A Systematic Review on the Effectiveness of Eyewear in Reducing the Incidence and Severity of Eye Injuries in Racket Sports

ABSTRACT

Purpose

To assess what eyewear (if any) reduces eye injury incidence and severity in squash, racketball, tennis and badminton.

Design

Systematic review following the ‘Preferred Reporting Items for Systematic Reviews and Meta-Analyses’ (PRISMA) and the ‘implementing Prisma in Exercise, Rehabilitation, Sport medicine and SporTs science’ (PERSiST) guidelines.

Methods

PubMed, SportDiscus and Web of Science were searched on 22nd February 2023. All study types except reviews were eligible. Studies had to report the type of eyewear worn (if any) with a form of eye injury incidence and severity.

Results

364 papers were initially retrieved and after the screening process 29 remained. A subgroup analysis was carried out on studies that had a sample size of five or above, were not only looking at a particular type of eye injury and that had sufficient data to allow the percentage of eye injuries that occurred when no eyewear was worn to be calculated. From this analysis, the median percentage of eye injuries that occurred when no eyewear was worn was found to be 93%. Some of these injuries were serious and required complex treatment. Prescription lenses, contact lenses and industrial eyewear made some injuries more severe. In squash and racketball, lensless eye guards were ineffective as the ball could deform on impact, still making contact with the eye. Only eyewear compliant with updated ASTM (or similar) standards was associated with no eye injuries and so provided adequate protection in all four sports.

Conclusions

Although this systematic review only summarizes evidence on injuries requiring hospital treatment, it is recommended that national governing bodies and key decision makers within squash, racketball, tennis and badminton examine the evidence presented and consider extending existing rules or implementing new recommendations and policies on protective eyewear use to reduce eye injury incidence and severity in their sport.

KEYWORDS:

• Eye Injuries
• Racket sports
• Badminton
• Tennis
• Racketball
• Squash
• Protective eyewear
• Prevention

1. Introduction

A significant proportion, 28–52%, of sporting eye injuries are caused by racket sports [1–6]. The use of rackets and the high speed of the ball/shuttlecock means these sports are classified as having a high risk of eye injury [7–9]. Another risk factor that has been identified is the proximity of players during play [10]. This is because when players are closer together, if they are hit by a ball/shuttlecock, the impact is likely to cause more damage as there has been less time for the ball/shuttlecock to decelerate before impact [10,11]. It could be argued that this risk is not present in badminton and tennis as a net separates the players, unlike in squash and racketball. However, when playing doubles (particularly in badminton) the risk of serious injury increases [12], probably due to the fact two players are on the same side of the court with little distance between them. There is concern the increased participation in racket sports will lead to a corresponding rise in eye injuries. From 2018–2021 the number of tennis players grew by 4.5% [13], whilst badminton reported a 14% increase in adult players between 2019 and 2020 [14]. Racketball was the fastest growing sport in the UK in 2020 [15] and squash participation increased by 47% from 2013 to 2018 [16]. Without effective prevention strategies, increasing participation in racket sports is likely to lead to more eye injuries.

There are three main classifications of eye injuries experienced in racket sports [17]. These are: blunt trauma (direct impact to the eye globe, which may cause damage to the ocular adnexa, potentially leading to ‘permanent facial disfigurement’ 18, reduced movement of the eye [18] and a decrease in its functional capabilities [19]), penetrating injuries (the eye globe is lacerated) and perforating injuries (‘when 2 full-thickness lacerations (entrance and exit) are present’) 17. The injuries can also be classified as open or closed globe using the Birmingham Eye Trauma terminology [20]. Closed globe injuries involve an injury to the eye wall which has not progressed through it (for example, contusions). By contrast, open globe injuries are injuries which have completely damaged the eye wall through a rupture or laceration. These injuries are caused by various mechanisms: a direct impact of the ball/shuttlecock/racket to the eye or an impact of the ball/shuttlecock/racket to the player’s eyewear causing it to break resulting in an injury to the ocular area. Fong [1] reported squash balls and badminton shuttlecocks can travel around 220 km/h while tennis balls can reach 190 km/h. In addition, squash rackets can be swung at speeds of 150-190 km/h [1]. These are extremely high speeds and so it is understandable eye injuries occur if inadequate protection is worn. There is debate as to whether rackets or the ball/shuttlecock cause the majority of injuries, but most studies suggest impact from the ball/shuttlecock is most common [1, 5, 21–23]. In tennis and badminton this is intuitive as it is extremely unlikely to be struck by a racket in a singles match as the opponent is on the other side of a net. However, even in squash and racketball where players share the same playing area, more injuries are caused by the ball.

