Purpose
To compare the efficacy and safety of laser peripheral iridotomy with or without laser peripheral iridoplasty in the treatment of eyes with synechial primary angle-closure or primary angle-closure glaucoma.
Design
Randomized, controlled clinical trial.
Methods
Consecutive patients older than 40 years with synechial primary angle-closure or primary angle closure glaucoma were recruited. Eligible patients were randomized to 1 of 2 treatment options, iridotomy or iridotomy plus iridoplasty, and were followed up for 1 year. Main outcome measures were intraocular pressure (IOP), peripheral anterior synechiae, corneal endothelial cell count, and complications.
Results
Seventy-seven eyes (77 patients) were randomized to the iridotomy group, and 81 eyes (81 patients) were randomized to the iridotomy plus iridoplasty group. Sixty-one patients (79.2%) in the iridotomy and 65 patients (80.2%) from the iridotomy plus iridoplasty groups completed 1 year of follow-up. There were no significant differences between the groups in the baseline data. IOP was reduced from 24.66 ± 13.76 mm Hg to 19.03 ± 6.21 mm Hg in the iridotomy group ( P < .001) and from 27.96 ± 13.06 mm Hg to 20.45 ± 7.26 mm Hg in the iridotomy plus iridoplasty group ( P < .001). Extent of peripheral anterior synechiae was decreased by 1 more clock-hour after iridoplasty compared with that after iridotomy in the iridotomy plus iridoplasty group ( P < .001). There was no significant difference in IOP, medications, need for surgery, or visual function between groups at the 1-year visit.
Conclusions
In eyes with synechial primary angle-closure or primary angle-closure glaucoma, both iridotomy alone or combined with iridoplasty provide a significant and equivalent reduction in IOP. There is also a possible reduction in peripheral anterior synechiae, more so in the iridoplasty group.
Population-based studies have suggested that the prevalence of primary angle-closure glaucoma (PACG) is higher in East Asians than in Europeans and Africans. China has the largest burden of PACG in the world and needs to address this public health problem.
Laser peripheral iridotomy (iridotomy) eliminates pupillary block and has been recommended as the initial therapy for primary angle closure and PACG. However, angle closure can occur from non–pupillary-block mechanisms such as plateau iris, lens, and other mechanisms. Iridotomy alone may not be effective in non–pupillary-block angle closure: the angles may not open after iridotomy, and such eyes are usually (incorrectly) lumped together as having plateau iris. Such cases are not unusual: Wang and associates suggested that in 61.9% of Chinese patients with angle closure, the angle closure is caused by non–pupillary-block components. He and associates reported that 19.4% of Chinese eyes with suspected primary angle closure had residual angle closure after iridotomy. Hung and Chou reported that the dark-prone provocation test results were positive (rise of 8 mm Hg or more) in 60% of Chinese eyes after iridectomy. In Choi and Kim’s series, 32.2% of eyes with peripheral anterior synechia (PAS) progressed during a mean follow-up of 34.4 months. This progression was attributed to the non–pupillary-block component of angle closure.
Several studies have reported that laser peripheral iridoplasty (iridoplasty) is a safe and simple procedure that effectively opens appositionally closed portions of the drainage angle. Our pilot study confirms Wand’s report of synechial lysis using iridoplasty.
We therefore hypothesized that in a population with a high prevalence of PACG where a significant number of patients have a mixed mechanism (pupillary and nonpupillary block) of angle closure, iridotomy followed by iridoplasty may remove the pupillary block, address the nonpupillary block components, and may even lyse some PAS, providing better intraocular pressure (IOP) control of the disease. We designed a randomized controlled trial to investigate whether iridotomy followed by iridoplasty is better than iridotomy alone in patients with synechial PAC and PACG.
Methods
The study was conducted at the Department of Ophthalmology in Handan Third Hospital (a branch of the clinical research center of Beijing Tongren Eye Center), Hebei Province, China. Consecutive cases of PAC and PACG seeking treatment at the hospital between October 1, 2005, and October 31, 2006, were invited to participate in the clinical trial.
Inclusion criteria were: (1) age 40 years or older; (2) occludable angle, defined as nonvisibility of the posterior trabecular meshwork of 270 degrees or more without indentation; (3) more than 0.5 clock hours of PAS; and (4) ability to undergo examination and laser procedures. Exclusion criteria were: (1) unwillingness or inability to provide consent, or inability to return for scheduled visits; (2) history or signs of acute angle closure (dilated and fixed pupil, sector atrophy of iris, pigmentary dusting of corneal endothelium, and glaukomflecken); (3) prior intraocular surgical treatment; (4) history or signs of trauma to the eye; or (5) any other ocular disorders that may have an effect on the structure or function of the drainage angle, such as uveitis and lens dislocation.
