Other relevant eye conditions affecting sports activity and performance
Visual symptoms following concussion
Traumatic brain injury (TBI) is the primary cause of trauma-related long-term or permanent disability worldwide. It is categorised as mild, moderate and severe, with 90% of all TBIs being mild to moderate.33 In a mild TBI (mTBI), the most acute symptoms are headache, nausea, dizziness and double vision. Approximately one-half of the brain is devoted to visual processing, and deficits in eye movement and affect recognition are among the impairments reported to arise from mTBI.33 With mTBI, both the afferent and efferent visual pathways can be damaged, disrupting vision.
Sport-related concussion (SRC) is a subset of mTBI and accounts for 20% of all TBIs.32 SRC is an evolving injury in the acute phase, with rapidly changing clinical signs and symptoms, which may reflect the underlying physiological injury in the brain and is among the most complex injuries in sports medicine to diagnose, assess and manage.34 These symptoms can be cognitive, physical, emotional and sleep disturbances. Overall, 80%–90% of SRCs typically resolve within 7–10 days.34 35 However, symptoms can persist for weeks to months in a small subset of athletes. Nearly 30% of concussed athletes report visual problems during the first week after the injury36 and the visual impairments can be caused by accommodative, oculomotor and binocular dysfunction. Visual processing can be disrupted and create issues with balance and hand-eye coordination. Vision can be compromised because of injury to one or both optic nerves, impaired visual processing in diffuse brain injury, or limitation in eye movements because of dysfunction of cranial nerves.37 Ocular motor impairments and symptoms may manifest as blurred vision, diplopia, impaired eye movements, dizziness, photophobia, headaches, ocular pain, difficulty in reading and poor visual-based concentration. Among the most common of these are photophobia and its migraine-like symptoms. Dizziness, which may represent an underlying impairment of the vestibular or ocular motor systems, is reported by 50% of concussed athletes36 and is associated with a 6.4- times greater risk in predicting protracted (>21 days) recovery.38 Prolonged recovery can also be seen when fogginess and blurred vision are present.
Sports medicine physicians are uniquely positioned to diagnose, manage and treat SRC. The need for a multidisciplinary team is widely accepted and viewed as a critical approach to treating SRC’s multifactorial signs and symptoms (online supplemental appendix 2—Vestibular/Ocular-Motor Screening).
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).
Figure 3Ocular 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.
Ultraviolet light exposure and the athlete’s eyes
Besides acute trauma, sports medicine physicians should also be mindful of injuries from excessive exposure to UV light. Sports at increased risk include sailing, surfing and snow sports, where UV rays are reflected off the sea surface and snow, amplifying the exposure.48 49 Excessive UV exposure to the eyes increases the risk of photokeratosis (snow blindness), pinguecula (protein and fat deposits over the sclera, causing eye irritation and disrupting the tear film), pterygium (surfer’s eye, a soft tissue growth that extends from the sclera to the cornea, creeping into the visual axis in severe cases), cataract, basal cell carcinoma and squamous cell carcinoma of the eyelids, and to some degree also the risk for age-related macular degeneration.50–52 However, in adulthood, exposure of the retina to UV radiation is reduced due to decreasing transmission properties of the natural lens.53 These risks can also be effectively reduced using UV-blocking sunglasses and hats.48 49
Sports-related ophthalmology issues in electronic sports
Esports is a developing area in medicine; however, half the world’s population (3+ billion) are estimated to play games regularly. Esports is organised, competitive video gaming and is a worldwide phenomenon. To remain competitive in this popular and sometimes lucrative field, gamers often practice 12 hours daily, performing anywhere from 400 to 600 actions per minute.54 For an esports athlete to perform at an elite level for extended periods, it requires advanced motor skills, mental agility, processing speed, executive function, motivation, and, to a lesser extent, physical exertion. Esports can be played on a personal computer, gaming console (Xbox/PlayStation/Nintendo), mobile device or a head-mounted display. Attention to the needs of gamers and esports athletes has become more prevalent over the past few years with the growth of the industry and the number of professional leagues being established. These needs include optimising visual, mental and physical health and performance, whether casual or professional gaming.
Ophthalmologists and sport medicine practitioners are well positioned to expand their scope of practice into Esports, given the visual, mental and physical demands of gaming.
