Abstract: Objective To evaluate the effectiveness and short-term safety of scleral lenses in treating  keratoconus. Design Retrospective case series study. Participants Twenty-two patients (34 eyes) with keratoconus fitted with scleral lenses at the Beijing Tongren Hospital, Capital Medical University, including 12 patients (17 eyes) who completed one-month follow-up. Methods All patients underwent a standardized fitting process for scleral lenses. BCVA, spherical equivalent (SE), non-contact intraocular pressure (IOP), and tear film thickness under the lens (central, limbal, and peripheral regions) were measured before lens insertion, immediately after insertion, 60-90 minutes post-insertion, and at one month follow-up (the average daily wearing time was 3.3±1.7 hours). Anterior segment optical coherence tomography angiography (OCTA) was used to quantitatively analyze the average blood flow density percentages within 5 mm×5 mm, 7 mm×7 mm, and 9 mm×9 mm grid areas centered on the superior, inferior, nasal, and temporal quadrants of the lens landing zone, both before lens insertion and 60-90 minutes post-insertion. Main Outcome Measures BCVA, SE, IOP, tear film thickness, and average blood flow density percentage. Results Immediately after lens insertion, BCVA improved significantly from baseline spectacle correction 0.38±0.33 logMAR to 0.08±0.12 logMAR (P<0.0001). At 60-90 minutes post-insertion, BCVA was 0.07±0.12 logMAR, which showed no significant difference from the immediate post-insertion values (P=0.2054). At one-month follow-up, BCVA remained stable at 0.07±0.09 logMAR, showing significant improvement over baseline spectacle correction (0.46±0.31 logMAR) (P<0.0001), and no significant change compared to values at 60-90 minutes post-insertion (0.06±0.09 logMAR) (P=0.9847). Tear film thickness at 60-90 minutes post-insertion was significantly reduced across all regions compared to immediately after insertion (horizontal center: 224.1±56.9 μm; vertical center: 218.6±50.7 μm; superior edge: 133.9±49.1 μm; inferior edge: 300.3±90.2 μm; nasal edge: 212.8±86.0 μm; temporal edge: 228.0±71.8 μm) (all P<0.05), and remained within ideal ranges. At one-month follow-up, tear film thickness in all regions continued to be significantly reduced compared to immediately after lens insertion (all P<0.0001). Compared to values at 60-90 minutes post-insertion, only the temporal region showed a statistically significant difference (P=0.0097), other regions showed no significant changes (all P>0.05), and all mean values remained within safe limits. OCTA showed no statistically significant differences in the average blood flow density percentages across grid areas at 60-90 minutes post-insertion (5 mm×5 mm area: 61.17%±7.50%; 7 mm×7 mm area: 57.91%±6.38%; 9 mm×9 mm area: 55.50%±5.50%) compared to before lens insertion uncorrected eyes (61.82%±6.34%, 58.48%±5.75%, 56.71%±5.51%, respectively) (all P>0.05). Conclusion Scleral lenses can significantly improve BCVA in patients with keratoconus, maintain stable visual acuity during one-month follow-up, keep tear film thickness within a safe range, and do not cause notable reductions in anterior segment blood flow density, demonstrating good short-term safety.

Key words:  Scleral lens, Keratoconus, Visual acuity, Blood flow density, Anterior segment optical coherence tomography angiography