High-altitude effect on corneal endothelial cells and prognosis in patients with cataract surgeries: a propensity score matched analysis

Abstract

Aim: To compare analysis of the impact of high altitude on corneal endothelial cells, and the prognosis in patients with cataract surgeries.

Methods: Totally 265 plateau patients with cataract surgeries performed between January 2019 and July 2022 (average altitude=3000 m), and 524 plain patients with cataract surgeries performed between January 2020 and July 2022 were included. The propensity score matching (PSM) method was applied to match the basic information of patients in both regions on a 1:1 basis. Corneal endothelial cell density (ECD), coefficient of variation (CV), hexagonal cell ratio (HEX), duration of surgery, and pre- and postoperative visual acuity (VA) were compared retrospectively, and correlation tests were done.

Results: Totally 223 pairs have been matched successfully. The HEX in the plateau group was higher than that in the plain group (61.95%±6.191% vs 44.91%±6.829%, P<0.001). For ECD and CV, no significant differences were observed between both groups (P>0.1). The pre- and postoperative VA of patients with cataract surgeries in the plateau group were lower (1.40±0.610 vs 0.71±0.514, P<0.001 & 0.68±0.479 vs 0.18±0.259, P<0.001), and the duration of surgery was longer than those in the plain group (27.06±14.900 min vs 16.03±8.033 min, P<0.001). No significant associations were found between the post-operative VA and the corneal endothelial parameters (P>0.05), while the post-operative VA was significantly related to the pre-operative VA and the duration of surgery (P<0.05).

Conclusion: The relative hypoxic environment of the plateau does not promote the apoptosis of corneal endothelial cells, but may lead to the compensatory increase of their functions. In plateau patients, no significant associations are found between the poor VA and the corneal endothelial functions early after cataract surgeries.

Keywords: cataract surgery; corneal endothelial cells; hypoxia; plateau; propensity score matching.

Figure 1. Comparison of corneal endothelium parameters in the plateau and plain groups after PSM

^aP<0.05, ^bP<0.01. ECD: Corneal endothelial cell density; ACS: Average cell size; CV: Coefficient of variation; HEX: Hexagonal cell ratio; MAX: Maximum cell size; MIN: Minimum cell size.

Figure 2. Heatmap of correlations between corneal endothelium parameters, operation duration, and BCVA

^aP<0.05, ^bP<0.01. ECD: Corneal endothelial cell density; ACS: Average cell size; CV: Coefficient of variation; HEX: Hexagonal cell ratio; BCVA: Best corrected visual acuity.