Sunday 6 March 2011

Understand Age Related Macular Degeneration So You Can Know The Suitable Treatment


Age related macular degeneration is simply increased degeneration or death of macular photoreceptors with age, usually above 50 years, leading to severe diminution of vision. Normally photoreceptors decrease with age as any other permanent tissue that does not divide. About 90% of AMD are of the wet type and the other 10% are of the dry type. But what's the difference between both?
Before knowing each type I want to assure that you know the following piece of information. The light receptors (photoreceptors which receive light to make us see) lay on a layer of cells called Retinal Pigment epithelium layer RPE (contain black pigments to minimize light reflection and give a more clear image). These two layers have a minimal normal space in between.
Wet Type:
In the wet type, the choroidal vessels (choroid is the vascular layer under the retina) abnormally extend or grow under the macula (area that makes us see detailed coloured vision) in the potential space normally found between the photoreceptors and the retinal pigment epithelium. This leads to sub macular edema and hemorrhage and eventually separation of the two layers leading to macular photoreceptors' degeneration and scarring. This causes a marked decrease in vision.
Treatment of Wet type:
Doctors thought of ligating these abnormal vessels using laser and stopping the edema and hemorrhage. But the macula is the most sensitive and contains the highest concentration of receptors in the whole body, so their therapeutic attempt will harm nearby healthy receptors in such sensitive area.
They modified this technique by using a dye for staining blood vessels and thus they can see their target in a more clear way and act on it using laser, however macular damage remained an avoidable loss (although it is much less in this case). Recently they are using anti vascular epithelium growth factors (such as Mucagen, Avastin) which are injected intravitreal to inhibit the growth of the abnormal blood vessels under the macula.
Dry Type:
The real cause is unknown, but what's clear is that the Retinal pigment epithelium layer RPE degenerates first followed by photoreceptors' degeneration. This type is less progressive than the wet type and starts peripherally (usually).

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