A comparison of computer applications vs conventional colour vision tests: Can they be used interchangeably?

Objective: To determine if three Computer Application colour vision tests (the Insight Colour Vision test, Colour Vision Quiz and the Colour-blind tester MN) can be used in exchange for Conventional methods of colour vision testing. Design and Methodology: A control sample of the general population was selected at random consisting of 50 subjects. The other group, the diseased group included those with diabetes, cataract, glaucoma and retinal diseases, from the Ophthalmology clinic, of the Eric Williams Medical Sciences Complex (EWMSC), and consisted of 25 subjects. All tests were conducted on subjects who volunteered with informed consent. The conventional tests of colour vision, the Ishihara and the Fansworth D15, were trialled on the subjects, then the computer application colour vision tests were tried on the same group. Results: From the tests done, the Colour Vision Quiz and the Colour-blind tester were able to detect the presence of a defect, but unspecific in determining types of defects. Insight colour vision test was found to be as sensitive and specific in detecting colour vision defects among the Control group as the Farnworth D15 test. However it was less accurate in detecting the nature of the colour vision defects among the diseased population. Conclusion: None of the colour vision tests were found to be reliable and reproducible in replacing the conventional methods of colour vision testing.

Frequency and risk factors for pterygium in the Barbados Eye Study

OBJECTIVE: To describe the disrtibution and risk factors for pterygium in the predominantly black population of the Barbados Eye Study, which was based on a random sample for Barbadian-born citizens between the ages of 40 and 84 years. METHODS: The standardized protocol included ophtalmic and other measurements, automated perimetry, lens gradings, fundus photography, and a detailed interview. A 10 percent systematic sample of participants and those meeting specific criteria also received a comprehensive ophthalmologic evaluation. RESULTS: The Barbados Eye Study included 4709 participants, of whom 2978 were referred for an ophthalmologic evaluation and 2781 (93 percent) completed the examination. Cases of pterygium were found among 23.4 percent of 2617 black, 23.7 percent of 97 mixed (black and white), and 10.2 percent of 59 white participants examined. In addition to African ancestry, logistic regression analyses indicated a positive association between pterygium and age (odds ratio [OR], 1.01; 95 percent confidence interval [CI], 1.00-1.02), fewer years of education (OR, 1.43; 95 percent CI, 1.01-2.03), and an outdoor job location (OR, 1.87; 95 percent CI, 1.52-2.29). Having a darker skin complexion (OR, 0.66; 95 percent CI, 0.52-0.83), always using sunglasses outdoors (OR, 0.18; 95 percent CI, 0.06-0.59), and the use of prescription glasses (OR, 0.75; 95 percent CI, 0.60-0.93) were protective factors. CONCLUSIONS: Approximately one quarter of the black participants examined had pterygia, a frequency that was 2.5 to 3 times higher than among whites in the Barbados Eye Study and elsewhere. Pterygium was almost twice as frequent among persons who worked outdoors but only one fifth as likely among those who always used sun glasses outdoors. Educational interventions to modify these potential exposures may assist in preventing pterygium. (AU)

Vision screening in Jamaican children

OBJECTIVE: To determine the prevalence of vision impairment in Jamaican pre-school children. METHODS: A national sample of Jamaican children at the end of the pre-school years was identified using the quarterly Jamaican Labour Force Survey. Each year, this survey identifies 500 pre-school children (1 percent of the national population) using a two-stage stratified random sampling process based on electoral divisions. Over two successive years, a 1 percent and a 0.5 percent sample of children were identified (n=750). A total of 302 children had their distance and near visual acuity assessed. Information on socio-economic status and the parental perception of children's vision was obtained by parental interview. RESULTS: 10.4 Percent of the children were identified as being in need of further ophthalmological referral using the American Academy Screening Guidelines. 4.1 percent of the children were diagnosed as having "low vision" according to the World Health Organization classification. 45.8 percent of the children were unable to identify letters and required lap-card use for evaluation of vision. No gender or socioeconomic differences were identified between those children requiring further ophthalmological assessment and those who did not (p<0.05). Parental perception of children's visual impairment was shown to be an unsatisfactory tool to assist in determining children at high risk for vision impairment. CONCLUSION: Based on the rates of children requiring further ophthalmological evaluation and the rates of low vision identified in this study, the abscence of identifiable risk factors and the inaccuracy of parental perception, all Jamaican pre-school children should be offered vision screening. The inability to identify letters demands that screening programmes must have facilities available for using lap-cards. (AU)

West Indian amblyopia

The visual fields of ten patients with West Indian amblyopia, but with no other sign of neurological disease, have been carefully charted. The scotomata found varied considerably in size, shape and density between the individuals in the group. They were scattered, and quite large with irregular margins, sometimes with small dense defects in their central areas and usually with very shelving edges; a connexion with the blind spot was often present and/or break-through to the periphery. The causative lesions are likely to be subchiasmal. There is a slight resemblance to the field defects in tobacco amblyopia, but as tobbaco does not seem to be a factor in our cases, cyanide poisoning may be the common factor.(Summary)

Bilateral amblyopia occurring in aphakic West Indians

The importance of bilateral ambloyopia as a cause of a poor visual result following cataract extraction in West Indians is assessed. It is submitted that this disorder is more common than previously considered and an incidence of 5 to 7 per cent among 50 to 80-year-old Jamaicans undergoing cataract extraction is suggested. Factors influencing this figure are postulated. Certain clinical aspects of the condition are considered. (AU)