Color vision deficiency in a middle-aged population: the Shahroud Eye Study

Prevalence and population genetic data of colour vision deficiency among students from selected tertiary institutions in Lagos State, Nigeria

Background

Colour vision deficiency (CVD), also referred to as colour blindness, is the failure or decreased ability to distinguish between certain colours under normal lighting conditions. It is an X-linked genetic disorder with varying degrees of prevalence in different populations. There is presently no report on the prevalence of CVD among students of the selected tertiary institution. Hence, the present study was aimed at determining the occurrence and genetics of CVD among students from designated tertiary institutions in Lagos state. A cross-sectional survey was employed in recruiting 1191 study subjects from three tertiary institutions in Lagos, Nigeria.

Results

The overall occurrence of CVD among the study participants was 2.85%. There were 24 (4.29%) males and 10 (1.58%) females affected. Among the colour vision deficient individuals, 18 (1.51%) and 16 (1.34%) were deuteranomalous and protanomalous, respectively. Also, the prevalence of CVD varies across ethnic groups of the studied subjects with the highest occurrences (3.57%) observed in the Yoruba ethnic subpopulation and the least (1.45%) among the Hausas.

Conclusions

More males than females were found to be colour vision deficient, and there were more deutans than protans. Early screening for CVD should be encouraged among school children to guide the choice of future profession and help mitigate work hazards resulting from being colour deficient.

Age-related changes of color visual acuity in normal eyes

Purpose

To evaluate the age-related change in color visual acuity (CVA) in normal eyes.

Methods

In total, 162 normal eyes (162 subjects, women: 52, men: 110, age range: 15–68 years) with best-corrected visual acuity (BCVA) ≥20/13 were enrolled. Fifteen colors from the New Color Test (chroma 6) were applied to Landolt “C” rings, white point D65 was applied as background, and a luminance of 30 cd/m² was set for both the rings and the background. These rings were used to measure the chromatic spatial discrimination acuity as the CVA value, while changing the stimulus size. Correlations of the CVA value of each color and age were evaluated. Mean CVA values of all 15 colors (logarithm of the minimum angle of resolution) were compared between age groups in 10-year increments.

Results

Nine CVA values (red, yellow-red, red-yellow, green, blue-green, green-blue, purple, red-purple, and purple-red) were negatively correlated with age (all p<0.05); the remaining six (yellow, green-yellow, yellow-green, blue, purple-blue, and blue-purple), as well as BCVA were not. The age groups with the best to worst mean CVA values of 15 colors were as follows: 20–29 (mean ± standard deviation, 0.303 ± 0.113), 30–39 (0.324 ± 0.096), 10–19 (0.333 ± 0.022), 50–59 (0.335 ± 0.078), 40–49 (0.339 ± 0.096), and 60–69 (0.379 ± 0.125) years. There were statistically significant differences between mean CVA values of the following groups: 20–29 and 40–49 years; 20–29 and 60–69 years; 30–39 and 60–69 years (all p<0.01).

Conclusions

The CVA values related to the medium/long-wavelength-sensitive cones were more susceptible to aging than those related to the short-wavelength-sensitive cones. This differed from previous reports, and may be related to the difference in the range of foveal cone function evaluated with each examination.

A pathological indicator for dysthyroid optic neuropathy: tritan color vision deficiency

Purpose

To investigate the sensitivity of the color vision test by Arden in patients with dysthyroid optic neuropathy (DON) to improve diagnosis.

Methods

In this observational, retrospective study, we included the medical records of 92 eyes (48 patients) with diagnosis of DON between 2008 and 2019 in order to evaluate the full spectrum of findings from the color vision test by Arden, and to determine potential importance of this test. Thirty-five patients were female, and 13 patients were male. The mean age was 58.0 years (range: 34–79) at the time of the DON diagnosis.

