The genetics and evolution of eye color in domestic pigeons (Columba livia).

The eye color of birds, generally referring to the color of the iris, results from both pigmentation and structural coloration. Avian iris colors exhibit striking interspecific and intraspecific variations that correspond to unique evolutionary and ecological histories. Here, we identified the genetic basis of pearl (white) iris color in domestic pigeons (Columba livia) to explore the largely unknown genetic mechanism underlying the evolution of avian iris coloration. Using a genome-wide association study (GWAS) approach in 92 pigeons, we mapped the pearl iris trait to a 9 kb region containing the facilitative glucose transporter gene SLC2A11B. A nonsense mutation (W49X) leading to a premature stop codon in SLC2A11B was identified as the causal variant. Transcriptome analysis suggested that SLC2A11B loss of function may downregulate the xanthophore-differentiation gene CSF1R and the key pteridine biosynthesis gene GCH1, thus resulting in the pearl iris phenotype. Coalescence and phylogenetic analyses indicated that the mutation originated approximately 5,400 years ago, coinciding with the onset of pigeon domestication, while positive selection was likely associated with artificial breeding. Within Aves, potentially impaired SLC2A11B was found in six species from six distinct lineages, four of which associated with their signature brown or blue eyes and lack of pteridine. Analysis of vertebrate SLC2A11B orthologs revealed relaxed selection in the avian clade, consistent with the scenario that during and after avian divergence from the reptilian ancestor, the SLC2A11B-involved development of dermal chromatophores likely degenerated in the presence of feather coverage. Our findings provide new insight into the mechanism of avian iris color variations and the evolution of pigmentation in vertebrates.

Anterior segment optical coherence tomography angiography for iris vasculature in pigmented eyes.

PURPOSE: To compare anterior segment optical coherence tomography angiography (AS-OCTA) systems in delineating normal iris vessels and iris neovascularisation (NVI) in eyes with pigmented irides. METHODS: Prospective study from January 2019 to June 2019 of 10 consecutive patients with normal pigmented iris, had AS-OCTA scans with a described illumination technique, before using the same protocol in five eyes with NVI (clinical stages 1-3). All scans were sequentially performed using a spectral-domain OCTA (SD-OCTA), and a swept-source OCTA (SS-OCTA, Plex Elite 9000). Images were graded by two masked observers for visibility, artefacts and NVI characteristics. The main outcome measure was iris vessel density measurements comparing SS-OCTA and SD-OCTA systems. RESULTS: The median age of subjects was 28 (20-35) years, and 50% were female. The paired mean difference of iris vessel density measurements was 11.7 (95% CI 14.7 to 8.1; p=0.002), SS-OCTA detecting more vessels than SD-OCTA. The inter-rater reliability for artefact score (κ=0.799, p<0.001) and visibility score (κ=0.722; p<0.001) were substantial. Both AS-OCTA systems were able to detect NVI vessels with a fair agreement (κ=0.588), with clearer NVI characteristics in stage 1/2 compared to stage 3 NVI (mean difference NVI score: 2.7±0.4, p=0.009). CONCLUSION: The SS-OCTA was better able to delineate iris vessels in normal pigmented irides compared to SD-OCTA. Both AS-OCTA systems identified NVI characteristics based on its atypical configuration or location, but further improvements are needed to allow for more accurate objective, serial quantification for clinical use.

Iris Colour and the Risk of Developing Uveal Melanoma.

Uveal melanoma (UM) is a global disease which especially occurs in elderly people. Its incidence varies widely between populations, with the highest incidence among Caucasians, and a South-to-North increase in Europe. As northern Europeans often have blond hair and light eyes, we wondered whether iris colour may be a predisposing factor for UM and if so, why. We compared the distribution of iris colour between Dutch UM patients and healthy Dutch controls, using data from the Rotterdam Study (RS), and reviewed the literature regarding iris colour. We describe molecular mechanisms that might explain the observed associations. When comparing a group of Dutch UM patients with controls, we observed that individuals from Caucasian ancestry with a green/hazel iris colour (Odds Ratio (OR) = 3.64, 95% Confidence Interval (CI) 2.57-5.14) and individuals with a blue/grey iris colour (OR = 1.38, 95% CI 1.04-1.82) had a significantly higher crude risk of UM than those with brown eyes. According to the literature, this may be due to a difference in the function of pheomelanin (associated with a light iris colour) and eumelanin (associated with a brown iris colour). The combination of light-induced stress and aging may affect pheomelanin-carrying melanocytes in a different way than eumelanin-carrying melanocytes, increasing the risk of developing a malignancy.

