Intraocular Pressure Before and After Corneal Refractive Surgery: A Prospective Comparison of Corvis ST and Ocular Response Analyzer.

Abstract

The study showed that Corvis ST's biomechanical intraocular pressure (bIOP) and ocular response analyzer's (ORA) cornea-compensated intraocular pressure (IOPcc) do not agree well, before or after photorefractive keratectomy (PRK), and may not be used interchangeably. bIOP remained unchanged after PRK. To evaluate the agreement between the biomechanically corrected intraocular pressure (bIOP) measured by the Corvis ST and the IOPcc measured by the ORA before and after PRK. In this prospective interventional study, a total of 53 patients (53 eyes) were included. Measurements were acquired using both the Corvis ST and ORA devices before and 3 months post-PRK. The agreement between the 2 devices was evaluated using limits of agreement (LoA) and Bland-Altman plots. The participants had a mean age of 29.6 ± 5.21 years (range: 21 to 40), with 41 (77.4%) of them being females. After the surgery, the average change in intraocular pressure (IOP) was 0.3 ± 1.7mm Hg for bIOP and -1.6 ± 4.0mm Hg for IOPcc. The corresponding 95% LoA were -3.5 to 4.2mm Hg and -9.5 to 6.3mm Hg, respectively. The 95% LoA between bIOP and IOPcc after PRK was -2.3 to 8.5mm Hg. Notably, the bIOP values were higher for IOPs <20mm Hg and lower for IOPs >20mm Hg compared with IOPcc. The findings indicate a weak agreement between the Corvis ST-bIOP and the ORA-IOPcc both before and after PRK. These devices may not be used interchangeably for IOP measurement. bIOP exhibited less variation compared with the IOPcc, suggesting that the bIOP may be a better option for IOP reading after PRK.