Abstract
Purpose:
Intraocular pressure (IOP) measurement in pathologic corneas or after corneal surgery is still a challenge. We compared IOP measurements after Intrastromal Corneal Ring Segments (ICRS) implantation using Goldmann applanation tonometry (GAT), Tonopen, Pascal Dynamic Contour Tonometer (DCT), Rebound Tonometry Icare Pro and Ocular Response Analyzer (ORA) and analyzed the influence of corneal variables measured using Pentacam.
Methods:
Clinical study evaluating 58 eyes of 51 patients with corneal ectasia wearing ICRS during at least 6 months.<br /> Bland-Altman plots were constructed to determine the agreement between different tonometers. Multivariate linear regression analysis (MLRA) was used to evaluate the influence of corneal variables on IOP measurements.
Results:
Bland Altman plots revealed good agreement between the different pairs of tonometers. Mean differences were GAT-Tonopen -0.57 mmHg (-7.43; 6.28), GAT-DTC -0.94 mmHg (-8.13; 6.24), GAT-Icare Pro -0.02 mmHg (-6.17; 6.21), GAT-Air IOP cc 1.90 mmHg (-5.25; 9.06) and GAT-Air IOP g 5.80 mmHg (-0.78; 12.38)<br /> MLRA highlighted that GAT and Icare Pro IOP were significantly affected by age (BGAT=0.435) (BIcare Pro=0. 456); and apex corneal thickness (ACT) (BGAT=0.279) (BIcarePro=0.361); GAT was also affected by Corneal Astigmatism (CA) (BGAT=0.396); R2 of 0.431and 0.347 respectively. DTC was only influenced by age (BDTC=0. 359) R2 of 0.099. ORA AirIOPcc and AirIOPg were significantly affected by ACT, Thinnest corneal thickness (TCT) and Corneal curvature (CC) R2 of 0.465 and 0.486 respectively. Tonopen was the only tonometer that presented independence of all parameters studied.<br />
Conclusions:
DCT and IOPcc present good concordance with GAT, while Icare Pro and Tonopen's is excelent. Since Tonopen is not affected by corneal parameters, it could be the best choice in patients with ICRS