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The five features found most commonly in the human iris. The arrows are pointing to the features in images b, c and e. Fuchs’ crypts (a) are lacunae in the anterior border of the iris which arise during resorption of the pupillary membrane. They may be either large or small and closely resemble windows. Four sample crypts are outlined in the image above. Wolfflin nodules (b) are small bundles of collagen that are the consequence of atrophy in the stromal layer of the iris. Pigment spots (c) are discrete areas of pigmentation that can be observed on the surface of the iris. Spots that distort the stromal layer are referred to as nevi and spots that do not distort the stromal layer are referred to as freckles. Contraction furrows (d) are rings that extend around the outer border of the iris. They closely resemble wrinkles and are the product of the contraction and dilation of the pupil. Furrows are typically discontinuous and staggered across the iris. In the above image, the black line follows the path of the furrows around the eye. Conjunctival melanosis (e) is spotting that can be observed on the scleral region surrounding the iris. It is usually benign, and is found more commonly in some ancestries than in others.

The five features found most commonly in the human iris. The arrows are pointing to the features in images b, c and e. Fuchs’ crypts (a) are lacunae in the anterior border of the iris which arise during resorption of the pupillary membrane. They may be either large or small and closely resemble windows. Four sample crypts are outlined in the image above. Wolfflin nodules (b) are small bundles of collagen that are the consequence of atrophy in the stromal layer of the iris. Pigment spots (c) are discrete areas of pigmentation that can be observed on the surface of the iris. Spots that distort the stromal layer are referred to as nevi and spots that do not distort the stromal layer are referred to as freckles. Contraction furrows (d) are rings that extend around the outer border of the iris. They closely resemble wrinkles and are the product of the contraction and dilation of the pupil. Furrows are typically discontinuous and staggered across the iris. In the above image, the black line follows the path of the furrows around the eye. Conjunctival melanosis (e) is spotting that can be observed on the scleral region surrounding the iris. It is usually benign, and is found more commonly in some ancestries than in others.

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There are many textural elements that can be found in the human eye, including Fuchs' crypts, Wolfflin nodules, pigment spots, contraction furrows and conjunctival melanosis. Although iris surface features have been well-studied in populations of European ancestry, the worldwide distribution of these traits is poorly understood. In this paper, we d...

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... [24][25][26][27] Meanwhile, significant differences have also been observed between schizophrenic patients and healthy people in respect to pupil distance, corneal volume, anterior chamber volume, anterior chamber depth, and central corneal thickness. 28 The human iris is the most specific tissue in the eye and its structure is characterized by 8,14,29,30 crypts (defect of iris stroma), pigment spots, and wrinkles, as shown in Figure 1. Since 1956, studies have been carried out to examine the relationship between schizophrenia and iris color. ...
... This finding may be attributed to ethnic differences. For instance, Edwards et al 30 found that the distribution of iris wrinkles was similar among individuals of South Asian and European ancestry, whereas those of East Asian ancestry had significantly fewer iris wrinkles than those of South Asian and European ancestry. In addition, compared with healthy controls, a higher quantity of iris crypts was detected in the case group. ...
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Background: Recently, researchers have conducted many studies on the potential contribution of the retina and other eye structures on schizophrenia. This study aimed to evaluate differences in iris characteristics between patients with schizophrenia and healthy individuals so as to find more easily accessible and easily measurable biomarkers with a view to improving clinical assessments and furthering our understanding of the disease. Methods: Overall, 80 patients with schizophrenia and 52 healthy individuals were included in the case group and the control group, respectively. Iris images were collected from all subjects to compare differences in the structure and color of the iris. The Positive and Negative Symptom Scale (PANSS) and the Modified Overt Aggression Scale (MOAS) were used to evaluate the clinical symptoms and characteristics of 45 first-episode untreated schizophrenics, and analyzed correlations between iris characteristics and schizophrenia symptoms. Results: There were significant differences in iris crypts (P<0.05) and pigment spots (P<0.01) between the case and control group, but no significant difference was found in iris wrinkles (P<0.05). The logistic regression analysis demonstrated that the total iris crypts [odds ratio (OR) 1.166, 95% confidence interval (CI) 1.022-1.330] and total iris pigment spots (OR 1.815, 95% CI 1.186-2.775) increased the risk of suffering from schizophrenia. Furthermore, it was demonstrated that the number of iris crypts was positively associated with the MOAS score (r=0.474, P<0.01). Moreover, the number of the iris pigment spots (r=0.395, P<0.01) and wrinkles (r=0.309, P<0.05) were positively correlated with the subjects' negative symptom scores, respectively. Conclusion: Iris crypts and pigment spots were identified as potential biomarkers for detecting schizophrenia. In patients with first-episode untreated schizophrenia, iris characteristics may help psychiatrists to identify the illness and its severity, and to detect characteristic clinical symptoms.
