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  • Ashish Ahuja

Age related Macular degeneration

Updated: Apr 18, 2021







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 .




Monthly injections are needed - intial 3 injections , once a month followed by regular follow up and to repeat injection when advised by your doctor .







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