Iris Contour Research Articles

Eyes gaze detection based on multiprocess of ratio parameters for smart wheelchair menu selection in different screen size

Smart wheelchairs support paralysis disability people, especially paralysis of the hands and feet. Paralysis disability cannot operate menu selection with a touch screen. This research proposes a menu selection to select features in a smart wheelchair using the eye’s gaze and execute the menu by blinking the left eye. Multiprocess of ratio parameter is the methodology used and expanded in this research. The proposed method compared the ratio between the midpoint on the iris contour and registered midpoint on the selection step. This research is conducted under two conditions: the screen size being started in 14 and 17 inches. This research resulted in 91.48% and 90.68% accuracy in 14 and 17-inch screens for users without glasses. Meanwhile, 89.55% and 86.99% were obtained for wearing glasses users. The experiments were conducted where the position of a user is 30–39, 40–49, and 50–59 cm from the camera.

Finding Stars From Fireworks: Improving Non-Cooperative Iris Tracking

We revisit the problem of iris tracking with RGB cameras, aiming to obtain iris contours from captured images of eyes. We find the reason that limits the performance of the state-of-the-art method in more general non-cooperative environments, which prohibits a wider adoption of this useful technique in practice. We believe that because the iris boundary could be inherently unclear and blocked, as its pixels occupy only an extremely limited percentage of those on the entire image of the eye, similar to the stars hidden in fireworks, we should not treat the boundary pixels as one class to conduct end-to-end recognition directly. Thus, we propose to learn features from iris and sclera regions first, and then leverage entropy to sketch the thin and sharp iris boundary pixels, where we can trace more precise parameterized iris contours. In this work, we also collect a new dataset by smartphone with 22 K images of eyes from video clips. We annotate a subset of 2 K images, so that label propagation can be applied to further enhance the system performance. Extensive experiments over both public and our own datasets show that our method outperforms the state-of-the-art method. The results also indicate that our method can improve the coarsely labeled data to enhance the iris contour’s accuracy and support the downstream application better than the prior method.

Novel ophthalmic findings and deep phenotyping in Williams-Beuren syndrome

Background/AimsTo characterise the ocular manifestations of Williams-Beuren syndrome (WBS) and compare these to patients with isolated elastin mediated supravalvular aortic stenosis (SVAS).MethodsFifty-seven patients with a diagnosis of WBS and five...

Multitask deep active contour-based iris segmentation for off-angle iris images

Iris recognition has been considered as a secure and reliable biometric technology. However, iris images are prone to off-angle or are partially occluded when captured with fewer user cooperations. As a consequence, iris recognition especially iris segmentation suffers a serious performance drop. To solve this problem, we propose a multitask deep active contour model for off-angle iris image segmentation. Specifically, the proposed approach combines the coarse and fine localization results. The coarse localization detects the approximate position of the iris area and further initializes the iris contours through a series of robust preprocessing operations. Then, iris contours are represented by 40 ordered isometric sampling polar points and thus their corresponding offset vectors are regressed via a convolutional neural network for multiple times to obtain the precise inner and outer boundaries of the iris. Next, the predicted iris boundary results are regarded as a constraint to limit the segmentation range of noise-free iris mask. Besides, an efficient channel attention module is introduced in the mask prediction to make the network focus on the valid iris region. A differentiable, fast, and efficient SoftPool operation is also used in place of traditional pooling to keep more details for more accurate pixel classification. Finally, the proposed iris segmentation approach is combined with off-the-shelf iris feature extraction models including traditional OM and deep learning-based FeatNet for iris recognition. The experimental results on two NIR datasets CASIA-Iris-off-angle, CASIA-Iris-Africa, and a VIS dataset SBVPI show that the proposed approach achieves a significant performance improvement in the segmentation and recognition for both regular and off-angle iris images.

