Evaluation of Corneal Sensitivity and Quadrature Variability in Patients with Diabetic Neuropathy.

Purpose: The purpose of the study was to evaluate the corneal sensitivity and its quadrature variability in patients with diabetic neuropathy (DN) diagnosed with electromyography and to compare these results with age- and sex-matched healthy individuals.

Methods: The left eyes of 32 patients who applied for refraction or fundus examination and had a diagnosis of DN by electromyography in their medical history were included in this study. Corneal sensitivity was evaluated using the Cochet-Bonnet esthesiometer (Luneau, Paris) in five zones: central, nasal, superior, temporal, and inferior. The measurements of the patients were compared with the measurements of 32 age- and sex-matched healthy volunteers. Furthermore, the measurements of five corneal zones were compared with each other, and the level of correlation was investigated in each group.

Results: The central corneal sensitivity values were measured as 4.12 ± 1.04 (mm) and 5.92 ± 0.14 (mm) (P < 0.001). While the sensitivity values at the superior, inferior, nasal, and temporal quadrants were detected as 5.85 ± 0.21, 5.85 ± 0.26, 5.94 ± 0.13, 5.93 ± 0.13, and 5.92 ± 0.14 (mm) in the control group, it was measured as 3.67 ± 0.66, 3.67 ± 0.62, 3.67 ± 0.62, and 3.89 ± 0.73 (mm) in the DN group, respectively. The corneal sensitivity values were all found to be significantly lower in the DN group (P < 0.001 for all parameters) at all quadrants as well as the central cornea. Furthermore, a moderate positive correlation between all five zones in the control group and a very strong positive correlation in the DN group were found in terms of the corneal quadrature sensitivity.

Conclusion: The current study revealed a significant reduction in corneal sensitivity in patients with DN. In both the control group and DN group, all corneal zones showed positive correlations which show the consistency of the measurement in different quadratures. Evaluating corneal sensitivity with a Cochet-Bonnet esthesiometer might serve as a useful screening tool in detecting neuropathy development. By taking the necessary precautions, further damage can be prevented.