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Cranial Neuropathies II, III, IV, and VI
Published in Philip B. Gorelick, Fernando D. Testai, Graeme J. Hankey, Joanna M. Wardlaw, Hankey's Clinical Neurology, 2020
Tanyatuth Padungkiatsagul, Heather E. Moss
Color perception can be affected by retinal, optic nerve, or cortical lesions. Optic neuropathies often cause acquired dyschromatopsia in the affected eye(s). Discordance between severe dyschromatopsia and mildly impaired visual acuity is a unique characteristic of optic neuropathy which can be useful in differentiating optic neuropathy from other causes of visual loss.
Skin Color
Published in Enzo Berardesca, Peter Elsner, Klaus-P. Wilhelm, Howard I. Maibach, Bioengineering of the Skin: Methods and Instrumentation, 2020
The color under which we perceive the skin depends on a number of variables, including pigmentation, blood perfusion, and desquamation. Because color perception is a subjective sensory and neurophysiological process, the evaluation of color is highly observer dependent. This has been a concern not only in dermatology, but especially so in industries such as dye production and application, printing, etc., in which highly consistent colors are necessary. In order to measure color objectively instead of having it judged by subjective observers, color-measuring devices have been developed.
Eyesight standards for beach lifeguards
Published in Mike Tipton, Adam Wooler, The Science of Beach Lifeguarding, 2018
Sunglasses should not introduce secondary hazards by impeding vision or by being constructed from easily broken materials. Small lenses, no matter how good, will allow UV light to reach the eye. Lenses should be optically regular and a focal to maintain visual acuity and comfort. Lens transparency should be as good as prescription lenses and should not be hazy or fluorescing as this will impair vision, reduce contrast and increase disability glare. Coloured lenses can have a dramatic effect on the detection and recognition of colours. The ability to see a colour depends on the sunglass lens transmitting sufficient light in the bandpass of wavelengths emitted by the coloured signal, for the visual threshold to be exceeded. Grey tint (‘neutral density filter’) allows colours to appear more realistic; brown tint distorts colour perception but increases contrast, acuity and depth perception [6–12]. For best colour perception, Prevent Blindness America recommend lenses that are neutral grey, amber or brown. This organization also recommends that people who wear contact lenses that offer UV protection should still wear sunglasses.
Ethambutol-induced optic neuropathy: Functional and structural changes in the retina and optic nerve
Published in Seminars in Ophthalmology, 2022
Sagnik Sen, Sohini Mandal, Mousumi Banerjee, Ranjitha Gk, Abhyuday Saxena, Swati Phuljhele Aalok, Rohit Saxena
Dyschromatopsia is usually the initial symptom and is out of proportion to the deterioration in vision in cases of EON.4 This is classically documented as difficulty in distinguishing red and green color to begin with. Majority of the affected patients notice a generalized loss of color perception, although few of them may notice that certain colors, particularly red, are less bright. Diminished green color perception with a sense of decreased brightness in one eye has also been noted.45 On the contrary, one report by Polak et al. has noted blue-yellow defects to appear earlier than red-green color vision impairment.42,46,47 The blue-yellow defects could only be detected using the Farnsworth-Munsell 100 hue test and desaturated panel of Lanthony.42,48
The Influence of Coronary Heart Disease on Retinal Electrophysiological Examination (Full-field, Pattern and Multifocal Electroretinograms)
Published in Current Eye Research, 2022
Jascha Wendelstein, Barbara Fuchs, Annika Reffken, Matthias Bolz, Carl Erb
Retinal autoregulation is a natural protection against varying perfusion and affects vessel contractions in such a way as to ensure a constant blood flow.18 Coronary artery disease is related to retinal vessel abnormalities, impairment of optic nerve head microcirculation and reduction of choroidal thickness.19–21 Colour perception depends on cones, which are mostly located in the barely vascularized fovea centralis, which in turn is supplied by the underlying choriocapillaris.18 The limited autoregulation of blood flow in the choroid makes it more sensitive than the retinal circulation to arteriosclerotic impacts. In addition to other effects, acquired colour and contrast vision deficiencies can be symptoms of arteriosclerotic vessels. Functional loss of bipolar- and ganglion cells caused by arteriosclerotic retinal vessels can be prevented as long as autoregulation of these vessels is preserved.3 Previous studies in our clinic showed that colour perception deficiencies are observed in patients with vascular diseases.22
Effectiveness of Low Vision Rehabilitation Using Microperimetric Acoustic Biofeedback Training in Patients with Central Scotoma
Published in Current Eye Research, 2021
Esra Sahli, Deniz Altinbay, Pınar Bingol Kiziltunc, Aysun Idil
Patients with macular disease experience a reduction in visual acuity, contrast sensitivity and color perception accompanied by central scotoma in their visual fields. A shift in the oculomotor reference from the fovea to the PRL was demonstrated in these patients. The re-referencing eye movements according to the PRL are called as oculomotor adaption. In neuronal plasticity, the other adaptive response that plays a role in PRL formation, cortical neurons corresponding to the scotoma begin to receive small activity originating from non-altered neurons nearby and the connections strengthen gradually. This system becomes more stable over time.19 The fixation stability while a patient is looking via PRL is correlated with reading ability.20–22 In patients with central scotoma, reading performance is dramatically reduced and one of the most common complaints of these patients is the difficulty to read. A significant correlation was also shown between reading speed and vision-related quality of life.23 For that reason, the primary goal of the visual rehabilitation should be to help patients be able to read again or improve their reading performance.