Color Vision Research Articles

Detecting a Stalker: The Effect of Body Posture, Gaze Direction, and Camouflage Pattern on Predator Detection

ABSTRACTThe success of a predatory attack is related to how much a predator manages to approach a prey without being detected. Some carnivore mammals use environmental objects (e.g., leaves and branches) as visual obstacles during stalking behavior, allowing them to expose only parts of their bodies while approaching and visual monitoring their prey. Here, we investigate the influence of carnivores’ body postures, gaze direction, and camouflage pattern on their detection by prey. To do so, we photographed taxidermized carnivore models (cougar, ocelot, and lesser grison) in their preserved natural habitats and presented these images to human dichromats (i.e., colourblinds) and trichromats (i.e., normal color vision). Our findings highlight the importance of body outline and gaze as search images during predator detection tasks. We also demonstrate that coat and facial color patterns can camouflage predator's body outline and gaze. This is the first behavioral evidence that the facial coloration of natural predators might mask their gaze to potential prey. Furthermore, we observed that carnivore coat color patterns may serve as an additional cue for trichromats, particularly in hidden carnivore detection tasks that proved to be more challenging for dichromats. Our results show possible strategies that evolved between predator and preys, in which prey make use of body outlines, gaze direction, and coat color to improve predator detection, while predators potentially evolved stalking behavior and body/gaze camouflage as counter strategies to cope with the improvements in prey's perception and conceal their presence.

BerryPortraits: Phenotyping Of Ripening Traits cranberry (Vaccinium macrocarpon Ait.) with YOLOv8.

BerryPortraits (Phenotyping of Ripening Traits) is open source Python-based image-analysis software that rapidly detects and segments berriesand extracts morphometric data on fruit quality traits such as berry color, size, shape, and uniformity. Utilizing the YOLOv8 framework and community-developed, actively-maintained Python libraries such as OpenCV, BerryPortraits software was trained on 512 postharvest images (taken under controlled lighting conditions) of phenotypically diverse cranberry populations (Vaccinium macrocarpon Ait.) from the two largest public cranberry breeding programs in the U.S. The implementation of CIELAB, an intuitive and perceptually uniform color space, enables differentiation between berry color and berry brightness, which are confounded in classic RGB color channel measurements. Furthermore, computer vision enables precise and quantifiable color phenotyping, thus facilitating inclusion of researchers and data analysts with color vision deficiency. BerryPortraits is a phenotyping tool for researchers in plant breeding, plant genetics, horticulture, food science, plant physiology, plant pathology, and related fields. BerryPortraits has strong potential applications for other specialty crops such as blueberry, lingonberry, caneberry, grape, and more. As an open source phenotyping tool based on widely-used python libraries, BerryPortraits allows anyone to use, fork, modify, optimize, and embed this software into other tools or pipelines.

Response of Patients with Color Vision Defects to Worth 4-Dot and Duochrome Tests

Background: Individuals with congenital color vision defects (CVDs) are at greater risk of misidentifying colors, necessitating an investigation into their ability to distinguish colors accurately. This study aimed to assess how individuals with CVDs perceive the colors in the Worth four-dot (W4D) and duochrome tests. It also explored whether individuals with CVDs require more detailed instructions from optometrists and eye care providers during these tests. Method: Thirty-two participants with congenital CVDs were recruited for this study. Participants with ocular diseases were excluded based on a brief questionnaire. The participants underwent a W4D test to determine the colors of four circles and the duochrome test without using filters. Result: All the participants correctly identified the W4D colors, except for five participants (15.62%). Furthermore, among all the participants, two (one with deuteranopia and one with protanopia) failed to identify the colors correctly in the duochrome test (6.25%). Conclusions: The findings suggest that in the context of optometric assessment, it could be essential for optometrists to incorporate a preliminary inquiry into a patient’s ability to identify colors prior to performing diagnostic tests such as the W4D or duochrome tests. Incorrect responses from patients with CVDs might mislead optometrists regarding the proper outcomes of the test.

Colour vision deficiency is associated with increased prevalence of amblyopia, strabismus and ametropia: a large population study

AimsTo examine the association between colour vision deficiency (CVD) and other ophthalmic disorders including amblyopia, strabismus and ametropia in a large population study.MethodsThe retrospective, cross-sectional study included 916 388 Israeli...

