PREGUNTAS Flashcards
How do anatomists define the macula?
That portion of the posterior retina with xanthophyllic pigment and two or more layers of ganglion cells.
How large is the macula?
5-6 mm (5000-6000 microns)
What is the name for the small, slightly concave portion of the posterior retina that is devoid of capillaries and occupied almost exclusively by cones?
Foveal avascular zone.
How large is the fovea?
1.5 mm, 1500 microns, 1 disk diameter (DD), 5 degrees.
What area is defined by the lack of a ganglion cell and inner nuclear layer?
Foveola: approx. 350 microns, approx. equal to the foveal avascular zone (FAZ).
What is the deepest portion of the retina supplied by branches of the central retinal artery
The inner portion of the inner nuclear layer.
What is the name for the depression in the center of the foveola?
Umbo, clivus, light reflex.
What is the exception to the role of retinal blood supply of the choriocapillaris?
Choriocapillaris normally supplies the outer portions of the retina up to the outer part of
the inner nuclear layer—a cilioretinal artery can sometimes supply an area of inner retina
What makes up the outer portion of the blood-retina border?
Tight junctions between adjacent RPE cells (zonulae occludentes).
What makes up the inner portion of the blood-retina border?
Retinal capillary endothelial cells.
What is the chromatophore for all four classes of human visual pigments (rhodopsin, red, blue, and green), and how is it oriented to the plane of the lipid bilayer?
11-cis-retinaldehyde is oriented parallel to the plane of the lipid bilayer and, therefore, perpendicular to the path of photons.
When are old rod disks and cones shed?
Rod disks are shed at dawn and cone disks are shed at dusk.
Why is the neuroretina usually devoid of water?
The RPE has a high capacity for water transport.
What syndrome can be associated with congenital hypertrophy of the RPE?
Gardner Syndrome (intestinal polyposis).
What are the parts of the ciliary body?
The ciliary body has two parts, which are pars plicata ciliaris and pars plana ciliaris. The pars plicata is a circumficial zone about two and a half millimeters in the anterior posterior dimension, extending posteriorly from the iris root and contains 70 to 80 ciliary processes. The pars plana ciliaris is about three millimeters wide nasally and four and a half millimeters temporally, and extends from the pars plicata anteriorly to the ora serrata posteriorly. The posterior part of the pars plana is covered with vitreous base.
What artery is the origin for both the choroid and the central retinal artery?
Ophthalmic artery.
How is pars plana vitrectomy performed?
There are three incisions made in pars plana, for which one is used for infusion of fluid to maintain intraocular pressure. The second port is used for illumination with fiber optics. The third opening is used to allow a vitrectomy instrument to be used in the vitreous cavity. Other instruments (such as laser probes, intraocular scissors, etc.) are interchangeable through one of these openings.
When is open sky vitrectomy performed?
Open-sky vitrectomy is an operation used for desperate cases of detached retina. One of the best indications for this procedure is grade V ROP.
What is the best predictor of metastatic potential for retinoblastoma histopathologically?
Optic nerve invasion.
What wavelengths of light pass through the vitreous gel?
The vitreous body is a clear gel that allows the transmission of about 90% of light
wavelengths between 300 to 1400 nm.
What is the most common cause of cotton wool spots?
Diabetic retinopathy.
What forms the external limiting membrane of the retina?
It is formed by tight junctions between the photoreceptor inner segments and the lateral margins of Müller’s cells.
What is a highly characteristic histologic finding in the iris pigment epithelium of diabetics?
Lacy vacuolization of the iris pigment epithelium.
What organ is the most common site of metastasis for uveal melanomas?
Liver.
What type of collagen is vitreous composed of?
Type II collagen, which is specific for vitreous.
What is the most abundant component of the vitreous body?
Water is the major component of the vitreous body. It comprises 98% of its volume.
What is the optical function of the vitreous?
It acts as an ultraviolet filter. There is decreased transmission at 350 to 300 nm wavelength and zero thereafter as well as decreased infrared transmission at 800 nm wavelength and zero after 1600 nm
How often do patients with acute posterior vitreous detachment and vitreous hemorrhage have retinal breaks?
70% will have peripheral retinal breaks.
How far is the ora serrata from the limbus?
6 mm
Where do we make the incision for pars plana vitrectomy?
An incision that is made three to four millimeters posterior to the limbus goes to the anterior part of the pars plana and avoids the vitreous base and the pars plicata. The blood vessels for pars plana are radially oriented and the circumficial incision rarely causes any bleeding into the eye.
Is the insertion of the superior rectus muscle anterior or posterior to the ora serrata?
Posterior
How far is the equator from the limbus?
16 mm.
How often is there no family history of retinitis pigmentosa in a patient with the disease?
