Assessment of Colour Blindness and Erythrocyte G6PD Enzyme Status among the School Children of Dhaka City

Abstract

Background: Visual impairment due to colour blindness is an unusual suffering of the school children. It may be associated with erythrocyte G6PD enzyme deficiency. Objective: To find out defective vision due to colour blindness in apparently healthy school children and to measure erythrocyte G6PD enzyme level among them. Methods: This cross sectional study was carried out in the Department of Physiology, SSMC from 1 st July 2007 to 31 st June 2008. Five hundred (500) apparently healthy school children of old Dhaka, age ranged from 6 to 12 years irrespective of gender and race was selected as study population. Colour vision test was done by Ishihara's test. Erythrocyte G6PD enzyme was measured among the colour blind children. All the results were compared to that of children with normal colour vision. Results: Five male children were detected to have partial red-green type of colour blindness. The percentage of colour blindness was statistically not significant (p>0.05) when compared to that of children with normal colour vision. Mean erythrocyte G6PD enzyme level of colour blind children was significantly lower (p<0.05) compared to that of children with normal colour vision. Presence of G6PD enzyme deficiency among the colour blind children did not show any clinical abnormalities might be due to different non symptomatic G6PD variants. Conclusion: Visual defect due to colour which blindness particularly red-green type might be present in apparently healthy school children associated with erythrocyte G6PD enzyme deficiency.

Prevalence of color vision deficiency among school children in Wolkite, Southern Ethiopia

“…Thus, the possible mechanism of colour blindness might be congenital. A similar finding was also reported by other study [ 16 ].…”

“…Majority of the colour blind children of present study were Muslim by religion, which is supported by other study [ 16 ]. Colour blindness is common among the Muslim populations due to frequently practice of consanguinity of marriage among them [ 16 ].…”

“…This finding was also comparable with a study done in Thailand, which reported a prevalence rate of 4.2% [ 18 ]. However, the result of this study is higher than the incidence of colour blindness among school children reported as 1.9% [ 3 ] and 2.1% [ 19 ] in Nepal, 2.6% in Nigeria [ 20 ] and 1% in Bangladesh [ 16 ]. A higher prevalence of 5.28% was reported in India among Manipuri Muslims of both sexes [ 5 ].…”

“…This finding is supported by several studies [ 1 , 13 , 20 , 21 ]. While other studies [ 3 , 16 , 19 ] showed that colour blindness was found only among the males. Although, the male: female prevalence ratio is markedly different in different studies, several published literatures showed a higher prevalence of CVD among males compared to females.…”

“…Study done by Bowmaker [ 23 ] indicated that the most common form of anomalous colour vision is deuteranomaly. It was suggested that green colour receptor is commonly affected than other cone receptors [ 16 , 23 ].…”