The relationship among race, iris color, central corneal thickness, and intraocular pressure

Academic Article


  • PURPOSE. Central corneal thickness (CCT) influences applanation intraocular pressure (IOP) measurement. The present study sought to determine whether iris color might represent a qualitative surrogate for CCT or race, and therefore differential risk for elevated IOP and, consequently, developing glaucoma. METHODS. Eligible patients included those with best-corrected visual acuity (BCVA) better than 20/40 and who had not worn contact lenses within 24 hours. Exclusion criteria were prior ophthalmic surgery, topical ocular or systemic medication that would influence IOP, previous ocular inflammatory conditions, or current treatment for ophthalmic treatment. Data collection included demographic (name, date of birth, race), BCVA, and iris color. Iris color was judged according to a purpose-developed chart (white: blue, green, brown or black: brown) and patients were assigned to one of four groups. Goldmann applanation tonometry and pachymetry measurements were performed consecutively. To attain a power of 90% to find a difference of 40 μm with alpha <0.05, we examined at least 14 subjects (28 eyes) for each group. RESULTS. Comparing pachymetry measurements among iris colors revealed no statistically significant difference among the three groups of whites: blue (552 μm), green (552 μm), and brown (562 μm). The same held true when comparing IOP and CCT-adjusted IOP with iris color: blue-15.2, 15.1, green-15.4, 15.2, and brown-14.7, 14.0. When comparing CCT between whites and blacks, CCT was significantly thinner in blacks (533 μm), whether evaluating all whites (555 μm, p = 0.03) or comparing only the brown-iris white group with the black group (562 μm vs. 533 μm, p = 0.03). Mean CCT-adjusted IOP was barely significantly different between whites (14.8) and blacks (16.7) (p = 0.04). CONCLUSION. These results suggest that iris color is not associated with CCT and apparently iris color does not influence measured IOP. We were able to establish a relationship between race and IOP when adjusting IOP for CCT. Our data show a significantly higher CCT-adjusted IOP for blacks than whites demonstrating a racial difference in CCT-corrected IOP. Copyright © 2006 American Academy of Optometry.
  • Published In

    Digital Object Identifier (doi)

    Author List

  • Semes L; Shaikh A; Mcgwin G; Bartlett JD
  • Start Page

  • 512
  • End Page

  • 515
  • Volume

  • 83
  • Issue

  • 7