INRODUCTION
Age-related macular degeneration (AMD) is the leading cause of severe central visual acuity loss in 1 or both eyes in people over 50 years of age in the United States
EPIDEMIOLOGY
Prevalence
Nonexudative (dry): 80 – 85%
Exudative (wet): 10 – 15%
NORMAL CHANGES DURING AGING IN THE RETINA
Photoreceptor: ↓ in density and distribution
Pigment epithelium:
Loss of melanin granules
Formation of lipofuscin granules
Accumulation of residual bodies
Accumulation of basal laminar deposits
Choriocapillaris: progressive involutional changes
RISK FACTORS:
Non modifiable
↑ age
Positive family history
Hyperopia
Light iris colour
Female gender
Modifiable
Hypertension
Hypercholesterolemia
Smoking
Cardiovascular disease
GENETICS
Allelic variants of genes encoding for alternate complement pathway particularly complement factor H (CFH)
Mutations : in Chr 1q31 , Account for 75% of genetic risk 10q26 (Tyr402His) → 5 fold chance
10q (Ala69Ser) → 7 fold chance
NON NEOVASCULAR AMD
Clinical features:
Drusen:
· Small, round, yellow lesions located at the level of the RPE within the macula
· Ultrastructurally, the material includes
¨ Basal laminar deposits (granular lipid-rich material and widely spaced collagen fibers)
¨ Basal linear deposits (phospholipid vesicles and electron-dense granules within the inner aspect of Bruch’s membrane)
· The thickened inner aspect of the Bruch’s and RPE may detach from the rest of the Bruch’s → PED (early hyperfluorescence on FFA)
· Do not usually cause any symptoms since the overlying photoreceptors are unaffected (visual disturbance and ↓ dark adaptation are rare)
Management
Patient education
· Patient should be taught how to recognise symptoms of advanced disease
Amsler’s grid
· White lines on a black background should be used
· Should be performed by the patient on a daily basis
Preferential hyperacuity meter
· Designed to detect recent onset of neovascular membrane and hence can distinguish it from dry AMD
· Earlier diagnosis → earlier treatment → better visual outcome
· Subjects are asked to evaluate a series of linear dots and note if true or perceived distortions are present
· In a patient with RPE elevation, a geometric shift in photoreceptor location occurs → a different set of photoreceptor fields is stimulated → perception that certain dots in the line are in a different position relative to their true location in space
Micronutrients
· AREDS
¨ Antioxidants and vitamins (500 mg vitamin C, 400 IU vitamin E, and 15 mg beta carotene) and zinc (80 mg zinc oxide and 2 mg cupric oxide to prevent zinc-induced anemia)
¨ According to National cancer institute, beta carotene ↑ the risk of lung cancer in chronic smokers and should therefore be avoided people who smoke or have cancer
¨ Not beneficial for normal patients, early AMD
¨ Beneficial for B/L intermediate AMD or U/L severe AMD.
Anti - Vegf injections form the main stay of treatment for wet form of ARMD .
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