Analysis of topographic corneal parameters in a large cohort of corneal refractive surgery candidates

Analysis of different corneal parameters in patients seeking corneal refractive surgery.

Patients examined by Oculus Pentacam^® HR from Oculus, Inc. at Roaa Laser in situ keratomileusis center, Minia, Egypt, during the period from July 1, 2023, to the end of December 2023 from both sexes between 18 and 45 years asking for corneal refractive surgery were reviewed. The following parameters were obtained and analyzed: K1 (Flat K)-K2 (Steep K)-K max-Pachymetry at corneal apex - Pachymetry at thinnest location - Distance between apex and thinnest location - Corneal back elevation - Topography shape - Keratoconus (If present). Patients with previous corneal surgery, intraocular surgery, or corneal opacity were excluded from the study.

The study included 5059 eyes of 2694 subjects; the mean age was 27.46 ± 7.04 (18-45) years, and most of them were of female gender, representing 1886 subjects (70.007%). The mean spherical equivalent was - 2.94 ± 3.68 diopters. The most common topographic shape was a symmetric bow tie in 2474 eyes (48.9%). Abnormal back elevation was reported in 19.4% of studied eyes and keratoconus in 4.1% of the studied eyes.

Examination of refractive surgery candidates revealed that high myopia is frequent, the most frequent topographic shape is the symmetric bowtie, and keratoconus is infrequent, but abnormal back elevation had a higher percentage. Therefore, routine corneal examination by pentacam is recommended for these patients regardless of whether they are seeking refractive surgery or not. Our findings emphasize the importance of conservative pachymetry thresholds (≥500 µ) in regions with higher keratoconus risk. Future research should focus on longitudinal tracking of refractive surgery candidates to better understand the impact of subclinical ectasia markers on long-term outcomes.