title: 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).
abstract: BACKGROUND
  Corneal 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).
  
  
  METHODS
  Twenty-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.
  
  
  RESULTS
  Except 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.
  
  
  CONCLUSIONS
  IOP 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.
  
  
  BACKGROUND
  Current Controlled Trials ChiCTRONRC13003114 . Retrospectively registered 17 March 2013.
authors.affiliation: Key Lab of Myopia, Ministry of Health, P.R. China, 19 Baoqing Road, Shanghai, 200031, China.|Department of Ophthalmology, EYE & ENT Hospital of Fudan University, Shanghai, China, 83 Fenyang Road, Shanghai, 200031, China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Shen
authors.affiliation: Shenyang Aier Eye Hospital, 11 Shiyiwei Road, Shenyang, Liaoning Province, 110000, China.
authors.forename: Xiangjian
authors.initials: X
authors.lastname: Su
authors.affiliation: Shenyang Aier Eye Hospital, 11 Shiyiwei Road, Shenyang, Liaoning Province, 110000, China.
authors.forename: Xiu
authors.initials: X
authors.lastname: Liu
authors.affiliation: Key Lab of Myopia, Ministry of Health, P.R. China, 19 Baoqing Road, Shanghai, 200031, China.|Department of Ophthalmology, EYE & ENT Hospital of Fudan University, Shanghai, China, 83 Fenyang Road, Shanghai, 200031, China.
authors.forename: Huamao
authors.initials: H
authors.lastname: Miao
authors.affiliation: Shenyang Aier Eye Hospital, 11 Shiyiwei Road, Shenyang, Liaoning Province, 110000, China. fangxuejun@vip.163.com.
authors.forename: Xuejun
authors.initials: X
authors.lastname: Fang
authors.affiliation: Key Lab of Myopia, Ministry of Health, P.R. China, 19 Baoqing Road, Shanghai, 200031, China. doctzhouxingtao@163.com.|Department of Ophthalmology, EYE & ENT Hospital of Fudan University, Shanghai, China, 83 Fenyang Road, Shanghai, 200031, China. doctzhouxingtao@163.com.
authors.forename: Xingtao
authors.identifier: http://orcid.org/0000-0002-3465-1579
authors.initials: X
authors.lastname: Zhou
mesh_terms: D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D001696:Biomechanical Phenomena; D003315:Cornea / Q000502:physiology*; D005260:Female; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology*; D008297:Male; D009216:Myopia / Q000503:physiopathology / Q000601:surgery*; D013508:Ophthalmologic Surgical Procedures; D011184:Postoperative Period; D011446:Prospective Studies; D014065:Tonometry, Ocular / Q000379:methods*; D055815:Young Adult
keywords: Corneal biomechanical property; Corneal deformation parameter; Corvis scheimpflug technology tonometer; Intraocular pressure; Ocular response analyzer; Small incision lenticule extraction