Color Vision Research Articles

Asymmetric distribution of color-opponent response types across mouse visual cortex supports superior color vision in the sky.

Color is an important visual feature that informs behavior, and the retinal basis for color vision has been studied across various vertebrate species. While many studies have investigated how color information is processed in visual brain areas of primate species, we have limited understanding of how it is organized beyond the retina in other species, including most dichromatic mammals. In this study, we systematically characterized how color is represented in the primary visual cortex (V1) of mice. Using large-scale neuronal recordings and a luminance and color noise stimulus, we found that more than a third of neurons in mouse V1 are color-opponent in their receptive field center, while the receptive field surround predominantly captures luminance contrast. Furthermore, we found that color-opponency is especially pronounced in posterior V1 that encodes the sky, matching the statistics of natural scenes experienced by mice. Using unsupervised clustering, we demonstrate that the asymmetry in color representations across cortex can be explained by an uneven distribution of green-On/UV-Off color-opponent response types that are represented in the upper visual field. Finally, a simple model with natural scene-inspired parametric stimuli shows that green-On/UV-Off color-opponent response types may enhance the detection of "predatory"-like dark UV-objects in noisy daylight scenes. The results from this study highlight the relevance of color processing in the mouse visual system and contribute to our understanding of how color information is organized in the visual hierarchy across species.

Hue selectivity from recurrent circuitry in Drosophila

In the perception of color, wavelengths of light reflected off objects are transformed into the derived quantities of brightness, saturation and hue. Neurons responding selectively to hue have been reported in primate cortex, but it is unknown how their narrow tuning in color space is produced by upstream circuit mechanisms. We report the discovery of neurons in the Drosophila optic lobe with hue-selective properties, which enables circuit-level analysis of color processing. From our analysis of an electron microscopy volume of a whole Drosophila brain, we construct a connectomics-constrained circuit model that accounts for this hue selectivity. Our model predicts that recurrent connections in the circuit are critical for generating hue selectivity. Experiments using genetic manipulations to perturb recurrence in adult flies confirm this prediction. Our findings reveal a circuit basis for hue selectivity in color vision.

Information Transmission through Biotic-Abiotic Interfaces to Restore or Enhance Human Function.

Advancements in reliable information transfer across biotic-abiotic interfaces have enabled the restoration of lost human function. For example, communication between neuronal cells and electrical devices restores the ability to walk to a tetraplegic patient and vision to patients blinded by retinal disease. These impactful medical achievements are aided by tailored biotic-abiotic interfaces that maximize information transfer fidelity by considering the physical properties of the underlying biological and synthetic components. This Review develops a modular framework to define and describe the engineering of biotic and abiotic components as well as the design of interfaces to facilitate biotic-abiotic information transfer using light or electricity. Delineating the properties of the biotic, interface, and abiotic components that enable communication can serve as a guide for future research in this highly interdisciplinary field. Application of synthetic biology to engineer light-sensitive proteins has facilitated the control of neural signaling and the restoration of rudimentary vision after retinal blindness. Electrophysiological methodologies that use brain-computer interfaces and stimulating implants to bypass spinal column injuries have led to the rehabilitation of limb movement and walking ability. Cellular interfacing methodologies and on-chip learning capability have been made possible by organic transistors that mimic the information processing capacity of neurons. The collaboration of molecular biologists, material scientists, and electrical engineers in the emerging field of biotic-abiotic interfacing will lead to the development of prosthetics capable of responding to thought and experiencing touch sensation via direct integration into the human nervous system. Further interdisciplinary research will improve electrical and optical interfacing technologies for the restoration of vision, offering greater visual acuity and potentially color vision in the near future.

