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HomeArticles › Only Players with Fit Eyes Survive

Only Players with Fit Eyes Survive

December 2006
by Dr. Bill Harrison

A player with a significant vision problem rarely progresses very far in the game of baseball. They either do not perform well enough or find the game too frustrating to continue pursuing it. The game simply has a significant concept “survival of the fittest.” If you can’t throw you don’t become a pitcher, if you can’t run you don’t become a centerfielder, if you can’t field you don’t become a shortstop, and if you have an uncorrected vision problem you likely won’t be a very good hitter.

The vision problem may be minor but if results in a slight misjudgment of pitch velocity by 5 mph their bat position will be off by 2 feet. Or if it delays the hitter’s ability to read the pitch by ten feet, the result is a shortening of the amount of time to react dramatically.

For each of the last thirty years I have evaluated the eyesight of hundreds of baseball players during various team’s spring training. At the major league level, the problems revealed usually are very subtle. These are slight vision problems that would not affect the common person on the street, but can have an affect in hitting major league pitching. Most major league players have learned that the smallest eyesight problem can be a handicap to them and get the problem resolved. Most choose to have their vision corrected with the appropriate contact lenses, laser surgery or some times eye training.

Players at any age will perform better and feel more confident when they use high quality equipment. Due to the technological revolution equipment just gets better and better.

The player’s body is also a part of his equipment. For certain, his eyes are the most important pieces of his equipment he has. Imperfect vision that is considered to be adequate for normal living is not adequate for top baseball competition.

Hitting off of all-star caliber pitching will usually reveal the quality of vision that a player possesses. Any hitter that has a high batting average, limited strike outs and hits for power must have adequate vision for the level he is playing. Likewise any hitter that has a low batting average, frequent outs and displays limited power likely has some form of vision problem.

Perhaps the best test of a baseball player’s vision is to compare his results and specifically his timing when playing under lights or poor seeing conditions the way he performs in daylight with good illumination on the ball. Another insight is comparing the hitter’s performance against high speed pitching with average speed pitching.

The notion of 20/20 vision is a poor basis of the quality of a baseball player’s vision. If you you think you have 20/20 eyesight, try reading a sports page article while running in place. Sure, you can do it to some degree, but not very rapidly and not without mistakes.

20/20 simply means that a person can identify the majority of black letters presented on a white background at twenty feet of the specific size of 8.75mm. in height. That height is the correct height because it relates to the eyes ability to identify a letter that has a height that subtends a 1 minute of arc in relationship to a line drawn from the bottom of the letter to the fovea in the back of the eye with a line drawn from the top of the letter to the same spot on the fovea.

One reason 20/20 is a poor basis for comparisons is that it is a designation based on the premise that both eyes are working together. A designation indicating that the right eye sees 20/20 and the left eye sees 20/20 is more informative and relative to a player’s needs. The odds are very high that if the visual acuity designation for the two eyes is not exactly the same, the player will have reduced depth perception.

Another limitation of the 20/20 reference is that the standard visual acuity test uses black letters on a white background. This is called a high contrast test. We know that acuity measurements drop when a person is presented with low contrast visual acuity tests. In reality, baseball takes place with far less contrast than black and white tests. The awareness of seam rotation on a pitched ball is a determination involving low contrast, particularly when the ball gets discolored and the times the sun is not shining directly on a new, white ball.

Some players have difficulty seeing and subsequently hitting game pitching despite being told they had 20/20 eyesight. This is usually because one or both eyes are myopic. Myopia is known as nearsightedness. It is possible to require a prescription to see perfectly but still have 20/20 eyesight without correction. With uncorrected myopia, players are late in their reactions to higher speed pitches. They are very late reacting to pitches, especially when hitting under the lights. Even when they hit the ball hard, they will tend to hit the ball late and often will not fully extend their power into their swings.

This can be the case in a player whose eyes have never been examined by an eye doctor or by a player wearing a correction that needs changing.

