Using the laser flare-cell meter (LFMC), we have previously determined the intensity and pattern of post-ALT ocular inflammation. Inflammation peak occurs 48 hours after ALT and clinically relevant inflammation is seen in 100% of pigmentary glaucomas (PIG), 75% of pseudoexfoliative glaucomas (PEXG) but only in 25% of primary open angle glaucomas (POAG). We also showed that topical diclofenac reduced inflammation in all 17 treated patients. Prostaglandins are thought to play a major role in ALT-inflammation and it is therefore logical to assume that NSAID are effective in that situation and will probably advantageously replace corticosteroids. In order to assess the anti-inflammatory effect of diclofenac drops (Voltaren Ophtha) we included a total of 37 PIG or PEXG (19 in the diclofenac and 18 in the placebo group) scheduled for ALT in prospective randomized placebo-controlled study. Visual acuity, tonometry, and LFCM flare measure were performed before, 3, 6 hours, 1, 2, 4, 7, 14 days after ALT. Topical diclofenac or placebo was given before and after ALT and then QID for a total of 4 days. Mean maximal flare increase was significantly less in the diclofenac group than in the placebo group (4.6 +/- 3.8 ph/msec v. 17.4 +/- 19 ph/msec; p less than 0.01). Flare increase compared to pre-ALT values was significant at 1 and 2 days after ALT in the placebo group only (p less than 0.02; p less than 0.05); no significant flare increase occurred in the diclofenac group.(ABSTRACT TRUNCATED AT 250 WORDS)