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

It’s just the FACTS: Vision & Learning Go Hand in Hand

August has been recognized as the Vision & Learning month.  It would seem appropriate since many children return to school in August or shortly thereafter.  In addition to getting new clothes and supplies for our kids, this yearly routine should spur us to take our children in for a comprehensive eye and vision examination.

Vision is a highly complex and intricate process.  So, it is not surprising that reading and learning is dependent on not only having excellent 20/20 vision, but also accurate eye movement, eye focusing, eye teaming, and visual motor skills.

It’s just the plain ole fact that there is a direct correlation between vision and learning.

Courtesy of woodleywonderworks on Flickr

Courtesy of woodleywonderworks on Flickr

Did you know that…

  • “25% of students in grades K-6 have visual problems that are serious enough to impede learning.” – American Public Health Association
  • Approximately “80% of children with a learning disability have an  undiagnosed vision problem.”– Vision Council of America
  • “1 in 4 children has an undiagnosed vision problem which can interfere with learning and lead to academic and/or behavioral problems.”  – College of Optometrists in Vision Development
  • Studies show that “children who had visual perceptual and eye movement difficulties did poorly on standardized tests.” – Dr. Lynn Hellerstein, FAAO, FCOVD, Past President of COVD
  • “When vision problems go undetected, children almost invariably have  trouble reading and doing their schoolwork.  They often a display fatigue, fidgeting and frustrations in the classroom – traits that can lead to a misdiagnosis of dyslexia or other learning disabilities.” – American Optometric Association
  • A “child with a vision based learning problem has excellent verbal skills, causing parent and educators to think the child must be lazy, have ADD/ADHD, or is learning disabled.”
    – College of Optometrists in Vision Development

A cursory vision screening is just not enough to detect vision-related learning difficulties.  Early prevention of a child’s vision problem is so important for school readiness, learning and academic success.  So make it an integral part of your child’s back-to-school preparations.  Buy school supplies, outfit your child with new clothes, and most important, take your child to see a doctor of optometry for a thorough eye and vision examination.

~Judy Tong, OD, FAAO

(Special thanks to my colleagues Drs. Carmen Barnhardt, Eric Borsting, Ray Chu, and Rebekah Louie.)

Quick Tips for Sports Vision

To do well in sports, you need to have your eyes working at the top of their game. Here are a few quick tips to help you or your athlete perform better:

  • Make sure you have a proper prescription on, whether it is contact lenses or glasses. Having your vision dialed in correctly is the most important step to get your eyes working their best.
  • Be sure to protect your eyes! Polycarbonate or other protective plastic lenses can keep your eyes protected while you play as well as keeping dust or wind from getting in your eyes while you play the sports you love. This table can help you determine which types of eye protection are best for the sport you play. (http://www.allaboutvision.com/sportsvision/eyewear.htm )

    Photo Courtesy of Morgan Burke on Flickr

    Photo Courtesy of Morgan Burke on Flickr

  • Consider color filters for your field of play. Certain types of filters or tints can increase your contrast sensitivity and thereby increase your reaction times. Allaboutvision.com has an excellent table for different tints to help in different sports (http://www.allaboutvision.com/sportsvision/lens-tints-chart.htm ). Remember, the faster you can recognize that curve ball, the easier it will be to adjust your swing!

~Ranjeet S. Bajwa, OD

Getting children ready to go back to school

Summer seems to have just started, but the new school year is only a month away. Many of us get ready for this time by making sure our kids have the right clothes, books and school supplies to start the year off right, but we forget to make sure that our kid’s eyes are working well so that learning in school is easy, comfortable, and fun!

The back to school season is a great time to schedule your child’s eye health and vision exam. Optometrists are able to make sure that not only is your child seeing as clear  as possible, but that all of their other visual skills are working properly to handle the demands of the new school year.

"Reading is Fun" Photo Courtesy of John-Morgan on Flickr

“Reading is Fun” Photo Courtesy of John-Morgan on Flickr

The following are some of the important visual skills necessary for learning in the classroom:

  • Visual acuity — The ability to see clearly at any distance. Seeing 20/20 is only one portion of all of the visual skills necessary for classroom success, but sometimes the only area that is assessed by typical “vision screenings.”
  • Eye Tracking — The ability to follow with the eyes a slow moving object such as the teacher moving around the front of the classroom and the ability for the eyes to follow along a line of print while reading without skipping or re-reading
  • Focusing Flexibility- the eyes ability to maintain focus on objects in the distance and at near as well as shift focus quickly from point to point.
  • Eye teaming — The skill needed to aim both eyes together at the same time.  This is a needed skill for lining the eyes up while reading across of page of print and also to have the very high level of depth perception needed for sports.
  • Eye-hand coordination — The skill needed to coordinate the visual system and the motor system when writing, copying, or playing sports.
  • Visual perception — The skill needed to sort, understand and remember information that is coming into the visual system.

Making sure all of these areas are working at the highest level will help ensure that your child has a successful school year.

~By Lisa Weiss, OD, FAAO