Molecular and biochemical mechanisms of human iris color: A comprehensive review.

Eye color is determined as a polymorphism and polygenic trait. Brown is the most common eye color in the world, accounting for about 79%, blue eye color for about 8-10%, hazel for 5%, and green for 2%. Rare-colored eyes include gray and red/violet. Different factors are involved in determining eye color. The two most important factors are the iris pigment and the way light is scattered from the iris. Gene expression determines the iris pigmentation and how much melanin is present in the eye, which is the number of melanin subunits that identify eye color. The genes involved in the pigmentation of single-nucleotide polymorphism (SNP) have a significant role; and even some genes are included only in the eye color through SNP. MicroRNAs also affect melanocyte synthesis, which is usually affected by the downregulation of essential genes involved in pigmentation. In this study, we assess the biochemical pathways of melanin synthesis, and the role of each gene in this pathway also has been examined in the signaling pathway that stimulates melanin synthesis.

A Matador-like Predator Diversion Strategy Driven by Conspicuous Coloration in Guppies.

Understanding the adaptive function of conspicuous coloration has been a major focus of evolutionary biology for much of the last century. Although considerable progress has been made in explaining how conspicuous coloration can be used in functions as diverse as sexual and social signaling, startling predators, and advertising toxicity [1], there remain a multitude of species that display conspicuous coloration that cannot be explained by existing theory. Here we detail a new "matador-like" divertive antipredator strategy based on conspicuous coloration in Trinidadian guppies (Poecilia reticulata). Guppies encountering predatory fish rapidly enhance the conspicuousness of their eyes by blackening their irises. By pitting biomimetic robotic guppies against real predatory fish, we show this conspicuous eye coloration diverts attacks away from the guppies' center of mass to their head. To determine the function of this seemingly counterintuitive behavior, we developed a method for simulating escape probabilities when live prey interact with ballistic attacking predators, and find this diversion effect significantly benefits black-eyed guppies because they evade capture by rapidly pivoting away from the predator once it has committed to its attack. Remarkably, this antipredator strategy reverses the commonly observed negative scaling relationship between prey size and evasive ability, with larger fish benefiting most from diverting predators. Taken together, our results introduce a new antipredator divertive strategy that may be widely used by conspicuously colored prey that rely on agility to escape their predators.

Establishing a normative database for quantitative pupillometry in the pediatric population.

BACKGROUND: Pupillary evaluation is a crucial element of physical exams. Noting size, reactivity, and consensual response is critical in assessing for optic nerve dysfunction. We aim to establish normative data for scotopic pupillary size and function in the pediatric population in a clinical setting. METHODS: Pupillometry was obtained prospectively for consecutive, normal patients < 18 years old being evaluated by Lurie Children's Ophthalmology. Quantitative data included maximum (MAX) and minimum (MIN) diameters, constriction percentage (CON), latency (LAT), average (ACV) and maximum (MCV) constriction velocities, average dilation velocity (ADV), and 75% recovery time (T75). Iris color was noted as light, intermediate, or dark. RESULTS: 196 eyes of 101 participants (42.6% male, ages 1-17 years, average age 10.3 years) were analyzed. Mean MAX was 6.6 mm (5.1-8.1 mm 95% CI); MIN was 4.7 mm (3.1-6.1 mm 95% CI); CON was 30% (17-42 95% CI); LAT was 230 milliseconds (160-300 ms 95% CI); ACV was 3.70 mm/sec (2.21-5.18 mm/sec 95% CI); and ADV was 0.88 mm/sec (0.38-1.38 mm/sec 95% CI). Age had a positive correlation with MAX, MIN, and CON. 84.2 and 95.8% of participants showed resting pupil asymmetry of ≤0.5 mm and ≤ 1.0 mm, respectively. CONCLUSIONS: Quantitative pupillometry can be a useful tool for screening pediatric patients. We sought to establish normative data in this group. We found males to have significantly greater MCV and CON than females (p < 0.05). Also, age had a positive correlation with MAX, MIN, and CON.