Case Report: The efficacy of early phacoemulsification in the intraocular pressure control in primary angle closure glaucoma associated with cataract in a young female

Glaucoma is a leading cause of irreversible blindness worldwide. Among different types of glaucoma, irreversible bilateral visual impairment is more common in primary angle closure glaucoma (PACG) patients. PACG and cataract often coexist and are both more prevalent among the elderly population, being rare in children and young adults. Here, we discuss the case of a 39-year-old Caucasian woman with unilateral PACG associated with cataract. The patient presented with a several-day history of left sided headache, decreased and blurred vision as well as pain and redness of the left eye (LE). She reported similar episodes in the previous year. Visual acuity (VA) of the LE was limited to counting fingers and intra-ocular pressure (IOP) of the LE was 42 mmHg. Anterior segment examination of the LE revealed: edematous cornea, a peripheral anterior chamber depth corresponding to Van Herick’s grade 0, mid-dilated pupil and lens opacities with visible glaukomflecken. Gonioscopic evaluation revealed iridotrabecular contact for 360º, no visible angle structures and a flat–mild convex iris contour. Spectral domain optical coherence tomography suggested only a thinning of neuro-retinal rim at the lower pole. Following treatment of the initial symptoms, phacoemulsification with intra-ocular lens implant was performed. IOP improved and no IOP-lowering medication was required. The patient was monitored for VA, IOP, field of vision changes, and optic disc evaluation every six months for 2 years and no glaucomatous change occurred. The patient also denied ocular symptoms during this period. This case supports the effectiveness of early phacoemulsification in the IOP control in patients with PACG.

Iris segmentation for non-ideal Iris biometric systems

At present, iris recognition systems are highly demanded for covert applications such as monitoring terrorist activities at public places, walk-through portals, smart cities, etc. In general, these systems use image acquisition setups working under relaxed conditions due to which the quality of acquired images is usually poor. For example, images may contain non-uniform illumination, defocus, blur, reflections and eyelids/eyelashes occlusion. Due to these issues, most contemporary iris segmentation schemes do not perform well. In addition, precise localization of eyes in human face images is also a challenging task. No doubt, wrong localization of eyes may certainly lead to failure of the subsequent system modules. To contribute in this regard, this study offers a robust scheme that functions as follows. First, it supplements the Viola-Jones algorithm with the geometrical information of human face to segment eyes. Next, it preprocesses an eyeimage to enhance its contrast, suppress reflections, smooth down spiky gray-level variations if any and marks a circular region-of-interest (ROI) containing iris. Then, it applies an iterative scheme involving Hough transform to segment iris. Finally, it extracts non-circular iris contours using an effective scheme centered on the Lagrange interpolating polynomial. This scheme has shown improved performance on public face-dataset (CASIA-IrisV4-Distance) and two iris datasets, MMU V1.0 and IITD V1.0. On average, it attained 97.97% accuracy rate on these databases.

Study of anterior chamber angle: Gonioscopy and ultrasound biomicroscopy

Gonioscopy is the widely used technique of grading and evaluating the anterior chamber angle in current glaucoma evaluation practice. The grading of angle and open angle or narrow angle classification with gonioscopy is fairly accurate when done by an experienced ophthalmologist. In recent years, UBM and anterior segment OCT are advanced and in depth imaging tools for the anterior segment evaluation and accurate angle measurements. In our study, we have included 200 eyes for anterior chamber angle grading with gonioscopy and UBM and results are compared. Our study shows that some amount of estimation of angle depth by gonioscopy is overestimated in nearly closed and grade 1 angles. Estimation of grades 2 and 3 is nearly accurate with gonioscopy and comparable to UBM angle grading. Over diagnosis of occludable angles with gonioscopy which can be explained due to iris contour, inter-observer reliability or limitation to examine far periphery of the angle and this can be overcome by UBM examination. UBM provides accurate anterior chamber angle in degrees, peripheral iris configuration details and quantification of measurements is possible.

I-SOCIAL-DB: A labeled database of images collected from websites and social media for Iris recognition

People upload daily a huge number of portrait face pictures on websites and social media, which can be processed using biometric systems based on the face characteristics to perform an automatic recognition of the individuals. However, the performance of face recognition approaches can be limited by negative factors as aging, occlusions, rotations, and uncontrolled expressions. Nevertheless, the constantly increasing quality and resolution of the portrait pictures uploaded on websites and social media could permit to overcome these problems and improve the robustness of biometric recognition methods by enabling the analysis of additional traits, like the iris. To point the attention of the research community to the possible use of iris-based recognition techniques for images uploaded on websites and social media, we present a public image dataset called I-SOCIAL-DB (Iris Social Database). This dataset is composed of 3,286 ocular regions, extracted from 1,643 high-resolution face images of 400 individuals, collected from public websites. For each ocular region, a human expert extracted the coordinates of the circles approximating the inner and outer iris boundaries and performed a pixelwise segmentation of the iris contours, occlusions, and reflections. This dataset is the first collection of ocular images from public websites and social media, and one of the biggest collections of manually segmented ocular images in the literature. In this paper, we also present a qualitative analysis of the samples, a set of testing protocols and figures of merit, and benchmark results achieved using publicly available iris segmentation and recognition algorithms. We hope that this initiative can give a new test tool to the biometric research community, aiming to stimulate new studies in this challenging research field.

