Driving at night – What should I know?

Courtesy of Johnathon, Flickr Creative Commons

Courtesy of Johnathon, Flickr Creative Commons

One of the most common questions patients ask is how to improve their night vision. In fact, many elderly patients have given up night driving all together.

So, what is it about night driving that makes it so hard? Well certainly, our visual abilities are dependent on light. With reduced lighting comes a variety of limiting factors like reduced visual acuity, poor color vision, decreased depth perception, and impaired peripheral vision. All of these factors combine to make accidents 3x more likely at night.

So, how do we reduce our chances of an accident?

1) It is imperative that your vision is corrected to its maximum potential. A complete eye examination will not only check the best prescription for you – it can also detect potential problems that affect night vision like dry eye, cataracts and macular degeneration, all of which occur with greater frequency with age. Additionally, if you are prescribed glasses at your visit, make sure to obtain lenses with an anti-reflective coating. This coating will reduce glare dramatically and has been shown to improve reaction time.

2) Make sure your windows and headlights are perfectly clean. Every time I clean my windows at a gas station I wonder why I didn’t do it earlier. This advice goes for your glasses too. Even a perfect prescription can be worthless if your glasses are dirty or scratched.

3) Finally, it is important to know your limits. If you have real concerns about night driving there is nothing wrong with asking for a ride, catching a cab or public transportation or just ordering in. Until next time, be safe on the road!

 ~Dr. David Ardaya, OD
California Optometric Association
http://eyehelp.org
http://www.coavision.org

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You may have cataracts?

Courtesy of entirelysubjective on Flickr

Courtesy of entirelysubjective on Flickr

Cataracts are common

Not a day goes by in the office when I don’t tell a patient that he or she has a cataract, which is any kind of clouding in the crystalline lens of our eye. Some patients have heard of the term and understand that it’s a common occurrence as one ages. Other patients are terrified of the term and think it’s a disease that will make them blind. But the patients I relate to are the ones who hear the word cataract, and think “I’m old.”

Cataracts can affect your vision

If it helps, most cataracts develop over decades, from young adulthood onward. As early as 40 years old, we can start to notice the effects of this change over time. The crystalline lens in our eye, which is responsible for focusing light onto our retinas, begins to change shape and chemical structure over time. These changes result in more light scatter and dimming of vision. Usually, a patient will begin noticing glare from car headlights, double or ghost images around letters and lights or that night vision is not as clear or bright.

These are often initial symptoms and do not require treatment. As the cataracts continue to develop, patients’ eyeglass prescriptions may begin to change and they will also experience blurry or cloudy vision with worsening of the above symptoms. When they reach this point, which is about half of patients over the age of 65, cataract surgery may be indicated.

Cataract surgery – not as bad as you’d think

Cataract surgery is the most common surgery performed in the world. Nowadays, it can be a 15 minute out-patient procedure. The cataract is removed from the eye and replaced with an artificial lens implant, called an intraocular lens. With many advancements in this field, the lens implant can also have specialty optics which can correct for astigmatism or for both distance and reading.

What many don’t know is that cataract surgery is an optional procedure. A cataract is not malignant and does not always have to be removed. However, a patient’s vision will improve significantly with a successful cataract surgery. They will notice a much brighter and clearer environment. Some patients who have glaucoma or have a crowding of the internal structures of the eye would benefit from having cataract surgery.

Image

Photo courtesy of Community Eye Health on Flickr

Types of cataracts

There are many different forms of cataracts. In fact, I found a cataract in a 9-month old baby when his mom brought him in for a well-visit eye examination. In such a case where the eye is still developing, clouding of the lens can interfere with visual development and needs to be removed. Other congenital form of cataracts may simply be a cloudy spot on the lens which doesn’t interfere with vision. In this case, there is no need for cataract surgery.

Cataracts can also develop from trauma, use of certain medications and diabetes. Depending on the type, a cataract can slowly worsen over years, or change rapidly requiring surgical intervention within months. For patients whose vision is changing rapidly, I often like to follow them every few months to monitor for vision and cataract changes.

People often ask what can be done to prevent cataracts. Unfortunately, genetics plays a factor so if your parents required cataract surgery, you will most likely need one also. If you’re outdoors, wear a good quality pair of sunglasses that block UVA/UVB rays. This goes for kids as well since exposure to ultraviolet radiation is cumulative. If you’re outdoors for long periods of time, throw on a hat for added protection. Smoking has been shown to cause cataracts also, so limit your exposure to cigarette smoke. If you are currently being treated for diabetes or using steroid medications, be sure to see your internist regularly.

Why wait for your vision to blur? See your optometrist every year!

Most importantly, see your optometrist annually for an eye examination. They can check for cataracts but also determine if there are other factors that may be contributing to a reduction in your vision. It’s not just the lens that helps you to see but a whole network of related structures that work as a team to provide you with optimal vision.  If you require a new pair of glasses, always opt for an anti-glare coat on the lenses, which would further reduce disabling glare symptoms.

~Cindy P. Wang, OD, FAAO
http://eyehelp.org
http://www.coavision.org

 

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