Changes in choroidal thickness and corneal parameters in diabetic eyes

To evaluate the effect of diabetes mellitus (DM) on central corneal thickness (CCT), corneal endothelial parameters (endothelial cell density [ECD], average size [AVE], hexagonality [A6], polymegathism [SD]), and subfoveal choroidal thickness (SFCT), and to determine whether these parameters depend on the duration of DM and hemoglobin A1c (HbA1c) level.

A total of 62 patients with type 2 DM and 65 healthy subjects were examined using a noncontact specular microscope, A-scan ultrasound, and spectral-domain optical coherence tomography. The study parameters included medical history, age, eye axial length, CCT, ECD, AVE, A6, SD, and SFCT. The duration of DM and HbA1c level of the 2 latest tests were noted.

The SFCT (258.0 ± 74.4 µm) and ECD (2721.8 ± 264.1 cells/mm2) were significantly lower, and the CCT (566.7 ± 35.7 µm) higher, in diabetic patients than in the control group (313.1 ± 88.5 µm, 2967.3 ± 220.6 cells/mm2, 550.0 ± 56.4 µm, respectively) (p<0.05). There were no differences in age, sex, or axial length between the diabetic and control groups (p>0.05). Diabetic retinopathy and macular edema did not influence SFCT significantly (p>0.05). No differences in endothelial parameters between groups and no correlations among HbA1c, duration of DM, and any of the examined parameters were found (p>0.05).

Diabetic patients have thicker corneas, lower ECD, and thinner subfoveal choroid than healthy subjects.