Posterior Cranial Fossa Surgery with a 3 Dimensional Exoscope: A Single-Center Survey-Based Analysis and a Literature Review

The potential advantages of exoscopy have been discussed theoretically for a long time. Such a concept holds significance, especially in the specific setting of the posterior cranial fossa (PCF), characterized by complex anatomy and long and narrow surgical corridors with relatively extreme working angles. We aimed to: 1) analyze the institutional preliminary case-based data on the use of the Robotic 3D Exoscope AEOS Aesculap in three different PCF approaches: retrosigmoid (RSA), midline suboccipital (MSA), and supracerebellar infratentorial via feedbacks was collected using a 20-point questionnaire, and 2) perform a comprehensive review of the literature concerning the use of EX in PCF surgery. A total of 38 patients with neurosurgical pathologies underwent a neurosurgical procedure using the EX (Robotic 3D exoscope AEOS Aesculap) at our institution between January and March 2022. 21 surgeons were involved in the abovementioned PCF surgeries and answered the questionnaire. The main perceived advantages were in terms of ergonomics (67%), magnification (52%), and visualization of extreme angles. The main reported disadvantage was color vision (16, 76%), followed by manual mobility (24%). Concerning the review, the search of the literature yielded a total of 177 results. Upon full-text review, 17 articles were included, including 153 patients. In conclusion, our study provides a comprehensive evaluation of the advantages and challenges associated with using the exoscope in posterior fossa surgery, setting a precedent as the first to report on a questionnaire-based analysis of exoscope utilization in this specific domain.

Enhancing statistical chart accessibility for people with low vision: insights from a user test

AbstractA remote user test was performed with two versions (one accessible and one non-accessible) of three types of web-based charts (horizontal bar chart, vertical stacked bar chart, and line chart). The objectives of the test were: (a) to validate a set of heuristic indicators for the evaluation of the accessibility of statistical charts presented in a previous work (Fariñas Falcón et al. in Mediocentro Electrónica 21(1):65–68, 2017); (b) to identify new barriers and preferences for users with low vision in the access and use of this content not previously contemplated. 12 users were tested, with a variety of conditions associated with low vision: low visual acuity (6 users), reduced central vision (2 users), reduced peripheral vision (2 users), blurry vision (1 user), sensitivity to light (3 users), Nystagmus (2 users) and color vision deficiency (CVD) (4 users). From a quantitative standpoint, accessible versions of charts were more efficient, effective, and satisfactory. From a qualitative point of view, results verify the relevance of heuristics H2, Legend; H3, Axes; H6, Data source (as data table); H10, Safe colors; H11, Contrast; H12, Legibility; H13, Image quality; H14, Resize; H16, Focus visible; H17, Independent navigation; related to the proposed tasks. As new observations, tooltips were highly valued by all users, but their implementation must be improved to avoid covering up significant parts of the charts when displayed. The data table has also been frequently used by all users, especially in the non-accessible versions, allowing them to carry out tasks more efficiently. The position and size of the legend can be a significant barrier if it is too small or appears in an unusual position. Finally, despite the limitations related to color perception, some users prefer color graphics to black and white, so, to target all profiles, it is necessary to redundantly encode categories with colors and patterns as well.

Outcome of pediatric cataract surgery including color vision, stereopsis, and cognition in a tertiary eye care center in India.

Pediatric cataract is an important cause of avoidable childhood blindness in India. Although there are studies on clinical features and visual acuity outcomes of pediatric cataract surgery, there are no studies that look into aspects of color vision, stereopsis, and cognitive functions in children with cataracts. Studying these parameters pre- and postsurgery will help us assess the overall components of visual function that are critical for the child's development. With this in mind, we aimed to study the clinical features, outcome of treatment, color vision, stereopsis, and cognitive functions in children with cataracts. Design: Hospital-based prospective descriptive study. Data of 68 children (0 < 18 years) were collected, on the clinical features, visual acuity, color vision, stereopsis, and social and intelligence quotient before and after surgery. Data analysis was performed using Graph Pad Prism software version 9.4.0 (673). Ninety eyes of 68 children (36-bilateral/32-unilateral) were operated. A total of 46 children were available at 6 months' follow-up (28 bilateral cataracts (46 eyes) and 18 unilateral cataracts). Nineteen (67.8%) of the bilateral, had a best corrected visual acuity of 6/6-6/18 in the better eye and nine (50%) of the unilateral had a visual acuity of 6/18-6/6 in the operated eye. Preoperatively, 61.5% of the children had a stereopsis of 100-600 arc-secs. Post-operatively, 84.4% of the children had a stereopsis in the range <50-600 arc-secs. All children had color vision deficiency. Preoperatively, 62% of the children had strong and moderate deficiency, whereas postoperatively, 66.6% had mild deficiency. We found negative correlation (r = -0.503) between social quotient and percentage of visual impairment indicating that when visual impairment increases social quotient decreases. The mean IQ preoperatively was 94.36 ± 2.98 and postoperatively 101.38 ± 2.77, with 95% confidence interval P value was statistically significant (P = 0.0001). This shows better and faster performance postoperatively. Majority of the children had improved visual acuity after surgery. This outcome can be extrapolated to the overall improvement in stereopsis, color vision, and higher cognitive functions.

