Introduction
Background
Rationales and objectives
Methods
Ethics approval and informed consent
Study area and sampling
Measurements
Operational definitions
Data analysis
Results
Characteristics of subjects
Descriptive and univariate logistic analysis
Multivariate logistic analysis
Variables | Unilateral Visual Impairment | Bilateral Visual Impairment | |||
---|---|---|---|---|---|
AOR (95% CI) | p-value | AOR (95% CI) | p-value | ||
Age (Years) | 1.04 (1.00–1.09) | 0.031** | 1.08 (1.02–1.15) | 0.011** | |
Educational level: | |||||
Primary level or below (ref) | 1.00 | – | |||
Secondary level | 0.54 (0.26–1.13) | 0.103 | |||
Non-degree level | 0.28 (0.09–0.80) | 0.022** | |||
Degree level | 0.29 (0.08–0.89) | 0.039** | |||
Housing type: | |||||
Private housing (ref) | 1.00 | – | |||
Temporary housing | 8.26 (1.81–34.92) | 0.004*** | |||
Obesity (BMI ≥ 25) | |||||
No (Ref) | 1.00 | – | 1.00 | – | |
Yes | 1.86 (0.99–3.51) | 0.053* | 4.00 (1.49–11.41) | 0.007 | *** |
Hyperlipidemia | |||||
No (Ref) | 1.00 | – | |||
Yes | 3.60 (1.13–10.97) | 0.025** | |||
Glaucoma | |||||
No (Ref) | 1.00 | – | |||
Yes | 4.11 (0.69–32.92) | 0.132 |
Confounding, effect modification and stratified analysis
Unilateral Visual Impairment | Bilateral Visual Impairment | |||
---|---|---|---|---|
Estimate (95% CI) | p-value | Estimate (95% CI) | p-value | |
A | ||||
Association of age with VI | 1.06 (1.02–1.10) | 0.001*** | 1.09 (1.03–1.15) | 0.003*** |
Association of age with obesity | 1.03 (0.99–1.06) | 0.163 | 1.03 (0.99–1.06) | 0.163 |
Association of obesity with VI | 2.00 (1.09–3.63) | 0.024** | 3.63 (1.46–9.36) | 0.006*** |
Association of age and obesity with VI | ||||
-Age | 1.06 (1.02–1.10) | 0.002*** | 1.09 (1.03–1.16) | 0.003*** |
-Obesity | 1.89 (1.02–3.49) | 0.041** | 3.58 (1.40–9.52) | 0.008*** |
Magnitude of confounding: relative change in OR of obesity on VI after adjusting the age | ||||
- Obesity | 5.50% | (< 10%) | 1.38% | (< 10%) |
B | ||||
Association of age with VI | 1.06 (1.02–1.10) | 0.001*** | 1.09 (1.03–1.15) | 0.003*** |
Association of age with history of hypertension | 1.10 (1.06–1.14) | < 0.001*** | 1.10 (1.06–1.14) | < 0.001*** |
Association of history of hypertension with VI | 1.97 (1.12–3.51) | 0.019** | 2.19 (0.89–5.61) | 0.091* |
Association of age and history of hypertension with VI | ||||
-Age | 1.05 (1.01–1.09) | 0.002*** | 1.08 (1.02–1.15) | 0.008*** |
-History of hypertension | 1.52 (0.83–2.79) | 0.008** | 1.48 (0.56–3.95) | 0.426 |
Magnitude of confounding: relative change in OR of history of hypertension on VI after adjusting the age | ||||
- History of hypertension | 22.84% | (> 10%) | 32.42% | (> 10%) |
C | ||||
Association of age with VI | 1.06 (1.02–1.10) | 0.001*** | 1.09 (1.03–1.15) | 0.003*** |
Association of age with history of hyperlipidemia | 1.04 (0.99–1.08) | 0.121 | 1.04 (0.99–1.08) | 0.121 |
Association of history of hyperlipidemia with VI | 1.53 (0.71–3.22) | 0.266 | 3.22 (1.13–8.51) | 0.021** |
Association of age and history of hyperlipidemia with VI | ||||
-Age | 1.06 (1.02–1.10) | 0.002*** | 1.09 (1.03–1.16) | 0.004*** |
-History of hyperlipidemia | 1.37 (0.63–2.93) | 0.419 | 2.96 (1.01–8.06) | 0.038** |
Magnitude of confounding: relative change in OR of history of hyperlipidemia on VI after adjusting the age | ||||
- History of hyperlipidemia | 10.46% | (≈ 10%) | 8.07% | (< 10%) |
