Purpose: We have previously shown in rabbits that the intraocular pressure (IOP) spike caused by argon laser trabeculoplasty (ALT) is associated with an acute endothelin-1 (ET-1) release from the uveal tissue into the aqueous humour. In this study we investigated whether pretreatment with an ET(A) receptor antagonist (BQ-485) protects against the pressure spike induced by ALT, in the rabbit model.
Methods: Under general anaesthesia, 10 microl of 10(-5) M BQ-485 was injected into the anterior chamber of the right eye, and 10 microl of balanced salt solution (BSS) into the contralateral anterior chamber, for 12 pigmented rabbits. Five minutes later ALT (1,000 mW, 0.1 s, 100 spots over 360 degrees focused on the iris pillars) was performed on both eyes of each animal. IOP was measured before the injections (baseline value), and also 30 min afterwards using a Tono-Pen XL tonometer. Immediately after the second IOP measurement aqueous humour was aspirated for measurement of ET-1 concentration.
Results: The baseline IOP (mean +/- SD) was 8.08 +/- 1.73 mm Hg and 7.92 +/- 1.78 mm Hg for the right and left eyes, respectively (Duncan test, p > 0.05). At 25 min after ALT the IOP of the BQ-485-pretreated right eyes remained unchanged (7.83 +/- 2.44 mm Hg, p > 0.05) but the IOP of the BSS-pretreated left eyes at 30 min increased significantly to 10.67 +/- 4.70 mm Hg (p < 0.05 for comparisons both with the corresponding baseline value for the same eye, and with the IOP of the contralateral eye at 30 min). There was no difference in aqueous humour ET-1 concentration between the corresponding right and left eyes (paired t test, p > 0.05).
Conclusion: Intracameral BQ-485 pretreatment protected against the ALT-induced acute IOP elevation, but did not influence the laser-induced ET-1 release. This suggests that ET(A )receptor antagonists may potentially have a therapeutic role in the prevention of laser-induced IOP spikes.
Copyright 2002 S. Karger AG, Basel