Epidemiology of sports-related ophthalmology issues

Sports-related ocular/orbital injuries have generated considerable interest and research. Identifying common ophthalmology health problems in sport, their severity, risk factors and mechanisms, ideally through well-designed prospective cohort studies, are forming the basis for developing targeted preventive strategies—see the four-step model of van Mechelen et al,4 often applied in health epidemiology.

Sports-related ocular injuries are present across individual and team sports. Most of the literature on epidemiology has collected data retrospectively through medical databases in hospitals and emergency departments.

Eye trauma is typically a result of traumatic accidents following crashes or (un)intentional contact with an opponent or equipment. Although most sports-related eye injuries from blunt trauma have relatively good visual outcomes, several blunt traumas result in more severe orbital/intraocular sequelae. These will require follow-up and management.5

We must distinguish between penetrating and perforating injuries. Penetrating injuries occur when there is a single laceration to the eye, causing an open globe. Perforating injuries are when two full-thickness lacerations are present,6 usually resulting from sharp objects.

Sports may be classified as high, moderate and low risk for eye injuries7 (table 1). Another more mechanical definition classifies sports into high energy and low energy with respect to the projectile hitting the eye, injuries and penetration.

Due to the varying popularity of sports worldwide, there are also geographical variations in ophthalmology health issues. While some of the available research focused on single sports,8 9 other research investigated multiple sports,10 11 but with no or limited long-term follow-up of eye injuries.

Prospective studies systematically quantifying and characterising the incidence and type of injuries seen with sports-related ocular trauma are scarce.12–17

A limitation of the current research is that datasets often rely on emergency department data, which may only collect the most severe injuries (eg, National Electronic Injury Surveillance System).18 In addition, many studies reported on the most commonly presented eye issues as absolute numbers rather than as relative proportions, meaning that when a sport is popular in a specific country, it is not surprising that those sports stand for the most injuries.

Sports-related ophthalmology issues in Olympic Games: Anecdotally, following 10 years of data collection across three Summer and three Winter Olympic Games and three Youth Olympic Games, few severe eye injuries have been documented.13 Eye injuries thus seem infrequent during the Olympic Games, though we lack reliable data. Currently, the IOC research methodology does not allow sports medicine physicians to report eye injuries,19 as ‘Face reliably’ is the broad injury location category for National Olympic Committee physicians to capture eye injuries. However, a new category to record ophthalmology-related illness issues has been added to the reporting sheet/database.20

Anatomy for sports medicine physicians

Proper clinical care of sports-related ophthalmology issues requires a good understanding of anatomy and common ocular conditions associated with high-level sports, including proper examination techniques by the sports medicine physician.

Externally, the upper and lower eyelids cover the eye. In addition, tear fluid produced in the lacrimal gland under the outer part of the frontal bone protects the ocular surface.21 The tear fluid is then drained from the upper and lower puncta medially on the eyelids into the lacrimal canaliculi, the lacrimal sac and further into the inferior nasal meatus of the nasal cavity (figure 1A).

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Figure 1

(A) Eye anatomy: ocular surface; (B) eye anatomy: orbital content; (C) eye anatomy: division of the eye; (D) eye anatomy: retina.

The orbital bones consist of the frontal, zygomatic, maxillary, sphenoid, lacrimal and ethmoid bones forming a four-sided eye protection (figure 1B). Together with the orbital septum (palpebral fascia) anteriorly, this forms a closed compartment with orbital fat providing structural support to orbital structures.21 The medial orbital wall also contains a fragile part, lamina papyrica, vulnerable to trauma and the spread of infections from the sinuses and into the postseptal orbital compartment.

