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Turuwhenua J, LinTun Z, Norouzifard M, Edmonds M, Findlay R, Black J, Thompson B. Automated visual acuity estimation by optokinetic nystagmus using a stepped sweep stimulus. Ophthalmic Physiol Opt 2024; 44:1500-1512. [PMID: 39258616 DOI: 10.1111/opo.13391] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2024] [Revised: 08/22/2024] [Accepted: 08/27/2024] [Indexed: 09/12/2024]
Abstract
PURPOSE To describe an automatic system for objective measurement of visual acuity (VA) using optokinetic nystagmus (OKN). This pilot study tested the system's sensitivity and specificity for detecting reduced VA in healthy adults by comparing VA-OKN to VA with an Early Treatment of Diabetic Retinopathy Study (ETDRS) chart (VA-ETDRS). METHODS Adult participants (age 30 ± 12 years) with either reduced VA (n = 11, VA-ETDRS > 0.20 logMAR) or normal VA (n = 12, VA-ETDRS ≤ 0.20 logMAR) completed monocular VA-OKN measurements in each eye. The VA-OKN stimulus was an array of drifting (5°/s) vanishing discs presented in descending/ascending size order (0.00-1.00 logMAR in 0.10 steps). The stimulus was stepped every 2 s, and 10 sweeps were shown per eye (five ascending and five descending). Eye-tracking data determined when OKN activity ceased (descending sweep) or began (ascending sweep), which was used to determine VA-OKN for each sweep. The estimates were averaged across sweeps to produce an automated VA-OKN. The automated sweeps were then provided in randomised order to a reviewer blinded to the VA-ETDRS findings who determined a final VA-OKN for an eye. RESULTS A single randomly selected eye from each observer was used for analysis. The sensitivity and specificity of VA-OKN using the same 0.20 logMAR threshold as VA-ETDRS was 100%. Comparisons between the VA-OKN and VA-ETDRS measures were made for participants in the reduced VA group. There was no significant difference between VA-OKN and VA-ETDRS (p = 0.55) and the two measures produced comparable values (r2 = 0.84, 95% limits of agreement = 0.19 logMAR, intra-class correlation coefficient = 0.90 [95% CI:0.68-0.97]). CONCLUSIONS Visual acuity using optokinetic nystagmus correctly identified a VA deficit in adults and for those with a VA deficit, VA-OKN was strongly correlated with the gold-standard clinical measure of VA. OKN is a promising method which has the potential for use in cognitively impaired adults and pre-verbal children.
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Affiliation(s)
- Jason Turuwhenua
- Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand
- School of Optometry and Vision Science, The University of Auckland, Auckland, New Zealand
| | - Zaw LinTun
- Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand
| | - Mohammad Norouzifard
- Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand
| | | | - Rebecca Findlay
- School of Optometry and Vision Science, The University of Auckland, Auckland, New Zealand
| | - Joanna Black
- School of Optometry and Vision Science, The University of Auckland, Auckland, New Zealand
| | - Benjamin Thompson
- School of Optometry and Vision Science, The University of Auckland, Auckland, New Zealand
- School of Optometry and Vision Science, The University of Waterloo, Waterloo, Ontario, Canada
- Centre for Eye and Vision Research, Shatin, Hong Kong
- Liggins Institute, The University of Auckland, Auckland, New Zealand
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Sekar A, Panouillères MTN, Kaski D. Detecting Abnormal Eye Movements in Patients with Neurodegenerative Diseases - Current Insights. Eye Brain 2024; 16:3-16. [PMID: 38617403 PMCID: PMC11015840 DOI: 10.2147/eb.s384769] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2023] [Accepted: 03/23/2024] [Indexed: 04/16/2024] Open
Abstract
This review delineates the ocular motor disturbances across a spectrum of neurodegenerative disorders, including Alzheimer's Disease (AD) and related disorders (ADRD), Parkinson's Disease (PD), atypical parkinsonism, and others, leveraging advancements in eye-tracking technology for enhanced diagnostic precision. We delve into the different classes of eye movements, their clinical assessment, and specific abnormalities manifesting in these diseases, highlighting the nuanced differences and shared patterns. For instance, AD and ADRD are characterized by increased saccadic latencies and instability in fixation, while PD features saccadic hypometria and mild smooth pursuit impairments. Atypical parkinsonism, notably Progressive Supranuclear Palsy (PSP) and Corticobasal Syndrome (CBS), presents with distinct ocular motor signatures such as vertical supranuclear gaze palsy and saccadic apraxia, respectively. Our review underscores the diagnostic value of eye movement analysis in differentiating between these disorders and also posits the existence of underlying common pathological mechanisms. We discuss how eye movements have potential as biomarkers for neurodegenerative diseases but also some of the existing limitations.
