Effect of glycemic control on refractive changes in diabetic patients with hyperglycemia.

Purpose: To investigate the effect of intensive glycemic control on hyperglycemia- induced changes in refraction, corneal topography, lenticular and corneal thickness in diabetic patients.
Methods: Eighteen diabetic patients with plasma glucose >300 mg/dl were enrolled in the study consecutively. Autorefraction, C-Scan corneal topography, Javal keratometry, corneal pachymetry and ultrasonic biometric measurements were carried out at presentation and after metabolic control of blood sugar (plasma glucose profile <200 mg/dl). One eye of each patient was selected randomly for statistical analysis.
Results: Mean plasma glucose levels were 356.00 mg/dl before and 133.78 mg/dl after treatment. The median values of the autorefractometric measurements were - 0.125 D on admission and + 0.375 D at the second examination. The difference in the refraction was statistically significant (P = 0.022). Nine of 18 patients became hyperopic, 2 became myopic and 7 showed no change after treatment. There was a significant change in the corneal topographic keratometric measurements at the flattest corneal meridian after treatment (P = 0.037). After treatment no statistically significant changes were observed in the pachymetric corneal thickness, anterior chamber depth, biometric dioptric lens calculations and Javal keratometric data.
Conclusions: Hyperglycemia is the major cause of the transient refractive changes in diabetic patients. Following intensive medical treatment, a considerable number of patients tend to become more hyperopic compared with the hyperglycemic state. During the treatment period, changes in the corneal topographic parameters might be a potential source of error for keratorefractive and cataract surgery.