Eye Injuries Caused by Wooden Projectiles in Finland

Introduction Eye injuries can cause decreased vision or even blindness, and predispose to future complications. Wood as an independent cause of eye injuries has infrequently been the focus of the studies. The aim of this study is to report the current population-based epidemiology, treatment, use of resources and outcomes of eye injuries caused by sticks, branches, and other wooden projectiles in Finland. Methods The study included all patients injured by wooden projectiles with ocular or orbital traumas over a 1-y period. Patients were treated at the Helsinki University eye hospital, which covers a population of 1.5 million. The follow-up time was 3 mo. Results Wooden projectiles caused 67 eye injuries and compromised 6% of all eye traumas during 1 y. Of the patients, males predominated (76%) and 22% were children under 17 y. Injury was most likely in spring (36%) and in males aged 51 to 67 y. The most common activity to cause injury was playing (27%), but in relation to time spent in each activity, the highest risk for eye injury was in gardening. Diagnoses were mild superficial trauma (54%), blunt ocular trauma (37%), eyelid wound (4%), orbital fracture (3%), and open globe trauma (1%). Permanent disability was estimated for 10% and a need for lifelong follow-up was estimated for 37%. Eleven patients needed major surgeries. Conclusions Wooden projectiles often cause serious eye injuries, permanent disability, and a need for lifelong follow-up. Caution is required to protect the eyes when playing with sticks and during gardening, forest work, and woodwork.


Introduction
Wood as an independent cause of eye injury has rarely been the sole focus of studies.5][6] Among geriatric patients, wood strike was the most common reason for penetrating eye trauma in Turkey. 7][10] As an organic material, untreated wood entails a risk for serious infections.1][12] On the other hand, in a few larger studies, no particular type of organism predominated and no mycobacteria or fungi were found. 8,9he purpose of this study was to provide an overview of the types of eye injuries wood causes.

Methods
The study includes all eye trauma patients injured by wooden items, for example, sticks and branches, who were taken into care at the emergency clinic of Helsinki University eye hospital (HUEH) over a 1-y period from May 1, 2011, to April 30, 2012.The HUEH is the sole tertiary and secondary eye care hospital in the area, covering a population base of 1.5 million.Patients injured by wooden dust, cosmetic wooden items, and matchsticks were excluded from the study.The study protocol was approved by the local ethics committee of the Helsinki-Uusimaa hospital district and followed the tenets of the Declaration of Helsinki.
Patients were first prospectively identified in the emergency clinic and requested to fill out the questionnaire.Secondly, to obtain full coverage of the data the hospital records were accessed and ICD-10 diagnoses indicating eye injury were searched from hospital records to find missed patients.The case history of all patients was examined and the accuracy of the injury details were confirmed.From all patients (n=1151), patients injured by wooden projectiles were selected for this substudy.
A patient questionnaire inquired about the circumstances and causes of the accident, use of protective eyewear, influence of alcohol, and whether the injury was intentional.Informed consent was obtained from patients or their caregivers.In the absence of the questionnaire (n=28), the same information was gathered from the hospital records.Additional information, including the involved eye, age, sex, possible amblyopia, detailed clinical findings structurized by anatomic site and finding type, diagnoses, treatments, use of resources, sick leave days, and activity restrictions were recorded for all patients from hospital records.The follow-up time was 3 mo.The record from the last visit included the final visual acuity (VA), intraocular pressure (IOP), and significant symptoms and clinical findings.
Severity of the eye trauma was evaluated by estimating the need for lifelong follow-up, by performed surgery and estimated future surgery, and by permanent disability due to abnormal VA (<0.5 Snellen equivalent) or other functional symptoms.
Eye traumas were divided into 5 primary diagnosis groups: "blunt ocular trauma," "wound" referring to wound in eyelid or periorbital area, "orbital fracture," "open globe trauma" or group "other" referring to mild superficial trauma in the eye or periorbital area.Clinically, the most significant ocular trauma or the one needing most health care resources was chosen as the primary diagnosis.Possible secondary and tertiary diagnoses were recorded.In cases of binocular eye injury, the more seriously injured eye was selected.The energy of the trauma was evaluated as high-energy, if tools or falling was involved.
Resource use was estimated by the number of outpatient visits, duration of hospitalization and medication, number of operations performed, and need for sick leave or activity restriction.4][15][16] Where averages were determined, results were noted as mean±SD (range).
Activity during the accident was categorized into gardening, forest work, play, outdoor recreation, woodwork, or in different sports.Woodwork referred to working with wood as a hobby or at work.Forest work was chosen when the trauma took place during silviculture work, eg, harvesting wood and planting.Data on alcohol use and relation to work or assault was collected.
The incidence rates of eye injuries in each activity were calculated by dividing the number of accidents by the total population time spent in each activity in the HUEH area.The time spent in each activity was obtained from a Finnish time use study on forest activities, 17 and from a Finnish time use survey from Statistical Finland PX-web statistical database.Confidence intervals of 95% were calculated by exact method and used for statistical analysis of gardening, forest work, woodwork, outdoor recreation, cycling, skiing and orienteering.Data were available for people over 10 y of age.
Because some activities are seasonal in Finland, the year was divided into 4 seasons: spring (March, April, May), summer (June, July August), autumn (September, October, November) and winter (December, January, February).Epidemiological data were analyzed, distributions presented, and percentages calculated from the reported results.