40% of patients with retinitis pigmentosa will have no family history of the disease.
What is the probability that the next child of a patient with a history of bilateral retinoblastoma will develop the disease?
50%.
In what other tumor besides retinoblastoma may Flexner-Wintersteiner and
Homer Wright rosettes be seen?
Medulloepithelioma.
What are Elschnig spots?
They are choroidal infarcts seen in severe hypertensive retinopathy.
What is Terson’s syndrome?
Retinal and vitreous hemorrhage associated with posttraumatic subarachnoid and subdural hemorrhage.
What is the most common cause of spontaneous vitreous hemorrhage in adults?
Diabetic retinopathy.
A 60-year-old patient has an acute, spontaneous vitreous hemorrhage that prevents visualization of the fundus. What diagnostic test should next be requested for in this case?
Ultrasonography to rule out the possibility of retinal detachment or a neoplasm.
What is Cloquet’s canal?
It is the embryological remnant of the hyaloid vascular system.
What can be observed in essentially normal eyes that are remnants of the fetal vasculature?
Mittendorf’s dot, vascular loops, Bergmeister’s papilla.
At what time during embryonic development does the primary vitreous first form
During the 3rd through 9th weeks.
What is the source of the secondary vitreous?
Vitreous fibrils are formed by the inner retina while the Müller cells produce hyaluronic
acid
By which month is Cloquet’s canal formed?
5th month.
The tertiary vitreous forms what ocular structures?
Zonular fibers.
What is the most common presentation of PHPV?
Leukocoria.
What are the most common characteristics of PHPV?
Unilateral in 90% of cases, normal full term infants, microphthalmia, shallow AC, natural course leads to blindness.
What are the most common fundus abnormalities that are seen in hereditary vitreoretinopathies?
Equatorial and perivascular (radial) lattice, retinoschisis, chorioretinal atrophy, optic atrophy.
What are the 2 hereditary vitreoretinopathies most commonly not associated with systemic abnormalities?
Wagner’s Disease and Jansen’s Disease.
What differentiates Wagner’s and Jansen’s Disease?
Jansen’s Disease has a high incidence of retinal detachment. Wagner’s Disease is not
associated with retinal detachment.
What disease is associated with heredity vitreoretinopathies and systemic abnormalities?
Stickler’s Syndrome.
What systemic abnormalities are generally found in Stickler’s Syndrome?
- Hyperextensibility and enlargement of joints.
- Arthritis and spondyloepiphyseal dysplasia.
- Orofacial findings include mid-facial flattening, cleft palette, and the Pierre-Robin
malformation complex (micrognathia, cleft palette, and glossoptosis).
Why is it important to recognize Stickler’s Syndrome?
Because of the high incidence of retinal detachment which are normally very difficult to repair.
What is the most common inheritance pattern in Stickler’s Syndrome?
AD
What are the findings in ocular ischemic syndrome?
Stenosis of the carotid artery can lead to ocular ischemia, ipsilateral absence of arcus
senilis, iris neovascularization and midperipheral retinal hemorrhages.
What composes asteroid hyalosis?
Calcium soaps.
What is the ratio of pericytes to retinal vascular endothelial cells in normal retinal blood vessels?
1 to 1 ratio.
What type of configuration can choroidal melanomas assume on B-scan ultrasound?
Collar button configuration.
What are the criteria for diabetic clinically significant macular edema (CSME)?
Retinal thickening within 500 microns of the center of the fovea.
Hard exudates at or within 500 microns of the center of the fovea if associated with thickening of adjacent retina.
Retinal thickening 1 DD in size or larger if within 1 DD from the center of the fovea.
What are the retinal findings of preproliferative diabetic retinopathy?
Cotton wool spots, dark blot hemorrhages, vascular changes (beading, looping, sausage-
like), and intraretinal microvascular anomalies (IRMA).
What did the Diabetes Control and Complications Trial demonstrate?
Aggressive efforts to normalize blood sugars with insulin pumps may initially worsen the retinopathy in some patients during the first few months of treatment. Ultimately, strict control of blood sugar with intensive insulin therapy:
Reduced the risk of development of retinopathy in patients without retinopathy by 76%
Reduced by 47% the risk of development of severe nonproliferative and proliferative retinopathy in patients with mild to moderate nonproliferative retinopathy, and slowed the progression of retinopathy in patients with mild to moderate nonproliferative retinopathy by 54%.
What group of patients can show a worsening of diabetic retinopathy with intensive control?
Patients with mild or moderate NPDR at the time of change to intensive control.
What treatment did the DRS recommend for high-risk PDR?
PRP - 1200 or more 500 micron burns separated by 1/2 burn width.
