “smoke-stack” presentation. This appearance is a result of leakage of fluorescein dye through the retinal pigment epithelium, which causes a small hyperfluorescent spot in the early stage of angiography. During the later venous stage, dye will continue to pass into the subretinal space, where it ascends vertically to the upper limit of the detachment before extending laterally until the entire subretinal space is filled with fluorescein.

Patients with cystoid macular edema will reveal a “flower-petal” pattern of hyperfluorescence on fluorescein angiography studies. This is caused by the accumulation of the fluorescein dye inside the microcystic spaces that have developed within the retina.

Classic choroidal neovascular membranes will show a well-defined membrane that fills with fluorescein in the early phase, creating a lacy appearance. The dye will then eventually leak after 1-2 minutes into the subretinal space surrounding the neovascular membrane.

Question 16

ou wish to evaluate the ora serrata of your patient’s retina using a Goldmann 3-mirror. Which mirror will allow for the MOST extensive evaluation of the ora serrata?

Correct answer The bullet mirror (angled at 59 degrees from the corneal plane)

You can only evaluate the ora serrata using binocular indirect ophthalmoscopy

The trapezoidal mirror (angled at 73 degrees from the corneal plane)

The square mirror (angled at 67 degrees from the corneal plane)

Answer 16

The bullet mirror (angled at 59 degrees from the corneal plane)

The center contact lens is used to visualize the structures of the posterior pole. The bullet mirror (angled at 59 degrees from the corneal plane) is used to assess the ora serrata (although sometimes difficult in some patients) and the structure of the anterior chamber angle. The square mirror (angled at 67 degrees from the corneal plane) may be used to investigate the area between anterior equatorial retina and the ora serrata. Lastly, the trapezoidal mirror (angled at 73 degrees from the corneal plane) is used at evaluate the retinal equatorial region.

Question 17

The rhodopsin molecule is found at which location in a rod photoreceptor?

The membrane of the inner segment

Spherule

The membrane of the outer segment

Nucleus

Answer 17

The membrane of the outer segment

Rhodopsin is embedded in the discs of the outer segment of the rod and absorbs a photon of light, causing an electrical change in the membrane of the rod. It is necessary for several rods to summate in order to signal the presence of a stimulus. Rods then release glutamate post-synaptically to bipolar and horizontal cells.

Question 18

Which lamina of the choroid does NOT contain melanocytes?

Choriocapillaris

Sattler’s layer

Suprachoroid

Haller’s layer

Answer 18

Choriocapillaris

The suprachoroid is the outermost layer of the choroid and serves as a transition junction between the sclera and the choroid. The suprachoroid is comprised mostly of 10-15 layers of collagen which bind to the lamina fusca of the sclera. Many melanocytes and fibroblasts are located in this layer.

Haller’s layer and Sattler’s layer together form the vessel layer or the stroma. This layer is largely comprised of blood vessels. Haller’s layer lays external to Sattler’s layer and contains larger vessels (one way to remember the caliber of the vessels is that the ‘ll’ in Haller matches the ‘l’ in large). Sattler’s layer is characterized by smaller blood vessels (the ‘S’ in Sattler matches the ‘s’ in small). In general, the diameter of the blood vessels becomes smaller as one proceeds from the outer edge to the inner edge of the stroma. The stroma appears brown in color due to the presence of melanocytes.

The choriocapillaris is located internally to the stroma. This layer is characteristic of a network of capillaries that serve to maintain the outer retina. The capillaries in the choroid differ from those of the rest of the body in that they are slightly wider and allow the passage of several blood cells at a time, whereas those of the body are narrower and only allow blood cells to pass one by one in a linear fashion. Choriocapillaris does not contain melanocytes.

Question 19

What is the correct order of the choroidal lamina from most external to most internal?

Choriocapillaris-> Stroma (vessel layer)-> Suprachoroid-> Bruch’s membrane

Suprachoroid-> Stroma (vessel layer)-> Choriocapillaris-> Bruch’s membrane

Stroma (vessel layer)-> Suprachoroid-> Bruch’s membrane-> Choriocapillaris

Suprachoroid-> Bruch’s membrane-> Choriocapillaris-> Stroma (vessel layer)

Answer 19

Suprachoroid-> Stroma (vessel layer)-> Choriocapillaris-> Bruch’s membrane
The correct order of the choroidal lamina from the most external to most internal is the suprachoroid followed by the stroma (or the vessel layer) which is succeeded by choriocapillaris and lastly Bruch’s membrane.

The suprachoroid is the outermost layer of the choroid and serves as a transition junction between the sclera and the choroid. The suprachoroid is comprised mostly of 10-15 layers of collagen which bind to the lamina fusca of the sclera. Many melanocytes and fibroblasts are located in this layer.

Haller’s layer and Sattler’s layer together form the vessel layer or the stroma. This layer is largely comprised of blood vessels. Haller’s layer lays external to Sattler’s layer and contains larger vessels (one way to remember the caliber of the vessels is that the ‘ll’ in Haller matches the ‘l’ in large). Sattler’s layer is characteristic of smaller blood vessels (the ‘S’ in Sattler matches the ‘s’ in small). In general, the diameter of the blood vessels becomes smaller as one proceeds from the outer to the inner edge of the stroma. The stroma appears brown in color due to the presence of melanocytes.

The choriocapillaris is located internally to the stroma. This layer is characteristic of a network of capillaries that serve to maintain the outer retina. The capillaries in the choroid differ from those of the rest of the body in that they are slightly wider and allow the passage of several blood cells whereas those of the body are narrower allowing for blood cells to pass one by one in a linear fashion. Choriocapillaris does not contain melanocytes.

Bruch’s membrane lies between the choriocapillaris of the choroid and the retinal pigment epithelium of the retina. Although this membrane is very thin (about 2 microns thick) it is very complex. The membrane consists of five facets. The outermost component is the basement membrane of the choriocapillaris which is followed by the outer collagenous zone, the elastic layer, the inner collagenous zone and most internally the basement membrane of the retinal pigment epithelium.

Question 20

Which of the following wavelengths of visible light has an increased association with the development of macular degeneration?

485nm-510nm

570nm-620nm

Correct answer 415nm-455nm

520nm-555nm

Answer 20

Recent studies have demonstrated a correlation between blue-violet light that lies within the range of 415nm-455nm and the development of macular degeneration. Excessive exposure to light that falls within this bandwidth is associated with death of the retinal pigment epithelial cells. However, blue-turquoise light (465-495nm) does not appear to possess detrimental effects to ocular health. Blue-turquoise light is important in activation of the pupillary reflex as well as management of the circadian sleep/wake cycle. There is increasing evidence that compact fluorescent lamps, LED lights as well as sunlight all transmit blue-violet light, which over time may be linked with retinal damage.

Question 21

Which of the following types of tumors represents the MOST common primary intraocular malignancy of childhood?

Choroidal hemangioma

Retinoblastoma

Choroidal melanoma

Astrocytoma

Intraocular lymphoma

Answer 21

Retinoblastoma

Retinoblastoma is the most common primary intraocular malignancy in children. It represents about 3-4% of all childhood cancers, occurring in about 1 in 17,000 live births. About 80% of all children diagnosed with retinoblastoma present with the condition before the age of 3, and an initial diagnosis over the age of 6 is extremely rare. Melanoma is the most common intraocular malignancy in adults.

