Screening for keratoconus early signs in planning keratorefractive surgery

Clinical relevance. Keratoconus (KC) without clinical manifestations (subclinical stage) occurs in patients with ametropia periodically. Before refractive surgery, in time detection of early signs of this pathology is important as KC is a contraindication to its application.Purpose: to analyze and compare informative value of the Pentacam HR projection-based tomograph, the TOMEY TMS-4 reflecting-based corneal topographer and the CASIA-2 optical coherent tomograph to identify early signs of KC before refractive laser surgery.Materials and methods. A prospective study of cornea morphometric parameters in 81 patients (162 eyes) who applied to the Cheboksary branch of the Intersectoral Scientific and Technical Complex “Eye Microsurgery” was performed in order to resolve the issue of refractive surgery possibility with various types of ametropia during the second half of 2020 year. In addition to the generally accepted ones, examinations were carried out using the above-mentioned devices. Age of the patients ranged from 18 to 38 years old (on average 25 ± 5). The sample consisted of 33 (40.81%) men and 48 (59.19%) women.Results. According to the TOMEY TMS-4 reflecting-based corneal topographer, suspicion of KC was detected in 6 patients (11 eyes) that amounted to 6.79% of all examined patients. The Pentacam HR projection-based tomograph revealed suspicion of KC in 9 patients (18 eyes or 11.11% of all examined patients). While using the CASIA-2 optical coherent tomograph, suspicion of KC was detected by ESI (Ectasia Screening Index) Anterior in 6 patients (11 eyes), and by ESI Posterior in 7 patients (14 eyes) that amounted to 6.79 and 8.64% of all examined patients respectively.Conclusion. The data obtained during the study showed the greatest informativity and efficiency of the Pentacam tomograph in screening for early signs of KC.