The injuries that are sustained in racket sports are usually minor such as corneal abrasions and lacerations [24,25] which require simple treatment with short follow ups. However, more serious injuries such as hyphaema, choroidal tears, retinal detachment, secondary glaucoma and perforation of the eyeball can occur [21,25,26]. These require longer periods of treatment and potentially surgery. In squash, the percentage of serious injuries ranges between 5.5–21% [27,28], in badminton from 14–33% [8,10,21] and in tennis approximately 7% require surgery [8]. Therefore, although eye injury incidence in racket sports is fairly low, a significant proportion require more complex treatment, highlighting the need to prevent eye injuries. In addition, losing or having impaired eyesight has a significant impact on a person’s quality of life and so it is essential any eye injuries are prevented if possible.

Several strategies have been suggested to reduce eye injuries in racket sports. These include, not turning to watch your partner’s or opponent’s shot [29,30], educating players on the risks [31], and keeping the racket in front of the face if playing at the net in badminton in case the opponent’s shot is directed toward the eyes [29]. If these are viewed in the context of ‘Hierarchy of Controls’ model [32] (as outlined by The National Institute for Occupational Safety and Health (NIOSH)), these strategies would fall under the category of ‘administrative controls’ as they involve changing the way the game is played. However, these strategies do not completely remove the risk of injury; they only reduce it. As such, eye protection is needed to further reduce the risk. Protective eyewear has successfully reduced eye injury incidence in other sports such as ice hockey [9] and so a similar strategy could be used in racket sports. Various types of eyewear are currently used. These include prescription glasses with unaltered lenses, industrial eye protectors (usually made from Poly (allyl diglycol carbonate), known as CR39), contact lenses, lensless eyewear and polycarbonate eyewear that adhered to the American Society for Testing and Materials (ASTM) standard at the time of testing (either the ASTM F803 [33] or, after 2019, the ASTM F3164–19 [34]). The purpose of eyewear is to transfer energy that would have been absorbed by the eye onto the glabella and supraorbital ridges [29]. However, certain types of eyewear are more effective. Therefore, the aim of this systematic review was to analyze the protection different types of eyewear (and lack of eyewear) provide to see which (if any) were effective at reducing eye injury incidence and severity in racket sports. This will provide an evidence base for key policy makers in each sport to inform whether protective eyewear policies or recommendations should be implemented to reduce eye injury risk.

2. Materials and methods

2.1 Data sources and search strategies

This systematic review was written following the 2020 ‘Preferred Reporting Items for Systematic Reviews and Meta-Analyses’ (PRISMA) guidelines [35] and ‘implementing Prisma in Exercise, Rehabilitation, Sport medicine and SporTs science’ (PERSiST) guidelines [36]. The review was not registered at any database and a review protocol was not prepared.

The databases searched for this systematic review were PubMed, SportDiscus and Web of Science. This occurred on 22^nd February 2023. Date and language of publication was not restricted to ensure all relevant literature was analyzed. The search strategy used in PubMed is included below. The search strategies for the other databases are in Appendix 1 (which can be found in the supplementary material of this article).

