Vision

Question 1

4 interfaces of Light

Answer 1

Air:Cornea
Cornea:Aqueous Humour
Aqueous Humour: Crystalline Lens
Crystalline Lens: Vitreous Humour

Question 2

What shape is the lens in the relaxed eye?

Answer 2

Flat (ciliary muscles are relaxed) - distance vision

Question 3

Miosis

Answer 3

Small pupil

Question 4

Mydriasis

Answer 4

Large pupil

Question 5

PERRLA

Answer 5

Pupils Equal size and Round, Reactive to Light and Accommodation.

Question 6

Hyperopia

Answer 6

Farsighted - means cannot see near objects and eyeball is too SHORT or lens too flat so focal point is behind retina; lower refractive power.
Tx
Convex Lens or + diopter

Question 7

Myopia

Answer 7

Nearsighted - means cant see far objects, eyeball is too LONG or lens to CURVED so image is in front of retina
Tx
Concave Lens of - diopter

Question 8

Bitemporal Hemianopsia

Answer 8

Both LATERAL fields are gone

Tumor of optic chiasm

Question 9

Homonymous Hemianopsia

Answer 9

Full loss of L or R vision; nasal on one side and temporal on the other.
Damage to one of the optic tracts.

Question 10

Central Scotoma

Answer 10

Blind spot where most acute vision s/b (fovea is affected)
Related to age related Macular Degeneration

Peripheral Scotoma’s also occur - affecting peripheral vision.

Question 11

Strabismus

Answer 11

Strabismus is misalignment of the eyes, which causes deviation from the parallelism of normal gaze. Diagnosis is clinical, including observation of the corneal light reflex and use of a cover test. Treatment may include correction of visual impairment with patching and corrective lenses, alignment by corrective lenses, and surgical repair.

Complications:

• double vision
• brain may suppress signal from bad eye leading to blindness

Causes:

• extraoccular mm weakness
• different refractive powers btwn eyes
• obstruction of vision in one eye (cataract)
• neurological defect - causing mm problems

Classifications: "...tropias"
Eso - inward
Exo - outward
Hyper - upward
Hypo - downward

Question 12

Amblyopia

Answer 12

Amblyopia is functional reduction in visual acuity of an eye caused by disuse during visual development. Severe loss of vision can occur in the affected eye if amblyopia is not detected and treated before age 8
Also Caused by:
Strabismus
Cataract 
Capillary Hemangioma

Sx
Poor spatial acuity, depth perception, contrast distinction.

Question 13

Nystagmus

Answer 13

Rapid involuntary eye movement when trying to fixate on an object. 
Can occur in any plane or be rotary
Causes: 
Cerebellar disturbance
CN VIII inner ear issues
Drug use
Brainstem issues

PATHOLOGICAL within 30 degrees of centre

Congenital:
-most common non-pathological form
Horizontal plane
Decreased acuity

Acquired:
Vestibular - assx vertigo (BPPV)
Rotary

Question 14

Ptosis

Answer 14

Eyelid Droop

Common in: Horner’s Syndrome, Myasthenia Gravis, Damage o CNIII, Congenital, MM weakness

Question 15

Entropion vs Ectropion

Answer 15

Entropion (IN) - lower eyelid turns in = red eye

Ectropian (EXTERNAL) - lower eyelid turns out = red eye and lacrimation.

Question 16

Cataract

Answer 16

A cataract is a congenital or degenerative opacity of the lens. The main symptom is gradual, painless vision blurring.

Sx
scattered light rays = cant focus on fovea
can cause blindness
pupil looks opaque
tinting of lens - blue
poor night vision
NO PAIN

Risk Factors:
Diabetes
Wilson's Dx - copper storage in lens
Atopic Dermatitis
Corticosteroids
Trauma
Age

Question 17

Glaucoma (general)

Answer 17

Glaucomas are a group of eye disorders characterized by progressive optic nerve damage in which an important part is a relative increase in intraocular pressure (IOP).

Pathology: 
Elevated intraoccular pressure
Increased cup/disc ratio
Thinning of Sclera
Optic nerve + Retinal artery compression
Necrosis of Retinal cells
Damage to lens d/t nutritional deficiencies
May lead to Cataracts

Question 18

Open Angle Glaucoma

Answer 18

Increased IOP d/t decreased outflow of aqueous humour through trabecular meshwork.
Two Types:
Primary - genetic mutation
Secondary - clogging of meshwork with debris (pigment or fibrous matter)

SX
NO PAIN
SLOW progression
Loss of peripheral vision (tunnel vision)
May cause BLINDNESS

Question 19

Closed Angle Glaucoma

Answer 19

MEDICAL EMERGENCY
Two Types:

Primary - shallow anterior chamber (common in hyperopia bc eye is shorter).
In people with narrow angles, the distance between the pupillary iris and the lens is also very narrow. When the iris dilates, forces pull it centripetally and posteriorly causing iris–lens contact, which prevents aqueous from passing between the lens and iris into the anterior chamber (this mechanism is termed pupillary block).

