Ying Hong1,2, Chao Wang1,3,4, Ralitsa Loewen1, Susannah Waxman1, Priyal Shah1, Si Chen1,3, Hamed Esfandiari1,5, Nils A Loewen6,7. 1. Department of Ophthalmology, University of Pittsburgh Medical Center, Pittsburgh, PA, USA. 2. Department of Ophthalmology, Peking University Third Hospital, Beijing, China. 3. Department of Ophthalmology, Xiangya Hospital, Central South University, Changsha, Hunan, China. 4. The Third Xiangya Hospital of Central South University, Changsha, Hunan, China. 5. Department of Ophthalmology, Northwestern University, Chicago, IL, USA. 6. Department of Ophthalmology, University of Pittsburgh Medical Center, Pittsburgh, PA, USA. loewen.nils@gmail.com. 7. Department of Ophthalmology, University of Würzburg, Würzburg, Germany. loewen.nils@gmail.com.
Abstract
PURPOSE: To establish the extent of anterior chamber angle circumference needed to maintain a physiological outflow facility (C). This could create a model to investigate focal outflow regulation. METHODS: Twenty anterior segments of porcine eyes were assigned to five groups, each with a different degree of cyanoacrylate-mediated angle closure: 90° (n = 4), 180° (n = 4), 270° (n = 4), 360° (n = 4), and four unoccluded control eyes. The outflow facility was measured at baseline, 3, 12, 24, and 36 h after angle closure. Outflow patterns were evaluated with canalograms and the histomorphology was compared. RESULTS: Baseline outflow facilities of the five groups were similar (F = 0.922, p = 0.477). Occlusion of 360° induced a significant decrease in facility from baseline at all time-points (p ≤ 0.023 at 3, 12, 24, and 36 h). However, no difference from baseline was found in any of the partially occluded (0-270°) groups (F ≥ 0.067, p ≥ 0.296 at 3, 12, 24, and 36 h). The canalograms confirmed the extent of occlusion with flow through the unblocked regions. Histology revealed no adverse effects of blockage on the TM or aqueous plexus in the unoccluded angle portions. The unoccluded TM appeared normal. CONCLUSION: Cyanoacrylate-mediated angle occlusion created a reproducible angle closure model. Ninety degrees of unoccluded anterior chamber angle circumference was sufficient to maintain physiological outflow. This model may help understand how outflow can be regulated in healthy, nonglaucomatous TM.
PURPOSE: To establish the extent of anterior chamber angle circumference needed to maintain a physiological outflow facility (C). This could create a model to investigate focal outflow regulation. METHODS: Twenty anterior segments of porcine eyes were assigned to five groups, each with a different degree of cyanoacrylate-mediated angle closure: 90° (n = 4), 180° (n = 4), 270° (n = 4), 360° (n = 4), and four unoccluded control eyes. The outflow facility was measured at baseline, 3, 12, 24, and 36 h after angle closure. Outflow patterns were evaluated with canalograms and the histomorphology was compared. RESULTS: Baseline outflow facilities of the five groups were similar (F = 0.922, p = 0.477). Occlusion of 360° induced a significant decrease in facility from baseline at all time-points (p ≤ 0.023 at 3, 12, 24, and 36 h). However, no difference from baseline was found in any of the partially occluded (0-270°) groups (F ≥ 0.067, p ≥ 0.296 at 3, 12, 24, and 36 h). The canalograms confirmed the extent of occlusion with flow through the unblocked regions. Histology revealed no adverse effects of blockage on the TM or aqueous plexus in the unoccluded angle portions. The unoccluded TM appeared normal. CONCLUSION:Cyanoacrylate-mediated angle occlusion created a reproducible angle closure model. Ninety degrees of unoccluded anterior chamber angle circumference was sufficient to maintain physiological outflow. This model may help understand how outflow can be regulated in healthy, nonglaucomatous TM.
Authors: P J Foster; T Aung; W P Nolan; D Machin; J Baasanhu; P T Khaw; P-H Alsbirk; P S Lee; S K L Seah; G J Johnson Journal: Br J Ophthalmol Date: 2004-04 Impact factor: 4.638
Authors: Hana Levkovitch-Verbin; Harry A Quigley; Keith R G Martin; Danielle Valenta; Lisa A Baumrind; Mary Ellen Pease Journal: Invest Ophthalmol Vis Sci Date: 2002-02 Impact factor: 4.799