(eye injur* OR ocular injur* OR ocular trauma OR eye trauma OR ocular hazards OR head injur* OR face* injuries OR orofac* injuries OR faci* injuries) AND (racquet spor* OR squash OR badminton OR racket spor* OR racquetball OR racketball OR racquet ball OR racket ball) AND (preven* OR protect* OR eyewear OR eye wear OR goggles OR spectacles OR glasses)

2.2 Selection criteria

The inclusion criteria was developed from the PICOS framework:

Table

Population:	Tennis, badminton, squash or racketball players
Intervention:	Use (or lack of use) of different eyewear
Comparison:	Comparison between different eyewear
Outcomes:	Eye injury incidence and severity
Study types:	All, except reviews

This led to the following criteria:

1. The study had to involve players from at least one of tennis, badminton, squash or racketball.

2. The study had to report a form of eye injury incidence and eye injury severity.

3. The study had to report the use of (or lack of) eyewear.

4. The study could not be a review of any kind.

5. The study had to be written in English or the key points understood from a translation.

Initially, the titles of the papers were screened to assess whether they should be excluded. Those included after the title screening, were further screened by reading the abstract. If there was any doubt about whether the paper should be included from its abstract, the full text was read to assess its eligibility for inclusion. This process was completed by one reviewer (JM).

2.3 Data collection and synthesis

The data was organized by sport. Evidence concerning squash and racketball was grouped together given the similarity of the sports. The data recorded was:

1. The author(s) of the paper and publication year.

2. The title.

3. Key details of the study (e.g. time period of data collection, study location, the sport).

4. The data relating to eye injury incidence.

5. The data relating to eye injury severity (e.g. the amount needing hospital treatment, whether there was a permanent effect on vision after treatment etc.).

6. The data relating to what eyewear was used.

7. The data relating to the eyewear’s effectiveness in preventing eye injuries.

A data extraction sheet was created to capture this information. All data extraction sheets, with data from each individual study that was used in the review, can be found in Appendix 2 (in the supplementary material of this article). This process was completed by one reviewer (JM).

A subgroup analysis was completed on studies that had a sample size of five or more, were not only looking at a particular type of eye injury (for example, injuries occurring when lensless eyeguards were worn) and that had reported enough data to allow the percentage of eye injuries that occurred when no eyewear was worn to be calculated. This was done in order to provide an indication of how many injuries could be prevented if eyewear compliant with updated ASTM (or similar) standards was worn. The median of all the percentages was calculated to prevent lower percentage results affecting the mean.

A meta-analysis could not be completed as outcome measures from different studies were very difficult to compare. This is because it was impossible to correctly estimate the size of the population that could have obtained an eye injury in each study. Therefore, odds ratios and relative risks were unable to be calculated. Instead, for each individual study the effectiveness of eyewear was analyzed and common findings were summarized in tables. If it was not clear whether eyewear was worn in specific cases within studies, those cases were excluded.

2.4 Definition of severity

Various definitions of a severe eye injury are found in the literature. For this review, it was defined as requiring treatment from a medical professional or attending an emergency department. They did not have to be admitted to hospital.

2.5 Outcome measures

The most important outcome measure was the effectiveness of the eyewear (or lack of eyewear) used. If an injury occurred whilst wearing eyewear this demonstrated its lack of effectiveness. If a type of eyewear was completely effective, no injuries would occur. This makes it very difficult to demonstrate causality between eyewear use and a reduction in eye injuries as the perfect method of prevention would have no eye injuries associated with it. Therefore, the effectiveness of each type of eyewear was also determined by assessing the results when that specific eyewear was not used.

2.6 Assessment of quality of evidence and risk of bias

The quality of evidence and risk of bias was assessed using The Joanna Briggs Institute Critical Appraisal Tool for Case-Series [37]. This can be found in Appendix 3 (in the supplementary material of this article). This tool was used as it was created specifically to analyze case series and since all the included studies were either case series or case studies this tool was considered the most appropriate. The 10 questions were answered with a yes, no, unclear or not applicable. The responses to each question were then considered to give an overall assessment of whether the study should be included or whether further information on the study needed to be obtained. This was conducted by two reviewers (JM and DF).

3. Results

3.1 Search strategy

Figure 1 shows the details of the screening and selection process, including reasons why papers were excluded.

Figure 1. A flowchart demonstrating the process used to identify the papers eligible to be included in the systematic review. The flowchart is taken from page 5 in Page et al. (2021).[35].

Summary of included studies

The 29 studies included in the review had publication dates ranging from 1973 to 2022. There were 25 retrospective case series and 4 case studies and the data for each study was collected in a medical setting (for example, a clinic or hospital). Relevant information was taken from 14 studies for badminton, 19 for squash and racketball and 4 for tennis. Two studies provided evidence for all the sports and three studies were used to gain information on two sports.

