Анализ изменения биомеханических свойств роговицы на приборе CORVIS ST (Oculus, Германия) у пациентов с миопией и миопическим астигматизмом после операции ФРК

Abstract

Purpose. To analyze changes in corneal biomechanical properties after refractive surgery of photorefractive keratectomy (PRK) in patients with myopia and myopic astigmatism. Material and methods. The study included 10 patients (20 eyes) aged 23 to 51 years, planned for keratorefractive surgery for myopia and myopic astigmatism. Spheroequivalent of myopic refraction was -2.5 to -9.25 diopters, corneal astigmatism: -0.5 to 4.25 diopters. Patients underwent keratotopography using Pentacam scanning projection topograph (Oculus, Germany) and study of cornea biomechanical properties using Corvis ST non-contact tonometer (Oculus, Germany) at baseline and 1 month after surgery using the PRK technique. Results. Initially, in 3 patients (30%), keratotopogram showed elevation along posterior corneal surface (up to +26) and increase in corneal curvature in lower sections. Tomographic Biomechanical Index in all 10 patients ranged from 0.01 to 0.46, with 3 of them exceeding 0.3. Central Corneal Thickness in all patients averaged 514 ± 31 µm, of which 7 patients (70%) had 500 µm or less. Month after surgery only two indicators revealed statistically significant difference: Inverse Concave Radius (on average 5.95 ± 0.79 mm before surgery and 7.02 ± 0.70 mm after) and the Central Corneal Thickness (514 ± 31 µm before surgery and 410 ± 41 µm after). Conclusion. When selecting patients for keratorefractive surgery, it is imperative to take into account the initial corneal biomechanical properties to select the optimal technique in each specific case. Key words: corneal biomechanical properties, photorefractive keratectomy, myopia, myopic astigmatism.