Question 22

Which of the following 3 conditions are associated with a higher incidence of developing a posterior vitreal detachment? (Select 3)

Anisometropic hyperopia

Keratoconus

Diabetes

High Myopia

Intraocular surgery

Hypertension

Answer 22

Correct answer Diabetes

Correct answer High Myopia

Correct answer Intraocular surgery

Syneresis and liquification of the vitreous are part of the normal aging process, but they also may cause a posterior vitreal detachment (PVD). PVDs can occur earlier in one’s life if something speeds up the process of vitreal aging. These conditions may include myopia, trauma, diabetes, intraocular surgery, intraocular inflammation, and vitreal hemorrhages.

Question 23

Which of the following blood vessels offers the greatest resistance and the lowest flow rate?

Choroidal vessels

Ophthalmic artery

Carotid artery

Correct answer Retinal vessels

Answer 23

Blood vessels of the retina are very small and as such offer high resistance and low flow rate (about 1.7 ml/min/gm) due to their small lumen. In contrast, choroidal vessels are larger and have lower resistance and a higher flow rate (roughly 19/ml/min/gm). The ophthalmic and carotid arteries are even larger than the retinal and choroidal vessels leading to even higher flow rates.

Question 24

While performing binocular indirect ophthalmoscopy (BIO), you notice a retinal nevus as you are viewing the temporal aspect of a patient’s retina. The nevus is displaced towards the left portion of your condensing lens (YOUR left). How should you maneuver in order to center the image of the nevus in your lens?

Pivot yourself to your left and move the lens to your right

Correct answer Pivot yourself and the lens towards your left

Pivot yourself to your right and move the lens to your left

Pivot yourself and the lens towards your right

Answer 24

If you wish to center an image in your condensing lens, you must move as a unit (you and the lens both move together) towards the image or structure that you wish to view.

Question 25

Retinopathy of prematurity is a developmental disorder of the retina that occurs due to exposure to which of the following in premature infants?

Adenovirus

High lead levels

Retrovirus

High mercury levels

Correct answer High oxygen concentration

Answer 25

Retinopathy of prematurity (also known as retrolental fibroplasia) occurs when premature infants are exposed to high oxygen concentrations which cause vasoconstriction of immature peripheral retinal blood vessels. Subsequent removal of oxygen leads to a hypoxic state in the retinal periphery and subsequent proliferation of new blood vessels that have poor endothelial junctions and are leaky. This in turn leads to neovascular invasion into the vitreous, development of vitreoretinal adhesions, and subsequent hemorrhage and retinal detachment.

Question 26

Which of the following structures is NOT found in cones?

A synaptic terminal

Mitochondria

An inner segment

Correct answer Free-floating discs in the outer segment

Ciliary process a.k.a. cilium

Answer 26

Free-floating discs in the outer segment

Cones and rods possess outer segments which consist of stacks of disc-like structures containing photopigment however, the discs of cones are not free-floating. The discs of cones remain attached as they migrate outwards. It was previously thought that only rods possessed a cilium but this has been proven to be inaccurate. Both rods and cones possess ciliary processes, inner segments, mitochondria and synaptic terminals. The synaptic terminals of rods differ in their morphology from cones in that they are slightly smaller and rounder and are called spherules while cones display a larger and flatter terminal called a pedicle.

Question 27

Midget ganglion cells receive information pre-synaptically from which cells?

Rod bipolar cells

Midget bipolar cells

Horizontal bipolar cells

Flat bipolar cells

Answer 27

Midget bipolar cells

Midget bipolar cells synapse onto midget ganglion cells. These are very selective and exclusive channels as one cone cell synapses with one midget bipolar cell which then in turn relays the information to a midget ganglion cell. There is no additional input from other cells or synapses. These types of monosynaptic cells are most common in the central retina thus explaining the ability to visually discern fine details.

Flat bipolar cells receive information from many cone cells and in turn synapse with many ganglion cells.

Rod bipolar cells, as their name suggests, convey information from many rod cells to several ganglion cells. Rods relay information only to rod bipolar cells.

Question 28

What is the name of the funnel-shaped region anterior to the optic disc that represents the posterior termination of Cloquet’s canal?

Correct answer Area of Martegiani

Berger’s space

Hyaloid space

Patellar fossa

Erggelet’s space

Answer 28

The area of Martegiani signifies the funnel-shaped dilation surrounding the optic disc representing the posterior termination of Cloquet’s canal (also known as the hyaloid canal).

Berger’s space is an area between that anterior face of the vitreous body and the posterior lens capsule. It represents the anterior termination of Cloquet’s canal. It is also known as Erggelet’s space.

The patellar fossa characterizes the anterior depression of the vitreous body in which the crystalline lens resides.

Question 29

Upon examining your 51 year-old male patient, you observe what appears to be a subtle retinal nerve fiber layer defect. Which of the following colored filters will allow for enhanced visualization of this tissue?

Blue

Red

Correct answer Green

Yellow

Answer 29

Localized damage to the retinal nerve fiber layer typically presents as a slit or wedge defect emanating from the margin of the optic disc. The retinal nerve fiber layer is best visualized utilizing a green (red-free) filter during fundus evaluation with the slit-lamp biomicroscope. Red-free filters enhance contrast and allow for a better view of subtle nerve fiber layer defects.

Question 30

Junctions between which cells in the retina prevent proteins from entering the retina from the choroid?

Tight junctions between amacrine cells

Tight junctions between cones cells

Tight junctions between ganglion cells

Correct answer Tight junctions between the retinal pigment epithelial cells

Answer 30

The blood ocular barrier, specifically the blood retinal barrier, is the result of tight junctions at the base of retinal pigment epithelial cells and non-fenestrated capillaries. Normally, oxygen, carbon dioxide, ions, and glucose are free to enter the retina while the tight junctions prevent the passage of proteins from any leaky choroidal vessels.

Circulating drugs and hormones are capable of affecting the choroid as these vessels are more permeable than retinal vessels. The retina is mostly impervious to the effects of systemic drugs and hormones due to the blood-retinal barrier created by the RPE. Circulating drugs that affect blood pressure are capable of altering retinal blood flow.

Question 31

Which 3 of the following types of retinal cells undergo a GRADED potential (vs. an action potential)? (Select 3)

Ganglion cells

Correct answer Horizontal cells

Correct answer Bipolar cells

Correct answer Photoreceptor cells

Amacrine cells

Answer 31

GA –> Action poteintional

Certain cells of the retina, including bipolar cells, horizontal cells, and photoreceptor cells (rods and cones) do not generate action potentials like most of the rest of the neurons of the human body. Neurological signaling in these types of cells occurs via graded changes in their membrane potential. Graded action potentials allow a greater number of distinct signal amplitudes as compared to single large spikes. This is in contrast to the amacrine and ganglion cells of the retina, both of which produce action potentials.

Question 32

What is the membrane potential of a photoreceptor in the dark?

Correct answer -40 mV

-60 mV

+60 mV

+40 mV

Answer 32

-40 mV
In the darkness the membrane potential of a photoreceptor is around -40 mV. Some texts quote that the resting potential of an unstimulated photoreceptor cell is -20 mV, others state -50 mV whereas others quote -40 mV. Regardless of the value, the important thing to note is that normal cells have resting potentials of around -70 mV which is more negative than photoreceptors. This fact is attributable to the dark current which makes a photoreceptor’s resting potential slightly more positive.

Question 33

In addition to the retinal findings of bone-spicule pigmentation and retinal arteriolar attenuation, patients diagnosed with retinitis pigmentosa MOST commonly develop which of the following optic nerve changes?

Optic disc cupping

Correct answer Optic disc pallor

Optic disc edema

Optic disc hemorrhage

Answer 33

Optic disc pallor

The classic clinical triad of retinitis pigmentosa (RP) includes arteriolar attenuation, retinal bone-spicule pigmentation, and waxy optic disc pallor. Other ocular associations of retinitis pigmentosa may occur at any time during the disease, some of which may be amenable to treatment. These additional signs include the development of posterior subcapsular cataracts, myopia, and vitreous changes, such as posterior vitreous detachment and uveitis. Additionally, keratoconus, optic disc drusen, and open-angle glaucoma may also be associated with RP.

