Characteristics of included studies

Gunning 1998
Methods	Type of study: Retrospective cohort study. Were the criteria for allocation of participants to the treatment and control groups explicitly reported? No. Criteria were not clearly defined. The authors do not explain how participants were allocated to treatment arms. Can the above criteria be explicitly related to the outcome? Yes. Patient selection could have influenced the outcome if some with a presumed better prognosis were allocated into one arm over another. Was there evidence of a consecutive sample or a clearly defined patient population or some other method to minimize the chance that clinicians preferentially selected patients with favorable outcomes or that patients with better outcomes volunteered? No evidence. No information on how patients were selected to receive the two interventions. How were the controls selected? Not explained. Was the control group representative of the underlying population? Unclear: Cannot tell from the publication. Were appropriate statistical/ case-mix methods used to adjust for confounding factors? Sample size was small, and the authors report that age, preoperative IOP, and number of preoperative ocular hypotensive medicines were not statistically significantly different. Residual confounding may have existed. There was no adjustment in the analyses. Were the factors adjusted for in the analyses, specified a priori? No adjustments were made. Was the measurement of the confounding factors in the participants consistently adequate? No. The gonioscopic appearance at baseline should have been included. Also, there is no report on the consistency of gonioscopic measurements. Was consistency achieved in allocation, administration of treatments and recording of the treatments? Unclear. Was the treatment/intervention confirmed in an objective way and not determined exclusively by self reports? Yes. The intervention was a surgical procedure. Was outcome assessment conducted in a masked fashion (if the study was prospective)? Unclear. Were criteria/protocols for outcome assessment standardized and/or pre-specified? Were there deviations from the protocol? Unclear. Was the method of outcome assessment valid? Unclear. Was outcome assessed in the same way in both groups? No – IOP assessment in lens extraction group was preceded by an oral carbonic anhydrase inhibitor and it is not clear if the IOP in this group was also obtained from diurnal curves. Losses to follow-up and reasons for loss to follow-up: controls: 0. Cases: 1 eye, which needed filtration surgery was not analyzed.
Participants	Country: The Netherlands. Study period: 1987 to 1994. Age: Mean (SD) was 66.5 (9.7) years in lens extraction group and 64.6 (11.9) years in trabeculectomy group. Gender: 61% in lens extraction group and 79% in trabeculectomy group were females. Inclusion criteria: no explicit inclusion criteria reported. Patients in lens extraction group were selected based on gonioscopic appearance as evaluated by a single author. Patients in the control group underwent trabeculectomy during the same period. Exclusion criteria: no explicit exclusion criteria mentioned. Equivalence of baseline characteristics: baseline age appears lower in controls but difference was not statistically significant. Similar in preoperative IOP values. One patient in lens extraction group had 20/200 visual acuity pre-operatively while 5 patients in trabeculectomy group had preoperative visual acuity of 20/200 or worse.
Interventions	Cases or Intervention 1 or Cases: extracapsular cataract extraction with posterior chamber intraocular lens (PCIOL). Subconjunctival steroids and pilocarpine ointment were given after the surgical procedure. Number of participants (eyes): 18 (22) Control or Intervention 2: trabeculectomy with postoperative 5-Fluorouracil administered in 6 eyes. Number of participants (eyes): 19 (25) Length of follow up: Planned: not stated. Actual: lens extraction group, range 15 to 90 months; trabeculectomy group, range 11 to 83 months.
Outcomes	Primary outcome as defined in the study: no explicit primary outcome stated a priori. Main results were focused on mean IOP. Measurement of primary outcome in the study: not clearly reported. Secondary outcomes as defined in the study: best-corrected visual acuity; postoperative anti-glaucoma medication use; visual field and gonioscopic findings. Measurement of secondary outcomes in the study: visual acuity was measured using Snellen charts, no information on measurement of visual field. Goldmann 3-mirror goniolens was used to evaluate the angle. Intervals at which outcome assessed: no specific intervals reported. Reported information on cost of interventions: none. Reported information on quality of life: none.
Notes
Risk of bias table
Item	Authors’ judgement	Support for judgement
Kubota 2003
Methods	Type of study: retrospective cohort study. Were the criteria for allocation of participants to the treatment and control groups explicitly reported? Yes, those with broad PAS in two or more quadrants had combined procedures. Can the above criteria be explicitly related to the outcome? Yes, the presence of PAS may be associated with worse IOP outcome. Was there evidence of a consecutive sample or a clearly defined patient population or some other method to minimize the chance that clinicians preferentially selected patients with favorable outcomes or that patients with better outcomes volunteered? No. How were the controls selected? The indication for an additional goniosynechialysis procedure was a broad peripheral synechiae of more than 2 quadrants observed by intraoperative Swan gonioscopy. Was the control group representative of the underlying population? Unclear. Were appropriate statistical/case-mix methods used to adjust for confounding factors? No factors adjusted for in the analysis. Were the factors adjusted for in the analyses specified a priori? None adjusted for. Was the measurement of the confounding factors in the participants consistently adequate? Unclear. Was consistency achieved in allocation, administration of treatments and recording of the treatments? Unclear. Was the treatment/intervention confirmed in an objective way and not determined exclusively by self reports? Yes, treatment was surgery. Was outcome assessment conducted in a masked fashion (if the study was prospective)? No attempt at masking outcome assessment described. Were criteria/protocols for outcome assessment standardized and/or pre-specified? Were there deviations from the protocol? No criteria described. Was the method of outcome assessment valid? Unclear, method of measurement of outcomes including IOP not described. Was outcome assessed in the same way in both groups? Unclear. Losses to follow-up and reasons for loss to follow-up: controls – none reported, but not clear if sample was consecutive. Cases – none reported, but not clear if sample was consecutive.
Participants	Country: Japan. Study period: April 1998 to March 2001. Age: Mean (SD) age of all patients was 67.7 (8.8) years. Gender: 67% of all patients were women. Inclusion criteria: PACG was defined as GON, reproducible VF defect, closed angle on indentation. Also write "patients with a closed angle who had a history of raised IOP were included in the study." Not sure if this means patients without VF defect and GON were included. Exclusion criteria: secondary angle-closure glaucoma. Equivalence of baseline characteristics: unclear
Interventions	Cases or Intervention 1 or Cases: phacoemulsification and intraocular lens replacement. Number of participants (eyes): 9 (11) Control or Intervention 2: phacoemulsification and intraocular lens replacement and goniosynechialysis. Number of participants (eyes): 2 (2) Length of follow up: planned: Not stated. Actual: 13.8 (7.2) months, range 6 to 36 months
Outcomes	Primary outcome as defined in the study: no primary outcome was specified a priori. IOP was reported. Measurement of primary outcome in the study: not reported. Secondary outcomes as defined in the study: number of postoperative medications, visual acuity, complications. Measurement of secondary outcomes in the study: visual acuity measured using Snellen charts. Intervals at which outcome assessed: during routine follow-up for surgery, 1 week, 2 weeks, 1 month, 2 months, 3 months and 6 months postoperatively. Reported information on cost of interventions: none. Reported information on quality of life: none.
Notes
Risk of bias table
Item	Authors’ judgement	Support for judgement

PACG – primary angle-closure glaucoma

IOP – intraocular pressure

SD – standard deviation

PCIOL – posterior chamber intraocular lens

GON – glaucomatous optic neuropathy

VF – visual field

PAS – peripheral anterior synechiae