How Does Dry Eye Affect Vision?

The tear film on the surface of the eye is the first thing light strikes before passing through the cornea, through the lens and on to the retina. If light is obscured in any way prior to reaching the retina, vision becomes blurry or cloudy. This is how cataracts affect vision! The tear film, being the first thing that light hits, is also subject to that same issue. If the tear film starts to scatter light then vision becomes affected. So how does this tear film start to scatter light?

Normally right after blinking a nice thin clear transparent film of tears is formed over the cornea. This tear film lasts until the next blink. If you recall, one cause of dry eye is the tear film evaporating away too quickly. Instead of lasting between blinks, the tear film breaks up after just a few seconds. This causes the cornea to be exposed and causes symptoms of dry eye. When the tear film evaporates too quickly, it becomes irregular. Instead of being nice and clear and smooth and allowing light to pass through with ease, light is scattered by this irregular tear film and vision becomes cloudy and blurry.

A key feature of the vision from dry eye is fluctuation. After every blink, the tear film becomes smooth again (even if just for a second) and vision sharpness up for this brief time before becoming blurry again. Also, patients will notice an increase in fluctuation and blurriness during tasks that dry the eyes out more such as prolonged computer use or reading.

But dry eye doesn't have to affect the way you see. A few simple steps to treating dry eye can have a dramatic influence on vision.

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