Ocular toxicity of daily anti-tubercular treatment regimen: A prospective observational study

Context: India carries a significant burden of TB which is the commonest cause of infectious disease-related mortality. Anti-tubercular drugs can cause serious ocular toxic effects. Optical coherence tomography (OCT) can be used as a valuable tool in the quantitative analysis of anti-tubercular treatment (ATT)-induced toxic optic neuropathy. Aims: To study the changes in visual parameters in patients on ATT and to analyze the OCT changes in patients by taking measurements once before initiation of treatment and once during ongoing treatment (between three and six months). Settings and Design: Tertiary care center, Prospective observational study. Methods and Material: A prospective observational study was conducted in 140 eyes of 70 subjects undergoing ATT as per the latest RNTCP guidelines where the following determinants were examined, and the corresponding values were taken once before initiation of treatment and once during ongoing treatment (between three and six months) and results were analyzed. Around 90% of the subjects were examined at the end fourth month. Visual acuity was taken using the Log Mar chart, color vision using Ishihara’s chart, and slit lamp examination and fundus evaluation using a 90 D lens. OCT was done and average nasal, temporal, superior, and inferior quadrant retinal nerve fiber layer (RNFL) measurements were taken. Perimetry was also done; however, findings were not included in this study. Statistical Analysis Used: Frequency and percentage were applied to study the changes in visual parameters in patients on ATT. A paired t-test was applied for numerical variables to analyze the OCT changes in patients undergoing ATT. A P value &lt; 0.05 was considered statistically significant. Results: Despite a near-normal appearance of the fundus on ophthalmoscopy, OCT clearly demonstrated and quantified the loss of retinal nerve fibers. Statistically significant RNFL thinning (P value &lt; 0.001) was noted in the superior, temporal, and inferior quadrants and least in the nasal quadrant (P = 0.005). Significant deterioration in visual acuity was observed following three months of ATT (P = 0.001). Red-green color vision abnormalities were detected in 14 out of 140 eyes (10%). Conclusions: RNFL thickness was reduced on OCT. RNFL thickness quantification and assessment of other visual parameters especially color vision help in the early diagnosis of ocular toxic effects of ATT. Hence, awareness and active screening are imperative in preventing visual impairment and blindness.

The Impact of Colour Vision Defect on Consumer’s Fruits Selection Process while Purchasing from Retail Fruit Shops in Bangladesh

Color Vision Defect affects about one in twelve males and two hundred women worldwide, according to research. CVD has a big impact in almost every marketing and branding circumstance, especially when product color is the key. This study began with a Red-Green CVD test of 522 Dhaka residents. Since few research have measured color blindness in Bangladesh, this study can be used as one of the Bangladesh color vision deficiency baseline results. The important factor of this study is whether this result is comparable to Bangladesh’s earlier result and whether Bangladesh has a lower/higher CVD prevalence than other nations. The most common CVD is Red-Green Colour Vision Defect. Green fruits turn yellow and red when maturing and CVD patients have trouble distinguishing neighboring colours like Red, Green, Brown, etc. After examining baskets of green and ripe yellow, red, and partly reddish fruits, this study evaluated the findings. This study found out that people with color vision defects had trouble choosing fruits from baskets. Furthermore, the study tested hypotheses to determine severity of Red-Green CVD and found out it to be less than expected probably due to coping mechanism, experience etc. in Red-Green CVD subjects.

