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Iris color and age-related changes in lens optical density
B R Hammond1, J E Nanez, C Fair
1Department of Psychology, University of Georgia, Athens 30602-3013, USA.
Summary
Dark iris color is linked to higher lens optical density (OD) in individuals without cataracts, particularly in older adults. This suggests iris pigmentation may influence age-related lens changes.
Area of Science:
- Ophthalmology
- Vision Science
- Human Physiology
Background:
- Epidemiological studies link dark iris color to increased cataract risk.
- Limited data exists on the relationship between iris color and pre-cataract lens changes.
Purpose of the Study:
- To investigate the association between iris color and lens optical density (OD) in individuals without clinical cataracts.
- To determine if iris pigmentation affects pre-cataractous lens properties.
Main Methods:
- Compared lens OD in 90 light-eyed (blue/green) and 87 dark-eyed (hazel/brown/black) subjects.
- Lens OD was measured psychophysically using scotopic thresholds at 410 nm and 550 nm.
- Controlled for smoking, diet, and age, as groups were similar in these aspects.
Main Results:
- Lens OD was significantly higher in the dark-eyed group compared to the light-eyed group (p < 0.024).
- This difference was primarily observed in older subjects (>45 years, p < 0.005), with no significant difference in younger subjects (20-45 years).
Conclusions:
- Iris pigmentation appears to be directly associated with age-related increases in lens optical density.
- This finding suggests a potential direct biological link between iris melanin and lens aging processes.