Prosthetic replacement of the ocular surface ecosystem for corneal irregularity: Visual improvement and optical device characteristics

Abstract

To describe patterns of prescribing Prosthetic Replacement of Ocular Surface Ecosystem (PROSE) in irregular corneas and compare various components of lens design. Design: Retrospective, observational case series. 244 eyes of 173 patients with keratoconus (n=178), pellucid marginal degeneration (n=21), keratoglobus (n=6), following refractive surgery (n=19) and following keratoplasty (n=20) fitted with the PROSE device were retrospectively analyzed. Simulated keratometry value along the steep meridian (Steep-K) and anterior chamber depth (ACD) were measured using Scheimpflug imaging. Improvement in visual acuity and parameters of lens design such as vault, front surface eccentricity (FSE) and toricity were analyzed and compared across all conditions. PROSE improved visual acuity, both uncorrected (median, 1.30 logMAR) and spectacle-corrected (median, 0.60 logMAR), to a median of 0.22 logMAR. Positive correlation was observed between Steep-K and ACD with lens vault, especially in keratoconus. Multiple regression analysis established ACD as the most reliable factor while choosing vault. FSE value of 0.6 was the most common across diagnostic subgroups. The distribution of FSE values did not differ between keratoconus patients with Steep keratometry of <60D or those >60D. In every diagnostic subgroup, at least 20% of eyes required a lens design of with-the-rule toricity of haptic. The PROSE device resulted in significant improvement in vision in this population. A trend of prescribing higher lens vault with increased keratometry value was evident especially in keratoconus. ACD appeared to be more important than Steep K in vault selection. An FSE of 0.6 and vertical peripheral lens toricity were used most frequently in this subset of patients.