This month, football has become centre stage as 3.2 billion worldwide tune in to their television to watch 32 teams come together to play 63 matches for the 2014 FIFA Football World Cup in Brazil.1 Football is played by 250 million people in over 200 countries and is the most popular sport in the world.2 In the UK, 1.8 million people play football and it features in the top six most commonly played sports along with cycling, running, golf, tennis and swimming.3
Sport makes up an integral part of our lifestyle and culture. Each week in the UK, 15 million people are involved in some form of sporting activity, be it cycling to work, swimming at a local club, jogging around the park or kicking a football with their friends. Sport England estimates 41 per cent of men and 31 per cent of women are active at least once a week.3
Sport provides countless health and social benefits to individuals and communities and has huge economic value. Being involved in physical sport provides many health benefits and can reduce the risk of diseases such as heart disease, stroke, diabetes, cancer, obesity, mental health problems and musculoskeletal conditions.3 Worth £11bn per annum, sport is one of the top 15 industry sectors in the UK and comes above publishing, advertising and motor services. The sector is estimated to employ more than 400,000.3
The social impact of sports is powerful. For children, sport helps build their confidence, self-esteem and social skills.3 These improvements in self-esteem have been shown to have an impact on crime reduction in youth.3 Children who participate in sport also have improved numeracy. International studies show that sport strengthens social networks and community identity.3
Importance of vision for sport
Sport is clearly important for our patients, however practitioners do not always discuss sports and their specific visual demands during the history taking during eye examinations. Some authorities have suggested that approximately 80 per cent of perceptual input to sport is visual and that a ‘finely tuned’ visual system is ‘critical’ for peak sports performance.4 There is a perceived strong correlation between peak performance and high level visual skills.4 Sports involve a variety of challenging visual aspects including peripheral vision, eye-hand coordination, identifying objects which can be moving or present in low contrast situations, judging speeds and distances, depth perception and quick reactions to moving objects. Both elite athletes and those involved in amateur sporting activities can benefit greatly from having their vision assessed and the options for sports eye care and eyewear discussed.
Introduction to sports vision
Sports vision is defined as the study of all of the visual abilities required in competitive and recreational sports and the development of visual strategies to improve performance, consistency, accuracy and stamina of the visual systems used.5 In general practice we aim to give our patients optimal visual acuity with many achieving better than 6/6. Visual acuity however is not a full and accurate assessment of the entire visual system with many more factors that contribute to overall visual quality and performance needing to be considered. A sports vision evaluation is made up of a full routine eye examination with several specialised tests added specific to the patient and the activities that they are involved in.6 These tests may include eye dominance, eye tracking, eye-hand coordination, depth perception, peripheral awareness, Vernier acuity, colour preference, light sensitivity, contrast sensitivity and visual reaction time.6 Some examples of the specialist vision tests and instrumentation used in a spor
ts vision assessment are outlined below.
Bassin Anticipation Timer
This instrument tests visual coincidence anticipation – the ability to predict the arrival of a moving object at a destination – and is related to eye-hand coordination and anticipation. The test is made up of a runway of light emitting diodes (LEDs) which are illuminated sequentially to simulate an object moving at 1 to 500 mph. The athlete watches the lights and pushes a button when they reach the target (Figure 1). The velocity of the lights can be adjusted to match the relevant sport. Anticipation skills are independent of visual acuity but are influenced by the direction of motion. The superior anticipation skills of racquet sport players are likely to be related to dynamic visual acuity and experience.7
Sports vision trainer
The sports vision trainer (SVT) is a computer-controlled board with 32 or 80 round touch-sensitive lights that can be programmed to simulate the visual demands of a specific sport and a range of different body movements.7,8 As shown in Figure 2, the athlete reacts to lights as they are lit up. This device has three different modes – proactive, reactive and reactive random. Results can be saved and compared with future performance. The SVT assesses eye-hand co-ordination, peripheral awareness reaction time, eye-foot co-ordination, anticipation and reaction time. SVT scores appear to improve with repeat exercises.