D | ||||
Association of age with VI | 1.06 (1.02–1.10) | 0.001*** | 1.09 (1.03–1.15) | 0.003*** |
Association of age with educational level | 0.91 (0.88–0.95) | < 0.001*** | 0.91 (0.88–0.95) | < 0.001*** |
Association of educational level with VI | ||||
- Secondary level | 0.44 (0.22–0.88) | 0.020** | 0.19 (0.06–0.53) | 0.002*** |
- Non-degree level | 0.20 (0.07–0.56) | 0.003*** | 0.22 (0.03–0.89) | 0.058* |
- Degree level | 0.21 (0.06–0.61) | 0.006*** | 0.27 (0.04–1.11) | 0.106 |
Association of age and educational level with VI | ||||
-Age | 1.05 (1.01–1.09) | 0.018** | 1.07 (1.01–1.14) | 0.030** |
-Educational level | ||||
- Secondary level | 0.55 (0.27–1.13) | 0.101 | 0.25 (0.08–0.74) | 0.014** |
- Non-degree level | 0.26 (0.08–0.72) | 0.013** | 0.32 (0.05–1.40) | 0.169 |
- Degree level | 0.29 (0.08–0.86) | 0.034** | 0.44 (0.06–2.02) | 0.333 |
Magnitude of confounding: relative change in OR of educational level on VI after adjusting the age | ||||
- Secondary level | 25% | (> 10%) | 31.58% | (> 10%) |
- Non-degree level | 30% | (> 10%) | 45.45% | (> 10%) |
- Degree level | 38% | (> 10%) | 62.96% | (> 10%) |
Unilateral VI | Bilateral VI | |||
---|---|---|---|---|
Est. (95% CI) | p-value | Est. (95% CI) | p-value | |
Model A | ||||
History of hyperlipidemia | 0.00 (0.00–18.45) | 0.245 | 0.01 (0.00–304.4) | 0.413 |
Age | 1.05 (1.01–1.09) | 0.012** | 1.07 (1.00–1.14) | 0.037** |
History of hyperlipidemia: Age | 1.09 (0.96–1.26) | 0.217 | 1.08 (0.94–1.28) | 0.308 |
Model B | ||||
History of hyperlipidemia | 3.55 (1.25–10.51) | 0.019** | 5.82 (1.54–23.11) | 0.009*** |
Gender | 1.29 (0.68–2.51) | 0.444 | 1.02 (0.34–3.45) | 0.971 |
History of hyperlipidemia: Gender | 0.14 (0.02–0.71) | 0.023** | 0.15 (0.01–1.45) | 0.142 |
Model C | ||||
History of hyperlipidemia | 0.52 (0.14–1.51) | 0.266 | 1.81 (0.26–8.16) | 0.477 |
Obesity | 1.28 (0.65–2.48) | 0.476 | 2.70 (0.88–8.30) | 0.077* |
History of hyperlipidemia: Obesity | 17.64 (2.82–164.9) | 0.005*** | 2.64 (0.33–27.57) | 0.376 |
Model D | ||||
History of hyperlipidemia | 0.80 (0.17–2.81) | 0.746 | 1.18 (0.06–7.26) | 0.883 |
History of hypertension | 1.69 (0.90–3.19) | 0.104 | 1.39 (0.44–4.18) | 0.559 |
History of hyperlipidemia: History of hypertension | 2.17 (0.43–13.14) | 0.365 | 3.45 (0.36–81.31) | 0.332 |
Model E | ||||
History of hyperlipidemia | 1.02 (0.39–2.46) | 0.965 | 2.75 (0.70–9.26) | 0.116 |
History of cataract | 1.23 (0.59–2.50) | 0.574 | 1.99 (0.58–6.12) | 0.242 |
History of hyperlipidemia: History of cataract | 5.49 (0.87–48.40) | 0.086* | 1.66 (0.19–14.45) | 0.640 |
Unilateral Visual Impairment | Bilateral Visual Impairment | Unilateral Visual Impairment | Bilateral Visual Impairment | ||||||
---|---|---|---|---|---|---|---|---|---|
Estimate (95% CI) | p-value | Estimate (95% CI) | p-value | Estimate (95% CI) | p-value | Estimate (95% CI) | p-value | ||
A | Stratified by gender | Male | Female | ||||||
i | Obesity | 1.53 (0.61–3.81) | 0.359 | 5.78 (1.52–28.18) | 0.015** | 2.44 (1.09–5.48) | 0.030** | 2.11 (0.51–7.89) | 0.271 |
ii | History of hypertension | 2.21 (0.90–5.62) | 0.087* | 2.96 (0.79–14.32) | 0.129 | 1.83 (0.85–3.90) | 0.118 | 1.42 (0.35–5.24) | 0.605 |
iii | History of hyperlipidemia | 3.55 (1.25–10.51) | 0.019** | 5.82 (1.54–23.11) | 0.009*** | 0.50 (0.11–1.68) | 0.304 | 0.88 (0.05–5.23) | 0.908 |
