Full-Time Wear of Prosthetic Replacement of the Ocular Surface Ecosystem (PROSE) Device Does Not Alter Endothelial Cell Density or Morphology

Abstract

Purpose: Corneal edema is a potential consequence of PROSE wear. This study investigated whether constant corneal immersion in the fluid-filled reservoir of the PROSE device could be causing a decrease in endothelial cell density or change in morphology that could account for this complication.

Methods: Patients referred for the PROSE device at Weill Cornell Medical College who had achieved wear of 6+ hours per day were included. Exclusion criteria were patients with epithelial defects or active intraocular inflammation. 12 patients (23 eyes) were included with an average of 113 days of wear. During the initial PROSE fitting session, images of the endothelium were obtained using a ConfoScan 4 (Nidek) confocal scanning microscope, and NAVIS software was used to calculate the endothelial cell density, pleomorphism, and polymegathism from triplicate images of the endothelium. Further endothelial confocal images were taken at 2-week intervals. A mixed model was run adjusting for two eyes per patient with a compound symmetry covariance structure for each outcome to test for differences between baseline and after full-time PROSE wear. A Pearson’s test was conducted to test for an association between change in endothelial cell density and days of full-time PROSE wear.

Results: The mean endothelial cell density at fitting was 2453 ± 93 and decreased to 2417 ± 89 cells/mm² by the final measurement (p = 0.27). Polymegathism changed from 38.9 ± 2.0 to 40.7 ± 2.1% (p = 0.45), and pleomorphism changed from 55.3 ± 1.9 to 50.4 ± 2.3% (p = 0.13). Over the time period covered, none of these changes in the endothelium were statistically significant. There was no significant correlation between a change in endothelial cell density and days of full-time PROSE wear (r = -0.05, p = 0.59).

Conclusions: Endothelial cell density, the heterogeneity of cell size (polymegathism), and the percentage of hexagonal endothelial cells (pleomorphism) are not significantly affected by PROSE wear over an average of 113 days. The corneal edema that arises during the PROSE fitting process may be due to processes other than endothelial cell dysfunction.

Keywords: 479 cornea: clinical science • 481 cornea: endothelium • 477 contact lens