SCI-TECH & AGRI

Saving sight through reach and research

THE DAWNING of the new millennium in the year 2000 made many governments and agencies sit up and think about approaches to manage and solve some long-standing problems. Vision 2020 was a favorite title used for such plans. The goal, as the term indicates, is to set up a deadline of 20 years within which the task should be completed. Of the many Vision 2020s, one that captures the heart, both for its urgency and credibility, is the one by the International Agency for the Prevention of Blindness (IAPB). The IAPB is a global initiative that includes the WHO, multinational aid agencies and many national and provincial governments. Its aim is simple and striking: to prevent all forms of blindness that are preventable and avoidable, by the year 2020. IAPB is working with the full realization that the clock is ticking and will run out in 18 years.

Its task is doable because of the simple fact that 80 per cent of the blindness burden in people across the world is due to three major causes, number one is cataract, a condition in which the eye lens is progressively clouded, leading to loss of vision. Today there are more than 9 million people in India who are cataract-blind. Left untreated, this number will rise to 14 million by the year 2020. A simple operation that takes less than 20 minutes, and costing but a few hundred rupees, restores eyesight safely and successfully. There are today about 10,000 eye doctors across the nation. If each of them does but 10 cataract operations per day for 100 days of the year, the cataract burden is lifted. What is needed is thus a systems approach, which on one hand increases the number of cataract surgeons and on the other, distributes their services evenly across the country so that everyone is accessed. This is precisely what is being planned by IAPB, in collaboration with agencies and services groups across the nation.

The second form of preventable blindness is too shocking to even mention. Today, there are 3 million Indians (one in every 333) who cannot see simply because they do not wear (or cannot afford) corrective eyeglasses. They are blind because of refractive errors in their eyes - a condition that is set right in 10 minutes. An optometrist can determine the `power' or diopter value needed to make their vision normal and prescribe spectacles. To allow this form of blindness to continue is pathetic and inexcusable. Here again, if the issue is not addressed, the number of refractive error- blind in India will climb to 4.5 million. IAPB is working towards eliminating this form of blindness burden with the help of NGOs, self-help agencies and governments. The programme called `Village Vision' is a remarkable example. Inspired by the Bangladesh based `Grameen Bank' idea of steering microcredit to village women, this program offers eye glasses on credit to a village women; each of them sells it at a price that helps her pay back the loan and make a small profit.

The third form of preventable blindness is infection of the eye by bacteria, viruses, fungi and parasites. About, one in every 1000 Indians suffers from such infections, which if left untreated for a while, leads to blindness. A bit of cleanliness and of course antibiotic eye drops applied early enough will totally solve this problem.

IAPB's Vision 2020 has a focusing subtitle `The Right to Sight'. This insistent phrase clubs sight as a human right quite like the right to express ideas, to vote and to good health. Clearly, the goals set forth one achievable, with the systems approach adopted and with the participation of all `stakeholders'. It could thus lead to `Sight Revolution' just as we have had the `White Revolution' through a similar commitment and plan of action.

What of the rest 20 per cent blindness burden? They need inputs from basic research on one hand and technological advances on the other. Interaction between clinicians and basic researchers is vital, and can lead to innovative approaches. Such a fusion, published in the May 2002 issue of Archives of Ophthalmology, promises to be innovative and useful in treating glaucoma, the fourth important blinding disease.

The paper, involving colleagues from the LV Prasad at Hyderabad, Aravind Eye Hospital in Madurai, Weizmann Institute at Rehovoth, Israel, George Washington University at Washington, USA and University of Rochester ophthalmology department at Rochester, NY, USA, reports preliminary results of a trial of a new approach to glaucoma surgery. It spares the surgeon from going inside the eye (non-penetrating), is technically simple and promises to be much less expensive than currently practiced methods of glaucoma surgery. All these three points are of value to economically developing nations, where glaucoma hits about 10 per cent of the people, and where the technical requirements of man and machine are not very easy to obtain all over.

Glaucoma results due to an increased pressure within the eyeball. Nutrition to the eye largely comes from the rest of the body in the form of liquid diet. This vital liquid filters into the eyeball through the ciliary body, a muscular strut spanning the globe.

The exit pathway is via a sieving system called the trabecular meshwork, and through tiny channels back into the bloodstream. In effect, the eye is a water balloon in which aqueous humor is continually siphoned. If the siphon is blocked, pressure builds. The optic nerve in the back of the eye is pressed out of service, leading to loss of vision. Pressure can build because the filtering mesh outlet is in trouble, or the pipe through which the fluid flows is pinched (the `angle'closure is acute or too open).

The glaucoma surgeon has to be at once a plumber and a cobbler. She first measures the pressure within the eyeball (she has to, in order to decide how high it has climbed beyond normal; the patient may feel the pressure as pain, as reduced vision and through the white ring in the eye or may feel nothing at all until one day it hits after all the silence). Then she determines whether the angle is too acute, or alternately it is an open angle case and plans to unclog the siphon.

Of the two, angle closure is easier handled. However, the open angle glaucoma is equally prevalent in India, and higher in the West. It is in handling this surgery that an innovative idea has been tried out by the trinational group. They have used a natural protein `knife' that can shave off (or digest) the required amount of tissue, so that the aqueous humor can now percolate through. The flow-off of aqueous humor would increase, pressure within the eye would drop and relief obtained to the patient.

The Israel colleagues argued that thinning of the tissue can be done using the enzyme collagenase, thereby improving the drainage of the aqueous humor. This idea was first tried on rabbits as model and was found to work. The Indian group was excited at this result, and offered to try it out on humans. The Madurai group devised a safe and effective way to place the enzyme in an applicator at the appropriate position within the eye, and remove it after a day. The Hyderabad group tried it on 15 humans, on their glaucoma blind eyes, in order to check whether this method (tongue-twistingly named as enzymatic sclerostomy) lets the pressure drops and symptomatic relief obtains.

It does. The editors of Archives of Ophthalmology felt sufficiently enthused to write a complimentary editorial on the introduction of this innovative concept with potential use. Lest patients come running in demanding enzymatic sclerostomy, the doctors point out that it is still in the very early and experimental stage.

The first trial was done in 1998 and the second now, both at Hyderabad. We need to go much ways, improving every aspect of the method before it can be confidently recommended. The procedure need to be improved how much enzyme, how long, which applicator, how to adopt it to individual eye shape and size, what can be recommended as the standardized procedure and so on.

But as Confucius said every major journey starts with a single step. That has been taken. May we wish luck and greater success to Drs. J.A.Dan, S.G.Honavar, D.A.Belyea, A.K.Mandal, G.Chandrasekhar, B.Levy, R.Ramakrishnan, R.Krishnadas, M.F.Liebeman, R.L.Stamper and A.Yaron?

D.Balasubramanian

L.V.Prasad Eye Institute

Hyderabad - 500 034

Recommended for you