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Study Title and Description

Effect of a YAG laser iridotomy on intraocular pressure in pigment dispersion syndrome.



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 Effect of a YAG laser iridotomy on intraocular pressure in pigment dispersion syndrome.
Author Gandolfi SA., Vecchi M.
Country Glaucoma Service, University of Parma, Italy.
Year 1996
Numbers Pubmed ID: 8874444

Secondary Publication Information
UI Title Author Country Year
A 10-year follow-up to determine the effect of YAG laser iridotomy on the natural history of pigment dispersion syndrome: a randomized clinical trial. Gandolfi SA., Ungaro N., Tardini MG., Ghirardini S., Carta A., Mora P. Ophthalmology Unit, Department of Biological, Biotechnological, and Translational Sciences, University of Parma, Parma, Italy. 2014
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Effect of a YAG-laser iridotomy on intraocular pressure in the pigment dispersion syndrome. A two years follow up. Gandolfi SA, Vecchi M. 1995
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YAG laser iridotomy in pigment dispersion syndrome: 10 years later. Ungaro N, Sangermani C, Vecchi M, Cimino L, Tardini M, Gandolfi SA. 2003
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Extraction Form: Peripheral iridotomy for pigmentary glaucoma 2016
Arms
Number Title Description Comments
1 Peripheral laser iridotomy iridotomy with an yttrium–aluminum–garnet (YAG) laser
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2 No treatment
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Design Details
Question... Follow Up Answer Follow-up Answer
Study design paired-eye, randomized controlled trial
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Number randomly assigned 52 eyes of 26 participants; the fellow eye of each participant was the control
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Exclusions after randomization none reported
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Losses to follow-up 5 participants; 1 participant died in a motor vehicle accident and 4 participants requested an iridotomy in the fellow eye at an outside clinic
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Number analyzed 42 eyes of 21 participants
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Unit of analysis eye (both eyes per participant)
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Handling of missing data excluded from analysis
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Sample size and power calculation Trial authors reported that the analyzed sample size was adequate to reveal a difference of 45% in IOP with 95% power and type I error of 0.05. This seems to be post hoc power calculation, but no clear information is available
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Country Italy
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Mean age not reported (range 19 to 60 years); not reported by group
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Gender 14 (67%) men and 7 (33%) women; not reported by group
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Inclusion criteria referral to the authors' glaucoma service and diagnosed with pigment dispersion syndrome in both eyes. Diagnosis was made if pigment was deposited on the corneal endothelium in both eyes, at least 1 slit-like mid-peripheral transillumination defect was noted in the iris of both eyes, brownish pigment was deposited on the angle structures at greater than 270 degrees for both eyes, IOP was less than 18 mmHg in both eyes, pigment was liberated into the anterior chamber with topical phenylephrine in both eyes, visual field defects were absent in both eyes
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Exclusion criteria not reported
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Equivalence of baseline characteristics not reported
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Laser iridotomy with an yttrium–aluminum–garnet (YAG) laser, after which each participant was administered 1 drop of dexamethasone and 1 tablet of 250 mg acetazolamide
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Control no treatment
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Length of follow-up Planned: 2 years Actual: 2 years, with extended follow-up at 10 years
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Outcomes Primary outcome, as defined by the trial: proportion with "stable IOP," defined as IOP not increasing more than 5 mmHg; IOP calculated as an average of the 2 highest readings from the diurnal curve by Goldmann applanation tonometry Secondary outcomes, as defined by the trial: difference in IOP between treated eye and untreated fellow eye vs age; difference in IOP between treated eye and untreated fellow eye vs refractive error; refraction measured after cycloplegia (1% tropicamide, 1 drop every 5 minutes for 15 minutes) Safety measures, as defined by the trial: loss of visual acuity, lens transparency, and visual field; progression of optic nerve head damage
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Intervals at which outcomes assessed every 6 months for 2 years, and at 10 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 research grants from M. U. R. S. T., Rome, Italy
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Disclosures of interest "The authors have no proprietary interest in any of the materials used in this study"
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Subgroup analyses none reported; however, age and refractive error were plotted against IOP change for assessment of correlation
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Random sequence generation (selection bias):Authors' judgement Unclear risk
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Random sequence generation (selection bias):Support for judgement Method of randomization not reported. "An iridotomy was performed by the same investigator (SAG) in the randomly chosen eye after instillation of one drop of 0.2% dexamethasone"
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Allocation concealment (selection bias):Authors' judgement Unclear risk
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Allocation concealment (selection bias):Support for judgement Method of allocation concealment not reported
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Masking of outcome assessors (detection bias)Visual field:Authors' judgement Unclear risk
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Masking of outcome assessors (detection bias)Visual field:Support for judgement Masking of visual field examiners not reported
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Masking of outcome assessors (detection bias)Intraocular pressure:Authors' judgement Low risk
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Masking of outcome assessors (detection bias)Intraocular pressure:Support for judgement "The follow-up was performed by measuring ("masked observer") the daily IOP curve (from 8:00 AM to 6:00 PM, 6 readings, 1 reading every 2 hours) every 6 months"
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Incomplete outcome data (attrition bias):Authors' judgement High risk
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Incomplete outcome data (attrition bias):Support for judgement Excluded data from 5 of 26 (19%) participants, 4 of which were based on treatment group
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Selective reporting (reporting bias):Authors' judgement High risk
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Selective reporting (reporting bias):Support for judgement The 10-year results paper specified safety outcomes (visual acuity, lens transparency, optic nerve head, and visual field) that were not reported in the 2-year results paper. Further, visual acuity and optic nerve head outcomes were not reported in the 10-year results paper
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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: Intraocular pressure      Population: All Participants
Time Point Measure Peripheral laser iridotomy No treatment


