Confocal Microscopy of the corneal sub-basal nerve plexus and anterior stroma in Sjögren's syndrome associated dry eye disease

Abstract

Purpose: To describe the morphological features of the sub-basal nerve plexus area and anterior stroma in patients with dry eyes associated with Sjögren's syndrome (SS) by using in vivo confocal microscopy (IVCM).

Methods: Central cornea images were prospectively captured from 43 eyes with clinically diagnosed Sjögren's syndrome and 10 age matched healthy control eyes using In Vivo Laser Scanning Confocal Microscopy (Heidelberg Retina Tomograph Rostock Cornea Module - HRT III RCM). Parameters of the sub-basal nerve plexus (density, tortuosity and reflectivity), epithelial dendritic cell density and morphological changes of the anterior stroma were evaluated. The nerve density analysis was performed using the semi-automated tracing program NeuronJ, a plug-in for ImageJ. The nerve tortuosity and nerve reflectivity were classified in four grades according to previously validated grading scales. The dendritic cell density in each visual field (400 x 400 µm) was determined using the semi-automated cell count provided by the microscope.

Results: Images obtained by IVCM from 53 eyes were analyzed. The evaluation of the sub-basal nerve plexus in SS eyes demonstrate significant reduction in density (1561.7±995.5 vs. 2724.8±687.06 µm/frame, p<0.001), increased tortuosity (2.78±0.7 vs. 2.23±0.5, p<0.05) and decreased reflectivity (2.76±0.7 vs. 3.5±0.5, p<0.01). IVCM was able to detect an overall elevated dendritic cell density within the corneas of eyes affected with SS (64.9±70.6 vs. 27.5±5.5 cells/mm², p<0.01). In SS dry eyes as compared to normal controls, the keratocytes within the anterior stroma also demonstrated evidence of abnormal hyper-reflectivity.

Conclusions: IVCM reveals morphological changes in the corneas of patients with SS as compared to normal corneas. Our study demonstrated decreased corneal nerve density, increased tortuosity and decreased reflectivity of corneal nerves. These findings suggest the potential for use of IVCM in the evaluation and monitoring of patients with ocular manifestations of SS.