Color Models in the Process of 3D Digitization of an Artwork for Presentation in a VR Environment of an Art Gallery

This study deals with the color reproduction of a work of art to digitize it into a 3D realistic model. The experiment aims to digitize a work of art for application in a virtual reality environment concerning faithful color reproduction. Photogrammetry and scanning with a LiDAR sensor are used to compare the methods and work with colors during the reconstruction of the 3D model. An innovative tablet with a camera and LiDAR sensor is used for both methods. At the same time, current findings from the field of color vision and colorimetry are applied to 3D reconstruction. The experiment focuses on working with the RGB and L*a*b* color models and, simultaneously, on the sRGB, CIE XYZ, and Rec.2020(HDR) color spaces for transforming colors into a virtual environment. For this purpose, the color is defined in the Hex Color Value format. This experiment is a starting point for further research on color reproduction in the digital environment. This study represents a partial contribution to the much-discussed area of forgeries of works of art in current trends in forensics and forgery.

Lack of retinal degeneration in a Dram2 knockout mouse model

Damage-regulated autophagy modulator 2 (DRAM2) is a homologue of the DRAM family protein, which can induce autophagy process. In the retina, DRAM2 is located to the inner segment of photoreceptors, the apical surface of retinal pigment epithelial (RPE) cells, and the lysosome. Pathogenic variants of DRAM2 lead to autosomal recessive Cone-rod dystrophy 21 (CORD21). Cone-rod dystrophy is characterised by primary cone involvement, or sometimes simultaneous cone and rod loss, thus leading to decreased visual acuity, colour vision deficits, photophobia, and decreased sensitivity of the central visual field. However, the mechanisms underlying DRAM2 related retinal diseases remained unclear. To further explore the role of Dram2 in the retina, we generated Dram2 knockout mice (KO) by CRISPR/Cas-9 technology and demonstrated that expression of DRAM2 was abolished in KO retinas. Dram2 ablation failed to manifest any retinal degenerative phenotypes. Dram2 KO did not exhibit visible defect in photo response and the overt structure of the retinas. Immunostaing analysis using antibodies against cone opsins revealed no detectable loss of cone cells. Moreover, no visible change was observed in the expression and localisation of rhodopsin and other membrane disc proteins in Dram2 KO retinas and no gliosis and apoptosis were detected in KO mice. In summary, these data revealed lack of overt retinal degeneration in Dram2 KO model and emphasized the importance of further investigation of the mechanisms underlying Cone-rod dystrophy 21.

Investigating the effects of simulated high altitude on colour discrimination

PurposeTo quantify changes in colour vision immediately after exposure to different altitudes of low-pressure hypoxia.MethodsThe study involved 35 healthy participants (ages 20–26). Colour vision was assessed using the Farnsworth-Munsell 100-Hue...

Correcting images for individual differences in color appearance

AbstractIndividual differences are a prominent feature of normal color vision and range from variations in sensitivity to perception and color naming. Corrections for differences in spectral sensitivity are common, and there is growing interest in calibrating displays for the sensitivity of an individual observer. In contrast, few studies have explored calibrations for aspects of color appearance. We developed a technique for adjusting images based directly on an individual's hue percepts and illustrate the principle of the approach using a set of hue scaling functions measured previously for a large sample of color‐normal observers (Emery et al. PNAS 2023). Colors in an image are mapped onto the average scaling function to define the hue perceived by the average “standard observer.” This hue is then mapped back to the chromaticity that would elicit the same response in any individual observer. With this correction, different observers – each looking at physically different images calibrated for their own hue percepts – should in principle agree on the perceived colors. Adjustments of this kind could be easily implemented on standard displays, because they require only measures of hue percepts and not spectral sensitivity, and could lead to greater consistency in the perception and communication about color across individuals with potentially widely different perceptual experiences of color.

Increasing intensity directly increases the perceived warmth of primary colors.

