Purpose: This study aimed to measure the changes in refraction difference value (RDV) in different parts of the retina before and after implantable collamer lenses (ICL) surgery.

Design: Prospective study.

Methods: This study included 40 eyes of 40 patients who underwent ICL implantation for myopia. RDV measurements were taken across several ranges: 0°-15°, 15°-30°, 30°-45°, and 45°-53°, and categorized into four sectors: superior (RDV-S), inferior (RDV-I), temporal (RDV-T), and nasal (RDV-N), along with total RDV (TRDV). Measurements were taken preoperatively, and at one week and one month postoperatively.

Results: TRDV, RDV beyond 15° eccentricity, and RDV-S, RDV-I, RDV-T, and RDV-N were significantly increased postoperatively. The one-week and one-month follow-up of RDVs had no significant differences. Significant differences in the increments were observed among RDV-15, RDV-15-30, RDV-30-45, and RDV-45-53 both at one-week and one-month follow-up. Similarly, there were significant differences in the increments among RDV-S, RDV-I, RDV-T, and RDV-N both at one-week and one-month follow-up. TRDV, RDV-30-45, RDV-45-53, RDV-S, RDV-T, and RDV-N showed significant differences in the variation preoperatively and postoperatively between the high (SE > -9.00 D) and ultra-high (SE ≤ -9.00 D) myopia groups.

Conclusions: Peripheral refraction showed a hyperopic defocused state that can stabilize in the early postoperative period after ICL implantation. The variation in the hyperopic defocused shift in peripheral refraction increased more in the regions farther from the central retina. The temporal regions exhibited the most changes.

Key messages: WHAT IS KNOWN : Myopia is generally believed to stabilize after adulthood, but some individuals continue to experience myopia progression, accompanied by axial length elongation. Traditional spectacle lenses correct myopia by focusing light on the fovea but may introduce peripheral hyperopic defocus, which is thought to contribute to myopia progression. ICL surgery effectively corrects high degrees of myopia and astigmatism. Previous studies have demonstrated the safety and efficacy of ICL in addressing central refractive errors, but peripheral refraction changes post-surgery have not been well-explored.

What is new: ICL surgery increased peripheral hyperopic defocus while correcting central refractive error, with significant changes in peripheral refraction observed from the preoperative to postoperative one-week and one-month.. After ICL implantation, a hyperopic shift was observed in peripheral areas, with RDV values within 15° of the central retina appearing emmetropic and increasing hyperopic defocus noted moving away from the posterior pole. Peripheral refraction stabilized approximately one week after ICL surgery, with no significant differences observed between the one-week and one-month follow-ups, indicating that stability in peripheral refraction is typically achieved within this timeframe.