MERCURY BAY OPTOMETRIST

Brett can perform a number of tests to determine key indicators for good sports vision such as:

DYNAMIC VISION (DV) 

is the ability to see the object of regard moving when the player is stationary, e.g., a golf ball in flight, or when the object is still and the athlete is in motion, e.g., when hurdling, or when both the player and the object are in motion, eg, a running shot in tennis. Deficits in this ability can affect clarity, depth perception and timing. 

BROCK STRING

This simple piece of apparatus can train SL. It consists of a long string, usually 10 or 20 feet long, upon which different colour beads are strung. The subject holds one end of the string with his finger at the bridge of his nose while the other end is held by the trainer. The exercise is for the subject to quickly focus the bead of regard when it is moved in and out, as well as focussing quickly from one bead to another. Provided the two eyes are functioning, the string should appear double and converging in a 'V' to meet at the bead of regard in all positions of gaze, e.g., up and out, down and in, etc. Being able to move the string in all directions can pinpoint errors in the visual system that would otherwise escape detection.If the V appears nearer the bead of regard then the eyes tend to over-converge and the subject will tend to hit too soon, putt too short, etc. Conversely, if the V appears beyond the bead then the opposite is likely to occur. Inscribed on the beads are letters which enable the subject to fine tune his focussing.

If the subject has only one eye that functions centrally then only a single string will be seen, but the exercise of quickly focussing the beads when they are rapidly moved can be used, and once again in different directions of gaze, commensurate with the sporting situation.

CENTRAL-PERIPHERAL AWARENESS (CPA) 

is the ability to keep focussed centrally while being aware of essential information around. This is not the same as tunnel vision, where there is no peripheral input. CPA is essential in almost every sport and in some, like boxing and motor racing, can be life-saving. If javelin throwers wear blinkers, they cannot throw properly. They need to be aware of the javelin's tip and tail and of their own place in the arena. Archers are aware of wind conditions peripheral to the target. Tennis players during a rally watch their opponent's racket, hitting arm, etc. but are also aware of the ball they have just hit. Even a 100-metre sprinter benefits from good CPA. An example of poor CPA occurred when Leroy Burrell, at the time the world's fastest 100m runner, had a lane in the Olympic final where, because he has only one functioning eye, he wasn't aware of the seven other runners on his blind side. He didn't win a medal. A different lane might have helped.

Sports-people are sometimes unaware of a failing in a particular area of their periphery. A badminton player, for example, may have a poor high backhand due to seeing the shuttlecock late. Both coach and player may recognise this as a player's weakness but only by the use of a Peripheral Awareness Trainer (PAT) can it be established rationally and objectively. A primary instruction in all sports is to keep one's head as still as possible. To this I would add another: move the eyes minimally. Both rules save energy and are likely to improve performance. Peripheral awareness is processed visually by the magno system.

PERIPHERAL AWARENESS TRAINER (PAT)

The PAT is an excellent instrument for training this facility. It consists of eight three-foot spokes radiating from a central panel. At the end of each spoke is a light-emitting diode (LED). The LED’s light up randomly and the subject fixates a central constant red light. Each time a led lights, the subject is instructed to move a hand-held joystick. At the end of each complete cycle, the times taken to detect the peripheral lights in each direction are displayed.It is useful to observe the subject's stance as well as any eye and head movement throughout the testing as this helps when analysing the resulting data, collected after three cycles. For familiarisation, the distance from PAT to subject may be six feet at first, but to obtain a better assessment of CPA, closer distances are used. The subject soon discovers that, for faster reactions, both head and eye movements have to be kept to a minimum.There is a practice effect and fatigue factor with all the equipment, and different layers of difficulty can be introduced when a plateau of achievement has been reached. This will be discussed later.Since peripheral vision is reduced when running, it is useful to train on the PAT while running on the spot, to avoid too much visual field constriction.

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PURSUIT EYE MOVEMENTS 

Pursuit eye movements are smooth tracking movements, one of two types of eye tracking abilities. An illustration of this activity is following a tennis lob; another is an outfielder in a cricket match watching the ball's flight before attempting to catch it. Pursuit movements are important in all ball sports and the throwing events in athletics; in fact, whenever a trajectory has to be followed.

WAYNE SACCADIC FIXATOR (WSF)

This instrument consists of lights set in three concentric circles around a central light. It can be used at various heights and angles to simulate playing conditions. Usually the subject is at arms' length and is told to stand in a balanced position with feet shoulder-width apart, blink normally and keep the head as still as possible. One of the many uses of this instrument is to practise pursuit movements by following a series of lights which appear to move in smooth motions in three modes: circularly, horizontally and vertically, while keeping the head still.

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KING-DEVICK CHARTS

These charts can be used with an overhead projector so that the size of the objects and the distance from them can be varied. Each of three charts consists of numbers, with each chart progressively more difficult to read in a flowing manner because of the increased spacing between the numerals. Each chart is read as quickly and accurately as possible, while both errors and speed are noted to produce scores. This test simulates tracking a ball lost in flight because of floodlights or an obstacle in the line of vision.