What were the conclusions of the Early Treatment Diabetic Retinopathy Study
(ETDRS)?
Focal laser coagulation should be considered for all eyes with CSME because treatment reduces the risk of visual loss by 50%.
Panretinal photocoagulation (PRP) should be considered in patients who are at high risk of developing proliferative diabetic retinopathy (PDR) while mild to moderate nonproliferative diabetic retinopathy (NPDR) can be observed.
Systemic aspirin (650 mg/day) does not prevent the development of PDR, nor does it increase the risk of visual loss or vitreous hemorrhage.
Describe Severe NPDR as defined by the ETDRS.
Severe NPDR was defined by the ETDRS as any one of the following: intraretinal heme and microaneurysms in 4 quadrants; venous beading in 2 quadrants; IRMA in 1 quadrant. Remember the 4:2:1 rule for severe NPDR.
How did the ETDRS define very severe NPDR?
2 of 4,2,1
What groups of patients are predisposed to poor visual acuity even after photocoagulation?
Those with diffuse macular edema, macular ischemia, hard exudates in the fovea, or marked CME.
What is the risk of developing high-risk PDR within one year for patients with very severe NPDR?
Very severe NPDR - 45% risk of developing high-risk PDR within one year.
What systemic conditions may lead to a worsening of diabetic retinopathy?
Hypertension, severe carotid vascular disease, and pregnancy.
Is photocoagulation recommended if high-risk PDR develops during pregnancy?
YES
Which should be treated first, CSME or high-risk PDR?
CSME
Describe the technique for focal laser photocoagulation.
Focal - a 50-100 micron spot size, 0.1 second or less duration, attempt to whiten or darken all leaking microaneurysms between 500 and 3000 microns from the center of the macula.
Which should be done first - focal laser or cataract extraction?
Focal laser.
What type of lasers may be more successful for PRP in patients with vitreous heme?
Krypton red or diode lasers.
What are potential adverse effects of panretinal photocoagulation of diabetic retinopathy?
- Angle closure glaucoma from choroidal effusion.
- Decreased night vision.
- Central scotoma from worsening diabetic macular edema.
- Retinal detachment from regression and contracture of neovascular fronds.
What are the different types of central retinal vein occlusions?
Nonischemic CRVO. Ischemic CRVO. Papillophlebitis.
What is the probability that the next child of a patient with unilateral retinoblastoma but without a family history of the disease will develop retinoblastoma?
6%
What is the most common primary intraocular malignancy?
Uveal malignant melanomas.
Where is the most frequent primary site of choroidal metastatic tumors?
Women: breast.
Men: lung.
Other causes include kidney, GI tract, prostate (rarely).
What are the layers of Bruch’s membrane?
- The inner basal lamina of the RPE.
- The inner collagenous zone.
- Band of elastic fibers.
- Outer collagenous zone.
- Basal lamina of the choriocapillaris.
What are Roth spots and what can cause them?
They are white spots in the middle of an intraretinal hemorrhage, which are thought to represent a fibrin thrombus occluding a ruptured blood vessel. They can be caused by:
1. infectious endocarditis
2. leukemia
3. anemia
4. hyperviscosity syndromes, eg. Multiple myeloma, Waldenstrom macroglobulinemia.
What are some of the causes of a bull’s eye maculopathy?
- Drugs (chloroquine, chlorpromazine, thioridazine, tamoxifen).
- Cone dystrophy.
- Stargardt’ s disease.
- Inverse (central) retinitis pigmentosa.
- Batten’ s disease.
What are the risk factors for the development of choroidal neovascularization in DMAE
- Cigarette smoking.
- Elevated serum cholesterol.
- Large, bilateral, soft drusen.
- Pigment irregularities in the macula.
What factors decrease the risk of choroidal neovascularization in age-related macular degeneration?
- Exogenous estrogen use in postmenopausal women.
- Increased serum carotenoid levels.
How can retinoblastoma present clinically?
Leukocoria
Strabismus.
Secondary glaucoma.
Pseudouveitis (hypopyon, hyphema, red eye, pain) in older children. Proptosis.
Orbital inflammation.
What are the most common organs involved with hematogenous spread of retinoblastoma?
Bones, lymph nodes and liver.
What is the fundus appearance of retinoblastoma?
Endophytic tumors project into vitreous, while exophytic tumors present as retinal
detachment.
What is the treatment for retinoblastoma?
- Enucleation.
- Radiotherapy if good vision is present.
- Photocoagulation for tumors <3mm diameter or <2 mm thickness.
- Cryotherapy for tumors <3.5 mm or <2 mm thickness.
- Systemic chemotherapy for orbital recurrences and metastatic disease (skull, orbit,
long bones, viscera, spinal cord, lymph nodes).
