Comparison of intraocular pressure and anterior chamber angle changes between pilocarpine and laser peripheral iridotomy

Abstract

Aim: To compare intraocular pressure and anterior chamber angle changes between pilocarpine and laser peripheral iridotomy in primary angle closure. Materials and methods: In this clinical trial study, 34 eyes of 29 patients with primary angle-closure were prospectively enrolled between November 2015 and February 2016. Intraocular pressure and anterior segment optical coherence tomography were performed at three separate times: On the initial conditions, 3–5 days of administration of topical pilocarpine 2%, and 1 week after laser iridotomy. Anterior chamber angle parameters were the angle opening distance (AOD) and trabecular–iris space area (TISA). Results: The intraocular pressure reduction following pilocarpine administration was significant compared to laser iridotomy: 3.9 mm Hg (−32.5 to 0.20) vs 1.8 mm Hg (−33.5 to 2.30) (p = 0.002). Meanwhile, the increment of angle parameters following laser iridotomy was significant compared to pilocarpine. The AOD750 increment of both nasal and temporal quadrant following laser iridotomy was significant compared to pilocarpine: 0.13 mm (−0.27 to 0.28) vs 0.05 mm (−0.35 to 0.29) (p = 0.003) and 0.12 mm (−0.10 to 0.34) vs 0.04 mm (−0.27 to 0.19) (p = 0.002), respectively. The TISA750 increment of both nasal and temporal quadrant following laser iridotomy was also significant compared to pilocarpine: 0.05 mm2 (−0.06 to 0.20) vs 0.02 mm2 (−0.12 to 0.13) (p = 0.023) and 0.04 mm2 (−0.04 to 0.17) vs 0.01 mm2 (−0.14 to 0.18) (p = 0.012), respectively. Conclusion: Laser peripheral iridotomy widens the angle greater than topical pilocarpine, but topical pilocarpine lowers the intraocular pressure greater than laser iridotomy. These data suggest that pilocarpine has another mechanism to decrease the intraocular pressure in primary angle-closure, besides widening the angle.