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Achromatopsia
Published in Alexander R. Toftness, Incredible Consequences of Brain Injury, 2023
Other disorders of color include color anomia, which is an inability to remember the names of colors (Zeki, 1990). When you perceive extra color instead of experiencing the absence of color, such as during a migraine (see Migraine Headaches), that is called chromatopsia (Azimova et al., 2016). It is also possible to have cerebral achromatopsia and not realize it (see Anosognosia). That is, you can become colorblind without realizing that you have become colorblind (von Arx et al., 2010). If you'll forgive the pun, I would say that conditions of color perception are quite colorful, and if you take one thing away from this chapter—to share at parties, of course—it's that color perception works a bit differently for everyone.
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.
Are we there yet? The developing state of mobile access equity
Published in Assistive Technology, 2022
In evaluating the accessibility features for vision disabilities, the study evaluated individual features that improve access for people with vision disabilities. Eighty-nine percent (89%) of phones had the ability to adjust font; 87% voice input; 84% screen magnifier; 80% biometric log-in; 79% accessibility menu; 76% built-in TTS; 74% digital assistant; 64% contrast adjustment; 61% color contrast; 57% full access screen reader; 50% color inversion; 35% dark theme; 32% grayscale; 30% braille access; 23% FM radio; 17% physical # keypad; 15% procure TTS; 9% physical QWERTY. These data suggest a general trend toward improved accessibility for people with vision disabilities, particularly regarding input, output, and display customization features. Braille access and biometric log-in had the most significant percentage point increase from 2017 to 2019. Five of the features are assistive to people with color perception difficulties.
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
A novel KCNV2 mutation in a patient taking hydroxychloroquine associated with cone dystrophy with supernormal rod response
Published in Ophthalmic Genetics, 2021
Pei-Kang Liu, Joseph Ryu, Lung-Kun Yeh, Kuan-Jen Chen, Stephen H. Tsang, Laura Liu, Nan-Kai Wang
CDSRR typically presents with moderate-to-severe central vision reduction, photophobia, nyctalopia, and abnormal color perception in the first two decades of life (3–5). It is estimated to account for 2–4% of all cone or cone-rod dystrophy cases (14,15). Given the variability and subtlety of structural appearance, the diagnostic application of fundus imaging is limited (4,5). In contrast, ffERGs according to international Society for Clinical Electrophysiology of Vision (ISCEV) standards are invaluable in differentiating CDSRR from other cone or cone-rod dystrophies. The characteristic ffERG changes of CDSRR comprise distinctive rod-system findings of a conspicuous implicit time delay and reduced amplitude of dim flash (rod-specific response) and a disproportionately increased (so-called supernormal) response to a higher intensity stimulus (combined rod and cone response). The light-adapted single-flash cone response and 30-Hz flickers are considerably reduced and delayed, indicating universal cone dysfunction (7,8,16–18). Banin et al. recommended that genetic analysis of KCNV2 mutations should be considered in all patients of apparent implicit time delay in the scotopic response with abnormal cone response, even if the ffERG does not show supernormal rod response (7).