Impact of Postoperative Corneal Flattening on Visual and Refractive Outcomes in Myopic Photorefractive Keratectomy in the Early Postoperative Period

Purpose: To compare the early postoperative visual and refractive outcomes of patients who underwent myopic photorefractive keratectomy (PRK) with a postoperative mean corneal keratometry <34.00 diopters (D) versus those with a mean corneal keratometry of ⩾34.00 D. Methods: This retrospective study included 17,019 eyes that underwent myopic PRK at Care-Vision Laser Centers with 183 eyes (1.08%) classified as having a flat postoperative cornea (mean keratometry <34.00 D as defined a priori). Baseline and intraoperative characteristics were compared between the flat cornea group and a control group (mean keratometry ≥34.00 D). Postoperative outcomes, including uncorrected distance visual acuity (UDVA), spherical equivalent (SEQ), and other visual and refractive parameters, were analyzed at a mean follow-up of 147 ± 63 days (range: 3 to 12 months, similar for both groups). In a propensity-score–matched cohort (1:3) balanced on baseline and intraoperative variables (age, sex, preoperative mean keratometry, preoperative SEQ, minimum corneal thickness, and intraoperative parameters including treated spherical correction, optical zone, maximum ablation depth, and year of surgery), visual and refractive outcomes were compared between the flat cornea and control groups. Results: Patients in the flat cornea group were more likely to be male (83.1% vs 54.8%, P < .001), had greater preoperative myopia (SEQ: −10.20 ± 2.30 vs −4.90 ± 2.60 D, P < .001), and exhibited thicker minimum corneal thickness (540.7 ± 33.5 vs 530.2 ± 33.6 μm, P < .001). Intraoperatively, they received greater ablations, including a higher spherical correction (8.90 ± 1.50 vs 4.80 ± 2.20 D, P < .001) and deeper maximum ablation depth (131.7 ± 17.2 vs 82.8 ± 36.2 μm, P < .001). In a propensity-score–matched cohort (1:3) balanced on baseline and intraoperative variables, postoperative UDVA, CDVA, and refractive cylinder were similar between groups; safety and efficacy indices were also comparable. Conclusions: Postoperative flat corneas (mean keratometry <34.00 D) achieved comparable visual acuity, safety, and efficacy outcomes following myopic PRK, compared with the control group. Accordingly, the initial concerns regarding worse visual outcomes in flatter corneas may be unfounded.