Analysis of lens parameters and position using optical coherence tomography

Relevance Anterior segment optical coherence tomography (ASOCT) is a modern non-contact method of examination that provides detailed three-dimensional images of the lens. AS-OCT provides a more accurate and objective assessment of its structure and morphology than other methods, allowing for the detection of pathological changes and the calculation of quantitative characteristics (for example, density) that are important for assessing the degree of opacity [1–3]. The introduction of anterior segment optical coherence tomography (AS-OCT) CASIA2 (Tomey Corporation, Japan) into clinical practice significantly expands the possibilities of structural and functional diagnostics of the anterior segment of the eye. The CASIA2 system measures various parameters of the lens (thickness, radius of curvature of the anterior and posterior surfaces, deviation from the central axis, tilt angle) and the cornea (central thickness, depth of the anterior chamber, radius of curvature of the anterior and posterior surfaces of the cornea), and also has an increased scanning depth (up to 13 mm). Measuring the curvature of the anterior and posterior surfaces of the cornea, as well as determining the optical power of the lens, significantly improves the accuracy of component analysis of the eye's refraction, especially in myopia. In 2022, studies using the fundamentally new SS AC-OCT CASIA2 technology showed that high myopia is associated with a statistically significant decrease in the thickness, tilt angle and curvature of the anterior surface of the lens. Accommodation additionally reduced the curvature of the anterior surface and the depth of the anterior chamber; a decrease in the curvature of the posterior surface was observed only in high myopia. In phacosurgery with high ametropia or insufficient strength of the lens capsular apparatus, the method of choice is the implantation of posterior chamber intraocular lenses (IOLs) with fixation in the ciliary sulcus. In such cases, to select the IOL parameters, it is necessary to measure the distance from sulcus to sulcus, which is carried out using ultrasound biomicroscopy, but an alternative may be the indicator - the distance between the angles of the anterior chamber, for the determination of which one can use OCT of the anterior segment of the eye [4, 5]. Conclusion The results of the studies indicate the prospects for the introduction of optical coherence tomography into clinical practice using CASIA2 technology. In addition to analyzing the parameters and position of the lens, using OCT of the anterior segment of the eye, it is possible to study the structures that affect the hydrodynamics of the eye, assess the extraocular muscles. Key words: optical coherence tomography; lens