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Meeting of the Queensland Branch of the Royal College of Ophthalmologists on Glaucoma for the New Millenium
Stradbroke Island, August 19th-22nd, 1999
Anne Brooks
A stimulating and interesting three-day meeting on the theme of Glaucoma for the New Millenium was held by the Queensland Branch of the Royal Australian College of Ophthalmologists at Couran Cove on South Stradbroke Island on August 19th-22nd, 1999. The lead speakers were Robert Weinreb of the University of California, San Diego, and Alphonso Anton of Segovia, Spain.
Robert Weinreb discussed what damages the optic nerve layer in glaucoma, with particular reference to the microcirculation. He also spoke on evaluating the nerve fiber layer in glaucoma, with specific reference to ophthalmoscopy, photography and scanning laser polarimetry. A clinical study by Graham Lee and Mark Loane, using the nerve fiber analyzer, followed this presentation. Weinreb also reviewed genetic testing in glaucoma, with particular reference to his work on Mt-1 and Mt-11. A further paper by him discussed the assessment of the optic disc in glaucoma, and highlighted confocal scanning laser ophthalmoscopy and optic nerve head topography, including the features of the HRT-2. Protection of the glaucomatous optic nerve was discussed and the concept of neuroprotection was reviewed. Weinreb's final paper was on whether prostaglandins lower intraocular pressure (IOP), in which he described in detail his recent research in this area, and in particular their effects on the extracellular matrix. Topical prostaglandin F2{224} treatment reduced collagen types I, III and IV in the monkey uveoscleral outflow pathway.
Alphonso Anton spoke first on the epidemiology of glaucoma, reviewing the published population-based surveys and describing his work in Segovia to date. He next spoke on functional deficits and visual field analysis and on new functional tests, including the short tests of SITA and TOP (Tendency Oriented Perimetry of the Octopus perimeter), short wavelength automated perimetry, and frequency-doubling threshold perimetry. Anton then comprehensively reviewed the conditions of pseudoexfoliation (PXF) and pigmentary glaucoma and reviewed the medical treatment of glaucoma. He also spoke on filtering surgery with and without antimetabolites, and reviewed the technique for standard trabeculectomy and trabeculectomy with antimetabolites, including specific recommendations to avoid complications. These included: 1. a limbal-based flap is less prone to leakages; 2. extreme caution to be taken when manipulating tissue; 3. tight scleral sutures; postoperative suture lysis if necessary; 4. tight and impermeable conjunctival sutures; 5. watch out for complications (hypotony, leakages, infection, etc.) and treat them.
Tony Molteno presented the results of the Otago glaucoma surgery outcome study: a long-term study of 289 cases of primary glaucoma treated by trabeculectomy from 1976 to 1995. This showed good control of IOP, however, visual acuity and visual fields declined steadily at a rate that gave a probability of a treated eye retaining useful vision until death of approximately 0.6. He also reported on the structure and function of draining blebs around Molteno implants. The fibrovascular inner bleb lining formed around Molteno implants is exposed to aqueous on its inner surface and to mesodermal tissue fluid on its outer surface. This layer develops a complex structure with specialized ground substance, vascular and connective tissue components, which together regulate the IOP. Molteno further reported on the Otago glaucoma surgery outcome study: a long-term study of primary open angle glaucoma treated by Molteno implant, in which 180 cases of primary open-angle glaucoma with additional risk factors present were treated with Molteno implants, and the results were compared with 238 cases of primary open-angle glaucoma without additional risk factors treated by trabeculectomy over the same period.
Ivan Goldberg gave an excellent presentation on an introduction to frequency doubled threshold perimetry with the principles and clinical application of this test. He also comprehensively reviewed approaches to glaucoma management following blunt trauma.
