Red eyes, blurry vision and stuff like that

Questions and perspectives about eyes and vision.

Posts Tagged ‘filmy vision

Blurry vision with dry eyes

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You might initially think that having dry eyes wouldn’t make that much difference to your vision, but it can.

People can get dry eyes for a number of reasons, but most of the time, it’s not lack of tears (quantity) that’s the problem, but rather instability (quality) of the tear film that creates the dry eye symptoms.

The eyes have a thin film of tears on them all the time, and to keep clear vision, that film needs to be stable.  After a blink, when the tear film gets reset, the tear film will remain stable for a number of seconds.  Hopefully this period is long enough to preserve a smooth front surface to the eye until your next blink occurs.  If you hold your eyes open long enough, you’ll feel the sting, and perhaps the blur, that comes as that tear layer loses its structure, and dry patches develop on the front of the eye.  The sting comes because the nerves in the cornea are very sensitive, and let you know as soon as the tear film has broken down.  The blur comes because the front surface of the eye, a very important part of the optics of the eye,  is no longer as smooth.

A rough front surface to the eye means that light falling on it will not be focussed regularly, but instead, light will get scattered in different directions.  This may be

  • seen as blur if you’re looking at fine detail,
  • seen as a flare or a halo around a bright object especially at night,
  • seen as a vague haziness/ filminess or loss of contrast as you look at things,
  • felt as the symptom we call glare.
  • accompanied by the dry, gritty, ‘something in your eye’ feeling.
  • seen as blurred vision that needs a few blinks to clear it.

Usually, having a blink will restore the regularity of the tear film, but if the eyes have been getting dry for a while, then even the ‘reset’ tear film won’t be as stable, and the symptoms will remain no matter how much you blink.

Therapy for dry eye can be targetted towards:

  • adjusting the environment to reduce tear instability
  • adding drops to increase the volume of tears, or the stability of tears
  • working on co-existing conditions of the eyes and lids that are contributing to poor tear film quality.

Dry eye vision symptoms seem to be more common amongst people working at computer screens and contact lens wearers.

There are of course, many other things that can cause blurry vision, but dry eye is definitely one of them.