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Affiliation(s)
- Akila Sekar
- SENSE Research Unit, Department of Clinical and Movement Neurosciences, UCL Queen Square Institute of Neurology, London, UK
| | - Muriel T N Panouillères
- NeuroClues, Ottignies-Louvain-la-Neuve, Belgium
- CIAMS, Université Paris-Saclay, Orsay, France
| | - Diego Kaski
- SENSE Research Unit, Department of Clinical and Movement Neurosciences, UCL Queen Square Institute of Neurology, London, UK
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Min X, Rehman FU, Jing W, Nan C, Cheng C, Yu S. Preliminary study on the computer-based optokinetic nystagmus analyzer to detect the visual acuity of preschool children. Indian J Ophthalmol 2024; 72:S162-S166. [PMID: 38271412 DOI: 10.4103/ijo.ijo_2683_23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2023] [Accepted: 12/08/2023] [Indexed: 01/27/2024] Open
Abstract
The purpose of this study is to examine the viability, precision, and consistency of a computer-based optokinetic nystagmus analyzer (nystagmus meter) for diagnosing eyesight in preschoolers. A total of 59 subjects who could pass the log of minimum angle of resolution (LogMAR) visual acuity chart were divided into three groups by age, 4-, 5-, and 6-year-old groups, and their visual acuity was tested with nystagmus meter. The percentage of children in each age group that could be detected by nystagmus was recorded along with the differences between these groups. The correlation between the test results from the two methods was found for each age group using the correlation coefficient method. Repeated measurements were used to assess the two visual acuity values of the measured nystagmus, and the repeatability of the two measurement techniques for different age groups was compared. The overall measurability of the visual acuity detected by nystagmus was 93.22%, and the measurability of the 4-, 5-, and 6-year-old groups was 90%, 95%, and 94.74%, respectively. There was no statistically significant difference in the measurability of subjects among all age groups (P = 1.0). The outcomes of the LogMAR visual acuity chart had a negative correlation with the visual acuity measured by the nystagmus meter. The overall correlation coefficient R value was -0.80, and the correlation coefficient R value of the 4-, 5-, and 6-year-old groups was -0.79, -0.76, and -0.87, respectively. The nystagmus meter has good feasibility, accuracy, and stability in visual acuity testing and can be used for visual acuity testing in children.
