Table 3 Baseline characteristics of the respondents
|  | Grade 1 (n = 80) | Grade 2 (n = 80) | Grade 3 (n = 84) | Grade 4 (n = 90) | Total (n = 334) | P |
|---|---|---|---|---|---|---|
Sex | ||||||
 Male | 36(45%) | 37((46%) | 39(46%) | 39(43%) | 151(45%) | 0.975 |
 Female | 44(55%) | 43(54%) | 45(54%) | 51(57%) | 183(55%) |  |
Age | ||||||
 60 ~ 70 | 45(56%) | 51(64%) | 47(56%) | 57(63%) | 200(60%) | 0.83 |
 71 ~ 80 | 26(33%) | 21(26%) | 30(36%) | 26(29%) | 103(31%) |  |
 81 ~ 90 | 9(11%) | 8(10%) | 7(8%) | 7(8%) | 31(9%) |  |
Education Level | ||||||
 Primary and below | 20(25%) | 20(25%) | 20(24%) | 23(26%) | 83(25%) | 0.659 |
 Junior high school | 39(49%) | 36(45%) | 44(52%) | 51(57%) | 170(51%) |  |
 Senior high school | 8(10%) | 18(23%) | 11(13%) | 10(11%) | 47(14%) |  |
 University and above | 13(16%) | 6(7%) | 9(11%) | 6(7%) | 34(10%) |  |
Current residence | ||||||
 City | 60(75%) | 64(80%) | 67(80%) | 70(78%) | 261(78%) | 0.859 |
 Country | 20(25%) | 16(20%) | 17(20%) | 20(22%) | 73(22%) |  |
Medical Insurance | ||||||
 with | 76(95%) | 78(97%) | 80(95%) | 85(94%) | 319(96%) | 0.792 |
 without | 4(5%) | 2(3%) | 4(5%) | 5(6%) | 15(4%) |  |
Diagnosis | ||||||
 Cataract | 52(65%) | 54(68%) | 56(67%) | 73(81%) | 235(70%) | 0.23 |
 Glaucoma | 20(24%) | 13(16%) | 13(15%) | 9(10%) | 55(16%) |  |
 Diabetic retinopathy | 10(13%) | 16(20%) | 19(21%) | 21(23%) | 66(20%) |  |
 Macular degeneration | 8(10%) | 10(13%) | 12(14%) | 8(9%) | 38(11%) |  |
 Others | 10(13%) | 11(14%) | 17(20%) | 14(16%) | 52(16%) |  |
Duration of Illness | ||||||
  < 1 year | 43(54%) | 46(58%) | 39(46%) | 51(57%) | 179(54%) | 0.879 |
 1–5 years | 29(36%) | 27(34%) | 34(40%) | 29(32%) | 119(36%) |  |
 5–10 years | 5(6%) | 4(5%) | 5(6%) | 7(8%) | 21(6%) |  |
  > 10 years | 3(4%) | 3(4%) | 6(7%) | 3(3%) | 15(4%) |  |
Other Chronic Disease | ||||||
 None | 31(39%) | 19(24%) | 41(49%) | 30(33%) | 121(36%) | 0.279 |
 Diabetes | 37(46%) | 46(58%) | 25(30%) | 39(43%) | 147(44%) | |
 Hypertension | 25(31%) | 34(42%) | 24(29%) | 43(48%) | 126(38%) | |
 Others | 7(9%) | 5(6%) | 2(2%) | 4(4%) | 18(5%) | |