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Editor,—Glasses are perceived to be a protective eye shield; however, when lenses shatter severe ocular injuries may result. Several reports discuss the relation of spectacle design to their safety, both the lens and the frame contributing spectacle stability.1-4 A trend for thin or absent frames may place some patients at increased risk of serious ocular injury. We present the case of a car driver who sustained a perforated globe when glass frameless spectacles fractured during a low impact collision.
A 37 year old woman wearing, glass, frameless spectacles (Rodenstock R244C), collided with a lamp-post at around 15 mph (24 km/h). She was driving a small hatchback car and the impact was sufficient to damage the bonnet and windscreen. The car was not fitted with air bags but the driver and passenger were wearing three point seat belts. The driver's head fell forwards hitting the steering wheel and fracturing her spectacles (Fig 1). The force was not sufficient to bruise her face. A shard from the spectacles lacerated the patient's left eye.
When the patient was seen in casualty a 14 mm, trans-cornea laceration was noted, which extended into sclera (Fig 2). The cut was clean and linear with no loss of corneal tissue. A total hyphaema was present with a brisk haemorrhage from the wound. Further examination at surgery revealed a clean laceration with loss of the crystalline lens and two thirds of the inferior iris; no intraocular foreign body was found. Primary repair was undertaken, prolapsed iris and vitreous were removed. The wound was closed with 10/0 nylon to the cornea and 6/0 Vicryl to the sclera. The patient's postoperative recovery was covered with systemic antibiotics, topical steroids, and cycloplegics.
Following surgery the patient regained hand movement vision. Ultrasonography initially showed choroidal detachment and vitreous haemorrhage. The choroidal effusions settled over 10 days. Postoperative pressure spikes were controlled with Iopidine (apraclonidine 0.1% twice daily), timolol (0.25% twice daily), Alphagan (brimonidine, 2% twice daily) drops, and oral acetazolamide (250 mg four times daily).
At 2 weeks after injury a three port pars planar vitrectomy was performed to clear the visual axis of haemorrhage, and the retina was found to be relatively undamaged. Following this procedure the IOP was controlled with Iopidine (0.1% twice daily) and timolol (0.25% twice daily) and the patient recovered to counting fingers vision which was maintained at 6 months.
The issue of ocular damage from spectacle wear has been highlighted by the widespread introduction of airbags as a safety feature in modern cars.5 The incidence of such injuries is difficult to estimate; however, there are at least 140 reported in the literature.1 Myopic patients are three times more likely to suffer globe perforation than hypermetropes2 owing to mechanically weaker spectacle lenses. The male to female ratio is 7:1 and one third of these eyes become legally blind.6
Lenses made from polycarbonates are less likely to shatter than glass lenses3 4; however, even with these lenses spectacle wear presents an additional risk for blunt and penetrating injury during car accidents.5 Keeney et al showed that the tendency of a lens to shatter is defined by its stored elastic energy and its tendency to oscillate after the impact, both higher in glass lenses,7 and reduced by compressing the lens with a frame.8 Lens breakage may be reduced by inserting a 0.1 mm posterior lip in plastic frames or a plastic liner to metal frames. There are several case reports of penetrating ocular injuries either from the spectacle frame or from shattered glass in patients travelling a modest speeds.9 10 Our case demonstrates the effect of a low speed collision on frameless spectacles with glass lenses, dramatically increasing the likelihood of ocular injury from airbag activation or relatively minor collisions. Although polycarbonates are often used in the manufacture of many frameless spectacles their mechanical strength has not been reported in the literature. This case raises doubts about the safety of these spectacles, especially when made with glass lenses.