Abstract
Purpose:
To determine if PROSE wear causes changes in tear production, corneal sensitivity and corneal nerve morphology.
Methods:
All patients referred to Weill Cornell Ophthalmology for PROSE treatment were considered for the study. At one visit prior to PROSE device wear and at one visit after at least 30 days of uninterrupted PROSE wear (for at least 6 hours per day), the following measurements were taken: tear production using the Schirmer’s test with anesthesia (n = 9 patients, 17 eyes), central corneal sensitivity using a Cochet-Bonnet Aesthesiometer (n = 8 patients, 12 eyes), and corneal nerve morphology by confocal microscopy (ConfoScan 4, Nidek). A single best image showing nerves in the sub-basal nerve plexus (n = 6 patients, 8 eyes) and stromal nerves (n = 4 patients, 5 eyes) was chosen from each appointment. Images were analyzed for sub-basal epithelial nerve fiber length and tortuosity and stromal nerve trunk thickness using NeuroLucida Software (MBF Bioscience, Williston, VT). Sub-basal epithelial nerve density was calculated by dividing the total length of nerve fibers in each image by the area photographed. Tear production, central corneal sensitivity, sub-basal epithelial nerve density and tortuosity, and stromal nerve trunk thickness were compared before PROSE wear and after uninterrupted PROSE wear using a paired t-test.
Results:
Tear production significantly decreased from 17.5 ± 5.2 mm baseline to 13.3 ± 6.1 mm after at least 30 days of PROSE wear (p = 0.00098). In contrast, central corneal sensitivity increased significantly from baseline (46.3 ± 6.4 mm) after at least 30 days of 6 hours or more of PROSE wear (53.8 ± 7.7 mm; p = 0.010). Neither sub-basal epithelial tortuosity (1.075 ± 0.035 vs. 1.077 ± 0.049; p = 0.91), nor sub-basal nerve density (1711 ± 878 µm /mm2 vs. 1845 ± 707 µm/mm2; p = 0.70) were altered by PROSE wear. Stromal nerve trunk thickness decreased significantly from an initial value of 8.5 ± 2.3 µm to 4.7 ± 1.9 µm after wear (p = 0.038).
Conclusions:
Changes in tear production and corneal nerve parameter suggest that PROSE treatment may affect elements of the lacrimal functional unit. The PROSE device shields the ocular surface from its normal environment and may allow for functional changes in the neural output with a concomitant change in tear production.
Keywords: 479 cornea: clinical science •
486 cornea: tears/tear film/dry eye •
420 anterior chamber