ERRONEOUS CORRECTING OF IOP FOR CORNEAL THICKNESS

By Dr. Kevin -
Gunvant P, O'Leary DJ, Baskaran M, et al. Evaluation of tonometric correction factors. J Glaucoma. 2005;14(5):337-43. This study investigated the efficacy of currently available correction factors in correcting intraocular pressure (IOP) measurements for central corneal thickness variations. It states that
"the Ehlers and Orssengo and Pye models may significantly overestimate the effect of CCT on IOP measurement. Correcting IOP for the effect of CCT using these models could be erroneous and lead to overcorrection of IOP. This could result in erroneously low corrected IOP in eyes with thicker cornea and erroneously high corrected IOP in eyes with thinner cornea."

This is yet another study that demonstrates that we should be determining risk level for glaucoma using CCT and IOP separately, but not together in a "corrected IOP". Using a corrected IOP seems to be common sense, but no study demonstrates it's usefulness. I think I'll continue to treat CCT and IOP as separate risk factors, as demonstrated by the OHTS study.

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