Drones’ side effect: facial and ocular trauma caused by an aerial drone

Abstract

An adult man was struck in the face by his own aerial drone. The propellers hit the upper face region leading to forehead and eyelid lacerations, a partial scleral laceration, conjunctival laceration, hyphaema, traumatic iritis and forward displacement of one haptic of the intraocular lens from a previous cataract surgery. In the last decade, drone use has significantly increased and drone-related injuries have become an emerging cause of trauma. Our case raises awareness of the risks and highlights the need for improvement in regulation of drone use.

Background

Invented in the early 1900s for the army, unmanned aerial vehicles or drones are now widely used for civil as well as commercial, scientific, agricultural and recreational purposes. Increase in use by untrained ‘pilots’ has led to an increased rate of drone-related accidents and injuries.¹

There have been studies into the simulated effects of impact with a drone, but only two cases of trauma caused by a drone have been published^2–4 We describe a case where an adult was referred to our emergency department after being struck in the face by his own drone. He suffered several eyelid and skin lacerations caused by the propellers and a closed globe ocular trauma resulting in dramatic reduction in his vision.

This case highlights an emerging cause of trauma and highlights the potential risks of drones use. We briefly review the emergency management, in case of ocular trauma. We hope that our case report will raise awareness and help regulate its use.

Case presentation

A 60-year-old man racing drone pilot was referred to our emergency department to rule out a left globe rupture, after his own four-propeller racing drone struck his face. Our patient was in sole control of the drone at the time of the accident, while performing a landing manoeuvre. He did not respect the safety distances and lost control of the drone as it approached him, without being able to avoid the impact.

His ocular history included bilateral cataract surgery with in the bag implantation of a Stabibag intraocular lens (IOLTECH laboratories (now part of Carl Zeiss Meditec). He had no retinal pathology and his vision was 6/6 bilaterally.

Our patient suffered forehead skin lacerations (figure 1) and left upper and lower eyelid lacerations (figures 2 and 3) caused by the drone’s propellers. In the primary care emergency department, a brain and orbital CT scan showed no fractures. A plastic shield was placed on the left eye and the patient was transferred to our tertiary centre for a comprehensive ophthalmic assessment.

Figure 1.

Forehead skin laceration caused by the drone’s propeller.

Figure 2.

Left eye eyelid laceration due to drone’s propeller.

Figure 3.

Left eye eyelid laceration, cornea remains intact. The red dotted line surrounds the hyphaema.

At that time, slit lamp biomicroscopic examination revealed an anterior chamber hyphaema (figure 3) and severe intraocular inflammation as well as an anterior dislocation of the capsular bag with the inferior temporal haptics. This anterior displacement caused a corectopia (figure 4).

Figure 4.

Left eye corectopia. The edges of the pupil are marked by the blue dotted line.

The best corrected visual acuity in the left eye was hand movements. A large subconjunctival haemorrhage and conjunctival laceration led us to suspect a penetrating globe injury. We performed a surgical exploration under general anaesthesia to exclude or repair an ocular globe laceration. We found a partial thickness scleral laceration which required suturing and closed the conjunctival lacerations with 7–0 absorbable braided sutures. The eyelid skin was sutured with interrupted 6–0 nylon sutures.

An ocular ultrasound B-scan excluded vitreous haemorrhage, retinal detachment or choroidal haemorrhage. As per protocol, we gave antibiotic prophylaxis with oral moxifloxacin 400 mg one time a day for 5 days. Postoperatively, topical anti-inflammatory and antibiotic drops (dexamethasone, neomycin sulfate and polymyxin B sulfate) were instilled six times daily. The intraocular pressure remained normal.

During a postoperative assessment 4 months later, with optical coherence tomography imaging, it was noted that the macula was significantly damaged with outer retinal atrophy (figure 5). The foveal thickness had decreased from 245 µm to 143 µm. Visual acuity improved to 6/30 without an increase in intraocular pressure. We managed his case conservatively due to poor visual prognosis limited by the macular changes, additionally the patient preferred not to proceed with an intraocular lens exchange.

Figure 5.

