Conjunctival Microangiopathy in Diabetes Mellitus Assessed with Optical Coherence Tomography Angiography

To detect and quantify conjunctival microangiopathy with optical coherence tomography angiography (OCTA).

Imaging was performed in the temporal and nasal quadrant of the conjunctiva using a Heidelberg Spectralis spectral domain-OCT in OCTA mode adding a 25D lens to the standard 30° fundus lens. Images were acquired within a 10° × 5° cube at the limbus. Binary images were analyzed using ImageJ (Fiji software version 2.0) and an average relative conjunctival vessel density was assessed.

Thirty-two patients with diabetes mellitus type 1 and 2 and 42 healthy individuals were included. Vessel density in healthy individuals was 16.7 ± 5.2% in the nasal and 17.9 ± 6.4% in the temporal quadrant. In patients with diabetes without retinopathy, vessel density was 16.3 ± 6.7% in the nasal and 15.3 ± 7.3% in the temporal conjunctiva. In patients with diabetic retinopathy, vessel density was 13.7 ± 4.3% in the nasal and 15.2 ± 6.5% in the temporal conjunctiva. There were statistically significant higher values in both nasal and temporal measurements among healthy individuals than in patients with diabetic retinopathy (P = 0.03 and P = 0.01, respectively).

Patients with diabetic retinopathy exhibit reduced vessel density, which may suggest diabetic microangiopathy in the conjunctiva. Anterior segment OCTA may detect conjunctival microangiopathy in patients with visual axis opacifications, where retinal OCTA is not possible.

The findings of this study bridge the gap between experimental anterior segment OCTA imaging and clinical screening for diabetic complications.