Table 1

Characteristics of the included studies

Study IDSample size (patients/eyes)Mean age/ range (years)Mean duration of diabetes/range (years)Digital imaging techniqueImage resolution (pixels)Compression rate
Bursell et al3354/10848/20–7517.7/3.0–423-field, 45°, stereoscopic, colour, non-mydriatic640×48010:1
Fransen et al29290/549ND/>18Any duration7-field, 30°, stereoscopic, colour, mydriatic1152×1152
Lin et al16197/-ND/>21Any duration1-field, 45°, monoscopic, monochromatic, non-mydriatic640×480
Massin et al3574/14752/25–748/0–235-field, 45°, non-stereoscopic, colour, non-mydriatic800×600
Boucher et al2798/19659.9/26–92ND2-field, 45°, stereoscopic, colour, non-mydriatic600×800
Hansen et al2083/16547/25–7022/1–535-field, 45°, non-stereoscopic, colour, mydriatic1450×1026
59/11847/25–7022/1–535-field, 45°, non-stereoscopic, colour, non-mydriatic1450×1026
Schiffman et al30111/22257/18–9919/1–4915-field, 55–60°, non-stereoscopic, monochromatic, mydriaticND
Rudnisky et al19102/204ND/23–92ND/1 months- 35 years7-field, 30°, stereoscopic (fields 1 and 2) and non-stereoscopic (fields 3 to fields 7), colour, mydriatic3040×200816:1
Li et al2385/15259.4/33–83ND7-field, 35°, stereoscopic, colour, mydriatic2392×2048
Li et al2285/15259.4/33–83ND7-field, 35°, monoscopic, colour, mydriatic2400×2000
Li et al2485/15259.4/33–83ND7-field, 35°, stereoscopic, colour, mydriatic2400×200037:1
Li et al2185/15259.4/33–83ND7-field, 35°, stereoscopic, colour, mydriatic2400×2000
7-field, 35°, stereoscopic, colour, mydriatic2400×200037:1
7-field, 35°, monoscopic, colour, mydriatic2400×2000
9-field, 45°, monoscopic, MosD (mosaic digital), colour, mydriatic3000×2000
Li et al2585/15259.4/33–83ND9-field, 45°, monoscopic, MosD, colour, mydriatic3000×2000
Gangaputra et al3696/15762/37–8619/ND7-field, 30°, stereoscopic or 4-field 45–60° stereoscopic, colour, mydriatic*ND
Hubbard et al15319/62848/ND27.2/ND7-field, 30°, stereoscopic, colour, mydriaticND20:1
Kernt et al1734/6662/ND14.2/>31-field, 200°, non-stereoscopic, colour, non-mydriaticND
Maker et al26106/21149/19–7823.7/1–667-field, 30°, stereoscopic, colour, mydriatic1280×1024
Silva et al3167/12649/24–8321.1/1–513 separate stereoscopic 45° fields, 2 30° stereoscopic fields, and an external image, colour, non-mydriatic1000×1000
Silva et al32103/20653.9/18–88ND1-field, 100° and 200°, stereoscopic, colour, non-mydriatic1200×1600
Kernt et al18141/21264/25–7812/3–391-field, 180–200°, non-stereoscopic, colour, non-mydriatic3900×3072
  • *48 (31%) digital images were obtained at a 45–60° angle and 109 (69%) with the common 30° angle.

  • †There were three comparable groups in the three studies: two of these groups were identical. One used the reference standard 7F-ETDRS; the other involved 7-field 35° stereoscopic colour images with mydriasis. The third comparable group differed from those in the three studies and is presented in the table.

  • ETDRS, Early Treatment Diabetic Retinopathy Study; ND, no data available.