Morphological characteristics of animal’s cornea after ultraviolet corneal crosslinking with a hypoosmolarsolution of riboflavin

Purpose. To give a morphological assessment of hypoosmoticriboflavin solution application for ultraviolet corneal crosslinking(CXL). Material and methods. Experiments were conducted on 12rats (24 eyes), standard (epi-off) CXL was performed in the 3 mW/cm2mode for 10 minutes. All animals were divided into 2 groups: in the1st, an isoosmotic solution of 0.1% riboflavin was used, in the 2nd —a hypoosmotic solution of 0.1% riboflavin. Histological studies of theeyes were performed according to the generally accepted method withhematoxylin-eosin staining and according Van Gieson method. Lightmicroscopy of histopreparations was performed. Results. Morphologicalpicture of the cornea in the early postoperative period after CXL withisoosmotic riboflavin solution was characterized by a decrease in therelative density of keratocytes, appearance of areas of fibrous collagenstructure indicating the development of stromal edema, followed (on day7, 30) by a weakening of signs of stroma swelling. Endothelium structurehad no changes. A comparative analysis of histopreparations of the twogroups showed that the severity of stroma collagen edema after CXLwith a hypoosmotic solution was generally comparable to the group ofanimals where an isoosmotic solution was used. Development of stromaledema and an increase in corneal thickness occurs intraoperatively,provided that the required frequency of instillations is observed duringthe CXL procedure. Conclusion. Stroma hydration and corneal thicknessincrease induced by hypoosmotic riboflavin solution in the CXL processoccur intraoperatively and are reversible. Morphological changes of thecornea after CXL with hypoosmotic riboflavin are generally identical tothose of animals after CXL with a standard isoosmotic solution. CXL withhypoosmotic riboflavin solution did not cause any pathological changesin the corneal endothelium. Key words: ultraviolet corneal crosslinking, hypoosmotic riboflavinsolution, thin cornea