The extraocular muscles arise from the orbit and insert into the eyeball, allowing ocular mobility. These muscles are innervated by the cranial nerves n. abducens (abduction of the eye), n. trochlearis (downward gaze from adducted position) and n. oculomotorius (controlling most other eye movements, constricting the pupil and the levator palpebrae muscle). The optic nerve and the ophthalmic artery also pass through the orbit through the foramen ovale, and the periorbital fat protects the orbital structures.21

The eye globe is divided into three separate layers (figure 1C); the outer layer (tunica fibrosa) consists of the viscoelastic white sclera and the cornea, uvea (tunica vasculosa) consists of the iris, ciliary body and choroid and the innermost layer (tunica interna) consists of the retina and the retinal pigmented epithelium (RPE). The eye can also be divided into an anterior and posterior segment. The anterior segment includes the clear cornea, anterior chamber, iris/pupil and lens. In addition, aqueous humour is produced by the epithelium lining the ciliary body and flows into the anterior chamber, where it is drained from the eye into the trabecular meshwork. The posterior segment includes the vitreous, choroid, retina and optic nerve head.21

When light enters the eye (figure 1D), specialised photoreceptors in the retina generate an electrical signal. Rods are mainly found in the peripheral areas of the retina and are responsible for night and peripheral vision. In contrast, cones are mainly clustered in the macula, providing sharp central and colour vision. The generation of electrical signals and processing by the neural network in the retina has the highest oxygen consumption per weight of all tissues in the body, indicating a high metabolic rate. Thus, the retina also has a dual blood supply through the central retina artery (inner retinal layers) and the choroid (outer retinal layers).22 In addition, the RPE has important supporting functions essential to photoreceptor maintenance, including the transport of nutrients from the choroid to the retina and phagocytosis and removal of the outer segments of the photoreceptors.23

The electrical signal from the retina is then transferred into action potentials by the retinal ganglion cells and travels along the optic nerve to the brain. The optical fibres nasally cross at the optic chiasm so that all signals from the right visual field end up in the left visual cortex and from the left visual field into the right visual cortex.21

Trauma to the orbit, adnexa and eye globe

Eye globe injuries are classified according to The Birmingham Eye Trauma Terminology system24 and there are several classifications for facial and orbital fractures,25 but there is no single classification combining orbital fractures, periorbital and eyeball injuries.

Depending on the energy and area of impact of the trauma, the following can be encountered:

1. Periorbital tissues: swelling and lacerations of the eyelids.

2. Eyeball: conjunctival bleedings, corneal abrasions, perforation, hyphema (accumulation of blood in the anterior chamber), iridodialysis (separation of the iris from the ciliary lens subluxation/luxation), lens luxation or traumatic cataract, choroidal and vitreous haemorrhages, commotio retinae, retinal tear/detachment.

3. Orbit: fracture of orbital bones, traumatic optic neuropathy, optic nerve avulsion, compartment syndrome due to intraorbital haemorrhage.26 The zygomaticomaxillary complex fracture is the most commonly encountered sports-related orbital fracture.27 The roof of the infraorbital canal located in the orbital floor and lamina papyracea in the medial wall are the thinnest and weakest parts of the orbit, and most of the fractures pass through these sites.27

The sideline evaluation of the eye should include visual acuity, pupillary shape, size and light reflex, always comparing to the fellow eye, meaning the other eye. Absent red reflex (reddish-orange reflection of light from the retina) mandates a specialist examination. Diplopia, exophthalmia/enophthalmia, orbital rim step-off and numbness over the cheek can indicate a bone fracture.26 27 It is generally agreed that entrapment of an extraocular muscle, particularly trapdoor fractures in children accompanied with bradycardia, syncope or vomiting (oculocardiac reflex), cosmetically significant exophthalmos or hypoglobus and large orbital floor fractures (more than 50% of the surface area) requires early surgical attention.26 28

Special attention should be paid to the following particular conditions:

1. The lacrimal drainage system will likely be damaged if a laceration involves the medial eyelid margins. A specialist, for example, oculoplastic, must handle these cases.

