Diagnostic accuracy of methods for assessing indicators of regular astigmatism

Relevance Astigmatism (Ac) is a defect of the optical system of the eye that causes uneven defocus of light. Accurate diagnosis of Ac is important for the selection of optical correction, including toric intraocular lenses [1–3]. Objective To evaluate the diagnostic accuracy of methods for indicating regular astigmatism. Material and methods The study included 83 patients (122 eyes) with regular Ac (> 1.0 D), divided into three groups by Ac type. Automatic refractometry (Tomey RC-5000) was used to determine spherical and cylindrical components, refined by subjective tests (cross-cylinder, duochrome test). Visual acuity was assessed with Tomey TCP-3000P optotypes. Deviations of the cylinder axis (5°, 10°, 15°) were modeled to analyze the impact on vision. Statistical processing included the Kolmogorov-Smirnov and Wilcoxon criteria (p < 0.05). Results The coincidence of refractometry data and subjective tests was noted in 34.4% of cases, discrepancies - in 70%. Significant differences in the cylinder size were revealed with reverse Ac (p < 0.0005). Subjective correction increased visual acuity. A deviation of the cylinder axis by 10-15° reduced vision regardless of the Ac type, and by 5° - only with direct Ac counterclockwise. Conclusion For maximum visual acuity when correcting regular Ac, the data of automatic refractometry require clarification by subjective tests [4, 5]. The results of modeling axis deviations are useful for assessing the effectiveness of toric IOL implantation. Key words: regular astigmatism; automatic refractometry; cross-cylinder; toric intraocular lens