... It is rich in texture, containing complex features that constitute numerous individual landmarks and variations in appearance across the eyes. [1][2][3] Variations in the spatial layout and colors are mostly distributed across two regions: an inner, pupillary region that extends to the collaret and an outer, ciliary region that extends to the sclera border, also called the limbus. The more thickly layered collaret lies between the inner and outer regions where the underlying constrictor and radial muscles touch. ...
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Purpose: It is unclear how the iris deforms during changes in pupil size. Here, we report an application of a multi-feature iris tracking method, which we call irissometry, to investigate how the iris deforms and affects the eye position signal as a function of pupil size. Methods: To evoke pupillary responses, we repeatedly presented visual and auditory stimuli to healthy participants while we additionally recorded their right eye with a macro lens-equipped camera. We tracked changes in iris surface structure between the pupil and sclera border (limbus) by calculating local densities (distance between feature points) across evenly spaced annular iris regions. Results: The time analysis of densities showed that the inner regions of the iris stretched more strongly as compared with the outer regions of the iris during pupil constrictions. The pattern of iris densities across eccentricities and pupil size showed highly similar patterns across participants, highlighting the robustness of this elastic property. Importantly, iris-based eye position detection led to more stable signals than pupil-based detection. Conclusions: The iris regions near the pupil appear to be more elastic than the outer regions near the sclera. This elastic property explains the instability of the pupil border and the related position errors induced by eye movement and pupil size in pupil-based eye-tracking. Tracking features in the iris produce more robust eye position signals. We expect that irissometry may pave the way to novel eye trackers and diagnostic tools in ophthalmology.
... The role of iris surface features in ocular function and their associations with other ocular tissues are yet to be clarified. The distribution of iris surface features varies by age, race, and gender [10]. Therefore, in this study, we focus our target population on young myopes who are refractive surgery candidates to see the impact of iris surfaces features on corneal biomechanics and assist preoperative evaluations of corneal status before laser refractive surgeries. ...
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Purpose. Iris biological features such as surface features and profile characteristics reflected the development of iris stroma and microvessels. Iris vessels and microcirculation are still lack of effective detection methods, and we can directly observe only the iris surface biological characteristics. This cross-sectional study evaluated the association between iris surface biological features and corneal biomechanics in young adults with myopia. Methods. We recruited 152 patients with myopia aged ≥18 years, from the Eye Hospital of Wenzhou Medical University, who had complete Corneal Visualization Scheimpflug Technology (Corvis ST) data and graded iris surface features. Iris surface features included crypts, furrows, and color measured from digital slit lamp images. The biomechanical properties of the cornea were assessed using Corvis ST. Only 1 eye of each participant was randomly selected for analysis. Associations between the iris surface features and corneal biomechanics were analyzed using linear regression models. The grade of iris crypts, furrows, and color and corneal biomechanical parameters measured with Corvis ST was the main outcome measures. Results. The iris crypts were significantly associated with deflection amplitude at the first applanation (A1 DLA, , ), A1 delta arc length (A1 dArcL) (, ), maximum delta arc length (dArcLM) (, ), and stiffness at the first applanation (SP-A1) (, ). The iris furrows were only associated with integrated radius (, ). Iris color was found not related with corneal biomechanical parameters measured via Corvis ST. Conclusions. Iris surface features were associated with corneal biomechanical properties in myopic eyes; more iris crypts were associated with lower corneal stiffness while more extensive furrows were related with higher corneal stiffness. Iris crypts and furrows may provide useful information on corneal biomechanical properties in myopic eyes. 1. Introduction Cornea is an important part of the refractive system of the human eye, and its refractive power accounts for more than 3/4 of the whole refractive system. Laser corneal refractive surgery can correct ametropia by cutting the corneal stroma to change the curvature of the anterior surface. Refractive surgery for myopia will reduce the number of central corneal lamellar and change the structure and biomechanical properties of cornea [1]. Different cutting methods and depths have different effects, which may affect the predictability of surgery and the occurrence of complications such as refractive regression and