Changes in endothelial morphology and ocular aberrations in pterygium

AIM: To compare changes in the corneal surface and endothelium, and to investigate their relationship with the horizontal length (HL), vertical length (VL), and depth of pterygium. METHODS: This study analyzed 34 eyes with unilateral primary pterygium and compared them to the 34 fellow eyes. Topographic values, wavefront aberrations, and specular microscopy findings were assessed. In addition, correlation analyses were conducted between the HLs and VLs, as well as the depth of pterygium. RESULTS: The mean age of the patients was 60.18±11.36y (38.2% females). Uncorrected visual acuity (UCVA) was lower, and corneal astigmatism was higher in the pterygium group (P=0.006 and P0.001, respectively). Simulated keratometry 1 (simK1) measurements showed significant corneal flattening in the pterygium group (P=0.038). Notably, the HL of the pterygium (r=0.646, P0.001) demonstrated a stronger correlation with corneal astigmatism than the VL (r=0.449, P=0.008). No significant correlation was observed between depth (r=-0.007, P=0.971) and corneal astigmatism. Furthermore, significant increases were noted in total higher-order aberrations (HOA; P=0.013), trefoil (P=0.002), tetrafoil (P=0.001), and high-order astigmatism (P0.001) in the pterygium group. Mean point spread function (PSF) values were also significantly impaired in the pterygium group (P=0.007). Regarding endothelial parameters, the median endothelial cell density (ECD) was 2448.50 (2176.00-2750.25 cells/mm²) in pterygium group, and 2554.00 (2252.50-2890.00 cells/mm²) in the control group (P=0.289). No correlation was found between HS or VL and specular microscopy findings. However, a negative correlation was observed between depth and hexagonality (r=-0.381, P=0.026), and between depth and central corneal thickness (CCT; r=-0.422, P=0.013). CONCLUSION: The effect of pterygium on corneal aberrations is more strongly associated with its HL than with its VL. Depth do not affect aberrations, and pterygium has no significant effect on the ECD.