El Sayyad 2000.

Methods	Unit of analysis: paired (1 eye per participant had DS, the other had trabeculectomy) Method of allocation: not stated Masking (outcome assessment): not stated Exclusions after randomisation: 2 participants were excluded and replaced due to conversion from DS to trabeculectomy. Losses to follow‐up: none Compliance: not stated Study design (intention‐to‐treat or available case analysis): 39 participants (78 eyes) with bilateral POAG underwent bilateral filtering surgery between October 1997 and March 1998. Participants were assigned randomly to receive DS in 1 eye and trabeculectomy in the other; the surgeries were scheduled with no more than 3 days between them. Participants were followed up to 12 months after surgery.
Participants	Country of enrolment: Saudi Arabia Number randomised: 39 participants (78 eyes) Age: 53.4 ± 9.6 years (range: 38 to 75 years) Sex: men (62.5%) Ethnicity: not stated Main inclusion criteria: patients with uncontrolled glaucoma despite maximally tolerated medications Main exclusion criteria: patients with previous ocular surgery, patients younger than 35 years of age, or those with significant posterior segment eye disorders
Interventions	Type of surgical method: DS in 1 eye and trabeculectomy in the other Use of adjuvants:  ‐5FU: 17 eyes (43.6%) in deep sclerectomy group 15 eyes (38.5%) in trabeculectomy group  ‐Goniopuncture: 4 eyes (10.3%) in deep sclerectomy group ‐Argon Suture lysis: 17 eyes(43.6%) in trabeculectomy group    Any immediate (within 2 weeks) postoperative interventions: Resuturing of the conjunctival flap was required in 1 case with leak 3 days postoperatively in the trabeculectomy group. Argon laser suture lysis was performed in the early postoperative period in 17 eyes (43.6%) in the trabeculectomy group.
Outcomes	IOP total success (final IOP ≤21 mmHg without anti‐glaucoma medications):  DS group: 31 eyes (79%) Trabeculectomy group: 33 eyes (85%) IOP qualified success (final IOP ≤ 21 mmHg with anti‐glaucoma medications):   DS group: 36 eyes (92.3%) Trabeculectomy group: 37 eyes (94.7%) IOP failure:  DS group: 3 eyes (7.7%) Trabeculectomy group: 2 eyes (5.1%) Field of vision: not stated   Optic disc: not stated Drop in visual acuity 2 lines or more:    2 eyes in the DS group and 1 eye in the trabeculectomy group showed a drop in visual acuity of 2 Snellen lines or more because of age‐related maculopathy After trabeculectomy 1 eye developed progressive cataract with the loss of 3 Snellen lines Drop in postoperative medication score: the mean number of anti‐glaucoma medications at 12 months was 0.3 ± 0.4 in the sclerectomy group and 0.27 ± 0.50 in the trabeculectomy group. This is compared to preoperative 2.4 ± 0.7 in the sclerectomy group and 2.6 ± 0.6 in the trabeculectomy group. Adverse effects: DS group: 1 case (2.6%) had conjunctival leak, 1 case (2.6%) had hyphaema and 1 case (5.1%) had iris incarceration No cases of hypotony, progressive cataract or shallow AC were reported in this group Trabeculectomy group: 1 case (2.6%) had hypotony, 3 cases (7.7%) had conjunctival leak, 3 cases (7.7%) had hyphaema, 3 cases (7.7%) had flat AC, 2 cases (5.1%) had postoperative inflammation and 1 case (2.6%) had cataract        Length of follow‐up: 12 months Exclusions and drop outs: 2 patients were excluded. No drop outs.
Notes	The trial investigators did not consider successful cases of 5‐FU and goniopuncture as qualified success
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	The authors say participants were assigned randomly but no definite method of randomisation was stated in the study
Allocation concealment (selection bias)	Unclear risk	No information about allocation concealment was given in the study
Blinding (performance bias and detection bias) All outcomes	Unclear risk	It is unclear whether the persons assessing outcome were unaware of the nature of the procedure in each eye of the participant
Incomplete outcome data (attrition bias) All outcomes	High risk	Follow‐up rates were equal in both groups ‐ however, 2 participants were excluded from the study (and replaced) because of perforation of Descemet's membrane occurring during deep sclerectomy
Selective reporting (reporting bias)	Unclear risk	Insufficient evidence to judge as high or low