Transient blindness after subconjunctival anaesthesia for diode laser cyclophotocoagulation of advanced glaucoma

Background: Retro- and parabulbar anaesthesia can be associated with severe sight-threatening and life-threatening complications and may compromise optic nerve function, especially in eyes with advanced optic neuropathy. Subconjunctival anaesthesia usually does not influence optic nerve function. We report on two patients who developed transient amaurosis after subconjunctival anaesthesia. Patients: In two patients (75 and 77 years old) with advanced refractory glaucoma a diode laser cyclophotocoagulation was performed to lower the increased IOP. For local anaesthesia, 2ml of 2% mepivacaine was placed beneath the conjunctiva. The needle was placed at least 6 mm from the limbus to avoid bleeding at the injection site near the limbus. After 10 minutes, both patients observed a decrease of their vision of the treated eyes. A few minutes later, an amaurosis of the treated eyes was found in both patients, which was fully reversible after 2 to 3 hours. At fundus examination, no vessel occlusion was seen. Conclusions: Subconjunctival anaesthesia may cause transient blindness in patients with advanced optic neuropathy. The incidence of this side effect seems very low.