Evidence Table 16Trabeculectomy vs. pharmacological treatment

Study detailsPatientsInterventionsOutcome measuresEffect sizeComments
Burr et al., 200415

Study design:
Systematic Review

Evidence level: 1++

Duration of follow-up:
Minimum length of follow-up was 12 months.
Patient group:
POAG, NTG, pigmentary glaucoma, Pseudo- exfoliative glaucoma.

Inclusion criteria:
  • Any gender or nationality
  • >18 years only
Possible interventions:
  • Non-penetrating surgery ± MMC or 5F
  • Other surgery including drainage
  • Trans-scleral cytophotocoagulation (TSCPC)
Exclusion criteria:
Studies where medical arm included laser.

Primary Outcomes:

Progressive visual field loss according to criteria described for each trial


Quality of Life

Secondary Outcomes:

Change in IOP


Progression of optic disc or nerve fibre damage


Reduction of LogMAR score ≥ 0.3 (Snellen visual acuity ≥ 2 lines)


Adverse Events (severe/minor) including: mortality, loss of eye due to infection or inflammation, severe irreversible reduction in vision, visually significant cataract, incidence of cataract surgery, need for additional surgery or medication, transient decrease in central vision from complications, systemic side effects (cardiovascular and COPD, CNS defects), local side effects (eye irritation, watering, redness, discomfort)


Economic data

Comparison 2:
Medications v trabeculectomy

Intervention Details:
Trabeculectomy in 3 Studies. Migdal 1994 (Moorfields Trial), Jay 1988 (Glasgow trial), Lichter 2001 (CIGTS trial)

Migdal 1994 (Moorfields Trial)- miotics, Sympathomimetic or beta- blocker + oral CAI Jay 1988 (Glasgow trial) - miotics, Sympathomimetic or beta-blocker + oral CAI Lichter 2001 (CIGTS trial) – Beta blockers + other not specified.

Quality Assessment:

Selection Bias
randomisation was adequately concealed in Lichter 2001 (CIGTS trial), Jay 1988 (Glasgow trial), Migdal 1994 (Moorfields Trial),

Performance Bias - NR

Detection Bias - Assessment of outcomes was not masked for any of the Studies apart from QoL in CIGTS – telephone administered questionnaire

Attrition Bias
Jay 1988 (Glasgow trial): 25/57 in medication group and 30/50 not available for final analysis. IOP analysis not ITT
Migdal 1994 (Moorfields Trial): IOP and VF analysis not ITT.
Lichter 2001 (CIGTS trial): at 5 years 37/607 lost to follow-up. Analysis was ITT
Comparison 1: Medications v Scheie’s procedure (no longer performed)Funding: Non industry funded (Cochrane Review).
  • Includes Studies with miotics (pilocarpine).
  • Outcome assessment was not masked
  • Migdal 1994 (Moorfields) and Jay 1988 (Glasgow trial) were not ITT analyses as the treatment failures had been excluded.
Literature search date to August 2003.
An updated search was run in February 2005 but no new studies were found.

Additional Outcomes:

Optic disc change (Jay 1988)
Health related quality of life in Lichter 2001 (CIGTS trial)
Economic measures in Migdal 1994 (Moorfields Trial) Visual Acuity Loss (All studies)

Burr 2004 reported OR for VF progression for CIGTS and also Number of patients with unacceptable IOP for Moorfields but did not did not actual dichotomous outcome figures so they could not be included in the meta-analysis.

Jampel et al., 200564 paper describes perioperative complications for the CIGTS study and reports number of trabs with no augmentation = 177/465 eyes, Number with 5FU = 266/465 eyes and number with MMC = 22/465 eyes
Comparison 2: Medications v trabeculectomy
Progressive Visual Field Loss (Mean change in visual field score from baseline)Jay 1988 (Glasgow trial)
At 4.6 years mean follow-up
27/57 medical patients and 13/50 trab patients had progressed by at least one stage.

