A New Acute Attack of Angle Closure Glaucoma Animal Model with Healon 5

Acute angle closure glaucoma (AACG) is an ocular emergency and sight -threatening disease in which the intraocular ocular pressure (IOP) rises suddenly due to blockage of aqueous humor outflow. It can cause permanent loss in visual acuity and visual field. In animal study, the well-established model to study AACG is by fluid infusion and by adjusting the bottle level, a high IOP can be induced in a few seconds. However, there is no blockage of aqueous outflow and the pressure rise is unrealistically fast. To mimic human AACG, we suggest to use Healon 5, an ophthalmic viscosurgical device, which is injected intracamerally to block the aqueous outflow. The IOP is allowed to build up naturally. We found that, with this technique, the IOP elevated at a rate of 0.57 mmHg/min before it hit 40 mmHg, which is considered as AACG in human. The maximum IOP registered was above 70 mmHg. Thinning of retinal nerve fiber layer (RNFL) and neural cells lost were seen. Visual function evaluated by ERG showed reduction in a-wave, b-wave, photopic negative response (PhNR) and oscillatory potentials (OPs) activities. In conclusion, Healon 5 is effective in inducing acute transient rise in IOP which mimics human AACG.