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Affiliation(s)
- Xia Min
- Department of Ophthalmology, Weihai Central Hospital, Weihai, Shandong, China
| | - Faisal Ul Rehman
- Precision Medicine Center of Oncology, The Affiliated Hospital of Qingdao University, Qingdao University, Qingdao, Shangdong, China
- Department of Research and Development, Pengfengcheng Medical Technology, Qingdao, Shangdong, China
| | - Wang Jing
- Department of Ophthalmology, Weihai Central Hospital, Weihai, Shandong, China
| | - Chen Nan
- Department of Ophthalmology, Weihai Central Hospital, Weihai, Shandong, China
| | - Che Cheng
- Department of Management and Marketing, University of Petroleum Huadong, Qingdao, Shangdong, China
| | - Song Yu
- Department of Ophthalmology, Weihai Central Hospital, Weihai, Shandong, China
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Taore A, Lobo G, Turnbull PR, Dakin SC. Diagnosis of colour vision deficits using eye movements. Sci Rep 2022; 12:7734. [PMID: 35562176 PMCID: PMC9095692 DOI: 10.1038/s41598-022-11152-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Accepted: 04/08/2022] [Indexed: 11/09/2022] Open
Abstract
We set out to develop a simple objective test of functional colour vision based on eye movements made in response to moving patterns. We exploit the finding that while the motion of a colour-defined stimulus can be cancelled by adding a low-contrast luminance-defined stimulus moving in the opposite direction, the "equivalent luminance contrast" required for such cancellation is reduced when colour vision is abnormal. We used a consumer-grade infrared eye-tracker to measure eye movements made in response to coloured patterns drifting at different speeds. An automated analysis of these movements estimated individuals' red-green equiluminant point and their equivalent luminance contrast. We tested 34 participants: 23 colour vision normal controls, 9 deuteranomalous and 2 protanomalous individuals. We obtained reliable estimates of strength of directed eye movements (i.e. combined optokinetic and voluntary tracking) for stimuli moving at 16 deg/s and could use these data to classify participants' colour vision status with a sensitivity rate of 90.9% and a specificity rate of 91.3%. We conclude that an objective test of functional colour vision combining a motion-nulling technique with an automated analysis of eye movements can diagnose and assess the severity of protanopia and deuteranopia. The test places minimal demands on patients (who simply view a series of moving patterns for less than 90 s), requires modest operator expertise, and can be run on affordable hardware.
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Affiliation(s)
- Aryaman Taore
- School of Optometry and Vision Science, The University of Auckland, Auckland, New Zealand.
- New Zealand National Eye Centre, The University of Auckland, Auckland, New Zealand.
| | - Gabriel Lobo
- School of Optometry and Vision Science, The University of Auckland, Auckland, New Zealand
| | - Philip R Turnbull
- School of Optometry and Vision Science, The University of Auckland, Auckland, New Zealand
- New Zealand National Eye Centre, The University of Auckland, Auckland, New Zealand
| | - Steven C Dakin
- School of Optometry and Vision Science, The University of Auckland, Auckland, New Zealand
- New Zealand National Eye Centre, The University of Auckland, Auckland, New Zealand
- UCL Institute of Ophthalmology, University College London, London, UK
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Birch EE, Kelly KR, Wang J. Recent Advances in Screening and Treatment for Amblyopia. Ophthalmol Ther 2021; 10:815-830. [PMID: 34499336 PMCID: PMC8589941 DOI: 10.1007/s40123-021-00394-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Accepted: 08/26/2021] [Indexed: 11/30/2022] Open
Abstract
Amblyopia is the most common cause of monocular visual impairment in children, with a prevalence of 2-3%. Not only is visual acuity reduced in one eye but binocular vision is affected, fellow eye deficits may be present, eye-hand coordination and reading can be affected, and self-perception may be diminished. New technologies for preschool vision screening hold promise for accessible, early, and accurate detection of amblyopia. Together with recent advances in our theoretical understanding of amblyopia and technological advances in amblyopia treatment, we anticipate improved visual outcomes for children affected by this very common eye condition. This article is based on previously conducted studies and does not contain any new studies with human participants or animals performed by any of the authors.
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Affiliation(s)
- Eileen E Birch
- Retina Foundation of the Southwest, 9600 N. Central Expressway, Suite 200, Dallas, TX, 75231, USA.
- Department of Ophthalmology, University of Texas Southwestern Medical Center, Dallas, TX, USA.
