Efficacy of Rose-K lens in enhancing visual acuity and contrast sensitivity in keratoconus

Background: Keratoconus is a progressive, noninflammatory corneal ectasia that is characterized by corneal thinning and conical deformation, which leads to irregular astigmatism, myopia, and reduced visual quality. As the disease progresses, spectacles often become inadequate, necessitating the use of rigid gas-permeable or specialty contact lenses to restore vision. Traditional evaluations rely on high-contrast visual acuity tests, which alone do not capture functional vision impairments. A more comprehensive assessment includes contrast sensitivity (CS), a key predictor of real-world visual performance. The ROSE K2 XL semi-scleral lens offers tailored optical correction for irregular corneas. We investigated its efficacy in enhancing best-corrected distance visual acuity (BCDVA) and CS in patients with keratoconus. Methods: In this prospective study, we recruited adults with varying keratoconus severities from the Armed Forces Hospital in Oman, between February and December 2024. The patients were fitted with ROSE K2 XL semi-scleral lenses to assess changes in BCDVA and CS. Participants who had undergone prior ocular surgery (except for corneal crosslinking) or who had other corneal pathologies were excluded. Baseline and post-fitting BCDVA were measured using a crowded Keeler logarithm of the minimum angle of resolution (logMAR) chart. CS was assessed using the Pelli–Robson chart under standardized photopic conditions. Keratoconus severity was graded using the Amsler–Krumeich classification system. All examinations were performed by the same experienced optometrist to ensure consistency and to reduce measurement variability. Results: We enrolled 180 eyes from 90 participants with keratoconus (mean [standard deviation, SD] age: 29.2 [5.4] years; 65.6% [n = 59] female). Disease severity was classified as follows: stage I (n = 16, 8.9%), stage II (n = 52, 28.9%), stage III (n = 70, 38.9%), and stage IV (n = 42, 23.3%). After ROSE K2 XL lens fitting, the mean (SD) BCDVA improved significantly, from 0.90 (0.48) logMAR to 0.10 (0.11) logMAR (P < 0.001). The mean (SD) CS also increased significantly, from 0.96 (0.47) log CS to 1.90 (0.16) log CS (P < 0.001). Significant improvements in BCDVA and CS were observed across all disease stages (all P < 0.001), with the most pronounced gains found in cases of advanced keratoconus (stage IV). Conclusions: Fitting ROSE K2 XL semi-scleral contact lenses in patients with keratoconus resulted in significant improvements in both BCDVA and CS across all disease severity levels. These findings show the clinical value of semi-scleral lenses for visual rehabilitation of keratoconus, particularly in the advanced stages, where conventional spectacles or lenses may offer limited benefits. Incorporating CS assessment with visual acuity evaluations provides a more comprehensive investigation of real-world visual function, supporting evidence-based lens selection to optimize patient outcomes. Future studies should explore the long-term effects of these lenses on corneal physiology and patient-reported quality of life.