[CaptionComponent="407"]Dynamic fixation test
The dynamic fixation test (DFT) effectively measures the speed of the extra-ocular muscles by a combination of vergence and motility using a 1 metre distance and a near chart (Figure 3). The subject holds the near card so that the numbers on the distance card are seen through the hole in the middle of the near card without moving the head or card. This is designed to occur at about 20cm. The subject is asked to read the numbers out, alternating between the near chart and the distance chart. The time taken for three circuits is recorded.9 DFT is thought to be useful for athletes who are playing sports with a moving ball. Over time DFT scores can improve.
[CaptionComponent="408"]Contact lenses in sports
As well as employing dedicated tests, there are other important steps that any practitioner can take to help athletes or sports enthusiasts improve their game and performance. Fitting contact lenses is a clear example of this. Sportsmen and women report that contact lenses can provide clear, comfortable vision during activities and contribute significantly towards their performance.10 As seen in Table 1, contact lenses provide many benefits for people participating in sports.
As contact lenses do not fog up, collect rain drops or dust, vision remains clear in many different environments. Contact lenses also cannot slip, fall or get caught in hair or clothing and they do not interfere with athletes’ helmets or head gear. Binocular vision may be improved with contact lenses because the lens moves with the eye, so minimising prismatic effects.11 Spectacle magnification is reduced and hence they are a preferable correction for anisometropia than spectacles. Depth perception is also improved for the same reason.11 Children fitted with contact lenses have been shown to have improved confidence and self-perceptions of athleticism in sport.12
Some contact lenses have ultraviolet (UV) blocking properties which help provide ocular protection against harmful radiation and, when worn with wraparound sunglasses and a wide-brimmed hat, provide optimal protection against UV. Rays incident from the periphery are internally reflected by the cornea (Figure 4) and have an intensified effect on the nasal conjunctiva and lens. This is thought to contribute to the development of pterygia and cortical cataract.13 UV-blocking contact lenses provide ocular protection here where non-wraparound sunglasses may not.14
[CaptionComponent="409"]Key considerations when fitting contact lenses for sports
Today, soft lenses are the most popular form of contact lens correction, with RGPs making up less than 5 per cent of the UK contact lens market.15 When fitting sportsmen and women, as with all patients, it is essential to consider all the options and fit the best lens for their specific visual and lifestyle needs.
Vision
The athlete/sports enthusiast requires optimal static and dynamic visual acuity. Vision with contact lenses can be influenced by several factors. Wettability is one such factor,16 and it is important to maintain a stable pre-contact lens tear film between blinks. Lenses with embedded wetting agents may provide a more stable tear film and hence a clearer retinal image.17 Deposition can also affect surface wettability18 and therefore lens replacement schedule is another important consideration. Daily disposable contact lenses are generally preferred for sports people as no single cleaning system completely removes all protein and lipid deposition. Where a daily disposable is not an option, a more frequently replaced reusable lens is advised.
A full and accurate prescription is an essential place to start for both spherical and astigmatic prescriptions. Low levels of astigmatism should be corrected to optimise an athlete’s visual acuity. This is especially important in low contrast situations.19 Assessing the rotational stability of toric lenses in diagonal and extreme positions of gaze is important to ensure that the lens will remain stable and deliver optimal vision in the real world. As athletes will complete many eye and head movements during play, a soft toric design that remains stable throughout wear will help provide clear, stable vision. Accelerated stabilisation design (ASD) lenses have been shown to be more rotationally stable during extreme and diagonal eye movements, head movements and are less affected by gravity than prism ballast lenses.20,21,22 ASD lenses have been shown to provide vision as good as spectacles.23
Recent research found that various soft toric prism ballast and peri-ballast design lenses have up to 1.0? vertical base down prism in the optic zone.24 Vertical prism of 0.5? could lead to binocular disturbances25 and decrease stereopsis which is especially important for athletes involved in ball sports. Almost half of all patients with astigmatism of =0.75DC have monocular astigmatism26 and so may need a toric contact lens in one eye only. Athletes with monocular astigmatism fitted with a toric soft contact lens with vertical prism in the optic zone could create or exacerbate disturbances in binocular vision function.27 Clinical studies have not been done to fully characterise the clinical effects of vertical imbalance in monocular astigmatic contact lens wearers. Practitioners should be aware of this potential effect when selecting soft toric designs.
