Acute glaucoma is an ocular emergency and sight -threatening disease which is caused by a sudden increase in intraocular ocular pressure (IOP) due to blockage of aqueous humor outflow. Acute glaucoma can result in permanent loss of visual acuity and visual field (VF). Prophylactic or therapeutic medicine is rare for acute glaucoma.
In animal studies, a well-established model to investigate this acute IOP spike is by fluid infusion and adjustment of the fluid level to induce high IOP within a few seconds. However, there is no blockage of aqueous outflow and the increase in intraocular pressure is unrealistically rapid. To mimic the IOP profile in human acute glaucoma attack, we propose the use of an ophthalmic viscosurgical device (OVD), Healon 5 (AMO, Santa Ana, CA, USA) which is injected intracamerally to block aqueous outflow. The IOP is allowed to increase naturally inside the globe.
We found that Healon 5 can induce an acute elevation in IOP with very similar characteristics to those observed in humans. For example, the IOP profile during the attack, changes in the anterior segment and retinal nerve fibre layer (RNFL) thinning are all consistent with findings in human acute angle closure glaucoma (AACG). We believed that our new model can more accurately reflect acute glaucoma than other animal models.
Based on these findings we further tested the neuroprotective effect of Lycium barbarum polysaccharides (LBP) on retinal neurons against an acute rise in IOP (attack) with the new model. L. barbarum is an herb that has been used in Chinese medicine for thousands of years. The fruit of this plant is believed to be good for the health of the eyes. In our study we found that oral administration of LBP preceding an acute glaucoma attack can preserve the visual function of the animals despite the loss of neurons in the retinal ganglion cell layer (RGCL). L. barbarum intake seems to inhibit secondary cell death and progression of the disease.
In conclusion, we had successfully established a new acute glaucoma attack animal model by intracameral injection of Healon 5. This model more closely resembles the condition observed in human acute glaucoma. We also found that LBP has a prophylactic neuroprotective effect against an acute glaucoma attack in animals. It can protect the visual function and possibly inhibit secondary cell death. Oral consumption of LBP as a health supplement may provide extra benefit to people who are at high risk of developing acute glaucoma, in addition to the protective effects of LBP against other diseases. / published_or_final_version / Anatomy / Master / Master of Philosophy
| Identifer | oai:union.ndltd.org:HKU/oai:hub.hku.hk:10722/174369 |
| Date | January 2012 |
| Creators | Lau, Yuk-fan, Silvania., 劉玉芬. |
| Contributors | Lai, JSM, So, KF, Lo, ACY |
| Publisher | The University of Hong Kong (Pokfulam, Hong Kong) |
| Source Sets | Hong Kong University Theses |
| Language | English |
| Detected Language | English |
| Type | PG_Thesis |
| Source | http://hub.hku.hk/bib/B47309325 |
| Rights | The author retains all proprietary rights, (such as patent rights) and the right to use in future works., Creative Commons: Attribution 3.0 Hong Kong License |
| Relation | HKU Theses Online (HKUTO) |
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