ABSTRACT
This study was carried out to determine the distribution of refractive errors in different blood groups amongst students of the University of Benin, Benin City, Edo State, Nigeria. A total of sixty (n = 60) participants, males and females within the age range of 18–28 years (mean age = 19.83 ± 2.159), were used for this study. A convenience sampling technique was used. The case history included ocular, medical, family, and drug histories. Visual acuity was assessed with Snellen's chart and near-point card, and eye examinations ruled out ocular abnormalities and other causes of visual impairment. Refractive states were determined through objective and subjective refraction. Blood samples were collected and separated into red blood cells and plasma by centrifugation, and blood types were determined through agglutination reactions using A, B, and Rh antibodies. The result of this study showed that blood group O had 43 (71.7%) participants, with blood group AB having the least participants, 2 (3.3%). In blood group O, astigmatism was the most common, with 16 (37.2%) respondents, with myopia having the fewest, 6 (14.0%). In blood group AB, all participants had astigmatism, 2 (100%). In the rhesus blood grouping system, rhesus positive (+) participants were 52 (86.7%), with astigmatism having the highest participants, 13 (46.1%) in this group. Chi-square test was carried out to determine if there was a significant association between variables. Statistically, there was no significant association between refractive errors and ABO blood groups (P = 0.794, p > 0.05), but a significant association was found with the Rhesus blood group system (P = 0.019, p < 0.05). It was concluded from the study that blood group O had the highest number of participants, followed by blood groups A and B, while blood group AB had the fewest respondents. Rhesus-positive individuals had more refractive errors compared to Rhesus-negative individuals. Astigmatism was the most common refractive error in all blood groups, followed by hyperopia, with myopia being the least common.
