Robust pupil center detection using a curvature algorithm

Zhu, Danjie; Moore, Steven T.; Raphan, Theodore

doi:10.1016/s0169-2607(98)00105-9

Cited by 101 publications

(44 citation statements)

References 20 publications

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“…Pupil size was determined by both center-of-mass and ellipse-fit methods at a rate of 200 Hz. [20][21][22] Both measures yield identical results, so center-of-mass calculations were used when pupil images were not obstructed by eyelids or lashes, and ellipse-fit calculations were used for obstructed images.…”

Section: Methodsmentioning

confidence: 99%

Pupillary Light Reflexes are Associated with Autonomic Dysfunction in Bolivian Diabetics But Not Chagas Disease Patients

Halperin

Pajuelo

Tornheim

et al. 2016

The American Journal of Tropical Medicine and Hygiene

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Abstract. Autonomic dysfunction is common in Chagas disease and diabetes. Patients with either condition complicated by cardiac autonomic dysfunction face increased mortality, but no clinical predictors of autonomic dysfunction exist. Pupillary light reflexes (PLRs) may identify such patients early, allowing for intensified treatment. To evaluate the significance of PLRs, adults were recruited from the outpatient endocrine, cardiology, and surgical clinics at a Bolivian teaching hospital. After testing for Chagas disease and diabetes, participants completed conventional autonomic testing (CAT) evaluating their cardiovascular responses to Valsalva, deep breathing, and orthostatic changes. PLRs were measured using specially designed goggles, then CAT and PLRs were compared as measures of autonomic dysfunction. This study analyzed 163 adults, including 96 with Chagas disease, 35 patients with diabetes, and 32 controls. PLRs were not significantly different between Chagas disease patients and controls. Patients with diabetes had longer latency to onset of pupil constriction, slower maximum constriction velocities, and smaller orthostatic ratios than nonpatients with diabetes. PLRs correlated poorly with CAT results. A PLR-based clinical risk score demonstrated a 2.27-fold increased likelihood of diabetes complicated by autonomic dysfunction compared with the combination of blood tests, CAT, and PLRs (sensitivity 87.9%, specificity 61.3%). PLRs represent a promising tool for evaluating subclinical neuropathy in patients with diabetes without symptomatic autonomic dysfunction. Pupillometry does not have a role in the evaluation of Chagas disease patients.

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Section: Methodsmentioning

confidence: 99%

Pupillary Light Reflexes are Associated with Autonomic Dysfunction in Bolivian Diabetics But Not Chagas Disease Patients

Halperin

Pajuelo

Tornheim

et al. 2016

The American Journal of Tropical Medicine and Hygiene

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“…Measurements of the pupil diameter have been performed by a two steps procedure: first, the points laying on the pupil boundary have been detected by using a curvature algorithm [10]; these points have been then interpolated according to the method of Chauduri and Kundu [11], based on an optimum weighted least square circular fitting.…”

Section: B Estimation Of Pupil Diametermentioning

confidence: 99%

Baroreceptor-sensitive fluctuations of heart rate and pupil diameter

Giovannelli

Censi

Bartolini

et al.

2001 Conference Proceedings of the 23rd Annual International Conference of the IEEE Engineering in Medicine and Biology Society

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-It is generally known that the pupil is under the control of the autonomic nervous system. Recently, those rhythms characterizing the autonomic fluctuations of heart period and arterial blood pressure have been detected in spontaneous Pupil Diameter (PD) fluctuations. The physiological mechanisms underlying such variability have not been widely investigated. Aim of this study was to investigate the origin of the pupil fluctuations in humans, using a non-invasive modulation of carotid baroreceptors by Neck Suction (NS). To this purpose, we simultaneously recorded ECG, respiration activity, NS pressure and PD fluctuations from 10 normal subjects. The equipment for the PD measurement and the NS stimulation was developed in our laboratory. The response of the pupil to the NS was studied at stimulation frequencies of 0.10 and 0.20 Hz, by using parametric spectral and cross-spectral estimation. In all subjects, the NS rhythms were clearly detectable in heart rate variability series in both stimulation frequencies and also in the PD spectra with significant coherences (>0.5). These findings suggest that blood pressure fluctuations propagate to the pupil via carotid baroreceptor afferent pathways. However a central contribution can not be excluded.

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“…The curvature algorithm [10] detect pupil center. The accuracy rate is 40% which is detected pupil boundary in an error of less 0.1 degrees.…”

Section: Literature Reviewmentioning

confidence: 99%

Measurement of Unique Pupillary Distance using Modified Circle Algorithm

Saif¹,

Hossain²,

Hasan³

et al. 2018

IJCA

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This research investigated several equations and calculated the pupillary distance using pupils center coordinate. The prior research has provided two conceptual frameworks which may give a unique distance to all human. As Pupillary distance provides a core and unique information as like bio-metric for every human. The researcher did not explore the equation or pattern yet. This research proposed a framework called as Pixellary Pupil Distance and analyze the result. This research use pixel to calculate the pupillary distance where subtracts left pupil pixel with the right pupil and sum up with its distance pixel. Finally, the research sum all the pixel subtraction and its distance what this research called pupillary distance. This research builds and describes a custom dataset for test purpose because the pupil is the core element of eyes and this research did not find any precise dataset of it. The result shows the unicity of pupillary distance. This research also shows the computational time, false alarming rate, noise reduction which is described the performance of the purposed framework.

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Robust pupil center detection using a curvature algorithm

Cited by 101 publications

References 20 publications

Pupillary Light Reflexes are Associated with Autonomic Dysfunction in Bolivian Diabetics But Not Chagas Disease Patients

Pupillary Light Reflexes are Associated with Autonomic Dysfunction in Bolivian Diabetics But Not Chagas Disease Patients

Baroreceptor-sensitive fluctuations of heart rate and pupil diameter

Measurement of Unique Pupillary Distance using Modified Circle Algorithm

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