Comparative Safety And Efficacy Of Clear (Corneal Lenticule Extraction For Advanced Refractive Surgery) And Photorefractive Keratectomy (Prk) In Myopia And Astigmatism Correction: A Retrospective Analysis Of Visual And Refractive Outcomes

To compare the early learning curve, safety, efficacy, and refractive predictability of CLEAR (Corneal Lenticule Extraction for Advanced Refractive Surgery), a KLEx (Keratorefractive Lenticule Extraction) procedure, and PRK (Photorefractive Keratectomy) for the correction of myopia and astigmatism.

This study was conducted at Centro de Estudos H. Olhos São Gonçalo, Rio de Janeiro, Brazil, between February 2025 and January 2026. All patients provided written informed consent prior to participation. All procedures adhered to the Declaration of Helsinki.

This retrospective comparative study included 129 eyes during the initial learning phase: 75 treated with CLEAR using the FEMTO LDV Z8 (Ziemer) and 54 treated with PRK using the Technolas 217z100 excimer laser (Bausch + Lomb). All procedures targeted emmetropia. Outcomes were evaluated at 1 month. Primary endpoints included uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), change in Snellen lines, spherical equivalent (SEQ) accuracy, residual refractive astigmatism, and safety and efficacy indices. The proportions of eyes within ±0.50 D and ±1.00 D of target were calculated.

Postoperative analysis at 1 month showed UDVA ≥20/20 in 73% of CLEAR eyes and 70% of PRK eyes, and UDVA ≥20/25 in 91% and 87%, respectively. UDVA was equal to or better than CDVA in 76% and 61%, respectively. Residual refractive astigmatism ≤0.50 D was observed in 56% of CLEAR eyes, and refractive accuracy within ±0.50 D in 60% versus 37% in PRK. CDVA remained stable or improved in 73% and 63%, respectively. The efficacy index was 0.96 (95% CI, 0.90–1.03) for CLEAR and 0.89 (0.83–0.96) for PRK, and the safety index was 1.01 (0.96–1.06) and 0.96 (0.91–1.01), respectively.

Both procedures demonstrated acceptable safety and good visual efficacy during the early learning curve. However, CLEAR showed faster functional recovery, refractive predictability and improved early astigmatic control compared with PRK, with a trend toward higher early efficacy.