There is a long history of linking the perceptions of temperature and color (the "Hue-heat hypothesis"): red (R) and yellow (Y) are often considered warm, whereas blue (B) and green (G) are cool. Past studies, however, have largely used relatively broad-band light at a fixed intensity to test these relations. We tested whether increasing the intensity of highly saturated primary colors would lead to a concomitant change in the perceived temperature of those colors. 20 young healthy participants (M = 24.80±3.53 years; 45% female; 5% Hispanic; 45% non-White) with normal color vision were tested. An optical system with a Xenon-arc light source, chromatic filters (peak l = 465, 530, 572, 652nm), and a circular neutral density wedge to vary intensity were used (5 intensity levels). Temperature perception was assessed using an ordinal scale from - 5 (coolest) to + 5 (warmest). The order of the colors used and the intensity levels were varied randomly. Considering the average across intensity levels, B (-1.87) and G (+ 1.09) were considered the coolest, whereas Y (+ 2.1) and R (+ 3.75) were considered the warmest colors. All colors, however, warmed with increasing intensity. A linear regression fit to the averaged data across luminance explained the majority of the variance: B (r2 = 0.78), Y (r2 = 0.93), G (r2 = 0.98), and R (r2 = 0.92). Consistent with past data, our results show that color is significantly linked with temperature perception. Increasing the luminance of colors, however, strongly shifts the perception toward increased warmth.

Retinal Damage and Visual Network Reconfiguration Defines Visual Function Recovery in Optic Neuritis.

Recovery of vision after acute optic neuritis (AON) is critical to improving the quality of life of people with demyelinating diseases. The objective of the study was to prospectively assess the changes in visual acuity, retinal layer thickness, and cortical visual network in patients with AON to identify the predictors of permanent visual disability. We studied a prospective cohort of 88 consecutive patients with AON with 6-month follow-up using high and low-contrast (2.5%) visual acuity, color vision, retinal thickness from optical coherence tomography, latencies and amplitudes of multifocal visual evoked potentials, mean deviation of visual fields, and diffusion-based structural (n = 53) and functional (n = 19) brain MRI to analyze the cortical visual network. The primary outcome was 2.5% low-contrast vision, and data were analyzed with mixed-effects and multivariate regression models. We found that after 6 months, low-contrast vision and quality of vision remained moderately impaired. The thickness of the ganglion cell layer at baseline was a predictor of low-contrast vision 6 months later (ß = 0.49 [CI 0.11-0.88], p = 0.012). The structural cortical visual network at baseline predicted low-contrast vision, the best predictors being the betweenness of the right parahippocampal cortex (ß = -036 [CI -0.66 to 0.06], p = 0.021), the node strength of the right V3 (ß = 1.72 [CI 0.29-3.15], p = 0.02), and the clustering coefficient of the left intraparietal sulcus (ß = 57.8 [CI 12.3-103.4], p = 0.015). The functional cortical visual network at baseline also predicted low-contrast vision, the best predictors being the betweenness of the left ventral occipital cortex (ß = 8.6 [CI: 4.03-13.3], p = 0.009), the node strength of the right intraparietal sulcus (ß = -2.79 [CI: -5.1-0.4], p = 0.03), and the clustering coefficient of the left superior parietal lobule (ß = 501.5 [CI 50.8-952.2], p = 0.03). The assessment of the visual pathway at baseline predicts permanent vision disability after AON, indicating that damage is produced early after disease onset and that it can be used for defining vision impairment and guiding therapy.

Towers of Kuwait Arabic Neurocognitive Assessment: A novel executive and visuospatial functions assessment tool added to the CERAD neuropsychological battery-Arabic version (CERAD-ArNB)

Assessment of executive and visuospatial neurocognitive domains is lacking in the Omani population, especially for elderly individuals with low educational levels. Therefore, the Towers of Kuwait-Arabic Neurocognitive Assessment (ToK-ArNA) was developed using similar psychometric features of Tower of London (ToL) test, and the unique architecture of Towers of Kuwait, with the potential to overcome the limitation of ToL color perception difficulties that might be encountered in subjects with hereditary or acquired color vision disorders. We enrolled 120 older Arabic-speaking Omanis from January 2022 to November 2022 and all participants underwent screening to ensure normal cognitive function before performing the ToL and ToK-ArNA tests. Validity, reliability, and non-parametric statistical tests were used for data analysis. A total of 85 participants, 51 men (60%) and 34 women (40%) met the inclusion criteria and completed the testing. Statistical analyses confirmed the validity and reliability of ToK-ArNA compared to ToL, with comparable total Time and Accuracy scores and more preference towered the ToK-ArNA among the participants. Despite the study limitations, these results indicate that the ToK-ArNA is a reliable and applicable executive and visuospatial function assessment tool and further studies are warranted to establish its validity in patients with various neurocognitive disorders

Leber’s idiopathic stellate neuroretinitis - A clinical case

Neuroretinitis is a type of optic neuropathy characterized by an acute unilateral visual loss with optic disc swelling and macular star. A 26-year-old male presented with sudden blurring of vision in the right eye for 15 days. There were no other constitutional symptoms. On examination, visual acuity and color vision were impaired in the right eye. Visual-evoked potential showed a lower amplitude with increased latency on the right side. Perimetry showed centrocaecal scotoma. The right eye fundus showed a distinct neuroretinitis pattern Despite extensive investigation, no specific cause was identified, hence diagnosed as Leber’s idiopathic stellate neuroretinitis. The patient was started on oral prednisolone. Follow-up showed significant improvement.

