We have conducted a three pillars (questionnaire-based, physical, and laboratory investigations) cross-sectional study in the Hungarian general and Roma populations in 2018 in North-East Hungary on samples of randomly selected adults aged 20–64 years. We defined uncorrected visual acuity and the use of glasses and/or contact lenses as well as the effect of demographic, socioeconomic and health parameters on the visual acuity. The only data available on the visual function of Roma came from Spain and showed that this population was more likely to present with vision limitations and showed a lower use of corrective aids than the general population. Contrary to this study, we found that the Hungarian Roma population has a slightly, but significantly better average uncorrected visual acuity in every age and sex groups as compared to the Hungarian general population. However, this difference did not translate into a clinically significant difference, as the proportion of people with a visual acuity below 0.5 did not significantly differ in the two populations. It is noteworthy, that educational level was significantly lower in the Roma population in all age groups which could have a great role in their socioeconomic segregation and lower social opportunities. However, association between more years spent in education and myopia as suggested by a previous study31 could not be confirmed in the present study as educational level had no statistically significant effect on the visual acuity. We cannot exclude the possibility that refractive parameters in the Roma population are closer to the normal emmetropy which could be a genetically determined characteristic32,33. Cultural and social isolation, as well as high level of genetic consanguinity throughout the centuries has led to a certain genetic segregation of Roma populations34–36. This is not only characterized by an overload of founder mutations, but also by the lack or decreased frequency of some other pathogenic mutations in these populations. These factors lead to a decreased genetic diversity in the Roma population, but the frequency of rare genetic variants and pathogenic alleles maybe both higher37–39 and lower16,40 as compared with the general population.
One of the strongest differences between the two populations was found in the use of vision correcting aids. The use of simple visual aids for distance vision, such as glasses or contact lenses, was significantly lower in members of the Hungarian Roma population. This difference was confirmed in all age and both sex groups. This difference could not be explained through the somewhat better visual acuity measured in the Roma population, because the proportion of eyes with a visual acuity below 0.5 did not significantly differ in the two groups. It is noteworthy, that the largest difference in wearing a vision correction aid was found in the group with a visual acuity below 0.5 with one or both eyes, indicating a serious unmet health need in the Hungarian Roma population. The lack of a proper visual correction in the Roma population may severely contribute to their lower education level, lower social opportunities and lower access to the labor market and finally to their social segregation.
We examined the association of demographic and certain health parameters with the visual acuity. Age, abdominal obesity and elevated fasting glucose level and/or anti-diabetic treatment had a statistically significant negative effect on the visual acuity as a continuous variable. However, when visual acuity was analysed as a binary covariate and decreased visual acuity was defined as vision on both eyes less than 0.5, the only statistically significant association was found with the elevated fasting glucose level and/or anti-diabetic treatment in both populations. Elevated fasting glucose and/or anti-diabetic treatment was a stronger risk factor among the Roma population than in the Hungarian general population. This is in line with our previous findings indicating that elevated plasma glucose or known type 2 diabetes are significantly more frequent in the Hungarian Roma than in the Hungarian general population and that the proportion of untreated diabetes is very high (53.3%) in the Roma population41,42. Also the proportion of missed glucose check-ups was significantly higher in the Roma than in de Hungarian population43. It is worth mentioning that in a comparative analysis the Hungarian general population carried a greater genetic risk for the development of type 2 diabetes mellitus than Roma, but in a combined population model the effect of ethnicity was relatively strong on the development of diabetes (OR: 2.484, p<0.001)44.
The prevalence of metabolic syndrome (HG: 39.8%, HR: 44.0%) and insulin resistance (HG: 42.3% and HR: 40.5%) was - almost equally - very unfavourable in both populations28. In our present study there was a trend for people with higher waist circumference to have lower visual acuity as seen in the linear regression analysis using vision acuity as a continuous variable. However, this association could not be verified when using a clinically significant cut–off value (UCVA lower than 0.5) and vision was considered as a binary variable. On the other hand, based on the present study one cannot exclude the influence of central obesity on visual acuity in these populations. This should be further investigated, not only because very little is known about this association, but also because the prevalence of abdominal obesity is strongly increasing in the Hungarian Roma population42.
In the Roma population female sex was shown to be an independent risk factor for lower visual acuity, however this should be taken into consideration with precaution as the female sex was overrepresented in the Roma sample and this can be seen as a limitation of the study. This cross-sectional survey was based on randomly selected households, and as we described previously in many households, a proportionally higher number of women were at home during the day when most visits took place, and men at work at another location28. The Hungarian government quadrupled the budget for public works between 2010 and 2015 for all Hungarian municipalities. This is especially relevant for villages in the North-eastern region of Hungary, where segregated Roma settlements are concentrated and our study was carried out. The majority of workers participating in the programme are men from deprived Roma communities.
Our results suggest a slightly better average uncorrected visual acuity in the Hungarian Roma population but a much lower use of vision aids as well as a stronger negative effect of diabetes on uncorrected visual acuity in comparison with the Hungarian general population. These results call for public health actions for the improvement of poor primary care indicators on regular eye examination45, and a much more rigorous diabetes control within the Roma population43 in Hungary. These measures could have an important impact on the social integration of Roma people in the Hungarian society.