CONJUNCTIVAL CHANGES AFTER SUBCONJUNCTIVAL LIGNOCAINE

Subconjunctival injection of 2% lignocaine at the 12 o'clock position was used as the local anaesthetic in 19 eyes undergoing a primary trabeculectomy for open angle glaucoma. The appearance of the bleb and mean post-operative intraocular pressure (IOP) were compared with those in 29 eyes with the same diagnosis undergoing trabeculectomy under general anaesthesia by the same surgeons over the same time period. The two groups of eyes were similar with regard to treatment with beta blockers (p>0.1), miotics (p>0.25), sympathomimetics (p>0.25), carbonic anhydrase inhibitors (p>0.5), or no treatment (p>0.25). Seventy-seven per cent of the local anaesthetic group and 25% of the general anaesthetic group developed avascular, thin-walled drainage blebs (p<0.001). The mean post-operative IOP was significantly lower in the group receiving local anaesthetic (p<0.001). The reasons for and significance of these observations are discussed, and the merits and disadvantages of thin-walled blebs are evaluated.