Results

Forty-one eyes displayed relatively good BCVA with ≤ 0.2 LogMAR. We found a protan value exceeding the threshold of ≥ 8% in 57 eyes (30 patients) at the time of the diagnosis. The sensitivity of protan was 61.9% (95% CI 51.2–71.8%), while that of tritan was a striking 98.9% (95% CI 94.1–99.9%).

We discovered one pathological sign, tritan deficiency (based on a threshold of ≥ 8%) consistently in all eyes but one at the time of the diagnosis, regardless of the visual field defects or any changes in best-corrected visual acuity (BCVA).

Conclusion

We found blue-yellow (tritan) deficiency, to be a sensitive and reliable indicator of dysthyroid optic neuropathy. We conclude that, in cases with suspected DON, a color vision test that can detect tritan deficiency is an essential tool for the adequate assessment, diagnosis, and treatment of DON.

The Change in Color Vision with Normal Aging Evaluated on Standard Pseudoisochromatic Plates Part-3

Purpose: To evaluate the influence of aging on color vision in a large normal population using Standard Pseudoisochromatic Plates part-3 (SPP-3), which is a pseudoisochromatic plate test used to detect congenital or acquired color vision deficiency (CVD).Materials and methods: We retrospectively reviewed SPP-3 test results of 23,565 normal eyes of 23,565 subjects (women: 12,035; men: 11,530), who were examined between July 1993 and December 2010. The subjects had a mean age of 46.9 ± 18.5 years, ranging from 5 to 89 years, and they were evaluated following categorization into age groups with five-year increments. Subjects whose best-corrected visual acuity (BCVA) was 20/20 or better, with no history of ocular diseases, were included. Subjects with congenital CVD were excluded.Results: We found a negative correlation between age and the total number of correct answers in SPP-3 (Spearman's correlation coefficient, r = -0.5743; p < .0001). The total number of correct answers was the highest in subjects aged 10-14, 15-19, and 20-24 years (17.2 ± 0.9 [mean ±SD]). The total number of correct answers of these groups had significant differences from those in the 5-9 years age group and those aged >30 years (Dunn's post-hoc test: p < .0001). Among the 19 detection numerals in SPP-3, we found that the correct answer rates of six numerals decreased with aging, and the colors of the numerals and their backgrounds all located parallel to the tritanopic confusion line.Conclusions: Using SPP-3, we confirmed that aging influenced color vision, even in normal eyes with a good BCVA (20/20 or better). The total number of correct answers of SPP-3 was the highest in subjects aged 10-24 years and had already begun to decline in those in their 30s.

Subclinical dysthyroid optic neuropathy: tritan deficiency as an early sign of dysthyroid optic neuropathy

PURPOSE

The aim of this research was to investigate the subclinical findings of dysthyroid optic neuropathy (DON) and to look for early indicators for optic nerve compression in patients with Graves' orbitopathy.

PATIENTS AND METHODS

In this observational, retrospective study, the medical charts of 24 patients (32 eyes) with a diagnosis of DON between 2008 and 2019 were included. Our goal was to identify potential pathological signs in patients with DON prior to the definitive diagnosis of DON.

RESULTS

We discovered that the earliest pathological sign in the subclinical cases was tritan deficiency obtained with a standardised colour vision test by Arden. In all cases but one, regardless of the visual field (VF) defects, the tritan values were pathological (based on a threshold of ≥8%) in the subclinical phase. The mean tritan value was 19.12% (range 6.9-80.8%) at the time of the subclinical phase and 32.16% (range 6.3-100.0%) at the time of the diagnosis of DON. The sensitivity of the colour vision test was 20% for protan and 96.67% for tritan in the subclinical phase. At the time of the definitive diagnosis of DON, the sensitivity of protan was 48.15% compared to 96.30% for tritan.

CONCLUSION

We found that changes in vision affecting the blue-yellow (tritan) colours resulting from the compression of optic nerve, even in affected patients with normal VF tests, are a reliable early sign of DON.

Prevalence of Color Vision Deficiency in an Adult Population in South Korea

SIGNIFICANCE

Large differences in failure rates for color vision screening have been reported among different regional groups. However, color vision deficiency prevalence in Korea has only been investigated within a small area of the country.