COMPREHENSIVE COLOR VISION ENHANCEMENT FOR COLOR VISION DEFICIENCY: A TENSORFLOW AND KERAS BASED APPROACH

Individuals with color vision deficiency (CVD) often encounter challenges in navigating and interacting with their environment due to limitations in perceiving colors accurately. This deficiency can impede various daily tasks and activities, leading to dependency on others for assistance with color-related tasks and potentially limiting independence and inclusivity. Addressing these challenges, our research focuses on the development of a machine learning-based color transformation system. Leveraging TensorFlow and Keras frameworks, the system employs advanced machine learning techniques to identify and transform colors within images, ultimately enhancing visibility for individuals with CVD. The primary objective is to empower individuals with CVD by providing a real-world tool that improves color visibility in images and enables self-assessment of their condition. This solution aims to enhance navigation, reduce dependency on others for color-related tasks, and foster inclusivity through technological innovation. Additionally, our research emphasizes the accuracy and reliability of the machine learning models through rigorous testing and validation procedures, ensuring effectiveness across various scenarios and image types. An intuitive and user-friendly graphical user interface (GUI) is prioritized to cater to individuals with diverse technical abilities. Beyond its immediate impact, the research seeks to raise awareness and promote understanding of color vision deficiency within the broader community, ultimately contributing to a more equitable and accessible society for all.

A Rare Case Report of Bardet–Biedl Syndrome: A Syndrome of Pentad Symptoms

Bardet–Biedl syndrome (BBS) is a clinically and genetically heterogeneous disorder that manifests as a result of primary cilia impairment, characterized by retinitis pigmentosa, obesity, mental retardation, hypogonadism, and polydactyly. The five findings together are called “the pentad” and are found in most of the cases. This is the case of a 14-year-old boy, 2nd issue of consanguineous marriage of his parents, having a positive family history, who presented with progressive dimness of vision, learning disability, increased hunger, and weight since childhood. Initially, there were impaired night vision and peripheral vision problems, and later loss of color vision. He had no hearing problem, anosmia, cold intolerance, or steroid-taking history. His intranatal and postnatal history was uneventful except slightly delayed developmental milestone. His body mass index was 32.7 kg/m2, waist–hip ratio was 1.08, height was in the 50th centile on the growth chart. He had polydactyly, high-arched palate, acanthosis nigricans, and buried penis; testicular volume was prepubertal. Laboratory findings revealed high triglyceride, impaired glucose tolerance, hypogonadotropic hypogonadism, and grade-III fatty liver. He had bony spicule-like pigmentation in the periphery of both eyes suggestive of retinitis pigmentosa. Based on these data, BBS was diagnosed. In conclusion, BBS is a rare clinical syndrome that may go unnoticed by many clinicians. Renal failure is the leading cause of morbidity and mortality in patients with BBS. Therefore, early detection of BBS is vital to halt the progression of renal impairment.

Evaluation of the Efficacy of Enchroma Filters for Correcting Color Vision Impairment

Objective: This study examined the effectiveness of Enchroma Cx-14 filters on individuals with Red-Green color vision deficiency (CVD). Methods: ColorDx and the Farnsworth-Munsell (FM) 100-Hue test were used to assess subjective reactions to Enchroma. The ColorDx and FM, 100 Hue test error scores were computed and contrasted using Placebo (untinted glasses) and Enchroma CX-14, red, and green filters. Results: The findings demonstrated that while enchroma filters improved the mistake score in only two patients, they had no discernible impact on any CVD subject's performance. In one protan participant and all deutan individuals, colour discrimination was greatly enhanced by the red filter. Green filters and Enchroma did not raise mean error scores. Conclusion: Enchroma filters had limited effectiveness in improving color perception for individuals with Red-Green CVD.

