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Iris color and intraocular pressure: the Blue Mountains Eye Study
Robert Mitchell1, Elena Rochtchina, Anne Lee
1Christchurch School of Medicine, University of Otago, Christchurch, New Zealand.
Purpose:
To assess the relationship between iris color and intraocular pressure (IOP).
Design:
Population-based, cross-sectional study.
Methods:
The Blue Mountains Eye Study examined 3,654 largely Caucasian participants, aged 49 to 97 years, from 1992 to 1994. Information was collected about glaucoma risk factors, and Goldmann applanation IOP measurements were taken. Iris color was assessed by comparing the undilated appearance of each eye with three standard photographs. Participants who had previous cataract or glaucoma surgery and those using glaucoma medications were excluded.
Results:
Mean IOP measurements increased with increasing grades of iris pigmentation. After simultaneous adjustment for variables associated with IOP, mean measurements were 15.92 mm Hg for blue iris color, 16.04 mm Hg for hazel or green, 16.11 mm Hg for tan-brown, and 16.49 mm Hg for dark brown (P for trend = .001).
Conclusions:
This study demonstrates a modest but statistically significant association between increasing iris color and IOP.