Special Lenses for the Poor-Sighted
Abstract
Contact Lenses. Many persons on the borderline of economic blindness can be helped by the use of special lenses. Keratoconus is one condition which has long been recognized, but for which treatment has not offered a good prognosis for improvement in sight. In recent years, however, contact lenses have been developed to help this condition, and in the past year even greater benefits have been obtained from the use of plastic contact lenses (Fig. 1).
Keratoconus as defined by Duke-Elder1 is “a condition which involves stretching of the cornea in an axial part becoming manifest usually in the youth or adolescent and resulting in a visual impairment owing to the development of a high degree of astigmatism. It is a non-inflammatory ectasia or in a sense an anterior myopia.”
The etiology of keratoconus is unknown. Most of our cases at the Clinic, however, have been associated with a definite allergy. In other cases a coexisting endocrine imbalance has been noted. One patient, a woman past 50, had normal vision ten years ago. A rccent examination following a thyroidectomy and subsequent hypothyroidism showed a definite keratoconus. In another case the condition occurred following pregnancy. In one case the condition occurred three months after the use of sulfathiazole.
Keratoconus is usually bilateral. Thirty-three of 39 cases seen at the Clinic, or about 90 per cent, were bilateral, and four cases were unilateral. To date, I have seen the condition only once in successive generations. This occurred in a father and daughter both. . .
