Abstract
PURPOSE: This study aimed to assess the safety and efficacy of stromal lenticule addition keratoplasty (SLAK) treatment in patients with hyperopia. METHODS: This retrospective study included 43 eyes from 34 patients treated with SLAK in the Corneal Refraction Department of Jinan Mingshui Eye Hospital from October 2022 to January 2024. The cohort included 14 males (17 eyes) and 20 females (26 eyes), with a mean age of 24.33 ± 9.03 years. Statistical analysis was performed on patient data collected before surgery and at 1 week, 1 month, 3 months, and 6 months post-surgery to compare the changes across different time periods. Changes in visual acuity, SE, KM, corneal thickness, and corneal biomechanics were evaluated. A visual corneal biomechanical analyzer (Corvis ST) was used to measure the time (A1T, A2T), length (A1L, A2L) and flattening speed (A1V, A2V) of the second corneal flattening level. Additional parameters such as maximum compression time (HCT), corneal curvature radius (HCR), peak distance (PD), maximum compression depth (DA), corneal first pressure hardness parameter (SP-A1), composite radius index (IR), and biomechanical correction intraocular pressure (bIOP) were also assessed. RESULTS: Significant differences were observed in near vision (P < 0.001), uncorrected visual acuity (UCVA) (P < 0.001), and SE (P < 0.001) compared to pre-surgical data. There were also significant improvements in UCVA across different post-SLAK treatment periods (P < 0.05). Significant differences were observed in best-corrected visual acuity (BCVA) (0.43 ± 0.35) compared to UCVA (post-surgery) (F = 10.372, P < 0.001). Additionally, there were significant differences in Km, thinnest point of the cornea, and thickness of the central corneal epithelium compared to pre-surgical data (P all < 0.001). There were also significant differences in A1T, A2T, A2L, HCT, DA, and bIOP compared to pre-surgical data (P all < 0.05). There were no statistically significant differences in A1L, HCR, PD, SPA1, or IR (P all > 0.05). CONCLUSIONS: At 6-month post-SLAK follow-up, hyperopic patients achieved expected visual and refractive outcomes. The procedure increased corneal curvature and thickness, prolonged corneal deformation time, and shortened deformation distance, suggesting enhanced corneal stiffness, with most biomechanical parameters remaining stable pre- to postoperatively.