A robust iris localization scheme for the iris recognition

Due to current security situations around the globe, iris biometric technology is highly preferred for both overt and covert applications. A typical iris biometric system includes image acquisition, iris segmentation, features extraction, and matching and recognition modules. Amongst these modules, iris segmentation plays a decisive role because it segments the valid iris part in an input eyeimage. It includes two tasks: iris localization and noise (e.g., eyelids) removal. Notably, the overall performance of an iris biometric system strongly relies on the iris localization task, because it demarcates the actual iris contours. Some contemporary iris localization schemes search over a three-dimensional (3D) space while marking iris boundaries, which is a time-consuming process if not optimized properly. Besides, some schemes also resort to the fixed and/or crude thresholding-based techniques for pupil localization. Notably, such schemes may perform poorly if image data do not maintain quality. To address these issues, this study proposes a robust iris localization scheme maintaining both speed and accuracy. It includes preprocessing the input eyeimage using an order statistic-filter and the bilinear interpolation scheme, extracting an adaptive threshold using the image’s histogram, processing binary image via the morphological operators, extracting pupil’s center and radius based on the centroid and geometry concepts, marking iris outer boundary using the Circular Hough transform (CHT) and refining coarse iris boundaries through the Fourier series. The proposed scheme exhibits relatively better experimental results compared with some contemporary iris localization schemes on the public iris databases: IITD V1.0, CASIA-Iris-Interval and MMU V1.0.

Case Report: The efficacy of early phacoemulsification in the intraocular pressure control in primary angle closure glaucoma associated with cataract in a young female

Glaucoma is a leading cause of irreversible blindness in the world, second only to cataract. Among different types of glaucoma, irreversible bilateral visual impairment is more common in primary angle closure glaucoma (PACG) patients. PACG and cataract often coexist and are both more prevalent among the elderly population, being rare in children and young adults. Here, we discuss the case of a 39-year-old Caucasian woman with unilateral PACG associated with cataract. The patient presented with a several-day history of left sided headache, decreased and blurred vision as well as pain and redness of the left eye (LE). She reported similar episodes in the previous year. Visual acuity (VA) of the LE was limited to counting fingers and intra-ocular pressure (IOP) of the LE was 42 mmHg. Anterior segment examination of the LE revealed: edematous cornea, a peripheral anterior chamber depth corresponding to Van Herick’s grade 0, mid-dilated pupil and lens opacities with visible glaukomflecken. Gonioscopic evaluation revealed iridotrabecular contact for 360º, no visible angle structures and a flat–mild convex iris contour. The digital image of the optic disc suggested only a thinning of neuro-retinal rim at the lower pole. Following treatment of the initial symptoms, phacoemulsification with intra-ocular lens implant was performed. IOP improved and no IOP-lowering medication was required. The patient was monitored for VA, IOP, field of vision changes, and optic disc evaluation every six months for 2 years and no glaucomatous change occurred. The patient also denied ocular symptoms during this period. This case supports the effectiveness of early phacoemulsification in the IOP control in patients with PACG.

Remote Grading of the Anterior Chamber Angle Using Goniophotographs and Optical Coherence Tomography: Implications for Telemedicine or Virtual Clinics.