Secondary - another pathology causes it. The mechanical obstruction of the angle is due to a coexisting condition, such as proliferative diabetic retinopathy (PDR), ischemic central vein occlusion, uveitis, or epithelial down-growth

SX
Blurred vision
Halos
Red eye
PAIN
Photophobia
Tunnel vision
BLINDNESS with 24HOURS

Question 20

Retinoblastoma

Answer 20

Retinoblastoma is a cancer arising from the immature retina.

Sx
Leukocoria (a white reflex in the pupil)
Strabismus
Pain
Mydriasis
Likely Bilateral 
40% congenital

Sequelae: spread of cancer to brain via optic nerve.

Question 21

Anterior Ischemic Optic Neuropathy (AION)

Answer 21

Ischemic optic neuropathy is infarction of the optic disk. The only constant symptom is painless vision loss. Diagnosis is clinical. Treatment is ineffective.

Sx
Painless vision loss
Diagnostically - see pale, swollen opti disc

Sequelae: papilledema

Question 22

Papilledema

Answer 22

Papilledema is swelling of the optic disk due to increased intracranial pressure; swollen hyperemic nerve head also. Optic disk swelling from causes that do not involve increased intracranial pressure (eg, malignant hypertension, thrombosis of the central retinal vein) is not considered papilledema.

Sx
NO vision loss if acute
If chronic - exudate may be seen on retina.
Pt’s may have nausea or vomitting d/t pressure

Question 23

Optic Neuritis

Answer 23

Optic neuritis is inflammation of the optic nerve. Symptoms are usually unilateral, with eye pain and partial or complete vision loss.

Most cases result from demyelinization of optic nerve d/t MS

Sx
Blurred vision
Central vision loss
Eye pain
Problems with dim light or colours
May involve extraoccular mm

Question 24

Retinal Detachment (general)

Answer 24

MEDICAL EMERGENCY
Retinal detachment is separation of the neurosensory retina from the underlying retinal pigment epithelium. The most common cause is a retinal tear (rhegmatogenous detachment).

SX
peripheral or central vision, often described as a curtain or dark cloud coming across the field of vision. 
Flashers
Floaters
Curving of straight lines
PAINLESS

Causes: trauma, contracture of vitreous humour, inflammation
Effects: ischemia; necrosis; blindness

Question 25

Rhegmatogenous Retinal Detachment

Answer 25

Rhegmatogenous detachment is the most common for and is caused by a retinal tear which allows vitreous humour between the layers. Retinal detachment is painless. Early symptoms of rhegmatogenous detachment may include dark or irregular vitreous floaters (particularly a sudden increase, flashes of light (photopsias), and blurred vision. As detachment progresses, the patient often notices a curtain, veil, or grayness in the field of vision. If the macula is involved, central vision becomes poor. Patients may have simultaneous vitreous hemorrhage

Question 26

Non-Rhegmatogenous

Answer 26

Traction retinal detachment: A tractional retinal detachment occurs when fibrous or fibrovascular tissue, caused by an injury, inflammation or neovascularization, pulls the sensory retina from the retinal pigment epithelium. Serous detachment results from transudation of fluid into the subretinal space. Causes include severe uveitis, especially in Vogt-Koyanagi-Harada disease, choroidal hemangiomas, and primary or metastatic choroidal cancers

Question 27

Arteriosclerosis of Retina

Answer 27

On Opthalmascopy - see sliver/copper wire vessels; nicking of vessels; exudate; possible hemorrhages d/t micro tears; vessels are narrower.

Question 28

Malignant Hypertension

Answer 28

Affects vessels in choroid and retina Exudate at RPE will cause retinal detachment Occlusion of retinal arteries = retinal infarct, swelling and necrosis Presents as cotton wool spots on opthalmoscopy - cotton wool spots are infarcted nerve fibres.

