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 op tic nerve function, especially in eyes with advanced optic neuropathy. Subc onjunctival anaesthesia usually does not influence optic nerve function. We report on two patients who developed transient amaurosis after subconjunct ival anaesthesia. Patients: In two patients (75 and 77 years old) with advanced refractory gl aucoma a diode laser cyclophotocoagulation was performed to lower the incre ased IOP. For local anaesthesia, 2ml of 2% mepivacaine was placed beneath t he conjunctiva. The needle was placed at least 6 mm from the limbus to avoi d bleeding at the injection site near the limbus. After 10 minutes, both pa tients observed a decrease of their vision of the treated eyes. A few minut es later, an amaurosis of the treated eyes was found in both patients, whic h was fully reversible after 2 to 3 hours. At fundus examination, no vessel occlusion was seen. Conclusions: Subconjunctival anaesthesia may cause transient blindness in p atients with advanced optic neuropathy. The incidence of this side effect s eems very low.