Question 34

Which layer of the retina is responsible for phagocytosis of the outer segments of the photoreceptors once they have been shed?

The inner nuclear layer

The inner plexiform layer

The outer plexiform layer

Correct answer The retinal pigment epithelium

The external limiting membrane

Answer 34

The retinal pigment epithelium plays a very important role in phagocytosis of shed outer segments. If the RPE fails to rid the retina of this debris, it will begin to accumulate which can have a significant impact on vision and may lead to macular degeneration.

The outer plexiform layer is the location at which rods and cones synapse onto horizontal and bipolar cells.

The inner nuclear layer contains the cell bodies of bipolar, horizontal and amacrine cells.

The external limiting membrane serves as a distinction between the inner segments of the photoreceptors and their respective nuclei.

The inner plexiform layer consists of synapses between bipolar, amacrine and ganglion cells.

Question 35

Which 3 of the following characteristics are considered the MOST common risk factors for the development of a retinal detachment? (Select 3)

Correct answer Aphakia

Correct answer Ocular trauma

Glaucoma

Hyperopia

Correct answer Myopia

Answer 35

The incidence of retinal detachments in patients who are aphakic and have no significant history of ocular trauma is about 1 in 10,000 persons per year. The incidence of retinal breaks in the general population is about 3.3% per year.

According to the American Optometric Association, the most common risk factors for the development of a retinal detachment are myopia (40-55%), aphakia (30-40%), and ocular trauma (10-20%).

Trauma significantly increases the risk of detachment because retinal tears or dialysis can occur, both of which can lead to the formation of a retinal detachment. Myopia greater than 8 diopters or patients with an axial length greater than 24mm have been shown to be at an increased risk for detachments as well. Studies have also shown a greater incidence of retinal detachments in patients who are aphakic; this typically occurs within the first year following surgery. It is presumed that this may be correlated to posterior vitreous detachments, which commonly occur during this period.

Question 36

Which of the following is NOT considered an increased risk factor for the development of a rhegmatogenous retinal detachment?

Correct answer Fuchs’ dystrophy

Myopia

Family history

Cataract surgery

Answer 36

Patients may possess certain characteristics that can represent an increased risk for the development of a retinal detachment, including a history cataract surgery, myopia, family history, and the presence of certain systemic diseases. Cataract surgery is known to increase the risk for developing a retinal detachment, especially if any complications occur. Patients who are myopic are also more prone to a retinal detachment, with the higher degree of myopia, the higher the risk factor. Family history is also relevant in that there may be certain genetic factors that promote inflammation and photoreceptor degeneration, which can lead to an increased risk of a retinal detachment. Additionally, systemic diseases such as Marfan syndrome, Stickler syndrome, and Ehlers-Danlos syndrome have been associated with an increased risk of retinal detachments.

Question 37

Drusen typically deposit between which layers of the retina?

The inner and outer nuclear layers

Correct answer The retinal pigment epithelium and Bruch’s membrane

The ganglion cell layer and the nerve fiber layer

The inner and outer plexiform layers

Answer 37

Drusen deposits collect between the retinal pigment epithelium (RPE) and Bruch’s membrane. The retinal pigment epithelium plays a very important role in phagocytosis of shed outer segments of photoreceptors. If the RPE fails to rid the retina of this debris, it will begin to accumulate, which can have a significant impact on vision and may lead to macular degeneration.

Question 38

You have a patient who is currently taking chloroquine for rheumatoid arthritis. You notice what appears to be early changes suggestive of retinopathy in the macular region and decide to perform an electrooculogram. If the light peak of the right eye measures 7.4 uV and the dark trough measures 4.2 uV, what is the Arden ratio, and what can you conclude from this finding?

0. 55; normal
1. 55; abnormal
2. 76; normal

Correct answer 1.76; abnormal

Answer 38

An electrooculogram uses the electrically positive cornea and electrically negative back of the eye to measure the standing potential between the two regions. The readings reflect the activity and integrity of the photoreceptors and retinal pigmented epithelium; therefore, retinal diseases that affect this area will lead to a reduction in the signal produced. The test is performed in both light and dark adapted states. Interpretation of the results involves measuring the maximal height of the potential in the light and minimal height of the potential in the dark. The Arden ratio can then be calculated by dividing the light peak value by the dark trough value. Normal values are above 1.85.

For the above case, the light peak is 7.4 and dark trough is 4.2.

7. 4/4.2 = 1.76
8. 76 is below 1.85; therefore the ratio may be considered abnormal.

Question 39

What is the MOST common complication of a posterior vitreal detachment?

Correct answer The perception of a floater

Retinal detachment

Vitreous hemorrhage

Retinal hemorrhage

Central scotoma

Answer 39

Syneresis and liquification of the vitreous are part of the normal aging process, but they also may cause a posterior vitreal detachment (PVD). Generally, PVDs occur without complication except for the perception of an annoying floater by the patient which will regress somewhat with time. Rarely, a PVD can cause a retinal tear which may lead to a retinal detachment, epiretinal membranes, and vitreal and retinal hemorrhages. Monitor the patient carefully to ensure that none of these complications develop and be sure to educate patients regarding the signs and symptoms of a retinal detachment.

Question 40

Which of the following is NOT an indication of wet age-related macular degeneration (ARMD)?

Submacular hemorrhage

Classic choroidal neovascular membrane (CNVM)

Correct answer Drusenoid pigment epithelial detachment

Occult choroidal neovascular membrane (CNVM)

Exudates

Answer 40

Drusenoid pigment epithelial detachments are a sign of dry ARMD, as there is no leakage involved. Instead, a detachment in the retinal pigment epithelium occurs due to the thickness of the soft confluent drusen. The drusen push and displace the retinal pigment epithelium.

Question 41

A 68-year old male patient presents to your office with a chief complaint of a dark spot in the center of his vision in his left eye. Upon dilated retinal examination, you observe what appears to be a macular hole; however, you do not have access to an OCT to determine if it is a full thickness or lamellar macular hole. Which of the following tests could you use in-office to aid in determining the thickness of the retinal defect?

Amsler grid

Randot stereo test

Correct answer Watzke-Allen test

Color vision test

10-2 Humphrey visual field

Answer 41

The most effective and sensitive method of evaluating a suspected macular hole is by use of optical coherence tomography (OCT); however, many general optometric practices do not have this instrument available in the their offices. Another helpful clinical test that is utilized to assess for a suspected full thickness macular hole is the Watzke-Allen slit lamp test. A narrow vertical slit-beam of light is placed over the foveal region using the slit-lamp and condensing lens. The patient is then asked to describe the line of light. The test is considered positive if the patient reports a break or significant thinning of the bar of light. Most patients with a full-thickness macular hole will report a positive Watzke-Allen test. Amsler grid testing is great for macular disease in that it is sensitive for detecting the presence of macular lesions; however, it is not specific to the type of lesion that may be present.

Question 42

Which of the following retinal findings is NOT characteristic of a diagnosis of severe non-proliferative diabetic retinopathy?

At least 1 quadrant of prominent intraretinal microvascular abnormalities

Correct answer At least 2 quadrants containing cotton wool spots

At least 2 quadrants of venous beading

At least 20 intraretinal hemorrhages in each quadrant

Answer 42

A diagnosis of severe non-proliferative diabetic retinopathy (NPDR) includes the presence of any of the following retinal observations in the absence of proliferative retinopathy:

• 20 intraretinal hemorrhages in each quadrant
• 2 quadrants of venous beading
• 1 quadrant of prominent intraretinal microvascular abnormalities (IRMA)

The presence of cotton wool spots is a characteristic feature of diabetic retinopathy but is not involved in the classification of severity of the NPDR.