Traumatic Optic Neuropathy Treatment Trial 2 (TONTT-2): evaluating the efficacy of different doses of erythropoietin – a multicentre, randomised, double-blind clinical trial

AimThe aim is to compare the efficacy and safety of three different weight-adjusted intravenous erythropoietin (EPO) doses in patients with indirect traumatic optic neuropathy (TON).MethodsThis study is a multicentre, randomised,...

Efficacy of ChromaGen lenses in enhancing color perception in color vision deficiency: a critical evaluation

Aims: Despite advancements in color vision correction, evidence supporting the efficacy of ChromaGen haploscopic filter systems in improving color perception remains limited. This study primarily investigates the performance of ChromaGen lenses (CL). Methods: The study included 27 volunteers diagnosed with color vision deficiency (CVD). An anomaloscope was used to detect color vision defects. Participants underwent color vision tests (Ishihara and Panel D15) both with and without CL. The results were statistically analyzed. Results: All participants were male, aged 21 to 57. Among them, 12 (44%) had protan defect (10 protanopes, 2 protanomalies) and 15 (56%) had deutan defect (12 deuteranopes, 3 deuteranomalies). Without CL, protan defect participants read 2.0±1.0 pages on the Ishihara test, while deutan defect participants read 3.0±1.9 pages. With CL, protan defect participants read 4.5±2.2 pages and deutan defect participants read 14.2±0.9 pages, showing statistically significant improvement (p<0.05). The difference between protan and deutan groups was also statistically significant (p<0.05). In the Panel D15 test, without the use of CL 81% of individuals with protanopia and deuteranopia made significant errors, whereas participants with protanomaly and deuteranomaly performed well. No significant improvement was noted with CL in the Panel D15 results. Twenty-three participants preferred magenta and four preferred pink CL. Fifteen participants expressed interest in using CL solely to pass the Ishihara test. Conclusion: This study concludes that commercially available ChromaGen filters do not provide clinically significant evidence of improved subjective color perception. Therefore, recommending these devices to the CVD population for color perception may not be highly beneficial. However ChromaGen lenses may be used by some CVD patients to pass the Ishihara test.

Individual color matching functions from cross‐media color‐matching experiment

AbstractHuman color vision exhibits substantial variability, challenging the accurate measurement and reproduction of individual color appearances. This paper introduces a novel cross‐media color‐matching experiment that combines physical pigments and digital displays, providing a practical and efficient solution to measure individual color matching functions (CMFs). By using the Kubelka–Munk theory to synthesize broadband spectral pigments, optimized metameric pairs can be created to significantly differentiate categorical observers. Psychophysical experiment results reveal the superiority of specific CMFs for individual observers, surpassing standard models like the CIE 1931 2‐degree CMFs. This study also underscores the significance of employing CMFs for personalized color reproduction and explores the potential benefits of using higher bit‐depth displays, narrower‐band displays, and increasing repetition counts to enhance the accuracy of the color matching process.

Color Vision Deficiency Recognition Based on Eye-Tracking Metrics Using Machine Learning Approaches

Individuals with color vision deficiency (CVD) face many difficulties and limitations in their daily lives and professional activities, some of which may prove life-threatening. These negative factors necessitate the development of methods for the identification and classification of CVD. Because CVD is a vision impairment, it is crucial to determine if its presence can be predicted with eye behavior. An experiment was conducted using a driving simulator and eye-tracking glasses. The experiment included 27 people with CVD (12 with deuteranopia, 9 with deuteranomaly, 3 with protanopia, and 3 with protanomaly) and 10 people with normal color vision. Each participant performed multiple driving attempts with color-coded guidelines on the navigator to assess visual search ability. Based on data recorded by an eye tracker, the following three types of cross-validated models were developed: binary classification (presence and absence of CVD), a three-class model to recognize the absence of CVD, protanopia, and deuteranopia, and a five-class model to predict the absence of CVD, deuteranopia, deuteranomaly, protanopia, and protanomaly. These three models yielded respective accuracy levels of over 95%, 66%–78%, and 43%–52%. Overall, it was found that eye-tracking metrics have the potential to classify and predict CVD.

