Red

I have 20/20 vision. I don’t see many pictures in which my eyes glow red.

My wife is visually impaired. Her eyes are affected by a condition called retinitis pigmentosa which involves the gradual death of some of the eyes’ photoreceptors. I often have to edit photos of her to remove the red glow from her pupils.

Is it possible that the flash from a camera could serve as an indicator of visual problems?

The red glowing eyes in photographs are caused by a close flash in low-light conditions when the subjects pupils are dilated (to capture enough light to see clearly) and do not have enough time to contract in response to the bright flash, allowing the light to reflect off the blood sources behind the retina.

While I have only a minimal understanding of ocular biology and structure, I consider it a possibility that the more frequent red eye effect I see in pictures of my wife might be due to her visual impairments. If the photoreceptors are dying and not being replaced as a result of her condition, then the retina might be thinner, thus allowing more of the light from the flash to pass through it than my normal retina would allow. Or it could simply be that her pupils are regularly more dilated than mine because her eyes require more light to function properly anyway.

I see the same frequent red eye effect in pictures of my young son, but articles I’ve read seem to indicate that children’s eyes are generally more likely to cause the phenomenon than adults’ eyes, so my idea of using a camera flash as a kind of rudimentary diagnostic aid clearly would not work in all circumstances.