PurposeTo evaluate the agreement and accuracy of grading goniophotographs and anterior segment optical coherence tomography (AS-OCT) results for assessment of the anterior chamber angle, and elicit factors driving concordance between perceived grade and ground truth.MethodsThree clinicians evaluated the goniophotographs and AS-OCT results of 75 patients. Graders' impressions of the angle grade, trabecular pigmentation, and iris contour were compared with the ground truth gonioscopic examination result when physically performed by a senior optometrist. Percentage agreement and kappa statistics were calculated. Binary logistic regression was used to elicit factors for accurate grading.ResultsExact angle matches and binary (open or closed) evaluations were above guessing rate for all graders. There was a systematic bias toward underestimating the angle structure across all graders, especially at the superior angle, by approximately 1 ordinal unit. Kappa statistics showed fair-moderate agreement for exact (0.387–0.520) and binary (0.347–0.520) angle evaluations. Agreement was unchanged when using a multimodal approach (0.373–0.523). Factors driving concordance were primarily related to the extremes of the anterior chamber angle configuration (shallow or deep structures, and iris contour). However, prediction models did not fully explain the levels of concordance with the ground truth (maximum R2 amongst models 0.177).ConclusionsAlthough moderate agreement between graders and ground truth could be obtained under binary evaluations, angle grades were generally underestimated. Factors affecting concordance were primarily the extremes of the ground truth angle and iris contour.Translational RelevanceWe highlight factors affecting accuracy of grading goniophotography and AS-OCT images of the anterior chamber angle.

Gaze estimation using a head-mounted single full-view camera

We present a gaze estimation method for a head-mounted full-view egocentric camera that can capture egocentric video together with users’ gaze cues. While the conventional gaze recording device has two cameras, an eye camera and a scene camera, the proposed gaze recording device has only a single spherical camera with a full field of view. To determine the point of gaze on full-view images, we present an eye-model-based gaze estimation method by means of three-dimensional iris projection. First, an eye model is built according to the precalibration process of an eyeball center and the eyeball biological parameters; then, we express the 3D iris contour in the eye model and project it back to the spherical camera model. Since 2D iris contours can be detected directly on images and can also be expressed under the spherical model, the relationship between the 3D iris contour and the 2D iris contour can be found. By solving this problem, the gaze direction under the camera model is determined; subsequently, the point of gaze on the images can be inferred. Since in the proposed method, a single spherical camera can play the role of the conventional two cameras, not only do the proposed method results have a simpler system structure but also the cumbersome operation of the calibration for the conventional two-camera gaze measurement devices becomes unnecessary. The effectiveness of the proposed method is shown by the experimental results.

Non-circular iris contours localization in the visible wavelength eye images

Contemporary iris localization schemes perform well for ideal eye images generally acquired using near infrared (NIR) illumination, but perform poorly for non-ideal eye images acquired using Visible Wavelength (VW) illumination. Non-ideal eye images contain noise such as non-uniform illumination, defocus, etc. This study proposes a reliable iris localization algorithm, in particular for VW eye images. First, it suppresses light reflections and sharp intensity variations in the Red-component of input color eye image. Next, it marks a set of potential pixels (ROIpixels) suitable as the iris center's candidates. Using ROIpixels, it localizes potential iris location using a hybrid of Integro-differential operator (IDO) and image intensity. Then, it reuses IDO and iris/pupil's geometry to localize pupil within iris. Finally, it uses the Fourier series based scheme to regularize iris contours. Experimental results obtained on UBIRIS V1.0, MMU V1.0, and IITD V1.0 iris databases demonstrate its superior performance compared with contemporary schemes.

Estimating 3D Gaze Directions Using Unlabeled Eye Images via Synthetic Iris Appearance Fitting

Estimating three-dimensional (3D) human eye gaze by capturing a single eye image without active illumination is challenging. Although the elliptical iris shape provides a useful cue, existing methods face difficulties in ellipse fitting due to unreliable iris contour detection. These methods may fail frequently especially with low resolution eye images. In this paper, we propose a synthetic iris appearance fitting (SIAF) method that is model-driven to compute 3D gaze direction from iris shape. Instead of fitting an ellipse based on exactly detected iris contour, our method first synthesizes a set of physically possible iris appearances and then optimizes inside this synthetic space to find the best solution to explain the captured eye image. In this way, the solution is highly constrained and guaranteed to be physically feasible. In addition, the proposed advanced image analysis techniques also help the SIAF method be robust to the unreliable iris contour detection. Furthermore, with multiple eye images, we propose a SIAF-joint method that can further reduce the gaze error by half, and it also resolves the binary ambiguity which is inevitable in conventional methods based on simple ellipse fitting.