Visual demands of gaming are inherent and obvious, as one needs to interact with screens at near distances for extended periods constantly. Gamers are experiencing symptoms of blue light toxicity, digital eye strain (asthenopia), also referred to as computer vision syndrome (CVS), including blurred vision, dry eye, photophobia, double vision and uncontrolled blinking (blepharospasm).55 Non-ocular symptoms associated with eye strain include a stiff neck, general fatigue, headache and backache. The opportunity to educate gamers on proper digital hygiene (20/20/20 rule), identify technologies to monitor vision performance, including the vision performance index (VPI), and treatment options for digital eyestrain as an Esports eye care practitioner are becoming practical and necessary.
Ninety per cent of computer users, who spend more than 3 hours a day in front of the computer screen, suffer from CVS.57 Its multifactorial pathophysiology includes ocular-surface abnormalities, accommodative spasms and ergonomics. A general rule of visual ergonomics that can be effective for gamers to help reduce eye strain is the 20-20-20 rule, which instructs them to briefly look away from the screen for at least 20 s to a distant scene at least 20 feet (6 m) away after every 20 min of continuous screen time. Treatment for CVS can include preservative-free lubricating drops, correction of accommodation issues and astigmatism with optical lenses with different coatings or prisms, improving ergonomics with proper positioning of the gaming set-up and chair, optimising ambient lighting and reduction of blue light with filters, screens and lenses.
The VPI is a holistic assessment tool for measuring, analysing and monitoring vision, cognition and motor function while engaging in interactive media. The VPI is readily accessible through games and other interactive software applications. The VPI comprises over 100 psychometrics generated from user response to stimuli during gameplay,58 and measures 5 dimensions across vision, cognition and motor function. These dimensions include:
Field of view—Identifying stimuli in the central and peripheral field of view.
Accuracy—Decision-making between targets and distractors, along with intentional movements and reaction time to those targets.
Multitracking—Attention and multitasking, involving focused and divided task execution.
Endurance—Ability to perform over time with measures of fatiguability and recoverability.
Detection—Distinguishing features between stimuli, including size discrimination, colour and contrast.
The VPI dimensions allow esports athletes, coaches and trainers to identify strengths and weaknesses, monitor the therapeutic effects of interventions to improve performance and personalise training programmes to game/role-specific skill sets.
With the evolution of the esports industry, Esports medicine will continue to grow. The need for education and awareness of CVS, implementation of preventative eye health strategies and promotion of healthy digital lifestyles for gamers, healthcare practitioners and other key stakeholders are paramount for this emerging field. Additionally, damage to the retina with extended screen time, blue light exposure and increased rates of myopia are areas of concern for esports athletes and gamers. Along with advancements in research on the effects of screen time on the visual system, there will be a significant opportunity for exploring and understanding the intimate relationship between the eye-brain-body.
Subclinical ocular pathologies affecting sports performance
Subclinical ocular pathologies and ambiguous complaints may go unnoticed and undiagnosed in the acute phase of sports injury/illness or are easily overlooked during the routine ophthalmic examination. For example, athletes may be at increased risk of intractable chronic central serous chorioretinopathy development due to the heavy physical and mental stress associated with competitive sports. The use of prohibited drugs can also increase the risk.59 Athletes may also be at increased risk of visual symptoms brought on by repeated concussion events. Hence, improved screening methods must be developed to help identify and manage visual symptoms and guide treatment and the required time for the athlete to return to sport.60–62 If accompanying pathologies such as subclinical retinal, optic nerve and mild brain abnormalities are not detected and treated properly, these pathologies affecting visual quality may also impact performance or predispose further injury.63 For example, even if the best corrected visual acuity is normal or restored postinjury, accompanying retina, retinal ganglion cells, optic nerve injuries and other brain abnormalities may impact visual performance. New and more specific technologies and examination protocols must be developed to detect better and diagnose ambiguous subclinical eye pathologies that will undoubtedly impact vision and, therefore, sporting performance. Multimodal imaging techniques such as optical coherence tomography angiography,64–66 digital vision screener and electrophysiologic tests (eg, retinal function analyzer)67 68 are some of the approaches being trialled and tested to comprehensively evaluate the structural and functional components of the visual pathways for more appropriate diagnosis and treatment of visual impairments. Such developments with particular relevance to identifying visual impairments and ambiguous subclinical eye pathologies in sports must be accelerated.