SACCADIC EYE MOVEMENTS 

Saccadic eye movements are fast, jerky movements aimed at fixating an object on to the eye's most acute area of seeing, the foves. Table-tennis players, during rallies, are rarely far from the table and the ball is hit with such speed that only saccadic eye movements are quick enough to see the ball. In cricket matches, close fielders have to make saccades when attempting to stop and/or catch the ball. With fatigue, saccades become less accurate. The same training instruments are used as for Pursuit Eye Movements. With the Wayne Saccadic Fixator, a programme of random lights set for any duration can be used to train Saccadic Eye Movements. The subject is instructed to fixate each light as it comes on. The length of time the light stays on can be varied, the shorter the time, the harder the task. During the exercises, the SVT watches the subject's eyes to ensure correct fixation.

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EYE-HAND COORDINATION 

Eye-hand coordination involves the integration of the eyes and the hand(s) as a unit. Any deficit in this ability will show itself in clumsy handling of the ball in sports like rugby and basketball, and poor racket control in sports like tennis and squash.

EYE-HAND SPEED 

Eye-hand speed is the time required to perceive and respond with the hand(s) to a visual stimulus. It is the ability for the eyes and hands to be not only highly coordinated but fast. The best boxers are often said to have 'fast hands', i.e., they can throw a volley of punches in a second. Table-tennis players, too, have very fast hands. A deficit in this parameter makes for slower responses, poor timing, and the sports-person may appear sluggish.

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EYE-FOOT SPEED 

Eye-foot speed is the time required to perceive, and respond by moving the feet, to a visual stimulus. Any sport involving a high degree of mobility needs good eye-foot speed - for instance, fencing, racket games and, of course, football. A deficit in this ability reveals itself when a player does not move quickly enough to reach a ball, moves away from an attack, etc. Motor racing, where a mistake in a fraction of a second can prove fatal, is a sport where both eye-hand and eye-feet speeds must both be of a very high order.

EYE-BODY BALANCE 

Eye-body balance is the ability to shift one's centre of gravity so that the body is always balanced. Along with fitness and concentration, it is common to all elite sports people. It can be seen to particularly good effect in winter sports such as downhill skiing, slalom racing and the luge, as well as in a summer sport like wind-surfing. Failure to have good body balance makes the athlete appear ungainly and awkward - in short, uncomfortable.

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ANTICIPATION SPEED (AS) 

Anticipation speed is the ability to be in the right place in good time. It can be seen in good players in team games like football and volleyball. In skeet shooting, it is the gun which has to be pointing and firing in the right place at the right time. AS is closely allied to speed of recognition, in that if the visual clues are read early enough it allows time to be in the right place. An elite sports-person is often considered as 'finding space' in a team game and being unhurried. Having good timing is a consequence of highly developed AS. Failure to have this ability gives a player poor timing, slowness and wrong-footedness. Commentators often talk of a reflex shot or save, when really it is a learned response. It is a combination of using visual recognition quickly and having good AS.

EYE-BODY SPEED 

Eye-body speed is the speed at which the body as a whole moves in response to a visual stimulus. If highly developed it amounts to being 'quick off the mark'. It is an essential quality in many sports, often seen as a sudden acceleration, eg, in ball games and in some cycling events where the rider suddenly pounces from an almost stationary position.

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AUDITORY FACTORS

Reactions are quicker to sound than to vision. Asking tennis players, for example, to wear earplugs when practising heightens their visual awareness. All the computerised equipment that is used in SVT (sports vision training) has volume controls. If there is no aural feedback, a bleep, then there is a tendency for the subject to glance at the display score panel, which leads to a drop in scoring ability. Switching off the volume controls is another way of increasing the level of difficulty.

CONCENTRATION AND NOISE:

In this context 'noise' means a distraction, a disturbance of concentration. Paradoxically, it is a way of learning to improve concentration while doing any of the exercises. The noise can take a number of forms:

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• questioning the subject

• playing music not to his/her liking

• literally, making a noise.

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If the subject can maintain the same level of ability with 'noise', then it imbues him/her with confidence in the knowledge that any adverse circumstances in the sport proper can be overcome, eg, sudden changes in wind direction, crowd disturbances or provocative opponents. Exercising in this way involves two tasks creating divided attention.

CONCLUSION

Often you read about a player's wonderful 'vision' or having a marvellous 'eye'. These are players who have a highly tuned visual system. They are the ones who see clearly, quickly, read only essential cues, and have the motor responses to act quickly and accurately. In fact, these are the very qualities that SVT tries to instil. The transfer from improvement in the laboratory/consulting room to the sporting arena has not been proved; all the benefits achieved have been largely anecdotal. The multi-factorial nature of sports performance make its study complex, so that the effect of SVT is not clear. The area needs well-constructed and well-controlled studies to prove (or disprove) a positive relationship between SVT and performance. Sports Vision Training cannot change recreational players into great ones, but it can help to improve their sporting performance, as well as giving an edge to elite performer.