Note: photocoagulation and cryotherapy are contraindicated if vitreous seeding is present.
What are retinal capillary hemangiomas called?
Von Hippel’s disease.
How many patients with Von Hippel’s disease are associated with systemic lesions (Von Hippel-Lindau’s syndrome)?
Twenty five percent have systemic lesions such as:
1. Hemangioblastomas of the cerebellum, brainstem and spinal cord.
2. Cysts of the kidneys, pancreas, lungs, ovaries, and epididymis.
3. Phaeochromocytoma and hypernephroma.
How would you workup patients with Von Hippel’s disease and their relatives?
- Physical examination.
- Urinalysis.
- 24-Hour urine collection for levels of vanillylmandelic acid (VMA).
- Renal ultrasonography.
- Abdominal CT scan.
- Brain CT or MRI scan.
What is the treatment of Von Hippel Lindau’s disease?
- Photocoagulation or cryotherapy if it is affecting or threatening vision.
- Genetic counseling.
- Refer for medical treatment of the systemic lesions of Von Hippel-Lindau’s
syndrome.
What is Wyburn-Mason syndrome?
- It is a phacomatoses consisting of
- Large, dilated, tortuous vessels forming AV communications in the retina,
- Racemose hemangiomas in the midbrain causing seizures and hemiparesis, and
- Hemangiomas in the ipsilateral pterygoid fossa, mandible and maxilla.
What are the causes of peripheral retinal neovascularization?
- Diabetes mellitus.
- V ein occlusion.
- Sickle cell anemia.
- Retinal vasculitis (sarcoidosis, collagen vascular disease, radiation retinopathy, pars
planitis). - Retinopathy of prematurity.
- Familial exudative vitreoretinopathy.
- Eales disease.
What are the critical signs of sickle cell retinopathy?
Peripheral neovascularization (sea fans), sclerosed peripheral vessels, and a dull gray
peripheral fundus resulting from ischemia.
How would you manage sickle cell retinopathy?
- Photocoagulation to areas of capillary nonperfusion.
- Pars plana vitrectomy for tractional retinal detachment or vitreous hemorrhage.
What is the cause of retinal and optic disc colobomas?
Incomplete closure of the fetal fissure.
What other ocular features may be associated with retinal colobomas?
Posterior embryotoxon. Non-rhegmatogenous retinal detachment. Strabismus.
Nystagmus.
Posterior lenticonus.
What is the mode of inheritance of choroideremia?
X-linked recessive.
What are the ERG findings in choroideremia?
It may be normal in the early stages, but the scotopic ERG will eventually become non-
recordable and the photopic ERG severely diminished by the end of the first decade.
What metabolic error is present in gyrate atrophy?
Inborn error of the mitochondrial enzyme ornithine aminotransferase, leading to increased levels of ornithine in CSF, aqueous, serum and urine.
How is gyrate atrophy treated?
Pyridoxine and arginine-restricted diet.
What is the mode of inheritance of Stargardt’s disease?
AR
What systemic diseases may be associated with congenital hypertrophy of the retinal pigment epithelium?
Gardner’s syndrome and familial adenomatous polyposis (FAP). At least 4 lesions in each eye are generally considered necessary to suggest the possibility of either FAP or Gardner’s syndrome.
What systemic diseases may be associated with angioid streaks?
- Paget’ s disease.
- Pseudoxanthoma elasticum.
- Ehlers-Danlos syndrome.
- Hemoglobinopathies (homozygous sickle cell disease, thalassemias).
- Acromegaly.
- Calcinosis.
- Senile elastosis.
What posterior segment features may be caused by Ehlers-Danlos syndrome?
High myopia and retinal detachment from giant tears.
When does the retina become vascularized in an infant?
The nasal retina is usually vascularized by 36 weeks gestation, while the temporal retina
is usually completely vascularized by term.
Which infants are at risk for developing retinopathy of prematurity (ROP)?
Infants born less than 36 weeks of age, weighing less than 2000 g and who have received
supplemental oxygen.
When should neonates at risk for ROP be screened?
Initially, they should be screened between postconceptual ages of 32 and 36 weeks after birth then every 2 weeks until 36 weeks if the fundi are normal and weekly if there is evidence of zone 1 or 2 disease present.
How often does ROP in infant eyes spontaneous regress?
85%.
What is a retinal detachment?
It is a separation of the sensory retina from the RPE by subretinal fluid.
What is the significance of pigment cells (tobacco dust) in the retrolental space of a patient complaining of sudden onset of floaters and flashing lights?
It suggests the possibility of a retinal tear. The cells represent macrophages containing RPE cells.
What potential complication can occur in areas of “white-without-pressure”?
Giant tears can occur along the posterior border of “white-without-pressure.”
