[1] Univ London London Sch Hyg & Trop Med, Dept Epidemiol & Populat Sci, London WC1E 7HT, England
[2] Erasmus Med Ctr, Dept Ophthalmol, Rotterdam, Netherlands
[3] Erasmus Med Ctr, Dept Epidemiol & Biostat, Rotterdam, Netherlands
[4] Univ Amsterdam, Acad Med Ctr, Dept Ophthalmol, Netherlands Ophthalm Res Inst,KNAW, NL-1105 AZ Amsterdam, Netherlands
[5] Queens Univ Belfast, Dept Ophthalmol, Belfast BT7 1NN, Antrim, North Ireland
[6] Queens Univ Belfast, Ctr Clin & Populat Sci, Belfast BT7 1NN, Antrim, North Ireland
[7] Univ Bergen, Haukeland Sykehus, Oyeavdelingen, N-5020 Bergen, Norway
[8] Univ De Creteil, Clin Ophtalmol, Paris, France
[9] Univ Verona, Clin Oculist, I-37100 Verona, Italy
[10] Aristotle Univ Thessaloniki, Sch Med, Dept Ophthalmol B, GR-54006 Thessaloniki, Greece
[11] Univ E Anglia, Ctr Environm Risk, Norwich NR4 7TJ, Norfolk, England
[12] Natl Inst Hlth Dev, Dept Epidemiol & Biostat, Tallinn, Estonia
[13] Univ Miguel Hernandez, Dept Salud Publ, Alicante, Spain