Comfort
Athletes may compete and train in dry and challenging environments such as dusty hill sides for mountain bike riders and air-conditioned gyms for squash players. Poor comfort is a distraction and may impact upon performance. The latest research suggests that surface properties such as coefficient of friction are important for contact lens comfort.28 Providing a lens with a low coefficient of friction (high lubricity) and a highly wettable surface should aid in patient comfort.28 Modulus and lens edge design are also factors that influence comfort.28 As deposition can affect the surface wettability, a short replacement frequency is recommended.18
Lens fit
The importance of the contact lens fit is sometimes overlooked in soft contact lens fitting. How well a lens fits may influence the patient’s eye health, comfort and/or vision. For instance a lens that has inadequate coverage may cause limbal staining and irritation. A lens that is too tight (or steep) may cause vision to blur after blinking, while the opposite occurs with a loose lens.29 Light scatter or flare can be caused by a lens that is moving too much and may also be linked to the size of the optic zone.19 This is especially important for those playing on a floodlit pitch such as hockey players.
Health
To ensure minimal impact on ocular physiology as with all CL fits, practitioners should consider optimal replacement frequency, lens fit, oxygen delivery for the modality, effective care regimes or daily disposable and surface properties such as coefficient of friction and surface deposition for the individual patient needs.
For those participating frequently in sports at high altitude, where relative oxygen levels are lower, silicone hydrogel lenses should be recommended to deliver sufficient oxygen and prevent hypoxia.30 This might apply not only to mountaineers, but also long-distance runners carrying out altitude training.
The majority of modern hydrogel lenses can also provide adequate oxygen needs for daily wear.31 A recent study looked at the safety outcomes of a large group of patients wearing daily disposable hydrogel contact lenses (etafilcon A) over 12 months. Of 471 patients, there were only three adverse events (a rate of 0.6 per cent per year) with no corneal infiltrative events.32 This very low rate of complications offers confidence to practitioners when prescribing hydrogel daily disposables.
Convenience
Daily disposables are a convenient option for athletes, especially part-time wearers as they completely remove the need for solutions and cleaning. With fewer steps to comply with, daily disposables can also increase patient compliance and decrease the chance of contact lens complications such as inflammatory events and microbial keratitis.33
Practitioners should warn patients about potential risks when wearing contact lenses during water sports such as swimming. Exposing contact lenses to water during swimming, showering or in a hot tub may increase the risk of eye infection from microorganisms such as Acanthamoeba keratitis.34 General practice is to advise patients not to wear contact lenses while swimming, although some practitioners recommend using daily disposable lenses and wearing tight-fitting goggles over the lenses.The lenses should be removed after swimming. One study has shown that wearing goggles while swimming may offer some protection against contamination.35
Vision considerations for four different sports
As part of a sport vision assessment, it is important to identify the visual skills most important for the task, consider the location and speed of the object as well as environmental factors such as contrast, glare and lighting sources.
Football
Football players need excellent peripheral awareness to detect positioning of both players and the ball itself. They also need to be able to judge distances and the speed of the moving ball. Foot-eye coordination is important. Regular tests to be carried out as part of the assessment include peripheral fields assessment. More specialist tests that have been used to assess footballers include the Modified Saccadic Fixator and the peripheral awareness trainer.7 Contact lenses offer a full field of view but must give excellent visual acuity with any astigmatism accurately corrected (using a rotationally stable toric lens design).
Tennis
During a tennis game, players hit a hollow rubber ball over the net at speeds up to 160 mph.38 Players therefore need excellent dynamic visual acuity to see the ball and respond accordingly. Peripheral awareness and hand-eye coordination is also important. A vision assessment for a tennis player should include gross perimetry as well as automated field testing. More specialist tests might include the peripheral awareness trainer and the Wayne Saccadic Fixator.37 As tennis is often played outside, contact lens considerations include recommending lenses with UV-blocking properties and a full and stable astigmatic correction for excellent acuity. Wraparound sunglasses are most suitable, with a tint that reduces glare while optimising contrast so that players can easily detect the fast moving ball against its background.
