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Xanthopsia is a color vision deficiency in which there is a dominantly yellow bias in vision due to a yellowing of the optical media of the eye. The most common causes are digoxin's inhibitory action on the sodium pump, and the development of cataracts which can cause a yellow filtering effect.
Color vision deficiencies can be classified as inherited or acquired. Inherited: inherited or congenital/genetic color vision deficiencies are most commonly caused by mutations of the genes encoding opsin proteins. However, several other genes can also lead to less common and/or more severe forms of color blindness.
Leber's hereditary optic neuropathy (LHON) is a mitochondrially inherited (transmitted from mother to offspring) degeneration of retinal ganglion cells (RGCs) and their axons that leads to an acute or subacute loss of central vision; it predominantly affects adult males, and onset is more likely in younger adults.
Köllner's Rule is a term used in ophthalmology and optometry that pertains to the progressive nature of color vision loss that is secondary to eye disease. This rule states that outer retinal diseases and media changes result in blue-yellow color defects, while diseases of the inner retina, optic nerve, visual pathway, and visual cortex will result in red-green defects.
Cerebral achromatopsia is a type of color blindness caused by damage to the cerebral cortex of the brain, rather than abnormalities in the cells of the eye's retina.It is often confused with congenital achromatopsia but the underlying physiological deficits of the disorders are completely distinct.
Visual or vision impairment (VI or VIP) is the partial or total inability of visual perception.In the absence of treatment such as corrective eyewear, assistive devices, and medical treatment, visual impairment may cause the individual difficulties with normal daily tasks, including reading and walking. [6]
In many cases, only one eye is affected and the person may not be aware of the loss of color vision until the examiner asks them to cover the healthy eye. People may also engage in "eccentric viewing" using peripheral vision to compensate for central vision loss characteristic in genetic, toxic, or nutritional optic neuropathy.
Vision loss in toxic and nutritional optic neuropathy is bilateral, symmetric, painless, gradual, and progressive. Dyschromatopsia, a change in color vision, is often the first symptom. Some patients notice that certain colors, particularly red, are less bright or vivid; others have a general loss of color perception.