Blue-yellow colour vision in an onchocercal area of northern Nigeria.
OBJECTIVE
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).


CONCLUSIONS
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.
Kaduna-London Collaboration for Research on Onchocerciasis, Institute of Ophthalmology, London.
A
A
Landers
I E
IE
Murdoch
J
J
Birch
S N
SN
Cousens
O E
OE
Babalola
B
B
Lawal
A
A
Abiose
B R
BR
Jones
D000293:Adolescent; D000328:Adult; D000367:Age Factors; D002648:Child; D002675:Child, Preschool; D003119:Color Perception Tests / Q000379:methods*; D003117:Color Vision Defects / Q000175:diagnosis* / Q000209:etiology / Q000469:parasitology; D003430:Cross-Sectional Studies; D004049:Diethylcarbamazine / Q000009:adverse effects; D005260:Female; D005369:Filaricides / Q000009:adverse effects; D006801:Humans; D008297:Male; D008875:Middle Aged; D009549:Nigeria / Q000208:ethnology; D015827:Onchocerciasis, Ocular / Q000150:complications* / Q000188:drug therapy / Q000208:ethnology; D012307:Risk Factors; D012423:Rural Health; D014792:Visual Acuity
D005369:Filaricides; D004049:Diethylcarbamazine