Intraocular Pressure Accuracy Post-Myopic Laser in situ Keratomileusis: Pivotal Study Results, Standard vs Correcting Applanation Tonometry Surface Goldmann Tonometry

Khin P Kilgore,1,2 Sean McCafferty,1– 3 Jason Levine1,2 1University of Arizona College of Medicine, Department of Ophthalmology, Tucson, AZ, USA; 2Arizona Eye Consultants, Tucson, AZ, USA; 3University of Arizona College of Optical Science, Tucson, AZ, USACorrespondence: Sean McCafferty, Email [email protected]: Quantify clinical differences between standard and Correcting Applanation Tonometry Surface (CATS) Goldmann prism intraocular pressure (IOP) measurements in myopic laser in situ keratomileusis (LASIK) subjects and validate the CATS prism’s accuracy using manometric comparisons in myopic LASIK cadaver eyes.Design: Prospective cross-sectional cohort study and in vitro cohort comparison. One hundred ninety-eight eyes were enrolled from 100 subjects previously having undergone myopic LASIK. Separately, 18 enucleated globes that previously had undergone myopic LASIK were examined.Methods: LASIK subjects were enrolled from 3 investigative sites, obtaining IOP measurements by Goldmann with standard and CATS prisms per international standard organization (ISO) standardized procedures. Intraocular pressure measurements were taken using 18 enucleated LASIK globes at the manometric pressures between 5 and 50 mmHg.Outcome Measures: Statistically demonstrate the CATS prism IOP measurement is higher and more accurate compared to intracameral pressure in LASIK-treated cadaver eyes than the standard prism. Clinical validation of higher (CATS) IOP measurements compared to the standard prism in live LASIK subjects.Results: In vivo, the mean IOP difference (CATS minus standard) was +1.50 ± 2.13 mmHg (p< 0.0001), indicating standard prism underestimation post-LASIK. In cadaver eyes, the CATS prism consistently measured closer to true intracameral pressure (5– 50 mmHg, p< 0.0001), with mean differences ranging from +1.2 to +1.8 mmHg. No difference in prism measurement variability were noted (p> 0.05).Discussion: The CATS prism yields higher, more accurate IOP readings than the standard prism in myopic LASIK patients, aligning closely with intracameral pressure. Prior cadaver and clinical studies confirmed equivalence of the two prisms in healthy corneas (non-LASIK). Clinically, the CATS prism enhances ocular hypertension detection in LASIK patients, potentially reducing undiagnosed glaucoma risk.Conclusion: Findings may extend to other refractive surgeries or thin-cornea populations, warranting further study. Adoption of the CATS prism could refine postoperative IOP monitoring, impacting practice guidelines and patient outcomes.Précis: Standard Goldmann tonometry underestimates intraocular pressure (IOP) after myopic LASIK, while a CATS prism improves accuracy, validated by intracameral pressure in LASIK cadaver eyes.Plain Language Summary: Measuring accurate eye pressure is critical to determining glaucoma risk. The LASIK procedure has been shown to falsely reduce pressure measurements. A CATS modification to the standard eye pressure measurement device yields a more accurate assessment of glaucoma in those who have had LASIK eye surgery.Keywords: tonometry, LASIK, IOP, corneal biomechanics, glaucomatous optic neuropathy, glaucoma