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Editor,—A cluster of four cases in 4 months of inadvertent injury of the globe after peribulbar anaesthesia (PBA) administered by both anaesthetists and ophthalmologists has led us to review their risk factors, management, and outcome with respect to the literature.1-5 Despite varying symptoms the common sign of inadvertent injury was vitreous haemorrhage either preoperatively or immediately postoperatively. Time to referral for vitreoretinal opinion ranged from immediate to 48 hours by which time all eyes had extensive vitreous haemorrhage precluding visualisation of the fundus. All injuries required trans pars plana vitrectomy and internal tamponade with resulting visual acuity ranging from 6/9 to HM (Table1).
PBA was first promoted as a safer alternative to retrobulbar anaesthesia (RBA) but a prospective comparative study has not been undertaken.6 The advantages of PBA include reduced incidence of inadvertent penetration of intraconal tissues which can result in brain stem anaesthesia while the disadvantages include inadequate akinesia in up to 50% of cases.1 2 Ocular factors such as increased axial length and technical factors such as inadequately trained personnel are associated with inadvertent injury which can result from administration of the anaesthetic by both ophthalmologists and anaesthetists.1-5 Inadvertent injury produces a variety of symptoms and signs and may even be silent.2-5 Although intraocular injections of anaesthetic agents are not retinotoxic, damage can result from mechanisms such as “jet stream effects” and elevation of the intraocular pressure.3 7 8
Suspicion of an inadvertent injury by the administrator of the anaesthetic must be conveyed to the operating surgeon (if they differ), so that a full assessment can be performed before surgery.2 3 Differentiation between penetrating injuries (only an entry site) and perforating injuries (an entry and an exit site) and classification into one of three categories depending on the clarity of the media and the presence of retinal detachment has management implications.3 Category one patients with an adequate fundal view without retinal detachment may be watched as local haemorrhage may preclude the need for prophylactic laser therapy (cryotherapy in the presence of local haemorrhage has been implicated in the development of proliferative vitreoretino pathy).2-4 We agree with previous reports that trans pars plana vitrectomy in category two (an adequate fundal view with retinal detachment) and category three patients (an inadequate fundal view) is the treatment of choice.2 3 Patient outcome depends on the amount of initial damage to the retina and despite successful retinal reattachment, factors including epiretinal gliosis, optic atrophy and proliferative vitreoretinopathy can result in poor visual acuity.2-5 Adequate training of personnel and a high awareness of potential risk factors1 may help to reduce the incidence of this serious complication of local anaesthesia. Early recognition of an injury and early vitreoretinal opinion to categorise the patients and formulate a management strategy may maximise a patient’s visual outcome.2-5