Quantitative Analysis of Illusory Movement: Spatial Filtering and Line Localization in the Human Visual System

Jansonius, Nomdo M.; Stam, Lucas; Jong, T. de; Pijpker, B.A.

doi:10.1068/p7716

Cited by 4 publications

(11 citation statements)

References 30 publications

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“…However, with a decrease in SNR the filter width in the direction of the Ascan may increase intentionally (to improve the information yield, that is, sacrificing the high spatial frequencies in order to get a more accurate estimate of the low spatial frequencies in situations with poor SNR) [18,19] or unintentionally (for example, due to errors in the registration of adjacent A-scans or layer thickness inhomogeneities). Generally, as long as layer thickness >> filter width the effect is negligible whereas the effect becomes important as soon as layer thickness and filter width are of the same order of magnitude [9]. This implies an increase in illusory-movement artifacts with a decrease in layer thickness.…”

Section: Discussionmentioning

confidence: 99%

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Influence of coherence length, signal-to-noise ratio, log transform, and low-pass filtering on layer thickness assessment with OCT in the retina

Jansonius¹,

Cervantes²,

Reddikumar³

et al. 2016

Biomed. Opt. Express

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Optical coherence tomography (OCT) images of the retina are inevitably affected by the finite width of the coherence function and noise. To make low-reflective layers visible, the raw OCT signal is log transformed; to reduce the effect of noise the images can be low-pass filtered. We determined the effects of these operations on layer thickness assessment, as a function of signal-to-noise ratio (SNR), by performing measurements in a phantom eye and modeling. The log transform appeared to be the key factor in a SNR-dependent overestimation of peak widths and a less predictive bias in the widths of low-reflective layers.

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Section: Discussionmentioning

confidence: 99%

“…2, right panel). In psychophysics, this phenomenon is known as illusory movement [9,10]. Importantly, illusory movement requires a low contrast between peak and flanking areas, and a large contrast between the two flanking areas.…”

Section: Introductionmentioning

confidence: 99%

Influence of coherence length, signal-to-noise ratio, log transform, and low-pass filtering on layer thickness assessment with OCT in the retina

Jansonius¹,

Cervantes²,

Reddikumar³

et al. 2016

Biomed. Opt. Express

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“…The modulation used in the illusory movement experiment could theoretically trigger the contrast gain control mechanism as this mechanism already starts below our modulation frequency of 2.5 Hz; the applied modulation depth of 0.08, however, is much lower than used in psychophysical experiments targeting contrast gain control [ 23 , 24 ]. Moreover, as the illusory movement was assessed by nulling it with a real movement, contrast gain control should not influence it [ 7 ]. Contrast gain control and contrast adaptation have been shown to be affected in glaucoma [ 25 – 27 ].…”

Section: Discussionmentioning

confidence: 99%

“…A GDx VFI above 35 or any reproducibly abnormal test location at p <0.01 on the FDT test result implied exclusion. If both eyes were eligible, the dominant eye was chosen according to the Dolman method [ 7 ].…”

Section: Methodsmentioning

confidence: 99%

“…The first experiment is based on a psychophysical phenomenon called illusory movement. Illusory movement has been described in detail by Jansonius et al [ 7 ]. In short, a narrow bar or line (width around 1 arcminute) between two fields of which the luminances are sinusoidally and in counterphase modulated in time ( Fig 1A ) appears to make an oscillatory movement.…”

