Abstract
Abstract: :
Purpose:To investigate the mechanism of acute angle-closure glaucoma, the morphological appearance of anterior chamber angles in patients with acute angle-closure glaucoma was studied using the ultrasound biomicroscopy (UBM). The eyes with narrow anterior chamber angles were also studied. Methods:Eight eyes of four patients with acute angle-closure glaucoma were observed using UBM ((mean age 78.00.7 (meanSEM)years )). In brief, three eyes of acute angle-closure glaucoma were scanned before and after laser iridotomy (LI) and one eye was scanned after peripheral iridectomy. Three of the fellow eyes were scanned before and after LI and one eye was scanned only before treatment. Then seventeen eyes of thirteen patients (mean age 68.32.2 years) with narrow angle that were considered to have a risk of acute angle-closure glaucoma based on the gonioscopic study were also scanned. Based on the scanning image, angle-opening distance at 250 (500) µm from the scleral spur ((AOD 250 (500)), trabecular-iris angle (TIA) were measured. Axial length of the eye balls and the lens thickness were measured by using the A-scan ultrasonography. Results:The appearance of angles in three eyes with acute angle-closure glaucoma showed the feature of pupillary block; bowing of iris, and the angle was closed in each quadrant. After releasing the pupillary block by LI or PI, bowing of iris did not present and the peripheral iris showed the feature of plateau iris configuration in all cases; the iris root is short and is inserted anteriorly, and the angle is still shallow. The angle of fellow eyes of acute angle-closure glaucoma and the eyes with narrow angle also showed the morphological features of plateau iris configuration after LI. The mean AOD250 in eyes with acute angle closure-glaucoma and the fellow was 53.726.4 (meanSEM) µm before LI and 152.041.7 µm after LI (ns, paired t-test) . AOD500 and TIA before LI were 43.326.3 µm and 2.831.82 degree, after LI they were 175.543.4 µm (P<0.05) and 16.24.62 degree (P<0.05). On the other hand these parameters in patients with narrow angle did not show the statically difference between before and after LI. The mean axial length of eye balls was 22.450.27 mm and lens thickness was 5.190.69 mm in patients with acute angle closure-glaucoma and the fellow eyes, and 22.120.16 mm and 4.930.09 mm in patients with narrow angle. Conclusion:Acute angle-closure glaucoma and the narrow angle due to pupillary block are associated with plateau iris configuration and lens bowing. Many plateau iris configurations present than expected in patients with narrow angle.
Keywords: 430 imaging/image analysis: clinical • 317 anterior chamber