| | - Krista R Kelly
- Retina Foundation of the Southwest, 9600 N. Central Expressway, Suite 200, Dallas, TX, 75231, USA
- Department of Ophthalmology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Jingyun Wang
- SUNY College of Optometry, State University of New York, New York, NY, USA
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Jaiseeli C, Raajan N. SLKOF: Subsampled Lucas-Kanade Optical Flow for Opto Kinetic Nystagmus detection. JOURNAL OF INTELLIGENT & FUZZY SYSTEMS 2021. [DOI: 10.3233/jifs-189849] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The neurological disorders are developed in adults due to reduced visual perception. Opto Kinetic Nystagmus (OKN) is a clinical method to detect visual perception. For objective measurements, a computational algorithm based OKN detection is preferable rather than clinical practice. In this paper, a memory-efficient Subsampled Lucas-Kanade Optical Flow (SLKOF) is proposed. The proposal employs the Subsampling of images for various levels. The proposal deals with the computation of OKN gain for different image Subsampling factors using the MATLAB platform. The experimental set up to observe OKN is done using computer-based rotation control of the drum through a stepper motor. The results are compared with the well established Lucas-Kanade (LK) method for Optical flow. It is observed that OKN gain corresponds to 1/4th of a subsampled image of the SLKOF method correlates with the LK method for the majority of the cases. This validation evidently elucidates that the proposal is computationally efficient.
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Affiliation(s)
- C. Jaiseeli
- Department of Electronics and Communication Engineering, School of Electrical and Electronics Engineering, SASTRA Deemed to be University, Tirumalaisamudram, Thanjavur, Tamil Nadu, India
| | - N.R. Raajan
- Department of Electronics and Communication Engineering, School of Electrical and Electronics Engineering, SASTRA Deemed to be University, Tirumalaisamudram, Thanjavur, Tamil Nadu, India
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Essig P, Sauer Y, Wahl S. Contrast Sensitivity Testing in Healthy and Blurred Vision Conditions Using a Novel Optokinetic Nystagmus Live-Detection Method. Transl Vis Sci Technol 2021; 10:12. [PMID: 34614164 PMCID: PMC8496416 DOI: 10.1167/tvst.10.12.12] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose The aim of the current study was to develop and validate an automated contrast sensitivity (CS) test using a live- detection of optokinetic nystagmus (OKN) and an adaptive psychometric procedure. In addition, the study sought to replicate the known effect of defocus on CS for the OKN-based measurements in emmetropic participants. Methods Fifteen participants viewed a horizontally moving grating while their eyes were tracked with an infra-red (IR) eye-tracker. To simulate the clinical conditions of the CS measurements, the participants were stimulated monocularly as the left eye was occluded by an IR filter. The horizontal eye position was continuously analyzed for OKN responses, and the stimulus contrast was changed by an adaptive psychometric method depending on the outcome. Furthermore, the newly proposed OKN live-detection was verified against an offline analysis and an expert-observer judgement. The OKN-based CS was measured for six spatial frequencies at normal vision and three levels of defocus using spherical convex lenses. Results The newly proposed OKN live-detection method showed a sufficient detection performance for implementation of adaptive procedures, and the detection rate is similar or better compared to offline detection methods. Spatial frequency and defocus had a significant effect on the OKN-based CS (P < 0.0001 for both). Conclusions The current study presents a novel method to measure motion CS in an automated way, combining the real-time detection of OKN and an adaptive psychometric procedure. Furthermore, the known effect of defocus on CS was successfully replicated with the newly developed tool. Translational Relevance OKN-based CS is a novel approach to assess spatial vision, which is sensitive to subtle effects of defocus, allowing use with nonverbal patients and infants. Furthermore, the newly developed tool may improve the performance of such measurements.