keratectasia [2, 3]. Therefore, the biomechanical properties of the cornea play an important role in the maintenance of the cornea shape and the design of refractive surgery, especially in the diagnosis of some latent corneal diseases such as keratoconus and other keratectasia before refractive surgery. Sufficient evaluation of the corneal biomechanical properties has a strong guiding significance for the safety of refractive surgery. Noninvasive measures of corneal biomechanics in vivo mainly include electronic speckle pattern interferometry (ESPI), ocular response analyzer (ORA), and Corneal Visualization Scheimpflug Technology (Corvis ST, Oculus, Wetzlar, Germany). [4] However, in China, only a few refractive surgery centers have the equipment to examine the corneal biomechanics. In the absence of such equipments, doctors cannot determine the patient’s corneal biomechanical properties initially. Cornea is also part of the outmost layer of the eyeball, and the corneal biomechanics was reported to have relationship with the elasticity of the sclera, lamina cribrosa, and peripapillary ring [4]. So far, as we know, the expansions in the inner ocular tissue, particularly the iris, are less studied. The iris has a variety of biological features such as intuitive surface features and profile morphological characteristics of iris stroma and microvessels. All these characteristics reflect the development of iris stroma and vascular circulation. Iris blood vessels and microcirculation still lack of effective detection methods, and we can directly observe only the iris surface biological characteristics. A grading system was recently established to evaluate the iris surface features, including iris crypts, furrows, and color that are observable under a slit lamp. [5] However, the role of iris surface features in ocular function and their associations with other ocular tissues are yet to be fully elucidated. Chua et al. [6] speculated that as crypts surrogate iris stroma, iris having more crypts is more compressible. Thus, iris crypts may be related with iris biomechanics. Nevertheless, to date, the human iris biomechanics has not been measured in vivo. As part of cornea and iris are of mesodermal origin, we postulate that the iris biomechanics is related with corneal biomechanics [7, 8]. No modality is currently available to directly measure iris biomechanics in humans. Exploring the relationship between the corneal biomechanical properties and iris features may improve the safety of refractive surgeries. Iris surface features, which can be examined under a slit lamp, have been suggested to be associated with iris biomechanics. Thus, this study is aimed at exploring the relationships of iris surface features including iris crypts, furrows, and color with corneal biomechanics. 2. Methods 2.1. Participants This prospective study recruited Chinese refractive surgery candidates aged older than 18 years. Participants with ocular pathology other than refractive error were excluded. A simple randomization method was used to select the left eye or the right eye based on a randomized number table according to the order the participants that were recruited. Approval was obtained from the Institutional Review Board (IRB) of Wenzhou Medical University (IRB approval number: 2020-128-K-113), and the study was conducted according to the tenets of the Declaration of Helsinki. Written informed consent was obtained from all participants. 2.2. Ocular Examinations All participants underwent standard detailed ophthalmic examinations including slit lamp examination, manifest refraction measurement (spherical equivalence, [SE]), and best corrected distance visual acuity. All examinations were performed by an experienced ophthalmologist. The patients also underwent corneal tomography with the Pentacam (Oculus, Wetzlar, Germany), anterior chamber depth (ACD) measurement using the IOL-Master (Carl Zeiss Meditec, Jena, Germany), and biomechanical property assessment using the Corvis ST (Oculus, Wetzlar, Germany). 2.3. Iris Photography and Grading Iris photography was performed with reference to the procedure by Sidhartha et al. [5] Briefly, the color iris images of both eyes were taken using a slit lamp digital camera (DC3; Topcon, Tokyo, Japan) at ×16 magnification in a dark room (20 lux) without flash. The images were captured under an illumination of 45° temporally and a brightness of 30% maximum light beam with a width of >20 mm and height of 14 mm. The iris crypts and furrows were graded as follows (Figure 1): iris crypts were categorized into 5 grades as grade 1, no crypts; grade 2, 1-3 crypts, grade 3, at least 4 crypts with a ; grade 4, at least 4 crypts with a ; and grade 5, numerous crypts with a , nearly covering the whole iris. Meanwhile, furrows were categorized into three grades based on circumferential extent and the number of furrows: grade 1, no furrows; grade 2, less than 5 furrows and the extent was ≤180°; and grade 3, at least 5 furrows present, and the extent was ≥180°. The iris color was also graded according to Sidhartha’s criteria in which darker iris was given higher grades [5]. Iris color was divided into 5 grades, but no patient in this study manifested grade 5 iris color.