3.3 Quality of evidence and risk of bias assessment

The results of the quality of evidence and risk of bias assessment are in Table 1. All studies were deemed eligible to be included. In several of the Easterbrook studies, items 4 and 5 (relating to consecutive and complete inclusion of participants) were recorded as unclear. This is because the data came from the Canadian Ophthalmological Society which was collated by eye surgeons voluntarily filling out questionnaires. As a result, not all eye injuries related to racket sports would be included and so there is a potential issue with inclusion of all eligible participants. However, the sample size was large enough in all the studies to warrant inclusion. Jao and colleagues [10] collected data by asking other ophthalmologists at conferences and so also has the issue of not including all the eligible population. However, 12 cases were found and provided useful information for this review. Tsui et al. [53], Wang et al. [55], Kawamata et al. [45] and Li et al. [48] have some items returned as not applicable as they are case studies. However, their findings were helpful for this review. Also, as all the evidence was collected in a medical setting this means only data on more serious injuries was analyzed. This is because if a player only sustained a minor injury, it is unlikely they would seek medical treatment. Therefore, the findings of this review need to be considered within the context that many minor eye injuries will have occurred that will not have been included.

Table 1. Quality of evidence and risk of bias assessments for the 29 included studies.

3.4 Subgroup Analysis

The median percentage of eye injuries that occurred when no eyewear was worn was 93%.

3.5 Effectiveness of eyewear

3.5.1 Eyewear in racketball and squash

The findings of the studies relating to eyewear use in squash and racketball are in Table 2. Using no eyewear or wearing prescription glasses, lensless/open eye guards or contact lenses provided no protection against eye injuries and in some cases increased the complexity of any injury experienced. However, eyewear compliant with updated ASTM (or similar) standards appeared to reduce eye injury incidence and prevent serious injuries.

Table 2. Summary of the evidence relating to the effectiveness of eyewear (or lack of eyewear) in reducing eye injuries in racketball and squash.

Type of eyewear	Effectiveness	Studies
No eyewear	Serious injuries occurred when no eyewear was worn e.g. retinal detachments and some injuries caused secondary glaucoma Some injuries required surgery and medical treatment Some injuries had a permanent impact on vision	Easterbrook 1982 [23] North 1973 [50] Capão Filipe et al. 2003 [38] Easterbrook 1981b [40] Kahle et al. 1993 [28] Jones 1987 [4] Easterbrook 1978 [39] Knorr & Jonas 1996 [47] Doxanas & Soderstrom 1980 [30]
Prescription glasses	Injuries occurred when prescription glasses were worn Lenses often shattered and led to lacerations and penetrating or perforating injuries Some injuries required surgery Some injuries had a significant permanent effect on vision Even if there were hardened glass/plastic lenses within the eyewear, some shattered and serious injuries occurred	Vinger & Tolpin 1978 [54] Fong 1994 [1] Gregory 1986 [44] North 1973 [50] Easterbrook 1982 [23] Pashby et al. 1982 [51] Kahle et al. 1993 [28] Ingram & Lewkonia 1973 [25] Easterbrook 1978 [39] Fowler et al. 1980 [43] Knorr & Jonas 1996 [47]
Lensless/open eye guards	Injuries occurred as the ball was able to deform and fit through the gap in between the rims Serious injuries occurred that required surgery and permanently impacted vision	Fong 1994 [1] Easterbrook 1982 [23] Easterbrook 1981 [40] Easterbrook 1981 [41]
Contact lenses	Hard contact lenses offered no protection and some patients required surgery after impact with a ball Soft contact lenses offerred no protection and serious eye injuries occurred when these were worn	Fowler et al. 1980 [43] Knorr & Jonas 1996 [47]
Industrial eye guards (CR39)	Some shattered when they were hit by rackets and this caused the lenses to enter the eye	Fong 1994 [1] Easterbrook 1982 [23]
Eyewear compliant with official standards such as ASTM F803 or ASTM F3164)	Number of racketball injuries drastically reduced after 1983 which corresponded with the time when many clubs made it compulsory to wear eyewear compliant with updated ASTM (or similar) standards No injuries have been reported while wearing eyewear compliant with the ASTM F803 standard Several studies recommend the use of polycarbonate lenses with a minimum thickness of 3mm	Labelle et al. 1988 [6] Easterbrook 1981b [40] Gregory 1986 [44] North 1973 [50] Capão Filipe et al. 2003 [38] Easterbrook 1981c [41] Easterbrook 1988 [42] Kahle et al. 1993 [28] Knorr & Jonas 1996 [47]