Improving webtoon accessibility for color vision deficiency in South Korea using deep learning

Improving webtoon accessibility for color vision deficiency in South Korea using deep learning

Dynamic range issues and image information content when visualizing seismic data

The purpose of this review is to discuss the problem of seismic data visualization in relation to human vision capabilities based on the seismic signal dynamic range assessment. The ways of increasing the information content and efficiency of visualization methods in terms of increasing their resolution are considered. The conducted analysis has shown that the dynamic range of seismic recordings exceeds the capabilities of the human eye by 2–3 orders of magnitude and the capabilities of technical visualization means by 4–5 orders of magnitude. Color vision models are considered on example of the most versatile hardware additive RGB color model. The model was chosen based on the idea of the human vision system as a set of photosensitive cones that register red, green and blue colors and the human brain, which processes and forms a color image in one’s consciousness. The relationships between monochrome and color images perceived by the human eye based on several types of sensitive receptors have been established. It is concluded that the use of a color image significantly expands information capabilities. Thus, 8 grey steps are enough for the monochrome method of information output, whereas the use of color devices allows to increase the number of steps up to 14. The methodology for solving this problem consists in the application of new technologies based on the use of large-scale and three-dimensional images providing a significant increase in the values of luminous flux, resolution and contrast based on the expansion of the dynamic range taking into consideration the limits of human vision.

Assessment of visual and blood-related parameters among children with sickle cell anaemia at Murtala Muhammad Specialist Hospital in Kano, Nigeria.

Sickle cell disease (SCD) is a prevalent genetic disease worldwide and particularly in Nigeria. Retinopathy is a known complication of SCD, underscoring the need to assess visual parameters in children. This study aimed to evaluate the visual acuity (VA), color vision (CV), packed cell volume (PCV), and erythrocyte sedimentation rate (ESR) of Sickle cell anemic (SCA) patients attending the Sickle cell counseling unit of Murtala Muhammad Specialist Hospital (MMSH) in Kano. It was a descriptive cross-sectional study consisting of 60 participants, including 30 SCA patients and 30 healthy controls without systemic or ocular diseases, aged between 8 and 14 years. Visual acuity, CV, PCV, and ESR were assessed using Snellen Chart, Ishihara chart, Hematocrit test, and Westergren Method respectively. Data were analyzed using SPSS version 22.0. Statistical significance was set at P &lt; 0.05. Both SCA patients and controls demonstrated limited knowledge about VA, CV, and ESR tests, and a significant percentage had never undergone these tests. SCA patients exhibited mild to moderate visual impairment (VI) in both eyes, while controls had no VI. Abnormally low PCV and ESR values were observed in all SCA patients, whereas controls had normal values. Gender differences were observed in ESR levels, with females showing higher levels. Significant differences were found between controls and SCA patients in terms of VA, ESR, and PCV values. There was a general lack of awareness regarding the importance of VA and CV tests in the community. Visual impairment and abnormal PCV and ESR values were exclusive to the SCA patients, indicating their association with the disease.

Color discrimination repetition distorts color representations

Perceptual learning is the improvement of perceptual performance after repeated practice on a perceptual task. Studies on perceptual learning in color vision are limited. In this study, we measured the impact of color discrimination repetitions at a specific base color on color perception for entire hues. Participants performed five sessions of color discrimination training (200 or 300 trials per session) over five days, at colors on either the negative or positive direction of the L-M color axis, based on group assignment. We administered three color perception assessments (unique hues, color category boundaries, and color appearance) before and after the sessions to evaluate perceptual changes after training. The results showed declines in color discrimination thresholds after training, as expected. Additionally, the training influenced outcomes across all three assessment types. After the training, the perceived color appearance changed near the trained color along the stimulus hue, and some of the unique hues and the color category boundaries moved significantly toward the trained color. These findings indicate that short-term repetitions of color discrimination training can alter color representations in the visual system, distorting color perception around the trained color.

