The role of the epithelium in intraocular lens and corneal power calculation

Purpose: To investigate the influence of the corneal epithelium on corneal power, particularly in special cases such as post-refractive surgery and keratoconus. Methods: A retrospective observational study. Measurement data were obtained from a high-resolution anterior segment analyser (CSO MS-39). Corneal curvature and power data, as well as surface height data, were organised in a cylindrical coordinate system. Calculations considered one, two and three refractive surfaces, examining the role of epithelial thickness and stromal curvature. Results: The effect of the epithelium on corneal power was minimal (<0.1 D) in normal corneas, but it was considerable in keratoconus and post-refractive surgery cases, with differences up to 0.9 D. The effect decreased for larger measurement zones. Conclusion: Incorporating epithelial thickness and stromal curvature into corneal power calculations is a crucial next step in accurate corneal power and intraocular lens calculation in eyes with previous refractive surgery or keratoconus. This study highlights the need for advanced diagnostic and calculation methods in complex cases.