3.5.2 Eyewear in badminton

The findings of the studies relating to eyewear use in badminton are in Table 3. Wearing no eyewear or prescription glasses did not prevent eye injuries and may have increased the severity of any injury experienced. Eyewear compliant with updated ASTM (or similar) standards should be used to decrease injury incidence and prevent serious cases.

Table 3. Summary of the evidence relating to the effectiveness of eyewear (or lack of eyewear) in reducing eye injuries in badminton.

Type of eyewear	Effectiveness	Studies
No eyewear	Injuries occurred that required surgery Penetrating injuries occurred Some injuries occurred that had a permanent impact on the patient’s vision Some injuries occurred that resulted in blindness	Kelly 1987 [46] Yu et al. 2020 [21] Gregory 1986 [44] Fong 1994 [1] Luong et al. 2017 [49] Wang et al. 2020 [55] Jones 1987 [4] Khandelwal et al. 2012 [11] Jao et al. 2017 [10] Rasidin et al. 2022 [52] Kawamata et al. 2022 [45] Li et al. 2021 [48]
Prescription glasses	They did not offer adequate protection Some shattered on impact with a shuttlecock/racket which further complicated any injury that was experienced They may increase the likelihood of a penetrating injury	Kelly 1987 [46] Yu et al. 2020 [21] Gregory 1986 [44] Fong 1994 [1] Tsui et al. 2017 [53]
Eyewear compliant with official standards such as ASTM F803 or ASTM F3164	No injuries were recorded when players were wearing this eyewear Several studies recommend the use of eyewear that meets the ASTM F803/ASTM F3164 standards Several studies recommend the use of polycarbonate lenses	Yu et al. 2020 [21] Fong 1994 [1] Luong et al. 2017 [49] Tsui et al. 2017 [53] Jones 1987 [4] Khandelwal et al. 2012 [11] Jao et al. 2017 [10]

3.5.3 Eyewear in tennis

The findings of the studies relating to eyewear use in tennis are in Table 4. When no eyewear was worn, injuries occurred. Prescription glasses may have a protective effect but it was clear no eye injuries occurred when eyewear compliant with updated ASTM (or similar) standards was used.

Table 4. Summary of the evidence relating to the effectiveness of eyewear (or lack of eyewear) in reducing eye injuries in tennis.

Type of eyewear	Effectiveness	Studies
No eyewear	Injuries occurredif no eyewear was worn Some injuries led to hospitalisation Some injuries required surgery	Gregory 1986 [44] Jones 1987 [4] Doxanas & Soderstrom 1980 [30]
Prescription glasses	One study suggests that they have some protective effect (Vinger & Tolpin, 1978) Another study suggests they can shatter on impact and complicate the injury (Gregory, 1986)	Vinger & Tolpin 1978 [54] Gregory 1986 [44]
Eyewear compliant with official standards such as ASTM F803 or ASTM F3164	No injuries have been reported when players wear this eyewear	Jones 1987 [4]

4. Discussion

The objective of this systematic review was to analyze the effectiveness of protective eyewear use (or lack of eyewear) in reducing the severity and incidence of eye injuries in racket sports. To the authors’ knowledge there is only one other review that has investigated this topic which was conducted over 20 years ago [56]. More data has since been collected and therefore it was appropriate to update the literature.

Twenty nine studies were included, providing enough evidence to investigate eyewear use in squash, racketball and badminton. However, due to a lack of evidence relating to eyewear use in tennis (only four studies provided useful information) it was difficult to make substantiated conclusions for tennis.

4.1 Subgroup analysis

The median percentage of eye injuries that occurred in all the sports included in this review when no eyewear was worn was 93%. This shows that there is significant potential to reduce eye injuries in racket sports if protective eyewear is worn.

