Flashcards in Visual loss pathology Deck (12)
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1
Major causes of vision loss
-Age-related macular degeneration
-Glaucoma
-Cataracts
-Diabetic retinopathy
2
Age-related macular degeneration (AMD)
-Senescence and dysfunction of the retinal pigment epithelium (RPE), accompanied by sub retinal drusen deposits, and occasional choroidal neovascularization
-Vision loss due to dysfunction of photoreceptors (receive nutrients from choroid along w/ RPE)
-2 types: dry and wet (exudative) AMD
-Symptoms: blurry vision, mostly in central vision (central scotoma)
3
Dry AMD
-90% of AMD cases
-Drusen deposits accumulate btwn RPE and bruch's membrane near macula
-Atrophy of RPE results in visual loss (photoreceptor dysfunction), areas of atrophy result in coalescing "geographic atrophy" around macula
-Rx: antioxidants, regular exams, stem cell Rx in the works
4
Wet AMD
-10% of AMD cases
-New abnormal vessels grow from choroidal circulation into subretinal space
-These form choroidal neovascular membranes (CNVM)
-Subretinal fluid accumulates and subretinal hemorrhage and scaring occurs
-All lead to loss of photoreceptors and vision
-Rx: anti-VEGF, lasers
5
Glaucoma
-Increase in intraocular pressure (IOP) that eventually leads to damage to ganglion cell axons at the optic nerve head and resultant vision loss
-Results from an obstruction of flow for the aqueous humor (usually around the canal of schlemm)
-2 types: primary open angle (POAG) and acute closed angle (ACAG)
6
Primary open angle glaucoma (POAG)
-Slow progression (chronic), asymptomatic until late stage
-Due to blockage of schlemm or trabecular meshwork leading to inability to drain aqueous humor
-Increase IOP, damages ganglion cells and vascular supply
-Generally bilateral
-Symptoms: visual field loss and blurry vision, halos around lights
-Rx: decrease aqueous humor production w/ beta (b1) blockers, carbonic anhydrase inhibitors, a1 agonists
-Can also increase outflow by using cholinergics and prostaglandin analogs
7
Acute closed angle glaucoma (ACAG)
-Acute and abrupt blockage of aqueous outflow
-Shallow anterior chamber predisposes to this, since iris is in close proximity to cornea
-Pupillary dilation can precipitate an attach because it increases tightness of contact btwn iris and lens
-Fluid must flow btwn lens and iris, around iris, then btwn iris and cornea. A blockage anywhere in this path results in ACAG
-Symptoms: nausea, vomiting, pain
-Rx: cholinergics to constrict pupil, osmotic agents (glycerol, mannitol) to decrease IOP, laser iridectomy to increase outflow
8
Cataracts 1
-Due to lens opacities that impede vision
-Cortical degeneration: opacities that radiate around the periphery of the lens, caused by swelling and liquefaction of younger cortical fiber cells
-Nuclear sclerosis: opacity of central area of lens often w/ lens discoloration, caused by deterioration of older lens fibers
9
Cataracts 2
-May result from systemic diseases (diabetes) and are correlated w/ UVB exposure
-Present w/ blurry vision and glare, double vision (monocular diplopia), near-sightedness (myopia), and second sight (need for reading glasses disappears due to myopia)
-Management: extraction of lens and replacement when severe and affecting daily lives
10
Diabetic retinopathy (DR)
-Diabetes affects retinal vasculature (specifically the venous side of retinal capillary beds), and is a venous occlusive disease
-The resulting damage to retina leads to visual loss
-2 types: proliferative and non-proliferatvie
-Both are chronic diseases
-Sx: blurry vision, dark floaters, visual field loss, poor night vision
11
Non-proliferative DR
-Venous dilation accompanied by micro aneurysms in venous capillaries (+ exudate)
-Microaneurysms result in dot-blot appearance of retina as veins are deep in the retina (AV nicking)
-Cotton wool spots: patches of lost retina
-Macular edema (loss of central vision, lost vision can be in patches)
-Rx: controlling diabetes/HTN, lasers
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