Based on the presence or absence of glaucomatous optic neuropathy, the patients were classified as having PACG or PAC. Eligible patients were randomized by a research assistant into 1 of 2 treatment arms (the iridotomy group or the iridotomy plus iridoplasty group) using a random number table created by SPSS statistical software (SPSS, Inc, Chicago, Illinois, USA).
All patients underwent a comprehensive ophthalmic examination including refraction, static and dynamic Goldmann gonioscopy, Goldmann applanation tonometry, fundus examination, and automated perimetry (Humphrey Field Analyzer 750i, SITA fast strategy, 24–2 threshold test; Humphrey Instrument, San Leandro, California, USA) before treatment. At each scheduled visit, visual acuity, IOP, gonioscopy, PAS extent, visual field, medical therapy, surgical interventions, corneal endothelial cell count (CECC), and complications were noted recorded.
Visual acuity was recorded based on a decimal chart and transferred into an equivalent logarithm of minimal angle of resolution scale. Counting fingers, hand movements, and light perception visual acuity were recorded as 1.5, 2.0, and 2.5 in the logarithm of minimal angle of resolution scale, respectively.
Scheduled visits were at 3 days, 1 week, 2 weeks, 1 month, 3 months, 6 months, and 12 months after the laser procedure. Additional visits were scheduled if indicated. All clinical data were documented in standard forms.
During follow-up, topical antiglaucoma medications were initiated if the IOP was more than 21 mm Hg or if repeatable visual field progression was observed. Maximum medical therapy was defined as a 3-topical drug combination. Trabeculectomy was considered if the IOP level could not be reduced to 21 mm Hg with the maximum dosage or if the patient declined to use medications. IOP, visual acuity, and medications were recorded every visit. Gonioscopy was performed after iridotomy at 3 days, 6 months, and 12 months. Automated perimetry and CECC were measured at 1 month and 12 months.
The ophthalmologists who made the diagnoses were not aware of the treatment assignment. For patients with bilateral eligible eyes, both eyes were treated with same procedure, and 1 eye was selected randomly for the final analysis. The ophthalmologist (S.J.F.) who performed the follow-up examination could not be masked to the intervention. She (S.J.F.) had a good agreement with (Y.B.L.) to determine the extent of PAS: 83.3% of 30 subjects with PAC or PACG were assessed between the 2 investigators as having less than 1 clock hour of PAS. At each visit, the examiner did not have access to the previous IOP or gonioscopy records. The technicians who performed IOP examination, refraction test, and automated perimetry also were masked to group assignment.
All laser procedures were performed by 2 senior glaucoma specialists (S.J.F., W.R.L.) on an outpatient basis. Before laser treatment, 2% pilocarpine was applied topically to stretch the iris. Iridotomy was performed under topical anesthesia with a neodymium:yttrium–aluminum–garnet laser (YL-1600; NIDEK Co, Ltd, Aichi, Japan) using an Abraham contact lens (Ocular Instruments, Inc, Bellevue, Washington, USA). A treatment site was selected in the superior nasal iris or in a crypt, where present. Treatment was initiated with a single 4-mJ pulse, and the power was increased until patency was achieved. We tried to achieve a 0.2-mm opening, and patency was determined by direct visualization of the posterior chamber.
Iridoplasty was performed with a frequency-doubled Q-switched neodymium:yttrium–aluminum–garnet 532-nm laser (GYC-2000, DPSS LASER 532 nm; NIDEK Co, Ltd) 2 to 5 days after iridotomy. The initial level of laser energy was 300 to 500 mW. The duration of each laser pulse was 0.4 to 0.5 second, with a spot size of 150 to 200 μm. The beam was aimed at the most peripheral portion of the iris as possible, starting from the connection of angle in those with PAS and those without PAS. The laser energy level was increased if there was no localized iris contraction at the treated area. The power was reduced if bubble formation or pigment release occurred. Treatment consisted of approximately 20 to 24 spots over 360 degrees, leaving approximately 2-spot diameters between each spot and avoiding large visible radial vessels where possible.
IOP was tested at 1 and 2 hours after laser therapy. Appropriate treatment was provided for IOP spikes of more than 30 mm Hg. The treated eye was maintained on 1% topical pilocarpine and TobraDex (0.3% tobramycin and 0.1% dexamethasone; Alcon Laboratories, Fort Worth, Texas, USA) 4 times daily for 3 days.
Sample Size and Statistical Analysis
A sample size of 63 in each group was required to detect a 2.5-mm Hg difference in IOP (standard deviation [SD], 5 mm Hg) between the groups, with a power of 0.8 and type I error of 0.05. Taking into account a 20% loss to follow-up, 76 cases needed to be recruited in each group.
