Field changes on automated Humphrey’s field analyzer in tuberculosis following ethambutol therapy

This study was conducted to evaluate the visual field changes in tubercular patients on anti-tubercular therapy and to assess the reversibility of these changes after the discontinuation therapy. This study was conducted as a prospective analytical study at tertiary care centres in Bhopal and Jabalpur on all newly detected tuberculosis patients. Ocular history, relevant history was recorded and detailed ocular examination was done at the time of presentation, before initiating ATT. All the patients were followed up periodically till the cessation of treatment and three months thereafter. A total of 40 cases of newly diagnosed tuberculosis were registered with mean age of 38.4±13.99 years. We documented significant deterioration in visual acuity after 3 months of initiation of therapy. Once the ATT was stopped, the improvement in visual acuity was statistically significant 3 months after the cessation of ATT as compared to visual acuity 3 months after initiation of ATT (p<0.05). But residual visual impairment even after stoppage of ATT was observed. Color vison and visual field defects were observed in higher proportions of eyes following initiation of ethambutol which improved significantly after 3 months of cessation of ATT (p<0.05). Ethambutol, even in recommended dose according to DOTS, has been associated with ocular toxicity which manifests in the form of painless progressive loss of vision, color vision defects and visual field defects. Though these changes are usually reversible, few patients have irreversible damage. Thus, patients receiving ethambutol must be explained regarding these effects and followed up periodically.

Testing Color Vision in Children

It is important to screen for acquired or hereditary color vision defects as early as possible. Color vision is a critical part of the early learning experience, and children who have color deficiencies may have difficulties compared to their peers if there is color-based schoolwork. It becomes important for career interests/goals for older children as some jobs may require normal color vision. Hereditary red-green deficiencies are X-linked and therefore affect approximately 8% of males and less than 1% of females. Acquired color vision defects and blue-yellow defects are rare in the pediatric population; therefore, these conditions will be discussed minimally in this chapter. Infants are able to discern color by 2-3 months of age, but accurate color naming may not develop until 4-6 years of age. Screening tests are sensitive, fast, and easy to administer. If a deficiency is suspected through screening, further testing must be evaluated in order to determine the type and severity of the color vision defect. Color vision is typically tested starting at age 3 years and up.

Color Vision in the Gas Station Workers of Isfahan City: A Quantitative Analysis With the Farnsworth D15 Color Test

Background and Objectives: The color vision evaluation of gas station workers in Isfahan City. Methods: This cross-sectional comparative study was performed on workers at gas stations in Isfahan; all the workers were men. The participants were divided into two 40-people groups of exposure and non-exposure (the members of the fuel sales department). The participants had better vision than 8/10 and no underlying problems or eye disease. Besides, examination, including color vision was performed for all subjects. Color vision was assessed using the D15 test under high to medium light conditions. Also, the color vision test was performed monocularly. Then, the obtained data were analyzed using SPSS V. 22. Results: The two study groups significantly differed in terms of color vision impairment index (P <0.001). Also, more color vision defects were seen in the group exposed to gasoline. The color confusion index (as the indicator of color vision defects) were 1.485 and 1.129 in exposure and non-exposure to gasoline groups, respectively. Thus, color vision defects were significantly higher in the exposure to gasoline group, compared with the control group. Conclusion: The results of this study showed a difference in color vision index between the two groups. Therefore, long-term exposure to organic solvents, such as gasoline in fuel stations may cause color vision loss.