... Muscular fibres within the iris membrane control the transitioning between pupil states. [21] The capillaceous tissue strands of the eye are transparent to permit light transference from the iris membrane into the retinal lens. This is an important design factor in the development of a synthetic iris membrane as light transference into the LDR is essential for an accurate photo-response and the control of pupil actuation. ...
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This study employs a novel 3D engineered robotic eye system with dielectric elastomer actuator (DEA) pupils and a 3D sculpted and colourised gelatin iris membrane to replicate the appearance and materiality of the human eye. A camera system for facial expression analysis (FEA) was installed in the left eye, and a photo-resistor for measuring light frequencies in the right. Unlike previous prototypes, this configuration permits the robotic eyes to respond to both light and emotion proximal to a human eye. A series of experiments were undertaken using a pupil tracking headset to monitor test subjects when observing positive and negative video stimuli. A second test measured pupil dilation ranges to high and low light frequencies using a high-powered artificial light. This data was converted into a series of algorithms for servomotor triangulation to control the photosensitive and emotive pupil dilation sequences. The robotic eyes were evaluated against the pupillometric data and video feeds of the human eyes to determine operational accuracy. Finally, the dilating robotic eye system was installed in a realistic humanoid robot (RHR) and comparatively evaluated in a human-robot interaction (HRI) experiment. The results of this study show that the robotic eyes can emulate the average pupil reflex of the human eye under typical light conditions and to positive and negative emotive stimuli. However, the results of the HRI experiment indicate that replicating natural eye contact behaviour was more significant than emulating pupil dilation.
... Muscular fibres within the iris membrane control the fluidic transitioning between open and closed pupilar states. Edwards et al. (2016) explain that the capillaceous tissue strands of the eye are transparent to permit light transference from the iris membrane into the retinal lens. This process is a crucial design factor in the development of a synthetic iris membrane as light transference into the LDR is essential for accurate photoresponsivity and the control of pupilar actuation. ...
... In addition to light regulation, the human iris responds to emotional stimuli. According to Edwards et al. (2016), during elevated states of emotional arousal, the pupil involuntarily expands up to 8mm in diameter. However, a more recent study by Kinner et al. (2017) measuring natural pupil dilation responses to emotion argues that the maximum and minimum pupillary dilation ranges to an emotional stimulus is 3.7mm-7.6mm ...
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The human face is the most natural interface for face-to-face communication, and the human form is the most effective design for traversing the human-made areas of the planet. Thus, developing realistic humanoid robots (RHRs) with artificial intelligence (AI) permits humans to interact with technology and integrate it into society in a naturalistic manner insurmountable to any other form of non-biological human emulation. However, RHRs have yet to attain a level of emulation that is indistinguishable from the human condition and fall into the uncanny valley (UV). The UV represents a dip in human perception, where affinity decreases with heightened levels of human likeness. Per qualified research into the UV, artificial eyes and mouths are the primary propagators of the uncanny valley effect (UVE) and reduce human likeness and affinity towards RHRs. In consideration, this thesis introduces, tests and comparatively assesses a pair of novel robotic eye prototypes with dilating pupils capable of simultaneously replicating the natural pupilar responses of the human eyes to light and emotion. The robotic pupil systems act as visual signifiers of sentience and emotion to enhance eye contact interfacing in human-robot interaction (HRI). Secondly, this study presents the design, development and application of a novel robotic mouth system with buccinator actuators and custom machine learning (ML) speech synthesis to mouth articulation application for forming complex lip shapes (visemes) to emulate human mouth and lip patterns to vowel and consonant sounds. The robotic eyes and mouth system were installed in two RHRs named ‘Euclid and Baudi’ and tested for accuracy and processing rate against a living human counterpart. The results of these experiments indicated that the robotic eyes are capable of dilating within the average pupil range of the human eyes to light and emotion, and the robotic mouth operated with a 86.7% accuracy rating when compared against the lip movement of a human mouth during verbal communication. An HRI experiment was conducted using the RHRs and biometric sensors to monitor the physiological responses of test subjects for cross-analysis with a questionnaire. The sample consists of twenty individuals with experience in AI and robotics and related fields to examine the authenticity, accuracy and functionality of the prototypes. The robotic mouth prototype achieved 20/20 for aesthetical, and lip synchronisation accuracy compared to a robotic mouth with the buccinator actuators deactivated, heightening the potential application of the system in future RHR design. However, to reduce influential factors, test subjects were not informed of the dilating eye system, which resulted in 2/20 of test subjects noticing the pupil dilation sequences to emotive facial expressions (FEs) and light. Moreover, the eye contact behaviours of the RHRs was more significant than pupil dilation FEs and eye aesthetics during HRI, counter to previous research in the UVE in HRI. Finally, this study outlines a novel theoretical evaluation framework founded on the 1950 Turing Test (TT) for AI, named The Multimodal Turing Test (MTT) for evaluating human-likeness and interpersonal and intrapersonal intelligence in RHR design and realistic virtual humanoids (RVHs) with embodied artificial intelligence (EAI). The MTT is significant in RHR development as current methods of evaluation, such as The Total Turing Test (TTT), Truly Total Turing Test (TTTT) Robot Turing Test (RTT), Turing Handshake Test (THT), Handshake Turing Test (HTT) and TT are not nuanced and comprehensive enough to evaluate the functions of an RHR/RVH simultaneously to pinpoint the causes of the UVE. Furthermore, unlike previous methods, the MTT provides engineers with a developmental framework to assess degrees of human-likeness in RHR and RVH design towards more advanced and accurate modes of human emulation.
