Relationship between hyperglycemia and intraocular pressure, corneal biomechanics, and corneal topography during the oral glucose tolerance test in nondiabetic patients.

Purpose: Altered corneal biomechanics in patients with diabetes may affect intraocular pressure (IOP) measurements. Although a relationship between IOP and glucose levels has been reported in diabetic and nondiabetic patients, the mechanism by which hyperglycemia influences IOP is unclear. The aim of this study was to determine the effects of hyperglycemia on IOP, corneal biomechanics, and anterior segment parameters during the oral glucose tolerance test (OGTT) in nondiabetic patients.

Methods: Twenty-one patients without DM who underwent OGTT were included in this study. A complete ophthalmologic examination was performed before the test. Blood glucose, insulin level, IOP (iCare rebound tonometer), Ocular Response Analyzer, and corneal topography (Pentacam) measurements were obtained at 0, 1, and 2 h during the OGTT. Data from the patients' right eyes were included in the analysis.

Results: The mean age of the patients was 46.9 ± 11.0 years. There was a statistically significant difference in IOP between 1 and 2 h (p = 0.03) and a clinically significant difference between 0 and 1 h (p = 0.06). Corneal resistance factor was lower at 2 h than 1 h (p = 0.03), while central cornea thickness was increased at 1 h (p = 0.01) and 2 h (p = 0.05) compared to 0 h. There was positive partial correlation between hyperglycemia and IOP at 1 h (p = 0.049, r = 0.67).

Conclusion: The positive partial correlation between IOP and glucose level suggests that acute hyperglycemia may lead to increased IOP. However, further research is needed to explain the mechanism of IOP elevation in the hyperglycemic phase during OGTT.