Visual impairment, which includes low vision and blindness, remain a public health problem that has impact on socioeconomic values and quality of life of the community. This study was targeted to determine the magnitude and factors of visual impairment under the category of low vision and blindness so that stakeholders will have evidence to plan and implement prevention and management strategies in the hospital and surrounding communities.
In the present study the prevalence of visual impairment was 155 (17.6% (95% CI: 15.2, 20.1)). This finding is higher than other studies conducted within the communities [12, 15, 16]. This indicated that hospital burden of visual impairment is the reflective of community problems. It might also revealed that the patients comes to hospital is usually after their visual function is severely affected which is the common problems of low income population. It is lower than study conducted in South Africa (28.0%) and Ghana (28.2%) [17, 18]. The discrepancy observed here might be due to sampling technique in which they used non-probability sampling. The population difference and eye care service difference at the two centers might also contribute for the different proportion of visual impairment.
Among the study subjects, 91 (10.3% (95% CI: 8.2, 12.3)) had low vision and 64 (7.3 95%CI: 5.7, 9.0)) blindness. This finding indicated that the low vision and blindness is a major public health problem. In comparison to national survey result of low vision (3.7%) and blindness (1.6%) conducted 2005 in Ethiopia this finding is higher as it is hospital based unlike national survey [10]. Though 3 years left to the Vision to 2020 and ‘the right to sight’ goal, in this study area the burden of the low vision and blindness still high and need strengthening the prevention of avoidable causes of low vision and blindness. This result is consistent with similar study conducted in Gondar Ethiopia (15.3%) [19].
The prevalence of blindness in the study is lower than studies conducted in South Africa (10.9%) and Kenya (39.4%), higher than studies conducted in Cameroon (1.71%) but in line with study reported form Mali (5.8%) and Jordan (13.7%) [17, 20,21,22,23]. The low vision is consistent with study report from Nigeria (9.2%) and Cambodia (12%) [24, 25], but lower than South African study (16.3%) [17]. This reflects that there are a lot of factors that can contribute for geographical variations of low vision and blindness such as socio-economic difference, climatic change, gene and ethnical difference, health care service system, number of eye care givers and supportive organizations and not all of those could be investigated in the present study.
The amount of monocular low vision and blindness in this study was (13.2% (95% CI 10.9, 15.6)) and 170(19.3% (95% CI 17.0, 22.1)) respectively. As the worst visual acuity was considered to define monocular low vision and blindness, it is expected to be higher than bilateral one. This result is higher than study done in Thailand, which reported 3.0% low vision and 4.4% blindness [26]. The discrepancy observed here might be due to different socioeconomic values and eye care seeking behaviors.
The factors associated with low vision and blindness in the current study were age (<p < 0.001), cataract (p = 0.002), glaucoma (p = 0.002) and age related macular degeneration (p < 0.001). Age was reported from different clinical and community based studies as the main risk factors for visual impairment, low vision and blindness [27, 28]. However gender was not associated with low vision or blindness like study conducted in Australia [29]. The eye conditions such as cataract, glaucoma, and age related macular degeneration were also reported as the main etiology or causes of low vision and blindness [30]. Factors such as level of education, inability to afford service cost, fear of the outcome of the surgery especially for cataract and glaucoma and cultural beliefs are some of the reason why people remain low in vision and blindness. Those diseases are among either preventable or avoidable disease if they are diagnosed and treated early.
In addition to that uncorrected refractive error, ocular trauma and Pseudophakia were also among the major causes of low vision and blindness. These finding were also reported by different studies in Ethiopia from national survey and Gurage zone [11].
There was some limitation with this study. Most importantly different associated factors were not well explored, as it was hospital based and used secondary data from patients’ medical record.