Monocular blindness in Bayelsa state of Nigeria.

Background: Monocular blindness has not received much attention in developing countries despite its numerous disadvantages. A monocularly blind person is at high risk of being bilaterally blind. The objective of this study was to determine the causes of monocular blindness in the study population and to suggest strategies for prevention.

Methods: A prospective study was conducted among new consecutive patients that presented to our clinic over a period of one year and those with visual acuity (VA) less than 3/60 in the worse eye after optical correction or with pin hole as necessary were studied. Visual acuity was determined using a snellen acuity chart, followed by a full ocular examination including anterior and posterior segment examination. Objective refraction was carried out followed by a subjective refraction. Other information obtained from the patients included their age, sex and occupation. All collected data was documented in a questionnaire designed for this study. Data were recorded and analysed using a scientific calculator.

Results: Over a one year period, 149 patients presented with monocular blindness. There were 92 males and 57 females (Male to female ratio of 1.6).Their ages ranged from 3 to 84 years (mean age of 44.4 years). The majority of the patients were public servants and students constituting 28.8% and 20.1 % or patients respectively. The two leading causes of monocular blindness were cataract and uveitis constituting 41.5% and 12.7% of monocular blindness respectively. Other causes in decreasing order includes glaucoma(10.7%), cornea diseases(8.7%), trauma(8.0%), phtisis bulbi (5.4%), aphakia (4.0%), maculopathy (3.4%), optic atrophy (2.7%), ophthalmitis (1.3%), retinitis pigmentosa and retinal detachment (each 0.7%). The majority of the blindness (96.4 %) was avoidable.

Conclusion: Cataract was the leading cause of monocular blindness. Uveitis was found to be an important cause of monocular blindness in this population. While efforts need to be made to increase the uptake of cataract surgery in this population, the aetiology and risk factors of uveitis need to be explored. Overall, more emphasis should be placed on health education as the majority of monocular blindness in this population is avoidable.