Effect of Iris Color on the Outcome of Descemet Membrane Endothelial Keratoplasty.

PURPOSE: To explore the impact of iris color on the outcome of Descemet membrane endothelial keratoplasty (DMEK). METHODS: Consecutive cases of Fuchs endothelial dystrophy after DMEK were retrospectively analyzed from the prospective Cologne DMEK database between 2011 and 2017 at the University of Cologne, Germany. Iris pictures were graded by color into blue, green, or brown and compared regarding outcome parameters including best-corrected visual acuity (converted to logarithm of the minimal angle of resolution), central corneal thickness, endothelial cell density (ECD), each at preoperative (baseline) and postoperative 12 months, rebubbling rates, cystoid macular edema (CME), and immune rejections after surgery. RESULTS: One thousand one hundred six eyes of 814 patients were included in this study that consisted of 354 blue eyes, 418 green eyes, and 244 brown eyes. There was no significant correlation between iris color and any parameter (best corrected visual acuity; P = 0.064 at preoperatively, P = 0.959 at 12 months) (ECD; P = 0.158 preoperatively, P = 0.859 at 12 months) (central corneal thickness; P = 0.148 preoperatively, P = 0.252 at 12 months). The loss of ECD at 12 months after surgery was 37.2% ± 1.0% in blue eyes, 37.2% ± 0.9% in green eyes, and 37.2% ± 1.2% in brown eyes (P = 0.999). Immune rejections were 1.7%, 2.9%, and 0.8% (P = 0.168) in blue, green, and brown eyes, respectively. Rebubbling rates and CME incidence were similar in each group (P = 0.129, and P = 0.552 respectively). CONCLUSIONS: The iris color has no significant impact on the outcome after DMEK. Thus, DMEK can be applied effectively, regardless of the iris color.

Iris colour and astigmatism among Chinese teenagers.

BACKGROUND/AIMS: Iris colour might contribute to refractive development, but it is uncertain whether it is related to astigmatism. We aim to examine the association of iris colour with the presence of astigmatism in a school-based sample of Chinese students. METHODS: 2346 grade 7 students from 10 middle schools aged 13 to 14 years in Southwestern China participated in the study. We obtained standardised slit-lamp photographs and developed a grading system assessing iris colour (higher grade denoting darker). Astigmatism was defined as a cylinder power of more than 0.50, 0.75 or 1.00 dioptre (D). Logistic regression models with generalised estimating equation were fitted to assess the relationship between iris colour and astigmatism, accounting for the correlation between both eyes. ORs and 95% CIs were presented. RESULTS: The overall prevalence of astigmatism for three different definitions was 30.4% (95% CI 28.6% to 32.2%) (<-0.5 D), 12.7 % (95% CI 11.3% to 14.0%) (<-0.75 D) and 5.3% (95% CI 4.4% to 6.2%) (<-1.0 D), respectively. In multivariate analysis adjusting for the effect of gender and height, darker iris colour was associated with an increasing trend of astigmatism (p for trend <0.05). Compared with individuals with iris colour of grade 4 or 5 (the darkest), those with grade 1 or 2 (the lightest) were significantly less likely to be affected by astigmatism (<-0.75 D) in gender-adjusted model (OR 0.67) and multivariate-adjusted model (OR 0.72). CONCLUSION: Darker iris colour might be a risk factor for astigmatism in Chinese adolescents.

Lack of tumour pigmentation in conjunctival melanoma is associated with light iris colour and worse prognosis.

