title: Laser peripheral iridotomy versus laser peripheral iridotomy plus laser peripheral iridoplasty in the treatment of multi-mechanism angle closure: study protocol for a randomized controlled trial.
abstract: China has the largest burden of primary angle-closure glaucoma (PACG) worldwide. The mechanism of the angle closure is complex and includes pupillary block and non-pupillary block. Currently, opinion is that laser peripheral iridotomy (LPI) alone is not sufficient to prevent disease progression. Laser peripheral iridoplasty (LPIP) is an alternative and effective way of widening the angle recess in eyes that are affected by primary angle closure (PAC). However, it is not known if greater benefit would be achieved using LPI plus LPIP for PAC with multiple mechanisms (MAC). Thus, the aim of this study is to demonstrate if LPI plus LPIP would be more effective than single LPI in controlling the progression of PAC with multiple mechanisms, based on ultrasound biomicroscopy (UBM) classification. A secondary aim is to determine whether or not this would result in the use of less medication and/or prolong the time to antiglaucoma surgery.
  
  
  
  This multiple-mechanism angle-closure study will comprise a 3-year, multicenter, randomized, parallel-group, open-label, superiority trial, the aim of which will be to evaluate the safety and efficacy of LPI plus LPIP versus LPI for PAC. It is anticipated that 240 adults, diagnosed with PAC (the mechanism of angle closure will be assessed by UBM and it will be determined whether or not it involves multiple mechanisms) will be recruited from ten ophthalmic centers in China. Participants will be randomly allocated to receive either single LPI or LPI plus LPIP. Participant assessment will be designed to test the rate of disease progression and who will be followed up for 3 years. The primary outcome will be the disease progression rate and a comparison will be made between the LPI and LPI plus LPIP groups using Pearson's χ2test. Logistic regression analysis will be performed to account for the central effect.
  
  
  
  If the LPI plus LPIP is found to significantly decrease the rate of PAC progression, this intervention could potentially be a standard therapy to be used to treat PAC when multiple mechanisms are involved in angle closure. Subsequently, this would have the potential to delay the rate of PAC progression to PACG and delay the time to the administration of antiglaucoma medication or trabeculectomy surgery.
  
  
  
  ClinicalTrials.gov, NCT02613013 . Registered on 24 November 2015. In fact, the study was due to start in late October 2015, however, there were no patients recruited in October, and when we registered at ClinicalTrials.gov on 5 November 2015, we received suggestions on the English translation of our protocol from the PRS Team at Clinicaltrial.gov, so the final successful registration date was on 24 November 2015.
authors.affiliation: Zhongshan Ophthalmic Center, State Key Laboratory of Ophthalmology, Sun Yat-sen University, 54 South Xianlie Road, Guangzhou, People's Republic of China.
authors.forename: Shida
authors.initials: S
authors.lastname: Chen
authors.affiliation: Hebei Provincial Eye Hospital, Xingtai City, Hebei, People's Republic of China.
authors.forename: Jianhua
authors.initials: J
authors.lastname: Lv
authors.affiliation: Handan Eye Hospital, Handan City, Hebei, People's Republic of China.
authors.forename: Sujie
authors.initials: S
authors.lastname: Fan
authors.affiliation: Department of Ophthalmology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, People's Republic of China.
authors.forename: Hong
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Department of Ophthalmology, Daping Hospital, The Third Military Medical University, Chongqing, Hubei, People's Republic of China.
authors.forename: Lin
authors.initials: L
authors.lastname: Xie
authors.affiliation: Liaoning He University, He Eye Hospital, Shenyang, Liaoning, People's Republic of China.
authors.forename: Ling
authors.initials: L
authors.lastname: Xu
authors.affiliation: Department of Ophthalmology, the Second Xiangya Hospital, Central South University, Changsha, Hunan, People's Republic of China.
authors.forename: Bing
authors.initials: B
authors.lastname: Jiang
authors.affiliation: Department of Ophthalmology, the Second Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang, People's Republic of China.
authors.forename: Huipin
authors.initials: H
authors.lastname: Yuan
authors.affiliation: Clinical and Epidemiological Research Center, the Affiliated Eye Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, People's Republic of China.
authors.forename: Yuanbo
authors.initials: Y
authors.lastname: Liang
authors.affiliation: Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology and Visual Science Key Laboratory, No. 1 Dong Jiao Min Xiang Street, Dongcheng District, Beijing, People's Republic of China.
authors.forename: Shuning
authors.initials: S
authors.lastname: Li
authors.affiliation: Department of Biostatistics, School of Public Health and Tropical Medicine, Southern Medical University, Guangzhou, Guangdong, People's Republic of China.
authors.forename: Pingyan
authors.initials: P
authors.lastname: Chen
authors.affiliation: Zhongshan Ophthalmic Center, State Key Laboratory of Ophthalmology, Sun Yat-sen University, 54 South Xianlie Road, Guangzhou, People's Republic of China. zhangxl2@mail.sysu.edu.cn.
authors.forename: Xiulan
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology and Visual Science Key Laboratory, No. 1 Dong Jiao Min Xiang Street, Dongcheng District, Beijing, People's Republic of China. wningli@vip.163.com.
authors.forename: Ningli
authors.initials: N
authors.lastname: Wang
mesh_terms: D000328:Adult; D000368:Aged; D016009:Chi-Square Distribution; D002681:China; D002985:Clinical Protocols; D018450:Disease Progression; D005260:Female; D015812:Glaucoma, Angle-Closure / Q000175:diagnosis / Q000503:physiopathology / Q000601:surgery*; D006801:Humans; D032801:Iridectomy / Q000009:adverse effects / Q000295:instrumentation*; D007498:Iris / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D053685:Laser Therapy / Q000009:adverse effects / Q000295:instrumentation*; D054023:Lasers, Semiconductor / Q000009:adverse effects / Q000627:therapeutic use*; D016015:Logistic Models; D008297:Male; D033401:Microscopy, Acoustic; D008875:Middle Aged; D013508:Ophthalmologic Surgical Procedures / Q000009:adverse effects / Q000295:instrumentation*; D020127:Recovery of Function; D012107:Research Design; D013997:Time Factors; D016896:Treatment Outcome; D014785:Vision, Ocular; D014792:Visual Acuity
keywords: LPI; LPIP; Laser peripheral iridoplasty; Laser peripheral iridotomy; PAC; PACG; Primary angle closure; Primary angle-closure glaucoma