Question 43

Which of the following components of the AREDS I ocular vitamin formula used for dry age-related macular degeneration is contraindicated in smokers?

Correct answer Beta-carotene

Vitamin E

Zinc

Vitamin C

Copper

Answer 43

Based upon research, there may be a link between increased risk of lung cancer and beta-carotene supplementation when used with smokers.

Question 44

Cone photoreceptors are neatly organized in which of the following arrangements in the macula?

Hectagonal mosaic

Pentagonal mosaic

Decagonal mosaic

Correct answer Hexagonal mosaic

Octagonal mosaic

Answer 44

In the macula, cone photoreceptors are densely packed in a hexagonal arrangement. As the location moves peripherally in the retina, the size and separation of the cone photoreceptors grow, and rods fill in the spaces between cones. This organization of the photoreceptor mosaic represents an optimum arrangement for efficient visual processing under a wide range of stimulus conditions.

Question 45

What are the names of the three photopigments contained within the human cones?

Chlorophyll, erythrolabe, and xanthin

Fucoxanthin, chlorophyll, and carotene

Correct answer Erythrolabe, chlorolabe, and cyanolabe

Carotene, phycoerythrin, and phycocyanin

Answer 45

he human cones contain three different photopigments allowing for the perception of a large spectrum of colors. The three photopigments are erythrolabe, chlorolabe, and cyanolabe. Erythrolabe has a peak absorbency for wavelengths measuring 565 nm and is found in long-wavelength-sensitive cones (LWS cones, L-cones or red cones). Chlorolabe maximally absorbs quanta that measure 535 nm and is found in middle-wavelength-sensitive cones (MWS cones, M-cones or green cones). Lastly, the photopigment cyanolabe displays a higher affinity for absorbing wavelengths that are 430 nm in length. These cones are known as short-wavelength-sensitive cones (SWS cones, S-c

Question 46

Flame hemorrhages that are characteristic of hypertensive retinopathy occur in what layer of the retina?

The inner nuclear layer

Correct answer The nerve fiber layer

The ganglion cell layer

The retinal pigment epithelium

Answer 46

Flame hemorrhages occur at the level of the nerve fiber layer and stem from blood loss from the inner capillary network of the retinal vasculature. These types of hemorrhages are commonly seen in hypertensive patients, vein occlusions, as well as optic neuropathies such as papilledema. The characteristic flame shape occurs because the blood will take the path of least resistance and follow the structure of the nerve fiber layer.

Question 47

The C-wave seen in an electroretinogram is created by which cells?

Mueller cells

Bipolar cells

Correct answer The retinal pigment epithelial cells

The photoreceptors

Ganglion cells

Answer 47

Electroretinograms (ERGs) are created by electric currents across the eye (the cornea is positive relative to the retinal pigment epithelium). They are a summation of the different electrical responses of retinal cells to stimuli. The A-wave of the ERG is formed by the photoreceptors. The B-wave occurs due to the responses from bipolar and Mueller cells. The C-wave is created by responses from retinal pigment epithelial cells, and the D-wave is attributable to activity of the OFF bipolar cells. The C-wave and the D-wave are not used clinically very often because they are susceptible to being obscured by blinking of the eye. It is also noteworthy that oscillations seen in the B-wave are due to responses of the amacrine cells.

Question 48

he patellar fossa of the vitreous is bounded by which other structure of the eye?

The choroid

The optic nerve head

The macula

Correct answer The posterior surface of the lens

Answer 48

The vitreous is essentially spherical in shape except for its anterior portion, which abuts the posterior surface of the lens and ciliary body, creating a saucer or knee-shaped depression into the vitreous (hence the term ‘patellar fossa’).

Question 49

A patient is concerned with an acute reduction of the acuity in the right eye. You correctly diagnose central serous retinopathy, and confirm your diagnosis with an optical coherence tomography (OCT). What is the standard treatment protocol?

Refer for intravitreal steroid injection

Treat the patient with prism as they are likely to develop diplopia

Correct answer Monitor monthly for resolution

Refer for laser treatment of the retina

Refer for cryotherapy of the retina

Answer 49

CSR is more commonly seen in middle-aged males under high-stress, who are very anxious, or with type A personalities. This condition causes fluid to leak from the choriocapillaries into the subretinal area, causing a serous detachment of the neurosensory retina. There is an associated loss of the foveal reflex, a hyperopic shift, a potential relative scotoma, and metamorphopsia. Flourescein angiography will reveal hyperfluorescence that appears like a smoke-stack. Evaluation of the posterior pole will typically display a blister-like elevation of the neurosensory retina. The patient is monitored monthly and intervention is rarely required, as most cases of CSR will resolve within roughly 6 months.

Question 50

Which of the following systemic diseases are MOST commonly associated with the presence of angioid streaks observed in the retina?

Sickle cell disease

Ehlers-Danlos syndrome

Marfan syndrome

Paget’s disease

Correct answer Pseudoxanthoma elasticum

Answer 50

Approximately 50% of patients who present with angioid streaks have an associated systemic disease; the other 50% of cases are considered idiopathic. Pseudoxanthoma elasticum (PXE) is by far the most commonly associated systemic disease in these patients. In general, PXE is a rather uncommon, inherited, generalized connective tissue disorder whereby tissues in the body containing elastin are significantly affected. Up to 85% of patients with PXE will develop ocular complications, usually after the second decade of life. The combination of PXE and ocular involvement with angioid streaks is referred to as “Gronblad-Strandberg syndrome.” Patients with PXE typically have characteristic signs of very loose skin folds and yellow skin papules that are commonly observed in the neck region, axillae, and on flexor aspects of joints. These patients also frequently suffer from cardiovascular disease caused by accelerated atherosclerosis and have an increased risk of developing gastrointestinal bleeds, which can be life-threatening.

Ehlers-Danlos syndrome is another systemic condition that is occasionally associated with the presence of angioid streaks. It is a rare, usually dominantly inherited disorder of collagen in the body that is caused by a deficiency of hydroxylysine. Systemic features include thin, hyperelastic skin, hyperextensible joints, cardiovascular disease, and other systemic lesions. Besides angioid streaks, patients with Ehlers-Danlos syndrome can also develop other ocular conditions such as lens subluxation, blue sclera, high myopia, keratoconus and retinal detachments.

Angioid streaks also occur in about 2-10% of patients diagnosed with Paget disease. Paget disease is a chronic, progressive (inherited in some cases) disease that is characterized by an enlarged skull, bone pain, frequent bone fractures, hearing loss, and cardiovascular complications. The disease may be localized to a few bones or may be generalized. In some cases, patients are even asymptomatic; however, in late stages, significant vision loss can ensue due to optic nerve compression from enlarging bone. Lab testing in these patients will show an increased serum alkaline phosphatase and urine calcium level.

Less common systemic disorders that may cause the formation of angioid streaks include sickle-cell disease, acromegaly, senile elastosis, lead poisoning, and Marfan syndrome.

Question 51

Which of the following layers of the retina represents Henle’s fiber layer in the macular region?

Inner limiting membrane

Correct answer Outer plexiform layer

Inner nuclear layer

Inner plexiform layer

Outer nuclear layer

Outer limiting membrane

Answer 51

In order to maximize cone function and acuity, the fovea displays certain structural differences when compared to the rest of the retina. At the fovea, the bipolar and ganglion cell layers are pushed aside. At the foveola, the inner plexiform layer, inner nuclear layer, ganglion cell layer, and the nerve fiber layer are all pushed aside.

