Tilted disc syndrome and colour vision

We assessed the anatomical variations of the globe and optic nerve in tilted disk (TD) syndrome using magnetic resonance imaging (MRI) findings and compared them with a control group. Eleven patients diagnosed with TD syndrome during eye examination were referred for MRI of the sella and chiasm to exclude intracranial mass lesions. The shape of the globe, the chiasmal angle, the insertion angles of the optic nerve in axial and parasagittal planes determined by lines parallel to the optic nerve and tangent to the globe in TD syndrome were compared with a control group consisting of 53 cases. Gender ratios were 7/4 (F/M) for the TD group and 35/18 for the control group (p>0.05). The insertion angle of the optic disk to the globe was wider in the temporal quadrant (p<0.05) and narrower in the nasal quadrant (p<0.05) in TD syndrome than in the control group. There was no significant difference in the superior and inferior insertion angles between the groups. The anterior-posterior (AP) diameter of the globe was significantly longer in patients with TD (p<0.05). There was no significant difference between the optic chiasm angles. The relationships of the optic disk and the globe were significantly different in patients with TD syndrome in comparison to the control group. TD syndrome is related to the malalignment of optic nerve and globe in the horizontal plane.

PURPOSE:To estimate the magnitude and determinants of color vision defects (CVD) among preparatory health science students.METHODS:A cross-sectional survey was conducted in 2017. Participants were assessed using 24-plate Ishihara's Test of Color Vision chart. If ≤9 plates were read correctly, the color vision was regarded as deficient. The CVD prevalence and its 95% confidence interval (CI) were calculated. CVD was associated with gender, family history of CVD, and other vision problems.RESULTS:We evaluated 1126 students (552, 49% males; mean age: 18.7 ± 0.7 years). The prevalence of CVD was 1.77% (95% CI: 1.0, 2.6). Among male students, it was 3.5% (95% CI: 1.9, 5.0). Only one female student had CVD. The Duran CVD was found in 18 (1.6%) students. However, only two students had Tritan CVD. Three among twenty CVD students knew that they suffer from CVD. CVD was positively associated to a family history of CVD (odds ratio [OR] = 3.8; 95% CI: 1.4, 10.1;P = 0.02) and male gender (OR = 20.4 [95% CI: 2.7, 153]). CVD was not significantly associated to other vision problems (OR = 0.8 [95% CI: 0.3, 2.0]).CONCLUSION:Eighteen in thousand health sciences students suffered from CVD. Ten percent of them had Tritan CVD. Duran CVD seems to be a male sex-related and/or a familial condition. Most of the CVD students seem to have adopted to this defect and were not aware of suffering from it. Screening for CVD is therefore debatable.

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. 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. 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. 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. 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.

The spectrum of the visual field defects in the tilted disc syndrome Clinical study and review

Impact of visual function on computer task accuracy and reaction time in a cohort of patients with age-related macular degeneration

Objectives: We have treated people who have color vision defects with oriental medicine; here we demonstrate several representative cases to illustrate the effectiveness of our treatment. Material and methods: We recruited study patients who visited one oriental hospital for color vision defects. We show several representative cases to illustrate the effectiveness of our treatment. The study initially consisted of 178 subjects who took part during a 3-year period. Subjects, all of whom consented to this treatment and trial, were classified by those who have a color vision defect and those who dont by the Ishihara test and another by the Hahn color vision test. We tried color vision correction treatment with acupuncture. Acupuncture therapy where the retina and optic nerves were activated was conducted in parallel with vision correction. Assessment of therapy was conducted at 30 times, 60 times, 90 times, or 120 times of therapy. Results: Assessment of therapy was performed by conducting treatment 30 times, 60 times, 90 times, or 120 times. Surprisingly, all subjects could correctly recognize color after the treatment; although there were case by case differences according to the number of therapy treatments each individual received. Conclusions: Color vision defects can be treated. To enable those with color vision defects to enjoy better quality of life and increased opportunity in color vision-dependent job fields, therapy to correct the problem is a viable option.

Introduction: Colour vision deficiency is a common but unnoticed condition. Medical students must be aware of their congenital colour vision deficiency and its effects on their work, so that color vision deficient student may not choose the discipline such as pathology and radiology, where colour vision is very important. Methods: This is a cross-sectional study conducted in the Department of Clinical Physiology, Maharajgunj Medical Campus, Institute of Medicine, Kathmandu from February 2013 to January 2016. Total of 556 medical and nursing students selected by convenient sampling, underwent color vision evaluation by using Ishihara chart. Results: Out of 302 male students, 20 (6.6%) were color vision deficient. Similarly, out of 254 female students, two (0.8%) were colour vision deficient. Among the male students, two (10%) were total colour blind, eight (40%) were suffering from deuteranomaly and 10 (50%) were suffering from deuteranopia. Colour vision deficiencies were observed more in Chhetri (9.5%), followed by Brahmin (7.1%) and Madhesi ethnicity (6.9%). Conclusion: The prevalence of colour vision deficiency in Nepalese medical students is significant. Therefore, they should be screened for colour vision deficiency, so that the students with colour vision defect can choose appropriate discipline as their future carrier where colour vision defect may not affect their work.

