Epidemiology of Glaucoma: A Population Study in the Akwapim South District of Ghana

Abstract

Modem Eye care in Ghana is making progress in prevention of blindness from cataract, onchocerciasis and trachoma, but stuck with glaucoma that remains the leading cause of permanent blindness in Ghana. This project addresses issues on the epidemiology of glaucoma by determining the magnitude of the burden of Primary Open Angle Glaucoma by a prevalence study in the Akwapim South district of Ghana. It looks at the factors related to advanced damaging effect on vision, socio-cultural and alternate eye care factors that influence eye care. A total of 1.843 people aged 30 years and above were screened in a crosssectional population survey. A prevalence of 6.6% with a 95% confidence interval of 5.46 to 7.76 and an exponential trend line for prevalence/age relationship was found in the 30-64year age group. A case- control study recruiting 123 patients with early features of glaucoma (control) and 93 patients with advanced glaucoma (cases) was also carried out for risk-factor analysis. Highest level of intra ocular pressure before treatment was the single most important factor associated with advanced visual loss and this was overwhelmingly significant. Adjusted Odd’s ratio of glaucoma by multiple logistic regression model showed that intraocular pressure> 31mmHg in a patient was nearly 3 times more likely to present with advanced glaucoma (OR 2.66, 95% confidence interval 1.45, 4.91, p value 0.0017). Other factors which were tested but showed weak associations that did not reach significant level were age, sex, family history of glaucoma, occupation, and ethnicity. Data was collected in the population by questionnaire on demographic data and awareness, knowledge and health seeking behaviour related to eye care. The details of the questionnaire included age, gender, and occupation, the respondent's definition/understanding of blindness, causes of blindness known, or cause of action taken in face of an eye disease, past history of eye disease and the individual's knowledge and attitudes to glaucoma Cataract ranked as the most common cause of blindness respondents were aware of (77.2% of respondents) followed closely by eye injuries (71.9%). More than half the respondents were also aware of “kooko” (55.7%) and old age related (54.7%). Only 3.6% were aware that glaucoma causes blindness and 1% (23/1785) of the population knew it may be hereditary. About 3.6% (64/1785) were aware of glaucoma as an eye disease but only 0.8% (15/1785) knew that the disease glaucoma is related to optic nerve damage and, or intraocular pressure. A person in the higher occupational levels was 9 times more likely to understand glaucoma than the lower levels (OR 0.11, 95% Cl 0.04-0.3, Pvalue 0.0001). “Kooko" is the indigenous name for piles however it turned out to be an ubiquitous disease that can affect any part of the body including the eye. Nearly half (47%) of respondents used hospital/clinic services while the other half (49%) used chemical stores1, herbalists, or self-prescribed medication from the last 2 service providers. This data confirms the view that significant eye care services are also provided by chemical sellers and herbalists. It also indicates that the people patronised the services of these alternate service providers as much as they patronised the hospitals and clinics using chi square test (P value 0.78). Information was collected independently by questionnaire and interviews from 21 chemical sellers and 60 herbalists identified by informants. The chemists sold only antibiotic eye drops that were used as first line treatment for all cases they saw. The herbalists claimed they treat cataract 82%, eye injuries 82%, kooko 75%, and Apollo 28%2 of respondents. None of them were aware of or treated glaucoma. The routes of administration of the herbal medicine for eye disease were instillation into the eye and nose 50%, instillation into the eye 25%, oral and eye 10%, oral and nasal, and ocular 10% and only oral only 5% of respondents. Although glaucoma prevalence is high in the Akwapim South district the level of awareness is low in the population, chemical sellers, and herbalists who provide about half of eye care services in the district. The level of the initial intra ocular pressure is the most important factor in determining extent of visual damage.