Outer retinal atrophy imaged by optic coherence tomography.

Discussion

We report the first adult case of drone-related ocular trauma, the only other published case concerns a child.⁴ Our patient who is a seasoned racing drone pilot admitted that his mistake was to not respect the well-known safety distances for take-off and landing manoeuvres.

The mechanisms of injury are multifaceted including: impact from the falling drone, impact from the flying drone at different speeds and laceration due to the propellers. Speed, height and drone mass influence the severity of the injuries.² Drone impacts are significant enough to fracture human bones including the skull.^{2 3}

Consequently, ocular injuries can involve every structure in the eye. First, the high velocity impact can fracture orbital bones. If suspected, brain and orbital CT scan is the gold standard to evaluate bones and may give some insight into the extent of ocular involvement. In case of fracture, we usually prefer to delay repair unless its in a child or the fracture involves extraocular muscle entrapment.

An ophthalmic examination is always mandatory. Skin lacerations are often obvious. Attention must be paid to lesions including the medial canthus, given that they can involve the lacrimal drainage system and need microsurgical repair urgently. Full thickness eyelid defects are also important to repair with appropriate exploration and apposition to reduce long-term morbidity due to scarring and poor lid closure. Additionally, globe rupture must always be suspected in ocular drone-related trauma.

Corneal lacerations are usually obvious, which did not occur in this case. Occult globe rupture is much more difficult to diagnose.⁵ Indirect signs include extensive chemosis or extensive subconjunctival haemorrhage, relative hypotony and vitreous haemorrhage. Orbital CT scan can show globe deformation but a dilated ophthalmic examination is mandatory. Scleral exploration after 360° peritomy is needed to rule out globe rupture if suspected. Until ocular perforation is excluded, we protect the globe from external pressure and reduce chances of any Valsalva manoeuvres. Once ocular globe rupture is excluded, one must look for ocular contusion with possible hyphaema, angle recession, lens dislocation, vitreous haemorrhage, retinal detachment and retinal oedema. In some cases, commotio retinae (a bruised retina) can lead to disruption and atrophy of the outer retina leading to a severe visual loss.^{6 7} Our case illustrates this unfortunate complication with macular atrophy following the resolution of the commotio retinae. Documentation of a relative afferent pupillary defect and any change in its status are recommended every 4 hours or sooner depending on clinical status. Antibiotic prophylaxis is advised since endophthalmitis is a devastating complication.

In case of ocular trauma, we recommend a complete ophthalmological assessment and long-term follow-up depending on clinical findings. We give retinal detachment warnings and advise annual intraocular pressure checks by an optician.

Even for a trained pilot, piloting a drone is not without risk. It is therefore important to scrupulously respect safety measures. It may even be advisable to undergo training or even obtain a licence before using a unmanned aerial vehicle (UAV). Safety equipment such as a helmet or safety goggles could be recommended to pilots and persons in the vicinity of UAVs.

Patient’s perspective.

I am terribly angry, because I am actually an experienced drone user. I frequently flew my drone and I knew the safety rules. This one time I did not respect the rules and the consequences were quite dramatic for me. Fortunately I did not injure anyone else. I do not want my accident to cause a demonization of drones, but we must remember that we need to respect the safety rules. When you follow these rules, accidents are less likely to happen.

Learning points.

• We reported the first drone-related ocular trauma in an adult. Increased recreational drone use has led to an emerging cause of ocular trauma. Emergency services and regulatory bodies must be made aware of the potential danger of drone use.

• We recommend to improve regulation of drone use to reduce the risk of injury to user or surrounding public. We encourage protective eyewear and improvement of drone design to promote safety. Even experienced drivers, such as our patient, can be involved in an accident if they do not follow the safety instructions. Obtaining a licence or undergoing training before driving an unmanned aerial vehicle could be a solution for avoiding accidents.

• Emergency care providers should remember that drones can cause bone fracture, globe rupture and globe contusion. Globe rupture must always be ruled out by a careful ophthalmic examination. In cases of ocular trauma, follow-up is mandatory to exclude long-term complications such as intraocular inflammation, retinal detachment or glaucoma.