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Clinical Medicine - Dx's > Vision > Flashcards

Vision Flashcards

1
Q

4 interfaces of Light

A

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

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2
Q

What shape is the lens in the relaxed eye?

A

Flat (ciliary muscles are relaxed) - distance vision

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3
Q

Miosis

A

Small pupil

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4
Q

Mydriasis

A

Large pupil

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5
Q

PERRLA

A

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

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6
Q

Hyperopia

A

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

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7
Q

Myopia

A

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

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8
Q

Bitemporal Hemianopsia

A

Both LATERAL fields are gone

Tumor of optic chiasm

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9
Q

Homonymous Hemianopsia

A

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

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10
Q

Central Scotoma

A

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.

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11
Q

Strabismus

A

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
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12
Q

Amblyopia

A 
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.

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13
Q

Nystagmus

A 
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

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14
Q

Ptosis

A

Eyelid Droop

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

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15
Q

Entropion vs Ectropion

A

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

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

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16
Q

Cataract

A

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
17
Q

Glaucoma (general)

A

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
18
Q

Open Angle Glaucoma

A

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
19
Q

Closed Angle Glaucoma

A

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
20
Q

Retinoblastoma

A

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.

21
Q

Anterior Ischemic Optic Neuropathy (AION)

A

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

22
Q

Papilledema

A

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

23
Q

Optic Neuritis

A

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
24
Q

Retinal Detachment (general)

A

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

25
Q

Rhegmatogenous Retinal Detachment

A

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

26
Q

Non-Rhegmatogenous

A

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

27
Q

Arteriosclerosis of Retina

A

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

28
Q

Malignant Hypertension

A

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.

29
Q

Retinal Artery Occulsion

A

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).

30
Q

Retinal Vein Occlusion

A

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

31
Q

Age Related Macular Degeneration (General)

A

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

32
Q

Macular Degeneration (DRY - non-neovascular)

A

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

33
Q

Macular Degeneration (Wet)

A

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

34
Q

Diabetic Eye

A

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.

35
Q

Background Retinopathy

A

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)

36
Q

Proliferative Retinopathy

A

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.

37
Q

Retinopathy of Prematurity

A

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

38
Q

TORCH Syndomes

A

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

Clinical Medicine - Dx's (4 decks)

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