iv | History of cataract | 2.29 (0.79–6.68) | 0.125 | 4.04 (1.03–15.49) | 0.040** | 1.31 (0.56–2.96) | 0.523 | 1.36 (0.28–5.22) | 0.672 |
B | Stratified by obesity | Obesity | Non-obesity | ||||||
i | Gender | 1.30 (0.49–3.48) | 0.599 | 0.40 (0.10–1.43) | 0.172 | 0.82 (0.40–1.70) | 0.580 | 1.09 (0.28–5.35) | 0.901 |
ii | History of hypertension | 1.12 (0.41–3.06) | 0.830 | 2.23 (0.59–10.87) | 0.267 | 2.18 (1.04–4.53) | 0.037** | 1.13 (0.23–4.50) | 0.864 |
iii | History of hyperlipidemia | 9.21 (2.15–64.10) | 0.007*** | 4.80 (1.16–19.81) | 0.028** | 0.52 (0.14–1.51) | 0.266 | 1.81 (0.26–8.16) | 0.477 |
iv | History of cataract | 1.64 (0.48–5.76) | 0.424 | 1.47 (0.29–6.02) | 0.611 | 1.71 (0.77–3.71) | 0.176 | 4.32 (1.08–18.33) | 0.037** |
C | Stratified by history of hypertension | Having a history | No history | ||||||
i | Gender | 0.91 (0.39–2.13) | 0.829 | 0.45 (0.11–1.56) | 0.222 | 1.10 (0.49–2.59) | 0.818 | 0.94 (0.24–4.64) | 0.934 |
ii | Obesity | 1.25 (0.53–2.94) | 0.608 | 4.35 (1.19–20.82) | 0.037** | 2.43 (0.98–5.97) | 0.052* | 2.22 (0.44–9.08) | 0.284 |
iii | History of hyperlipidemia | 1.73 (0.64–4.73) | 0.274 | 4.07 (1.13–14.82) | 0.030** | 0.80 (0.17–2.81) | 0.746 | 1.18 (0.06–7.26) | 0.883 |
iv | History of cataract | 1.99 (0.81–5.02) | 0.137 | 2.45 (0.70–8.67) | 0.154 | 0.95 (0.32–2.54) | 0.926 | 1.41 (0.20–6.36) | 0.678 |
D | Stratified by history of hyperlipidemia | Having a history | No history | ||||||
i | Gender | 0.18 (0.03–0.79) | 0.032** | 0.15 (0.01–1.08) | 0.104 | 1.29 (0.68–2.51) | 0.444 | 1.02 (0.34–3.45) | 0.971 |
ii | Obesity | 22.50 (4.11–192.5) | 0.001*** | 7.14 (1.24–58.63) | 0.038** | 1.28 (0.65–2.48) | 0.476 | 2.70 (0.88–8.30) | 0.077* |
iii | History of hypertension | 3.67 (0.84–20.04) | 0.100 | 4.80 (0.69–97.27) | 0.172 | 1.69 (0.90–3.19) | 0.104 | 1.39 (0.44–4.18) | 0.559 |
iv | History of cataract | 6.75 (1.25–53.54) | 0.038** | 3.30 (0.52–20.41) | 0.190 | 1.23 (0.59–2.50) | 0.574 | 1.99 (0.58–6.12) | 0.242 |
E | Stratified by cataract | Having a history | No history | ||||||
i | Gender | 0.57 (0.18–1.84) | 0.346 | 0.26 (0.05–1.22) | 0.093* | 1.00 (0.52–1.95) | 0.995 | 0.77 (0.25–2.50) | 0.658 |
ii | Obesity | 2.00 (0.56–7.40) | 0.286 | 1.98 (0.36–9.62) | 0.402 | 2.08 (1.05–4.14) | 0.036** | 5.83 (1.80–22.42) | 0.005*** |
iii | History of hypertension | 3.27 (1.03–11.40) | 0.051* | 2.86 (0.58–21.07) | 0.227 | 1.56 (0.79–3.06) | 0.192 | 1.65 (0.51–5.21) | 0.388 |
iv | History of hyperlipidemia | 5.60 (1.13–41.57) | 0.049** | 4.56 (0.76–25.60) | 0.082* | 1.02 (0.39–2.46) | 0.965 | 2.75 (0.70–9.26) | 0.116 |
Eye-level analysis
Descriptive statistics | Generalized linear mixed models | |||
---|---|---|---|---|
Eye examination results | Associations of VI with eye examination results | |||
Right eye | Left eye | Estimate (95% CI) | p-value | |
(n = 222) | (n = 222) | |||
Myopia or hyperopia | ||||
No (Ref) | 48 (21.62) | 56 (25.23) | 1.00 | – |
Yes | 174 (78.38) | 166 (74.77) | 6.69 (2.07–21.60) | 0.001*** |
Optic disc | ||||
Normal cases (ref) | 192 (86.49) | 196 (88.29) | 1.00 | – |
Abnormal or suspicious cases | 30 (13.51) | 26 (11.71) | 0.81 (0.29–2.29) | 0.697 |
Macula | ||||
Normal cases (ref) | 203 (91.44) | 202 (81.98) | 1.00 | – |
Abnormal or undetermined cases | 19 (8.56) | 20 (9.01) | 3.02 (0.92–9.94) | 0.069* |