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“A week is a long time in politics.”1 Those who waited for a “final result” in the recent American presidential elections will have been only too familiar with this saying, given the frequent, sometimes hourly, changes in the fortunes of the protagonists. However, in contrast with this, the time frame to a “final result” in most patients with glaucoma is much longer. It may take us our whole working careers to learn the lifetime natural history of one of our adult patients with glaucoma or other chronic conditions such as uveitis. In the case of the paediatric glaucoma clinic at Moorfields Eye Hospital that has been running for five decades, it is a sobering thought that it will take the careers of three consultants to see one patient through their lifetime! Yet the very thing patients with glaucoma want is for us to gaze into a crystal ball and predict their fate in the distant future, and help guide them towards the treatment regimen that has the best risk-benefit ratio for them as individuals.
In this issue of the BJO (p 689) Broadwayet al publish the results of Molteno tube drainage surgery from one centre with a mean follow up of 43 months, ranging from 6 months to 10 years of follow up. This group of patients had a mixture of diagnoses that increased their risk of surgical failure and almost 50% of them had already failed one or more trabeculectomy which confers a much reduced future success rate.2 In addition, the patients had a very high preoperative intraocular pressure of 46.3 mm Hg which would be expected to lead to significant visual loss in a large number of these patients over the course of this study.
With tube implantation approximately 80% of patients had intraocular pressure less than 21 mm Hg a year after surgery, and approximately 50% of patients no longer required eye drops. However, the importance of length of follow up is clear as these figures fall to approximately 70% and 35% at 2 years and 65% and 25% at 4 years. This is particularly important as the mean age of the patients was only 46 years, with a life expectancy of at least two decades. Over the course of the study 21% of patients had a fall in Snellen visual acuity. However, in common with most of these types of studies, data on nerve and field progression are very difficult to obtain.
These results are not dissimilar to other studies on Molteno tubes,3-7 although it is difficult to compare studies because of the variation in patient groups. Could the long term success rates for patients now be improved by changing tube techniques such as increasing tube plate area3 ,5 ,8 or using adjunctive antimetabolites9 without increasing complication rates? Would other modalities of surgical treatment such as diode cyclophotocoagulation or high dose mitomycin trabeculectomy give better long term results?
What these results do teach us is that a long term perspective is essential when dealing with patients with chronic disease. Any new treatments or surgical techniques that promise short term gains must prove themselves in the long term. How are we to gain this knowledge which is essential if we are to guide our patients safely through into the long term?
First and foremost, we need to constantly learn from our personal experience, continually auditing the results of the various treatments and surgery we carry out, not just in the short but in the long term. It is this process that bestows on us that elusive but most sought after attribute known as experience. However, this has also to be combined with the information available from large, long term prospective studies10 ,11 of various treatments which can also provide long term information or optic disc and field loss progression which individuals cannot easily gather and analyse on their own. Although these studies are very time consuming in staffing and resources they will provide the long term data available from no other source.
A week may be a long time in politics, but a year is a short time in glaucoma. We require information from long term studies to provide us with the information to predict the fate of our patients. This will ultimately allow us to accurately determine the best management for every one of our patients in the future.
We are grateful to the Medical Research Council (G9330070), the International Glaucoma Association, and Moorfields trustees who support our clinical glaucoma and wound healing research programme.
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