Evaluating Corneal Optical Density and Subbasal Nerve Fiber Metrics in Myopic Patients

To assess corneal metrics in myopic patients and investigate the relationship between myopia severity and corneal characteristics.

Consecutive myopic patients undergoing preoperative evaluations for refractive surgery were enrolled. Comprehensive clinical data, including age, gender, axial length (AL), and spherical equivalent refraction (SER) were collected. All enrolled patients completed the ocular surface disease index (OSDI) questionnaire. Myopia severity was categorized based on SER and AL. Detailed corneal optical density (COD) was measured using Pentacam HR imaging. In vivo confocal microscopy (IVCM) was performed to measure central corneal sub-basal nerve plexus (SNP) and dendritiform cell (DC) density. Correlations among metrics were analyzed, and differences across various levels of myopia severity were assessed.

The study included 157 participants (308 eyes), predominantly female (118 females, 39 males), with a mean age of 28.0 ± 6.64 years (range 17-52). The mean SER was -6.85 ± 3.0 D (range -18.00 to -0.50 D), and the mean AL was 26.32 ± 1.4 mm (range 22.92-30.42 mm). OSDI showed a positive correlation with corneal nerve branch density (CNBD). Age correlated significantly with COD in the 6-10 mm zones of the anterior, middle, posterior and total layers (all P < 0.05), as well as in the 10-12 mm zones of the middle (P = 0.020) and total layers (P = 0.023), but showed no impact on SNP metrics. DC density exhibited a correlation with SNP metrics. Central COD (0-6 mm zone) increased with myopia severity, showing a negative correlation with SER and positive correlations with AL, with significant changes observed in the middle, posterior, and total corneal layers. No significant effects of myopia severity were observed on SNP metrics.

This study highlights complex relationships between corneal metrics in myopic patients. COD values in the central 0-6 mm zone increased with higher myopia severity, while no significant relationships were found with SNP metrics.