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The EGS 2000 millennium meeting, VIth congress and 20th anniversaryJune 25th-29th, London, UK
The EGS 2000 meeting was greeted by the overwhelming response of close to 1500 participants. The meeting was special in many aspects: many short (three-minute) presentations backed by posters; the extensive use of an interactive question and answer system; more discussion time than speaker time; afternoon teaching sessions; a vibrant social program; the London venue, etc. It worked. The enthusiasm was enormous. In this issue, IGR presents:
1. The point-wise impressions of the chairmen:
Session 1: Subjective assessment
Session 2: Ocular imaging
Session 3: Genetics and childhood glaucoma
Session 4: Blood flow and miscellaneous
Session 5: Medical treatment
Session 6: Antiproliferatives
Session 7: Surgery and NPFS
Session 8: Nonpenetrating filtering surgery2. A selection from the interactive question and answer system
Easy and important reading for the glaucoma enthusiast!
The point-wise summaries of the chairmen:
Session 1: Subjective assessment
by C. Johnson and A. Heijl
• (Light threshold) light intensity correlated better with neuroretinal rim area than threshold values expressed in dB in a small series of glaucomatous, suspect and normal eyes.
• Not surprisingly, threshold values obtained at individual test point locations with FDT perimetry were statistically correlated with threshold values obtained with standard W/W perimetry (r2 = 0.60; p < 0.001) at the corresponding locations.
• An optimized modified binary search (MOBS) and a maximum likelihood strategy (ZEST) could both produce a reduction in FDT test time of 40-50% compared to the standard FDT MOBS strategy with no increase in test-retest variability.
• FDT screening was tested in a large community of 739 patients. High sensitivity glaucoma cases were detected, but in the majority of patients who screened positively, there were explanations other than glaucoma for their field defects.
• The dB scales of FDT and standard Humphrey Full Threshold W/W perimetry are highly correlated, but have some systematic differences. FDT seems to score lower at the 'normal' end of the spectrum and 'higher' in seriously damaged eyes. Thus, the FDT dynamic range is somewhat smaller than that of standard perimetry.
• Sixty-one ocular hypertensives with normal W/W perimetry scores were tested with SWAP. The eyes of each individual were compared. The neuroretinal rims were statistically different in eyes in which SWAP showed a mean sensitivity asymmetry of > 2 dB between the eyes, compared to eyes with symmetrical SWAP sensitivities.
• A larger percentage of 160 ocular hypertensive eyes with SWAP and/or RNFL defects developed visual field defects on conventional perimetry within three years of follow-up than hypertensive eyes with normal SWAP and RNFL photography. The majority of eyes with abnormal SWAP or RNFL results still had normal standard fields after three years.
• Forty-eight patients with open-angle glaucoma and ocular hypertension were tested with SITA Fast and TOP. The mean test time for TOP was shorter (2.45 minutes) than for SITA Fast (4.10 minutes). MD values were correlated (r = -0.80). No point-wise analysis was provided.
• Sixty-one normal pressure glaucoma eyes were subjected to drainage surgery. Eyes that showed a larger percentage drop in IOP showed significantly less progression in the subsequent six months than eyes with smaller drops in pressure.
Session 2: Ocular imaging
by J. Caprioli• The expected correlations between axon counts and C/D ratio and visual field status were revealed.
• The most valuable optic disc variables, from conventional photos or other types of assessment, were vertical C/D ratio corrected for disc size and total rim area. Correction for disc size is important.
• No imaging method was demonstrated to be superior to qualitative disc evaluation. Heidelberg retina tomograph and disc photos were similar for detecting early damage; OCT and GDx were less valuable, but still useful.
• A significant component of the GDx measurement appears as a signal artifact from the polarizing properties of the cornea.
• A strong reduction of IOP in patients with early glaucoma causes a change in the optic nerve structure (apparent improvement), associated with long-term improvement in visual function. Perhaps this should be our treatment goal.
• Caprioli adds a note that is unrelated to imaging, but no less interesting: TM changes appeared to follow, and not precede, IOP rises in primary open-angle glaucoma, but not in pseudo-exfoliation glaucoma.
