Garudadri 2012.

Study characteristics
Patient Sampling	Prospective cross‐sectional study including normal participants and glaucoma patients evaluated between July 2003 and March 2005 at a tertiary eye care centre. One eye per person was randomly selected.
Patient characteristics and setting	Sample size: 220 eyes of 220 participants enrolled (125 glaucoma, 95 controls). Age: glaucoma eyes mean ± SD, 57.46 ± 9.65 years; controls 50.39 ± 10.76 years. Sex: 145 men (86 glaucoma, 59 controls) and 75 women (39 glaucoma, 36 controls). Ethnicity: Indian. Country: India. Setting: LV Prasad Eye Institute, Hyderabad. Ocular comorbidities: all eyes had to have BCVA ≥ 20/40, refractive error within ±5 D sphere and ±3 D cylinder of plano. Patients with intraocular surgery or laser within past 6 months, history or evidence of retinal or macular pathology, evidence of any systemic diseases or neurological disorders, which could produce a field defect were excluded. Spectrum of glaucoma severity: the mean ± SD MD on the VF test were ‐9.55 ± 8.61 dB for glaucoma. Control participants: IOP ≤ 22 mmHg, normal posterior segment evaluation and normal VF result.
Index tests	Scanning laser polarimetry: GDx VCC (software version 5.5.1; Carl Zeiss Meditec). Only properly‐focused and well‐centred images of the ONH with an image score ≥ 8 in both eyes were included in the study. Imaging was performed by 1 of 2 trained optometrists masked to the hypothesis and diagnosis. No conflict of interest with the device's manufacturer were reported by the authors.
Target condition and reference standard(s)	Manifest Glaucoma: glaucomatous ONH appearance (defined as focal or diffuse neuroretinal rim thinning, localised notching, or nerve fibre layer defects) and corresponding VF defects, defined as 2 of the following 3: the presence of a cluster of 3 points on pattern deviation probability plot with a P < 5%, one of which had a P < 1%, or a PSD with a P < 5%, or a GHT result outside normal limits. Visual field testing: Humphrey Field Analyzer (Carl Zeiss Meditec, Inc, Dublin, CA, USA) using the 30‐2 or 24‐2 SITa standard programme. Optic disc evaluation: indirect fundus ophthalmoscopy using a 78D or 90D lens.
Flow and timing	Index tests and reference standard were performed within 3 months. No patients were reported as excluded from the analysis by the authors.
Comparative
Notes	Garudadri CS was supported by Allergan and Merck, Parikh RS was supported by Merck, and Thomas R was supported by Allergan.
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	Yes
Could the conduct or interpretation of the index test have introduced bias?		Low 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?	Yes
Did all patients receive a reference standard	Yes
Could the patient flow have introduced bias?		High risk