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Abstract #15574 Published in IGR 1-3
Molteno implants: the principles of bleb management.
Molteno AC; Dempster AG; Carne AAustralian and New Zealand Journal of Ophthalmology 1999; 27: 350-2
Drainage systems depend on synthetic polymer which are inert and compatible with living tissue. Most present day drainage system use a tube and plate. The function of the plate is to initiate the formation of a large bleb of standard size. This bleb becomes distended by aqueous and developes a specialized vascular lining. It is this fibrovascular bleb lining that is responsible for regulating the escape of aqueous. This article coveres some of the experiences of the authors, particularly of Tony Molteno. They first discuss the aspect of patient age. Acording to these authors patients under two or over 60 years usually develop thin walled blebs whereas between these two age limits blebs are usually thick walled. So the intermediate age group has an indication for large implants and anti-inflammatory medications. The next item that is discussed is the severity of glaucoma. The authors feel that it is important to hold the intra-ocular pressures by all means at normal pressure levels. They feel that the bleb has a better development at these pressure levels. In fact they suggest that at higher levels there is more inflammation causing a more thick walled bleb and les drainage. Both the patient age and the level of IOP are important. The IOP level however is much more significant. They stress the importance of IOP management after the operation. Over the age of 60 the majority of cases show a tendency towards improve drainage and fall in IOP over time. The authors also compared trabeculectomy in patients without additional risk factors compared to Molteno implants in patients with risk factors. In bothe cases the mean intraocular pressure at about one year was 15 mmHg. Pressures under 21 mmHg without medication were seen in 75% of trabeculectomies and 70% of Molteno implants. An additional 15 % was controlled with medication after trabeculectomy and an additional 29% after Molteno implants. They report failures after trabeculectomies of 9% as opposed to 2% after Molteno implants. The mean follow-up in both series is 7 years with a range between 1 and 19 years. They conclude that in this comparative study both techniques produced about similar results. They furthermore conclude that the permeability of the bleb-lining is essential for long-term control of IOP. The important period is some 5-6 weeks after onset of drainage. The inflammatory response in that period requires careful attention. It is important to select the drainage area according to the patients age and severity of the glaucoma. Preformation of the bleb by using a vicryl tighter to occlude the tube is necessary. IOP should be kept at normal levels. Use of anti-inflammatory medications to control bleb-fibrosis is mandatory.
Department of Ophthalmology, University of Otago, Dunedin, New Zealand.
Classification:
12.8.2 With tube implant or other drainage devices (Part of: 12 Surgical treatment > 12.8 Filtering surgery)