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Affiliation(s)
- Peter Essig
- Institute for Ophthalmic Research, University of Tübingen, Tübingen, Germany
| | - Yannick Sauer
- Institute for Ophthalmic Research, University of Tübingen, Tübingen, Germany
| | - Siegfried Wahl
- Institute for Ophthalmic Research, University of Tübingen, Tübingen, Germany.,Carl Zeiss Vision International GmbH, Aalen, Germany
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Newman JL, Phillips JS, Cox SJ. 1D Convolutional Neural Networks for Detecting Nystagmus. IEEE J Biomed Health Inform 2021; 25:1814-1823. [PMID: 32956068 DOI: 10.1109/jbhi.2020.3025381] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Vertigo is a type of dizziness characterised by the subjective feeling of movement despite being stationary. One in four individuals in the community experience symptoms of dizziness at any given time, and it can be challenging for clinicians to diagnose the underlying cause. When dizziness is the result of a malfunction in the inner-ear, the eyes flicker and this is called nystagmus. In this article we describe the first use of Deep Neural Network architectures applied to detecting nystagmus. The data used in these experiments was gathered during a clinical investigation of a novel medical device for recording head and eye movements. We describe methods for training networks using very limited amounts of training data, with an average of 11 mins of nystagmus across four subjects, and less than 24 hours of data in total, per subject. Our methods work by replicating and modifying existing samples to generate new data. In a cross-fold validation experiment, we achieve an average F1 score of 0.59 (SD = 0.24) across all four folds, showing that the methods employed are capable of identifying periods of nystagmus with a modest degree of accuracy. Notably, we were also able to identify periods of pathological nystagmus produced by a patient during an acute attack of Ménière's Disease, despite training the network on nystagmus that was induced by different means.
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Reinhardt S, Schmidt J, Leuschel M, Schüle C, Schipper J. VertiGo – a pilot project in nystagmus detection via webcam. CURRENT DIRECTIONS IN BIOMEDICAL ENGINEERING 2020. [DOI: 10.1515/cdbme-2020-0043] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Abstract
Dizziness is one of the most common symptoms in medicine. For differentiation of peripheral or central origin of the vertigo, history and clinical examination with detection of a nystagmus is essential. The aim of this study was to detect horizontal vestibular nystagmus utilizing a webcam. In the feasibility study, caloric induced vestibular nystagmus was recorded with conventional video-nystagmography and webcam. Analysis of recorded data was performed with a developed software which used computer vision techniques. A designed algorithm detected nystagmus existence and their direction. The software was evaluated by an expert-rated video-nystagmography. Webcam-based vestibular nystagmus detection is possible. Currently, a clinical application is not approved. Further software improvements are necessary to increase its accuracy.
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Affiliation(s)
- Sophia Reinhardt
- Department of Otorhinolaryngology , Düsseldorf University Hospital , Düsseldorf , Germany
| | - Joshua Schmidt
- Department of Computer Science , University of Düsseldorf , Düsseldorf , Germany
| | - Michael Leuschel
- Department of Computer Science , University of Düsseldorf , Düsseldorf , Germany
| | - Christiane Schüle
- Department of Otorhinolaryngology , Düsseldorf University Hospital , Düsseldorf , Germany
| | - Jörg Schipper
- Department of Otorhinolaryngology , Düsseldorf University Hospital , Düsseldorf , Germany
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Newman JL, Phillips JS, Cox SJ, FitzGerald J, Bath A. Automatic nystagmus detection and quantification in long-term continuous eye-movement data. Comput Biol Med 2019; 114:103448. [DOI: 10.1016/j.compbiomed.2019.103448] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Revised: 09/13/2019] [Accepted: 09/13/2019] [Indexed: 01/18/2023]
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An investigation into the diagnostic accuracy, reliability, acceptability and safety of a novel device for Continuous Ambulatory Vestibular Assessment (CAVA). Sci Rep 2019; 9:10452. [PMID: 31320726 PMCID: PMC6639326 DOI: 10.1038/s41598-019-46970-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2019] [Accepted: 07/08/2019] [Indexed: 11/08/2022] Open
Abstract
Dizziness is a common condition that is responsible for a significant degree of material morbidity and burden on health services. It is usually episodic and short-lived, so when a patient presents to their clinician, examination is normal. The CAVA (Continuous Ambulatory Vestibular Assessment) device has been developed to provide continuous monitoring of eye-movements, allowing insight into the physiological parameters present during a dizziness attack. This article describes the first clinical investigation into the medical and technical aspects of this new diagnostic system. Seventeen healthy subjects wore the device near continuously for up to thirty days, artificially inducing nystagmus on eight occasions. 405 days' worth of data was captured, comprising around four billion data points. A computer algorithm developed to detect nystagmus demonstrated a sensitivity of 99.1% (95% CI: 95.13% to 99.98%) and a specificity of 98.6% (95% CI: 96.54% to 99.63%). Eighty-two percent of participants wore the device for a minimum of eighty percent of each day. Adverse events were self-limiting and mostly the consequence of skin stripping from the daily replacement of the electrodes. The device was shown to operate effectively as an ambulatory monitor, allowing the reliable detection of artificially induced nystagmus.