A player can also have 20/20 uncorrected eyesight if he is hyperopic, or farsighted. It is possible for the player to have a rather large amount of uncorrected hyperopia and pass every eye test provided by a school nurse or staff of the team physician or trainer. This is not necessarily a problem for a baseball player. However, it is common that players who have uncorrected hyperopia also have the tendency for their eyes to want to turn in. The next effect of that tendency is for everything to look closer than it really is. It will make balls appear faster than they actually are. Players with this tendency cannot wait on pitches. They tend to be very good with high-speed fastballs, but simply can’t wait for any type of off speed pitch. Correction of their vision doesn’t make their eyesight clearer, but can slow the ball down, give them more time and improve their ability to wait on the pitch.

If you see a player who is consistently late on pitches, consider that he might have nearsightedness, astigmatism or a combination of the two. If a player can’t wait on pitches, but is a good fastball hitter, consider that he may have farsightedness. If the player has poor and inconsistent timing, consider that he probably has a depth perception problem. If he tends to consistently swing above or below the ball, consider that he may have astigmatism.
Should a player have an annual eye examination? There are various considerations on answering that question, including how important the player’s baseball career is to him and his family and how important his eyes are to him and his family.
If a player chooses to have an annual eye examination ideally it should be done one to three months prior the competitive season. Until age twenty, eyes can change within six months. A player may have a problem in February even though his eyes tested fine in August. If he does need a vision correction he should have a month to get use to the correction, particularly if it involves toric soft contact lenses.

If the player gets glasses or contact lenses, their value should be assessed against live pitching. In batting practice, they may initially be a distraction, not much value in batting practice, and be rejected. Correction of minor vision problems typically provides benefits when hitting against game speed pitching.
If you are suspicious that one of your players may have a vision problem, look at his mom, dad or other family members. Are they wearing glasses when they watch games? If so, this increases the chance markedly that the player may also have a vision problem since there is a definite heredity component to vision problems. Of course, mom and dad may be wearing contact lenses or have had laser surgery. Therefore, it is best to ask them directly if they or any family members have had a vision problem.

Even though they may be avid fans, most eye doctors don’t know what the visual challenge is like to stand in attempt to hit a high speed fastball, followed by an assortment of curve balls, split finger fastballs, changeups, etc.

An eye doctor is primarily responsible and concerned about ruling out significant visual problems related to high contrast testing and a wide variety of eye diseases. They will typically do a great job for their patients in that regards. In some offices, staff members do the vision related tests. Many offices do not even have tests that evaluate distance depth perception, contrast sensitivity or the quality of eye muscle coordination that relates to tracking a pitch. And many doctors do not see the need for full correction of vision to achieve the best possible visual acuity.

Tell your players upon making an appointment for an eye examination they should ask the appointment secretary if those tests can be made for you. If the appointment secretary does not confirm their availability, another office or doctor should be selected.

Furthermore, the player should tell the doctor in advance that if there is even the slightest of eyesight problems that he would prefer to be fit with soft contact lenses. Due to advances in one day “single-use” soft contact lenses the player will be comfortable and free of distraction even on the first day of wear.
The decision to evaluate soft contact lenses involves an additional step of having the player trained to put the contact lenses on and to remove them and the provision of a few evaluation lenses to wear. Upon trying the lenses out on the baseball field, under the lights, and against live pitching, the decision can be made whether to invest in a season’s supply of lenses.

A vision correction for a player must be safe, free of distractions or distortions and provide the best possible eyesight. After forty years of technological advances, most everyone can wear contact lenses in the 21st century. Unless the player has astigmatism, the safest and easiest way to wear lenses is the use of the single-use contact lenses. These lenses eliminate the potential problems of contamination, reaction to solutions, etc. and are virtually problem free. The correction of astigmatism requires special lenses, known as toric lenses. Toric lenses have improved markedly in the last few years, but they often take a few office visits and two to four weeks to fit perfectly.

If the player chooses to wear glasses, they must have lenses that are made of Polycarbonate or Trivex materials. These materials will not break upon impact. Unfortunately, there is not a frame that meets the ideal needs for the player. The eyewear frames that are safe are usually so thick that they are distractive. The eyewear frames that are thin are not as safe. Contact lenses are clearly a better choice.

