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People with lighter irides have tendency for lower IOP
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CHRISTCHURCH, New Zealand — People with light irides have lower intraocular pressure than people with darker irides, according to a large population-based cohort study. Iris color appears to be an ocular determinant of IOP, authors note.
Paul Mitchell, MD, PhD, FRANZCO, and others here analyzed data from the Blue Mountains Eye Study to correlate iris color with IOP levels. This study included 3,251 participants between the ages of 49 and 97. Exclusion criteria included prior cataract or glaucoma surgery, signs of pigmentary glaucoma or pigment dispersion or current use of glaucoma medications.
IOP was measured using applanation tonometry. Iris color was qualified as blue, green or hazel, tan-brown or dark brown.
Of the 3,251 qualified participants, 1,618 had blue eyes; 907 had hazel or green eyes; 401 had tan-brown eyes; and 325 had dark brown eyes.
Even after adjusting for age and gender, mean IOP increased with increasing iris pigmentation. Multivariate-adjusted mean IOP levels were 15.92 mm Hg for people with blue eyes; 16.04 mm Hg for people with hazel or green eyes; 16.11 mm Hg for people with tan-brown eyes; and 16.49 mm Hg for people with dark brown eyes.
“The underlying pathogenesis of the relationship between iris color and IOP is not known,” authors wrote in the March issue of American Journal of Ophthalmology.