Chromatic vision and structural assessment in primary congenital glaucoma

Primary congenital glaucoma is a rare disease that occurs in early birth and can lead to low vision. Evaluating affected children is challenging and there is a lack of studies regarding color vision in pediatric glaucoma patients. This cross-sectional study included 21 eyes of 13 children with primary congenital glaucoma who were assessed using the Farnsworth D-15 test to evaluate color vision discrimination and by spectral domain optical coherence tomography to measure retinal fiber layer thickness. Age, visual acuity, cup-to-disc ratio and spherical equivalent data were also collected. Global and sectional circumpapillary and macular retinal fiber layer thicknesses were measured and compared based on color vision test performance. Four eyes (19%) failed the color vision test with diffuse dyschromatopsia patterns. Only age showed statistical significance in color vision test performance. Global and sectional circumpapillary and macular retinal fiber layer thicknesses were similar between the color test outcomes dyschromatopsia and normal. While the color vision test could play a role in assessing children with primary congenital glaucoma, further studies are needed to correlate it with damage to retinal fiber layer thickness.

E029 Intracranial haemorrhage in scleroderma renal crisis; an unusual presentation

Abstract Background/Aims Scleroderma renal crisis is a life-threatening complication of systemic sclerosis (SSc), which typically occurs in the first 5 years after disease onset. Several risk factors for development of renal crisis are well recognised, including diffuse skin involvement, presence of RNA polymerase 3 antibodies and preceding use of corticosteroids. Methods A 66 year old female 6 years post diagnosis of stable diffuse systemic sclerosis/ polymyositis overlap (PM Scl 100 positive) presented to her GP with a 1 week history of fatigue. She had been seen 2 months earlier by her rheumatologist with stable, mild skin involvement. She had no preceding history of hypertension or other significant co-morbidity. A month earlier she received antibiotics for a chest infection from which she made a slow but complete recovery. She was found to have shingles and started a course of oral acyclovir. Blood tests revealed acute kidney injury stage 3 (eGFR 10 from baseline 70). However, she deteriorated overnight, waking with headache and disturbed colour vision. This quickly deteriorated to bilateral blindness precipitating admission to the emergency department (ED). On arrival she was conscious but severely hypertensive with a BP of 240/105. She received ramipril, amlodipine and a GTN infusion with limited efficacy. CT head (CTH) showed a left occipitoparietal bleed. She then experienced a seizure in ED, which was terminated with lorazepam. She was intubated in the post ictal phase. Repeat CTH following the seizure showed a right frontal bleed extending into the subarachnoid space. Repeat CTH at 48 hours showed progression of the right frontal and left parieto-occipital intracerebral haemorrhages, with evidence of posterior reversible encephalopathy syndrome. Lumbar puncture was normal (VZV negative). Treatment was commenced with intravenous hydralazine. On day 2 of admission she required haemofiltration and subsequently regular renal dialysis. Results SSc was diagnosed in 2016, since when her main issue had been severe Raynaud’s phenomenon for which she took sildenafil. Her muscle disease had only ever manifested as a modestly raised CPK, which settled with a brief course of low dose prednisolone at diagnosis. She has never required DMARDs. She had mild reflux symptoms. Skin tightening was noted distally over her fingers, forearms, lower legs and feet. Annual echocardiography showed nothing to suggest developing pulmonary arterial hypertension. With supportive management she has made a remarkable neurological recovery and has returned to her pre-morbid level of function. She remains dialysis dependent at 4 months. Conclusion This lady lacked a single recognised risk factor for developing a renal crisis, and this occurred quite unexpectedly following a reassuring clinic visit just 2 months prior to presentation. As rheumatologists we must remain vigilant for features of a renal crisis and avoid being falsely reassured by a low risk profile. Disclosure L. Parker: None. N. Buchanan: None. E.L. Williams: None.

The construction of genetics teaching resources related to colour blindness and their application in genetics teaching.