Results
Wooden projectiles caused 67 eye traumas, which is 6% of all eye traumas treated at HUEH in a 1-y period.Of the patients, 76% (n=51) were males and 22% (n=15) were children under the age of 17 y.The incidence was 4.4 /100,000 population. 18An eye injury was most likely in males aged between 51 and 67 y (n=24) (Figure 1).Two patients were lost to follow-up.
The injury was equally common in the left and right eye.No binocular traumas or traumas in an amblyopic eye were identified.More injuries occurred during spring (36%) and autumn (27%) (Figure 1).Accidents took place at home (55%, 93% outside the house), at outdoor sites (12%), at school or day care (10%) and at work sites (8%).Data were not available for 16 patients.
There were no known intentional traumas.Alcohol was involved in 3 injuries of males aged 25-26 y.Protective eyewear was used by 1 patient while working with a table saw.
While gardening, an 87-y-old male fell and was diagnosed with open globe trauma and orbital fracture.Eventually, the eye was eviscerated.Other gardening traumas were caused by a hit from a branch.
In forest work, 3 patients were using an axe, 1 a billhook, and 1 a saw.In outdoor recreation, 1 trauma was caused by stumbling in the woods and others were hits from branches.During the woodwork working with table or circular saw (n=3), axe (n=1), poking a window tab (n=1), and building a fence for horses (n=1) caused eye injuries.In sport, injuries were caused by a crash on a bike and in orienteering and skiing by a hit from a branch.
When comparing the number of eye traumas in relation to time used for activity, the risk was highest in gardening, followed by forest work and woodwork (Table 2).
Major surgeries were needed for 10 patients (15%).One patient, probably in need of orbital surgery, was lost to follow-up.High energy was involved in 4 cases.Five patients were predicted to need surgery in the future.All injuries involved tools or falling.
The number of outpatient visits was 167 (2.5±2.4

THREE-MONTH FOLLOW-UP, PERMANENT DISABILITY, NEED FOR LIFELONG FOLLOW-UP
VA was lowered (0.5 Snellen equivalent or less) in 4 patients.Three months after the accident, 2 patients were medicated for elevated IOP.Permanent disability was predicted for 7 patients (10%) because of lowered VA (n=3) due to retinal ablation, cataract, and subluxation of artificial lens, diplopia (n=2), evisceration (n=1), and glare due to mydriasis (n=1).Activities were various.High energy was involved in 5 cases.Tools were used in 2 cases, in forest work and woodwork.No children under the age of 17 y had a permanent disability (Table 1).
The need for lifelong follow-up was predicted for 25 patients (37%) because of elevated glaucoma risk (n=24) and evisceration (n=1).The most common activities were playing, gardening, forest work, and woodwork.High energy was involved in 10 cases.Tools were used in 7 cases, in forest work and woodwork-caused injuries.Six patients were children under the age of 17 y.

