A Novel Splice-Site Variant in CACNA1F Causes a Phenotype Synonymous with Åland Island Eye Disease and Incomplete Congenital Stationary Night Blindness

Background: CACNA1F-related disorders encompass progressive and non-progressive disorders, including Åland island eye disease and incomplete congenital stationary night blindness. These two X-linked disorders are characterized by nystagmus, color vision defect, myopia, and electroretinography (ERG) abnormalities. Ocular hypopigmentation and iris transillumination are reported only in patients with Åland island eye disease. Around 260 variants were reported to be associated with these two non-progressive disorders, with 19 specific to Åland island eye disease and 14 associated with both Åland island eye disease and incomplete congenital stationary night blindness. CACNA1F variants spread on the gene and further analysis are needed to reveal phenotype-genotype correlation. Case Report: A complete ocular exam and genetic testing were performed on a 13-year-old boy. A novel splice-site variant, c.4294-11C>G in intron 36 in CACNA1F, was identified at hemizygous state in the patient and at heterozygous state in his asymptomatic mother and explained the phenotype synonymous with Åland island eye disease and incomplete congenital stationary night blindness observed in the patient. Conclusion: We present a novel variant in the CACNA1F gene causing phenotypic and electrophysiologic findings indistinguishable from those of AIED/CSNB2A disease. This finding further expands the mutational spectrum and our knowledge of CACNA1F-related disease.

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.

Assessment of Color Vision Among School Children: A Comparative Study Between The Ishihara Test and The Farnsworth D-15 Test

Introduction: Color vision is one of the important attribute of visual perception. The study was conducted at different schools of Kathmandu to compare the findings of the Ishihara Pseudoisochromatic test and the Farnsworth D-15 test. Methods: A cross-sectional study was conducted among 2120 students of four schools of Kathmandu. Assessment included visual acuity measurement, slit lamp examination of anterior segment and fundus examination with direct ophthalmoscopy. Each student was assessed with the Ishihara pseudoisochromatic test and the Farnsworth D-15 test. The Chi-square test was performed to analyse color vision defect detected by the Ishihara test and the Farnsworth D-15 test. Results: A total of 2120 students comprising of 1114 males (52.5%) and 1006 females (47.5%) were recruited in the study with mean age of 12.2 years (SD 2.3 years). The prevalence of color vision defect as indicated by the Ishihara was 2.6 and as indicated by the D-15 test was 2.15 in males. Conclusions: For school color vision screening, the Ishihara color test and the Farnsworth D-15 test have equal capacity to detect congenital color vision defect and they complement each other. Keywords: color vision; children; defect; Farnsworth D-15; Ishihara.