Establishing Age-Adjusted Reference Ranges for Iris-Related Parameters in Open Angle Eyes with Anterior Segment Optical Coherence Tomography.

PurposeDefine criteria for iris-related parameters in an adult open angle population as measured with swept source Fourier domain anterior segment optical coherence tomography (ASOCT).MethodsNinety-eight eyes of 98 participants with open angles were included and stratified into 5 age groups (18–35, 36–45, 46–55, 56–65, and 66–79 years). ASOCT scans with 3D mode angle analysis were taken with the CASIA SS-1000 (Tomey Corporation, Nagoya, Japan) and analyzed using the Anterior Chamber Analysis and Interpretation software. Anterior iris surface length (AISL), length of scleral spur landmark (SSL) to pupillary margin (SSL-to-PM), iris contour ratio (ICR = AISL/SSL-to-PM), pupil radius, radius of iris centroid (RICe), and iris volume were measured. Outcome variables were summarized for all eyes and age groups, and mean values among age groups were compared using one-way analysis of variance. Stepwise regression analysis was used to investigate demographic and ocular characteristic factors that affected each iris-related parameter.ResultsMean (±SD) values were 2.24 mm (±0.46), 4.06 mm (±0.27), 3.65 mm (±0.48), 4.16 mm (±0.47), 1.14 (±0.04), 1.51 mm2 (±0.23), and 38.42 μL (±4.91) for pupillary radius, RICe, SSL-to-PM, AISL, ICR, iris cross-sectional area, and iris volume, respectively. Both pupillary radius (P = 0.002) and RICe (P = 0.027) decreased with age, while SSL-to-PM (P = 0.002) and AISL increased with age (P = 0.001). ICR (P = 0.54) and iris volume (P = 0.49) were not affected by age.ConclusionThis study establishes reference values for iris-related parameters in an adult open angle population, which will be useful for future studies examining the role of iris changes in pathologic states.

Angle Closure Associated With a Cobblestone Iris Configuration

The purpose of the study was to report a patient with primary angle closure associated with a different nonpupillary block mechanism in which an abnormally thick peripheral iris assumes a cross-sectional shape resembling a cobblestone. This is a case report focussing on clinical and imaging description. Slit-lamp biomicroscopy revealed patent laser peripheral iridotomies OU. The anterior chamber was relatively deep in the center but 360 degrees narrow at the periphery, associated with an abnormally elevated iris contour OU. On dark-room gonioscopy, the angles were occludable with few areas of peripheral anterior synechiae. Anterior segment-adapted spectral domain-optical coherence tomography revealed an unusual iris profile. Despite a flat contour and normal thickness until the mid-periphery, the iris assumed a rectangular cross-sectional shape (resembling a cobblestone) with an abnormal increase in its thickness in the periphery (360 degrees OU). Ultrasound biomicroscopy imaging showed a normal ciliary sulcus and ciliary body configuration, revealing no cysts at 360 degrees. Definitive relief of appositional angle closure was achieved with laser peripheral iridoplasty OU. This unusual anatomic condition of the peripheral iris, which has different characteristics when compared with ordinary cases of thick peripheral iris roll, may lead to angle closure and intraocular pressure elevation despite a patent iridotomy. Clinicians should be aware of this anatomic condition whenever dealing with cases of angle closure.

Contribution of Different Anatomical and Physiologic Factors to Iris Contour and Anterior Chamber Angle Changes During Pupil Dilation: Theoretical Analysis