Archery
Archers need excellent visual acuity to detect a target and excellent vernier acuity for alignment. Archery is one of the few sports where excellent binocular vision is not as essential since the target is often viewed monocularly. Long intervals of concentration are required for shooting and hence the blink rate is likely to decrease during these periods. When selecting a lens, the surface wettability should be considered to maintain excellent visual acuity between blinks.
Sailing
In sailing, patterns of the water and wind provide cues to boat direction and intensity and even the sensation of the wind on the face and eyes will be used to make tactical decisions in a race. Sailors must be able to make precise judgments of relative speed and distance and their eyes undergo constant changes of gaze and vergence. Routine testing for sailors might include contrast sensitivity as well as accommodative and vergence facility and peripheral vision.39 Specialist testing may include colour preference and light sensitivity. Contact lenses should include the highest level of UV-blocking available, to protect from incident and reflected UV radiation (up to 30 per cent is reflected from water)40 while offering optimal vision and comfort in challenging, sometimes windy and salty, environments. Sunglasses should reduce maximum glare, and be wraparound in design with polarising lenses. A hydrophobic surface coating may be beneficial also.
Sports vision – where to next?
This article has provided an introduction to sports vision assessment and equipment, some key considerations for fitting contact lenses for sportsmen as well as visual considerations for four popular sports. Table 2 summarises some key tips when conducting eye exams in routine practice.
Everyone need not be a sports vision expert to have some involvement though. As eye care practitioners we can maximise visual performance for our patient’s lifestyle through routine optometry. We can give our sporting patients many benefits just by offering them contact lenses. By carrying out a thorough history, asking careful questions about our patient’s requirements and environment we can be best placed to understand and then advise on how to maximise their visual performance in their chosen sport. Discussing appropriate vision correction options, including eye protection and sun protection for all of their activities can improve patient satisfaction and grow patient loyalty as well as expand your practice.
Case study: Joe Cole
Joe Cole is a midfielder who has played more than 360 premier league football games and scored 45 goals. A technically gifted player with exceptional creativity to unlock a defence, Cole has played for both Chelsea and Liverpool as well as for England in three World Cups. He will play for Aston Villa next season and will be watching the FIFA World this year with interest. In a recent interview he described the importance of vision for top performance in football and his experience with contact lenses.36
In football, vision has the potential to affect everything from clarity of sight to the ability to perform specific tasks and information processing. Cole says vision is the starting point for football – ‘You have to see the ball early so you can anticipate the next move. We are constantly moving our heads in the game and seeing things before they happen. Good vision is vital for getting results.’
Football players need excellent visual acuity, contrast sensitivity and full peripheral vision. ‘As a midfielder your peripheral vision is massively important and wearing contact lenses really opened up the pitch to me, improving my ability to spot more passes, see runs from team mates and find dangerous spaces.’
Cole started wearing contact lenses for football in his mid 20s after it was detected at a routine medical at Chelsea that he needed vision correction. ‘I started experiencing headaches and was told I’d need vision correction. Realistically contact lenses where the best option for my profession.’ He says it made a massive difference and improved his game dramatically. ‘I would never have been able to play for England without them.’
Cole has worn daily disposable contact lenses 1-day Acuvue Moist for most of his football career. ‘I never play without my contact lenses now, and they are the first thing I pack along with my shin pads and boots. It makes a massive difference especially at the end of the game when you get a bit dehydrated, that is when I used to get tired.’ At the end of the match is when it’s important that a footballer’s vision and comfort remains optimal for peak performance.
‘It was a huge dream come true to play for my country in the World Cup. All eyes are on you and you just want to play the best game of your life and do something people will remember you for. For that you need to be in peak condition, mentally and physically. Your eyes are just as important as your metatarsals, believe me.’
? Ella Ewens is medical affairs manager at Johnson & Johnson Visioncare, UK & Ireland
Helpful resources
1 UK Sports Vision Association – sportsvision.co.uk
2 American Optometric Association – Sports Vision Section – aoa.org/optometrists/membership/aoa-sections/sports-vision-section?sso=y
References
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