Assessment of the safety of wearing scleral rigid gas permeable lenses in keratoconus according to endothelial microscopy

Relevance It is known that one of the markers of normal functioning of the cornea is the state of its endothelial layer [1, 2]. Currently, the most accessible and safe method for assessing the state of the endothelium is endothelial microscopy. The issue of a detailed study of the state of the endothelial layer in keratoconus (KK) against the background of long-term wearing of scleral rigid gas-permeable lenses (SGPCL) is poorly studied today [3, 4]. Objective To study the state of the endothelial layer of the cornea in keratoconus against the background of long-term wearing of scleral rigid gas-permeable lenses. Material and methods Fifty patients (100 eyes) with KK of various stages according to Amsler (stage I - 28 eyes; stage II - 25 eyes; stage III - 29 eyes; stage IV - 8 eyes) were examined, for whom optical correction of SGPCL was selected. All patients underwent standard ophthalmological examination. The dynamics of the corneal endothelial layer condition was performed using endothelial microscopy SP-3000P (Topсon, Japan) before and after one year of wearing the SGCL. The following main parameters were determined: endothelial cell density (ECD, cells/mm2), average endothelial cell area (ACE, μm2), coefficient of variation (CV, %) and percentage of hexagonal cells (HEX, %). Results The average ECD before wearing lenses was 2551 ± 499 cells/mm2. ACE values ​​were 386.12 ± 81.8 cells/mm2. The coefficient of variation and percentage of hexagonal cells were 42.66 ± 13.2 and 52.87 ± 9.7%, respectively. After one year of wearing the SGCL, all indicators had statistically insignificant changes. The average value of the PEC decreased by 1.4% and amounted to 2517 ± 523 cells/mm2 (p = 0.218). The SPEC increased by 1.3% and amounted to 391.34 ± 96.7 cells/mm2 (p = 0.578). The coefficient of variation increased by 3.5% and was equal to 44.21 ± 13.6% (p = 0.086), and the percentage of hexagonal cells decreased by 2% and amounted to 51.84 ± 10.6% (p = 0.477). Conclusion Thus, the obtained data allow us to conclude that the quantitative and qualitative indicators of the state of the endothelial layer of the cornea before and after a year of wearing the SJGCL in patients with CC do not differ significantly from each other, which indicates the safety of using lenses of this type in keratectasia. Key words: keratoconus; scleral rigid gas-permeable lenses; endothelial microscopy