Impact Of 0.5% Tropicamide-Induced Mydriasis On Corneal Wavefront Aberrations In Keratoconus: A Severity-Based And Zone-Specific Analysis

To evaluate the effects of 0.5% tropicamide-induced mydriasis on corneal wavefront aberrations in patients with keratoconus (KC) across different severity stages using the Pentacam static Scheimpflug imaging system.

Eye & ENT Hospital, Fudan University

This prospective study included 108 eyes from 108 KC patients, stratified into mild (n = 39), moderate (n = 35), and severe (n = 34) groups. Mydriasis was induced with 0.5% tropicamide. Measurement parameters, including Total Root Mean Square (Total RMS), Higher-order RMS (HO-RMS), coma, trefoil, spherical aberration, and secondary astigmatism, were evaluated at 4-mm and 6-mm zones. Data normality was assessed via the Kolmogorov-Smirnov test, with subsequent analysis using paired t-tests or Wilcoxon signed-rank tests.

Following mydriasis, patients with KC exhibited a systematic and statistically significant reduction in both Total RMS and HO-RMS at the 4-mm and 6-mm zones (p < 0.05). The impact on spherical aberration (SA) was distinctly zone-specific: measurements remained stable at the 4-mm zone (p > 0.05), whereas a significant decrease was observed at the 6-mm zone (p < 0.001). Notably, specific higher-order coefficients, including coma, trefoil, and secondary astigmatism, demonstrated remarkable robustness, maintaining statistical stability post-mydriasis across all severity levels and measurement zones (p > 0.05).

Mydriasis produced significant alterations in corneal aberration parameters in participants with KC, primarily characterized by a systematic reduction in aberration magnitudes. While clinicians should be aware of these alterations, coma, trefoil, and secondary astigmatism remain the most reliable metrics for clinical assessment due to their relative stability under mydriatic conditions.