Table 4

 Main anatomical site of abnormality, and underlying aetiology in 1935 severely visually impaired and blind children, by age of onset of disorder

CongenitalInfantile*⩾1 to <5 years⩾5 to <16 years
n (%)n (%)n (%)n (%)
*Postnatal to <1 year.
†χ2, showing significant differences in anatomical, aetiological and type of blindness by age of onset of disorder.
‡Includes children that had either no anatomical abnormality (n = 14) or no anterior segment abnormality, but the posterior segment was not examined (n = 5) because the child was too young and/or uncooperative and/or had multiple disabilities.
§Perinatal, intrauterine.
Anatomical p<0.001†
    Whole globe199 (78.7)14 (5.5)26 (10.3)14(5.5)
    Cornea38 (7.4)82 (16.0)281 (54.7)113 (22.0)
    Lens189 (30.1)230 (36.6)152 (24.2)58 (9.2)
    Uvea15 (39.5)2 (5.3)5 (13.2)16 (42.1)
    Retina105 (42.9)39 (15.9)59 (24.1)42 (17.1)
    Optic nerve23 (14.9)25 (16.2)51 (33.1)55 (35.7)
    Glaucoma37 (44.6)19 (22.9)14 (16.9)13 (15.7)
    Other‡6 (31.6)3 (15.8)4 (21.1)6 (31.6)
Aetiology p<0.001†
    Hereditary156 (53.6)52 (17.9)55 (18.9)28 (9.6)
    Childhood factor20 (3.4)103 (17.4)319 (53.8)151 (25.5)
    Other§12 (70.6)2 (11.8)2 (11.8)1 (5.9)
    Unknown424 (41.0)257 (24.9)216 (20.9)137 (13.3)
Type of blindness p<0.001†
    Preventable14 (2.6)84 (15.6)305 (56.8)134 (25.0)
    Treatable246 (30.7)259 (32.3)183 (22.9)113 (14.1)
    Unavoidable352 (59.0)71 (11.9)104 (17.4)70 (11.7)
    Total612 (31.6)414 (21.4)592 (30.6)317 (16.4)