Numerical Confusion Errors in Ishihara Testing: Findings From a Population-based Study

One of the most common inherited vision disorders is congenital color vision deficiency (CVD). Its prevalence in men can be as high as 8% and 0.5% in women.[1] Men are predominately affected by the X-linked inheritance pattern, while women become carriers of the abnormal gene.[2] There are also different causes for acquired color vision defects, such as ocular or neurological disease, some metabolic disorders, drug toxicity and exposure to certain solvents.[3] Congenital CVD results from genetic mutations that affect the expression of the full complement of normal cone photoreceptors. They’re divided into three categories based on their intensity (anomalous trichromacy, dichromacy, and monochromacy). CVD places the sufferer at a distinct disadvantage when performing certain visual tasks—in particular those tasks in which a colored target is embedded in a variegated background of a different color. CVD affects many areas of life, and its adverse impact is experienced at all stages, i.e., from childhood to adolescence and adulthood.[45] Population is one of the biggest problems in India and the reason for so many compromises starting from lack of resources at every level. Healthcare is just one example. When providing even simple vision assessment in school children becomes a big task few tests like color vision examination is rarely being performed. Population diagnosis is usually late at the time of medical examination at the time of higher education or specific job. They are rarely diagnosed early in life. Late diagnosis leads to rejection for a particular job most of the time which has a psychological impact on individuals. In India where an education system doesn’t give a student to choose multiple streams, it turns out, several professional choices can be negatively impacted by a color blindness diagnosis. CVD is a hidden disability because, though present from birth, its role comes to play only when children begin to attend regular schools to learn some tasks.[6] From here onwards process of considerable difficulties in learning starts. Children with CVD are frequently marked as lethargic students, which could mentally affect them, or could evoke negative responses from instructors and guardian. This can lead to not only problems in learning but also in playing and in their social bonding. Various studies have been carried out all over the world to see the prevalence of CVD among school children.[789] Xie JZ, et al.[10] suggested that successful CVD testing can be done starting at age four. Cole stressed that school children should know if they have CVD so they can be helped more quickly to find adaptive strategies and be able to take it into account when planning their career.[11] Largest study on CVD in children is conducted to see the burden of this disability in India.[12] Authors have used Dalton’s psuedoisochromatic plates for color vision screening. It is based on Ishihara color vision chart principle. The Dalton screener consists of 6 sets with 4 plates in each that includes one demo plate and three screening plates. Those, who failed to read three or more plates in two or more random sets of the Dalton’s pseudoisochromatic plate were considered to have CVD after confirming with Ishihara’s PIP color vision testing (38 plate edition). The result shows CVD among boys was found to be 2.76%. Children from urban region (3.17%) were more likely to be color vision deficient than children from rural region (1.79%). These results are similar to the other parts of the country and few other countries from Asia. Screening of CVD is relatively easy does not require any formal training and can be performed by any assigned staff. Various plate tests are available, such as Ishihara, Tokyo, HRR plate test, which are highly sensitive and specific to detect CVD. Because of rapidly evolving technologies with more and more use of color coded tasks in each sector including education sector and specific job requiring color differentiation, the efforts should be made at a fundamental level in screening of color vision defects during comprehensive school eye health programs. Since CVD is congenital and there is no permanent cure for it. However, advice at an early age could help to find adaptive strategies, which enable them to avoid disappointments in the choice of their future career. Parental education, awareness, genetic counseling strategies in the regions with high CVD incidence could help a lot in minimizing the occurrence of the disorder among their offspring.

The evaluation of colour vision and discrimination of an individual forms an integral part of a routine eye and vision examination. With the increasing prevalence of inherited colour vision deficiencies, defects of colour vision can be detected in an optometric practice by means of a variety of tests available. The present article comprises an overview of the design and function of a selection of colour vision tests that are administered manually and, in some cases, have been modified to form a computerised version.

