Screening Thresholds for the Corneal Tomography in a Myopic Pakistani Population.

OBJECTIVE: To evaluate key corneal tomography parameters for screening refractive surgery patients in Pakistani population.

STUDY DESIGN: Cross-sectional, observation study.

PLACE AND DURATION OF STUDY: Armed Forces Institute of Ophthalmology AFIO, National University of Medical Sciences, Rawalpindi, Pakistan, from August 2013 to December 2016.

METHODOLOGY: Myopic patients were evaluated by two separate observers on Allegro OculyzerII (Wavelight) for normal ocular examination. A total of 20 tomographic parameters, used for pre-refractive surgical evaluation, were included. Normality of data was evaluated using Kolmogorov-Smirnov test. Results for outliers were displayed as 2.5%, 5%, 95% and 97.5% percentiles.

RESULTS: The sample of 451 patients (895 eyes), comprised of 61% (n=277) females and 39% (n=174) males (39%). The mean age was 26 +6.4 years (range of 18-62 years, M=F). Normal mean anterior segment values included; flat simulated keratometry (K1) 42.9 ±1.44 diopters (D), steep K2 43.9 ±1.52 D, K mean 43.4 ±1.43 D, K maximum 44.6 ±1.56 D, astigmatism -0.96 ±0.97 D, anterior chamber depth (ACD) 3.19 ±0.28 mm, front elevation at the thinnest point 4.11 ±2.44 um, and that at the back was 7.56 ±4.52 um progression index (PI) maximum 1.14 ±0.17, Ambrosio relational thickness maximum (ART max) 487.5 ±89.0 and pachymetry at thinnest point 542.2 ± 31.1 um.

CONCLUSION: The study demonstrates key corneal tomography parameters, which can be useful for screening refractive surgery patients in Pakistani population.