Sight for Sore eyes: a bright spot in an otherwise dismal prognosis for sub-Saharan Africa: Simple measures against trachoma, a bacterial infection that causes deformed eyelids, are saving the vision of millions

Natural History, Dec, 2004 by Zingeser James A.

News from the Republic of the Sudan seems to be relentlessly grim. Just one year ago, there was real hope that one of the world's longest-running civil wars was about to end. Negotiations between the Sudan People's Liberation Army and the Khartoum government were going well, and Ugandan rebels operating in the south, along the Uganda-Sudan border, were on the run. Then, in 2004, the peace talks stalled as a bloody conflict exploded in the Darfur region, in the west; meanwhile the rebels continued their terrorist activities in the south. All of this in Africa's largest country, where the harsh environment--from the Sahara in the north to the tropical swamplands of the south--helps to lock millions of people in an infernal cycle of poverty and disease.

The vast majority of Sudanese live in a state of extreme deprivation and are terrorized by an appalling array of infectious maladies, most of which they are ill prepared to combat. Yet, they struggle on, and not without reason for hope: many diseases that have brought misery to millions for centuries turn out to be treatable and even preventable by the smart and dedicated application of modern medicine and public health.

Recently, in the heat and pounding rains of Malakal, a town in southeastern Sudan, a tall, elderly woman guided by a child approached a Sudan Trachoma Control Program team for help. The woman bore decorative facial scars--testimony of her Shilluk tribal heritage. She also bore other scars that testified to a life of poverty and neglect--the scars of trachoma. Both of her eyes were leathery and completely white, with no visible corneas or pupils. The program nurse gently spoke with her in Shilluk to explain that surgery might relieve some of her pain, but could not restore her vision. For this woman, the campaign to eliminate this blinding disease had arrived too late.

But blindness from trachoma is completely preventable, and the Sudan campaign brings hope that today's children may grow up free from such devastating effects.

Trachoma is an infection caused by certain strains of the bacterium Chlamydia trachomatis. The symptoms first appear as conjunctivitis, an inflammation of the conjunctiva, the layer of tissue that lines the inside of the eyelids and extends over the adjacent edges of the eyeball up to the margins of the cornea. In its earliest stage, most commonly seen in boys and girls under the age of ten, it looks at first like an unremarkable case of "pink eye." Close examination of the soft tissue inside the upper eyelids, however, reveals follicles--round whitish, pinhead-size aggregations of lymphoid cells that have gathered to fight off invading bacteria--that are characteristic of the disease.

That stage may lead to intense inflammatory trachoma, in which the conjunctiva becomes noticeably thickened, and small blood vessels within it become engorged, making it progressively redder. For reasons still unclear, as many as 10 percent of patients go on to develop severe, chronic stages of trachoma. With repeated bouts of infection, scars develop on the inner side of the eyelids, and as the scars constrict, they pull inward on the skin around the margins of the eyelids. The constriction of the skin rotates the eyelashes progressively closer to the cornea. The condition in which the eyelashes are permanently turned inward, so that they actually touch the eyeball, is called trichiasis. When the inturned lashes grate on the cornea, the trichiasis is painful and dangerous.

One obvious and traditional treatment is simply to pluck out the offending eyelashes. But that turns out to be a poor way to treat the problem, because it leads to short, broken eyelashes that are even more abrasive to the cornea. The body then "repairs" the damaged cornea with opaque scar tissue, which blocks light from entering the eye. If scarring blocks a substantial part of the pupil, the opening to the interior of the eye, the result is permanent blindness. Blindness from trachoma is not treatable, not even in the best of circumstances, because the tissue and blood supply around the cornea are so severely damaged that a corneal transplant would have a high risk of failure. As bad as that is, the blinded person still gets no relief from the pain, because the inturned eyelashes continue irritating the cornea.

Apart from being a personal tragedy, trachoma can spell disaster to families or even entire communities in regions where trachoma is highly endemic, such as sub-Saharan Africa. Children with impaired vision may not be able to attend school or do household chores. Sighted children are frequently needed as caretakers; in afflicted communities they are often seen guiding blind adults instead of attending school. Blinded adults can do only limited kinds of work; they can contribute little to farming or childrearing.

Trachoma is most widespread in sub-Saharan Africa, but it is also a serious problem in the Middle East, Central Asia, and Southeast Asia. Pockets of the disease also occur in impoverished areas of Latin America and even in Australia. Some 6 million persons have been blinded by trachoma, making it the world's leading cause of preventable blindness. The World Health Organization (WHO) estimates that some 150 million people are infected with the bacterium that causes the disease, and more than 500 million are at risk of infection.