Question 29

Retinal Artery Occulsion

Answer 29

Central artery or branch --> distal ischemia causing diffuse or segmental infarction. Acute swelling and opacity occur. CHERRY RED SPOT pale retina with a cherry red macula (ie, the cherry red spot) result from obstruction of blood flow to the retina from the retinal artery, causing pallor, and continued supply of blood to the choroid from the ciliary artery, resulting in a bright red coloration at the thinnest part of the retina (ie, macula).

Question 30

Retinal Vein Occlusion

Answer 30

Retinal vein occlusion is a blockage of the small veins that carry blood away from the retina. Retinal vein occlusion is most often caused by hardening of the arteries (atherosclerosis) and the formation of a blood clot. Often = upregulation of angiogenic factors --> neovasculization of retina, optic nerve head and iris bc we NEED to drain the eye. May cause: Vision loss Glaucoma

Question 31

Age Related Macular Degeneration (General)

Answer 31

Most common cause of vision loss in the elderly Risk: smoking, genetics, age. Disturbance of RPE, Bruch + Choriocapillaris

Question 32

Macular Degeneration (DRY - non-neovascular)

Answer 32

Dry (atrophic): The dry form occurs in 90% of people with AMD. All AMD starts as the dry form. The retinal pigment epithelium plays a critical role in keeping the cones and rods healthy and functioning well. Accumulation of waste products from the rods and cones can result in drusen, which appear as yellow spots. Areas of chorioretinal atrophy (referred to as geographic atrophy) occur in more advanced cases of dry AMD. Membrane thickens, longer diffusion barrier causes ischemia. There is no elevated macular scar (disciform scar), edema, hemorrhage, or exudation. SX Dry AMD: The loss of central vision occurs over years and is painless, and most patients retain enough vision to read and drive. Central blind spots (scotomas) usually occur late in the disease and can sometimes become severe. Symptoms are usually bilateral. Funduscopic changes include the following: Changes in the retinal pigment epithelium Drusen Areas of chorioretinal atrophy

Question 33

Macular Degeneration (Wet)

Answer 33

Wet AMD occurs when new abnormal blood vessels develop under the retina in a process called choroidal neovascularization (abnormal new vessel formation). Localized macular edema or hemorrhage may elevate an area of the macula or cause a localized retinal pigment epithelial detachment. Eventually, neovascularization causes a disciform scar under the macula. SX Wet AMD: Rapid vision loss, usually over days to weeks, is more typical of wet AMD. The first symptom is usually visual distortion, such as a central blind spot (scotoma) or curving of straight lines (metamorphopsia). Peripheral vision and color vision are generally unaffected; however, the patient may become legally blind (< 20/200 vision) in the affected eye or eyes, particularly if AMD is not treated. Wet AMD usually affects one eye at a time; thus, symptoms of wet AMD are often unilateral. Funduscopic changes include the following: Localized retinal elevation Retinal edema Gray-green discoloration under the macula Exudates in or around the macula Detachment of retinal pigment epithelium (visible as an area of retinal elevation) Subretinal hemorrhage in or around the macula

Question 34

Diabetic Eye

Answer 34

Eye is a major site of pathology in diabetes bc endothelial cells, nerve cells and the lens of the eye do not require insulin to take up sugar therefore in diabetes if uncontrolled these tissues will have abnormally high sugar content.

Question 35

Background Retinopathy

Answer 35

Develops first and causes increased capillary permeability, microaneurysms, hemorrhages, exudates, macular ischemia, and macular edema (thickening of the retina caused by fluid leakage from capillaries), micro occlusion -- non-perfusion of retina = upregulation of vascular epithelium growth factor --> angiogenesis. Vision symptoms are caused by macular edema or macular ischemia. However, patients may not have vision loss even with advanced retinopathy. The first signs of nonproliferative retinopathy are Capillary microaneurysms Dot and blot retinal hemorrhages Hard exudates Cotton-wool spots (soft exudates)

Question 36

Proliferative Retinopathy

Answer 36

May lead to vitreous hemorrhage and traction retinal detachment. Proliferative retinopathy is characterized by abnormal new vessel formation (neovascularization), which occurs on the inner (vitreous) surface of the retina and may extend into the vitreous cavity and cause vitreous hemorrhage. May cause wrinkling of retina = straight lines appear curved. KEY - neovascularization of the optic disk.

Question 37

Retinopathy of Prematurity

Answer 37

Birth - nasal retina is vascularized, temporal retina is incompletely vascularized (normal)

Question 38

TORCH Syndomes

Answer 38

Toxoplasmosis, Other, Rubella, Cytomegalovirus, Herpes --- cause many in-utero patholgies including occular changes.