PURPOSE

This study examines the prevalence of failing a color vision screening and its sex-related differences using a sample that is representative of the whole Korean population.

METHODS

This population-based cross-sectional study evaluated 2686 subjects (age, 19 to 49 years) who participated in the sixth Korea National Health and Nutrition Examination Survey (2013). Color vision deficiency was assessed using the Hardy-Rand-Rittler (HRR) test by an ophthalmologist. According to standard criteria for the HRR, it classified each subject as color normal, protan, deutan, tritan, or unclassified color vision loss. All participants had comprehensive medical evaluations and ocular history taken.

RESULTS

The weighted overall prevalence of color vision deficiency in the Korean population was 3.9% (95% confidence interval, 3.0 to 5.4%). The prevalence of color vision deficiency was higher in male participants (6.5%) than in female participants (1.1%). Among all participants, deutan deficiency (2.5%) had a higher prevalence than did protan deficiency (0.4%). For male participants who failed the HRR screening, deutan-type deficiency was detected most often (64.2%), whereas an unclassified color vision deficiency type was the most common (52.9%) among female participants who failed the HRR screening. As expected, male participants were more likely to fail the HRR screening compared with female participants (prevalence ratio, 6.08; 95% confidence interval, 3.61 to 10.26).

CONCLUSIONS

This large population-based study of color vision deficiency among Koreans gives the most accurate estimate of failing a color vision screening test to date and provides useful information for planning adaptive strategies.

The prevalence of color vision deficiency in the northeast of Iran

PURPOSE

To determine the prevalence of color vision deficiency (CVD) in the northeast of Iran.

METHODS

This cross-sectional, population-based study was conducted in Mashhad, in the northeast of Iran. Multistage cluster sampling was used for selecting the participants. After preliminary screening, the subjects underwent a complete ophthalmic examination. The examination included the measurement of visual acuity, refraction, and slit-lamp biomicroscopy. The Farnsworth D-15 test was used to detect CVD. The color vision test was done with the best optical correction.

RESULTS

Of the 4453 invitees, 3132 participated in the study (response rate: 70.4%). The overall prevalence of CVD in this study was 13.93% [95% confidence interval (CI): 12.44-15.41]. The prevalence of CVD in males and females was 15.85% (95% CI: 13.26-18.44) and 12.96% (95% CI: 11.22-14.71), respectively. The most prevalent types of CVD were tritanopia (6.96%; 95% CI: 5.84-8.08), deuteranopia (3.92%; 95% CI: 3.14-4.70) and tritanomalous (2.21%; 95% CI: 1.55-2.86), respectively. According to the results of logistic regression, the odds of having protanopia were higher in females than males [Odds ratio (OR) = 4.80; 95% CI: 1.20-19.18]. The odds of having deuteranopia were lower in females than males (OR = 0.52; 95% CI: 0.35-0.76). The odds of having CVD were lower in 16-30 (OR = 0.52; 95% CI: 0.37-0.73) and higher in 46-60 (OR: 1.41; 95% CI: 1.01-1.97) year age groups compared to 7-15 year age group. The odds of having tritanopia in 16-30 and 46-60 year age groups was 0.56 (95% CI: 0.35-0.90) and 1.79 (95% CI: 1.19-2.67) compared to 7-15 year age groups, respectively.

CONCLUSION

The prevalence of CVD was high in this study, especially in males and people over 46 years of age. Planning for involvement of ocular disease control programs in health care systems can be helpful in the reduction of CVD and improving the quality of life in affected patients.