AIM: To investigate whether differences in iris colour, skin colour and tumour pigmentation are related to clinical outcome in conjunctival melanoma. METHODS: Data of 70 patients with conjunctival melanoma from the Leiden University Medical Center (Leiden, The Netherlands) and 374 patients from the Wills Eye Hospital (Philadephia, USA) were reviewed. The relation between iris colour, skin colour and tumour pigmentation versus clinical parameters and outcome was investigated using univariate and multivariate regression analyses. RESULTS: A light iris colour (blue, grey, green) was present in 261 (59%) patients and a dark colour (hazel, brown) in 183 (41%). A low tumour pigmentation was detected in 130 (40%) and a high pigmentation in 197 (60%) patients. Low tumour pigmentation was associated with light iris colour (p=0.021) but not related to skin colour (p=0.92). In univariate analysis, neither iris nor skin colour was related to clinical outcome, while a low tumour pigmentation was related to metastasis formation (HR 2.37, p=0.004) and death (HR 2.42, p=0.020). In multivariate analysis, low tumour pigmentation was related to the development of recurrences (HR 1.63, p=0.043), metastasis formation (HR 2.48, p=0.004) and death (HR 2.60, p=0.014). CONCLUSION: Lightly pigmented tumours occurred especially in individuals with lightly coloured irises. While iris colour or skin colour was not significantly related to clinical outcome, a low tumour pigmentation was related to a worse outcome in patients with conjunctival melanoma. The amount and type of melanin in conjunctival melanocytes may be involved in the pathogenesis and behaviour of selected conjunctival melanoma.

Residual Iris Retraction Syndrome After Artificial Iris Implantation.

PURPOSE: To evaluate the effect of an artificial iris implant on the remnant iris. DESIGN: Interventional case series. METHODS: Setting: Single center. PATIENT POPULATION: Forty-two consecutive patients. OBSERVATION PROCEDURES: Morphologic evaluation over 24 ± 14 months. MAIN OUTCOME MEASURES: Remnant pupillary aperture, iris color, visual acuity, intraocular pressure, and endothelial cell count. RESULTS: In 7 of 42 cases (16.7%), the residual iris aperture dilated from 36.6 ± 15.4 mm2 preoperatively to 61.1 ± 12.5 mm2 1 year postoperatively (66.9% increase). In 5 of 7 affected eyes the artificial iris had been implanted into the ciliary sulcus; in 2 eyes it had been sutured to the sclera. Four of the 7 patients presented with remarkable complications: 2 eyes needed glaucoma shunt surgeries owing to pigment dispersion; 1 suffered from recurrent bleedings; and in 1 case artificial iris explantation was performed owing to chronic inflammation. Anterior chamber depth and angle, endothelial cell count, and visual acuity did not change in this cohort. Changes in color were not observed in the remnant iris. CONCLUSIONS: The implantation of an artificial iris prosthesis can lead to a residual iris retraction syndrome. It is likely that residual iris is trapped in the fissure between the artificial iris and the anterior chamber angle, preventing further pupil constriction. Another possibility could be a constriction or atrophy of the residual iris. A scleral-sutured implant and an implantation in the capsular bag were both found to prevent the iris retraction. The study group number is inadequate to allow statistical comparison of these different implantation methods. As the use of artificial irises increases, we may expect more patients with iris retraction syndrome in the future.

ASSESSMENT OF A VISUAL SCORING SYSTEM FOR IDENTIFYING AND QUANTIFYING ANEMIA IN MALE EASTERN BOX TURTLES ( TERRAPENE CAROLINA CAROLINA).

The North Carolina State University College of Veterinary Medicine Turtle Rescue Team (TRT) regularly admits wild eastern box turtles (EBT) ( Terrapene carolina carolina) for treatment and rehabilitation. Adult males of this species generally have an impressive red coloration of the iris, a feature commonly used to differentiate them from their brown-eyed female conspecifics. Male EBTs that present often display marked pallor of the eyes, which has accompanied clinical anemia. The aim of this study was to examine the relationship between eye color and packed cell volume (PCV) in adult male EBTs, and to assess the accuracy of using eye color to predict PCV. Eye-color scoring cards were created using Adobe Creative Cloud Photoshop®. Each card was composed of blocks displaying progressively lighter tints of a red hue, with a number (score) assigned to each block. Five-block, six-block, and nine-block scoring cards were prepared, with lower numbers (scores) corresponding to lighter hues. To determine the variation in subjective color scores assigned by different human observers, 85 individuals were asked to score EBT eye color in three animals using each of the three scoring cards. Eye color of adult male EBTs that presented to the TRT ( n = 18) and those housed at the North Carolina Museum of Natural Sciences ( n = 6) were scored using each of the three cards, immediately preceding venipuncture of the occipital sinus for determination of PCV. All animals were scored by at least two individuals. Turtles with low scores (pale eyes) using all three scoring cards consistently had lower PCVs. The five- and six-block scorecards had a positive predictive value (PPV) of 100% while the nine-block score card had a PPV of 71.4%. This specific and noninvasive method for estimating PCV of male EBTs is clinically desirable in both rehabilitation and hospital settings.