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Black JM, Jacobs RJ, Phillips JR, Acosta ML. The changing scope of Optometry in New Zealand: historical perspectives, current practice and research advances. J R Soc N Z 2019. [DOI: 10.1080/03036758.2019.1587476] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Affiliation(s)
- Joanna M. Black
- School of Optometry and Vision Science, The University of Auckland, Auckland, New Zealand
| | - Robert J. Jacobs
- School of Optometry and Vision Science, The University of Auckland, Auckland, New Zealand
| | - John R. Phillips
- School of Optometry and Vision Science, The University of Auckland, Auckland, New Zealand
| | - Monica L. Acosta
- School of Optometry and Vision Science, The University of Auckland, Auckland, New Zealand
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Abass A, Lopes BT, Eliasy A, Wu R, Jones S, Clamp J, Ambrósio R, Elsheikh A. Three-dimensional non-parametric method for limbus detection. PLoS One 2018; 13:e0207710. [PMID: 30475843 PMCID: PMC6261009 DOI: 10.1371/journal.pone.0207710] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Accepted: 11/03/2018] [Indexed: 12/12/2022] Open
Abstract
Purpose To present a novel non-parametric algorithm for detecting the position of the human eye limbus in three dimensions and a new dynamic method for measuring the full 360° visible iris boundary known as white-to-white distance along the eye horizontal line. Methods The study included 88 participants aged 23 to 65 years (37.7±9.7), 47 females and 41 males. Clinical characteristics, height data and the apex coordinates and 1024×1280 pixel digital images of the eyes were taken by an Eye Surface Profiler and processed by custom-built MATLAB codes. A dynamic light intensity frequency based white-to-white detection process and a novel three-dimensional method for limbus detection is presented. Results Evidence of significant differences (p<0.001) between nasal-temporal and superior-inferior white-to-white distances in both right and left eyes were found (nasal-temporal direction; 11.74±0.42 mm in right eyes and 11.82±0.47 mm in left eyes & superior-inferior direction; 11.52±0.45 mm in right eyes and 11.55±0.46 mm in left eyes). Average limbus nasal-temporal diameters were 13.64±0.55 mm for right eyes, and 13.74±0.40 mm for left eyes, however the superior-inferior diameters were 13.65±0.54 mm, 13.75±0.38 mm for right and left eyes, respectively. No significant difference in limbus contours has been observed either between the nasal-temporal direction (p = 0.91) and the superior-inferior direction (p = 0.83) or between the right (p = 0.18) and left eyes (p = 0.16). Evidence of tilt towards the nasal-temporal side in the three-dimensional shape of the limbus was found. The right eyes mean limbus contour tilt around the X-axis was -0.3±1.35° however, their mean limbus contour tilt around the Y-axis was 1.76±0.9°. Likewise, the left eyes mean limbus contour tilt around the X-axis was 0.77±1.25° and the mean limbus contour tilt around the Y-axis was -1.54±0.89°. Conclusions The white-to-white distance in the human eye is significantly larger in the nasal-temporal direction than in the superior-inferior direction. The human limbus diameter was found not to vary significantly in these directions. The 3D measures show that the limbus contour does not lay in one plane and tends to be higher on the nasal-inferior side of the eye.