To investigate the contribution of three anatomical and physiologic factors (dilator thickness, dynamic pupillary block, and iris compressibility) to changes in iris configuration and anterior chamber angle during pupil dilation. A MATHEMATICAL MODEL OF THE ANTERIOR SEGMENT BASED ON THE AVERAGE VALUES OF OCULAR DIMENSIONS WAS DEVELOPED TO SIMULATE PUPIL DILATION. TO CHANGE THE PUPIL DIAMETER FROM 3.0 TO 5.4 MM IN 10 SECONDS, ACTIVE DILATOR CONTRACTION WAS APPLIED BY IMPOSING STRESS IN THE DILATOR REGION. THREE SETS OF PARAMETERS WERE VARIED IN THE SIMULATIONS: (1) a thin (4 μm, 1% of full thickness) versus a thick dilator (covering the full thickness iris) to quantify the effects of dilator anatomy, (2) in the presence (+PB) versus absence of pupillary block (-PB) to quantify the effect of dynamic motion of aqueous humor from the posterior to the anterior chamber, and (3) a compressible versus an incompressible iris to quantify the effects of iris volume change. Changes in the apparent iris-lens contact and angle open distance (AOD500) were calculated for each case. The thin case predicted a significant increase (average 700%) in iris curvature compared with the thick case (average 70%), showing that the anatomy of dilator plays an important role in iris deformation during dilation. In the presence of pupillary block (+PB), AOD500 decreased 25% and 36% for the compressible and incompressible iris, respectively. Iris bowing during dilation was driven primarily by posterior location of the dilator muscle and by dynamic pupillary block, but the effect of pupillary block was not as large as that of the dilator anatomy according to the quantified values of AOD500. Incompressibility of the iris, in contrast, had a relatively small effect on iris curvature but a large effect on AOD500; thus, we conclude that all three effects are important.

Increased iris–lens contact following spontaneous blinking: Mathematical modeling

The purpose of this work was to study in silico how iris root rotation due to spontaneous blinking alters the iris contour. An axisymmetric finite-element model of the anterior segment was developed that included changes in the iris contour and the aqueous humor flow. The model geometry was based on average values of ocular dimensions. Blinking was modeled by rotating the iris root posteriorly and returning it back to the anterior. Simulations with maximum rotations of 2°, 4°, 6°, and 8° were performed. The iris–lens contact distance and the pressure difference between the posterior and anterior chambers were calculated. When the peak iris root rotation was 2°, the maximum iris–lens contact increased gradually from 0.28 to 0.34mm within eight blinks. When the iris root was rotated by 6° and 8°, the pressure difference between the posterior and anterior chambers dropped from a positive value (1.23Pa) to negative values (−0.86 and −1.93Pa) indicating the presence of reverse pupillary block. Apparent iris-lens contact increased with steady blinking, and the increase became more pronounced as posterior rotation increased. We conclude that repeated iris root rotation caused by blinking could maintain the iris in a posterior position under normal circumstances, which would then lead to the clinically observed anterior drift of the iris when blinking is prevented.

Daugman’s Algorithm Enhancement for Iris Localization

Iris localization is considered the most difficult part in iris identification algorithms because it defines the inner and outer boundaries of iris region used for feature analysis. Several researches were taken in the subject of iris finding and segmentation. The main objective here is to remove any non-useful information, namely the pupil segment and the part outside the iris. Duda and Hart used Hough transforms to detect the contours and curves. Daugman proposed an integro-differential operator to find both the pupil and the iris contour. Daugman’s method is claimed to be the most efficient one. This paper proposes an implementation for Daugman's algorithm, which was found incompatible with visible light illuminated images. Then this paper proposes algorithm enhancement for solving this problem.

A Multi-Gesture Interaction System Using a 3-D Iris Disk Model for Gaze Estimation and an Active Appearance Model for 3-D Hand Pointing

In this paper, we present a vision-based human-computer interaction system, which integrates control components using multiple gestures, including eye gaze, head pose, hand pointing, and mouth motions. To track head, eye, and mouth movements, we present a two-camera system that detects the face from a fixed, wide-angle camera, estimates a rough location for the eye region using an eye detector based on topographic features, and directs another active pan-tilt-zoom camera to focus in on this eye region. We also propose a novel eye gaze estimation approach for point-of-regard (POR) tracking on a viewing screen. To allow for greater head pose freedom, we developed a new calibration approach to find the 3-D eyeball location, eyeball radius, and fovea position. Moreover, in order to get the optical axis, we create a 3-D iris disk by mapping both the iris center and iris contour points to the eyeball sphere. We then rotate the fovea accordingly and compute the final, visual axis gaze direction. This part of the system permits natural, non-intrusive, pose-invariant POR estimation from a distance without resorting to infrared or complex hardware setups. We also propose and integrate a two-camera hand pointing estimation algorithm for hand gesture tracking in 3-D from a distance. The algorithms of gaze pointing and hand finger pointing are evaluated individually, and the feasibility of the entire system is validated through two interactive information visualization applications.