Age-related Macular Degeneration with the longevity of the population increase and with increased exposure to oxidants in the food, and environment; exposure to UV rays, blue light in LEDs (lights, mobile screens, TV screens) etc, the prevalence of macular degeneration is increasing.
What is AMD/ARMD?
There is a normal process of degeneration within the pigment epithelial cells of the Retina. In the case of AMD, this process is hastened leading to the accumulation of lipofuscin debris (drusens in the Bruch’s membrane and basal lamina). Excessive accumulation of debris causes the atrophy of RPE cells, in turn leading to dysfunction and death of photoreceptors. When this process is exactly at the site of the fovea, there is visual diminution. Early stages, wherein there is only an accumulation of yellow, refractile bodies (drusens), are known as NON-NEOVASCULAR/ Dry dry age-related macular degeneration.
In advanced cases, with deterioration of Bruch’s membrane and RPE layer, the barrier activity is lost and new vessels are formed from the choroidal circulation, either under the RPE (type 1) or under the Neuro Ophthalmology (type 2). This is called CNVM (choroidal neovascular membrane) and the disease, is NEOVASCULAR/WET AMD. These new vessels are leaky and cause pigment epithelial (PED) or Neurosensory (NSD) detachment causing falls in vision. The vessels may also bleed and cause subretinal/submacular hemorrhage which can be very damaging to the existing photoreceptors.
What are the symptoms of AMD?
Early stages may have no symptoms. In advancing cases,
- The blurring of vision which may be indolent or sudden
- Metamorphopsia (things appearing smaller or bigger than usual, borders of objects appear bent/crooked/wavy)
- Scotomas (black spots in the visual field)
- Inability to see in dim light
Management of AMD (Age-related macular degeneration)
Investigations:
- Simple slit lamp biomicroscopy with a 90D lens can detect both non-neovascular and neovascular AMD.
- Fundus Color photograph as a comparative tool.
- OCT can help in quantifying the amount of leak and detachment of the retina. Also helps in characterizing the type of PED (serous/hemorrhagic/fibrovascular/drusenoid)
- FFA/ICGA- angiography to delineate the choroidal neovascular membrane (location/type/extent)
- AMSLER Chart Screening
Treatment:
- Dry Age-related Macular Degeneration – Only the presence of drusens usually requires no treatment. Educate patients about a diet rich in antioxidants and the use of blue light blocker glasses/screen protectors. Inform patients about potential worsening symptoms and how to monitor using an Amsler chart. If soft drusens or large druse are present, or if the other eye’s condition deteriorates, doctors may prescribe AREDS 2 formula oral medications: Vitamin E-400IU, Vitamin C-500mg, Copper 2mg, Zinc 80mg, Lutein 10mg, zeaxanthin 2mg.
- Wet Age-related Macular Degeneration – in the case of a neovascular membrane, the treatment is with Intravitreal AntiVEGF +/- Intravitreal triamcinolone so as to shrink and stabilize the vessels and decrease the ooze.
Doctors typically perform surgical intervention for significant submacular haemorrhages, as the iron from red blood cells has the potential to harm photoreceptors. It involves removing the vitreous and injecting gas along with AntiVEGF and tissue plasminogen activator, so as to displace the blood from the fovea and resolve the bleeding faster.
