A Primer on Providing Sports Vision
A Primer on Providing Sports Vision
Providing this much-needed service to athletes will boost their game — and your practice.
By Steven A. Hitzeman, OD
Dr. Hitzeman is clinical associate professor and has been on the faculty of the Indiana University School of Optometry for more than 30 years. He is presently director of Clinics, director of the Extern Rotation Program, director of Residencies and director of the Sports Vision Program at the School of Optometry.
Most sports vision practitioners know the term "the eyes lead the body," but in today's fast moving sports environment the visual needs of athletes sometimes aren't addressed. Over the last 13 years I've been fortunate enough to develop and co-chair the Amateur Athletic Union Junior Olympic sports vision evaluations for the AOA Sports Vision Section. Over that time we've evaluated thousands of athletes and measured their visual skills. It's surprising to note that each year we discover countless athletes who don't understand vision's role in athletics.
Any practitioner can develop a sports vision specialty in his office. Doing so will not only help the performance of your athletes, but it can also serve as a practice builder, bringing in a new population of patients.
A Needed Service
Most athletes understand that sight or clarity of the image on the retina is important. Very few athletes understand that they must also address the motor components of vision such as pursuits and saccadic eye movements, accommodation, vergence and fusion. Even fewer are aware that vision information processing or the quick interpretation of visual information is also a key visual skill that leads to peak performance.
Athletes of all ages have special visual needs that a sports vision practitioner can evaluate and enhance. We gathered the following remarkable statistics from evaluating our AAU Junior Olympic population:
- Never had an eye examination: 30.1 percent.
- Less than 20/20 in either eye: 31.9 percent.
- Reporting visual symptoms: 34.5 percent.
- Reduced depth perception: 32 percent.
- Inaccurate eye movements: 12 percent.
These figures highlight the need for vision care services in our athletic population. It's interesting to note that 30.1 percent of Junior Olympic athletes have never had an eye examination and 31.9 percent had reduced vision in one or both eyes.
During our discussions with these athletes, we emphasize that their eyes are holding them back if they repeatedly make the same mistake, they make more errors toward a game's conclusion than at its beginning, or if they experience loss of concentration during sports. Late game errors are often no more than a breakdown in the endurance of visual skills that are key to peak performance.
Figure 1. Sample visual profile for a football player.
Development of the Sports Vision Specialist
Sports vision is the art and science of providing vision care for the athletic population. This includes visual skills testing, visual correction including contact lenses, vision enhancement and the prevention and management of eye injuries. The ultimate goal is to ensure that deficits within the visual system aren't interfering with optimum athletic performance.
All eyecare practitioners provide sports vision services in their practices. The weekend athlete and the children we see in our offices who are members of sports teams are our sports vision patients. Only when we assess and enhance sports specific visual skills do we separate ourselves from sports vision practitioners and become sports vision specialists. We can then use this knowledge to consult with athletes, coaches, trainers and teams regarding the visual factors and strategies related to consistent peak athletic performance.
The key to sports vision specialty is understanding basic visual skills analysis and enhancement. This includes identifying visual skills that are important for a particular sport and then evaluating and enhancing those specific visual skills. Improving the athlete's performance comes from enhancement training of specific visual abilities that are considered essential for competitive consistency in a specific sport.
Developing a Sports Vision Evaluation
Sports vision evaluations consist of a variety of testing procedures, some of which are much different from the normal examination testing battery. You need to develop a visual profile when working with athletes or sports teams. First, determine the essential visual skills and the beneficial visual skills for the sport you're testing. Then establish a testing battery that includes the visual skills important for that sport. This battery will become your visual profile, and you can then compare this profile with teammates and other athletes in the same sport. Figure 1 is a sample visual profile for football.
All sports vision evaluations are unique and are determined by location, population and time considerations. It's relatively easy to determine the visual skills to test when an athlete comes to your office simply by determining the athletes' visual demands. Conversely, if you're performing a visual evaluation on a volleyball team and you have one hour to evaluate 15 players at their training facility, you now have a much more difficult task. The tests are limited by time and the number of athletes to be tested.
When you perform any evaluation, have goals in mind. These include making sure athletes know that this testing doesn't substitute for a complete examination. Use a set of protocols so that you can compare all the athletes as to skill level and sport. The primary goal is to determine 100 percent of the visual problems with no over or under referrals.
I believe the following visual skills and corresponding tests will provide the sports vision specialist the most information in the most efficient time frame.
Visual acuity represents the initial testing procedure in a sports vision evaluation. Visual acuity is more important in some athletes because of the visual task involved in their position or sport.
Dynamic visual acuity is visual acuity of a moving target, or with the athlete moving, or with both moving at the same time. When prescribing for reduced visual acuity consider the visual demand for that sport, the level of correction or astigmatism and level of anisometropia. Choices for correction include contact lenses, corneal reshaping, refractive surgery and protective eyewear.
