Prevalence of colour vision deficiency in the Republic of Ireland schoolchildren and associated socio-demographic factors.

CLINICAL RELEVANCE: Early screening is essential to counsel schoolchildren with congenital colour vision deficiency (CVD) in determining their future career path and to advise teachers of the impact of CVD on classroom difficulties. BACKGROUND: Congenital CVD is an X-linked genetic abnormality relatively commonplace in humans. This study aimed to determine the prevalence of congenital CVD in the Republic of Ireland schoolchildren and associated socio-demographic factors. METHODS: A total of 1,626 schoolchildren (882 boys and 744 girls), in two age groups (728 aged 6-7-years and 898 aged 12-13-years) were examined from randomly selected schools. Colour vision testing was carried out using the Richmond Hardy-Rand-Rittler pseudoisochromatic test for colour vision (fourth edition); diagnostic plates were used to determine CVD type and extent if participants failed to identify symbols on the screening plates. RESULTS: CVD was detected in 73 boys (8.3 per cent, 95% confidence interval (CI) 6.6-10.3) and in 13 girls (1.8 per cent, 95% CI 1.0-3.1, p < 0.001). As expected, deutan (boys 4.8 per cent, girls 0.8 per cent) was the most common type of CVD, followed by protan (boys 1.7 per cent, girls 0.1 per cent), unclassified red/green CVD (boys 1.2 per cent, girls 0.8 per cent) and then tritan (boys 0.5 per cent). One case of achromatopsia was detected based on failure on all diagnostic plates. Traveller participants (boys 21.0 per cent, girls 8.6 per cent) had a higher CVD prevalence than their White non-Traveller (boys 7.2 per cent, girls 1.0 per cent) and non-White (boys 5.4 per cent, girls 1.1 per cent) counterparts (odds ratio 3.00, 95% CI 1.1-8.1, p = 0.006). In boys, CVD was also associated with twin birth (odds ratio 2.7, 95% CI 1.1-6.7, p = 0.03) and low birthweight (p = 0.04). CONCLUSION: This investigation of CVD in the Republic of Ireland schoolchildren should alert clinicians to the association between CVD and Traveller ethnicity, twin birth and lower birthweight. The prevalence of CVD found was similar to previous studies involving predominantly White populations and higher among Traveller participants; hence, counselling regarding inherited anomalies in the Traveller community is recommended. Early screening is essential to counsel schoolchildren with CVD in determining their future career path and to advise teachers of the impact of CVD on classroom difficulties.

Can Protanopia Be Correctly Diagnosed in Clinical Practice? An Evaluation of Diagnosis by Four Screening Tests.

SIGNIFICANCE: Protanopia is a color vision deficiency (CVD) that is unacceptable for certain occupations. This study compares simultaneously for the first time the ability of three recently revised or developed clinical tests of color vision with the Ishihara test to diagnose protanopia from other color vision deficiencies. PURPOSE: The objectives were to examine the ability of four clinical tests to differentiate (1) between protan and deutan CVDs in patients with protanopia and deuteranopia, and (2) protanopes and deuteranopes as "strong" deficiencies. METHODS: The Hardy-Rand-Rittler (4th ed.), City University (3rd ed.), Ishihara, and Mollon-Reffin tests were evaluated against the Oculus Heidelberg Multi-Color anomaloscope for 18 protanopes and 9 deuteranopes. Diagnosis by anomaloscopy was subsequent to administration of screening tests. RESULTS: The Ishihara test misdiagnosed all 18 protanopes as having a deutan deficiency. In contrast, the Hardy-Rand-Rittler and Mollon-Reffin tests correctly identified protan CVD in 100% of protanopes. No screening test was able to reliably diagnose protanopia on the basis of a strong protan CVD. CONCLUSIONS: The Ishihara test is not suitable for screening for protanopia; its failure to diagnose protanopes as having a protan CVD was far greater than that in previous studies. The Hardy-Rand-Rittler and Mollon-Reffin are the most reliable tests for this purpose. None of the screening tests were able to reliably differentiate dichromacy from strongly anomalous trichromacy.

Clinical applicability of the Macular Degeneration Detection Device (MDD-2): a novel photostress recovery measurement device.

BACKGROUND: Diseases affecting the macula, such as age-related macular degeneration (AMD), diabetic retinopathy and central serous retinopathy can result in impaired photostress recovery time (PSRT) despite normal visual acuity and fundoscopic appearance. The MDD-2 Macular Degeneration Detection Device is a novel flash photostress recovery device. In this study, we examine the repeatability of the MDD-2 in a normal population and its suitability for incorporation into routine clinical practice. METHODS: One hundred (60 female) subjects (mean age 35 ± 8 years; range 18 to 66 years) were recruited to partake in this study. The photostress recovery time was measured using the MDD-2 on three occasions in the dominant eye and one final occasion in the non-dominant eye to assess measurement repeatability. All subjects were in good ocular health. Visual acuity and iris colour were recorded for each participant. RESULTS: Repeated measures analysis of variance revealed a statistically significant learning effect on intra-measurement repeatability (p < 0.01). Although paired t-test analysis revealed statistically significant differences between repeated measures both within and between eyes (p < 0.05 for all) the correlation between repeat measurements is statistically significant (p < 0.05 for all), and the coefficient of repeatability reaches clinically acceptable levels once the initial photostress recovery time, which demonstrated increased variability and latency compared to all subsequent measures, is excluded. CONCLUSION: The MDD-2 provides highly repeatable measurements of photostress recovery time among young naïve subjects, following verbal explanation of the task and only one 'practise' measurement. The measurement is also highly repeatable between eyes, providing a potential immediate clinical biomarker of ocular health.

The relationship between macular pigment and visual performance.

This study was designed to assess whether macular pigment optical density (MPOD) is associated with visual performance. One hundred and forty-two young healthy subjects were recruited. Macular pigment optical density and visual performance were assessed by psychophysical tests including best corrected visual acuity (BCVA), mesopic and photopic contrast sensitivity, glare sensitivity, photostress recovery time (PRT). Measures of central visual function, including BCVA and contrast sensitivity, were positively associated with MPOD (p<0.05, for all). Photostress recovery and glare sensitivity were unrelated to MPOD (p>0.05). A longitudinal, placebo-controlled and randomized supplementation trial will be required to ascertain whether augmentation of MPOD can influence visual performance.