Session 3: Genetics and childhood glaucoma
by Peng Khaw• The lifetime risk when there is a family history of glaucoma is 20-50%, depending on population.
• Patients often do not know of a family history of glaucoma, even in a close relation.
• Family history and risk are similar in various types of glaucoma including normal tension glaucoma, pigmentary, and primary angle closure glaucoma.
• IOP measurements alone may not be enough, especially if inhalational anesthesia is used (IOP differences of up to +30 mmHg).
• Axial length measurements may be required depending on the characteristics and severity of the glaucoma in the child.
• Spontaneous resolution of congenital glaucoma is possible (but rare).
• Antimetabolites may increase the surgical success, but also the complications.
• Trabeculectomy may be useful in juvenile glaucoma, at least in Japanese patients.
• Diode laser treatment is useful for very refractory childhood glaucoma, but multiple treatments may be required, and medical treatment has to be continued as pressure lowering is not as much or as sustained as in a drainage procedure.
Session 4: Blood flow and miscellaneous
by George Lambrou• The interest of the glaucoma community in the role of blood flow disturbances in the pathogenesis of glaucoma seems as high as ever, despite the well-known uncertainties about flow measurement techniques. Even though formal proof of this role remains somehow elusive, the bulk of indirect evidence accumulated over the years is huge and, to many, convincing.
• Ninety-three percent of the audience replied YES to the question, "Do you believe that compromised blood flow plays a role in optic nerve damage in glaucoma?"
• As an example of indirect evidence, Kitazawa studied patients with asymmetric disturbances in ocular perfusion pressure (OPP) and asymmetric visual field mean defect (MD). There was an overwhelming majority of patients in whom the asymmetries were pointing in the same direction (lower OPP in the eye with worse MD) and, in the few cases in which OPP was better in the eye with the worse MD, color Doppler imaging revealed significant ocular hemodynamic abnormalities.
• Probably the most important paper in the session was that by Galassi and Sodi. It was, to my knowledge at least, the first piece of direct evidence ever presented of a causative role of blood flow disturbances in the progression of visual field defects. In a retrospective seven-year study of color Doppler imaging data recorded every six months in 37 patients, Galassi and Sodi found that the risk of defect progression was three times higher in patients who originally presented with a high resistive index (Ri). The relevance of this study comes from the fact that, at the time of the first Ri recording, there was nothing other than Ri to distinguish the 25 patients who would progress from the 12 who would remain stable over the next seven years.
• Ocular pulse amplitude, as measured with Robert's, 'smart lens', divides normal pressure glaucoma patients into two categories: those (the majority) with an OPA significantly lower, and those with an OPA significantly higher, than normal. If confirmed, these results will require a distinction between two subgroups of normal pressure glaucoma patients, possibly with different pathogenic mechanisms.
• Age affects the capillaries of the optic nerve head, causing an increase in blood velocity and a decrease in volume, as if the number and/or diameter of the capillaries decreases with age.
• Following latanoprost instillation in healthy volunteers, Man et al. found a 26% decrease in IOP and a 20% increase in pulsatile ocular blood flow, the latter in 15 of 19 eyes. This once again raises the ever-present question in such trials: if under acute treatment you observe an increase in ocular blood flow concomitant to IOP decrease, how do you distinguish a genuine effect on blood flow from a simple improvement in ocular hemodynamic conditions due to the increased perfusion pressure resulting from the lower IOP?
• Conscious of this problem, 83% of the audience answered YES to the question "Is it important to evaluate the effects of anti-glaucoma drugs on ocular blood flow?" And 81% replied that they would use, either in selected cases (69%) or in most glaucoma patients (21%), a drug which would genuinely improve blood flow, even it had no effect on IOP.
• The most surprising presentation of the session was: Helicobacter pylori infection of the stomach is highly correlated to glaucoma (a surprising odds ratio of 8.22, p = 0.0002). Should we be looking at oral antibiotics rather than at new generations of hypotensive eye drops as the next breakthrough in glaucoma prevention?
