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Cricket has been the subject of many scientific studies (www.sports-vision-institute.com). Judging the speed, line and the length of the ball while batting is challenging. Pre-release and release search strategies of the bowler's action enable the batsman to predict ball trajectory, speed and spin. Ball tracking requires a complex visual task, such as smooth ocular movements with slower bowlers, to jump vergences and corrective saccades when the speed of the ball is too fast to track.
Elite skills
Numerous studies have found accurate eye movements differentiate elite players from club players. All players track the ball as it is ?rst delivered. Only the highly skilled performer can use a rapid anticipatory saccade to the bounce point, followed by a brief period of tracking before the ball is struck. In many sports that require open skills of an interceptive timing nature, we see that when the ?ight of the object is predictable, pursuit tracking is directed early to the object and over the ?rst part of ?ight. Whenever the movement of objects is unpredictable - bounce, spin or seam - then the gaze adapts to deal with late changes in object ?ight. It is the elite performer who is better at adapting the gaze so that the rapidly changing conditions can be perceived in time to effectively adjust the shot.
Other visual skills brought to play, such as depth perception, are thought to be binocular. The speed of the ball questions the validity of the role of true stereopsis when batting against fast bowlers. If we draw a parallel with baseball, Babe Ruth, an all-time great batter, was amblyopic.
So perhaps a more important visual component is ocular dominance.
In keeping with many sports that are played 'side on', a disproportionate number of players are 'cross dominant'. This term is given to players that bat left handed while being right eye dominant or bat right handed while being left eye dominant. In each of these cases the 'side on' style of batting allows the dominant eye to be closer to the bowler and without obstruction from the nose while playing the shot. In many cases players are normally dominant in other activities or sports, namely right handed and right eye dominant, but adopt the cross dominance only when batting.
I suggest to coaches of youth players that this dominance should be considered when choosing to bat right or left handed.
The patient focus of this article is England wicketkeeper Matt Prior who is left eye dominant and bats right handed. Prior first presented to me wearing contact lenses to correct a low level of myopia, -2.00DS. The problems he reported included dry eye, difficulty seeing under floodlights and visual instability.
Refitting him with daily aspheric contact lenses improved his floodlight vision by correcting the spherical aberrations. This was more important in view of his larger than average pupils. These lenses also improved some of the dry eye issues due to the change in lens modulus and inherent lubricating agent. Wicketkeepers are more likely to suffer from dry eye because of reduced blinking when repetitively preparing to catch every ball while fielding up to six hours a day.
Laser treatment
The England wicketkeeper before Prior was Paul Nixon. He had opted for Lasik surgery at Accuvision as he found contact lenses unsatisfactory for his oblique and irregular astigmatism. This surgery has significantly improved his visual performance, taking him from 6/9 to 6/4.5. This coincided with a dramatic improvement in batting and an eventual England call-up the year following the surgery.
Paul Nixon recommended Prior consider laser treatment. As optometrist to the England & Wales Cricket Board it is my duty to provide players with a balanced view on the benefits and risks of each form of vision correction. This includes the comparative risks with contact lenses and laser eye surgery.
With this in mind Prior was provided with a list of a number of laser clinics and informed of the risks and the benefits of different forms of surgery. Previous investigations with contact lenses had demonstrated that correcting spherical aberration had a significant benefit. Subsequently Wavefront measurement and treatment was conducted at Accuvision.
Prior underwent surgery in October 2007 and has reported 'better vision than ever' - no fluctuation with the blink and no dry eye. The previous dry eye condition had been induced by lens wear and blink patterns.
Lasik has an association with dry eye, in such cases of poor blink (VDU use), but I have found patients often find less dryness after surgery than they suffered with their contact lenses. Notwithstanding this, all patients should be advised of the possibility of dry eye symptoms following Lasik, albeit transient in most cases.
To date Accuvision has corrected three England wicketkeepers: Matt Prior, Paul Nixon and Chris Read. In a sport that collates a wide range of performance statistics it is easy to analyse performance before and after Lasik of these players. The results are quite an eye opener (Table 1).
Note that each player has performed better the year following surgery, most notably Paul Nixon and Chris Read who had been astigmatic contact lens wearers. While it impossible to associate the improvement directly to the treatment there seems to be a trend.
Increasingly, athletes like all patients are considering laser eye surgery as method of refractive correction. Our duty is to help patients to make an informed decision about the most appropriate modality of refractive correction.
The previous article in this series (19.03.10) highlighted England rugby player Lewis Moody, who wears contact lenses. So what are the issues with laser surgery in contact sports such as rugby? If Lewis was interested in undertaking surgery, clinics can offer surface-based treatments that do not have the same risk of flap displacement that exists with Lasik. However, the visual rehabilitation is slower and a significant window of time is required before players can recommence training or playing. The postoperative use of steroids will need to be signed off by the relevant doctor and the sports federation.
As a final comment I would like to say that as clinicians we have a duty of care to athletes, as to all our patients, to enable them to reach their goals. ?
Acknowledgement
I wish to thank all those athletes that have entrusted their vision to me and allowed these articles to go to print.
? Nick Dash is an optometrist with a special interest in sports vision. He has no commercial interests in any of the companies highlighted