Changes in intraocular pressure values measured with noncontact tonometer (NCT), ocular response analyzer (ORA) and corvis scheimpflug technology tonometer (CST) in the early phase after small incision lenticule extraction (SMILE).

Yang Shen,Xuejun Fang,Xiu Liu,Xiangjian Su,Huamao Miao,Xingtao Zhou

doi:10.1186/s12886-016-0381-3

Yang Shen, Xuejun Fang + Show 4 more

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https://doi.org/10.1186/s12886-016-0381-3

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Journal: BMC ophthalmology	Publication Date: Nov 18, 2016
Citations: 13	License type: cc-by

Affiliation: Eye & ENT Hospital of Fudan University

Abstract

BackgroundCorneal biomechanical properties are always compromised after corneal refractive surgeries thus leading to underestimated intraocular pressure (IOP) that complicates the management of IOP. We investigated the changes in postoperative baseline of IOP values measured with noncontact tonometer (NCT), ocular response analyzer (ORA) and corvis scheimpflug technology (CST) in the early phase after small incision lenticule extraction (SMILE).MethodsTwenty-two eyes (−6.76 ± 1.39D) of 22 moderate and high myopes, (28.36 ± 7.14 years, 12 male and 10 female) were involved in this prospective study. IOP values were measured using a non-contact tomometer (NCT-IOP), an ocular response analyzer (corneal-compensated IOP, IOPcc and Goldmann-correlated IOP, IOPg) and a Corvis scheimpflug technology tonometer (CST-IOP) preoperatively, at 20 min and 24 h, postoperatively. Repeated measures analysis of variance (RM-ANOVA), Pearson’s correlation analysis and multiple linear regression models (stepwise) were performed. Cut-off P values were 0.05.ResultsExcept for IOPcc, NCT-IOP, IOPg, and CST-IOP values significantly decreased after SMILE procedure (All P values <0.05). ΔCCT, as well as ΔMRSE and ΔKm, did not significantly correlated with ΔNCT-IOP, ΔIOPcc, ΔIOPg or ΔCST-IOP, (all P values >0.05). Multiple linear regression models (stepwise) showed that the practical post-operative IOP value was the main predictor of the theoretical post-operative NCT-IOP, IOPcc and IOPg values (all P values <0.001). The postoperative applanation time 1 (AT1) value (B = 8.079, t = 4.866, P < 0.001), preoperative central corneal thickness (CCT) value (B = 0.035, t = 2.732, P = 0.014) and postoperative peak distance (PD) value (B = 0.515, t = 2.176, P = 0.043) were the main predictors of the theoretical post-operative CST-IOP value.ConclusionsIOP values are underestimated when assessed after SMILE by using NCT-IOP, IOPg and CST-IOP. The practical postoperative IOPcc value and theoretical post-operative CST-IOP value may be more preferable for IOP assessment in the early phase after SMILE.Trial registrationCurrent Controlled Trials ChiCTRONRC13003114. Retrospectively registered 17 March 2013

Highlights

Corneal biomechanical properties are always compromised after corneal refractive surgeries leading to underestimated intraocular pressure (IOP) that complicates the management of IOP
IOP values are underestimated when assessed after small incision lenticule extraction (SMILE) by using noncontact tonometer (NCT)-IOP, IOPg and corvis scheimpflug technology (CST)-IOP
The practical postoperative IOPcc value and theoretical post-operative CST-IOP value may be more preferable for IOP assessment in the early phase after SMILE

Summary

Introduction

Corneal biomechanical properties are always compromised after corneal refractive surgeries leading to underestimated intraocular pressure (IOP) that complicates the management of IOP. We investigated the changes in postoperative baseline of IOP values measured with noncontact tonometer (NCT), ocular response analyzer (ORA) and corvis scheimpflug technology (CST) in the early phase after small incision lenticule extraction (SMILE). Corneal refractive surgeries remove corneal tissue, modify corneal shape and compromise corneal biomechanical properties leading to underestimated IOP values [3] and obscure the diagnosis of ocular hypertension. Noncontact tonometer (NCT), ocular response analyzer (ORA) and corvis scheimpflug technology tonometer (CST) are three most commonly employed instruments for clinical IOP assessment. Various confounding factors including surgical designs (i.e., flap thickness, residual stromal bed thickness, optic zone diameter and ablation depth), individual differences (i.e., age, gender, race, refractions, corneal curvature corneal hydration and postoperative wound healing response) [12] and long-term postoperative topical steroid usage make these formulas widely divergent

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