Rod and Cone Dark Adaptation in Congenital Aniridia and Its Association With Retinal Structure

Area of Science:

• Ophthalmology
• Genetics
• Retinal Physiology

Background:

• PAX6 gene mutations are a primary cause of aniridia, a congenital eye disorder.
• Aniridia often involves significant ocular abnormalities, impacting visual function.
• Understanding the full spectrum of visual dysfunction in aniridia is crucial for patient management.

Purpose of the Study:

• To investigate the relationship between dark-adapted rod and cone sensitivity and retinal structure in individuals with PAX6-related aniridia.
• To compare visual function and retinal anatomy in patients with aniridia versus healthy controls.

Main Methods:

• Dark-adaptation curves were measured using red and green light stimuli in 27 aniridia patients and 38 controls.
• Cone and rod thresholds were determined using a two-stage exponential model.
• Optical coherence tomography (OCT) assessed macular retinal layer thickness; clinical examination quantified aniridia-associated keratopathy (AAK) and lens opacities.

Main Results:

• Rod-cone break time was similar between groups, but dark-adapted cone and rod thresholds were elevated in aniridia.
• Foveal outer retinal layer thickness correlated with final cone and rod thresholds in aniridia patients.
• Outer retinal thickness and age were key predictors of visual thresholds in aniridia with mild to moderate AAK.

Conclusions:

• Both rod and cone visual functions are impaired in PAX6-related aniridia.
• Retinal anatomical and physiological changes in aniridia extend beyond the central macula.
• These findings highlight the widespread impact of aniridia on retinal function and structure.