Prototyp eines Bildschirmfarbtests

Purpose. The purpose of this study is to develop a new digital colour vision test. Material and Methods. Based on the principle of metamerism, a digital testing strategy was developed for efficient measurement of colour vision. Twentyfive subjects participated in the study, 21 of whom had normal colour vision and four of whom had a congenital colour vision disorder. Differences in colour vision were examined by monocular presentation of halfquadrants of different hues and degrees of saturation, and the algorithm calculated the colour vision defects that occurred based on the subjects’ responses. The following colour vision values were assigned from the data: a colour scale range of 2.76 – 7.18 for normal colour vision and greater than 7.18 for colour sense disorders. A second new colour scale assessed the type of colour vision disturbance: in the range of 0 – 0.3 were values for a deuteranomaly, in the range of 0.6 – 1.0 were values for a protanomaly, and a value of 1.0 corresponded to a tritanomaly. Results. The difference in colour vision between subjects with normal colour vision and those with a colour vision defect was confirmed (p < 0.001) by measuring the type and the extent of the colour vision disorder was determined. In the group of subjects with normal colour perception, a mean colour scale value of 3.41 ± 0.52 was determined. The extent of colour sense disturbance for the subjects with colour vision impairment was values of 7.18 – 14.33 according to the colour scale, indicating greater variability. Conclusion. The developed algorithm provided meaningful results regarding the colour perception of the test persons. It was possible to differentiate between normal colour vision and colour vision disorder could be shown. Furthermore, the variation between subjects with normal colour vision could be evaluated. Keywords. Colors, colour vision, colour sense disorders, colour test, software algorithm

Identification of a novel RPGR mutation associated with X-linked cone-rod dystrophy in a Chinese family

Background Cone-rod dystrophy (CORD) is a group of inherited retinal dystrophies, characterized by decreased visual acuity, color vision defects, photophobia, and decreased sensitivity in the central visual field. Our study has identified a novel pathogenic variant associated with X-linked cone-rod dystrophy (XLCORD) in a Chinese family. Methods All six family members, including the proband, affected siblings, cousins and female carriers, have underwent thorough ophthalmic examinations. The whole exome sequencing was performed for the proband, followed by Sanger sequencing for spilt-sample validation. A mammalian expression vector (AAV-MCS) with mutated retinitis pigmentosa GTPase regulator (RPGR) sequence was expressed in HEK293 T cells. The mutated protein was verified by Western blotting and immunohistochemistry. Results A novel mutation in the RPGR gene (c.2383G > T, p.E795X) is identified to be responsible for CORD pathogenesis. Conclusions Our findings have expanded the spectrum of CORD-associated mutations in RPGR gene and serve as a basis for genetic diagnosis for X-linked CORD.

Structural and Functional Characteristics of Color Vision Changes in Choroideremia

Color vision is considered a marker of cone function and its assessment in patients with retinal pathology is complementary to the assessments of spatial vision [best-corrected visual acuity (BCVA)] and contrast detection (perimetry). Rod-cone and chorioretinal dystrophies—such as choroideremia—typically cause alterations to color vision, making its assessment a potential outcome measure in clinical trials. However, clinical evaluation of color vision may be compromised by pathological changes to spatial vision and the visual field. The low vision Cambridge Color Test (lvCCT) was developed specifically to address these latter issues. We used the trivector version of the lvCCT to quantify color discrimination in a cohort of 53 patients with choroideremia. This test enables rapid and precise characterization of color discrimination along protan, deutan, and tritan axes more reliably than the historically preferred test for clinical trials, namely the Farnsworth Munsell 100 Hue test. The lvCCT demonstrates that color vision defects—particularly along the tritan axis—are seen early in choroideremia, and that this occurs independent of changes in visual acuity, pattern electroretinography and ellipsoid zone area on optical coherence tomography (OCT). We argue that the selective loss of tritan color discrimination can be explained by our current understanding of the machinery of color vision and the pathophysiology of choroideremia.

