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.

Color-blindness simulation for red-green and blue-yellow ambiguity

Color blindness has important effects on people’s daily activities, since most activities require a discernment between colors. It is very important for engineers and designers to understand how colorblind people perceive colors. Therefore, many methods have been proposed to simulate color perception of people affected by Dichromacy and anomalous Trichromacy. However, the simulation results rarely have been evaluated with the reports of concerned individuals. In first study, we tried to simulate the color perception of people with different types (red and green) and different degrees of color blindness. Different degrees of red-green deficiency is simulated on the 24-plates brand of the Ishihara color vision test kit. Then simulated plates were tested on people with normal color vision. The results show that the simulation performance is better in the case of high degrees of red-green deficiency. There is also a clear difference between the assessment of female and male volunteers. In another study, the perception of the color of people with blue-yellow blindness is also considered. The proposed blue-yellow blind simulation is compared with the result of another research project. The results show that the color perception of individuals with different degrees of blue-yellow blindness can be reconstructed with a reasonable accuracy.

Prevalence of Color Vision Deficiencies

Purpose. The study of color deficiencies prevalence in young people, students of higher educational university.Materials and methods. The study was carried for the half year — fall semester. A total of 1,609 students were examined, aged 17–21. There were 1191 boys and 418 girls. The survey was conducted to determine the health groups in physical training and in various sports sections. An ophthalmologic examination determined refractive disorders and other ocular pathology, which is important for determining health groups. Rabkin polychromatic tables and Neitz color vision test (Neitz Lab (UW Medicine) were used for determining of color deficiencies. The obtained results of these tests were compared in terms of the time spent on the test, the results of the test effectiveness, the determination of dissimulation, and the assessment of the shift in the color spectrum in individuals with impaired color perception.Results. A total of refractive disorders were detected in 856 students (53.2 %). The high degree of myopia was in 40. Disorders of color deficient were noted in 101 students (8.48 %) of 1191 male subjects when using the Neitz color test. Dichromatic eye changes were observed from 2.1 % students: protanopia and deiteranopia were in 0.67 % and 1.43 %. Most of all there were violations with the perception of shades of light brown and light green colors. A third of healthy students noted the impossibility of distinguishing light brown from light gray. This is regardless of the state of refraction. Simultaneous violations of the perception of shades of red, green, yellow and blue were observed in one subject, it was associated with congenital cataracts. In four young people, acquired eye diseases caused. In two girls, violations of the perception of a pastel shade of light green were noted, with one girl (0.24 %) having a violation in two eyes, and was presumably due to a gene anomaly. The second girl had one eye and was associated with partial atrophy of the optic nerve after the optic neuritis.Conclusions. Neitz color test expands the diagnostic possibilities, since in its design it has pastel shades of light green and light brown colors on a gray background, reduces the likelihood of dissimulation, reduces the time of the survey. Neitz color test allows to expand the possibilities for more accurate and differential diagnosis dichromatic and anormal trichromatic subjects and acquired color vision defects.

The burden of color vision defect in Nepal – an iceberg phenomenon

Background: Color vision tests are routinely performed and are mandatory in most part of the world. However, in Nepal and many other developing countries, color vision may often be overlooked. We evaluated a possible burden of color vision in a group of patients who were specifically evaluated for a color vision defects. This study evalutes the awareness of color vision defect among the patients evaluated and highlights the importance of the color vision evaluation. Methods: A sequential group of 73 people from August to September 2017 specifically evalu­ated for color vision defect for recruitment of government employment were evaluated. Ishi­harapseudo-isochromatic plates and Farnsworth-Munsell Dichotomous D-15 test were used for screening. Mean and Standard deviation were used for descriptive analysis of the data. Results: Fifty-seven were male and sixteen were female. The mean age was 23 years (SD ± 3.7). On evaluation of the color vision defect, 9 (12.3%) were found to have total color vision defect (achromatopsia), 3 (4%)-red-green defect and 1(1%) with blue red defect. None of the patients had undergone color vision test at eye hospital previously. There were 4 patients who were registered drivers who had color vision defect. Conclusions: Color vision is an important part of the vision. It should not be ignored.All of the patients evaluated were found to be unware of their condition. Early detection of color vision defects in individuals, if possible, at school level can help them to determine their careers and future endeavors at early stage.

Color vision test to differentiate Alzheimer's disease from vascular dementia

Arnaoutoglou et al. (2017) reported that “Ishihara Color Vision Test – 38 Plate” was useful for the differential diagnosis of dementia between Alzheimer's Disease (AD) and Vascular Dementia (VaD). The authors used sensitivity/specificity analysis, presenting 80.6% and 87.5% to discriminate AD and VaD patients when an optimal (32.5) cut-off value of performance was used. The authors cited a reference of the fact that AD patients suffered from a non-specific type of color blindness (Pache et al., 2003), and I have a query on their study with special reference to statistical method.

OPTIC NEUROPATHY INDUCED BY LOW DOSE OF ETHAMBUTOL: A RARE PRESENTATION

Ethambutol is a bacteriostatic antimicrobial agent used in the treatment of tuberculosis. Optic neuropathy is a potentially severe side effect of ethambutol, which is dose related. Ethambutol-induced optic neuropathy (EON) incidence is 15%, 5% & 1% when taken at 50 mg/kg/day , 25 mg/kg/day & 15 mg/kg/day respectively for 3 months. We report a case of bilateral EON in 20-year-old female after 1 month of exposure to 15 mg/kg/day of ethambutol for tubercular meningitis. Ophthalmologic examination revealed bilateral ill sustained pupillary reactions and optic disc pallor. Deranged color vision test and scotomas on Goldmann perimetry in both eyes, aided in diagnosis.Keywords: Low dose ethambutol, Optic neuropathy, Tuberculosis.