A review on achromatopsia: Exploring genetic basis, diagnostic innovations, and therapeutic prospects

Achromatopsia (ACHM) is a rare inherited retinal disorder characterized by partial or complete color blindness, which impacts individuals' quality of life and daily functioning. This review delves into the genetic basis, diagnostic innovations, and therapeutic prospects associated with ACHM. The main objective is to comprehensively explore the current understanding of ACHM, including genetic mutations, diagnostic techniques, and management approaches, while also discussing potential therapeutic interventions. Achromatopsia primarily results from mutations in genes encoding cone photoreceptor proteins, such as GNAT2, ATF6, PDE6H, PDE6C, CNGA3, and CNGB3. Various diagnostic methods, including electroretinography (ERG) and optical coherence tomography (OCT), are pivotal in confirming ACHM diagnosis by assessing cone function and structural abnormalities in dysfunctional cone cells. This review also highlights gene therapy interventions aimed at restoring cone function, highlighting promising advancements in preclinical and clinical settings. Additionally, it discusses the clinical features of ACHM, such as reduced visual acuity, photophobia, and color vision impairment, emphasizing the need for tailored management strategies to increase patients' quality of life. This review underscores the complex genetic landscape of ACHM and the importance of accurate diagnosis through advanced diagnostic modalities such as ERG and OCT. While there is currently no cure for ACHM, management approaches focus on symptom alleviation and improving patients' daily functioning. Gene therapy has emerged as a promising avenue for potential treatment, with ongoing research aiming to address the underlying genetic defects and restore cone photoreceptor function. The findings of this review hold clinical relevance by providing insights into the pathogenesis, diagnosis, and management of ACHM, guiding healthcare professionals in delivering personalized care to affected individuals. Continued research and advancements in gene therapy offer hope for future therapeutic interventions, highlighting the importance of updating the latest developments in the field of ACHM.

Patterns of refractive errors and visual function in school-going children in South Africa

Background: Uncorrected refractive error is the most significant contributor of VI in children and is usually detected through vision screenings or scheduled eye and vision examinations conducted among school children.Aim: To describe patterns of refractive errors (RE), visual function and amblyopia in school-going children.Setting: Mankweng, Polokwane, South Africa.Methods: Retrospective chart reviews were conducted on 837 clinical record cards of children attending selected schools and who were screened between 2019 and 2021 at the University of Limpopo Optometry clinic. Purposive sampling was used to sample the clinical record cards.Results: About 134 children (16%) reported blurred vision, 197 (23.5%) failed distance visual acuity screening, while 173 (20.7%) had RE. Myopia among 168 (9.6%) children was the most common RE, followed by astigmatism and hyperopia at 60 (4.70%) and 28 (4.4%), respectively. Furthermore, 14 (1.7%) children had anisometropia. Amblyopia, colour vision deficiency and contrast sensitivity were also detected at prevalence rates of 4.4%, 9.8% and 8.2%, respectively.Conclusion: Vision screenings and regular comprehensive eye examinations are commonly conducted to detect and manage REs to prevent or delay the onset of amblyopia and strabismus. Children had a high prevalence of RE and amblyopia, which is similar to global estimates.Contribution: To describe the pattern of REs, amblyopia and visual function, which is critical to understand the prevalence of amblyopia and associated conditions. Knowing the patterns of these conditions may provide an impetus for the implementation of strategies such as vision screenings and vision examinations in schools.