Vision screening among hearing-impaired school children in Biratnagar, Nepal

Background: The prevalence of hearing impairment in Nepal is 16.5%, affecting approximately 2.71 million people. Deaf children are visually dependent, and even a mild refractive error may cause visual discomfort. The goal of this study was to determine the need for vision screenings in schools for the hearing impaired in Biratnagar, Nepal. Methods: A cross-sectional study was conducted with permission from Birat Deaf Secondary School, Biratnagar, Nepal. A total of 130 hearing-impaired students were examined. Non-invasive, comprehensive optometric examinations were performed to detect visual disorders. When a more detailed evaluation was needed, the students were referred to the Pediatric Ophthalmology Department, Biratnagar Eye Hospital Biratnagar, Nepal. Results: Of the 130 hearing-impaired students, 58 (44.6%) were male and 72 (55.4%) were female. The mean ± standard deviation of age was 16.03 ± 3.8 years (range 6–25 years). Twenty-one (16.1%) students had refractive errors: 13 (10%) had myopia, 7 (5.4%) had hyperopia, and 1 (0.8%) had anisometropia. In the cover test, 88 (67.7%) had orthophoria, 19 (14.6%) had exophoria, 11 (8.5%) had esophoria, 5 (3.85%) had exotropia, and 3 (2.3%) had esotropia. Cover tests were not performed in 4 (3.1%) students, as they were unable to fixate due to nystagmus or decreased vision. On ocular examination, 20 (15.3%) students had anterior segment abnormalities, including lid abnormality, conjunctivitis, Bitot’s spots, pterygium, corneal opacity, and lenticular opacity. Posterior segment or retinal abnormalities were found in four students with one having Usher syndrome. Color vision defects, nystagmus, and amblyopia were found in 8 (6.1%), 2 (1.5 %), and 1 (0.8%), respectively. Conclusions: The findings of the present study reflect the need of periodic vision screenings in schools for the hearing impaired in Nepal. These children are at a high risk of vision impairment. How to cite this article: Sah SK, Thakur R, Adhikari PR. Vision screening among hearing-impaired school children in Biratnagar, Nepal. Med Hypothesis Discov Innov Optom. 2021 Spring; 2(1): 36-40. DOI: https://doi.org/10.51329/mehdioptometry123

CLINICAL PROFILE, RISK FACTORS AND VISUAL OUTCOME IN PATIENTS OF ACUTE CENTRAL SEROUS CHORIORETINOPATHY IN A TERTIARY HEALTH CARE CENTRE IN NORTHERN INDIA.

Central Serous Chorioretinopathy(CSCR) is predominantly idiopathic and self limiting macular disease . Present study was planned to determine clinical prole and the factors contributing in nal visual outcome in CSCR.. Retrospective observational study was done on 65 eyes of 53 patients over a period of 2 years. Their best corrected visual acuity(BCVA), color vision, metamorphopsia and mean central macular thickness(CMT) at presentation were compared with values at 6 months follow-up. Mean age of patients was 38 years ± 5.43 years. 79.24% patients were males and 77.36% had unilateral involvement. 30.19% patients gave history suggestive of one or more potential risk factors. The mean BCVA improved from 20/80 at presentation to 20/20 and 20/25 in patients with isolated and CSCR with PED respectively at 6 months. The mean CMT reduced signicantly in both isolated CSCR and when associated with PED at 6 months. Color vision defects in 46(70.77%) eyes and metamorphopsia in 49(75.38%) eyes at presentation persisted in 7(10.7%) eyes and 20(30.76%)eyes respectively at 6 months. Final visual outcome signicantly correlated with visual acuity at presentation. CONCLUSION: BCVA at presentation strongly predicts nal visual prognosis. Patients need to be counselled regarding persistence of color vision decits and metamorphopsia.

Prevalence and predictors of colour vision defects among Egyptian university students

Background: Nowadays, widespread usage of colours increases the need for accurate estimation of colour vision defects and their effect on performing daily activities and study/work tasks. Aims: To determine the prevalence and predictors of colour vision defects among Assiut university students and to identify their relationship with self-reported visual function and perceived difficulties in performing daily activities. Methods: A cross-sectional study was conducted among 1426 students at Assiut University, Egypt. Data were collected by self-administered questionnaire consisting of: personal characteristics, prior awareness of colour vision defects, difficulties in daily colour vision activities, and visual function. Colour vision was assessed using Ishihara’s test of colour deficiency. Results: The prevalence of colour vision defects among students was 6.9% (red–green colour vision was 4.3% and total colour blindness was 2.6%). Students with colour vision defects had significantly higher odds ratios for difficulties in daily activities and study/work tasks related to colour perception. Students with colour vision defects had significantly lower mean values of general health, role difficulties, and colour vision scores compared to students with normal colour insight. Male sex and family history of colour vision defects were risk factors. Conclusions: A non-negligible percentage of Egyptian university students had colour vision defects, which had a negative impact on performing daily activities, executing study/work tasks, and choice of study/work specialties. Colour vision defects affected quality of life with regard to general health, role difficulties and colour vision. Male sex and family history of colour vision defects are nonmodifiable risk factors. This emphasizes the need for genetic counselling, especially in consanguineous marriage.