4.2 Squash and racketball

Players who do not wear any eyewear (protective or otherwise) sustain eye injuries with potentially serious consequences such as permanent vision loss. Prescription glasses and contact lenses may make injuries more severe. Lensless eye guards are ineffective as when they are struck, the ball deforms allowing it to make contact with the eye, causing injury. Industrial eyewear (made from CR39 plastic) may offer some protection but in some cases have shattered on impact. Conversely, no injuries have been reported when eyewear compliant with updated ASTM (or similar) standards has been worn.

Canada led the way in advocating protective eyewear use when in September 1978 the Canadian National Racquetball Association stated protective eyewear use was compulsory in any tournaments they organized [41]. However, the main type of protective eyewear used at the time was lensless eye guards which were later found to be ineffective and in some cases further complicate injuries as they caused the ball to be compressed and projected into the orbit (for example, Clemett and Fairhurst, 1980 [57] and Easterbrook, 1982 [23]). Therefore, efforts were made to improve the quality of protective eyewear. In 1980, the Eye Safety Committee of the ASTM was formed and in 1983 standards were published by the ASTM (ASTM F803) [33]. Other similar standards were then created around the world such as the Australian AS 4066, Canadian CSA P400, British BS7930–1 and the New Zealand NZS 4066. Then, in 1985 the Eye and Face Protective Equipment Certification Council (EFPECC) was formed to independently oversee the testing of all protective eyewear designed for sporting use [33]. After the creation of the ASTM F803 standard, regulations began to be put in place. In 1983, the United States Rackets Association (USRA at the time but now USAR) made it compulsory to wear closed eye guards in all national competitions [42]. Subsequently, NGBs and regional associations introduced rules relating to protective eyewear use.

In recent times, the standards for protective eyewear have been updated. The ASTM F803 standard was replaced by the ASTM F3164–19 in 2019 to create a standard that was specific to racket sports. In 2021 the ‘International Organization for Standardization’ (ISO) published the ISO 18,527–2 standard called ‘Requirements for eye protectors for squash and eye protectors for racquetball and squash 57’ [58] which was also considered to be applicable to sports that have similar risks and hazards such as tennis and badminton. Also, the ISO 18,527–2 has been used by other standardized bodies as the basis for their own standards for protective eyewear use in racket sports, such as the AS/NZS 18,527.2:2022 published by ‘Standards Australia’ and ‘Standards New Zealand’ [59]. However, the updates in standards have not been accompanied by rule changes. At the time of writing, the World Squash Federation only make protective eyewear compulsory for players in doubles matches or for those under 19 years of age [60]. All major NGBs (US Squash, Australian Squash, Squash Canada) have some rules regarding protective eyewear use in competitive events they organize except England Squash. They strongly recommend protective eyewear but have no specific rules. However, the rules from the other NGBs appear to have had an impact in reducing eye injuries in squash and racketball. It has been found that once rules on protective eyewear use were introduced, the proportion of sports related eye injuries caused by racketball and squash dropped from 73% to 23% [61].

Therefore, although some steps have been taken to reduce eye injury incidence [61], the evidence from this review suggests wearing eyewear compliant with updated ASTM (or similar) standards reduces eye injury incidence and severity and so further action needs to be taken. It is recommended that governing bodies should review the evidence and then make decisions on whether to update their current policies on the use of protective eyewear.

4.3 Badminton

No injuries have been reported when eyewear compliant with updated ASTM (or similar) standards was worn. Not wearing eyewear (protective or otherwise) has no effect in reducing incidence and severity of injury with some patients’ vision being permanently affected. Prescription glasses have no protective effect and may complicate injuries if the lenses shatter on impact. This may cause penetrative injuries.

Compared to the other sports in this review, more recent literature has been published on badminton eye injuries. Pashby [62] stated more injuries were occurring in badminton than in tennis, squash and racketball combined. However, the increasing evidence of injuries has not led to widespread behavioral change unlike in squash. Pashby [62] believed the reason why more injuries were occurring in badminton was the increase in protective eyewear use in both squash and racketball. Despite Pashby’s conclusion, Luong and colleagues [49] reported the majority of Canadian badminton associations have no rules on eyewear compliant with updated ASTM (or similar) standards. Only British Columbia and the Ontario Badminton Association have made it compulsory to wear eyewear meeting ASTM standards, but only for players under 19 years of age [49]. The situation is similar across the world with Badminton England, USA Badminton and Badminton Australia having no rules on protective eyewear use.

