Correlation of Central Corneal Thickness and Keratometry Findings With the Severity of Diabetic Retinopathy and Glycosylated Hemoglobin (HbA1c) Levels in Type II Diabetes Mellitus Patients.

introductionDiabetes today is a global health issue, posing a risk to several organ systems. Besides complications like cataracts, diabetic retinopathy (DR), glaucoma and refractive errors, anatomical parameters like central corneal thickness (CCT), which is a crucial indicator of corneal endothelium function and keratometry parameters, have also been noticed to be altered in diabetes. Variations in these parameters may affect the accuracy of applanation tonometry in measuring intraocular pressure. This study aims to investigate variations in CCT and keratometry across different stages of DR, as prior research has yielded inconsistent results. The study also intends to explore the relationship between glycosylated hemoglobin (HbA1C) levels and changes in keratometry and CCT. MATERIALS AND

methodsThis observational cross-sectional study was conducted from July 2022 to June 2024. A total of 204 subjects, aged 35-70 years, were included in the study. All participants were evaluated for DR, and those showing fundus findings were graded into five classes based on the Early Treatment Diabetic Retinopathy Study (ETDRS) classification. CCT, keratometry parameters (K1 and K2) and HbA1C levels were measured for all participants. The clinical parameters were correlated across different grades of diabetes mellitus and compared using Statistical Package for the Social Sciences (IBM SPSS Statistics for Windows, IBM Corp., Version 23.0, Armonk, NY) software.

resultsThe patient population consisted of 130 males (63.7%) and 74 females (36.3%). It was found that there was a trend indicating that the presence of DR increased with age, which was statistically significant (p=0.036). However, the differences in the mean duration of diabetes across DR groups were not statistically significant. Findings suggested that individuals with DR generally possess a higher CCT compared to the control group, particularly in the earlier stages of the disease, i.e. no DR and mild non-proliferative diabetic retinopathy (NPDR). However, as the severity of DR increases, the CCT tends to decrease slightly in moderate NPDR, severe NPDR, and proliferative diabetic retinopathy (PDR) stages. The study notes that the variations in CCT across these groups were not statistically significant (p-value of 0.29). The study also found that changes in corneal curvature, as indicated by keratometry values, were more pronounced in the proliferative stage of DR, with a statistically significant increase in k2 values of the left eye (p-value = 0.025). The study concluded that there was no statistically significant relationship between CCT and keratometry values of both eyes with HbA1c levels.

conclusionWhile there were some clear patterns, especially concerning age, most variations in ocular parameters were not statistically significant, suggesting that other factors might need an in-depth study in the development of DR and its correlation with ocular parameters. Similarly, while HbA1c has often been stated to be a prognostic factor in diabetes mellitus, significant correlations were neither noted with ocular parameters like CCT and keratometry, nor the stage of retinopathy.