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Blindness: how to assess numbers and causes?
O E Babalola1, I E Murdoch, S Cousens
1Rachel Eye Centre, Abuja, Nigeria.
The British Journal of Ophthalmology
|February 25, 2003
Summary
Simple methods like perceived visual status surveys can accurately estimate blindness prevalence, particularly for cataract. Examining all visually disabled individuals in a community also provides reliable cause-specific prevalence data for eye care planning.
Area of Science:
- Ophthalmology
- Public Health
- Epidemiology
Background:
- Traditional blindness surveys use population-wide census and examination, requiring large sample sizes due to low prevalence.
- Estimating blindness prevalence and causes in communities presents challenges due to the rarity of the condition.
Purpose of the Study:
- To compare the accuracy of different methods for assessing blindness prevalence and its causes.
- To evaluate simpler, potentially more cost-effective methods for blindness surveys.
Main Methods:
- Three blindness assessments were conducted: perceived visual status (PVS) via census questions, examination of the visually disabled (EVD), and whole community examination (WCE).
- Prevalence and cause-specific blindness data were collected and compared across the three methods.
Main Results:
- Blindness prevalence estimates were 2.7% (PVS), 3.6% (EVD), and 3.1% (WCE) in a population of 8139.
- Perceived visual status (PVS) accurately identified cataract as a cause but was less representative for other causes.
- Examination of the visually disabled (EVD) provided cause-specific estimates close to WCE, with slight under-representation of glaucoma and optic atrophy.
Conclusions:
- Asking individuals about their vision status may be adequate for estimating blindness due to cataract, informing eye care strategies.
- Community-based examination of visually disabled individuals offers a practical alternative for obtaining reasonably accurate cause-specific prevalence estimates without extensive surveys.