January 07, 2013
1 min read

Evolving technologies keep IOP at forefront of glaucoma diagnosis, assessment

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ATLANTIC CITY, N.J. — Innovations in tonometry provide increasingly accurate IOP readings, a speaker said here.

“The [American Academy of Ophthalmology] says you don’t need pressure as part of the definition [of glaucoma], but I would argue it’s still very important,” Leon W. Herndon, MD, said at the Current Concepts in Ophthalmology meeting.

Goldmann applanation tonometry is still the gold standard of measuring IOP, Herndon said. However, newer technologies provide more sensitive measurements.

The Pascal Dynamic Contour Tonometer, a third-generation digital contact tonometer, cradles the cornea without applanation.

“I think this is the closest thing we have to a true intraocular pressure,” Herndon said.

Dynamic contour tonometry uses ocular pulse amplitude (OPA), a dynamic reading of overall ocular rigidity.

Herndon quoted a study in which OPA was measured in 55 eyes of 32 patients. Results showed that increased OPA was associated with a decreased risk of glaucoma.

The Ocular Response Analyzer (ORA, Reichert) gives a dynamic measurement of corneal hysteresis, a measurement of the viscoelastic properties of the cornea. Goldmann tonometry relies on static applanation of the cornea, while ORA measurement hinges on movement of the cornea in response to a rapid air pulse, Herndon said.

Disclosure: Herndon serves on the speakers bureaus of Alcon, Sight Sciences and Reichert, and he is a consultant/advisor for Alcon and Sight Sciences.