Effect of preoperative topical diclofenac on intraocular interleukin-12 concentration and macular edema after cataract surgery in patients with diabetic retinopathy: a randomized controlled trial

AIM To determine if preoperative treatment with a topical non-steroidal anti-inflammatory drug (NSAID) lowers the concentration of intraocular interleukin (IL)-12 and the incidence of postoperative macular edema in patients with non-proliferative diabetic retinopathy undergoing cataract surgery. METHODS A total of 55 patients were randomized to diclofenac (n=27) or placebo (n=28). Patients receiving diclofenac started preoperative treatment with 0.1% topical diclofenac four times a day 7 days before cataract surgery and the therapy was discontinued 30 days after surgery. Patients in the control group were administered placebo 7 days preoperatively and a standard postoperative therapy with 0.1% topical dexamethasone four times a day for 30 days after surgery. All patients received postoperative antibiotic prophylaxis with tobramycin eye drops four times daily for 30 days. Seven days before the cataract surgery, on the day of surgery, and 1, 7, 30, and 90 days after surgery, central foveal thickness (CFT) was measured with optical coherence tomography (OCT) and the aqueous humor was sampled at the beginning of cataract surgery for the analysis of IL-12 concentration. Due to loss to follow-up and insufficient aqueous humor samples, the data of 3 patients treated with diclofenac and 8 patients receiving placebo were not analyzed. RESULTS The aqueous humor IL-12 concentration was significantly lower in the diclofenac group than in the placebo group (t=-2.85, p=0.007). The diclofenac group had a significantly smaller increase in CFT after phacoemulsification (F=13.57, p<0.001). CONCLUSION Patients preoperatively treated with diclofenac had significantly lower intraocular levels of IL-12 and a lower increase in CFT, which indicates that a combination of preoperative and postoperative treatment with a topical NSAID may lower the incidence of postoperative macular edema in patients with diabetic retinopathy.