Contrast sensitivity measurements were recently included in the sports vision testing battery. This is the ability to discriminate targets under varying lighting conditions or contrast levels. Contrast sensitivity has increased in importance because contact lenses can degrade contrast sensitivity function if they're dirty or deposited.
Color vision testing is recommended for younger athletes who may not have undergone this testing previously. Color vision can be important in large youth leagues where the uniform colors are so close in shade that color deficient athletes may not be able to distinguish their own teammates.
Oculomotor testing begins with the cover test at distance and at near. The next step is to evaluate eye muscle control and how quickly and accurately the athlete moves his eyes. This includes the visual skills of fixation stability, convergence, divergence, saccades and pursuits. I've used the Visagraph (Compevo AB) for eye movement testing for the last several years. Not only does this instrument measure the quality, speed and accuracy, of eye movement, but the computer program can display a graph of the eye movements for comparison with other athletes. This instrument is the gold standard for eye movement measurement (Figure 2). I use both the number of fixation losses and the speed and quality of saccades in my visual profile. Fixation and centering, or the ability to stay on target, may be the most important visual skill for most sports.
Once you take these measurements it's easy to evaluate which athletes have better eye muscle movements. You can put those with a reduced score on a regimen of vision enhancement to increase the quality of visual skill.
The "Quiet Eye" is a term used by Dr. Joan Vickers to describe fixation on a target. She reports the Quiet Eye occurs in golf when your gaze becomes absolutely still on the ball, just before and as the stroke is performed. Expert putters had a Quiet Eye duration of two to three seconds, while less skilled players held their gaze steady for only one to two seconds. Good putters maintain fixation on the same location on the back of the ball through the backswing, forward swing and for almost one-half second after the ball is struck. I use the theory of the Quiet Eye when I evaluate athletes using the Visagraph.
One of the most important findings in my evaluation is fixation stability. Fixation stability is often the first area to be compromised during stressful conditions, and along with centering on the target it's the key to concentration, particularly late in the sporting activity. Concentration is an essential skill in all athletic activities.
Most athletes perform the correct function, they just do it at the wrong time or in the wrong place because their eyes are giving them misinformation. Because of lack of fixation, the eyes obtain misinformation, which leads to poor performance. Once identified by testing, you can enhance this skill by using the Brock string, computer visual therapy programs and other vision enhancement techniques. Drag racers, golfers and volleyball athletes with whom I've worked showed significant improvement in performance with training in fixation and centering.
Eye teaming and spatial localization are important visual skills for athletes to possess to judge the position of an object in space as well as where they are in relation to other players and the playing field. It's also important to remember the summation effects on acuity when the two eyes are solidly fused. We test this in practice with the Randot Stereo Test. Because this test is performed at near the majority of the time and I prefer to test at distance, I use the Howard Dolman apparatus at a distance of 20 feet. The Howard Dolman apparatus measures stereo-acuity utilizing the relative distance of two pegs in free space. The task is to determine which peg is closer to the subject. Poor performance on this test generally means a lack of eye teaming or reduced distance acuity.
Figure 2. Visagraph for eye movement testing.
This test is far superior to Randot testing in evaluating this skill for an athlete's visual skill profile. If you use the distance Randot, measure the amount of time it takes to complete the test. This can be an alternate way to differentiate the level of depth perception in your population.
Figure 3. A patient wearing a MaxSight amber lens.
Accommodative function is important in many sports activities. Athletes exhibiting this skill achieve vision clarity at all distances as well as the ability to shift focus quickly and accurately. This skill is very important in race car driving and many ball sports in which the ball travels toward and away from you. It's typically measured with Hart charts at near and far distances as a timed task.
Speed of recognition or visual reaction time is often not evaluated in screening protocols. Yet this skill plays an important role in many athletic activities. I work with NHRA Drag Racers and this skill is extremely important for them as races may be won or lost in 0.001 of a second.
The visual system is man's greatest time machine, and even superior speed, size and reflexes can't compensate for the inefficient processing of visual information. We measure this skill with the tachistoscope, which flashes numbers anywhere from 1 second to 0.05 of a second. I will typically display six numbers at 0.05 of a second as a test sequence and record the score of three trials.
One way to enhance this visual skill is using a strobe light. Using a strobe light with an athletic activity can improve the eyes' ability to process visual information rapidly. I'll have athletes juggle or play catch with soft balls under strobe light conditions and then gradually reduce the frequency of the strobe.
Eye-hand coordination plays an important role in most sports. The Wayne Saccadic Fixator is a large screen that contains LED lights embedded in a plasma membrane. These lights are displayed randomly and athletes must reach out and touch the lights as soon as they appear. With this test you can compare this skill for all the athletes on the team you're testing.
Eye-hand coordination plays an important role in all ball sports. The eyes tell the muscles how and when to react, and they judge where the ball will be when it's time to react. I've taught many of the athletes I work with how to juggle. This is the best training tool to enhance this skill. After the athlete has learned to juggle, you then add "noise" in the form of movement and balance challenges by having them either balance on one foot or walk heel to toe. I've even introduced yoked prisms as well as a strobe light to increase the level of "noise" to further enhance eye-hand coordination.
