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RESEARCH PRODUCT

Corneal thickness differences between type 2 diabetes and non-diabetes subjects during preoperative laser surgery examination

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Aims To evaluate the differences in corneal thickness between type 2 diabetes subjects with HbA1c under 7.0% and non-diabetes subjects during their preoperative laser surgery examinations. Methods The mean of five consecutive corneal thickness measurements at the central and mid-peripheral cornea was obtained by means of noncontact scanning-slit corneal topography (Orbscan Topography System II; Orbscan, Inc., Salt Lake City, UT, USA) in 35 myopic non-insulin dependent type 2 diabetes subjects (17 males and 18 females) and 48 healthy myopic controls (23 males and 25 females). Results The corneal thickness values at the central and mid-peripheral cornea were significantly higher in the diabetic group (p < .001). The diabetic subjects presented the highest thickness value in the superior cornea (n = 22; 62.9%) followed by the nasal (n = 9; 25.7%) and the temporal (n = 4; 11.4%) cornea, but never in the inferior cornea. The control subjects presented the highest thickness value in the superior cornea (n = 19; 39.6%) followed by the nasal (n = 18; 37.5%), the inferior (n = 6; 12.5%), and the temporal (n = 3; 6.3%) cornea. The central corneal thickness (CCT) of the diabetes patients was not statistically correlated with their HbA1c (r = .078; p = .104), body mass index (r = .007; p = .633), and time from diagnosis of diabetes (r = .025; p = .363), but it was correlated with their corneal endothelial cell density values (r = .543; p < .001). Conclusions Diabetes subjects with HbA1c under 7.0% who are candidates for laser refractive surgery present thicker corneas than their age-matched control subjects. In these patients, there is a correlation between their CCT values and their corneal endothelial cell density values, so when higher CCT values were found, lower corneal endothelial cell density values were observed.