Lec 26 Visual System and Gaze Disorders Flashcards
What are the 3 layers of the eye?
external: sclera and cornea
intermediate: iris, ciliary body, choroid
internal: retina
What is the iris?
circular pigmented membrane enclosing pupil
What is the ciliary body?
just beneath sclera + lateral to lens
makes aqueous humor
contains ciliary muscle that allows lens to change shape to focus
What is the choroid?
layer of connective tissue and blood vessels between sclera and retina
suplles nutrients to the eye
What are the three fluid compartments of the eye?
- anterior and posterior chambers in front of lens [separated by iris]
- vitreous body [between back of lens and retina, contains jelly-like substance
What do the anterior/posterior chambers of eye contain?
aqueoue humor
What is an example of aqueous humor disorder?
glaucoma [excess aqueous humor in eye from drainage obstruction and other causes]
What is the lens?
biconvex structure, refracts light to focus it on retina
What is blood supply to lens?
avascular
What suspends the lens? what happens to these over time?
- zonules
- they weaken with advanced age which is what causes eye problems as you get older
What are two examples of lens disorders?
presbyopia
cataracts
what is presbyopia?
loss of ability of lens to change shape [focus between distance and near]
– occurs with age, lens hardens and less elastic
what are cataracts?
clouding/yellowing of lens with advanced age
- initially have mild disturbance of vision then progressive loss
What is glaucoma?
excess aqueous humor (over production, under drain)
causes increased pressure thus lead to optic nerve injury and decreased vision
What are clinical signs of glaucoma?
- high IOP
- cupping of optic nerve
- peripheral visual field loss progressing inward
What are two types of glaucoma?
- primary open angle
- closed angle
What is primary open angle glaucoma?
- wide/open angle betwen iris and cornea
- due to slow clogging of drainage canals of eye
- asymptomatic early but can advance to irreversible vision loss
- most common type in elderly
What is closed angle glaucoma?
- less common
- higher risk in asians, females, hyperopia
- angle/drainage canal between iris + cornea closed or narrow
- creates suddent rise in IOP –> need meds or laser surgery
- signs: ocular pain, redness, N/V, headche, blurred vision, halos around light
What is age-related macular degeneration [ARMD]? risk factors?
ARMD = degenerative disease of macula/fovea –> get decreased central vision/blind spot
risk factors: age > 70, fair skin, family history, smoking, heart disease
What are the two types of ARMD?
- wet and dry
What is dry ARMD? signs?
- gradual visual loss due to formation of small yellow deposits under macula
- early = asymptomatic, straight lines appear crooked, advanced = central blind spot
What are drusen?
small yellow deposits under macula, cause dry ARMD
What is wet ARMD?
- sudden, severe visual loss due to growth of blood vessels + bleeding under retina
decrease risk: eat fruits/veggies
What is diabetic retinopathy?
- increased blood glucose damages retinal capillaries –> breakdown blood retinal barrier
- causes retinal ischemia
what are findings of diabetic retinopathy?
- early = asymptomatic
- may have microaneurysms, hard exudates, intraretinal hemmorrhage
- cotton wool spots
- retinal ischemia