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

Vision therapy to improve academic & athletic performance

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Vision therapy (VT) is a high effective type of physical and perceptual therapy that works on improving eye muscle control and coordination, eye-hand and eye-body coordination, as well as visual processing/understanding and visual cognitive skills.

Seeing takes place in the brain instead of the eyes. The eyes are the instruments which transmit visual images to the brain. The brain then processes and integrates visual information with other systems such as the vestibular system to affect balance and spatial localization, as well as affecting understanding of what is seen or read. VT uses neuroplasticity to improve visual functioning and the activities that require vision.

When most people think of good vision, they think of seeing clearly– that is, having 20/20 vision. While seeing clearly is important, it is only one aspect of vision.

Having good vision involves much more than seeing 20/20. Being a good reader, a good driver, or a good athlete requires mastering a complex set of vision skills, such as eye tracking, eye teaming, visual perception and visual memory. Unfortunately, many children and adults have problems with these types of visual skills. Although they may see 20/20, they do not have good vision. They may have trouble reading or working on a computer. They may have difficulty driving or excelling in sports.

It is estimated that as many as 20 percent of people may suffer from these types of problems. Please click here to see if you may have a treatable vision problem that is interfering with your work, reading or sports performance.

Vision therapy can treat many problems including:

  • Strabismus
  • Amblyopia
  • Visually-related learning problems
  • Visual Impairment after Brain Injury (such as stroke, craniotomy)
  • Double vision
  • Sports Vision – to enhance athletic performance through faster and more accurate visual motor skills
  • Computer Vision Syndrome (headaches, eyestrain, decreased productivity)

Here are the most frequently asked questions about VT:

1. How do I know that I may need VT?

A: There are many symptoms that indicate a need for VT. Some of the more common symptoms are: eyestrain associated with reading or computer use, not performing to potential at school or work, poor eye-hand coordination with sports or handwriting, double vision, print that appears to “move” on the page, and losing your place while reading.

Special tests will determine if your specific vision problems can be treated with VT.

If you have two or more of the following symptoms, you can benefit from VT. It takes energy to compensate for a vision problem, which results in discomfort and loss of productivity. Improving your visual skills can improve your academic, athletic and executive performance.

  • My eyes feel tired or uncomfortable while reading
  • Headaches while reading or studying
  • Reading or computer use makes me sleepy
  • I, or my child, is not performing to my potential in school or work
  • I have difficulty remembering what I have read
  • Frequent loss of concentration while reading
  • Words move, jump, or appear to “swim”
  • Double vision
  • I am a slow reader
  • “Pulling” sensation around eyes while reading
  • Words blur, or go in and out of focus
  • I often lose my place, or jump over letters & words
  • I often re-read the same line over and over
  • I do not like to read for pleasure
  • I have a short attention span while reading compared to other activities
  • I have poor eye-hand coordination while playing sports
  • I have poor depth perception
  • I learn better visually than verbally
  •  I get dizzy reading in the car
  • I have difficulty judging distances such as parallel parking or stopping a car
  • I have difficulty making visual judgments such as the depth of stairs, pouring coffee into a cup

2. What is involved with vision therapy?

A: A vision therapy program incorporates many different exercises that train deficient visual skills. Learning visual skills is like learning to play the piano, or a new sport. VT exercises are performed in our office under the supervision of a vision therapist. We also prescribe home therapy to reinforce and accelerate the development of newly learned skills.

The length of the VT program depends on the nature and severity of your vision problem.

3. What results can I expect?

A: You can expect your vision to improve significantly or completely if you stick to the program as prescribed by the doctor. The amount of your improvement depends on the type of vision problem(s) you have, how well you follow doctor’s orders and how regularly you practice your vision exercises.

4. Will my insurance cover vision therapy?

A: Few insurance plans cover VT, but it depends on your particular insurance coverage. The California Optometric Association has several doctors who specialize in vision therapy who would be happy to help you determine if you have any allowance for vision therapy.

5. What kind of vision problems can be treated with vision therapy?

VT can treat a variety of vision problems including:

  • Strabismus (eye turn)
  • Amblyopia (lazy eye)
  • Oculomotor dysfunction
  • Focusing problems
  • Double vision
  • Convergence insufficiency or excess

Visually-related learning problems

Visual motor or visual perceptual problems can interfere with the input and processing of visual information. This decreases a student’s performance on reading and writing tasks, which are highly dependent on visual skills (see symptom checklist below).

Visual motor problems can occur in these skills: tracking, eye teaming, or focusing.

Visual perceptual delays can occur in: visual-motor integration, visual memory or sequential memory, visual discrimination, visual figure ground, visual form constancy, or speed of visual processing.

Sports performance enhancement therapy

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Photo courtesy of DeusXFlorida on Flickr.com

VT can be used to improve athletic performance through increasing visual accuracy, speed of visual reaction time, depth perception, tracking speed (to follow a target quickly), increasing the span of recognition, and improving eye-hand and eye-body coordination.

Enhancing Executive Performance

VT can be used to improve work productivity by increasing visual stamina, decreasing symptoms such as eyestrain or headaches associated with desk or computer work, improving speed of scanning and reading.

Visual Rehabilitation after Brain Injury

80 percent of the brain is related to visual function; therefore, after an injury to the brain (such as stroke, craniotomy, aneurysm or trauma) visual skills and activities dependent on visual skills (such as walking and driving) are often impaired. VT can be used to train the non-damaged part of the brain to do what the damaged part used to do.

Symptoms of brain injury-related visual impairment include double vision, poor judgment of distance while driving or reaching for objects, hemianopsia or loss of side vision, frequent loss of place while reading, skipping words, sensitivity to light, vertigo, fluctuating vision, bumping into objects, decreased depth perception, leaning to one side, and eyestrain.

Please refer to the section on Brain Injuries for more information.

6. Can Adults benefit from VT?

A: Vision therapy benefits adults. In fact, Dr. Brisco went through VT as an adult, and it has tremendously contributed to her improved reading speed and comprehension, as well as her tennis game!

Vision problems that were not corrected during childhood often persist through adulthood, thus interfering with efficiency and productivity on visual tasks. The majority of vision problems are treatable at any age, but it is better to catch problems early to maximize your potential during your academic and executive career.

~By Elise Brisco, OD, FCOVD, FAAO