# Impact of Urbanization and Sunlight Exposure on Cataract Incidence
## 4 Discussion  
The results of our study reveal that urbanization is a critical factor for the incidence of senile cataracts. The highest and second highest urbanized areas (\"highly urbanized\" and \"high urbanized\" areas) have 1.41 times and 1.22 times higher risk of developing senile cataracts than those living in remote areas. Nonetheless, the association between urbanization and the incidence of senile cataracts is not significant for those who live in medium and low urbanized areas. Our study result is similar to a study examining the prevalence of cataracts in Taiwan between 2001 and 2013 and concluded that those living in highly urbanized areas were \begin{table}
\begin{tabular}{l c c c} \hline \hline
**Variables** & **Parameters** & **Odds Ratio (OR)** & _p-Value_ \\ \hline Urbanization (Ref: Remote areas) & & & \\ Highly urbanized & 0.35 & 1.41 & \(<\)0.001 *** \\ High urbanized & 0.20 & 1.22 & \(<\)0.01 ** \\ Medium urbanized & \(-\)0.07 & 0.94 & 0.36 \\ Low urbanized & \(-\)0.05 & 0.95 & 0.42 \\ \hline \hline \end{tabular}  
* \(p\) \(<\) 0.01, *** \(p\) \(<\) 0.001.  
\end{table} 
Table 4: Urbanization and Incidence of Cataract (N = 396,321). \begin{table}
\begin{tabular}{l c c c} \hline \hline
**Variables** & **DF** & **Parameter** & **SD** & _p-Value_ \\ \hline Intercept & 1 & \(-\)8.15 & 0.17 & \(<\)0.001 *** \\ Urbanization (Ref: Remote areas) & & & \\ Highly urbanized & 1 & 0.35 & 0.07 & \(<\)0.001 *** \\ High urbanized & 1 & 0.20 & 0.07 & \(<\)0.01 ** \\ Medium urbanized & 1 & \(-\)0.07 & 0.07 & 0.36 \\ Low urbanized & 1 & \(-\)0.05 & 0.07 & 0.42 \\ Age (Ref: 40–49 Years) & & & \\
50–59 & 1 & 1.98 & 0.13 & \(<\)0.001 *** \\
60–69 & 1 & 3.53 & 0.12 & \(<\)0.001 *** \\
70–79 & 1 & 4.08 & 0.12 & \(<\)0.001 *** \\
80 and above & 1 & 3.82 & 0.13 & \(<\)0.001 *** \\ Gender (Ref: Females) & 1 & \(-\)0.15 & 0.04 & \(<\)0.001 *** \\ Occupation (Ref: Farmers) & & & & \\ School teachers/staff & 1 & \(-\)0.08 & 0.07 & 0.24 \\ Industry employees & 1 & 0.27 & 0.08 & \(<\)0.001 *** \\ Government employee & 1 & \(-\)0.06 & 0.16 & 0.77 \\ Self-employed & 1 & \(-\)6.29 & 265.9 & 0.98 \\ Vocational union staff & 1 & \(-\)0.19 & 0.08 & \(<\)0.01 ** \\ Foreign seamen & 1 & \(-\)6.70 & 120.1 & 0.96 \\ Fishermen/Seamen & 1 & 0.46 & 0.13 & \(<\)0.001 *** \\ Dependents-deceased public & 1 & 0.24 & 0.42 & 0.56 \\ servants & 1 & \(-\)0.10 & 0.21 & 0.64 \\ Low income & 1 & \(-\)0.36 & 0.32 & 0.26 \\ Veterans & 1 & 0.36 & 0.06 & \(<\)0.001 *** \\ Others (e.g., religious people, etc.) & 1 & 0.003 & 0.00 & \(<\)0.001 *** \\ Duration of Sunlight Exposure & 1 & 0.003 & 0.00 & \(<\)0.001 *** \\ Comorbidities & & & & \\ Diabetes & & & & \\ Chronic kidney disease & 1 & 0.98 & 0.14 & \(<\)0.001 *** \\ Chronic kidney disease & 1 & 2.55 & 1.00 & \(<\)0.005 * \\ Hypertension & 1 & 4.78 & 0.50 & \(<\)0.001 *** \\ \hline \hline \end{tabular}  
* \(p\) \(<\) 0.05, *** \(p\) \(<\) 0.01, *** \(p\) \(<\) 0.001.  
\end{table} 
Table 3: Results of Logistic Regression (N = 396,321). more likely to have cataracts than those living in other levels of urbanization [16]. Our finding is also similar to the result of a study from China [17]. However, two studies from India reported different results from our research, indicating either significantly higher cataract incidence in rural areas or no difference in cataract incidence between urban or rural areas [18; 19]. Although it seems that whether urbanization levels will impact the incidence of cataracts is still controversial, study results from Taiwan are consistent. They concluded that higher urbanization is a risk factor for senile cataracts. Therefore, it is valuable for academia to devote to more studies focusing on the impact of urbanization on the incidence of cataracts. Our study result is consistent with many previous studies regarding the association of sunlight exposure and the incidence of cataracts [13; 14; 15].