Essentially, this leaves the retinal pigment epithelium, internal limiting membrane, cone photoreceptors and the outer plexiform layer. In the macula, the outer plexiform layer is known as Henle’s fiber layer. It is comprised of an oblique and radially oriented arrangement of axons of cone photoreceptors.

Question 52

The OUTER blood-retinal barrier is formed in order to prevent the leakage of fluid into the retina. At which of the following levels of the retina does this occur?

External limiting membrane

Endothelial cells of retinal vasculature

Correct answer Retinal pigment epithelium

Bruch’s membrane

Internal limiting membrane

Answer 52

The outer blood-retinal barrier is established by the tight junctions that are present between the adjacent cells of the retinal pigment epithelium (RPE). The RPE is a single layer of cells that rests upon the underlying Bruch’s membrane. It is this layer that separates the neural retina from the fenestrated vessels of the choriocapillaris. Therefore, the RPE plays an extremely important role in preventing the leakage of fluid from the choroid into the retina. Furthermore, it tightly regulates the passage of nutrients to the photoreceptors while also aiding in eliminating its waste products.

In addition to the outer blood-retinal barrier, there is also an inner blood-retinal barrier that is created by the tight junctions that reside between the endothelial cells of the retinal vasculature. The presence of both an intact inner- and outer-blood retinal barrier is essential in maintaining the precise structure and functional integrity of the retina.

Question 53

Which of the following layers of the choroid contains blood vessels with the largest diameter?

Sattler’s layer

Bruch’s layer

Correct answer Haller’s layer

Choriocapillaris

Answer 53

The choroid is a highly vascularized layer that lies between the retina and sclera. It is comprised of a network of blood vessels that supply the outer layers of the retina with essential nutrients and oxygen. The choroid can be divided into 5 layers (anterior to posterior): Bruch’s membrane, choriocapillaris, Sattler’s layer, Haller’s layer, and suprachoroid. The largest diameter blood vessels of the choroid lie within Haller’s layer; medium diameter vessels are present within Sattler’s layer. The choriocapillaris is a single layer of fenestrated capillaries that have the smallest diameter.

Question 54

Central serous retinopathy (CSR) is associated with an acute decrease in vision along with central distortion. The condition usually occurs unilaterally. Which gender and age group tends to have the highest incidence of CSR?

Correct answer Males; ages 30-50

Females; ages 20-40

Females; ages 10-20

Males; ages 50-70

Answer 54

CSR is more commonly seen in middle-aged males under high-stress, high anxiety, or with type A personalities. This condition causes fluid to leak from the choriocapillaries into the subretinal area, causing a serous detachment of the neurosensory retina. There is an associated loss of the foveal reflex, a hyperopic shift, a potential relative scotoma, and metamorphopsia. Flourescein angiography will reveal hyperfluorescence that appears like a smoke-stack. Evaluation of the posterior pole will typically display a blister-like elevation of the neurosensory retina. The patient is monitored monthly and intervention is rarely required, as most cases of CSR will resolve within roughly 6 months.

Question 55

Which 2 of the following statements are TRUE in regards to the peripheral retinal structures near the ora serrata? (Select 2)

Dentate processes are the teeth-like extensions of the pars plana that course onto the peripheral retina

Correct answer Dentate processes are the teeth-like extensions of the peripheral retina that course onto the pars plana

Oral bays are the scalloped edges of the peripheral retina that reside between the dentate processes

Correct answer Oral bays are the scalloped edges of the pars plana that reside between the dentate processes

Answer 55

The ora serrata is the ocular landmark of the junction between the peripheral retina and the pars plana of the ciliary body. The ora serrata is characterized by certain observable features, including oral bays and dentate processes. Dentate processes are the teeth-like extensions of the peripheral retina that extend onto the pars plana. They are more marked in the nasal periphery as compared to the temporal ora serrata. Oral bays are the scalloped edges of the pars plana epithelium that reside between the dentate processes of the retina.

Question 56

A retinal detachment in which vitreous contraction leads to the neurosensory retina being pulled away from the retinal pigment epithelium in the absence of a retinal break is known as which of the following?

Serous retinal detachment

Combined tractional-rhegmatogenous retinal detachment

Exudative retinal detachment

Correct answer Tractional retinal detachment

Rhegmatogenous retinal detachment

Answer 56

A tractional retinal detachment occurs secondary to the contraction of vitreoretinal membranes, which leads to the separation of the neurosensory retina from the retinal pigment epithelium (RPE). Tractional retinal detachments occur in the absence of a retinal break or tear.

Serous retinal detachments (also known as exudative or secondary retinal detachments) do not occur as a result of a retinal tear or retinal traction but as a result of subretinal fluid that accumulates between the neurosensory retina and RPE, leading to a separation of the tissue. This subretinal fluid is derived from the vessels of the neurosensory retina, the choroid, or in some cases, both.

Cases in which there is a full thickness defect in the sensory retina that causes a detachment of the retina can be classified as a rhegmatogenous retinal detachment (rhegma=break). In these cases, the retinal break permits liquefied vitreous fluid to gain access to the subretinal space, subsequently creating a separation of the tissue.

There are some instances of a retinal detachment that can occur as a result of a combination of a retinal break and retinal traction. Typically, the retinal break is caused by tractional forces from an adjacent area of fibrovascular proliferation and contraction. This is most commonly observed in advanced cases of proliferative diabetic retinopathy.

Question 57

Which of the following represents the MOST common cause of a rhegmatogenous retinal detachment in adults?

Lattice retinal degeneration

Diabetic retinopathy

Correct answer Posterior vitreous detachment

Previous cataract surgery

Choroidal melanoma

Trauma

Answer 57

Rhegmatogenous retinal detachments are caused by a full-thickness retinal break in which liquid vitreous is allowed to enter the subretinal space and separate the neuroretina from the retinal pigment epithelium (RPE). The most common cause of a rhegmatogenous detachment is a retinal tear at the site of a vitreoretinal adhesion during the advancement of a posterior vitreous detachment (PVD). Factors that may put patients at higher risk of developing this condition include the presence of lattice degeneration and previous intraocular surgery.

Tractional retinal detachments are not associated with retinal breaks but are due to tractional forces secondary to a diseased vitreous. The most common cause of tractional retinal detachments is proliferative diabetic retinopathy. Occasionally, patients with a tractional retinal detachment can develop retinal tears, leading to a combined tractional/rhegmatogenous detachment.

Exudative retinal detachments occur as a result of breakdown of the blood-retinal barriers or the RPE due to choroidal or retinal disease. Common causes of this type of detachment include choroidal tumors and posterior scleritis.

Question 58

Which of the following lifestyle choices possesses the HIGHEST risk for the development of macular degeneration?

Correct answer Smoking

Increased exposure to asbestos

Excessive alcohol consumption

Partaking in high-risk activities such as sky diving

Answer 58

Research has demonstrated that lifestyle choices such as smoking, a high body mass index, increased ultraviolet exposure and a poor diet all increase the chances of developing macular degeneration. Smoking alone increases the risk of developing macular degeneration up to 16 to 20 times. The main risk factor for the development of age-related macular degeneration (AMD) is increasing age. Other important risk factors include positive family history of AMD, Caucasian race, and the presence of age-related maculopathy (especially when associated with soft drusen).

