Abstract
Abstract: :
Purpose:To analyse the effect of brimonidine on angle opening in light and dark conditions, and determine whether a brimonidine–induced reduction in mydriasis decreases the extent of dark–induced angle closure in eyes with primary angle closure or primary angle closure glaucoma.. Methods:A prospective study was carried out in 17 eyes of 10 consecutive Chinese patients diagnosed as primary angle closure suspects, primary angle closure or primary angle closure glaucoma. All patients underwent complete ophthalmologic examination, including ultrasound biomicroscopy (UBM) of all four quadrants in light and dark. One drop of brimonidine was then instilled into each eye and the examination repeated 1 hour later. Primary outcome measures included UBM measurements of the area of angle recess (ARA), angle opening distance at 250µm (AOD250) and at 500µm (AOD500) from the scleral spur. Secondary outcome measures included intraocular pressures and any immediate side effects of brimonidine. Results:Without brimonidine there was a significant reduction in all three UBM measures of anterior chamber angle, ARA, AOD250 and AOD500, in the dark compared to the light. Treatment with brimonidine successfully blocked this dark–induced angle narrowing of all three measures. The eyes of diabetic subjects had significantly less angle narrowing in the dark than those of non–diabetics, and brimonidine showed a correspondingly smaller effect in maintaining angle opening in diabetics. Conclusions:We have demonstrated that brimonidine successfully abolishes dark–induced angle narrowing in subjects with narrow angles and established angle closure.
Keywords: imaging/image analysis: clinical • pharmacology • clinical (human) or epidemiologic studies: treatment/prevention assessment/controlled clinical trials