Double masked randomised controlled trial to assess the effectiveness of paracetamol in reducing pain in panretinal photocoagulation

Aim: To assess the effectiveness of pre-emptive analgesia with paracetamol in reducing pain associated with panretinal photocoagulation ( PRP) in a prospective, double masked, randomised controlled trial. Method: 60 patients undergoing PRP for the first time were enrolled and randomised to paracetamol or placebo, taken for 2 days starting 24 hours before the laser treatment. The laser treatment was performed following a standardised protocol. Pain during and after treatment was assessed using the McGill pain questionnaire ( MPQ) and visual analogue scales ( VAS). Results: The statistical analysis looked for differences between the two study groups immediately after the laser surgery and 24 hours later. There was no statistically significant difference in the primary outcome measure of perception of pain during and 24 hours after PRP, between the paracetamol and placebo group. However, none of the patients in the paracetamol group reported increased total pain at 24 hours, whereas six patients in the placebo group reported increased pain; this difference ( 21%) was significant to p = 0.01. Conclusions: Pre-emptive analgesia with paracetamol did not significantly reduce pain associated with PRP. This study has described for the first time the type of pain associated with PRP, which is perceived mainly as a discomfort. The main attributes of the pain that patients described, were sharp, flashing, tiring, intense, piercing, intermittent, and brief.