Color Vision Losses in Autism Spectrum Disorders

Autism spectrum disorders (ASDs) are neurodevelopmental conditions characterized by impairments in social/communication abilities and restricted behaviors. The present study aims to examine color vision discrimination in ASD children and adolescents without intellectual disability. The participants were also subdivided in order to compare color vision thresholds of autistic participants and those who achieved diagnostic criteria for Asperger Syndrome (AS). Nine subjects with autism, 11 participants with AS and 36 typically developing children and adolescents participated in the study. Color vision was assessed by the Cambridge Color Test (CCT). The Trivector protocol was administered to determine color discrimination thresholds along the protan, deutan, and tritan color confusion lines. Data from ASD participants were compared to tolerance limits for 90% of the population with 90% probability obtained from controls thresholds. Of the 20 ASD individuals examined, 6 (30%) showed color vision losses. Elevated color discrimination thresholds were found in 3/9 participants with autism and in 3/11 AS participants. Diffuse and tritan deficits were found. Mechanisms for chromatic losses may be either at the retinal level and/or reflect reduced cortical integration.

Frequency of color blindness in pre-employment screening in a tertiary health care center in Pakistan

Objective:

To describe the frequency of color vision deficiency among Pakistani adults presenting for pre-employment health screening in a tertiary care hospital.

Methods:

The cross-sectional study was carried out at the Aga Khan University Hospital, Karachi, and the data was collected for color vision deficiency, age, gender, and job applied for from pre-employment examination during 2013-2014. IBM SPSS 20 was used for statistical analysis.

Results:

Three thousand four hundred and thirty seven persons underwent pre-employment screening during 2013 and 2014; 1837 (53.44%) were males and 1600 (46.65%) females. The mean age was 29.01 (±6.53) years. A total of 0.9% (32/3437) persons had color vision deficiency with male being 1.4% and female 0.4%.

Conclusion:

Color vision deficiency was observed in 0.9% of candidates screened for pre-employment health check up in a tertiary care hospital. The color vision deficiency was predominantly present in male individuals.

Acquired color vision deficiency

Acquired color vision deficiency occurs as the result of ocular, neurologic, or systemic disease. A wide array of conditions may affect color vision, ranging from diseases of the ocular media through to pathology of the visual cortex. Traditionally, acquired color vision deficiency is considered a separate entity from congenital color vision deficiency, although emerging clinical and molecular genetic data would suggest a degree of overlap. We review the pathophysiology of acquired color vision deficiency, the data on its prevalence, theories for the preponderance of acquired S-mechanism (or tritan) deficiency, and discuss tests of color vision. We also briefly review the types of color vision deficiencies encountered in ocular disease, with an emphasis placed on larger or more detailed clinical investigations.

Clinical color vision testing and correlation with visual function

PURPOSE

To determine if Hardy-Rand-Rittler (H-R-R) and Ishihara testing are accurate estimates of color vision in subjects with acquired visual dysfunction.

DESIGN

Assessment of diagnostic tools.

METHODS

Twenty-two subjects with optic neuropathy (aged 18-65) and 18 control subjects were recruited prospectively from an outpatient clinic. Individuals with visual acuity (VA) <20/200 or with congenital color blindness were excluded. All subjects underwent a comprehensive eye examination including VA, color vision, and contrast sensitivity testing. Color vision was assessed using H-R-R and Ishihara plates and Farnsworth D-15 (D-15) discs. D-15 is the accepted standard for detecting and classifying color vision deficits. Contrast sensitivity was measured using Pelli-Robson contrast sensitivity charts.

RESULTS

No relationship was found between H-R-R and D-15 scores (P = .477). H-R-R score and contrast sensitivity were positively correlated (P = .003). On multivariate analysis, contrast sensitivity (β = 8.61, P < .001) and VA (β = 2.01, P = .022) both showed association with H-R-R scores. Similar to H-R-R, Ishihara score did not correlate with D-15 score (P = .973), but on multivariate analysis was related to contrast sensitivity (β = 8.69, P < .001). H-R-R and Ishihara scores had an equivalent relationship with contrast sensitivity (P = .069).

CONCLUSION

Neither H-R-R nor Ishihara testing appears to assess color identification in patients with optic neuropathy. Both H-R-R and Ishihara testing are correlated with contrast sensitivity, and these tests may be useful clinical surrogates for contrast sensitivity testing.