Progressive sensory nerve damage in the cornea may represent an underappreciated pathway of age-related eye dysfunction, particularly in individuals with genetic vulnerabilities. This finding challenges the assumption that corneal sensitivity remains stable throughout life and suggests new targets for preserving vision quality in aging adults.
Investigators studying 14 patients with congenital aniridia—a rare genetic condition affecting iris development—discovered that corneal sensitivity to mechanical pressure drops significantly with age, falling from normal ranges to just 2.2 on a 10-point scale in adults versus 3.9 in healthy controls. Cold sensitivity similarly declined to 3.8 compared to 5.5 in controls. Most striking was the near-complete loss of reflex tear production capacity, with patients showing only 1.9mm of tear reserve compared to 12.7mm in healthy individuals. The deterioration proved most severe in patients carrying complete loss-of-function PAX6 mutations and those with advanced corneal scarring.
This research illuminates how genetic factors governing eye development may create vulnerabilities that compound normal aging processes. The PAX6 gene regulates not only iris formation but also corneal nerve development and maintenance. While aniridia affects fewer than 1 in 50,000 people, the mechanistic insights may apply more broadly to age-related dry eye syndrome, which affects millions worldwide. The dramatic reduction in tear reflex capacity suggests that corneal nerve health deserves greater attention in routine eye examinations, particularly for older adults experiencing dry eye symptoms. However, the small sample size and focus on a rare genetic condition limit immediate clinical applications until larger studies confirm these patterns in typical aging populations.