David Mackey extensively reviewed a large body of his work on genetics. He first spoke on predictive DNA testing for glaucoma with the GLC1A gene; experience with a large family. This study reported the attitudes of patients towards predictive DNA testing and concluded that predictive glaucoma gene testing is acceptable to patients and their families. Mackey then spoke on the phenotype of patients with the GLC1A Gln368STOP mutation from the inheritance study in Tasmania. This mutation is associated with primary open-angle glaucoma of variable age and onset. His final presentation was on the phenotypic variability in a large aniridia pedigree with a novel PAX6 1411delA mutation, where findings in affected individuals ranged from total aniridia to minimal anterior segment findings. Other findings included keratitis, cataract, glaucoma, disc anomalies and foveal hypoplasia.
Mark Loane introduced the meeting with an historical overview of the definition of the term glaucoma from 1635 to the present. He also presented a paper in the final segment on the surgical management of leaking filtering blebs, with his algorithm for their management.
John Kerr reviewed the history of the concept of apoptosis and described his work which led to his seminal paper defining apoptosis in the British Journal of Cancer in 1972.
Paul Mitchell presented results from the Blue Mountains eye study, and he overviewed the risk factors for open-angle glaucoma and ocular hypertension. Glaucoma was present in 3.0% of the population and increasing IOP, taking the higher of the two eyes, was strongly related to the prevalence of glaucoma. Other significant glaucoma risk factors, in order of magnitude, were a first-degree family history, myopia of one diopter or greater, diabetes, and hypertension. Mitchell also reviewed the other ocular signs which they had found to indicate an increased risk of glaucoma. PXF increased the risk of glaucoma and signed of PXF were associated with an increased past history of vascular events. Beta-peripapillary atrophy was also a significant risk factor for glaucoma in both non-myopic and myopic patients.
Julian Rait spoke on the early detection of glaucoma using the C-20-1 screening strategy of the Melbourne Visual Impairment Project, a population-based survey of eye disease, and reported that it was a rapid alternative to full-threshold FDT testing that detects glaucoma cases with a high sensitivity, and is highly specific at detecting ocular pathology. It appeared to be quite useful for population screening where false positive results need to be minimized. He also spoke on subtle phenotypes of the Axenfeld-Reiger syndrome. Subtle changes included sectors of faint iris stromal atrophy, prominent iris processes, and posterior embryotoxon.
Paul McCartney presented a nomogram for correction for IOP measurements for variation in corneal thickness, which is readily applicable clinically and corrects for the artificially high IOP seen in cases of very thick corneas or in thin corneas masking an elevated IOP.
Often the only surgery performed in glaucoma is cataract surgery and it is important to know the effect of this on the IOP and the visual field. A paper by Anne Brooks noted that cataract surgery causes a fall in IOP which is present at one year after surgery. The effect on the visual field is an improvement in the mean deviation, but an increase in the depth of the pattern standard deviation.
Mark Walland gave a presentation on the relative roles of medical therapy, laser and surgery in the management of glaucoma. He also spoke on whether timolol is bad for you, and the current place of cyclodestructive therapy in glaucoma management, with particular reference to the diode laser and its advantages.
Henry Lew described his experience with recovery of visual fields in patients following trabeculectomy surgery enhanced with 5FU, and in a case report of a young patient who underwent Scheie's operation.
The mechanism of uveoscleral outflow was reviewed by Sid Finnigan and Andrew Foster reviewed the place of laser trabeculoplasty.
Rodney Westmore reviewed non-filtering glaucoma surgery and, in another paper, reported on his encouraging results with viscocanalostomy. Allan Bank described his approach to glaucoma surgery with minimal risk.
Tim Roberts' paper on bleb morphology following adjunctive antimetabolite use in glaucoma filtration surgery discussed aqueous and bleb pressure dynamics, surgical techniques, and the effect of varying the antimetabolite treatment area in glaucoma filtration surgery.
Medical and surgery workshops also took place. This highly successful meeting, organized by Denis Stark and Mark Loane, was concluded after three very busy days.