Question 59

Which 3 of the following layers are pushed aside at the foveola? (Select 3)

Correct answer The inner nuclear layer

The internal limiting membrane

Correct answer The ganglion cell layer

Correct answer The inner plexiform layer

The photoreceptors

Retinal pigment epithelium

Answer 59

• In order to maximize cone function and acuity, the fovea displays certain structural differences when compared to the rest of the retina. At the fovea, the bipolar and ganglion cell layers are pushed aside. At the foveola, the inner plexiform layer, the inner nuclear layer, the ganglion cell and the nerve fiber layer are all pushed aside. Essentially, at the center of the foveola the cones, internal limiting membrane and the retinal pigment epithelium are the only layers that are present. Remember, the fovea is also avascular.

Question 60

During routine ophthalmoscopy, a “bright refractile plaque” is identified in a retinal arteriole. What is the most important test to order?

Correct answer Carotid Doppler ultrasound

Magnetic resonance imaging (MRI) of the brain

Electro-cardiogram (EKG)

Treadmill

Answer 60

hese plaques represent embolic phenomena referred to as Hollenhorst plaques. They are associated with atherosclerosis and a risk of stroke, possibly making all four tests appropriate. An MRI of the brain seeking other embolic activity, a treadmill to rule out coronary artery disease, and an EKG to establish a baseline are all reasonable, but the urgently needed test is a carotid ultrasound. The majority of Hollenhorst plaques comes from the carotid arteries and implies a risk of stroke in the near-term. This makes the rapid identification and institution of anti-platelet therapy with a referral to a vascular surgeon for a possible carotid an urgent referral. Hollenhorst plaque is a strong risk factor for stroke and is associated with atherosclerosis throughout the body but most particularly in the carotid artery. Therefore, a carotid Doppler ultrasound is the most important test to order.

Question 61

The proliferation of retinal pigmented epithelial cells that can be found at the junction of flat and detached retina typically indicates stability for which of the following minimum periods of time?

Correct answer 3 months

12 months

1 month

6 months

9 months

Answer 61

The presence of a pigmented demarcation line at the junction of flat and detached retina in cases of a rhegmatogenous retinal detachment (along with other features) can aid in determining the length of time the retinal detachment has been present. These demarcation lines (also known as “high water marks”) occur due to the proliferation of retinal pigment epithelial cells and commonly take about 3 months to develop. Their configuration is usually convex with respect to the ora serrata and represents sites of increased adhesion. With time, the demarcation line tends to lose its pigment and can be less obvious upon fundus examination.

Question 62

Which of the following ocular diseases represents the MOST common cause of irreversible vision loss in the United States involving individuals over the age of 50?

Correct answer Age-related macular degeneration

Hypertensive retinopathy

Diabetic retinopathy

Cataracts

Glaucoma

Answer 62

• The most common cause of vision loss in individuals over the age of 50 (in developed countries) is age-related macular degeneration (AMD). In the United States, at least 10% of patients between the ages of 65 and 75 have some impairment of visual acuity that can be attributed to AMD. Furthermore, of individuals over the age of 75, 30% have some degree of central vision loss as a result of AMD. These statistics show that the prevalence of severe visual loss increases with age.

Question 63

At which location of the retina is the peak density of rod photoreceptors located?

0. 5mm from the foveal pit
1. 0mm from the foveal pit
2. 5mm from the foveal pit

Correct answer 4.5mm from the foveal pit

6.0mm from the foveal pit

Answer 63

In the human fovea there are no rod photoreceptors present; cones are the only photoreceptors in this area, and they are perfectly arranged in a hexagonal mosaic pattern. Outside of the foveal region, the rod photoreceptors are introduced, breaking up this tight hexagonal cone packing. However, this architecture is still very organized, as cones are rather evenly spaced around the rods. Cone density rapidly falls outside of the fovea and remains at a steady density in the peripheral retina. As the cone density rapidly declines, the rod photoreceptor density quickly increases to a peak density in a ring around the fovea (also known as the “rod ring”). This is located about 4.5mm from the center of the fovea (or 18 degrees from the foveal pit).

Question 64

The presence of “sea-fan” retinopathy is associated with which of the following conditions?

Sarcoidosis

Retinopathy of prematurity

Coats disease

Correct answer Sickle cell anemia

Eales disease

Answer 64

ea fan retinopathy is characterized by abnormal, new blood vessel growth in the retina that occurs in association with sickle cell hemoglobinopathies. The anomalous red blood cell shape in sickle cell anemia, along with the increased rigidity of these red blood cells can result in obstruction of small peripheral retinal blood vessels. The occlusion of retinal arteries can cause retinal ischemia, particularly in the peripheral retina, that may lead to the development of arteriovenous anastomoses of pre-existent capillary channels. In some cases, sprouting of new blood vessels from these anastomoses can result, leading to the classic “sea-fan” configuration that is characteristic of retinopathy associated with sickle cell anemia. In more severe cases, the abnormal new blood vessel growth can continue to proliferate and cause bleeding into the vitreous, or even worse, retinal detachment due to associated fibrovascular proliferation.
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Question 65

The greatest concentration of hyaluronic acid is found in which portion of the vitreous?

The secondary vitreous

Correct answer The cortex

The primary vitreous

Cloquet’s canal

Answer 65

The vitreal cortex is formed of condensed collagen fibrils, mucopolysaccharides and proteins which serves to envelop the vitreous body. The concentration of hyaluronic acid is approximately five to ten times greater than the inner vitreous.

The primary vitreous develops at around the third week of gestation. It is formed by mesoderm. The secondary vitreous begins to develop during the ninth embryonic week. This later becomes the mature vitreous. The secondary vitreous stems from primary vitreal cells and retinal glial cells and therefore originates from neuroectoderm. The secondary vitreous expands to fill the globs while compacting the primary vitreous in the center of the globe.

The hyaloid artery is a branch of the ophthalmic artery and is important for delivering nutrients to the lens and structures behind the lens during development. The artery disintegrates before birth leaving a canal in the primary vitreous called Cloquet’s canal. Remnants of this artery are often perceived as “floaters”

Question 66

Which 3 of the following ophthalmologic manifestations are associated with malignant hypertension? (Select 3)

Correct answer Cotton wool spots

Hollenhorst plaques

Chorioretinal retinal atrophy

Correct answer Flame-shaped hemorrhages

Correct answer Papilledema

Acute angle closure

Answer 66

Though unlikely to present in the office, a sudden significant rise in blood pressure can damage the delicate retinal vessel walls. This leads to flame-shaped hemorrhages or infarction of the nerve layer, producing cotton wool spots, and, in the most severe and long-lasting cases, papilledema. On the other hand, Hollenhorst plaques reflect an embolic phenomenon from thrombotic disease, usually from the carotid artery. Acute angle closure and chorioretinal atrophy are not associated with malignant hypertension.

Question 67

Which retinal layer serves as an interface between the retina and the vitreous?

The retinal pigment epithelium

The external limiting membrane

Correct answer The internal limiting membrane

The nerve fiber layer

Answer 67

The layers progress in the following way:
Retinal pigment epithelium-> photoreceptor cell layer-> external limiting membrane-> outer nuclear layer-> outer plexiform (synaptic) layer-> inner nuclear layer-> inner plexiform (synaptic) layer-> ganglion cell layer-> nerve fiber layer-> internal limiting membrane

The internal limiting membrane forms the innermost boundary and is composed of footplates of Muller cells. This layer serves as the interface between the vitreous humor and the retinal tissue. It is attached at the ora, optic nerve, and macula. The external limiting membrane consists of intercellular junctions of photoreceptor cells. The nerve fiber layer contains the ganglion cell axons. The retinal pigment epithelium is a single layer of pigmented cells that functions in three ways: to form part of the blood-retinal barrier, to phagocytosize fragments from shedding of photoreceptor discs, and to metabolize and store the vitamin A used in forming photopigment.

