Long-Term Follow-Up In A Clinical Study Of Transepithelial Photorefractive Keratectomy Versus Conventional Photorefractive Keratectomy

Transepithelial photorefractive keratectomy (tPRK) is an updated technique for the correction of ametropia based on the well-established surgical procedure of conventional PRK. Unlike conventional PRK, which involves a two-step process of physical removal of the corneal epithelium prior to excimer laser treatment of the stroma, tPRK uses the excimer laser to complete both activities in a single step.  This study reports 3-year follow up of these two surface ablation procedures to show their long term viability as proven refractive procedures.

This study was conducted at the Asian Eye Institute, Makati City, Philippines.

This was a prospective, randomized, controlled, contralateral, masked, single-surgeon study of adult subjects with myopia with a manifest residual spherical equivalent (MRSE) of ≤–1.5D or hyperopia with an MRSE of ≥+1.5D.  Thirty-five patients undergoing refractive correction for ametropia received tPRK in one eye and conventional PRK in the contralateral eye. Outcomes assessed included manifest refraction spherical equivalent (MRSE), monocular uncorrected and corrected distance visual acuity (UDVA and CDVA), refractive predictability, adverse events, and patient-reported visual outcomes. 

At 36 months, both groups demonstrated sustained visual and refractive stability. Mean (SD) photopic UDVA was −0.02 (± 0.09) logMAR for tPRK and 0.03 (± 0.14) logMAR for PRK; mean photopic CDVA was −0.06 (± 0.06) logMAR and −0.05 (± 0.06) logMAR, respectively. Under mesopic conditions, mean UDVA was 0.01 (± 0.12) logMAR for tPRK and 0.03 (± 0.15) logMAR for PRK; mean CDVA was −0.03 (± 0.10) logMAR and −0.05 (± 0.05) logMAR, respectively. Mean MRSE was 0.03D (±0.37) and –0.14D (±0.39) at 6 months for tPRK and PRK, respectively and remained close to plano out to 36 months (−0.24D [± 0.31] and −0.31D [± 0.38], respectively). No eyes experienced clinically significant CDVA loss and there were no clinically significant adverse events.

Overall, tPRK demonstrated visual and refractive outcomes equivalent to conventional PRK through 36 months, supporting its long-term effectiveness as a surface ablation technique with procedural advantages in terms of speed and efficiency.