A comparative study of Pentacam indices in various types and severities of refractive error in candidates for photorefractive keratectomy (PRK) surgery

This study aimed to specify Pentacam indices in patients who suffered from different types of refractive error and underwent photorefractive keratectomy (PRK) surgery. It is a descriptive cross-sectional study carried out on 1125 patients (2215 eye samples) who underwent PRK surgery in the Noor Surgical Center of Ardabil, Iran, over a 5 year period (2014–2018). A particular checklist was provided to patients, which consisted of demographic data, pachymetry test, keratometry, refractive error, corneal-thickness indices, and corneal surface area indices. The data were analysed using the statistical analysis package of IBM(®) V25. The mean age of the participants in this study was 28.48±6.82 years, and the ratio of women to men was 66.4%. It was observed that the differences between angle, volume, the depth of the anterior chamber, IVA, and ISV were significant (P=0.00) when compared to each other in all types of refractive errors. High myopes had significantly higher K(max) front than low myopes (P=0.00). In astigmatism patients, the K(max) in front of the cornea in extreme type was significantly higher than in moderate (P=0.00) and high (P=0.01) types. High myopes had significantly lower R(min) than mild myopes (P=0.02), and extreme astigmatism had significantly lower R(min) than high (P=0.014) and moderate types (P=0.013). The data from this study revealed that in patients undergoing PRK surgery, some Pentacam indices could be related to some types of refractive error, and in some of these indices, there are statistically significant differences between different severities of refractive errors. Therefore, their preoperative evaluation is very important.