Is Eye Color Related to Dental Injection Pain? A Prospective, Randomized, Single-blind Study.

INTRODUCTION: Recent studies have investigated the relationship between pain perception and specific phenotypes such as red hair color and various eye colors. Further investigations into biomarkers as they relate to pain could be useful in understanding underlying genetic components involved in these pathways. Additionally, it would be clinically useful to determine if a patient would be more likely to experience pain during dental treatment based on eye color. The purpose of this study was to investigate a link between eye color and perceived injection pain in healthy, asymptomatic white women. METHODS: Three hundred healthy, adult, white female patients were included, 133 with dark eyes and 167 with light eyes. Dental anxiety was assessed with the Corah Dental Anxiety Scale. Subjects with their eye color masked by dark glasses received a right maxillary lateral incisor infiltration of 1 cartridge of 2% lidocaine with 1:100,000 epinephrine. Patients rated their injection pain on a 170-mm Heft-Parker visual analog scale. Photographs of the subjects' eyes were taken after the infiltrations and categorized into dark- and light-eyed groups by 3 independent observers. Comparisons for injection pain were analyzed using analysis of variance and the Tukey-Kramer test. RESULTS: No significant differences were found for pain of injection between dark- or light-eyed subjects. CONCLUSIONS: Eye color was not shown to be a predictor for injection pain in white women. Therefore, eye color would not be clinically useful in determining if a patient would be more likely to experience pain during dental treatment.

Asymmetry of eye color in the common cuckoo.

Bilateral symmetry is assumed to contribute to the evolution of eye color, with the left and right eye being the same color in most vertebrates; yet, few studies tested this assumption. Here, we compared the amount of iris flecking (black spots presented on the iris) between the left and right eye of 76 adult common cuckoos Cuculus canorus. We found considerable variation in the total amount of iris flecking among individuals, with variation being associated with body size and sex. We also found that the amount of iris flecking differed between the left and right eye and that this left-right asymmetry was not random, with the left eye almost always being darker than the right eye. Furthermore, this asymmetry was negatively associated with wing length; however, this effect was limited to individuals with dark eyes. Overall, the asymmetric, but non-random, distribution of iris flecking between the left and right eye may indicate that selection pressures driving asymmetry (such as visual lateralization) act on the development of iris colors, even though this effect might be limited, due to the role of bilateral symmetry.

Pupal colour plasticity in a tropical butterfly, Mycalesis mineus (Nymphalidae: Satyrinae).

Lepidopteran insects have provided excellent study systems for understanding adaptive phenotypic plasticity. Although there are a few well-studied examples of adult plasticity among tropical butterflies, our understanding of plasticity of larval and pupal stages is largely restricted to temperate butterflies. The environmental parameters inducing phenotypic plasticity and the selective pressures acting on phenotypes are likely to differ across tropical and temperate climate regimes. We tested the influence of relative humidity (RH), a prominent yet under-appreciated tropical climatic component, along with pupation substrate, larval development time, pupal sex and weight in determining pupal colour in the tropical satyrine butterfly Mycalesis mineus. Pupae of this butterfly are either brown or green or very rarely intermediate. Larvae were reared at high (85%) and low (60%) RH at a constant temperature. Proportions of green and brown pupae were expected to vary across low and high RH and pupation substrates in order to enhance crypsis. Brown pupae were more common at low RH than at high RH, as predicted, and developed faster than green pupae. Pupal colour was correlated with pupation substrate. Choice of pupation substrate differed across RH treatments. It is unclear whether pupal colour influences substrate selection or whether substrate influences pupal colour. Our study underscores the need for further work to understand the basis of pupal plasticity in tropical butterflies.

Are Eyes a Mirror of the Soul? What Eye Wrinkles Reveal about a Horse's Emotional State.