BackgroundTo evaluate the angle kappa and pupil barycentre configuration in patients with myopic tilted disc syndrome (TDS).MethodsThirty‐five eyes of 35 patients with TDS were included in the study. Thirty‐five eyes of 35 age‐ and sex‐matched healthy subjects were enrolled in the control group. All measurements were performed with the Lenstar LS 900. Angle kappa was calculated according to Pythagorean theorem using the x and y co‐ordinates of the pupil centre. Pupil dx and pupil dy values (pupil dx: x co‐ordinate of pupil centre relative to corneal apex, pupil dy: y co‐ordinate of pupil centre relative to corneal apex) were used to evaluate the pupil barycentre configuration. Central corneal thickness, white to white (cornea diameter), pupil diameter, anterior chamber depth, lens thickness, and axial length were also measured.ResultsThe calculated mean angle kappa distance was 0.27 ± 0.15-mm in the TDS group and 0.29 ± 0.23-mm in the control group (p = 0.42). The mean pupil dx was −0.01 ± 0.24-mm in the TDS group and −0.17 ± 0.14-mm in the control group (p = 0.006). The mean pupil dy was −0.02 ± 0.13-mm in the TDS group and −0.05 ± 0.22-mm in the control group (p = 0.65).ConclusionsThe pupil barycentre in TDS cases was statistically significantly closer to the corneal vertex on the horizontal plane compared to the control group. However, there was no statistically significant differences in terms of angle kappa and pupil dy values between the groups. According to our results, refractive surgery can be performed safely with respect to complications related to decentration of ablation zone and decentration of multifocal intraocular lenses in these groups of patients.

In retinitis pigmentosa patients the effect of cystoid macular edema on colour vision was studied. The occurrence of cystoid macular edema decreases with increasing colour vision defect. The mutual proportion of the main types of colour vision defects remains stable until visual acuity has dropped to 0.5; at lower VA levels the number of red-green defects increases. Neither the finding of a blue-yellow colour vision defect in FM100 Hue testing nor the appearance of anomaloscopic pseudoprotanomaly is influenced by cystoid macular edema. The authors conclude that cystoid macular edema in retinitis pigmentosa patients mainly affects visual acuity and not colour vision. They also noted a familial occurrence of cystoid macular edema.

PurposeTo study deep optic nerve head (ONH) morphology in tilted disc syndrome (TDS) and identify factors associated with retinal nerve fiber layer (RNFL) defect.MethodsIn patients with TDS, we evaluated the optic disc shape using the Bruch's membrane opening (BMO)–anterior scleral canal opening (ASCO) offset and measured the border tissue (BT) length, depth, and angle in the direction of the tilt, using radial ONH optical coherence tomography (OCT). We compared the parameters between the TDS groups with and without RNFL defects.ResultsTwenty-one eyes had no glaucomatous RNFL defect, and 38 eyes had a glaucomatous RNFL defect. The group with RNFL defects had a higher baseline IOP, larger tilt axis of BMO-ASCO optic disc margin (76.4° ± 14.5° vs. 87.9° ± 15.4°, P = 0.012), larger BMO–lamina cribrosa insertion (LCI) angle (25.6° ± 9.3° vs. 43.6° ± 15.2°, P < 0.001), and more lamina cribrosa (LC) defects (4.3% vs. 30.6%, P = 0.028) than without RNFL defects. The tilt axis and BMO-LCI angle were significant factors after adjusting for baseline IOP and LC defect. The BMO-LCI angle had excellent diagnostic power for glaucomatous RNFL defect in TDS, similar to the visual field mean deviation.ConclusionsOCT-based large deep ONH BT angle and tilt axis were factors associated with the presence of RNFL defects in TDS. The results suggest a mechanism of RNFL defect associated with structural ONH deformation. Further investigations are warranted to understand the role of ONH structures in a general population with and without optic disc tilt.

Aim: To assess the changes in color vision in diabetic patients in different stages of diabetic retinopathy compared to healthy individuals. MATERIALS AND METHODS: This cross-sectional comparative study included sixty-eight eyes of 40 diabetic patients, divided into four subgroups (10 patients / group) at different stages of diabetic retinopathy (Eighteen of them had maculopathy) as well as 20 eyes of 10 healthy individuals as controls. Diabetic retinopathy and maculopathy were assessed clinically by direct and indirect fundus examination along with fluorescein fundus angiography, optical coherence tomography. Color vision was assessed quantitatively by Ishihara pseudo iso-chromatic plates test and qualitatively by Farnsworth D-15 test. Results: Only two control eyes (10%) failed the Ishihara pseudo iso-chromatic plates test, compared to 19 diabetic eyes (27.9%), 14 eyes (20.58%) were suspects. Also just two control eyes (10%) failed the Farnsworth d-15 test while 34 (50%) diabetic eyes failed the test showing; with Tritanopia was the most encountered color vision defect. We find that color vision defects also increases with increasing disease duration, severity of diabetic retinopathy, increased macular thickness and presence of maculopathy, while type of diabetes shows no significant effect. Conclusion: Diabetes mellitus has a clear negative effect upon the color vision in both qualitative and quantitative manner leading to loss of color vision perception with a varying degree in relation to the type of diabetes, degree of retinopathy, the duration of illness, presence of maculopathy and the increased macular thickness when compared to normal healthy individuals.

1 - Colour vision: theories and principles