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Reinhard Burk
Impressions from the closed meeting of the European Glaucoma Society
Würzburg, Germany, September 3-4, 1999
The two-day conference was held in the charming old university town of Würzburg in Germany, organized by Professor Franz Grehn under the auspices of the Education and Scientific Committee of the European Glaucoma Society (EGS).
Upon invitation, a total of 34 papers and 18 posters were presented. The main topics included mechanisms in glaucoma, glaucoma surgery, wound healing, as well as advances in medical treatment. Where are we today with respect to early diagnosis, follow-up, and long-term results of professional care for glaucoma patients? Having in our hands a battery of high-precision tools for the early diagnosis and evaluation of risk of glaucoma, we must decide whom to treat and which treatment options would best be suited to the individual patient, while taking into account aspects regarding quality of life.
Preliminary data from the Swedish EMGT study, which enrolled over 33,000 inhabitants of Malmö in a screening protocol, suggest that the prevalence of glaucoma is associated with intraocular pressure (IOP), but that myopic eyes in particular are at high risk of developing glaucomatous damage at statistically normal IOP readings. While diabetes is not a risk factor, a family history of glaucoma almost doubles the risk of glaucomatous damage. A striking morphological features associated with glaucoma is the presence of optic disc hemorrhages. These appear 50 times more frequently in glaucoma patients compared to control subjects. In the long run, this study will provide insight into the spontaneous course of the disease and will clarify the importance of treatment efforts. Unless other options and treatment modalities are available and have been proved to be effective, IOP reduction is still the goal of treatment. Beyond today's office IOP data, in the future, real IOP related risk estimations may be based upon telemetric data obtained from miniaturized IOP sensors which are coupled to the haptics of intraocular lenses.
With respect to medical therapy, different new classes of IOP lowering drugs are available. For a given class, modifications in the formulation can improve the efficacy/systemic side-effect ratio. While switching to other classes is indicated if pressure reduction does not seem to be adequate, statistical data on sales from prescriptions indicate that adding new drugs is more common than changing the medication. This indicates the need for the EGS to extend its educational efforts.
For those patients in whom medical treatment is not or no longer considered to be the approach of choice, glaucoma surgery is an alternative line of treatment. However, the surgical intervention which is safely performed, not only in the hands of a few gifted surgeons, and proves to be effective for many years (lifelong?) in all cases, for different types of glaucoma, without the need of additional medication, still has to be developed. While non-penetrating filtering procedures and their modifications are characterized by a low postoperative risk profile, the amount of IOP reduction which can be achieved in the long run is questionable and still under debate. For advanced stages of glaucomatous damage and for cases of normal-tension glaucoma, a standard trabeculectomy with adjunctive antimetabolites might be the procedure of choice, at the risk of a higher incidence of postoperative complications. As has been reported, success rates entirely depend upon the definition of a favorable outcome: a postoperative pressure of 3 mmHg at six months might represent a statistical success in one study, while it would be considered a complication (hypotony) in another. We are now looking forward to EGS study outlines and proposals for the classification of outcomes.
The active modulation of wound healing processes by photodynamic therapy or by the use of specific antibody applications against growth factors, may well be of help in finding more effective solutions for improving the long-term results of filtration surgery. New approaches in laser surgery, such as intrastromal clear cornea keratostomy with subconjunctival mitomycin injection, seem to be promising. For some cases of refractory glaucoma, cyclodestruction with the diode laser, which is quick and easy to perform, may have a place among treatment options if it is considered a last resort in a few cases.
It should be emphasized that the ample time for discussions at this scientific conference was of great help in stimulating the active participation of the audience. Furthermore, personal experiences and opinions could be frankly exchanged at the get-togethers held at the Juliusspital winery and the Baroque castle 'Residence' on Saturday evening.
The purpose of the meeting, which was to stimulate the exchange of scientific ideas and to study results in an open-minded atmosphere, was more than fulfilled. The EGS and Professor Franz Grehn together with his team are to be congratulated for having organized this meeting dedicated to the improvement of the care of glaucoma in all its forms.
Reinhard O.W. Burk
This 2-day meeting addressed invited glaucoma researchers and their coworkers in a limited number to stimulate discussion and mutual exchange of ideas in a personal atmosphere. All speakers restricted their result presentation to 7 minutes and an equal time of discussion was allowed. This concept turned out to be very stimulating for exchange of ideas and new concepts.
Summary of First Sesson on Saturday morning.
