Table 4

 Changes of visual acuity (the proportion of VA worse than two lines) during follow up period

Age (years)M1M2M3M4M5
40–490/46 (0%)1/138 (0.7%)3/12 (25%)1/2 (50%)1/1 (100%)
50–590 (0%)4/79 (5.1%)15/32 (46.9%)9/15 (60%)6/9 (66.7%)
60–690 (0%)3/38 (7.9%)22/37 (59.5%)15/19 (78.9%)11/14 (78.6%)
⩾700 (0%)4/21 (19.0%)28/47 (59.6%)25/32 (78.1%)8/10 (80%)
Total0/46 (0%)12/276 (4.3%)68/128 (53.1%)50/68 (73.5%)26/34 (76.5%)