Tinted Lenses in Sports
We realize that visual acuity is better in elite athletes than in the general population. In addition to visual acuity, excellent contrast sensitivity is an important component of the visual system of athletes. Recently the use of tinted spectacles or contact lenses has increased in correcting athletes. This technique is beginning to gain recognition as a bona fide method to enhance contrast sensitivity and therefore help athletes better discriminate their environment and more rapidly distinguish moving objects.
Sports enthusiasts have long recognized that tinted lenses can improve their ability to view and detect objects. From skiers, who in flat lighting have used tinted goggles on the slopes to more easily see moguls, to hunters who have used yellow-tinted lenses to improve their contrast sensitivity and shooting ability, tints of different colors have had a role in sports.
Recently, Bausch & Lomb introduced the Nike MaxSight contact lens series. The company describes these tints as light architecture and devoted several years of research to developing these tints. These contact lenses are designed to sculpt the light that the eye receives for maximum contrast and visual performance. Although independently published, peer-reviewed data pertaining to the benefits of these lenses is lacking, they do seem to have a place in sports vision correction.
The MaxSight lenses are available in two colors, amber and grey-green. Each tint has a list of recommended sports, and they have shown some popularity with players since their release almost two years ago. The MaxSight amber lens (Figure 3) is designed for fast-moving ball sports played in variable outdoor light such as soccer, tennis, baseball and softball. We've fit several soccer and field hockey players with these lenses and have found that although there is a high attrition rate (many players initially wear them and eventually stop), a certain number of players find them beneficial and continue to regularly wear them during day games.
The MaxSight grey-green lens is designed for sports played in bright sunlight such as golf, football, running and rugby. I've found that it's successful for golfers who are looking for a competitive advantage. It's also very popular for golfers who don't desire to wear sunglasses. They enjoy the excellent optics and freedom from the fogging and peripheral distortion of prescription sunglasses. Although this lens blocks 95 percent of UVA and 98 percent of UVB for the cornea, the rest of the eye and adnexa will not be protected from UV exposure. This lens is not intended to replace sunglasses.
Contact Lenses in Sports
Fitting athletes with contact lenses is preferable to fitting them with spectacles because of the visual advantages that contact lenses offer. The reasons for this are many and include sharper image (especially in high prescriptions), increased peripheral vision and elimination of the disadvantages of spectacle movement and fogging.
Although contact lenses provide better visual performance, athletes in sports that pose a high risk for ocular injury must also have prescription protective eyewear. You should adhere to the ANSI z-87.1 standards for lenses and ASTM f803-88a standards for frames when prescribing for athletes.
Over the years I've heard countless athletes tell me that their eye doctor told them that they couldn't wear contact lenses. Most of these athletes had moderate astigmatism or high prescriptions. However, today there are very few athletes who are unable to wear contact lenses. You can fit almost anyone with contact lenses even if it's simply for an athletic event. The many lenses and variety of water contents and materials, especially the silicone hydrogels, have made contact lens fitting for almost all athletes possible.
In dealing with specialized fits such as athletes who have high astigmatism, certain fitting techniques are important. Positional stability of the lens in astigmatic corrections is important for sports that require athletes to move their eyes rapidly and in all positions of gaze. The rotation of toric lenses may negatively affect performance, so larger-diameter soft lenses that rotate less are usually more successful.
Of note recently is the increasing use of the SynergEyes (SynergEyes, Inc.) hybrid contact lens that combines the excellent visual acuity of a rigid lens center with a soft skirt that provides the comfort and stability of a soft contact lens. SynergEyes is free from toric lens rotation, a common problem associated with soft toric lenses that causes inconsistent vision. Athletes who have moderate-to-high astigmatism are beginning to benefit from a lens that doesn't cause the visual fluctuations from lens rotation of a soft toric or the possible dislodgment of a GP lens.
The most difficult issue with contact lenses and athletes is compliance. Studies have shown that almost 100 percent of athletes are noncompliant with at least one step in contact lens care. Almost 95 percent either don't disinfect or clean regularly, 94 percent don't keep their cases clean and 53 percent fail to wash their hands when handling lenses.
Perhaps the most important issue is that athletes want to sleep in their lenses. I don't fit any athlete in extended wear contact lenses. The risk of problems is too high and an athlete who wakes up with an eye infection or inflammation won't be able to participate in his sport. For this reason my lens of choice is a daily lens if it's available in the athlete's power and provides adequate acuity.
Corneal refractive therapy is also highly successful and should be considered for teenage athletes provided a safe corneal physiology exists and the patient is mature and compliant. When successful, this technique allows the best overall visual stability.
Eye care offers many opportunities and challenges. Integrating sports vision into your practice is both fun and rewarding. The athletic population has a need for your services, and you'll find great personal and professional satisfaction by helping your athletes reach their athletic potential. CLS
To obtain references for this article, please visit http://www.clspectrum.com/references.asp and click on document #142.
Contact Lens Spectrum, Issue: September 2007