... Ethnicity is important in determining the patterns of iris crypts. 25 Europeans and South Asians have greater number of crypts on the iris than do East Asians. 25 Whether PIC are associated with a greater frequency of angle dysgenesis in the general population needs to be evaluated. ...
... 25 Europeans and South Asians have greater number of crypts on the iris than do East Asians. 25 Whether PIC are associated with a greater frequency of angle dysgenesis in the general population needs to be evaluated. Iris features have been also shown to be greatly influenced by genetic patterns. ...
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Aim To classify unrelated patients with juvenile onset primary open angle glaucoma (JOAG) into clinically useful phenotypes using cluster analysis. Methods Out of the 527 unrelated patients with JOAG, the study included 414 patients who had all the phenotypic characteristics required for the study. A cluster analysis was performed to classify the patients based on their iris and angle morphology, age of onset, highest untreated intraocular pressure (IOP), worst mean deviation and greatest vertical cup disc ratio of the worst eye. The iris features were broadly classified into three groups: those with normal iris crypts (NIC), those with prominent iris crypts (PIC) and those with absence of iris crypts. The gonio photographs were graded as normal appearing angle or those with angle dysgenesis in the form of a featureless angle, one with a high iris insertion and an angle with prominent iris processes. Using a hierarchical clustering model and a two-way cluster analysis, the distribution of clusters of JOAG was analysed to obtain a classification of JOAG subtypes. Results The four major clusters identified were: Cluster 1 with NIC and normal angles had the lowest untreated IOP and higher age of onset among all clusters. Cluster 2 with NIC and featureless angle was found to be associated with earliest age of onset. Cluster 3 had NIC and either a high iris insertion or prominent iris processes. Cluster 4 was a heterogeneous cluster with maximum number of patients in a group comprising of those with PIC and high iris insertion. Conclusions Cluster analysis extracted four subgroups of the JOAG phenotype that have clinical and prognostic significance and can potentially be helpful while evaluating these patients in the clinics.
... "freckles") abgrenzen. Sie haben sogar eine Prävalenz von >50 % [3,7]. Bei letztgenannten handelt es sich um normal verteilte Melanozyten des vorderen Irisstromas, die lediglich vermehrt Melanin eingelagert haben, nicht jedoch um eine melanozytäre Hyperplasie. ...
Article
Background The differentiation of iridic space-occupying lesions represents a regularly reoccurring diagnostic challenge. Objective This article presents an overview of the epidemiological data and describes the diagnostic procedure for iris tumors. Material and methods The article provides a review of the literature from PubMed and own clinical results. Results Melanocytic lesions comprise the vast majority of all iris tumors and include nevi and melanomas. Slit lamp biomicroscopy with standardized photography reveals two-dimensional planar tumor growth over time, which is the only recognized clinical surrogate finding for a malignant event. Ultrasound biomicroscopy (UBM) is additionally obligatory because it is the only method which enables documentation of the extent of tumor penetration, ciliary body involvement and internal structure of iris tumors. Conclusion Serial slit lamp and UBM examinations with reproducible pupillary diameters are indispensable for the differentiation of cystic, solid and tumor-simulating lesions and for the detection of malignant transformation in iris tumors.
... In 1961, using a special flash illumination and high magnification photographic system, Donaldson was able to detect a prevalence of Brushfield spots and/or iris speckling in 77% of individuals with Down syndrome with brown irides, and a prevalence of Wölfflin nodules in 13% of controls with brown irides 11 , both figures remarkably close to what we were able to disclose using infrared wavelengths. Falls also believed the specific iris features to be less conspicuous in darker eyes 12 , likely hidden by the higher density and number of melanin granules in the anterior-border layer of darker colored irides 13,14 . ...