Statistical Analysis System software version 9.1.3 for Windows (SAS Institute, Cary, North Carolina, USA) was used for the analysis. Data from the 1-year follow-up visit were used for analysis. The means and SDs were calculated the continuous variables: age, IOP, corneal thickness, and CECC. The median and 25% to 75% quartile range were calculated for data with nonnormal distributions, such as best-corrected visual acuity (BCVA), PAS, and cup-to-disc ratio. Statistical significance was determined using the Student t test (normal distribution) or rank-sum test (nonnormal distribution). The chi-square test was used to test the statistical significance of the categorical data. P < .05 was considered to be statistically significant (2-sided). An analysis on the last observation carried forward was used to evaluate the influence of loss to follow-up.
Results
Demographic and Baseline Data
Between October 1, 2005, and October 31, 2006, a total of 174 consecutive patients with PAC or PACG and PAS were eligible for the study. Sixteen patients (9.2%) did not provide informed consent and were excluded. One hundred fifty-eight (90.8%) were recruited and randomized to receive iridotomy (77 patients) and iridotomy plus iridoplasty (81 patients). Of these, 126 patients completed 1 year of follow-up: 61 (79.2%) from the iridotomy group and 65 (80.2%) from the iridotomy plus iridoplasty group.
Table 1 summarizes the demographic and baseline data of the 126 patients. There were no statistically significant differences in gender, age, presenting IOP, corneal thickness, BCVA, PAS, mean deviation (MD), cup-to-disc ratio, and CECC between the groups.
| Iridotomy Group (n = 61) | Iridotomy + Iridoplasty Group (n = 65) | P Value | |
|---|---|---|---|
| Female-to-male ratio | 41:20 | 34:31 | .088 a |
| Mean age ± SD (yrs) | 63 ± 8 | 65 ± 8 | .063 b |
| Mean presenting IOP ± SD, mm Hg | 26.23 ± 14.63 | 29.07 ± 13.20 | .254 b |
| Mean corneal thickness, mm | 543.57 ± 31.02 | 546.98 ± 32.11 | .499 b |
| Median of presenting BCVA (quartile range), logMAR | 0.15 (0.00 to 0.30) | 0.15 (0.00 to 0.50) | .410 c |
| Median of presenting PAS (quartile range), clock hours | 4.50 (1.50 to 8.00) | 5.00 (3.00 to 9.25) | .193 c |
| Presenting MD (%) | |||
| ≤6 dB | 30 (49.2) | 38 (43.1) | .700 a |
| >6 and <12 dB (%) | 6 (9.8) | 9 (13.8) | |
| ≥12 dB (%) | 25 (41.0) | 28 (43.1) | |
| Presenting C/D (range) | 0.50 (0.30 to 0.80) | 0.50 (0.30 to 0.85) | .362 c |
| Mean presenting CECC ± SD, /mm 2 | 2667.62 ± 379.65 | 2641.14 ± 346.70 | .683 b |
Clinical Outcomes
IOP was reduced from 26.23 ± 14.63 mm Hg to 19.57 ± 6.60 mm Hg in the iridotomy group ( P < .001) and from 29.07 ± 13.20 mm Hg to 21.27 ± 7.67 mm Hg in the iridotomy plus iridoplasty group ( P < .001). The final IOP and difference in reduction in IOP were not significantly different between the groups ( P = .187, P = .312). There was no statistically significant difference in medications, PAS extent, need for surgery, BCVA, or MD ( Table 2 ).
| Clinical Outcomes | Iridotomy Group (n = 61) | Iridotomy + Iridoplasty Group (n = 65) | P Value |
|---|---|---|---|
| Mean IOP ± SD, mm Hg) | 19.57 ± 6.60 | 21.27 ± 7.67 | .187 a |
| Median of IOP reduction (quartile range), mm Hg | 3.0 (–1.0 to 10.7) | 5.0 (–0.5 to 17.6) | .312 b |
| Medications (%) | |||
| 0 | 38 (62.3) | 35 (53.8) | .581 c |
| 1 | 5 (8.2) | 9 (13.8) | |
| 2 | 4 (6.5) | 7 (10.8) | |
| 3 | 14 (23.0) | 14 (21.5) | |
| Median of PAS (quartile range), clock hours | 2.00 (0.00 to 5.00) | 2.50 (0.75 to 6.00) | .473 b |
| Requirement for surgery (%) | 14 (23.0) | 18 (27.7) | .541 c |
| Median of BCVA (quartile range), logMAR | 0.20 (0.00 to 0.30) | 0.20 (0.10 to 0.35) | .431 b |
| MD (%) | |||
| ≤6 dB | 34 (55.7) | 33 (50.8) | 0.674 c |
| 6 dB < MD < 12 dB | 4 (6.6) | 7 (10.8) | |
| ≥12 dB | 23 (37.7) | 25 (38.5) |
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