As with squash and racketball, governing bodies and key policy decision makers within badminton need to consider the evidence and be open to the possibility of implementing rules and recommendations to reduce eye injury incidence and severity.

4.4 Tennis

Injuries occur when eyewear is not worn. There is debate whether prescription glasses provide any protection, but no injuries have been reported when eyewear compliant with updated ASTM (or similar) standards has been worn.

Compared to the other sports investigated in this review, there is very little research in this area and further investigation is required. To the authors’ knowledge, no NGBs have created laws or recommendations around protective eyewear use. This is likely to be because a tennis ball has a diameter of around 6.25 cm [29] and so due to its relatively large size, it is hard for a tennis ball to enter the eye orbit. This contrasts with the diameter of a squash ball ranging from 3.9–4.3 cm [63], the diameter of a racketball which is around 5.5 cm [63] and the diameter of a shuttlecock which is approximately 1.8 cm [10]. However, tennis balls travel at 177kph, which although is slower than values reported for squash and badminton (225kph and 209kph), it is the same speed as balls in racketball [29]. Therefore, a significant amount of energy needs to be dissipated when a tennis ball hits the eye and this is why some tennis eye injuries can be very serious and require surgery [30].

Therefore, it is recommended that NGBs should examine the evidence and consider recommending the use of protective eyewear when playing tennis. The risks appear to be smaller than the other racket sports included in this review but nonetheless, serious injuries have been reported and wearing eyewear compliant with updated ASTM (or similar) standards would probably have prevented them. Therefore, it is recommended discussions on the use of eyewear take place between key stakeholders within the sport.

4.5 Limitations

There are some limitations that have to be considered when interpreting the findings of this systematic review. Firstly, only 3 databases (PubMed, SportDiscus and Web of Science) were searched and no unpublished literature was included. Therefore, it is possible some relevant papers were not retrieved. Another limitation is caused by the nature of the evidence itself. In all the studies it was very difficult to create an accurate estimation of the population who played the racket sport(s) in the location and time period of the study. This means statistical measures of eye injury incidence were not calculated in each study, making any form of statistical analysis impossible. Another limitation is that all the studies were conducted in professional medical settings. Therefore, many minor injuries that may relate to eyewear use in racket sports will not have been included in this analysis as they did not require medical treatment. However, arguably it is more important to focus prevention efforts on more severe injuries (which will have been included in this review) as they have more serious consequences both for patients and health care providers. Finally, only one investigator carried out the data extraction.

Despite these limitations, the body of evidence in this review is high enough quality to shape practice. Although there are case studies and case series sampled from unclear population sizes, this is the only feasible way data can be collected on this topic. In addition, the protocols that were followed to report, diagnose and treat the injuries in each study were reliable and valid and so provides high quality evidence that can be analyzed.

4.6 Conclusions and recommendations

Eyewear compliant with updated ASTM (or similar) standards reduces eye injury incidence and severity in squash, racketball, badminton and tennis. All other forms of eyewear such as prescription glasses, contact lenses, lensless eye guards and industrial eyewear do not provide adequate protection. Therefore, since eyewear compliant with updated ASTM (or similar) standards provides reliable protection, is a relatively low-cost solution and eye injuries are very costly both to the injured player and health care providers, it is recommended that NGBs strongly consider implementing recommendations or rules around protective eyewear use to reduce eye injury incidence and severity. In squash and racketball, there are existing laws on protective eyewear use for juniors, in doubles matches and in competitions run by governing bodies. In badminton, only a small number of regional associations have laws relating to protective eyewear. Therefore, existing laws could be extended in these sports and in tennis, discussions around the use of eyewear should be held.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

Data sharing is not applicable to this article as no new data were created or analyzed in this study.

Supplementary Material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/00913847.2023.2196934.

Additional information

Funding

The author(s) reported there is no funding associated with the work featured in this article.