Red-green colour blindness is a classic example for the teaching of X-linked recessive inheritance in genetics course. However, there are lots of types of color vision deficiencies besides red-green colour blindness. Different color vision deficiencies caused by different genes may have different modes of inheritance. In recent years, many research achievements on colour blindness have been made. These achievements could be used as teaching resources in genetics course. Here, we summarize the construction of genetics teaching resources related to colour blindness and their application in genetics teaching in several chapters such as introduction, cellular and molecular basis of genetics, sex-linked inheritance, chromosomal aberration, gene mutation and advances in genetics. Teacher could use the resources in class or after class with different teaching methods such as questioning teaching method and task method. It may expand students' academic horizons and inspire students' interest in genetics besides grasping basic genetic knowledge.

Evaluating the level of visual acuity to minimise false-positives in different colour vision tests

ABSTRACT Clinical relevance Accurate colour vision assessment is important in clinical settings to minimise false-positive errors and enhance the reliability of diagnoses outcomes. Background Colour vision testing is valuable in assessing the visual system, particularly given the high proportion of individuals with poor vision. This study aimed to determine the minimum visual acuity level required to perform a colour-vision test without errors. Methods After fogging the right eyes of 52 healthy participants using plus lenses to 1.60 logMAR, vision was evaluated using Ishihara, Hardy – Rand – Rittler Standard Isochromatic, Waggoner Pseudo-isochromatic, City University, Waggoner Computerised, and Farnsworth D-15 tests. Participants then completed these tests at lower fogging degrees (in 0.1-logMAR intervals). The acuity at which 5% of the tested population was considered abnormal was determined. Results Significant differences were found in the average visual acuity required to perform colour vision tests without errors (p < 0.05). The Waggoner Computerized test required the highest average visual acuity among the tests utilised. The Farnsworth D-15 test yielded the highest logMAR values. No significant differences were observed between the Waggoner Pseudo-isochromatic test and Hardy – Rand – Rittler Standard Isochromatic, Ishihara, and Farnsworth D-15 tests (p > 0.05). Additionally, no significant differences were found between the Ishihara and Hardy – Rand – Rittler tests (p > 0.1) or between the Waggoner Computerized and City University tests (p = 0.11). Colour vision testing maintained an accuracy ≤ 1.0 logMAR with the Ishihara and Hardy – Rand – Rittler tests, 1.1 logMAR with the Waggoner Pseudo-isochromatic and Farnsworth D-15 tests, and 0.9 logMAR with the Waggoner Computerized and City University tests. Conclusions Insights are provided into the visual acuity thresholds required for accurate colour vision testing, which can serve as a basis for future research and provide a reference for clinical practice in this field.

Relationship of skin complexion with gingival tissue color and hyperpigmentation. A multi-ethnic comparative study

Background and ObjectiveThe most frequently seen intra-oral soft tissue is the gingiva. Most often, it is seen as coral-pink tissue that surrounds the neck of the teeth. Gingiva that encircles the tooth necks and covers the alveolar processes of the jaws is an intra-oral tissue that exhibits biomimetic features. The wide range of colors of the gingiva depends on the configuration of gingival vascularity, the degree of epithelial cornification, level of melanogenesis, and the depth of epithelialization. However, the color of the gingiva varies depending on the degree of melanin pigmentation. The current study aimed to identify the different distribution patterns of gingival color and determine the correlation between skin color, gender, and geographical area of origin.Materials and methodsA total of 839 subjects were involved in the study where the gingival color and skin tone were measured using the Dummett-Gupta Oral pigmentation Index (DOPI) combined with VITA VMK MASTER and skin shade method developed by Revlon (USA) and L’Oreal (France) for makeup foundation shades. One investigator was calibrated for the examination of the colors after being tested for normal color vision and color aptitude using the line test.ResultsA significant association was found between skin color and gingival pigmentation (χ2 value (6) = 114.48; P = 0.001). It was also found that females (67.1%) significantly had darker gingiva than males (58.3%). The study statistics display that location of the individual was also statistically associated with melanin pigmentation of the gingiva (χ2 value (57) = 559.33; P = 0.001).ConclusionThe study concluded that gender, skin color, and individual location are significantly associated with gingival melanin pigmentation.