Age Related Macular Degeneration (ARMD) is degeneration of the most sensitive part of the retina (sensory part of the eye) called macula. It is mostly seen in people over the age of 50 years.
Initially it is a silent disease and can affect one eye to begin with. At this stage it might be detected by an ophthalmologist on routine retina evaluation. Gradually vision loss increases mainly in the center allowing vision at sides, but makes reading or close work difficult without the use of special low vision aids.
The early stages of ARMD typically start with appearance of deposits beneath the retina called Drusen. These do not affect vision very much by themselves and most people with Drusen will never have a serious loss of vision. However, certain changes may occur that lead to the late stage of ARMD which leads to marked visual loss.
The exact cause of macular degeneration is not known though following risk factors have been identified: age, heredity, sex (women more affected then men), light ocular pigmentation, hypertension, cardiovascular diseases, diabetes, photo toxicity and cigarette smoking.
There are 2 types of ARMD: "Dry" and "Wet"
Dry ARMD is the most common form accounting 80-90% of all cases and is associated with ageing. It is caused by degeneration in visual cells leading to yellow-white deposits in layers of retina called drusen or formation of atrophic areas in macula. Overtime dry ARMD may develop into wet type.
Wet or Exudative ARMD is the more severe variety where abnormal blood vessels form beneath the macula which leak fluid and blood under the retina. Blood under the retina is toxic to the photoreceptors and can lead to severe loss of function of retina.
If only one eye is affected to begin with, the symptoms may not be noticeable in early stages. Gradually as disease progresses or if both eyes are involved, reading or close work may become difficult. Common symptoms are distortion of objects which are looked at directly, for e.g. bulges or curved appearance of a straight door, distorted print lines in book (metamorphopsiae), missing of letters or words while reading, a dark or blank spot in the center of vision, (scotoma) or fading of colors specially blue (dyschromatopsiae)
As initially it is a silent disease, mostly it is picked up in a routine retina examination by an ophthalmologist .The retinal examination done by an ophthalmoscope will show the findings of this disease process. To assess the condition in detail, certain other test are done:
There is no prevention of ARMD. Early detection is the key to prevent severe loss of vision. All individuals above 50,especially if there is a family history of ARMD, history of cardiovascular disease, light ocular pigmentation, should get annual retinal check up for the same. Anyone experiencing following symptoms should consult an ophthalmologist immediately:
Smoking is a risk factor and should be avoided at all costs if any of the risk factor is present.
According to some recent international multicentric trials, multivitamins may slow down progression of dry ARMD. However, excess of fat soluble multivitamins can have their own side-effects and thus consult your doctor before regularly taking multivitamin pills.
Dry ARMD There is no permanent cure for dry ARMD. The aim of management is to keep a vigilant check on progression of disease and take measures to improve functional capability of the patient.
Wet ARMD The mainstay of treatment of wet ARMD at present is injection of Anti-VEGF drugs into the eye. These are special molecules designed to stop further development of blood vessels. So once the abnormal vessel growth under the retina gets inhibited the leakage of fluid and blood also reduces. However at present these injections need to be repeated at regular intervals as once the effect of the drug wanes off the abnormal vessels star growing again. The two main such drugs being used at present are AVASTIN & LUCENTIS. Presently we donot have a drug which can altogether end the process of this abnormal neovascularisation. A lot of research is ongoing to find a permanent cure for ARMD.
Other treatment modalities available for wet ARMD are