Open Globe Injury related to Road Traffic Accident: a Retrospective Study

Background To evaluate epidemiology, clinical characteristics and outcomes of patients who sustained road traffic-related open globe injury (OGI) Methods Medical records of all road traffic-related OGI patients who were admitted to the hospital from January 2006 to December 2016 were retrospectively reviewed. Data including age, gender, vehicle type, initial ocular presentation, and final visual outcome were extracted.

effective safety education and encouraging regular adherence to road safety behaviors are challenging issues that need more action.

Background
Open globe injury (OGI), defined as a full-thickness laceration of the eye wall, is one of the main conditions leading to an acquired visual disability and a subsequent decline in quality of life [1]. Previous studies from New Zealand and Singapore estimated the annual incidence of OGI to be 2.8 and 3.7 per 100,000 population [2,3]. There are several etiologies of OGI which have been reported with different characteristics [4][5][6]. Among these, road traffic-related OGI has been consistently described as one of a common condition needed for more preventive actions [7][8][9][10][11].
As there is limited data, this study aimed to assess the demographics, ophthalmic clinical characteristics, and outcomes of severe open globe injuries related to road traffic accidents in a tertiary referral center. The findings may contribute useful data in establishing appropriate health care education for road traffic-related OGI.

Materials and Methods
This retrospective study was performed at Chiang Mai University Hospital, a tertiary referral center in Northern Thailand and conducted in accordance with the Declaration of Helsinki. The protocol was considered and approved by the Research and Ethics Committee, Faculty of Medicine, Chiang Mai University.
The medical records of OGI patients who were admitted from January 2006 to December 2016 were evaluated. Then, the records of injury related to road traffic 4 accidents were identified and reviewed in detail. The collected data included patients' demographics comprising age, gender, laterality, and mechanism of injury.
Ocular features at initial examination including visual acuity (VA), zone and location of injury, wound length, presence of relative afferent pupillary defect (RAPD), anterior and posterior segment abnormalities, presence of endophthalmitis, and associated adnexal injury were noted. Zone of injury was classified according to ocular trauma classification into injury limited to cornea and corneoscleral limbus (Zone I), injury at anterior five mm of sclera (Zone II), and injury that extended more than five mm from the limbus into posterior sclera (Zone III) [17]. An ocular trauma score was calculated from the initial VA, and presence of the following features: globe rupture, endophthalmitis, perforating injury, retinal detachment, and RAPD [18]. The mechanisms of injury were divided by the Birmingham Eye Trauma Terminology System (BETT) into 4 types: globe rupture (referred to eye injury by blunt force), penetration and perforation (referred to eye injury by sharp force), and intraocular foreign body (IOFB) [19]. Ophthalmic management and final VA at last follow-up were evaluated. The improvement or worsening of one or more Snellen VA line at the final compared to presenting visit was evaluated.

Statistical Analyses
Patients' demographics were presented by descriptive analysis.   Table 1.

Discussion
This study found that automobiles were the main vehicle and being a teenager was the risky group for the occurrence of road traffic-related OGI in Northern Thailand.
Penetration by pieces of glass and being hit by part of vehicle were the most frequent associated causative mechanisms. The presence of RAPD and retinal detachment were found to be significant predictors at the initial examination for poor final visual outcome.
The impact of road traffic accidents has been evaluated in several hospitalized eye trauma studies. In Taiwan, Lee et al. demonstrated that the main cause for both principal (20.4%) and secondary diagnosis (47.2%) of admitted eye trauma was traffic accident [7]. In China, Qi et al. pointed out that almost a quarter of hospitalized eye injury (24.2%) occurred from vehicle-related accidents [8].
Nevertheless, when considering the overall incidence of road traffic-related OGI which attained a poorer visual prognosis compared to closed globe injury, the variation in incidence according to countries has been published [9]. In high-income countries, a low incidence of road traffic accidents has been shown which included a study by Li  from US [3,14,15,20,21]. In contrary, a much higher incidence has been reported in a study by Madhusudhan et al. (17.6%) from Malaysia and, accordingly, in this study (9.4%) which were both characterized as middle-income countries [12]. With a relatively high incidence of road traffic-related eye injuries in this region, it is essential to have more actions from the government and community to make the road safer. However, to establish effective enforcement of a road safety system, it is reasonable to properly define the vulnerable risk groups and investigate related consequences following eye injury.
Considering about gender, the result of this study is consistent with other OGI publications, either investigated for overall causes or only for traffic-related injury, which found that male was a major proportion of patients than female, even though varying in ratio [13,15,16,20,22]. This may refer to differences in physical activities between genders. Therefore, public awareness for road safety legislation should be promoted to better understanding among the population, particularly males. Apart from gender, specific age range has been observed to differ between 8 causes of OGI. In fall down-related OGI, the peak incidence has been described in young children and elderly, while patients between 30 to 40 years were at increased risk for occupational-related OGI [3,4,16,23]. Nevertheless, in road traffic-related OGI, the disparities in age range have been demonstrated. A study in US by Orr et al. presented that nearly half of cases (48%) were young patients between 20 to 40 years whereas a study in Japan by Okamoto et al. found that road traffic injury comprised a more proportion of elderly patients with a mean age of 50 years [20,22]. This study, similar to Zhang et al., demonstrated that the highest incidence occurred in young patients between 20 to 39 years which represented teenagers and/or early working groups [10]. This finding is in line with a previous report in Thailand which showed that the most commonly admitted road traffic injured age group was 15 to 30 years old [24]. The less experienced in vehicle-related performance and an easily distracted nature might possibly explain the high incidence of injury in this age range. Then, strategies to encourage the use of safety equipment and follow the safety instructions involving vehicle transportation should be emphasized.
Types of vehicle is another factor that should be accounted for. A study by Orr et al. reported that nearly all cases (96%) were injured by automobiles and the minority were (4%) injured by motorcycles [20]. Okamoto et al noted that the two most frequent injuries were related to car driving (36%) and bicycle riding (14%), while the minority were related to motorcycle riding (7%) [22]. However, this study revealed that the proportion of transportation modes varied by age range.
Motorcycles were the most prevalent in the young while the automobiles were the most frequent in adult and elderly. Regular inspection of safety behaviors during riding/driving including seat belt using, helmet wearing, speed limitation, and non-alcohol or non-mobile phone might benefit for injury prevention across all age groups.
About the mechanism of injury, there were pieces of evidence that globe rupture was the most prevalent type (60 to 64%) in road traffic-related OGI [20,22]. This study noted that a similar proportion of patients sustained injuries from globe rupture and penetration (47 versus 45%). This may refer to the nature of road traffic accidents with a higher chance to obtain diffuse ocular damages by both blunt forces, including hit by vehicle parts or road-related construction, and sharp penetration by objects such as glass. On the contrary, most work-related OGI studies have shown that penetration was the most common mechanism [4,23]. The high proportion of ruptures may partly explain a low visual potential. In this study, even though VA was significantly improved when comparing final to initial visits, 46% of the patients achieved final vision worse than 20/200. Consequently, aiming for prevention combined with prompt treatment should be an effective way to reduce severe visual impairment from road traffic-relate OGI.
This study had some limitations due to its retrospective design. As such, detailed information regarding patient and injury severity may under or overestimated.
Furthermore, as this is a hospital-based study, it might not represent the minor injured population. However, the results point out several aspects of road traffic OGI characteristics in a middle-income country that should be of concern.

Availability of Data and Materials
The datasets used and/or analyzed in this study are available from the corresponding author on reasonable request.  Distribution of Vehicle Modes Involving in Injury by Age Groups