Changes in corneal dynamics and effective optical zone after transepithelial photorefractive keratectomy for myopia

OBJECTIVES: To analyze the changes in the effective optical zones (EOZ) using topographic techniques on the tangential curvature difference map at postoperative 1-year following transepithelial photorefractive keratectomy (T-PRK) and to identify parameters linked to the EOZ alterations.
METHODS: The study comprised 55 eyes of 55 myopic patients who underwent T-PRK. EOZs were measured using the tangential curvature difference map of the Scheimpflug tomography system. Correlations between the EOZ alterations and relevant parameters were assessed.
RESULTS: The EOZ was significantly lower than the programmed optical zone (p<0.001). The decrease in the EOZ was significantly relevant to the decrease in mean keratometry (p=0.01, B / 95%CI: 0.139 / 0.033 and 0.244, standardized Beta: 0.346) and the increase in maximum keratometry (p=0.003, B / 95%CI: 0.072 / 0.026 and 0.118, standardized Beta: 0.406).
DISCUSSION AND CONCLUSION: The EOZ decreased in the first year after T-PRK in eyes with myopia. The decrease in the EOZ was correlated positively with the decrease in mean and maximum keratometry. T-PRK may be an effective and safe surgery for the correction of mild to moderate myopia.