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Sport


Introduction

A significant proportion of the population participates in sports or leisure-time physical activities. For example, a world-wide metaanalysis found that among adults, walking was the most popular activity in the Americas (19% of the population), Eastern Mediterranean (15%), Southeast Asia (39%) and Western Pacific (42%). In Europe and Africa, soccer (10%) and running (9%), respectively, were top activities ( ).

Sport and recreation are often cited as the reason for seeking contact lenses. surveyed 1573 people engaged in sport and found that contact lens penetration in the sample was 18.7%. Contact lenses were reported to be the favourite system of correction among people interviewed, compared to spectacles and refractive surgery.

With modern contact lens technology, there is no reason why an ametropic sportsperson cannot compete with a normally sighted opponent on an equal basis from the standpoint of visual function. For example, daily disposable lenses offer flexibility and convenience for those playing sports. They are available in hydrogel and silicone hydrogel materials and in a wide range of parameters that will correct almost all potential sportspersons.

This chapter presents an overview of factors that should be considered when prescribing contact lenses for those participating in various sports. Although the emphasis is on competitive sports, the principles outlined are applicable to all forms of sport and recreational activity.

Deciding on the Best Form of Correction

The primary vision correction options are soft contact lenses, rigid contact lenses, orthokeratology, refractive surgery or spectacles. Rigid lenses can be made in corneal, corneo-scleral or scleral designs. Scleral lenses are usually prescribed only in very demanding circumstances; they will therefore not be considered in detail in this chapter (see Chapter 17 ).

Refractive surgery represents the most radical alternative. The benefits are that no correction needs to be worn for sport, and problems of lens loss, lens movement and lens maintenance are obviated. Although it might seem to be a perfect solution, laser correction is not without potential drawbacks. Corneal haze and regression can lead to less than perfect visual acuity, especially during the first few months following surgery. There is also potential for flap damage in patients who have had laser in situ keratomileusis (LASIK). reported on a case where the left eye of a 39-year-old man was struck by the finger of a friend while the two were practising karate, resulting in loss of the flap, which occurred 3 years and 5 months after LASIK. noted that a 38-year-old man sustained a dislocated flap after being struck in the left eye with a football more than 30 months after uneventful LASIK. These cases illustrate the need for LASIK patients to wear protective eyewear when participating in contact sports.

A comparison of the key features of the primary options for vision correction for sport is presented in Table 24.1 .

Table 24.1
Comparison of Different Forms of Vision Correction for Sport
Characteristic Soft Lenses Rigid Lenses Orthokeratology Spectacles Refractive Surgery
Field of view Full Full Full Restricted Full
Stability of vision (postblink) Excellent Good Excellent Excellent Excellent
Glare None In low light None None Some postsurgery
Glare protection tint possible Cosmetic only No No Yes N/A
Ultraviolet protection possible Yes Yes No Yes N/A
Initial comfort Good Poor Fair Good Fair
Long-term comfort Good Good Excellent Good Excellent
Adaptation required Very little Yes Yes Sometimes N/A
Suitability for intermittent use Yes Not usually No Yes No
Disposability viable Yes No N/A No N/A
Risk of loss Low Moderate N/A Low N/A
Risk of dislodgement during wear Low Moderate Nil High N/A
Risk of damage during wear Low Low Nil High Moderate (LASIK flap mislocation)
Risk of damage with handling High Low Low Low N/A
Ease of care Simple (nil for daily disposable) Simple Simple Simple N/A
Initial cost Low Moderate High Moderate High
Ongoing costs High Moderate Moderate Nil Nil
Cost to correct astigmatism High Low Only limited correction possible Low High
Bifocal correction possible Compromise Very difficult No Yes Monovision
Use in rain Good Good Excellent Poor Excellent
Susceptibility to fog up No No No Yes No
Susceptibility to dirt up No No No Yes No
Risk of complication Low Negligible Low None Moderate
LASIK , Laser in situ keratomileusis; N/A = not applicable.

Do Contact Lenses Enhance Sporting Performance?

Some clinicians have offered the anecdotal opinion that, compared with spectacles, contact lenses enhance the visual skills of the ametropic sportsperson; however, properly controlled clinical trials do not support these claims. applied a battery of tests (including measurement of high- and low-contrast visual acuity, assessment of lens fit and subjective assessment of visual performance) to ametropic athletes wearing their spectacle correction versus low-water-content soft contact lenses. The authors found that, although contact lenses did not offer a measurable advantage over spectacles in terms of visual performance under these testing conditions, the psychological advantages were significant, and in this way, contact lenses may enhance overall sports-oriented visual performance.

There have been suggestions that specially tinted contact lenses can enhance sporting performance. For example, have demonstrated that the now-discontinued Maxsight Amber lenses (50% visible light transmission) and grey-green lenses (36% visible light transmission) provide better contrast discrimination in bright sunlight, better contrast discrimination when alternating between bright and shaded target conditions, better speed of visual recovery in bright sunlight and better overall visual performance in bright and shaded target conditions compared with clear lenses. However, the extent to which these visual performance attributes translate to enhanced sports performance is less clear ( ). The prescription of performance-enhancing tinted contact lenses for sport is discussed further in Chapter 21 .

Environmental and Physical Constraints

The choice of contact lens for use in a given sport must be made with reference to the length of time that it takes to play the sport, the environment in which it is played and the general physical demands of the sport. The majority of sports are completed within 2 hours, which equates to a total period of lens wear of 4 hours, allowing for pre- and postmatch activity during which lens insertion and removal would be impractical and/or undesirable. Even when these factors are understood, the lens of the first choice may not be obvious. The most appropriate lens is sometimes determined only by trial and error.

Environmental Conditions

Contact lens wear is often associated with signs and symptoms of ocular dryness. These drying effects can be exacerbated by certain environmental factors, such as low humidity, wind and visual tasks. Wearing silicone hydrogel contact lenses may provide greater relief of subjective ocular discomfort in adverse environmental conditions than that afforded by both the habitual lenses of contact lens wearers or no contact lens wear ( ).

Sports are played in almost every environment. Climatic conditions play a role in disease severity and causative organism in contact-lens-related microbial keratitis and therefore have implications for practitioners involved in contact lens care of wearers who may be engaging in sporting activities in the tropics ( ). The following environmental conditions are considered as they will directly affect the choice of lens for the sportsperson.

Cold

Many sports take place in cold environments, typically in close proximity to ice and snow. Because the intrinsic temperature of the eye and tear film is around 34°C ( ), contact lenses cannot freeze up in the eye. In an extensive survey of 105 contact lens wearers who were frequently engaged in cold-weather sports, found no evidence of eye injury or disease. ‘Eye redness’ was the most common complaint of rigid lens wearers; soft lens wearers most frequently complained of slightly reduced vision. Large-diameter, medium-water-content hydrogel or silicone hydrogel soft lenses may provide the best results in cold conditions.

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