LASIK Eye Surgery is an option for players over eighteen years of age. This surgery should be performed at least ninety days prior to the start of the training season. This is because if a re-treatment is necessary, it is not recommended to do so until a minimum of ninety days after the initial treatment has passed. The results of LASIK Eye Surgery can be wonderful, but there is a real risk of problems that has to be taken in to consideration.

Even perfect eyesight in each eye does not assure you that your player has the quality of depth perception needed to accurately see the initial velocity and then the changing velocity of a pitch. This is important because, if a hitter misjudges the velocity of a pitch by 5 mph, their bat position will be off by 2 feet.

Everyone has some degree of one-eyed depth perception, but two-eyed depth perception is a unique skill. Most importantly, it is a key skill required to accurately time the speed of high velocity objects, i.e. the ball, moving directly at a person.

So, just what is depth perception? It is the ability for the brain to use, to put together, the slight differences in information that reaches the two eyes. That difference is created because each eye is looking at all objects from a slightly different angle due to their physical separation on a face. Seeing objects clearly has little to do with depth perception, because you can see clearly with just one eye. However, you require the information from both eyes in order to perceive depth. A one-eyed hitter can see the seams rotating and can see the trajectory of a pitch. But, a one-eyed hitter cannot see, read, or measure the velocity of the ball accurately.

One-eyed depth perception is all one needs to see adequately from the dugout that pitches have different speeds. But two-eyed depth perception is required to see slight changes of speed from the batter’s box. By the way, seeing change of speed of pitches is tough enough from the catcher and umpire’s viewpoints, but it is very difficult from the position that the hitter views the ball.
Obviously, most everyone has two eyes and should be able to have two-eyed vision. However, our research has confirmed that most people do not see straight ahead with both eyes simultaneously. The brain tends to pay attention to one eye or the other. If the brain cannot match up the different slightly different information from the two eyes, the brain will be forced to make a choice. It will reject all or part of the information from one eye. The brain can suppress or turn off visual information it cannot use. In this case, their depth perception deteriorates markedly.

I developed a training product specifically for baseball players called the 3-D Depth Perception and Tracking Trainer. It has a distinct advantage in that it does not require the player to lose valuable time on the practice field or take time out of each day to go to an office for the training. The player can do the training at any time they choose. It has both hand-held and computer-generated targets that are easy to use. Training with the 3-D Depth Perception and Tracking Trainer will help overcome the problem that most players have… that is relying on the central vision of just one eye which invariably reduces depth perception and timing.

Although a normal eye examination may indicate that a player has clear eyesight, good depth perception and no apparent problem with suppression, these are static tests in the eye doctor’s office. A baseball player requires dynamic vision. Judging the quality of a player’s vision must take into consideration what occurs with rapid movement, fatigue, stress and/or a loss of concentration. I believe that most players face the challenge of reduced dynamic depth perception unless they have a perfect situation—limited or no movement, fatigue or stress. My belief is that the better they develop their dynamic depth perception, the less likely they will experience a loss of the use of this skill in these potentially trying situations.

I recommend that a coach’s best consideration is to make certain that their players train their depth perception to its highest possible level. Utilizing specific equipment, training depth perception requires a daily concentrated 20-minute minimum of total focus. It usually develops to a high level within a 21-day period. These six hours will payoff with better ability to see slight changes of speed of the same pitch, and, therefore, the hitter will acquire better timing. The improvement in timing usually results in greater confidence and concentration. Improved timing, confidence and concentration are valuable assets for the hitter to carry to the plate.

In summary, having a player’s vision tested is wise. Encouraging that each player train his depth perception and the eye muscles involved in tracking the ball is even wiser.

About the Author
Dr. Bill Harrison has been working with professional athletes for over 30 years and can be reached at or 866-627-5400. Performance Fundamentals, Inc. makes available unique baseball training products including the 3D Depth Perception and Tracking Trainer that can be found at as well as an interactive online vision training site at