Landers A, Murdoch IE, Birch J, Cousens SN, Babalola OE, Lawal B, Abiose A, Jones BR. Blue-yellow colour vision in an onchocercal area of northern Nigeria.
Br J Ophthalmol 1998;
82:510-6. [PMID:
9713057 PMCID:
PMC1722603 DOI:
10.1136/bjo.82.5.510]
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Abstract
AIM
To determine if the City University Tritan Test is a useful addition to visual function assessment in rural communities in northern Nigeria.
METHODS
The study was a cross sectional survey. The participants were 8394 people, aged 5 years and over, living in 37 rural communities, mesoendemic and nonendemic for onchocerciasis, in Kaduna State in northern Nigeria. The main outcome measures were the detection of a defect in blue-yellow colour vision by two criteria: (1) failure with the City University tritan screening plates; (2) failure with the City University grading plates to identify severe tritan defects.
RESULTS
91% of those aged 10 years and above could perform the test. Below this age, there were difficulties in comprehension. The test showed good inter- and intraobserver agreement. After adjustment for confounders the odds of failing the screening plates were significantly increased in the presence of optic atrophy or glaucoma (3.55 (2.48-5.08) and 15.9 (4.22-60.2) respectively). There was a greater increase in the adjusted odds of failing the grading plates in the presence of optic atrophy or glaucoma (5.30 (2.97-9.45) and 8.87 (1.61-48.7) respectively). Cataract had a smaller effect on the screening plates, adjusted odds 1.63 (0.95-2.80).
CONCLUSION
Blue-yellow colour vision testing is a useful addition to visual function assessment in those aged 10 years and above in rural northern Nigeria, particularly in the detection of optic nerve disease.
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