Assessment Of The Agreement In Intraocular Pressure Measured By Goldmann Applanation, Rebound Tonometer And Ocular Response Analyser Among Patients Undergoing Laser Vision Correction

Corneal ablative procedures alter corneal thickness and biomechanical properties, which can significantly affect the accuracy of Intraocular pressure (IOP) measurements. This study aims to evaluate changes in IOP after refractive surgery and to compare the agreement and reliability of different tonometers, including Goldmann Applanation Tonometry (GAT), Ocular Response Analyser (ORA,Reichert Ophthalmic Instruments, Depew, NY)-corneal-compensated IOP (IOPcc), Goldmann-correlated Intraocular pressure (IOPg), and rebound tonometry (RT -Icare® ic200, Tiolat Oy, Helsinki, Finland). It further aims to evaluate higher-order aberrations (HOA) by iTrace (Tracey technologies, USA) after refractive surgery and to assess their relationship to IOP.

Tertiary care centre in South India.

95 participants undergoing refractive surgery procedures [Laser-Assisted In Situ Keratomileusis (LASIK) n:38, Surface ablation n:57] were recruited, and Corneal Hysteresis, Central Corneal Thickness (CCT) and IOP (as GAT) were measured preoperatively and at 1 month and 3 months following surgery. IOP (as IOPg, IOPcc, RT-iCare) and HOA were measured preoperatively and at 1 week, 1 month and 3 months following surgery. Short-term trends were analysed, and agreement analysis following refractive surgery was done using the intraclass correlation coefficient (ICC) and Bland-Altman analysis. P-value <0.05 was considered significant.

IOPcc and RT showed stable postoperative IOP measurements (p >0.05). At 1 and 3 months, IOPcc maintained moderate agreement with GAT (ICC=0.626; 0.462) and IOPg (ICC= 0.682; 0.590), while RT showed more fluctuation and lower agreement with GAT (ICC= 0.609; 0.364) and IOPg (ICC= 0.714; 0.438). Overall, IOPcc demonstrated more consistent inter-device agreement than RT. GAT underestimated IOP at 3 months postoperatively (p=0.002), which correlated with reduced CCT (r = 0.413, β = 0.05; R² = 0.170), suggesting ~0.5 mmHg underestimation by GAT per 10µm CCT reduction. LASIK induced greater total HOA (p=0.013), particularly coma (p=0.034) and trefoil (p=0.012). HOAs did not demonstrate a significant association with IOP changes.

Refractive surgery significantly influences the inter-method agreement of IOP measurements. IOPcc and RT exhibit greater temporal stability and reduced susceptibility to corneal alterations. GAT underestimated the IOP postoperatively; this is related to corneal stromal ablation. Our study shows that careful interpretation of postoperative IOP measurements is warranted, and IOPcc and RT may be preferred for IOP measurements following refractive surgery. LASIK induces greater HOAs than surface ablations, but HOAs are not associated with IOP measurements.