Study: Corneal thickness varies between black and white patients

THOROFARE, N.J. — Black patients have thinner central corneas than white patients, according to results of an ancillary study performed as part of the Ocular Hypertension Treatment Study. This finding may affect the classification of patients with ocular hypertension and the attribution of patient risk for developing glaucoma, said James Brandt, MD.

The study found differences in central corneal thickness between black study participants and their white counterparts are due to racial difference, as well as factors that may be associated with race that the study authors did not measure. What is unclear, according to the study, is whether the racial difference is unique to a patient’s ocular hypertension or if the racial difference holds for the normal population.

“It occurred to us that one of the issues might be that [blacks] have thinner corneas than age- and sex-matched whites and this may mean we are erroneously under-reading what their true pressures are,” Dr. Brandt said.

“In other words, if patients have elevated IOP and thick corneas but normal visual fields and discs, their risk of glaucoma damage is probably low,” he continued. “Their high IOP is probably an artifact of their thick corneas and it's probably wrong to commit them to a lifetime of unnecessary treatment.”

Participants in the original study had untreated IOPs between 24 mm Hg and 32 mm Hg in at least one eye and an IOP between 21 mm Hg and 32 mm Hg in the other eye. Of the 1,636 participants in the study, 409 (25%) were black.

The researchers found a statistically significant difference of 23 µm (P = .001) between central corneal thickness of black patients and white patients. Additionally, black patients who reported systemic hypertension had thinner central corneas compared with black patients without systemic hypertension.

More details on the ancillary study can be found in the March 15 print edition of Ocular Surgery News.