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Cyanopsia after cataract removalEdit

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 an artificial intraocular lens; these artificial lenses are clear, 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.

Cyanopsia from sildenafilEdit

The author of Viagra and vision (n.d.) attributes cyanopsia after taking sildenafil to diminished enzyme activity sensitising the retinal rod cells. Rod cells are most sensitive to light of wavelengths near 498 nm; such light appears blue-green. When light levels are low enough for both rods and cone cells to be active (mesopic vision) the enhanced rod activity induces the bluish visual tint.


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