Da Pozzo 2006.

Study characteristics
Patient Sampling	Patients were selected among those referred to the Glaucoma Unit at Trieste University Eye Clinic between January and October 2004 for periodic scheduled visit. Healthy participants were recruited among staff members, friends or spouses of patients, or normal volunteers. One eye per person was randomly selected.
Patient characteristics and setting	Sample size: 110 eyes of 110 participants (48 glaucoma and 62 healthy controls). Age: glaucoma patients mean ± SD, 66.8 ± 8.8 years; controls 64.7 ± 6.5 years. Country: Italy. Ocular comorbidities: no corneal or lens opacity, BCVA < 20/40, SE > ± 4 D, peripapillary atrophy falling under ellipse measurement, tilted disc, uveitis, significant vitreous floaters, or diffuse/localised retinal or macular disease. Setting: Glaucoma Unit, Trieste University Eye Clinic. Spectrum of glaucoma severity: mean ± SD MD and PSD on the VF test were ‐1.74 ± 1.69 dB and 3.56 ± 1.5 dB. Control participants: normal VF result (MD and PSD within 95% confidence limits, GHT within normal limit), IOP < 21 mmHg, and healthy optic disc with intact neuroretinal rim.
Index tests	Scanning Laser polarimetry: GDx VCC (software 5.3.4; Carl Zeiss Meditec, CA, USA). The correct positioning of ellipse on inner margin of peripapillary scleral ring was rechecked on all eyes by a trained technician. Scans with evidence of atypical pattern on the printout retardation map or a score < 7 on the 4‐scan quality checks performed by software (alignment, fixation, refraction and illumination) were excluded. No details about authors' conflict of interest were reported.
Target condition and reference standard(s)	Manifest glaucoma: glaucomatous optic disc appearance(cupping, rim notching, or diffuse thinning) and reproducible VF defects (defined as GHT outside normal limits or PSD with P < 5%). Visual field testing: Humphrey Field Analyzer, 24‐2 SITA‐standard strategy (Humphrey Systems, Dublin, CA, USA). VF reliability criteria included fixation losses and false‐positive and false‐negative rates of < 20%. Optic disc evaluation: stereo biomicroscopy with the aid of a +90 D lens after pupil dilation.
Flow and timing	Time interval between reference standard and index test was within 2 months. 14 patients were excluded for poor imaging quality: 6 presented atypical patterns on the retardation map, 2 did not pass the 4‐scan quality check, 3 saw their RNFL readings flagged as “incompatible with normative database” and 3 had poor fixation.
Comparative
Notes	None.
Methodological quality
Item	Authors' judgement	Risk of bias	Applicability concerns
DOMAIN 1: Patient Selection
Was a consecutive or random sample of patients enrolled?	Unclear
Was a case‐control design avoided?	No
Did the study avoid inappropriate exclusions?	Yes
Could the selection of patients have introduced bias?		High risk
Are there concerns that the included patients and setting do not match the review question?			High
DOMAIN 2: Index Test (All tests)
If a threshold was used, was it pre‐specified?	Yes
Were imaging test's quality assessed?	Yes
Were any conflict of interest avoided	Unclear
Could the conduct or interpretation of the index test have introduced bias?		Unclear risk
Are there concerns that the index test, its conduct, or interpretation differ from the review question?			Low concern
DOMAIN 3: Reference Standard
Is the reference standards likely to correctly classify the target condition?	Yes
Were the reference standard results interpreted without knowledge of the results of the index tests?	Unclear
Could the reference standard, its conduct, or its interpretation have introduced bias?		Low risk
Are there concerns that the target condition as defined by the reference standard does not match the question?			Low concern
DOMAIN 4: Flow and Timing
Was there an appropriate interval between index test and reference standard?	No
Did all patients receive the same reference standard?	Yes
Were all patients included in the analysis?	No
Did all patients receive a reference standard	Yes
Could the patient flow have introduced bias?		High risk