Migdal 1994 (Moorfields Trial)
Friedman Visual field analysis
3.92 (95% CI: 2.02 – 5.82) favours Trab. Signif
Humphrey automated perimetry (introduced 2yrs after start of study)
Medical: 25/40 (63%) progressed
Trab:34/48 (71%) progressed
OR:0.69 (95% CI: 0.29 – 1.67)
No significant difference

Lichter 2001 (CIGTS trial)
VF Score change from baseline – 1yr
−0.5 (95% CI: −1.10 – 0.10)
VF Score change from baseline – 5yr
0.30 (95% CI: −0.45 – 1.05)
No significant difference at 1 or 5yrs

Mean VF score difference between treatment groups over follow up time
−0.36 (95% CI: −0.67 to −0.05)
Adjusting for cataract mean VF:
−0.28 (95% CI: −0.59 to 0.03)
No significant difference

Logistic Regression (adjusting for baseline VR, age, sex, race, diagnosis, diabetes and time in study)
Risk of progressive VFL of at least 3 units from baseline between treatment groups:
OR= 0.74 (95% CI: 0.54 – 1.01)
Adjusted for cataract:
OR = 0.75 (95% CI: 0.55 – 1.02)
No significant difference
Mean reduction in IOP from baseline mmHgJay 1988 (Glasgow trial) [short term only]
6.0 (95% CI:2.64 – 9.36)
Migdal 1994 (Moorfields Trial)
Short term (51/56 Medical/Surgery)
6.2 (95% CI: 3.92 – 8.48)
Medium term (50/56 Medical/Surgery)
1.6 (95% CI: −0.69 – 3.89)
Long term (46/56 Medical/Surgery)
3.4 (95% CI: 1.04 – 5.76)
[Both above studies exclude failures from the point of failure].
Lichter 2001 (CIGTS trial)
At year one (595 pts)
3.6 (95% CI: 2.78 – 4.42)
Favours Trab Signif
At 5 years ( 384 pts)
1.9 (95% CI: 0.85 – 2.95)
Favours Trab. No significant difference.
  1. Mortality
    Jay 1988 (Glasgow trial)
    At last follow up (mean 4.6yrs) 12/112 (14%) of recruited pts died. 7in the medical group, 8 in the Trab group and 1 unknown.
  2. Severe irreversible reduction in vision
    Jay 1988 (Glasgow trial)
    At one year, 6/46 (13%) eyes in the medical group had lost central fixation and in the following 2 years, a further 2 in the same group. No pts in the Trab group lost central fixation over mean follow up of 33 months.
  3. Visually significant cataract
    Total from all Studies
    57/403 for trabeculectomy
    24/416 for medications.
    RR: 2.45 (95% CI: 1.55 to 3.87)
RCTs included in BURR 2004 that meet guideline inclusion criteria
STUDYInterventionDurationFundingPopulation Disease severitySize N - patients (eyes)Age (mean/range)Mean Baseline IOP mmHg% Afro- Caribbean/% Family HistoryCochrane Quality CheckNotes
Jay & Murray, 198865 Glasgow [UK]Trab v Medical7yrs max (mean 4.6yrs)NRNewly diagnosed POAG
65% moderate
35% severe

50 Trab
57 Meds
NRMeds: 37.8 ± NR
Trab: 37.8 ± NR
0/NRSelection: A
Detection: C
Attrition – FU: B
Attrition – ITT: C
Moderate risk of bias
Outcome assessment was not masked
Pilocarpine included in medication
Treatment failures excluded from analysis
Lichter et al., 200189 CIGTS [USA]Trab v MedicalMin 5 yrsNon industry – National Institutes of Health, National Eye Institute grants91% POAG (mean visual field defects 4.8units on a scale of 0 to 20)
C/D range 0.6–0.7
Mild glaucoma

300 Trab
307 Meds
57.5 (range 28–75)Meds: 27 ± NR
Trab: 27 ± NR
44/NRSelection: A
Detection: C
Attrition – FU: A
Attrition – ITT: A
Low risk of bias
Main medication was beta- blockers
Migdal et al., 199498 Moorfields [UK]ALT v Trab v Medical6 mths – 8 yrsCharity – Frost FoundationCOAG
29% early
23% middle
48% late

55 laser
57 Trab
56 Meds
63.5ALT: 35.0 ± 8.7
Meds: 35.0 ± 5.4
Trab: 34.0 ± 5.4
6/NRSelection: A
Detection: C
Attrition – FU: B
Attrition – ITT: C
Moderate risk of bias
Outcome assessment was not masked
Data obtained from study authors
Pilocarpine included in medications
Failure criteria ≥ 22 mmHg
Treatment failures excluded from analysis

Cochrane Quality Assessment Grades: A =Acceptable, B=Unclear, C=inadequate

Abbreviations: NR=not reported, M/F=male/female, NA=not applicable, N=total number of patients randomised, SD=Standard Deviation, CI95%= 95% Confidence Interval, ITT=Intention to Treat

From: Appendix D, Evidence tables

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