Finding valid indicators of emotional states is one of the biggest challenges in animal welfare science. Here, we investigated in horses whether variation in the expression of eye wrinkles caused by contraction of the inner eyebrow raiser reflects emotional valence. By confronting horses with positive and negative conditions, we aimed to induce positive and negative emotional states, hypothesising that positive emotions would reduce whereas negative emotions would increase eye wrinkle expression. Sixteen horses were individually exposed in a balanced order to two positive (grooming, food anticipation) and two negative conditions (food competition, waving a plastic bag). Each condition lasted for 60 seconds and was preceded by a 60 second control phase. Throughout both phases, pictures of the eyes were taken, and for each horse four pictures per condition and phase were randomly selected. Pictures were scored in random order and by two experimenters blind to condition and phase for six outcome measures: qualitative impression, eyelid shape, markedness of the wrinkles, presence of eye white, number of wrinkles, and the angle between the line through the eyeball and the highest wrinkle. The angle decreased during grooming and increased during food competition compared to control phases, whereas the two phases did not differ during food anticipation and the plastic bag condition. No effects on the other outcome measures were detected. Taken together, we have defined a set of measures to assess eye wrinkle expression reliably, of which one measure was affected by the conditions the horses were exposed to. Variation in eye wrinkle expression might provide valuable information on horse welfare but further validation of specific measures across different conditions is needed.

What colour are newborns' eyes? Prevalence of iris colour in the Newborn Eye Screening Test (NEST) study.

PURPOSE: This study aims to assess the birth prevalence of iris colour among newborns in a prospective, healthy, full-term newborn cohort. METHODS: The Newborn Eye Screening Test (NEST) study is a prospective cohort study conducted at Lucile Packard Children's Hospital at Stanford University School of Medicine. A paediatric vitreoretinal specialist (DMM) reviewed images sent to the Byers Eye Institute telemedicine reading centre and recorded eye colour for every infant screened. Variables were graphed to assess for normality, and frequencies per subject were reported for eye colour, sex, ethnicity and race. RESULTS: Among 192 subjects screened in the first year of the NEST study with external images of appropriate quality for visualization of the irides, the birth prevalence of iris colour was 63.0% brown, 20.8% blue, 5.7% green/hazel, 9.9% indeterminate and 0.5% partial heterochromia. The study population was derived from a quaternary care children's hospital. We report the birth prevalence of iris colour among full-term newborns in a diverse prospective cohort. CONCLUSION: The study demonstrates a broad range of iris colour prevalence at birth with a predominance of brown iris coloration. Future studies with the NEST cohort will assess the change in iris colour over time and whether the frequencies of eye colour change as the child ages.

Eye color: A potential indicator of alcohol dependence risk in European Americans.

In archival samples of European-ancestry subjects, light-eyed individuals have been found to consume more alcohol than dark-eyed individuals. No published population-based studies have directly tested the association between alcohol dependence (AD) and eye color. We hypothesized that light-eyed individuals have a higher prevalence of AD than dark-eyed individuals. A mixture model was used to select a homogeneous sample of 1,263 European-Americans and control for population stratification. After quality control, we conducted an association study using logistic regression, adjusting for confounders (age, sex, and genetic ancestry). We found evidence of association between AD and blue eye color (P = 0.0005 and odds ratio = 1.83 (1.31-2.57)), supporting light eye color as a risk factor relative to brown eye color. Network-based analyses revealed a statistically significant (P = 0.02) number of genetic interactions between eye color genes and AD-associated genes. We found evidence of linkage disequilibrium between an AD-associated GABA receptor gene cluster, GABRB3/GABRG3, and eye color genes, OCA2/HERC2, as well as between AD-associated GRM5 and pigmentation-associated TYR. Our population-phenotype, network, and linkage disequilibrium analyses support association between blue eye color and AD. Although we controlled for stratification we cannot exclude underlying occult stratification as a contributor to this observation. Although replication is needed, our findings suggest that eye pigmentation information may be useful in research on AD. Further characterization of this association may unravel new AD etiological factors. © 2015 Wiley Periodicals, Inc.

Accuracy of self-reported nevus and pigmentation phenotype compared with clinical assessment in a population-based study of young Australian adults.