Question 68

n patients diagnosed with retinitis pigmentosa, which of the following inheritance patterns leads to the MOST severe presentation of the disease with the WORST prognosis?

Autosomal-dominant

Isolated, without family history

Correct answer X-linked

Mitochondrial

Autosomal-recessive

Answer 68

Retinitis pigmentosa (RP) is a retinal dystrophy in which the rod photoreceptor cells are initially preferentially affected, with eventual subsequent degeneration of the cone photoreceptors as well. Retinitis pigmentosa may develop as a result of an isolated sporadic disorder without any other family history or secondary to a genetic mutation (usually of the rhodopsin gene). RP has also been shown to be associated with certain systemic conditions.

The autosomal-dominant form of retinitis pigmentosa, along with the isolated sporadic form are the most common types and usually have the best prognosis. Autosomal-recessive types are less common and typically have an intermediate or guarded prognosis. The least common and most severe form of RP is due to an x-linked genetic mutation and commonly results in complete blindness by the time patients are in their 20’s or 30’s.
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Question 69

Question [ You were correct ]
Which of the following ocular conditions is NOT considered a “white dot syndrome?”

Acute posterior multifocal placoid pigment epitheliopathy (APMPPE)

Birdshot retinochoroidopathy

Serpiginous choroidopathy

Correct answer Polypoidal choroidal vasculopathy

Answer 69

White dot syndromes (also known as primary idiopathic inflammatory choriocapillaropathies) are ocular inflammatory conditions that are characterized by the presence of white dots on the fundus. The most common visual symptoms of patients presenting with these diseases include blurred vision and visual field loss. The exact etiology of these ocular conditions is unknown; however, some investigators believe there to be a connection with bacterial and viral infections, genetic predispositions, and/or autoimmune associations. Classically recognized white dot syndromes include: acute posterior multifocal placoid pigment epitheliopathy (APMPPE), birdshot retinochoroidopathy, multiple evanescent white dot syndrome (MEWDS), serpiginous choroiditis, punctate inner choroidopathy (PIC), and multifocal choroiditis with panuveitis (MCP).

Polypoidal choroidal vasculopathy is an idiopathic choroidal vascular disease that is characterized by a dilated network of choroidal blood vessels that have multiple terminal aneurysmal protuberances (in a polypoidal appearing fashion). This condition is not considered a “white dot syndrome.”

Question 70

Question [ You were incorrect ]
Which of these lists of retinal structures is correctly ordered from most central (smallest diameter) to furthest from central (largest diameter)?

Foveola, fovea, perifoveal area, parafoveal area

Fovea, foveola, perifoveal area, parafoveal area

Fovea, foveola, parafoveal area, perifoveal area

Correct answer Foveola, fovea, parafoveal area, perifoveal area
Explanation - The foveola is about 0.35 mm in diameter and contains the densest population of cones with the smallest cross-sectional diameter of all photoreceptors. The fovea centralis is a shallow depression in the center of the macular region. It is about 1.5 mm diameter. The annular zone around the fovea contains an inner parafoveal area that contains retinal bipolar cells and ganglion cells and has about a 2 mm diameter. Outside of there is the perifoveal area that contains ganglion cells and has a diameter of about 3.5 mm.

Answer 70

Foveola, fovea, parafoveal area, perifoveal area

Question 71

Which of the following retinal structures represents the WEAKEST attachment site for the posterior cortical vitreous?

Vitreous base

Correct answer Retinal blood vessels

Optic nerve head

Macula

Answer 71

he vitreous body is normally attached posteriorly to several structures of the eye including the peripheral retinal blood vessels, macula, optic nerve head, and the vitreous base (which straddles the ora serrata). As the vitreous degenerates with age, a posterior vitreous detachment is a common observation that occurs as a result of the separation of the posterior hyaloid membrane from the internal limiting membrane of the retina; this can occur at any point posterior to the vitreous base. The most common location of a posterior vitreous detachment is at the site of vitreopapillary separation.

The strongest area of attachment of the vitreous is at the ora serrata (vitreous base), followed by the optic nerve head. The adhesion in the area of the fovea is fairly weak, while the weakest attachment site of the vitreous body is along the peripheral retinal blood vessels.

Question 72

A 35 year-old male presents to your office with sudden loss of vision in his left eye that began a few days ago following a chest-compressing injury that occurred at his work. Dilated fundus evaluation reveals multiple, superficial, white retinal patches, along with several superficial peripapillary hemorrhages. What is the MOST likely diagnosis for this patient?

Terson syndrome

Commotio retinae

Correct answer Purtscher’s retinopathy

Valsalva retinopathy

Retinal detachment

Answer 72

Purtscher’s retinopathy is a retinal condition that typically occurs following severe trauma (especially to the head) or in patients with a history of a recent chest compressive injury. Patients will commonly present with severely decreased visual acuity in one or both eyes that develops either immediately or within 48 hours following the event. Retinal observations commonly include superficial, white, retinal patches resembling cotton-wool spots, pre-retinal and/or retinal hemorrhages, macular edema, dilated retinal veins, and possible optic disc edema or optic disc pallor.

The underlying pathophysiology of the development of Purtscher’s retinopathy is not fully understood; however, the classic mechanism proposes that the injury creates an intravascular hydrostatic shock wave that travels to the retinal vasculature and results in endothelial cell damage of the retinal veins, macular capillaries, and radial peripapillary capillaries. The problem with this theory is that it does not account for the development of this type of retinopathy in patients without a traumatic event (emboli, pancreatitis, connective tissue diseases, bone marrow transplantation, etc.). There is no known treatment for Purtscher’s retinopathy except for proper management of the underlying cause. Prognosis for visual recovery is variable because, although retinal findings tend to resolve within a few weeks, about 50% of patients will experience persistent prolonged blurring of central vision due to irreversible macular or optic nerve damage.

Terson syndrome occurs when a vitreous hemorrhage is accompanied by a subarachnoid hemorrhage. Commotio retinae appears as a grey-white discoloration of the retina that occurs following blunt ocular trauma. It is a result of the disruption of the photoreceptor outer-segments. This condition can present peripherally and may cause severe or permanent visual loss if damage occurs in the region of the macula.

Question 73

At which location in the eye is the most common site of occurrence for a branch retinal vein occlusion (BRVO)?

Correct answer Superior temporal

Superior nasal

Inferior nasal

Inferior temporal

Answer 73

Branch retinal vein occlusions (BRVO) are the most common type of vascular occlusion encountered in clinic. Common associations include, but are not limited to: hypertension, diabetes, and congestive heart failure. The superior temporal vein is the most frequently involved, followed by the inferior temporal vein. The nasal quadrants are rarely involved. The pathogenesis of a BRVO results from compression of the vein by the overlying artery impeding blood flow return. The blood accumulates and eventually leaks out of the vessel, resulting in retinal hemorrhages. Some researchers have suggested that the superior temporal quadrant of the eye has the greatest amount of arterial/vein crossing junctions, and therefore possesses a higher likelihood of involvement. Visual acuity may be compromised, depending upon the presence of macular involvement. Greater amounts of ischemia increase the chances of complications such as neovascularization of the retina and rubeosis iridis.

Question 74

You are performing binocular indirect ophthalmoscopy on a patient and drop and crack your 20D condensing lens. You are able to find an old 30D condensing lens to complete the examination. How will the magnification and field of view change with the 30D lens as compared to the 20D lens?

Both the magnification and field of view will increase

The magnification will increase, and the field of view will decrease

Both the magnification and field of view will decrease

Correct answer The magnification will decrease, and the field of view will increase

Answer 74

As the power of the condensing lens increases, the field of view increases but the magnification decreases. Additionally, the working distance will decrease as well.