2. Open globe injuries are susceptible to infections, and an intraocular foreign body must be ruled out using a CT-only. MRI cannot be used because of possible magnetic intraocular material risk. Ocular ultrasound must also not be used due to the increased risk of pressure-induced damage from the probe.

3. Loss of vision and lack of ocular motility can be a sign of orbital compartment syndrome, which should be treated immediately.

A special type of relatively common injury deserving close attention is the blow-out fracture, which occurs secondary to a sudden explosive increase of the intraorbital pressure transmitted to orbital bones, most often due to high-velocity ball-related injuries. The floor is the most vulnerable part of the orbit, but the orbital rim usually remains intact.29 Blow-out fracture must be considered in the presence of typical signs and symptoms, which include diplopia (on upward gaze), limited upward gaze, tenderness at the infraorbital rim, decreased sensation over the inferior orbital rim, extending to the edge of the nose and ipsilateral upper lip (indicates infraorbital nerve injury).29 30 Subcutaneous or orbital emphysema and crepitation may suggest a fracture of the maxillary sinus or breach in the lamina papyracea. Decreased visual acuity and an absent pupillary light reflex may indicate orbital haemorrhage or optic nerve injury.29 30 In these instances, CT of the orbit is mandatory and may show the fracture lines, air-fluid level or haemorrhage in the maxillary sinus, and herniated orbital contents into the maxillary sinus (figure 2).29 30

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Figure 2

CT scan of a tennis player who received a direct hit of the ball to the left eye. (A) Coronal view: there is a large bony defect in the medial part of the left orbital floor with herniation of the inferior rectus muscle and orbital fat into the maxillary sinus (arrow). (B) CT scan of a tennis player who received a direct hit of the ball to the left eye, sagittal view.

Most specialists agree that surgery must be undertaken within 14 days to prevent fibrosis if indicated.31 In the acute phase, corticosteroids may help dissipating oedema, and the patient must be warned against forceful nose-blowing and refrain from any Valsalva manoeuvres requiring action. Prophylactic oral antibiotics are recommended.29–31 The outcome of blow-out fractures is variable. The recovery is slow; many patients may experience persistent neuralgia, diplopia and enophthalmos. Ocular motility exercises must be instituted early to stimulate the regeneration of orbital septa connecting the extraocular muscle.30

Targeted history and assessment of the athlete’s eye

Other relevant eye conditions affecting sports activity and performance

The ocular surface of the eye

Ocular surface diseases (OSDs) encompass a range of pathologies involving the structures and tissues dedicated to the interface between the environment and the highly sensitive external ocular tissues. These protective tissues are of paramount importance, and sight-threatening manifestations may occur in case of loss of both local and extraocular homeostasis and impaired protection sensors (figure 3).

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Figure 3

Ocular surface diseases encompass a range of pathologies involving the structures and tissues.

Adverse environments play a major role in inducing or aggravating dry eye symptoms and OSDs. Dry, windy or dirty environments, air conditioning, blue light and ultraviolet (UV) exposures, pollution, and high altitude, may cause various effects on the ocular surface through oxidative stress, inflammatory, allergic or toxic mechanisms. Video display terminals play a particular role in associating adverse environments, blue light exposure, ocular fatigue and reduced blinking rate.39 40 Other interventions such as chronic use of eye-drops, especially if containing preservatives,41 contact lens wear or refractive surgery are important risk factors of OSD.

Dry eye disease (DED) concerns up to 15% of the general population and approximately 50% of people working or gaming in front of a VDT,42 43 which potentially concerns all electronic sports (Esports) athletes to a level that is still not fully recognised (see paragraph on Esports).