Discussion
This study presents a wide variation of eye injuries caused by wooden projectiles.We present a comprehensive population-based longitudinal study over a 1-y period from southern Finland.In this study, we analyzed the outcome of wooden projectile-caused eye injuries in relation to cause in urban and rural areas of southern Finland.
Interestingly, we found that spring was the most common season for wooden projectile eye injuries.Longer daylight in spring in Finland increases the possibility and enthusiasm for outdoor activities and also increases the time spent in gardens.
In our study, an eye injury was most common in males aged 51 to 64 y.Patients were older than in previous studies. 8,9In Finland, older men seem to be in the greatest danger; they may be more active participants in forest work and gardening.
Playing, gardening, and forest work were the most common activities.In previous study forest work, assault and falling were the most common activities causing intraorbital wooden foreign bodies. 9Compared with our study, there were no assaults, but falling was involved in 4 cases.
In relation to time spent in each activity, gardening, forest work, and woodwork were estimated to include the biggest risk for eye injuries.The use of tools possibly explains the increased risk in woodwork and in forest work.In gardening, only 1 patient used a tool (wood chipper) and another fell.The short working distance to branches may increase the risk for eye injuries.Also, the use of protective eyewear is not routine.Since comparable data for statistical analysis was available for people over 10 y of age and 12 out of 18 patients injured during playing were younger than 10 y, playing was not analyzed.
Permanent disability and need for lifelong follow-up were caused by various activities, but not by playing.The need for lifelong follow-up was not related to high-energy traumas only and also involved children.In 2 cases of severe blunt ocular traumas, the activity could not be defined.
A special interest in previous studies has been in intraorbital wooden foreign bodies.][10] A challenge in wood-induced eye traumas is the difficulty in identifying wood in radiological imaging.9][20][21][22] Also, in our study, the radiological finding was reported as "air in intraorbital space," but since wood was suspected the report was corrected.
In our study, only 1 case of keratitis was diagnosed.Several reports of infections caused by wooden materials exist. 10In many cases, the diagnosis was delayed, with the wooden intraorbital or intraocular foreign body identified only after infection. 8,9,11,12However, the incidence of wood-associated orbital or ocular infections or keratitis has not been reported.According to our study, bacterial infections are rare.
Playing is essential for children and playing with sticks is ubiquitous.Playing should not be restricted excessively, but care should be taken when playing with sticks.Fortunately, playing with sticks did not cause any permanent disabilities.] Contrary to expectation, despite the use of protective eyewear, 1 eye injury took place while working with a table saw.The use of eye protection would likely have prevented or diminished eye injuries in woodwork and forest work, activities in which tools are commonly used.In addition, some accidents occurred unexpectedly in activities where eye protection is not generally an issue.More attention should thus be focused on eye injuries when working with tools or in forestry.Hospitalization, outpatient visits, and medication induce costs for society as direct health care costs.Indirect costs such as loss of income due to sick-leave, home care, and travel costs remains the burden of the individual.Preventing eye morbidity, the economic burden used for eye injury treatment could be aimed for other purposes.Further studies are needed to estimate the real costs of eye injuries.

Limitations
A few limitations are noteworthy.Firstly, the number of patients is relatively small for statistical analysis.Secondly, the short follow-up may affect the evaluation of permanent disability.A longer follow-up would likely have a positive impact since VA may improve after treatment and diplopia may slightly diminish over time. 25In our study, diplopia in 1 patient may decrease over time and operating traumatic cataract probably improves VA.However, obvious disabilities, such as eviscerated eye and glare due to traumatic dilatated pupil can be seen in the 3-mo follow-up.

Conclusions
Our study shows that wooden projectiles cause various eye injuries in a wide range of circumstances, resulting in permanent disability and need for lifelong follow-up for many patients, including children.Most of these injuries are preventable and more attention should be directed to use of eye protection, especially during gardening, forest work, and woodwork.Children should be guided in playing safely with sticks.

Figure 1 .
Figure 1.Age and seasonal variation of patients injured by wooden projectiles.

Table 1 .
Primary diagnoses, permanent disability, and need for lifelong follow-up caused by wooden projectiles in relation to activity.Eleven patients had significant secondary diagnoses , blunt ocular trauma; OGT, open globe trauma; other, mild superficial trauma in the eye or periorbital area.aPercentage calculated from the total number of eye injuries (n=67).
BOTb Percentage calculated from the number of activities.

Table 2 .
Risk for eye injury caused by wooden projectiles in different activities in relation to time spent in each activity.The time period was 1 y a Per 10,000,000.b Included 1 patient.