Analysis of tear meniscus and anterior segment alterations in keratoconus patients after scleral contact lens

PURPOSE: The objective of the study is to evaluate the effects of scleral contact lenses (ScL) wear on tear meniscus parameters and anterior segment changes in patients with keratoconus (KC).
METHODS: This prospective study included 37 eyes of 23 KC patients fitted with ScLs (ICD FlexFit scleral lens, ABB Optical Group, USA). Best-corrected visual acuity (BCVA) and lens fitting parameters were assessed. Tear meniscus depth (TMD), tear meniscus area (TMA) and tear meniscus height (TMH) were evaluated using anterior segment optical coherence tomography (AS-OCT) along with anterior chamber depth (ACD), anterior chamber angle (ACA), anterior chamber volume (ACV), pupil diameter, and central corneal thickness (CCT) were measured before lens application and after 4 h of wear using corneal topography.
RESULTS: According to the ABCD classification, 25 eyes were Stage 1, 9 eyes were Stage 2, and 3 eyes were Stage 3. The fitted ScLs had an average vault of 4369±453 μm, an average diameter of 16.1±0.37 mm, and a mean base curve of 7.64±0.71 mm. BCVA improved significantly after ScL from 0.25±0.11 to 0.018±0.05 logMAR. The mean tear reservoir thickness was 315±50 μm. Although no statistically significant changes were observed in parameters such as ACA, ACD, ACV, and CCT, a significant reduction in TMH, TMD, and TMA values was observed after lens wear (p<0.001).
CONCLUSION: ScLs are an effective treatment option to improve visual quality in patients with KC. Although scleral lenses have no direct contact with the cornea, TMH decreased within hours of wear. Changes in anterior segment parameters, as well as lens fitting, can be evaluated using AS-OCT and corneal topography.

Keywords: Anterior segment parameters, meniscus height, scleral contact lenses, tear fluid reservoir, tear meniscus depth, tear tear meniscus area