... Melanin is relatively transparent to infrared wavelengths 15 and such easily tolerated iris illumination has been employed for identity screening and confirmation in the general population 16,17 , as well as for iris-crypt-based video-oculography to measure ocular torsion 18 .Although suggested previously 13 , it had not been applied as a means to investigate the iris itself such as for the visualization and study of Wöllflin nodules or Brushfield spots. In those with lightly colored eyes with iris spots or nodules already visible in standard white light, we did not detect additional spots or nodules using near-infrared wavelengths. ...
Article
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Abstract Wölfflin nodules and Brushfield spots were described essentially in light colored irides. The purpose of our study is to determine if these iris features are also present in dark irides, hidden by melanin granules of the anterior leaf of the iris. We examined iris images, taken with standard visible white, as well as with near-infrared light of children with Down syndrome and without. Using white light, Brushfield spots were seen in 21% of children with Down syndrome, and Wölfflin nodules in 12% of controls (p
... There exists textural differences in the iris between races as well. Edwards et al. [26] examined images of irides in the visible spectrum from 3 separate populations: South Asian, East Asian and European. Europeans were found to have a higher grade 5 of Fuchs' crypts, more pigment spots, more extended contraction furrows, and more extended Wolfflin nodules than East Asians [26]. ...
... Edwards et al. [26] examined images of irides in the visible spectrum from 3 separate populations: South Asian, East Asian and European. Europeans were found to have a higher grade 5 of Fuchs' crypts, more pigment spots, more extended contraction furrows, and more extended Wolfflin nodules than East Asians [26]. East Asians were found to have a lower grade of Fuchs' crypts than both Europeans and South Asians. ...
... East Asians were found to have a lower grade of Fuchs' crypts than both Europeans and South Asians. Europeans had the largest iris width, followed by South Asians, and then by East Asians [26]. As for eye color, East Asians had the darkest while Europeans had the lightest. ...
Article
Recent research has explored the possibility of automatically deducing information such as gender, age and race of an individual from their biometric data. While the face modality has been extensively studied in this regard, the iris modality less so. In this paper, we first review the medical literature to establish a biological basis for extracting gender and race cues from the iris. Then, we demonstrate that it is possible to use simple texture descriptors, like BSIF (Binarized Statistical Image Feature) and LBP (Local Binary Patterns), to extract gender and race attributes from an NIR ocular image used in a typical iris recognition system. The proposed method predicts gender and race from a single eye image with an accuracy of 86% and 90%, respectively. In addition, the following analysis are conducted: (a) the role of different parts of the ocular region on attribute prediction; (b) the influence of gender on race prediction, and vice-versa; (c) the impact of eye color on gender and race prediction; (d) the impact of image blur on gender and race prediction; (e) the generalizability of the method across different datasets; and (f) the consistency of prediction performance across the left and right eyes.
... Although a previous study [16] found that age and gender have a significant effect on iris color, the lightness and color of the iris are significantly correlated with age [11]. This indicates that the lightness and color of the iris depend on other permanent factors or the race of individuals rather than differences, as reported by Edwards et al. [17], and that CIELAB values of the iris are simply due to age. In a study by Kim et al. [11], a higher L* value of the iris was correlated with a higher a*b* value of the iris, indicating the iris melanin constitution of color, especially since it depends on the hue. ...
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Objectives The iris is the part of the eye that is colored, and it is an important feature in making an artificial eye. To address the lack of information about the brown Korean irises, we classified the colors and patterns of the irises of 100 Korean eyes. Methods The iris colors were extracted from 100 different digital photographs of each eye using K-mean clustering image analysis. The RGB data of the extracted colors were converted to CIELAB color space data and analyzed to determine the representative color of the iris in each photograph. The color differences were calculated to form groups of similar colors by matching the 100 samples into several groups with minimum color differences among them. The average hue value for each group was calculated, and the corresponding representative color was selected from 2 to 3 colors in one group. Results The iris colors were classified into seven brown color groups with 2 to 3 colors in each group. The coloration of Koreans' eyes appears to vary in a similar hue with differences in chroma and lightness. In addition, the iris patterns were classified into three basic patterns, namely, crown, sunshine, and flower, as well as three complex patterns that are mixtures of two basic patterns. Conclusions We classified Korean iris colors and patterns for application in the design of artificial eyes.