Coefficient of biomechanical stress as a criterion for evaluating the effectiveness of intraocular pressure compensation

Relevance Intraocular pressure (IOP) is the only controlled factor in glaucoma. Glaucoma treatment begins with correct assessment and normalization of IOP [1–3]. The accuracy of its measurement depends, among other things, on the characteristics of the fibrous membranes of the eye. Currently, a method of bidirectional pneumoapplanation of the cornea is used to study them using a special analyzer of viscoelastic properties - Ocular Response Analyzer (ORA). Mathematical processing of data obtained with the help of the device made it possible to create a biomechanical stress coefficient (Kbs), which reflects changes in the fibrous membrane of the eye under the influence of intraocular pressure and can be used to control ophthalmotonus [4]. Objective To establish the limits of the Kbs norm and to evaluate how accurately this indicator reflects the degree of compensation of intraocular pressure. Material and methods The study was divided into two parts. The first part retrospectively evaluated a control group of 400 people (800 eyes) without serious ophthalmopathology. The second part of the work examined a group of 673 patients (1346 eyes) with the first established diagnosis of uncompensated primary open-angle glaucoma. This part of the study was aimed at studying the specificity of Kbs. Results During the study, it was determined that the threshold value of Kbs is set at 1. In the range of 1–1.09, it is necessary to take into account the associated risks of glaucoma development to determine the degree of compensation of intraocular pressure. Kbs equal to 1.1 and above indicates high ophthalmotonus and predicts a significant risk of glaucoma occurrence or progression. For patients with glaucoma and uncontrolled IOP, the Kbs indicator has a specificity of 81.5%, and the extended specificity (taking into account the borderline values) reaches 98%. When the Kbs value exceeds 1.1, its specificity becomes absolute – 100% [5]. Conclusion Clinical and statistical analysis showed that the coefficient of biomechanical stress of the fibrous membrane of the eye is an effective tool for the diagnosis and treatment of glaucoma. It has high sensitivity and specificity. Keywords: intraocular pressure; glaucoma; corneal-compensated intraocular pressure; coefficient of biomechanical stress; fibrous membrane of the eye