Two single descriptors of endothelial polymegethism and pleomorphism

Abstract

Purpose: To compute two new quantitative parameters that directly reflect the level of polymegethism and pleomorphism using data provided by a non-contact specular microscope.

Methods: We examined right eyes of 306 voluntaries (102 males, 204 females) whose ages ranged from 6 to 82 years (mean +/- SD, 44 +/- 22 years). Endothelial cell density (ECD), average cell size (ACS), standard error of cells surface (SEM), coefficient of variation in cell size (CV) and hexagonality index (HI) were obtained. In addition, two new indices of polymegethism (POLi) and pleomorphism (PLEi) were derived using weighted linear combinations of data obtained from instrument classification of endothelial cells based on the individual counts of cells by size and number of sides respectively, as provided by the instrument. Values of POLi and PLEi were compared between a group of diabetic patients and a group of age-matched controls.

Results: Average values of POLi and PLEi were 10.47 +/- 3.94 and 8.36 +/- 1.21 respectively. POLi and PLEi display high correlation with SEM (r = 0.911, r = 0.664), ECD (r = -0.997, r = -0.585), ACS (r = 0.997, r = 0.441), ACS (SD) (r = 0.883, r = 0.682), CV (r = 0.301, r = 0.712) and HI (r = -0.437, r = -0.991); all these correlations were highly significant (p < 0.001). POLi and PLEi also showed significant positive correlations with age (r = 0.765, p < 0.001 and r = 0.428, p < 0.001 respectively). POLi was significantly higher in a group of diabetic patients when compared with another group of age-matched controls (p = 0.001).

Conclusions: Two single quantitative parameters of endothelial polymegethism and pleomorphism (POLi and PLEi respectively) have been derived from the data obtained with a commercial non-contact specular microscope. These parameters have been demonstrated to identify differences between the corneal endothelium of diabetic and non-diabetic patients.