Noninvasive, in vivo, high-resolution investigation of conjunctival vessels in diabetes and hypertension patients

PURPOSE: Vascular changes are key pathological features in many diseases, such as hypertension and diabetes. This study aimed to investigate the morphological changes of bulbar conjunctival vessels in hypertension and diabetes using laser scanning confocal microscopy (LSCM). METHODS: Patients with hypertension, diabetes, co-occurrence and age-matched control were recruited. Temporal bulbar conjunctiva 3-5 mm away from limbus was imaged using LSCM. The vessels were classified as arteries or veins. The wall-lumen thickness ratio (WLTR) and wall-lumen reflectivity difference (WLRD) were compared among different groups. Multivariant linear regression was used to assess the predictors of conjunctival parameters. RESULTS: A total of 93 eyes of 93 patients were included. The WLTR of conjunctival arteries in diabetes group (0.66 ± 0.22) and co-occurrence group (0.76 ± 0.41) were higher than in control group (0.48 ± 0.15). The WLRD of conjunctival arteries in co-occurrence group (66.68 ± 25.48) was higher than in control group (45.21 ± 23.40) and hypertension group (51.91 ± 24.75). The WLTR of conjunctival veins in co-occurrence group (0.43 ± 0.21) was higher than in control group (0.28 ± 0.11). No significant difference was found in vein WLRD among the groups. In multiple linear regression, diabetes and hypertension were associated with artery WLTR, vein WLTR and artery WLRD, but no factor was associated with vein WLRD. CONCLUSIONS: LSCM provides in vivo, noninvasive, high-resolution imaging of morphological changes in conjunctival vessels. Both hypertension and diabetes increase the WLTR of conjunctival artery and vein, as well as the WLRD of conjunctival artery but not the vein.