शुक्रवार, 28 जून 2013

What is ARMD?

Age Related Macular Degeneration (ARMD)  is a disease that causes progressive degeneration of the macula.Macula is the central part of the retina that allows us to see fine details.Many people develop Macular Degeneration as part of body's ageing process.This  condition ,which is the commonest cause of blindness in the Western World after the age of 65 ,is now becoming common in our country too .In the past ,treatment for ARMD was limited ,but extensive research on the subject has made its management possible ,thereby helping the elderly retain their vision and improve their quality of life .

With improvements    in socio-economic conditions ,comes longevity and with longevity incidences of Age Related Macular Degeneration  increase.

Forms of Macular Degeneration 

The two most common types of Age Related Macular Degeneration are :

(1)Dry Macular Degeneration (Atrophic):  This form is the more common form of the disease and accounts for 90% of all ARMD.It is caused by ageing and thinning of the tissues of the macula .Vision loss is usually gradual and may take years .Low vision aids may help the patient in reading and near vision work .

(2)Wet Mcular Degeneration (Exudative ):This form is characterised by development of abnormal blood vessels beneath the retinal pigment epithelial layer .These vessels can bleed and eventually cause scarring ,leading to profound loss of central vision in weeks to months .Hence ,Wet ARMD needs to be treated as early as possible .

This form is characterised by choroidal Neovasculariztion (CNV),the development of abnormal blood vessels beneath the Retinal Pigment Epithelium(RPE) layer of the retina .These vessels can bleed and eventually cause macular scarring which can result in profound loss of central vision (disciform scar).

What are the Symptoms of Macular Degeneration ?

Early stages of Macular Degeneration may not cause decrease in vision .Sometimes only one eye loses vision while the other eye continues to see well for many years.The condition may be hardly noticeable in its early stages .But when both eyes are affected reading and close work can become difficult .You may experience one or more of the following symptoms .

(1)Straight lines look distorted ,especially at the centre of vision .

(2)Colors look dim .

(3) Words on a page look blurred.

(4)A dark or empty area appears in the centre of vision .

Progression of Macular Degeneration 

If there is macular degeneration in one eye ,then the fellow is at high risk of developing macular degeneration as well .The risk of the fellow eye developing macular degeneration is reported to be 38%-55%.

Treatment for ARMD 

Although accounting for 10% of all cases of ARMD ,Wet ARMD causes severe vision loss .Recent studies have proven that selected patients have much less chance of significant visual loss if they are treated by Laser photocoagulation (Hot Lasers )than if they are not treated .only 20% of the patients of Wet ARMD can be treated with Laser photocoagulation.

PDT is a type of cold laser which is used in patients on whom the neo vascular membrane is below the centre point of the eye (fovea i.e sub  foveal ).The aim of this treatment is to stablise the existing vision , but vision improvement occurs in less than 5% of the patients following the treatment.

Photodynamic Therapy (PDT) is a cold laser treatment that is still being used to treat patients with wet AMD, though much less frequently now that useful drugs are available.  It may be tried in combination with Lucentis or other anti-angiogenic drugs, as that may increase the effectiveness.   In PDT, a drug (Visudyne) that reacts to light is injected into the patient's arm. Once it moves up to the eye it pools in those damaged new blood vessels of the retina.
A laser with a low power (a cold laser) is used. When exposed to the laser, Viudyne seals off the leaking vessels. Since it does not stay in the healthy retinal cells, they do not react to the laser and are not damaged.
However, since the photoreactive material remains in the body for several days, patients must stay out of the sun and cover up carefully on their trip home from the ophthalmologist or they will get a severe sunburn. Otherwise, few side effects or complications have been reported and the treatment can be successful for selected patients.

Laser Photocoagulation for Age-Related Macular Degeneration

Laser photocoagulation is a type of laser surgery that uses 

an intense beam of light to burn small areas of the 

retina and the abnormal blood vessels beneath themacula.

 (See a picture of the eye camera.) The burns form scar 

tissue that seals the blood vessels, keeping them from 

leaking under the macula. By sealing the leaky blood 

vessels, laser photocoagulation slows down:

  • The buildup of fluid under the retina that distorts the shape 

  • and position of the macula.

  • The growth of scar tissue and the abnormal membrane 

  • under the retina, both of which damage the cells in the 

  • macula.

  • Central vision loss.

Laser surgery may be done in a doctor's office or eye clinic 

using a local anesthetic that affects only the eye 

area. The surgery itself is painless. But your eye may hurt 

slightly after the surgery.

Anti -VEGF Treatment 

The latest development for treating Exudative ARMD are specific drugs which target a specific chemical that is critical for causing abnormal blood vessels to grow under the retina .This chemical is called Vascular Endothelial Growth Factor (VEGF).Anti -VEGF drugs block the trouble causing VEGF ,reducing the growth of abnormal vessels and slowing their leakage.

5 टिप्‍पणियां:

Aziz Jaunpuri ने कहा…

बेहतरीन प्रस्तुति ज्ञान संवर्धन में योगदान देकर सराहनीय कार्य किया है , सर जी

रविकर ने कहा…

जी आदरणीय-

डॉ टी एस दराल ने कहा…

Nice Article. Useful information.
Floaters are also sign of MD though occasional ones are normal in healthy individuals .

दिगम्बर नासवा ने कहा…

ये तो बिलकुल नई सी जानकारी है ... पर है तो बहुत उपयोगी जानकारी ...
शुक्रिया जी ... राम राम जी ...

Kailash Sharma ने कहा…

बहुत उपयोगी जानकारी...