The main consequence of DED is a significant decrease in quality of life (QoL). The symptoms of dry eye, such as sensations of discomfort, foreign body, burning, fluctuating visual disturbances, or tearing, initially intermittent, can become permanent and deeply alter the patient’s QoL and performance.44 DED has thus been shown to impact the QoL at levels comparable to angina pectoris grade III/IV.45

Studies on large cohorts of patients have shown that dry eye significantly negatively impacts many daily activities, such as reading, using a computer, watching television or driving day or night.45 Beyond this impairment of QoL, dry eye is associated with psychological disorders such as anxiety and depression.46

All these elements, symptoms of discomfort or pain, fluctuating vision, glare or even photophobia, are directly influenced by the environment. Athletes can, therefore, be particularly sensitive to the environment they are exposed to. Even more at risk are those individuals who suffer from pre-existing ocular surface pathology: dryness, contact lens wear, skin diseases (eg, seborrheic or atopic dermatitis, rosacea) or allergies. Refractive surgery is of particular significance among the specific risk factors potentially encountered in the sports population. The athlete can, thanks to these procedures, participate in sport without glasses or contact lenses with an undeniable benefit, but dry eye induced in particular by the transection of the corneal nerves can affect up to 30% of individuals with sometimes persistent severe symptoms, and even neuropathic pain that is very difficult to relieve.47 Several cases of suicide have been reported and publicised in the USA, precisely for chronic post-LASIK pain.47

Regarding dry eye and ocular pain therapies, preservative-containing tear substitutes, largely available in OTC, should be avoided as preservatives may aggravate tear instability and cause toxic side effects. Care should be taken to avoid potentially forbidden treatments, like steroids or hormone therapy, cannabinoids or other pain-relievers.

Prevention

Ninety per cent of all sport-related ocular injuries are preventable with suitable eye protection.69 70 The World Squash Federation (WSF) World Championship regulations require juniors (under 9 years) playing any WSF Team Championship or any WSF Junior Individual Championship to wear appropriate eyewear. No reports of significant ocular injuries have been published subsequently.70 Visors have decreased the incidence of eye injuries in ice hockey.6 71–73 Protective eyewear (goggles) significantly reduced eye injuries in high school hockey and squash.74 ,75 76

Several Nordic and central European countries have a special interest in floorball eye trauma due to its high prevalence.8 74 77 For example, in a Finnish study, 17% of all eye injuries were sports related, and 45% were caused by floorball.8 Due to these findings, the Finnish Floorball Federation made protective eyewear mandatory in junior floorball. Educational interventions can be beneficial by spreading information about the importance of using safety equipment. By modifying the sport’s rules and promoting safety measures, sports‐related eye injuries and consequent visual impairments and blindness can be prevented.

The American Academy of Pediatrics and Academy of Ophthalmology strongly advocate using eye protection in sports, which carries the risk of an eye injury.26 78 79 Eye protection in sports should be mandatory in functionally one-eyed athletes and after eye surgery.

Overall recommendations published by Dain7 include all International, National and regional standards of eye protection in sports and reveal a high heterogeneity between regions and sports in relation to eye protection.

Recommended eye protection for sports will be provided by either faceguards/visors (attached to helmets) or sports eye guards (goggles or spectacles). Polycarbonate lenses must be used with protectors that meet or exceed the requirements of the current sport-specific ASTM (American Society for Testing and Materials).

Vision and performance

Vision, just like speed and strength, is a critical component in elite sports performance. Vision generates stimuli that can enhance eye-hand coordination making it essential for successful sports performance. However, athletes, in general, rarely consider or train vision. There is also very limited research regarding performance benefits for elite competitors. Nevertheless, the theoretical role of the visual system, areas of the brain that employ vision to make decisions, and how decisions are integrated to generate an intended motor response potentially leading to improved performance can be illustrated by the sports vision pyramid (goal, visual integration, monocular sensory processes, binocular sensory processes, neural processing).2 80

