Beyond CCT: Other factors may play role in IOP accuracy

LAS VEGAS — Central corneal thickness is just “the tip of the iceberg” in the true measurement of IOP, said a glaucoma specialist speaking here. Other factors such as corneal elasticity, scleral thickness and genetic variability will likely also play important roles in attaining a full understanding of IOP, said Jess T. Whitson, MD, FACS.

The Ocular Hypertension Treatment Study concluded that central corneal thickness (CCT) varies in patients and may mask a true IOP reading, Dr. Whitson said, speaking here at the Ocular Surgery News Symposium, Glaucoma: Improving Your Odds. But despite the availability of nomograms, none gives a truly accurate IOP correction factor, Dr. Whitson said.

“Take these test results with a grain of salt,” he advised.

Rather than use a nomogram that was developed based upon a few studies with a limited range of corneal thicknesses, Dr. Whitson suggested, the physician should perform pachymetry in all glaucoma patients and suspects and then categorize the cornea readings as thin, average or thick.

“Beyond CCT, other factors should be considered when determining IOP,” Dr. Whitson said. Corneal curvature, corneal edema, keratoconus and corneal elasticity are all factors that should be taken into account when looking at a patient’s IOP reading, he said.

“I really believe that we are at just the tip of the iceberg in terms of the CCT story,” he said.