Marfan Syndrome: Structural and Functional Characteristics of the Eye. Anatomical Changes of the Lens

Relevance The most common ophthalmological clinical manifestations of Marfan syndrome are lens luxation (46.16%) and cataract (26.92%), which, when progressing, are complicated by secondary glaucoma, lens myopia, and strabismus. The information provided requires a comprehensive analysis of changes in the structure of the lens, which should take into account not only its position, but also the state of the supporting and accommodative (zonule of Zinn and ciliary body) components [1–5]. Traditional optical methods for examining the anterior segment of the eye are limited due to the opacity of the iris. To visualize the structures located behind the iris, radiation methods such as ultrasound biomicroscopy (UBM) are used. Objective To assess the state of the anatomical complex of the lens in Marfan syndrome using UBM. Material and methods The study is based on clinical material previously used to analyze changes in the fibrous membrane of the eye in SM. At the first stage, two groups were formed: the main group (19 patients with SM, 38 eyes) and the control group (24 patients with myopia, 48 eyes), standardized by age and the size of the anterior-posterior axis (APA). At the second stage, patients with SM were divided into subgroups depending on the presence or absence of biomicroscopic signs of ectopia lentis (22 and 16 eyes, respectively). For UBM, an ultrasonic linear sensor with a frequency of 50 MHz was used (Aviso device; Quantel Medical, France). Using UBM, the following biometric parameters were determined: lens thickness and diameter, lens thickness to AL ratio, iris-lens contact angle and length, posterior chamber depth, length of Zinn ligament fibers, ciliary body thickness, and sclerociliary angle. Results Patients with Marfan syndrome exhibit changes in the anatomical complex of the lens: increased thickness and decreased diameter of the lens, elongation of the Zinn ligament, and decreased ciliary body thickness. Lens displacement detected using optical biomicroscopy can be considered as a consequence of significant changes in the anatomical complex. Conclusion UBM is an effective method for visualizing all components of the anatomical complex of the lens, which is important for both diagnostics and monitoring changes in Marfan syndrome. However, the need to include this method in the algorithm for diagnosing ocular manifestations for verifying SM remains controversial. Obstacles may be associated with high equipment costs and the lack of generally accepted standards for UBM indices for the anatomical complex of the lens. Keywords: Marfan syndrome; ultrasound biomicroscopy; anatomical complex of the lens