Corneal backscatter in insulin-dependent and non-insulin-dependent diabetes mellitus patients: a pilot study

Purpose: To compare central corneal backscatter obtained from Scheimpflug images between patients with insulin-dependent and non-insulin-dependent diabetes mellitus (IDDM and NIDDM, respectively) and healthy controls. Methods: Seven patients with IDDM (7 eyes), eleven patients with NIDDM (11 eyes), and sixteen healthy subjects (16 eyes) were included in this pilot study. Scheimpflug imaging system (Pentacam, Oculus Inc., Germany) was used to obtain optical sections of the cornea. Seven meridians were analyzed for each eye, oriented from 70 degrees to 110 degrees. Optical density values for the central 3-mm and 5-mm zones of the cornea were obtained by image analysis using external software. Results: Corneal backscatter was significantly higher in the diabetic patients than in the controls for the central 3-mm (p = 0.016) and 5-mm (p = 0.014) zones. No significant differences in corneal backscatter were found between the IDDM and NIDDM groups for either zone (both p > 0.05). In the NIDDM group, significant correlations were observed for both central zones between corneal backscatter and age (3 mm: r = 0.604, p = 0.025; 5 mm: r = 0.614, p = 0.022) and central corneal thickness (3 mm: r = 0.641, p = 0.017; 5 mm: r = 0.671, p = 0.012); this was not found in the IDDM group (p > 0.05). The presence of diabetes showed a significant effect on central corneal backscatter (Kruskal-Wallis test, p < 0.001). Conclusions: Diabetic patients showed higher values of corneal light backscatter than healthy subjects. Corneal optical density analysis may be a useful tool for monitoring and assessing the ocular changes caused by diabetes.