Nominal and achieved stromal ablation depth after myopic transepithelial photorefractive keratectomy: implications for residual stromal thickness calculation.

The study revealed a central stromal ablation 16.50% greater than the nominal ablation depth. This excessive stromal removal was largely compensated for by the increase in epithelial thickness, resulting in a mean difference between the nominal ablation depth and the achieved central corneal pachymetry reduction of only 2.33%. This significant excessive central stromal ablation must be taken into consideration in the calculation of the residual stromal thickness.