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

Panretinal photocoagulation (PRP) is tolerated well by most patients u sing topical anaesthesia alone, though there are a significant number of patients who experience pain. Additional local anaesthesia alternat ives for these patients include retrobulbar, peribulbar or subconjunct ival injection. Deep introduction of a sharp needle may rarely cause d amage to orbital structures, whereas no-needle sub-Tenon irrigation of local anaesthetic solution to the posterior Tenon's space theoretical ly avoids these risks. A one-quadrant, inferior-nasal, sub-Tenon deliv ery 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 to pical anaesthesia alone. To assess the efficacy of anaesthesia, patien ts mere asked to score pain, using a visual analogue score chart grade d 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 6-1 0. 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-Ten on 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 d emonstrates significantly better anaesthesia with sub-Tenon irrigation than topical treatment alone (p<0.005, Wilcoxon ranked sign test). If a patient tolerates PRP with simple topical anaesthesia then this is t he method of choice. Topical anaesthesia is non-invasive, though if pa in is experienced, one-quadrant sub-Tenon anaesthesia can provide effe ctive anaesthesia for PRP with the benefit of seeking to avoid the ris ks of sharp needle techniques.