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Affiliation(s)
- Ahmed Abass
- School of Engineering, University of Liverpool, Liverpool, United Kingdom
| | - Bernardo T Lopes
- School of Engineering, University of Liverpool, Liverpool, United Kingdom.,Federal University of São Paulo, São Paulo, Brazil
| | - Ashkan Eliasy
- School of Engineering, University of Liverpool, Liverpool, United Kingdom
| | - Richard Wu
- Central Taiwan University of Science and Technology, Taichung, Taiwan.,Pacific University, College of Optometry, Forest Grove, Oregon, United States of America
| | - Steve Jones
- School of Engineering, University of Liverpool, Liverpool, United Kingdom
| | - John Clamp
- UltraVision CLPL, Leighton Buzzard, United Kingdom
| | | | - Ahmed Elsheikh
- School of Engineering, University of Liverpool, Liverpool, United Kingdom.,National Institute for Health Research (NIHR) Biomedical Research Centre at Moorfields Eye Hospital NHS foundation Trust and UCL Institute of Ophthalmology, London, United Kingdom
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15
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Abstract
OBJECTIVE The aim of this study was to develop computational methods for estimating limbus position based on the measurements of three-dimensional (3-D) corneoscleral topography and ascertain whether corneoscleral limbus routinely estimated from the frontal image corresponds to that derived from topographical information. METHODS Two new computational methods for estimating the limbus position are proposed: One based on approximating the raw anterior eye height data by series of Zernike polynomials and one that combines the 3-D corneoscleral topography with the frontal grayscale image acquired with the digital camera in-built in the profilometer. The proposed methods are contrasted against a previously described image-only-based procedure and to a technique of manual image annotation. RESULTS The estimates of corneoscleral limbus radius were characterized with a high precision. The group average (mean ± standard deviation) of the maximum difference between estimates derived from all considered methods was 0.27 ± 0.14 mm and reached up to 0.55 mm. The four estimating methods lead to statistically significant differences (nonparametric ANOVA (the Analysis of Variance) test, p 0.05). CONCLUSION Precise topographical limbus demarcation is possible either from the frontal digital images of the eye or from the 3-D topographical information of corneoscleral region. However, the results demonstrated that the corneoscleral limbus estimated from the anterior eye topography does not always correspond to that obtained through image-only based techniques. SIGNIFICANCE The experimental findings have shown that 3-D topography of anterior eye, in the absence of a gold standard, has the potential to become a new computational methodology for estimating the corneoscleral limbus.
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Sangi M, Thompson B, Turuwhenua J. An Optokinetic Nystagmus Detection Method for Use With Young Children. IEEE JOURNAL OF TRANSLATIONAL ENGINEERING IN HEALTH AND MEDICINE 2015; 3:1600110. [PMID: 27170889 PMCID: PMC4848063 DOI: 10.1109/jtehm.2015.2410286] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/04/2014] [Revised: 02/16/2015] [Accepted: 02/24/2015] [Indexed: 11/08/2022]
Abstract
The detection of vision problems in early childhood can prevent neurodevelopmental disorders such as amblyopia. However, accurate clinical assessment of visual function in young children is challenging. optokinetic nystagmus (OKN) is a reflexive sawtooth motion of the eye that occurs in response to drifting stimuli, that may allow for objective measurement of visual function in young children if appropriate child-friendly eye tracking techniques are available. In this paper, we present offline tools to detect the presence and direction of the optokinetic reflex in children using consumer grade video equipment. Our methods are tested on video footage of children ([Formula: see text] children and 20 trials) taken as they freely observed visual stimuli that induced horizontal OKN. Using results from an experienced observer as a baseline, we found the sensitivity and specificity of our OKN detection method to be 89.13% and 98.54%, respectively, across all trials. Our OKN detection results also compared well (85%) with results obtained from a clinically trained assessor. In conclusion, our results suggest that OKN presence and direction can be measured objectively in children using consumer grade equipment, and readily implementable algorithms.
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Affiliation(s)
- Mehrdad Sangi
- Auckland Bioengineering InstituteUniversity of AucklandAuckland1010New Zealand
| | - Benjamin Thompson
- Department of Optometry and Vision ScienceUniversity of AucklandAuckland1010New Zealand
| | - Jason Turuwhenua
- Auckland Bioengineering InstituteUniversity of AucklandAuckland1010New Zealand
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