High Astigmatism Correction in Myopia: A Comparative Study of Photorefractive Keratectomy and Keratorefractive Lenticule Extraction.

PURPOSE: To compare visual, refractive, and aberrometric outcomes in patients with myopia and high astigmatism corrected by photorefractive keratectomy (PRK) and Keratorefractive Lenticule Extraction (KLEX).

METHODS

This prospective, comparative study included 74 patients (74 eyes) with myopia and high astigmatism (-2.25D to -5.75D cylinder), aged 20 to 52 years, who underwent PRK and KLEX surgeries. Patients were evaluated before, and 3 and 6 months after surgery. Examinations included uncorrected and distance-corrected visual acuity, cycloplegic refraction, corneal tomography, and aberrometry.

RESULTS

Six months after surgery, the mean spherical equivalent was not significantly different between groups (P = 0.06). Graphical analysis showed that 91% of KLEX and 65% of PRK patients experienced no loss of corrected visual acuity, and 94% of eyes in both groups achieved a postoperative spherical equivalent within ±1.00 D. PRK patients showed less residual refractive astigmatism than the KLEX group (-0.58 ± 0.32D vs. -0.80 ± 0.46D, P = 0.03). Ninety-five percent of PRK and 79% of KLEX patients showed less than 1.00 D refractive astigmatism. A significant difference in the correction index was found between PRK and the KLEX group (0.99 ± 0.15 vs. 0.81 ± 0.18; P < 0.001). The efficacy index was not significantly different between groups (P = 0.12) (PRK: 1.02 ± 0.10, KLEX: 1.00 ± 0.02). Vertical coma was significantly higher in the KLEX group (P = 0.02).

CONCLUSIONS

Both PRK and KLEX are effective and predictable procedures that yield satisfactory visual outcomes for correcting myopic astigmatism. However, KLEX tends to undercorrect astigmatism in patients with high preoperative astigmatism, most likely because of the absence of a nomogram adjustment, whereas the PRK platform incorporates a built-in manufacturer correction.