Gender has been associated with hyperopia. Although numerous studies found no statistically significant difference between the two sexes, some data show females have a significantly higher risk of hyperopia.
From the RESC protocol surveys, Nepal (27), Chile (28), India (31) and China (29) found hyperopia was associated with female gender. Studies on older individuals (15,21,22,35,36,48) also drew the same conclusion. In some cases females had almost twice the prevalence of males (15,21,36).
This finding may be related to the fact that women have shorter axial length than men (48). Mallen et al (16) found the average axial length in Jordanian males and females was 23.33mm and 22.99mm respectively. Considerable differences were also reported in children (49) and university students (25). As hyperopia is predominantly axial in nature, females appear to have a higher risk.
Conversely, hyperopia has been found to be more prevalent in males in a few studies (12,20,37). However, only one of these findings was statistically significant (37).
Whether hyperopia is more prevalent in an urban or a rural environment is inconclusive. It is thought there is a higher accommodative demand in urban areas, resulting in a push towards myopia. However, this is not always the case.
Both India and China had a considerably higher prevalence of hyperopia in the urban environment in the RESC surveys (29,30,31,33). Taking into account the same method and definition used…
In other parts of Asia, Bourne et al reported a higher prevalence of hyperopia in urban Bangladesh (23.0% vs 20.1%) (36). (Although not statistically significant, the rates of hyperopia were higher in Xiamen City and Singapore City (urban) than Xiamen countryside (rural) (10).)
Conversely, the APEDS (15) found a lower prevalence of hyperopia in rural areas. It is possible that this is related to less schooling in the rural area….
The Dezful Eye Study (13) found interesting results. Among primary and middle school students (7-15 yrs), hyperopia prevalence was significantly lower in participants from urban areas. However, the opposite was the case for high school students (14-18 yrs). A possible theory is that environmental factors may only have an influence during the emmetropization process.
On the whole, it seems that genetic influences are stronger than environmental influences for hyperopia (10). Location does not affect hyperopia to the same extent as myopia.
With increasing education the eye is subjected to increasing near work activity. This is thought to result in a push towards myopia ((15,18,26)). However, data showing educational attainment in studies is limited and inconclusive.
Wong et al (18) found a direct relationship between increasing education and decreasing hyperopia. Hyperopia significantly decreased from 50% in individuals with no education to 39.3%, 22.7% and 17.5% in individuals who had completed primary, secondary and tertiary education respectively.
The Baltimore Eye Study (21) reported the prevalence of hyperopia declined with increasing years of education although this relation was more pronounced in white adults than black adults.
The Beaver Dam Eye Study (17) found the mean refractive error became more negative with increasing education with a stronger relation among younger participants.
A study in Sumatra (47) also reported similar findings.
On the contrary, studies in India (15) and Bangladesh (36) found hyperopia was more common in subjects with any level of education than those who had never been to school, but this was insignificant.