Cyanopsia

From Wikipedia, the free encyclopedia

Cyanopsia is a medical term for seeing everything tinted with blue. It is also referred to as blue vision. Cyanopsia often occurs for a few days, weeks, or months after removal of a cataract from the eye. Cyanopsia also sometimes occurs as a side-effect of taking sildenafil such as Viagra, Cialis, and Levitra (Viagra and vision, n.d.).

Cyanopsia is a medical symptom and not a sign. It is a purely subjective state, and can be caused by a physical or functional abnormality of the eye, a physical or functional abnormality of the brain, or by nothing at all (i.e., it can be purely psychological). Cyanopsia, if unaccompanied by any other sign or symptom, is not an indication of any disease or disorder. Unless it causes an impairment or significant distress, it is not in and of itself diagnostically relevant.

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[edit] Cyanopsia after cataract removal

The eye's lens is normally tinted yellow. This reduces the intensity of blue light reaching the retina. When the lens is removed because of cataract, it is usually replaced by a clear intraocular lens allowing more intense blue light than usual to fall on the retina, leading to the phenomenon.

Hayashi and Hayashi (2006) compared visual function in people given yellow-tinted intraocular lenses with that in people given non-tinted intraocular lenses. Those with the yellow-tinted lenses were less likely to report cyanopsia than those with the clear lenses. Hayashi and Hayashi found no differences in visual acuity or in contrast sensitivity between the two groups.They also found that no one reported cyanopsia three months after the cataract operation, suggesting that some form of neural adaptation or colour constancy had taken place.

[edit] Cyanopsia from sildenafil

The author of Viagra and vision. (n.d.) attributes cyanposia after taking sildenafil from the drug's lowering the activity of an enzyme in rod cells of the retina that leads to these cells being more sensitive to light. Rods are sensitive to wavelengths of light from 400 to 600 nanometers, with peak sensitivty at 498 nanometers (see Trichromatic color vision). Lights of wavelengths around 498 nm appear blue green. When the overall light level is low enough to allow both rods and cone cells to be active, mesopic vision, the rod contribution to colour vision provides the blue tint experienced by some users of sildenafil.

[edit] References

Hayashi, K., & Hayashi, H. (2006). Visual function in patients with yellow tinted intraocular lenses compared with vision in patients with non-tinted intraocular lenses. British Journal of Ophthalmology, 90, 1019-1023.

Viagra and vision. (n.d.). Author. Retrieved January 31, 2008, from http://www.visionweb.com/content/consumers/dev_consumerarticles.jsp?RID=85.

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