Topical aldose reductase inhibitor.

amblyopia: a comprehensive survey of outcome. Eye 1992; 6: 300-4. 7 Lithander J, Sjorstrand J. Anisometropic and strabismic amblyopia in the age group 2 years and above: a prospective study of the results of treatment. retinoscopy by used to screen infants for amblyopia? A longitudinal study of refraction in the first year of life. Polymegathism is a term used to describe increased variability in the size of corneal endothelial cells. Polymegathism came to notice when the advent of the clinical specular microscope made the close examination of the corneal endothelium a relatively simple clinical procedure. With the addition of digital morphometric analysis systems to clinical specular microscopes, quantification of variations in cell size and shape also became simple and reliable. Polymegathism and pleomorphism (increased variability in cell shape) occur with age,1-3 after trauma (including cataract surgery),4 5 with contact lens wear,6-10 with a number of disorders affecting the anterior segment of the eye,'1114 and after keratorefractive procedures.15-17 They also occur in diabetes. 18-20 Polymegathism is often seen in diabetics when no other ocular disease is apparent. The precise mechanism is yet to be determined. It has been attributed to the accumulation of sorbitol in endothelial cells which in turn has been linked to the presence in corneal endothelial cells of aldose reductase, the rate limiting enzyme in the polyol pathway associated with the conversion of glucose to sorbitol.21-23 In addition to corneal endothelial cells, the enzyme is present in the lens and the retina.24-26 Experiments in diabetic animals have implicated sorbitol accumulation with osmotic changes and the development of cataracts.27 28 A similar process is proposed to explain irregularities in the size of corneal endothelial cells. When blood glucose levels are high, there is sufficient substrate for the polyol pathway to become important and for the intracellular osmolarity to rise and water to accumulate and alter cell size and shape. Whatever the mechanism, inhibition of aldose reductase reverses endothelial polymegathism.21 22 29 30 It has been demonstrated that galactose fed dogs developed polymegathism and that the concomitant administration of aldose reductase inhibitors prevented this.22 Furthermore, it has also been shown that topical administration of aldose reductase inhibitors could reverse polymegathism in animals.2' 23 29 30 More recently it has been shown that corneal epitheliopathy and decreased sensation in human diabetics can be reversed using the same therapeutic approach.31 32 The paper by Ohguro et al in this issue of the …