Background
Methods
Study objective
Trial design
Participant characteristics
Inclusion criteria
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Patients with a clinical diagnosis of PAC, with IOP ≤ 30 mmHg and PAS ≤ 270 °.
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Patients with PAC with multiple mechanisms based on the results of a UBM examination. (“Multiple mechanisms” is defined as PAC caused by pupillary block plus at least one non-pupillary block mechanism).
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Patients with visual acuity ≥ 20/40.
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Patients who are aged 40–75 years and of Chinese descent.
Exclusion criteria
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Patients who are unwilling or unable to provide consent to participation in the study, who are unwilling to submit to the randomization process, or are unable to return for the scheduled protocol visits.
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Patients with angle closure due to secondary causes (i.e., subluxated lens, neovascular, uveitic, traumatic and postoperative).
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Patients who have undergone previous incisional intraocular surgery or ocular laser in the study eye (LPI, LPIP, cyclodestructive procedure, and cataract surgery).
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Patients with PAC with glaucomatous neuropathy.
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Patients who have a cataract in the study eye and who anticipate having cataract surgery in the next 3 years. (The existing cataract could affect the visual field and fundus examination and it is likely that visual acuity would be < 20/40 due to the existing cataract).
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Patients using IOP-lowing drugs who do not agree to submit to the medication washout process.
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Patients who require glaucoma surgery combined with other ocular procedures, such as cataract surgery, penetrating keratoplasty, and retinal surgery), or who anticipate the need for urgent additional ocular surgery.
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Patients with other coexisting ocular diseases, such as an abnormal cornea or a corneal infection, iridocorneal endothelial syndrome, anterior segment dysgenesis, nanophthalmos, high myopia (>6.0 D), chronic or recurrent uveitis, ocular cancer, trauma, central retinal vein occlusion, central retinal artery occlusion, and retinal detachment).
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Patients with a corneal endothelium count of < 1000/mm2.
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Patients who require the long-term use of local or systemic steroids.
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Patients who are unwilling to discontinue contact lens use after surgery.
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Patients who are participating in other clinical trials.
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Pregnant or nursing women.
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Patients with severe systemic disease, such as diabetes mellitus, hypertension, end-stage cardiac disease, nephropathy, respiratory disease, and cancer.
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Patients who are allergic to pilocarpine or alcaine.
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Patients with a contraindication to laser treatment for ocular disease.
Recruitment procedure
Sample size
Randomization process
Blinding
The classification of ultrasound biomicroscopy-based angle closure
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Iris convexity: judged according to the curvature of the posterior surface of the iris, the iris bombe is defined as the location of the posterior surface of the iris above a line drawn from the iris root to the iris margin of the pupil (Fig. 2a).×
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Thickness of the peripheral iris: the thickness of the peripheral iris will be graded with reference to limbal corneal thickness and is defined as greater than half the thickness of the limbal zone of the cornea (Fig. 2b).
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Anterior rotation of the ciliary body: the anterior rotation of the ciliary body will be judged according to the direction of the axis of the ciliary body in the anterior position, with the disappearance of the ciliary groove (Fig. 2c).
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The iris bombe.
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Thickening of the peripheral iris.
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The anterior rotation of the ciliary body.
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The iris bombe plus thickening of the peripheral iris.
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The iris bombe plus the anterior rotation of the ciliary body.
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Thickening of the peripheral iris plus the anterior rotation of the ciliary body.
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The iris bombe plus thickening of the peripheral iris, plus the anterior rotation of the ciliary body.
Intervention description
Single laser peripheral iridotomy
Laser peripheral iridoplasty plus laser peripheral iridotomy
Primary outcome measures
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Acute angle-closure crisis.
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An IOP measurement taken 1 month after the laser procedure that is 8 mmHg higher than that recorded at treatment initiation.
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An IOP measurement taken 1 month after the laser procedure that is ≥ 22 mmHg when measured three times in succession.
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The progression of PAS ≥ 1 clock hour within 3 years of the laser procedure, as determined by gonioscopy.
