Purpose:
To evaluate, using Goldmann and Pascal tonometers, the effect of collagen corneal crosslinking on intraocular pressure (IOP) measurement in patients with keratoconus.
Methods:
A prospective interventional study was done. It was evaluated 12 patients (17 eyes) with keratoconus, of whom eight (66.7%) were females and four (33.3%) males. The mean age was 24.4±9.1 year-old. It was analyzed the intraocular pressure by Goldmann and Pascal® tonometers, and central corneal pachymetry before and one month after the corneal crosslinking (CXL) with riboflavin 0.1% and ultraviolet A for 30 minutes.
Results:
There was statistically significant increase in the mean IOP one month after CXL, with both tonometers. The increase in the means were 2.4±0.4 mmHg and 2.9±0.7 mmHg for Goldmann (P= 0.0053) and Pascal (P=0.0001), respectively. There was no statistically significance on pachymetry in both moments analyzed, with the means of 481,1±42,8 µm on the first moment, and 481,6±37,4 µm one month after the corneal crosslinking (P=0,8852).
Conclusions:
The increased IOP could be caused by an increase in corneal rigidity. However, one cannot exclude the possibility that the "true" IOP increased after CXL. This possibility could be verified through comparison between these tonometers and an invasive method of IOP measurement in eyes with keratoconus after corneal crosslinking. Although the crosslinking be considered a safe method, one can not exclude the possibility of a trabecular meshwork collagen crosslinking as a possible etiology.
Keywords: cornea: stroma and keratocytes • intraocular pressure • keratoconus