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Study Title and Description

YAG laser peripheral iridotomy for the prevention of pigment dispersion glaucoma a prospective, randomized, controlled trial.



Key Questions Addressed
1 What is the effect of peripheral iridotomy for pigmentary glaucoma?
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Primary Publication Information
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TitleData
Title YAG laser peripheral iridotomy for the prevention of pigment dispersion glaucoma a prospective, randomized, controlled trial.
Author Scott A., Kotecha A., Bunce C., Balidis M., Garway-Heath DF., Miller MH., Wormald R.
Country Glaucoma Service, Moorfields Eye Hospital, London, United Kingdom. andy.scott@ucl.ac.uk
Year 2011
Numbers Pubmed ID: 21035866

Secondary Publication Information
UI Title Author Country Year
Conversion from pigment dispersion syndrome and ocular hypertension to glaucoma in patients with a YAG peripheral iridotomy. Scott A, Kotecha A, Strouthidis NG, Bunce C, Garway-Heath DF, Wormald RP.
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Extraction Form: Peripheral iridotomy for pigmentary glaucoma 2016
Arms
Number Title Description Comments
1 Peripheral laser iridotomy iridotomy using a neodymium:yttrium–aluminum–garnet (Nd:YAG) laser
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2 No treatment
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Design Details
Question... Follow Up Answer Follow-up Answer
Study design parallel-group, randomized controlled trial
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Number randomly assigned 116 eyes of 116 participants: 57 eyes of 57 participants to laser group and 59 eyes of 59 participants to control group
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Exclusions after randomization 6 participants, 3 in each group, excluded after recruitment into the trial for not meeting inclusion criteria
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Losses to follow-up 5 participants - 2 in the laser group and 3 in the control group - withdrew immediately after randomization
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Number analyzed 116 eyes of 116 participants: 57 eyes of 57 participants to laser group and 59 eyes of 59 participants to control group
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Unit of analysis participant (1 eye per participant)
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Handling of missing data Primary analysis was an available case analysis; intent-to-treat analysis using last-observation-carried-forward was done as secondary analysis
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Sample size and power calculation 43 eyes needed per group to detect difference with 80% power at the P value < 0.05 level
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Country United Kingdom
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Mean age 48 years (range 30 to 74 years) in the laser group; 49 years (range 24 to 86 years) in the control group
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Gender 39 (68%) men and 18 (32%) women in the laser group; 42 (71%) men and 17 (29%) women in the control group
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Inclusion criteria ocular hypertension and pigment dispersion syndrome; "pigmented angles with at least 1 other feature of the following: Krukenberg's spindle, midperipheral iris, transillumination defects; backward-bowing iris configuration; reliable, full visual field tested using the Humphrey Field Analyzer 24-2 full-threshold strategy (less than or equal to 15% false positives/negatives); less than or equal to 30% fixation losses; normal glaucoma hemifield test results; AGIS score 0; IOP >21 mmHg (off treatment); visual acuity of 20/40 or better"
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Exclusion criteria other diseases leading to visual field loss; systemic medications that may alter IOP (ie, glucocorticoids, cardiac glycosides, beta-adrenergic blockers); recent ocular trauma, infection, inflammation, or surgery
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Equivalence of baseline characteristics "the groups were similar at baseline with regard to age, gender, spherical equivalent refraction, and baseline IOP"
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Laser iridotomy using a neodymium:yttrium–aluminum–garnet (Nd:YAG) laser; apraclonidine 1% instilled immediately before and after laser treatment; pilocarpine 2% and local anesthetic drops instilled before treatment; Abraham lens inserted
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Control no treatment
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Length of follow-up Planned: 3 years Actual: 3 years
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Outcomes Primary outcome, as defined by the trial: deterioration in visual field, first defined as an increase in AGIS score from 0 to 1, then revised by trial investigators to Ocular Hypertension Treatment Study criteria because the AGIS scoring system was developed for eyes with established glaucoma and may not be sensitive to detect changes in eyes with ocular hypertension (visual field abnormalities defined as a point being flagged at the P value < 0.05 level in the corrected pattern standard deviation, or having glaucoma hemifield test results outside normal limits on 3 consecutive tests, with abnormalities of the same type, index, and location in each successive field and determined independently by 2 readers) Secondary outcomes, as defined by the trial: addition of topical anti-glaucoma medications over the study period; time to start of medications if needed; and time of visual field conversion if it occurred Safety outcomes, as defined by the trial: immediate complications (transient hemorrhage, elevated IOP, or iritis), repeat laser iridotomy, retinal detachment, cataract surgery Other measurements reported in the study: Snellen visual acuity recorded at each visit
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Intervals at which outcomes assessed every 4 months for 3 years
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Information on cost of interventions or quality of life none reported
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Study period not reported
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Trial registration none reported
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Source of funding The Frost Charitable Trust, Surrey, UK; and the Special Trustees of Moorfields Eye Hospital London, United Kingdom
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Disclosures of interest "The author(s) have no proprietary or commercial interest in any materials discussed in this article"
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Subgroup analyses none reported
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Random sequence generation (selection bias):Authors' judgement Low risk
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Random sequence generation (selection bias):Support for judgement "Randomization was accomplished using a centralized computerized randomization system in the Research and Development office at Moorfields Eye Hospital using the weighted coin method"
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Allocation concealment (selection bias):Authors' judgement Low risk
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Allocation concealment (selection bias):Support for judgement "Patients were randomized after consent and were assigned study identification numbers to which only the Research and Development office had unmasked access"
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Masking of outcome assessors (detection bias)Visual field:Authors' judgement Low risk
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Masking of outcome assessors (detection bias)Visual field:Support for judgement "However, post hoc visual field analysis was performed by 2 readers masked to treatment"
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Masking of outcome assessors (detection bias)Intraocular pressure:Authors' judgement Unclear risk
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Masking of outcome assessors (detection bias)Intraocular pressure:Support for judgement "The IOP was measured by unmasked clinicians at each visit"
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Incomplete outcome data (attrition bias):Authors' judgement Low risk
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Incomplete outcome data (attrition bias):Support for judgement 11/116 (9%) participants with missing data included in the final analyses
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Selective reporting (reporting bias):Authors' judgement Unclear risk
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Selective reporting (reporting bias):Support for judgement No protocol or clinical trial registration record was available for assessment of selective outcome reporting. All outcomes mentioned in the Methods section of the published paper were reported in the Results section
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Other bias:Authors' judgement Low risk
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Other bias:Support for judgement None identified
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Results & Comparisons


Results Data
Outcome: Proportion of participants with pigment dispersion syndrome with onset of glaucomatous visual field changes      Population: All Participants
Time Point Measure Peripheral laser iridotomy No treatment


3 years

N Analyzed 52 53
Counts 8 3
Outcome: Need for additional topical medication      Population: All Participants
Time Point Measure Peripheral laser iridotomy No treatment


3 years

N Analyzed 52 53
Counts 8 9

Adverse Events
Arm or Total Title Description Proportion of adverse events Comments
Peripheral laser iridotomy Cataract cataract surgery; at 18 months for the laser group and at 34 months for the control group 1
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No treatment 1
Total 2
Peripheral laser iridotomy Retinal detachment 0
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No treatment 0
Total 0
Peripheral laser iridotomy immediate complication transient hemorrhage, elevated IOP, and iritis 0
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No treatment 0
Total 0
Peripheral laser iridotomy repeat iridotomy 2
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No treatment NA
Total 2