This article is more than 5 years old. Information may no longer be current.
Corneal collagen cross-linking can affect accuracy of IOP measurements
Click Here to Manage Email Alerts
Performing riboflavin-UVA-induced collagen cross-linking to treat corneal ectasia may result in overestimation of true IOP measurements, according to a study by researchers in Switzerland.
"Although the magnitude of this effect was small, care should be taken when measuring IOP with [Goldmann applanation tonometry] after CCL (corneal collagen cross-linking), as it results in less accurate, much more variable IOP readings," the study authors said.
Timo Romppainen and colleagues compared IOP measurements in 10 human eye bank corneas before and after CCL with riboflavin and ultraviolet-A (UVA) irradiation. IOP was measured by Goldmann applanation tonometry, dynamic contour tonometry and by using the TonoPen XL (Medtronic). All pressure measurements were made in an artificial anterior chamber with a hydrostatically controlled reference pressure adjusted in 5-mm Hg steps, from 10 mm Hg to 40 mm Hg, according to the study.
The researchers found that before cross-linking, Goldmann tonometry and dynamic contour tonometry showed an "excellent" concordance with the manometric reference pressure, while the TonoPen overestimated the true IOP.
After cross-linking, however, the reliability of IOP readings decreased for all three methods, resulting in a slight overestimation of mean IOP, the authors reported.
"The mean difference between IOP readings after and before CCL was +1.8 mm Hg for [dynamic contour tonometry], +2.9 mm Hg for [Goldmann tonometry] and +3.1 mm Hg for [TonoPen]," they said.
The study is published in the December issue of Investigative Ophthalmology & Visual Science.