It may be easier to think about this concept in terms of fundus lenses because we commonly switch back and forth between powers depending on pupil size, while most practitioners only use one condensing lens (20D). The field of view is larger with a 90D lens, and the magnification is less with a 90D lens as compared to a 78D lens; this can be applied to condensing lenses used with binocular indirect ophthalmoscopy as well.

Question 75

Although controversial, it has been purported that supplementation of vitamin A is important in the management of retinitis pigmentosa. Which of the following agents, when taken in excess amounts, may interfere with the uptake of Vitamin A?

Vitamin K

Vitamin B12

Correct answer Vitamin E

Calcium

Answer 75

Vitamin A plays an important role in vision, and it is currently believed that daily supplementation of 15,000IU of Vitamin A may aid in decreasing the progression of retinitis pigmentosa. Research has demonstrated that taking increased levels of vitamin E simultaneously with higher doses of vitamin A may interfere with the uptake and distribution of vitamin A. Therefore, it is recommended that patients taking vitamin A for the management of retinitis pigmentosa avoid ingestion of higher amounts of vitamin E.

Question 76

Which of the following correctly lists the layers of the retina beginning with the retinal pigment epithelium and moving anteriorly?

Retinal pigment epithelium, external limiting membrane, outer nuclear layer, photoreceptor layer, outer plexiform layer, inner nuclear layer, inner plexiform layer, nerve fiber layer, ganglion cell layer, internal limiting membrane

Correct answer Retinal pigment epithelium, photoreceptor layer, external limiting membrane, outer nuclear layer, outer plexiform layer, inner nuclear layer, inner plexiform layer, ganglion cell layer, nerve fiber layer, internal limiting membrane

Retinal pigment epithelium, photoreceptor layer, outer nuclear layer, external limiting membrane, outer plexiform layer, inner plexiform layer, inner nuclear layer, ganglion cell layer, nerve fiber layer, internal limiting membrane

Retinal pigment epithelium, outer nuclear layer, external limiting membrane, photoreceptor layer, outer plexiform layer, inner plexiform layer, inner nuclear layer, nerve fiber layer, ganglion cell layer, internal limiting membrane

Answer 76

In order:

1) The retinal pigment epithelium is a single layer of pigmented cells that functions to form part of the blood-retinal barrier, phagocytose fragments from shedding of photoreceptor discs, and metabolize and store vitamin A which is used in forming photopigment
2) The photoreceptor cell layer contains the outer and inner segments of rods and cones
3) The external limiting membrane consists of intercellular junctions of photoreceptor cells
4) The outer nuclear layer contains the cell bodies and nuclei of the rods and cones
5) The outer plexiform (synaptic) layer is made up of the fibers of rods and cones and synapses between photoreceptor cells and cells from the inner nuclear layer
6) The inner nuclear layer contains cell bodies of several types of neurons and Muller cells.
7) The inner plexiform (synaptic) layer contains the synapses of bipolar cell axons and gangion cell dendrites
8) The ganglion cell layer contains amacrine cells, Muller cell bodies, and astroglial cells
9) The nerve fiber layer contains the ganglion cell axons
10) The internal limiting membrane forms the innermost boundary and is composed of footplates of Muller cells

Question 77

What is the pre-synaptic connection for a rod cell?

Amacrine cells

Bipolar cells

Correct answer None

Ganglion cells

Horizontal cells

Answer 77

Rod cells do not have pre-synaptic connections. Rhodopsin is embedded in the discs of the outer segment of the rod and absorbs a photon of light, causing an electrical change in the membrane of the rod. It is necessary for several rods to summate in order to signal the presence of a stimulus. Rods then release glutamate postsynaptically to bipolar and horizontal cells.

Question 78

Which chamber lies adjacent to the retina?

Retinal chamber

Anterior chamber

Posterior chamber

Correct answer Vitreous chamber

Answer 78

The vitreous chamber is the largest of the three spaces within the eye and lies next to the retina. The anterior chamber, as its name implies, is the most anterior space and is bound by the cornea and iris. The posterior chamber is bounded by the iris, lens, and retina. There is no retinal chamber.

Question 79

The internal limiting membrane of the retina is formed by a combination of glial cell processes and which other cell type?

Correct answer Muller cells

Amacrine cells

Bipolar cells

Horizontal cells

Answer 79

The internal limiting membrane is formed by radial feet processes of Muller cells along with other glial cell constituents. Muller cell processes extend throughout the length of the retina except for the retinal pigment epithelium. Their cell bodies are found in the inner nuclear layer. Muller cells, along with segments of the photoreceptors, create tight junctions and serve to form the external limiting membrane.

Question 80

What is the name of the additional retinal layer that many nocturnal vertebrate animals posses that functions to enhance visual sensitivity at low light levels?

Plica semilunaris

Dua’s layer

Retina lutea

Tunica vascularis

Correct answer Tapetum lucidum

Answer 80

The tapetum lucidum, commonly found in nocturnal vertebrate animals (not present in humans or swine), is an additional retinal layer that has a highly reflective, iridescent appearance. The function of this layer is to reflect light back onto the retina in the exact same path that it was originally oriented. As light passes the rod and cone photoreceptors, it reflects off of the tapetum lucidum, which then allows the light to pass through the photoreceptors yet again. This effectively amplifies the light several fold, significantly enhancing visual sensitivity during low light conditions. This layer is what causes an animal’s eyes to shine or glow in the dark.

Question 81

Which 3 of the following statements BEST represent the phenomena responsible for the dark appearance of the fovea during fluorescein angiography imaging? (Select 3)

The retinal pigment epithelial cells in the foveal region are smaller and more densely packed

Correct answer The absence of retinal blood vessels in the center of the fovea

The absence of choroidal blood vessels in the center of the fovea

An increased density of carotenes in the foveal region

Correct answer An increased density of xanthophyll in the foveal region

Correct answer The retinal pigment epithelial cells in the foveal region are larger and contain more melanin

Answer 81

In a normal fluorescein angiography image, the dark appearance of the fovea occurs as a result of three phenomena.

• The center of the fovea does not contain retinal blood vessels (foveal avascular zone)
• The choroid below the fovea does contain a network of blood vessels that fills with fluorescein in the early phase; however, there is blockage of this background choroidal fluorescence due to the increased density of xanthophyll in the foveal region
• Additionally, background choroidal fluorescence is blocked due to the retinal pigment epithelial (RPE) cells in the fovea, which contain more melanin and are larger than RPE cells elsewhere in the retina

Question 82

Which type of laser technology depends on the birefringence properties of the retinal nerve fiber layer to measure its thickness?

Optical coherence tomography

Correct answer Scanning laser polarimetry

Scanning laser ophthalmoscopy

Confocal scanning laser tomography

Answer 82

Birefringence is the splitting of a light ray (or wave) into two components as it passes through an anisotropic material. In an anisotropic material, the index of refraction is dependent on the direction of light within the material. There are several components of the ocular structure that can be considered birefringent, including the cornea, lens, and retinal nerve fiber layer (RNFL). The basis of measuring RNFL thickness in a scanning laser polarimeter (such as the GDx VCC) is due to the birefringent properties of the RNFL. The RNFL is composed of highly ordered parallel axon bundles that contain microtubules and other cylindrical intracellular organelles that have a diameter smaller than the wavelength of light. This highly ordered structure is the source of birefringence of the RNFL. When light waves from the instrument are incident on the birefringent RNFL, the waves are split into two different components that travel at different velocities, creating a phase shift. This phase shift is also known as retardation and is directly proportional to the thickness of the RNFL. Because the cornea and lens are also considered birefringent structures, this instrument must compensate for the anterior segment birefringence in order to produce an accurate measure of the RNFL thickness.