BACKGROUND: Awareness of individual risk may encourage improved prevention and early detection of melanoma. METHODS: We evaluated the accuracy of self-reported pigmentation and nevus phenotype compared with clinical assessment, and examined agreement between nevus counts from selected anatomical regions. The sample included 456 cases with invasive cutaneous melanoma diagnosed between ages 18 to 39 years and 538 controls from the population-based Australian Melanoma Family Study. Participants completed a questionnaire about their pigmentation and nevus phenotype, and attended a dermatologic skin examination. RESULTS: There was strong agreement between self-reported and clinical assessment of eye color [κ, = 0.78; 95% confidence interval (CI), 0.74-0.81]; and moderate agreement for hair color (κ = 0.46; 95% CI, 0.42-0.50). Agreement between self-reported skin color and spectrophotometer-derived measurements was poor (κ = 0.12; 95% CI, 0.08-0.16) to moderate (Spearman correlation rs = -0.37; 95% CI, -0.32 to -0.42). Participants tended to underestimate their nevus counts and pigmentation; men were more likely to underreport their skin color. The rs was 0.43 (95% CI, 0.38-0.49) comparing clinical total body nevus counts with self-reported nevus categories. There was good agreement between total body nevus counts and site-specific nevus counts, particularly on both arms. CONCLUSIONS: Young adults have suboptimal accuracy when assessing important risk characteristics including nevus numbers and pigmentation. Measuring nevus count on the arms is a good predictor of full body nevus count. IMPACT: These results have implications for the likely success of targeted public health programs that rely on self-assessment of these factors.

Don't it make your brown eyes blue? A comparison of iris colour across latitude in Australian twins.

BACKGROUND: The aim was to determine whether latitudinal (Queensland versus Tasmania) variation in reported disease frequency in Australia may be biased by differences in population. METHODS: A retrospective analysis was conducted from data of two large Australian twin studies (n = 1,835) having undertaken ophthalmic examination, namely, Twins Eye Study in Tasmania (TEST) and the Brisbane Adolescent Twins Study (BATS). Ordinal logistic regression was used to compute odds ratios and predicted probabilities for each category of eye colour by state. RESULTS: Tasmanian residence was associated with lower odds of darker iris colour (odds ratio 0.77, 95% CI [0.63-0.95]) signifying that participants living in Tasmania (TAS) are less likely to have darker-coloured irides than those residing in Queensland (QLD). For individuals living in Tasmania the predicted probability (TAS versus QLD) of having light blue eyes was greater (16.7 versus 13.3 per cent), approximately the same for green eyes and less for brown/dark brown-coloured eyes (6.2 versus 7.9 per cent). CONCLUSIONS: We found a general trend of individuals living in the southern states (TAS/VIC) of Australia having lighter-coloured irides compared to those living in the north (QLD). This finding has potential implications for all epidemiological research conducted to explore differences in UV-associated disease frequency in Australia, as population heterogeneity may confound the estimates obtained.

Eye color as a risk factor for acquired sensorineural hearing loss: a review.

Eye color may be an indicator of inner ear melanin content and has been associated with hearing loss. There is controversy as to whether eye color has an effect on acquired causes of sensorineural hearing loss. This review was conducted to analyze the literature evaluating the relationship between eye color and causes of sensorineural hearing loss. Six databases were searched to identify eligible studies. Included articles were independently assessed for quality by two authors. Eighteen articles were eligible for review. Eye color was not found to have an effect in the non-exposed population or in presbycusis. In noise-induced sensorineural hearing loss, light-eyed patients had more significant loss following noise exposure, although the variability reported due to eye color was modest (r(2) = 0.01-0.14). Two out of three studies reported that dark eye color is associated with cisplatin ototoxicity. In one study, green-eyed patients were found to be at higher risk of radiation-induced hearing loss. Eye color does not appear to play a role in hearing loss in non-exposed individuals or presbycusis. It is possible that dark-eyed individuals, with greater inner ear melanin content, are better protected against noise-induced hearing loss. Evidence suggests that melanin can be protective against radiation-induced sensorineural hearing loss, but may predispose individuals to cisplatin ototoxicity. Future studies are required to support these conclusions.