Comparison of Intraocular Pressure with and Without Central Corneal Thickness Correction in Diabetics

Abstract

Aim: To determine intraocular pressure with and without central corneal thickness correction in individuals with diabetes.

Study Design: This was a cross-sectional study conducted on diabetic patients.

Duration and Setting of the Study: The study was conducted over a period of six months, from May to October 2025, at Isra University, Karachi.

Methods: A total of 203 diabetic patients aged 30-75 years were selected through a non-probability convenience sampling method. Intraocular Pressure (IOP) was evaluated in both eyes with a Goldmann applanation tonometer, and Central Corneal Thickness (CCT) was determined using pachymetry. Patients aged less than 30 years, contact lens wearers, and those with hazy media were excluded. Data was analyzed using SPSS version 20. Bar charts and pie charts were used to describe qualitative data, while range, mean, and Standard Deviation (SD) were used to express quantitative data. Normality was assessed using the Shapiro–Wilk test. Paired t-tests were applied to compare IOP before and after CCT correction. Statistical significance was set at p < 0.05. Effect sizes were also calculated.

Results: A total of 203 patients were examined during the study in the age range of 30 to 75 years. Out of 203 patients, 118 were male and 85 were female.  Mean IOP before CCT correction was 12.42 ± 1.30 mmHg (right eye) and 12.33 ± 1.27 mmHg (left eye). After correction of CCT, mean IOP was 13.91 ± 2.82 mmHg (right eye) and 13.58 ± 2.75 mmHg (left eye) calculated using Ehlers’ formula. Mean differences were +1.49 mmHg (right eye) and +1.25 mmHg (left eye). These increases were statistically significant (p < 0.001).

Conclusion: After CCT correction, intraocular pressure showed a statistically significant increase. Pachymetry should be considered essential for accurate IOP assessment in diabetic patients.