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Glaucomatous neuropathy within 3 years of the laser procedure.
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The presence of at least two of the following symptoms: ocular or periocular pain, nausea and vomiting, blurred vision, and multicolored halos around lights (an occasional symptom).
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An IOP measurement of at least 22 mmHg, as measured by Goldmann® applanation tonometry.
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The presence of at least three of the following signs: conjunctival injection, corneal edema, a mid-dilated unreactive pupil, and a shallow anterior chamber.
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The documented progression of diffuse thinning and focal narrowing or notching of the optic disc rim.
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A cup disc ratio of ≥ 0.6.
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A cup-disc asymmetry ratio of ≥ 0.2 for similar-sized eyes or optical discs.
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Diffuse or localized abnormalities in the peripapillary retinal nerve fiber layer.
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The presence of glaucomatous visual field defect, defined as reproducible visual field defects, including nasal step, arcuate field defect, or paracentral depression in the clusters of the test sites.
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Visual field loss in the upper hemifield that is different to that in the lower hemifield.
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The absence of any other known explanation.
Secondary outcome measures
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Determining, through the administration of a questionnaire, whether or not additional medication (to control IOP) or additional surgery is required to control the progression of PAC.
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Establishing whether or not there are any changes in the best-corrected visual acuity after the laser procedure.
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Determining the number of corneal endothelium cells.
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Establishing any change in the angle width and configuration, as measured by UBM.
Safety evaluation
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Corneal injury: corneal injury will be sought via an examination by slit lamp and by conducting a corneal endothelium cell count.
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Anterior uveitis: inflammation in the anterior chamber is indicative of anterior uveitis.
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Changes in the pupil: any changes to the pupil will be established following an examination by slit lamp.
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Lens injury: lens injury will be determined following an examination by slit lamp.
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Retinal injury: a fundus examination will be conducted to evaluate whether or not retinal injury has occurred.
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Blindness: blindness will constitute a major adverse event.
Data collection and monitoring
Visit number | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 |
---|---|---|---|---|---|---|---|---|---|---|---|---|
Examination item | -7 to -1 day | Laser day | 1 W (±1 D) | 1 M (±1 W) | 3 M (±1 W) | 6 M (±1 W) | 1 Y (±2 W) | 1½ Y (±2 W) | 2 Y (±2 W) | 3 Y (±2 W) | 4 Y (±2 W) | 5 Y (±2 W) EOS |
Informed consent | X | |||||||||||
Demographics data |
X
| |||||||||||
Medical history |
X
| |||||||||||
Vital signs |
X
|
X
| X | |||||||||
Height and weight |
X
| |||||||||||
Medication record |
X
| X | X | X | X | X | X | X | X | X | X | |
Refraction |
X
b
| X | X | X | X | X | X | X | X
b
| |||
Visual acuity |
X
b
| X | X | X | X | X | X | X | X | X | X
b
| |
Slit lamp biomicroscopy |
X
b
| X | X | X | X | X | X | X | X | X |
X
b
| |
Fundus examination |
X
b
| X | X | X | X | X | X | X |
X
b
| |||
IOP (Goldmann) |
X
b
|
X
b
|
X
b
|
X
b
|
X
b
|
X
b
|
X
b
|
X
b
|
X
b
|
X
b
|
X
b
|
X
b
|
A scan |
X
b
| X | X | X | X |
X
b
| ||||||
Endothelial cell count |
X
b
| X | X | X | X | X | X |
X
b
| ||||
UBM |
X
b
| X | X | X | X | X | X | X |
X
b
| |||
AS-OCT |
(X
b
)
| (X) | (X) | (X) | (X) | (X) | (X) | (X) |
(X
b
)
| |||
Humphrey 24-2 |
X
b
| X | X | X | X | X |
X
b
| |||||
Antiglaucoma surgery | X | X | X | X | X | X | X | X | X | |||
Laser treatment | X | |||||||||||
Adverse event |
X
|
X
|
X
|
X
|
X
|
X
|
X
|
X
|
X
|
X
|
X
|
X
|