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Ophthalmic Physiol Opt 2021 Apr 9. Epub 2021 Apr 9.

Centre for Applied Vision Research, School of Health Sciences, City, University of London, London, UK.

Purpose: Clinical assessment of rod and cone photoreceptor sensitivity often involves the use of extended dark adaptation times to minimise cone involvement or the use of bright adapting backgrounds to saturate rods. In this study we examine a new rod/cone sensitivity test, which requires minimal dark adaptation. The aim was to establish whether rod/cone sensitivity losses could be measured reliably in patients with retinal diseases that selectively affect rods or cones when compared to age-matched subjects with normal vision. Read More

Doc Ophthalmol 2021 Jan 28. Epub 2021 Jan 28.

Department of Ophthalmology, University Hospital Erlangen, Schwabachanlage 6, 91054, Erlangen, Germany.

Purpose: To study the spatial retinal distribution of electroretinographic (ERG) responses that reflect signals in the L-/M-cone-opponent and luminance post-receptoral pathways.

Methods: ERG recordings to heterochromatic stimuli (sinusoidal counter-phase modulation of red and green LED light sources) were performed, while varying fractions of red and green modulation. Two temporal frequencies of the stimuli were employed: 12 Hz to record ERGs that reflect L-/M-cone-opponent signal and 36 Hz for recording ERG signals sensitive to stimulus luminance. Read More

IEEE Trans Image Process 2021 4;30:657-669. Epub 2020 Dec 4.

The ubiquitous presence of surveillance cameras severely compromises the security of private information (e.g. passwords) entered via a conventional keyboard interface in public places. Read More

Atten Percept Psychophys 2020 Nov;82(8):3993-4006

Department of Psychology, Suzhou University of Science and Technology, Suzhou, China.

Using a radial frequency discrimination task that has not been tested in many previous studies, we examined the dependence of the pattern radius (4 to 16 deg) on the radial frequency thresholds of two different types of concentric radial frequency (RF) patterns: constant circular contour frequency (CCF) RF patterns with different radii, which have the constant physical length of modulation cycle in external real-world space, and constant radial frequency magnified RF patterns with different radii, which have the constant cortical length of modulation cycles. These two types RF patterns used as the reference stimuli had an equal maximum orientation difference from circularity regardless of change in radius. The discrimination threshold expressed by the frequency ratio between RF patterns of different frequencies vs. Read More

PLoS One 2020 8;15(7):e0232784. Epub 2020 Jul 8.

Centre for Applied Vision Research, School of Health Sciences, City, University of London, London, England, United Kingdom.

Purpose: Rod and cone photoreceptor-specific tests can be time-consuming. A new non-invasive test is described. The test is based on the measurement of flicker modulation thresholds with rod- and cone-enhanced visual stimuli, which requires only minimum adaptation time. Read More