2 years

N Analyzed 21 21
Counts 1 11


10 years

N Analyzed 21 21
Counts 3 13
Outcome: Pigment accumulation in the trabecular meshwork and on the iris      Population: All Participants
Time Point Measure Peripheral laser iridotomy No treatment


10 years

N Analyzed 21 21
Counts 0 0
Outcome: Need for additional topical medication      Population: All Participants
Time Point Measure Peripheral laser iridotomy No treatment


2 years

N Analyzed
Counts


10 years

N Analyzed
Counts
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


10 years

N Analyzed
Mean
SD
SE
Outcome: Visual acuity      Population: All Participants
Time Point Measure Peripheral laser iridotomy No treatment


2 years

N Analyzed
Mean
SD
SE


10 years

N Analyzed
Mean
SD
SE
Outcome: Change in anterior chamber depth      Population: All Participants
Time Point Measure Peripheral laser iridotomy No treatment


2 years

N Analyzed
Mean
SD
SE


10 years

N Analyzed
Mean
SD
SE
Outcome: Change in iris configuration      Population: All Participants
Time Point Measure Peripheral laser iridotomy No treatment


2 years

N Analyzed
Mean
SD
SE


10 years

N Analyzed
Mean
SD
SE
Outcome: Change in aqueous melanin granules      Population: All Participants
Time Point Measure Peripheral laser iridotomy No treatment


2 years

N Analyzed
Mean
SD
SE


10 years

N Analyzed
Mean
SD
SE
Outcome: Quality of life      Population: All Participants
Time Point Measure Peripheral laser iridotomy No treatment


2 years

N Analyzed
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10 years

N Analyzed
Mean
SD
SE

Adverse Events
Arm or Total Title Description Proportion of adverse events Comments
Peripheral laser iridotomy Major side effects by 2 years follow-up 0
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No treatment 0
Total 0
Peripheral laser iridotomy Early postoperative ocular inflammation and persistent ocular inflammation following the procedure number not reported, but cases were mild and subsided within a few days with topical steroids
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No treatment
Total
Peripheral laser iridotomy Cataract worsening of lens transparency 2
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No treatment 2
Total 4