The last 25 years the trabeculectomy operation has been king of glaucoma surgery. What we have heard this morning are the claims for two pretenders to this throne. The first pretender is the deep sclerectomy and the second is the viscocanalostomy. In the first procedure is significant wedge of sclera and the outer wall of the canal Schlemm are removed and the superficial scleraltlap is loosely sutured back into the position if it is sutured at all. Modifications include a laser to remove the tissue down to the canal of Schlemm and the insertion of collagen wigs. The second procedure of viscocanalostomy which by the injection of Healon® made or similar substance into the canal of Schlemm opens up the outflow channels to the aqueous veins from the trabecular meshwork. In this procedure the scleralflap is tightly sutured. The papers we have heard included a case control by Wishart and Wishart, which compared the two procedures and one by Reinhold Burk, which carried out both procedures at the same time, we heard from Dr. Megevand from Geneva a follow-up of viscocanalostomy and Alain Béchetoille a follow-up of non-penetrating trabeculectomy. Dr. Lieb showed us how you can modify the non-penetrating sclerectomy by using Erbium-YAG-Laser. Finally there were three papers, where in randomized prospective studies a trabeculectomy was compared firstly against the non-penetrating deep sclerectomy by Yves Lachkar and Dr. Chisehta and secondly against the viscocanalostomy by Dr. Carassa.The general consensus was that these operations did not produce such good medium-term intraocular pressure control as trabeculectomy. However we need to consider whether that this is the outcome measure that we want for our patients. The primary outcome measure must be prevention of further visual field loss and this has yet to be addressed. Other outcome measures would include the incidence of cataract formation and the incidence of bleb related complications, both the comfort of the patients point of view and infections. These clearly need to be addressed in prospective studied.
A strong part of the audience showed that there are enough people present today who would be prepared to be involved in a prospective control study comparing viscocanalostomy and deep sclerectomy with trabeculectomy. It is up to the EGS to organize such a study to demonstrate once and for all whether trabeculectomy remains king.
R. Hitchings
Comment on non-penetrating Filtering Surgery at the European Glaucoma Society Closed Meeting by Carlo Traverso
It appears from published works and those presented here that NPFS has a great potential for bringing the immediate postoperative complications back to close to nil. This is a major and long overdue achievement. The long-term data on IOP, where available, do not seem to lead to the low teens, at least without antiglaucoma drugs and antimetabolites. While I share the enthusiasm for these techniques, I do have the following question: am I trading a less complicated postoperative course for a less strong IOP lowering effect?Comment by E. Lutjen-Drecoll
1. The correlation between the amount of plaque material in the trabecular meshwork and nerve fiber loss in the optic nerve indicates that there are common factors responsible for both changes.
2. Intraocular pressure is secondary to increases in plaque and PEX material. Therefore, other factors are responsible for changes in the trabecular meshwork.
3. Transforming Growth Factor b2 (TGFb2) is increased in a number of glaucomatous eyes.
4. The in vitro treatment of trabecular cells with TGFb2 increases the formation of fibronection and of tissue transglutaminase, an enzyme crosslinking extracellular matrix components, so that they are no longer digestible by metalloproteinases.
5. In vitro TGFb2 treatment induces the expression of aB-crystallin, a stress protein that is also increased in a number of glaucomatous eyes. If these changes also occur in vivo, TGFb2 could be one of the factors leading to glaucomatous changes.
Carlo Traverso
Comment on Flow Chart VIII of the European Glaucoma Society Guidelines
The therapeutic trial for glaucoma medications
When not effective, do not insist on treatment
In order to preserve visual function, current therapy is to lower the intraocular pressure (IOP). The efficacy of topical treatment with glaucoma drugs should therefore first be verified by their effect on IOP. When the monotherapy of choice is not effective on IOP, it should be discontinued rather than an additional drug being added to it. When the effect is enough to reach the target IOP, monotherapy should be maintained and monitored. If the effect is sizable, but not enough to satisfy our desire for a given IOP level, then the treatment can be continued and a second drug added. The same process for verifying its efficacy should be applied to the second drug, and likewise to a third drug.
The apparently naive treatment principle of, 'when not effective on IOP, change it rather than add a second' is not always practised. One of the difficulties is the definition of 'effective on IOP'. Fortunately, from the abundant literature on the subject, we know the average IOP response to be expected from each drug; this can be of great help in determining whether or not our individual patient is a responder to that molecule. If a drug has an average IOP lowering effect of 25%, there is probably no point in maintaining a patient on it unless it has a very similar effect on him/her. What is the point of keeping a patient on a drug he/she is not responding to with at least the average expected effect, since, statistically speaking, 50% of them should do better than average?
Carlo E. Traverso
