Night blindness 101

The term night blindness sounds alarming, as though some people are actually blind at night.  There is a small percentage of the population that does in fact experience true night blindness, but it is rare and often the result of late stage eye disease.  In optometry, it is not common to use the term night blindness although we do encounter a significant number of patients who complain of poor night vision.  The symptoms are usually blur and dimming of vision at night, glare and haloes around lights and poor adaptation from light to dark environments.  How do you know if what you are experiencing is normal or a result of something more serious?

There are a handful of eye conditions that can create symptoms of poor night vision.

Photo Courtesy of kenleewrites on Flickr

Photo Courtesy of kenleewrites on Flickr

  1.  Patients who have had surgery to the corneas such as LASIK or corneal transplants may notice glare and haloes around light.  They may also experience diminished contrast sensitivity which can cause images in the evening to appear more dim.  Unfortunately, surgical results usually cannot be reversed.
  2. Cataracts are the number one cause of decreased night vision.  Patients over the age of 40 will begin developing mild cataracts.  This is when the natural lens inside the eye becomes more yellow and opaque as a result of age and ultraviolet exposure.  Cataracts can cause haloes and dimming of vision in the dark and decreased contrast sensitivity.  Fortunately, cataracts are easily removed thereby restoring problems with night vision.
  3. Corneal diseases such as keratoconus and severe dry eyes may also affect one’s vision in the evenings causing double vision or haloes.  For some of these patients, specialty contact lenses or eyedrops will alleviate these symptoms.
  4. Newer technology has also allowed optometrists to detect higher order aberrations in some patients.  For these patients, standard spectacle lenses may not improve night vision problems.  An instrument to detect higher order aberrations will determine whether a patient requires a specialty custom-made spectacle lens to improve night vision.

Some patients do in fact have true night blindness caused by an eye disease in its late stage.  Usually, symptoms begin slowly over time and progress to an inability to see in the dark.  These patients usually suffer from one of two eye conditions.

  1.  Retinitis pigmentosa is an inherited eye disease of the retina, the tissue that lines the back wall of the eye and captures visual images.  Retinitis pigmentosa affects the rods of the retina and causes slow deterioration of these structures.  The rods (unlike the cones) are responsible for night vision and for peripheral vision.  As the disease progresses, patients will notice a decrease in their ability to see in the dark and in the periphery.  Unfortunately, there is no current cure for retinitis pigmentosa.
  2. Glaucoma is an eye disease where the optic nerve slowly degenerates.  Patients with glaucoma usually have no symptoms in the early stages of the disease.  As the disease progresses, nerve fibers in the retina begin to deteriorate resulting in a decrease in peripheral vision as well as night vision.  Usually, patients do not experience symptoms of poor night vision and poor peripheral vision until the late stages of the disease.

Now that you know the causes, what are some ways to alleviate or improve poor night vision?  The simplest solution is to wear an updated pair of prescription glasses (if you have a prescription) with higher index lenses and an anti-glare coat.  Your optometrist can also inform you if you require customized lenses to correct for higher-order aberrations.  If your night vision problems are not a result of surgery or any eye diseases that you are aware of, then it is important that you visit your optometrist for a comprehensive eye examination.

– Cindy P. Wang, O.D., F.A.A.O.
California Optometric Association
www.coavision.org

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Summer is coming – protect your eyes while having fun in the sun!

Summer is coming

Most of us understand that we need to protect our skin from UV rays to avoid sunburn and potential sun damage and skin cancer.  But, we often overlook the need to protect our eyes from these harmful UV rays as well.  UV damage can increase your risk of cataract, macular degeneration, pterygium (benign growths on the white part of the eye) and also damage the sensitive skin around the eyes.  The following four tips from the American Optometric Association will help you keep you and your family’s eyes healthy all summer and all year long in the sun.

Here’s what you need to know to protect your eyes:

  1. Wear protective eyewear any time your eyes are exposed to UV light, even on cloudy days and during winter months. Glare from snow on the ground can reflect UV into your eyes.
  2. Sunglasses should block out 99-100% of UVA and UVB radiation and screen out 75-90% of visible light.  Polarized lenses is a good way to do this because they can specifically block out the most prominent light rays while maintaining clear vision.
  3. Grey colored lenses are best. They reduce light sensitivity without altering the color of object and provide the most natural color vision without distortion
  4. Don’t forget your kids! They need sunglasses too as they tend to spend more time outdoors than adults do.

One last tip: Don’t forget about a good quality sunglasses  frame. It should be big enough to protect your eyes and the skin around your eyes from the sun.

Use these tips to keep your eyes safe and healthy through all your outdoor activities.  As always, continue to get routine eye health and vision examinations yearly.

Enjoy the summer!

~Lisa M. Weiss, OD, MEd, FAAO

How to clean your eye glasses

So, you’ve been working in the yard and your eye glasses are covered in grit or your kid decided to take his mud pies a little too seriously. That means it may be time to break out the good ol’ soap and water. Here are some quick steps to follow to make sure you are cleaning your glasses without needlessly damaging them along the way.

1) Rinse the glasses under warm water.
2) Use mild dish soap and gently rub across lenses with your thumb in a circular motion.
3) To get the dirt around the nose pads you can use a toothbrush, just make sure to not touch the lenses or you could scratch them.
4) Rinse the glasses in warm water.
5) Wipe clean with microfiber cloth.

If they aren’t covered in tons of grit, but the daily use has smudged oils and more onto your lenses you can just use an eye glasses spray cleaner and the micro fiber cloth to do the job.

You are done! Check out this video for information about general eye glasses care.

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