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Visual field constriction as a cause of blindness or visual impairment
I E Murdoch1, B R Jones, S Cousens
1Department of Ophthalmology, Ahmadu Bello University Teaching Hospital, Kaduna, Nigeria.
Bulletin of the World Health Organization
|January 1, 1997
Summary
This study in Nigeria found that 2.7% of individuals were blind and 1.7% visually impaired by acuity. It also identified significant visual impairment due to visual field loss, highlighting the need for updated definitions.
Area of Science:
- Ophthalmology
- Public Health
- Tropical Medicine
Background:
- Onchocerciasis remains a significant public health concern in mesoendemic regions of northern Nigeria.
- Existing definitions for visual impairment do not adequately address visual field loss.
Purpose of the Study:
- To assess the prevalence of blindness and visual impairment due to acuity and visual field loss in Kaduna State, Nigeria.
- To investigate potential criteria for defining visual impairment based on visual field constriction.
Main Methods:
- A cross-sectional study involving 6831 individuals aged 5 years and above in Kaduna State.
- Visual function screening, including acuity testing and Friedmann field analysis.
Main Results:
- Prevalence of bilateral blindness by acuity was 2.7% (185 individuals), and by visual field constriction was 0.4% (28 individuals).
- Visual impairment by acuity affected 1.7% (118 individuals).
- An additional 0.9% (60 individuals) were identified with visual impairment due to field loss using investigated criteria, including peripheral field islands, reduced binocular fields, and concentric constriction.
Conclusions:
- Visual field loss represents a substantial cause of visual impairment and blindness in the studied population.
- Current World Health Organization definitions require revision to include criteria for visual impairment by visual field constriction.
- Further international discussion is needed to establish standardized definitions for visual impairment related to visual field loss.