The Pathogenesis of Index Myopia in Hyperglycemia in Type 2 Diabetes: A Review

Abstract

Elevated blood glucose or hyperglycemia occasioned by Diabetes Mellitus (DM), compromises the index of refraction of the crystalline lens, due to the osmotic difference between the lens materials and the aqueous medium of the anterior chamber of the eye. Under this circumstance there is a movement of fluid to either direction depending on the concentration gradient in both media. When there is movement out of the lens, into the aqueous, the refractive index of the lens increases, and this situation also causes a sudden change in the refractive power of the lens, leading to index myopia, while a decrease leads to index hyperopia. However, the induced myopia from this sudden fluctuation in the refractive power of the crystalline lens reverses shortly after a prolonged treatment and control of the hyperglycemia, with a combination of hypoglycemic drugs and diet therapy by the physician. The Issuance of spectacle prescription during these fluctuations is suspended until reversal.