NO-NEEDLE ONE-QUADRANT SUB-TENON ANESTHESIA FOR PANRETINAL PHOTOCOAGULATION

Panretinal photocoagulation (PRP) is tolerated well by most patients using topical anaesthesia alone, though there are a significant number of patients who experience pain. Additional local anaesthesia alternatives for these patients include retrobulbar, peribulbar or subconjunctival injection. Deep introduction of a sharp needle may rarely cause damage to orbital structures, whereas no-needle sub-Tenon irrigation of local anaesthetic solution to the posterior Tenon's space theoretically avoids these risks. A one-quadrant, inferior-nasal, sub-Tenon delivery of 1.5-2 ml plain 2% lignocaine was administered and PRP performed on 12 eyes of 12 patients who were previously intolerant of PRP by topical anaesthesia alone. To assess the efficacy of anaesthesia, patients mere asked to score pain, using a visual analogue score chart graded from 0 to 10. If patients mere unable to see the chart, or read the accompanying text, a verbal explanation and description of the scoring chart was performed. Where PRP was performed with topical amethocaine 1% alone, pain scores were graded as median 8, mean 8.5 and range 6-10. The administration of sub-Tenon anaesthesia was well tolerated with a median pain score of 1.5, mean 1.9 and range 0-5. PRP after sub-Tenon administration was successfully completed in 11 of the 12 patients with a median pain score of 1.5, mean 1.8 and range of 0-9. The range was wide due to one patient with a high pain score who was intolerant of PRP in spite of the sub-Tenon delivery. Assessment of pain scores demonstrates significantly better anaesthesia with sub-Tenon irrigation than topical treatment alone (p<0.005, Wilcoxon ranked sign test). Ifa patient tolerates PRP with simple topical anaesthesia then this is the method of choice. Topical anaesthesia is non-invasive, though if pain is experienced, one-quadrant sub-Tenon anaesthesia can provide effective anaesthesia for PRP with the benefit of seeking to avoid the risks of sharp needle techniques.