Phenylephrine and pilocarpine in the treatment of post-operative irido-corneal adhesion.

Following cataract surgery, entrapment of the iris within the surgical wound is often managed by intensive use of miotics. As the radial fibres stretch, only a small amount of fraction is exerted upon the entrapped iris. Application of a combination of phenylephrine and pilocarpine drops causes simultaneous contraction of the pupil sphincter and the radial muscle fibres. This study investigated the relative magnitude of forces induced in the iris periphery by pilocarpine and phenylephrine and the effectiveness of adding g. phenylephrine 10% to g. pilocarpine 4% drops in the treatment of postoperative irido-corneal adhesions. The investigation was divided into two parts. First, the forces induced in the iris periphery upon exposure to pilocarpine and phenylephrine were measured in 6 cadaver irises. The mean force was 27.5 +/- 5.7 x 10(-3) N for pilocarpine and 23.3 +/- 4.0 x 10(-3) N for phenylephrine. The combination of the two drugs produced a force of 54.2 +/- 6.6 x 10(-3) N (p < 0.05). In the second part of the study intensive pilocarpine 4% drops were administered to 17 patients who had iris-wound entrapment on the first post-operative day. Patients with persistent adhesion were commenced on intensive g. phenylephrine 10% and assessed after 90 minutes. Of the 17 patients, 6 responded to pilocarpine drops alone; in a further 7 the irido-corneal adhesion was released only by the addition of phenylephrine drops, and in 4 patients drops were ineffective in relieving the adhesion. This study indicates that addition of phenylephrine 10% to pilocarpine 4% drops enhances the effectiveness of pharmacological treatment of post-operative irido-corneal adhesion.