What Causes Red Eyes in Photos?

Why Eyes Look Red in Photos, and What You Can Do

Whether they show up in a cherished moment or in a random snap during a night on the town, red eyes can ruin otherwise frame-worthy photographs. In this article, we’ll explore the red eye phenomenon and how to prevent (and correct) red eyes in photos so you can capture life’s greatest moments, just as they are.

What Causes Red Eyes?

Although it could signal a serious eye condition such as cataract or retinal detachment, the most common reason for the “red-eye effect” is much more benign. The appearance of red eyes in photos occurs when the camera flash (or some other bright light source) is reflected from the retina.

Here’s how it works: Light hits the eye and causes the pupil to widen, allowing light to be detected by cells at the back of the eye (the retina) which then convert the light rays into electronic pulses that create visual images in our brain.

The problem, at least for photographers, is that not all of the light is absorbed; some is reflected back to the camera lens. When the light is reflected, it illuminates the rich blood supply of the connective tissue at the back of the eye and produces the red color you see in pictures.

How to Prevent Red Eyes in Photos

The reason some of your photos are ruined by red eyes is that our pupils can’t constrict fast enough to prevent the light from reflecting off the blood vessels. While there isn’t anything you can do to make your pupils constrict any faster, there are a few simple measures you can take to help prevent the dreaded red-eye effect.

  1. Don’t look directly at the camera lens. If you have time to direct your subjects before taking their picture, ask them to look slightly away from the lens. This will prevent their eyes from catching the flash at a direct angle, which can reduce the likelihood of light reflection being captured in the photo.
  2. Improve the lighting in the room. In darker rooms, the pupils of the eye are already widened to bring in enough light to see. In these instances, the flash from the camera can result in redness, as the pupil is unable to constrict before the photo is captured. You can make a small correction by allowing more light in the room or moving to a brighter area.
  3. Use the anti-red-eye function. Most modern cameras (and a growing number of smartphones) have a red-eye reduction feature to help users capture frame-worthy photographs every time. This feature emits a quick succession of light before the camera takes the picture. As a result, the subject’s pupils constrict before the photo is taken and thereby reduce the likelihood of the red-eye effect.
  4. Move the flash and lens further apart. This method doesn’t work for smartphones or internal-flash cameras, but if you’re using a camera with an external flash you can move the flash unit away from the camera body to minimize the red eye problem. This red eye fix prevents light reflecting from your subject’s pupil from entering the lens.

Why Do Some People Get Red Eyes, and Others Don’t?

There are some individuals who don’t ever seem to be cursed by the red eye affliction. It could be that they stand at just the right angle or that their head is tilted to avoid the reflection. Maybe they’re tall and stand at the back during group photos, further away from the flash. Or, it could be that their eyes have a thicker epithelium that soaks up the light from the flash.

While this condition can also reduce the likelihood of red eyes in photos, the likelier culprits are the angle of the subject’s head blocking the reflection, or that they’ve positioned themselves further back from the camera.

Do Red Eyes in Pictures Mean Anything Else?

The red-eye effect in photos is an aesthetic problem that can be corrected with simple adjustments, apps or software tools. However, it is important to know that there may be underlying health-related vision problems causing the issue. For example, if only one eye is consistently red in photos, it could mean the subject has misaligned eyes, or strabismus. A white or yellowish glow in one eye could be even more serious, signaling an eye condition such as cataract, retinal detachment, or infections inside the eye. In children, this white or yellowish shine could also be a warning sign of a rare but serious childhood cancer called retinoblastoma.

If you notice anything else unusual about your eyes or your family’s eyes in photos, speak with an eye doctor to rule out more serious vision problems.

Barnet Dulaney Perkins can help you manage your eye health and can provide surgical care when advanced eye treatments are needed. Contact us today to keep your eyes healthy

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