All five levels of the pyramid depend on appropriate input from other levels. It is proposed that correcting or training any one level without optimal information from a level below will impact performance negatively.80 The lowest level of the pyramid begins with the basic visual abilities of each eye, termed ‘monocular sensory processes’, which include visual acuity and contrast sensitivity. Visual acuity is the commonly known score (eg, 20/20 or 20/30), while contrast sensitivity describes the ability to pick out a target from a similar low-contrast background.80 Also relevant to elite sports performance is presentation time, that is, seeing a target for a fraction of a second (eg, shooting). The input of basic visual information from both eyes is integrated and processed to appreciate the depth, which is critical to many sports. According to the sports vision pyramid, the neural processing level concerns how the basic visual information is used and processed to make a decision heavily influenced by an athlete’s prior experience. Once a decision is made, the visual information must be coordinated with hand, foot and body movements to carry out a task. Interventions range from excimer eye laser treatment, glasses or contact lenses to correct problems with visual acuity at the base of the pyramid, to the training of hand/eye/foot coordination, or the ability to track multiple targets at the upper levels. Understanding and evaluating the visual ability needed at each level for each sport (and position within a sport) and then correcting deficits will be necessary for sustained high-level performance. The main testing methods that can be applied to elite sports are described in Table 1 in online supplemental appendix 4.

There are anecdotal accounts that some athletes possess a kind of enhanced visual perception that allows them to eliminate any distractions as they plan their next move, especially during times of stress—a phenomenon known as ‘quiet eye’.81 The quiet eye represents one of the most well-studied visual strategies in sports. It is defined as a gaze behaviour that differentiates expert-novice performance from successful and unsuccessful performance in experts.81 Inevitably, differences in vision and visual-motor coordination skills between athletes and non-athletes exist, and it remains to be determined whether perceptual-cognitive differences between athletes and non-athletes can be explained fully by the quiet eye idea alone.

Shooting is one example of a sport where vision plays a paramount role in performance. Shooting requires intense focus, concentration and precision, further compounded by the pressure of competition, spectators and the allotted time to make the shot. It is not surprising, therefore, that improving key visual skills such as the ones described in online supplemental appendix 4, table 2 can lead to significant increases in performance.

There is much anecdotal support for the idea that strong visual skills are just as important to an athlete’s success as conditioned skeletal muscles. As with this link between vision and performance, there is a good theoretical underpinning for visual training to improve sports performance. However, whether vision training has a direct transfer to the sport-field setting remains unclear according to the field of science, but several performance metrics following visual training, both sport-specific and non-sport-specific tests, exist. For example, a group of hockey players who participated in a 6-week sports vision training programme improved the visual tasks used in training. At the same time, no improvements were found on a separate transfer task82 The finding that non-sport-specific vision training period could induce significant performance improvements, was also confirmed in another study involving a tennis field-based test.83 Generalised vision training improved some measures of visual skills, but not all studies did find vision training to improve performance.84 These studies that find a positive effect of generic vision training on sport-specific metrics attribute this finding to the ability of visual training to inhibit attention to task-irrelevant or distracting stimuli.82 83 85 86 Further studies involving vision training, both sport-specific and non-sport-specific, conducted in elite athletes and examining performance in real competition is needed to more definitively resolve the question of the impact of visual training on performance before vision training becomes a mainstay of training and preparation of the elite athlete. This advance will also require larger, better-designed, powered studies with consistent and precise outcome measures.1 Table 3 in online supplemetal appendix 4 describes some of the most commonly used training modalities elite athletes use.

Given the good theoretical underpinning and some evidence linking superior vision and vision training and performance, research on components that help improve vision in sports but also minimise the associated risk of injuries should be encouraged. This collective knowledge, when made available for the athletes, coaches, medical professionals and the larger sports ecosystem to build on further, would help safeguard athletes’ physical health and promote high-level performance.

Equity, diversity and inclusion statement

A diverse expert panel of authors consisted of sports medicine physicians, former Olympic athletes as athlete representatives, sports physiologists, sports scientists and mental performance consultants. Authors were invited based on their expertise, as demonstrated by previous research and clinical experiences with Ophthalmology. In total, 3 females and 12 males from 4 continents participated.