Section: Methodsmentioning

confidence: 99%

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Lateral Inhibition in the Human Visual System in Patients with Glaucoma and Healthy Subjects: A Case-Control Study

et al. 2016

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In glaucoma, the density of retinal ganglion cells is reduced. It is largely unknown how this influences retinal information processing. An increase in spatial summation and a decrease in contrast gain control and contrast adaptation have been reported. A decrease in lateral inhibition might also arise. This could result in a larger than expected response to some stimuli, which could mask ganglion cell loss on functional testing (structure-function discrepancy). The aim of this study was to compare lateral inhibition between glaucoma patients and healthy subjects; we used a case-control design. Cases (n = 18) were selected to have advanced visual field loss in combination with a normal visual acuity. Controls (n = 50) were not allowed to have symptoms or signs of any eye disease. Lateral inhibition was measured psychophysically on a computer screen, with (1) a modified illusory movement experiment and (2) a contrast sensitivity (CS) test. Illusory movement was quantified by nulling it with a real movement; measure of lateral inhibition was the amount of illusory movement. CS was measured at 1 and 4 cycles per degree (cpd); measure of lateral inhibition was the difference between log CS at 4 and 1 cpd. Both measures were compared between cases and controls; analyses were adjusted for age and gender. There was no difference between cases and controls for these two measures of lateral inhibition (p = 0.58 for illusory movement; p = 0.20 for CS). The movement threshold was higher in cases than in controls (p = 0.008) and log CS was lower, at both 1 (-0.20; p = 0.008) and 4 (-0.28; p = 0.001) cpd. Our results indicate that spatially antagonistic mechanisms are not specifically affected in glaucoma, at least not in the intact center of a severely damaged visual field. This suggests that the structure-function discrepancy in glaucoma is not related to a decrease in lateral inhibition.

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Retinal Vessel Caliber Measurement Bias in Fundus Images in the Presence of the Central Light Reflex

Pappelis

Jansonius

2023

Trans. Vis. Sci. Tech.

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Purpose To investigate the agreement between a fundus camera and a scanning laser ophthalmoscope in retinal vessel caliber measurements and to identify whether the presence of the central light reflex (CLR) explains potential discrepancies. Methods For this cross-sectional study, we obtained fundus camera and scanning laser ophthalmoscope images from 85 eyes of 85 healthy individuals (aged 50–65 years) with different blood pressure status. We measured the central retinal artery equivalent (CRAE) and central retinal artery vein equivalent (CRVE) with the Knudtson–Parr–Hubbard algorithm and assessed the CLR using a semiautomatic grading method. We used Bland–Altman plots, 95% limits of agreement, and the two-way mixed effects intraclass correlation coefficient for consistency [ICC(3,1)] to describe interdevice agreement. We used multivariable regression to identify factors associated with differences in between-device measurements. Results The between-device difference in CRAE (9.5 µm; 95% confidence interval, 8.0–11.1 µm) was larger than the between-device difference in CRVE (2.9 µm; 95% confidence interval, 1.3–4.5 µm), with the fundus camera yielding higher measurements (both P < 0.001). The 95% fundus camera–scanning laser ophthalmoscope limits of agreement were –4.8 to 23.9 µm for CRAE and –12.0 to 17.8 µm for CRVE. The corresponding ICCs(3,1) were 0.89 (95% confidence interval, 0.83–0.92) and 0.91 (95% confidence interval, 0.86–0.94). The between-device CRAE difference was positively associated with the presence of a CLR ( P = 0.002). Conclusions Fundus cameras and scanning laser ophthalmoscopes yield correlated but not interchangeable caliber measurements. The CLR induces bias in arteriolar caliber in fundus camera images, compared with scanning laser ophthalmoscope images. Translational Relevance Refined measurements could yield better estimates of the association between retinal vessel caliber and ophthalmic or systemic disease.

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Quantitative Analysis of Illusory Movement: Spatial Filtering and Line Localization in the Human Visual System

Cited by 4 publications

References 30 publications

Influence of coherence length, signal-to-noise ratio, log transform, and low-pass filtering on layer thickness assessment with OCT in the retina

Influence of coherence length, signal-to-noise ratio, log transform, and low-pass filtering on layer thickness assessment with OCT in the retina

Lateral Inhibition in the Human Visual System in Patients with Glaucoma and Healthy Subjects: A Case-Control Study

Retinal Vessel Caliber Measurement Bias in Fundus Images in the Presence of the Central Light Reflex

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