Risk of Nonarteritic Anterior Ischemic Optic Neuropathy in Patients Prescribed Semaglutide

Background: Non-arteritic anterior ischemic optic neuropathy is the most common acute optic neuropathy in patients older than 50 years. Risk factors for NAION are structural crowding of disc, diabetes, systemic hypertension, hyperlipidaemia, smoking. Patients present with sudden monocular vision loss, dyschromatopsia, visual field defect, disc edema diffuse or segmental. Objectives: To evaluate risk of non arteritic anterior ischemic optic neuropathy after routine treatment. Method: This Longitudinal observational study was carried out from January 2016 to June 2016 at Department of Neuro-Ophthalmology, National Institute of Ophthalmology & Hospital, Sher -E-Bangla Nagar, Dhaka among Sixty cases. Detailed information were obtained in each cases according to protocol. A complete history was taken from the patient. Relevant investigation reports were collected. Selected patients were undergone detailed ophthalmological and systemic evaluation. They were treated at NIO&H with following measure like proper counseling, controlling of risk factors like diabetes, hypertension, hyperlipidaemia and were advised to take tablet vitamin B1, B6 & B12. They were followed up at 1st week, 4th week & 8th week. In each visit visual acuity, color vision, field of vision, RAPD & optic disc changes were recorded in a pre- designed data collection sheet. All the information’s were recorded according to fixed protocol. Results: Among the 60 cases, mean age was 55.67 (±4.89) years, minimum age was 51 and maximum age 69 years. Majority 32(53.3%) were male and 28(46.67%) were female. Associated risk factor like diabetes, hypertension, hyperlipidaemia and sleep apnea which were 53.3%, 36.67%, 30% and 13.3% respectively. Different disc changes of the study population were segmental disc swelling 36(60%) and diffuse disc swelling 24(40%) respectively. Regarding distant visual acuity patients were grouped into 6/6 to 6/12 group, 6/18-6/36 group, 6/60- 1/60 group and counting finger to hand movement group. At presentation most of the patient belongs to 6/6- 6/12 group which was 26(43.33%) followed by 6/18-6/36 group, it was 18(30%), 10(16.67%) were included in (6/60-1/60) group and the rest 06(10%) were included in counting finger to hand movement group. At final visit on 8th week 20(35.7%) patients remain in 6/6-6/12 group and also 6/18-6/36 group includes 20(35.7%) patients, 10(16.67%) were included in (6/60-1/60) group and the rest 06(10%) were included in counting finger to hand movement group. RAPD present in pretreatment 52(86.7%) and in post treatment were 46(82.14%). (p>0.05) that was not statistically significant. Color vision dyschromatopsia in pretreatment 46(76.7%) and in post treatment were 37(60%). In post treatment 06(10.71%) were normal color vision. (p<0.5) that was statistically significant. ocular involvement 52(86.67%) were 1st eye and 08(13.3%) were 2nd eye. Comparison of pre-treatment and post treatment visual field were Arcuate scotoma 12(20%) vs 09(16.07%), Inferior Altitudinal field defect 32(53.33%) vs 31(57.14%), Superior Altitudinal field defect 02(3.3%) vs 02(3.57%) respectively. Conclusion: In study no significant change found on visual acuity, colour vision and field of vision after treatment of non-arteritic anterior ischemic optic neuropathy.

Parallel Spectral Tuning of a Cone Visual Pigment Provides Evidence for Ancient Deep-Sea Adaptations in Cetaceans.

Dichromatic color vision is mediated by two cone visual pigments in many eutherian mammals. After reentry into the sea, early cetaceans lost their violet-sensitive visual pigment (short wavelength-sensitive 1) independently in the baleen and toothed whale ancestors and thus obtained only monochromatic cone vision. Subsequently, losses of the middle/long wavelength-sensitive (M/LWS) pigment have also been reported in multiple whale lineages, leading to rhodopsin (RH1)-mediated rod monochromatic vision. To further elucidate the phenotypic evolution of whale visual pigments, we assessed the spectral tuning of both M/LWS and RH1 from representative cetacean taxa. Interestingly, although the coding sequences for M/LWS are intact in both the pygmy right whale and the Baird's beaked whale, no spectral sensitivity was detected in vitro. Pseudogenization of other cone vision-related genes is observed in the pygmy right whale, suggesting a loss of cone-mediated vision. After ancestral sequence reconstructions, ancient M/LWS pigments from cetacean ancestors were resurrected and functionally measured. Spectral tuning of M/LWS from the baleen whale ancestor shows that it is green sensitive, with a 40-nm shift in sensitivity to a shorter wavelength. For the ancestor of sperm whales, although no spectral sensitivity could be recorded for its M/LWS pigment, a substantial sensitivity shift (20 to 30 nm) to a shorter wavelength may have also occurred before its functional inactivation. The parallel phenotypic evolution of M/LWS to shorter wavelength sensitivity might be visual adaptations in whales allowing more frequent deep-sea activities, although additional ecological differentiations may have led to their subsequent losses.