Abstract
PURPOSE: To investigate regional variations in guttae distribution in Fuchs endothelial corneal dystrophy (FECD) and evaluate its relationship with anatomical ultraviolet (UV) protection by the eyelid. DESIGN: A prospective observational study. PARTICIPANTS: This study involved 19 eyes of 19 patients with FECD between April 2022 and June 2024 at Kyoto Prefectural University of Medicine. METHODS: Using slit-scanning wide-field contact specular microscopy, we analyzed guttae distribution in 5 corneal regions (central, superior, temporal, nasal, and inferior). Marginal reflex distance (MRD) was measured to assess the eyelid position. Proportion of guttae was quantified using image analysis. MAIN OUTCOME MEASURES: Regional differences in guttae distribution and correlation with MRD measurements. RESULTS: The superior region demonstrated a significantly lower proportion of guttae (29.4%) compared with central (69.0%), temporal (57.4%), and nasal areas (57.5%) (all P < 0.05). The difference between superior and inferior areas (45.6%) was not significant (P = 0.08). Margin reflex distance measurements showed no significant correlation with superior guttae distribution (P = 0.40). CONCLUSIONS: Our study reveals a distinct regional variation in FECD progression, with relative sparing of the superior cornea suggesting potential UV-protective mechanisms. Although not directly correlated with eyelid position, these findings indicate that environmental factors may influence disease progression. This insight suggests the potential benefit of UV protection as a preventive strategy, particularly in early-stage FECD patients. FINANCIAL DISCLOSURES: Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.