Age Impairs Corneal Sensitivity and Reflex Tearing in Congenital Aniridia.
Academic Article
Overview
abstract
PURPOSE: To characterize, for the first time, corneal sensory nerve functionality in congenital aniridia by assessing mechanical and cold corneal sensitivity, reflex tearing, and basal blinking and tearing. METHODS: A cohort of fourteen pediatric and adult patients with PAX6-related aniridia was enrolled in the study. Mechanical sensitivity (noncontact gas esthesiometer) and cold sensitivity (4°C drops) were quantified using a 0 to 10 verbal numerical scale (VNS). Spontaneous blinking, basal, and CO2-induced reflex tearing were also measured. Data were stratified by age, aniridia-associated keratopathy (AAK), and PAX6 mutation type-reduced expression or loss-of-function (LOF) genetic variants-and compared with healthy controls (n = 9). RESULTS: Mechanical sensitivity to high-intensity stimuli was reduced in patients with aniridia, particularly in adults (2.2 ± 0.3 VNS, P = 0.02), those with severe AAK (2.4 ± 0.4 VNS, P = 0.09), and patients with LOF mutations (2.4 ± 0.2 VNS, P = 0.05) compared with controls (3.9 ± 0.5 VNS). Cold sensitivity was also reduced in adult patients (5.5 ± 0.5 vs. 3.8 ± 0.6 VNS, P = 0.05) and severe AAK (3.2 ± 0.8 VNS, P = 0.01). Reflex tearing values exhibited variability but trended lower in patients than controls, and tearing reserve (reflex minus basal tearing) was significantly reduced (12.7 ± 3.8 vs. 1.9 ± 1.9 mm, P = 0.02). Basal blinking and tearing were not significantly different. CONCLUSIONS: These findings suggest impaired mechano-nociceptors, polymodal nociceptors, and cold thermoreceptors function in congenital aniridia, with severity increasing with age and AAK grade. LOF mutation results show a trend with greater deficits than reduced expression variants, highlighting a critical role of PAX6 in corneal sensory integrity.
