Natural history of lens opacities in diabetics.

IT IS uncertain whether senile lens opacities are more frequent in diabetics than in nondiabetics (Andersen, 1925; Waite and Beetham, 1935; Heinsius and Arndt, 1950; Dollfus, 1954; Kato, Amaha, Hagai, and Matui, 1960; Tulloch, 1962), yet cataract extraction is undoubtedly commoner, by a factor of five times or so, in known diabetics than in nondiabetics (Caird, Hutchinson, and Pirie, 1964). The visual indications for cataract extraction do not differ in diabetics and non-diabetics (Caird, Hutchinson, and Pirie, 1965a). The simplest explanation for this disparity would be that maturation, which may be defined as the progression of opacities to the point where cataract extraction is indicated (Caird, Hutchinson, and Pirie, 1965b), is more rapid in diabetics. The present study is an attempt to define in quantitative terms some of the factors involved in the natural history of lens opacities in diabetics by an analysis of over 2,800 observations by ophthalmologists on the eyes of over 1,800 diabetics who have attended one clinic in the past 15 years. Material and Methods The patients studied were those attending the Radcliffe Infirmary Diabetic Clinic with a definite diagnosis of diabetes (Burditt, Caird, and Draper, 1968). Since 1949, ophthalmologists have regularly examined these patients, though only by ophthalmoscopy, no slit-lamp examinations having been made. The examinations are largely random, and the interval between them is usually between 2 and 5 years. An observation was considered valid for the purposes of the present study if there was a clear statement about both lenses. Patients with lens opacities thought to be congenital or traumatic in origin were excluded, but all other lens opacities of whatever nature were considered together. There were 2,820 valid observations on 1,827 patients, ofwhom 687 had more than one valid observation. The observations were classified as follows: Group 1. Both lenses normal; Group 2. Unilateral lens opacity with a view of both fundi; Group 3. Bilateral lens opacity with a view of both fundi; Group 4. Unilateral or bilateral lens opacity with no view of one or both fundi; Group 5. Unilateral or bilateral aphakia. Groups 2, 3, 4, and 5 are referred to together as "lens opacities", and Groups 4 and 5 together as "cataract". Control of diabetes was assessed from the "glycosuria percentage", that is, the proportion of routine urine tests at clinic attendances showing 2 per cent. or more glycosuria (Caird, 1967). Only patients with five or more attendances were considered; they were divided into those with a "glycosuria percentage" over the period in question of 19 per cent. or less, and those with 20 per cent. or more.