Report on the Subspecialty Day of the Meeting of the AAO

November 16th-19th, 2003, Anaheim, California, USA

Top-Five on Epidemiology and Global Perspectives
Roy Wilson

• Anne Coleman ("Primary Open-Angle Glaucoma: The Developed World Perspective") emphasized that health disparities in racial and ethnic minority groups is a major issue in parts of the developed world—certainly in the USA—and glaucoma has both differential prevalence and prognosis according to race.
• Ravi Thomas ("Primary Open-Angle Glaucoma: The Developing World Perspective") introduced the concept of population attributable risk (PAR) and calculated that the treatment of ocular hypertension to prevent progression to glaucoma has a PAR% of only 8.5%, and that prevention of progression of early glaucoma has a PAR% of 20%. Interventions such as the provision of clean drinking water, sanitation, and immunization have a PAR% of more than 40%, are thought to represent a greater public health threat than ocular hypertension or early glaucoma, and are more likely to receive a greater proportion of the scarce health care resources available in developing countries.
• Robert Ritch ("Exfoliation Syndrome: Not Just a Scandinavian Disease") provided a comprehensive review of the prevalence of exfoliation syndrome in global areas outside Scandinavia, and noted that its presence is much more common than previously believed.
• David Friedman ("Shifting Paradigms in Our Understanding of the Primary Angle-Closure Glaucomas") then addressed primary angle-closure glaucoma, an entity which has received far less epidemiological attention than primary open-angle glaucoma, although it is just as important from a global perspective. Diagnostic technologies such as ultrasound biomicroscopy have provided information on pathogenic mechanisms and have influenced changes in long-standing classification and treatment paradigms associated with this condition.
• Ted Krupin ("The Baltimore Eye Survey: How It Has Impacted My Practice") concluded the session with a discussion on the clinical implications of the Baltimore Eye Survey, arguably the most significant epidemiological study of glaucoma to date. The importance of race (blacks versus whites), older age, and a family history of glaucoma as risk factors for glaucoma were emphasized.

CCT: Point-Counterpoint - Should Every Glaucoma Patient Have Pachymetry?
Robert Stamper

• Hans Goldmann was fully aware that major deviations in corneal thickness would cause inaccuracies in applanation tonometry. Most of the world ignored his statements in this regard.
• The refractive surgery movement rekindled the concern that a generation of patients would have glaucoma under-diagnosed because of laser thinned corneas.
• James Brandt was assigned the 'yes' side of the issue and pointed out that:
  • Thin corneas were shown by the Ocular Hypertension Treatment Study to be a proven risk factor for conversion from ocular hypertension to frank primary open angle glaucoma. Conversely, thick corneas are a low risk factor for conversion.
  • A recent study showed that thin corneas are a risk factor for the progression of early open angle glaucoma.
  • Thin corneas are associated with advanced open angle glaucoma and with normal tension glaucoma.
• George Cioffi was assigned the 'no' point of view and, while not really disagreeing with the points made by Brandt, only argued that:
  • Not all glaucoma patients need pachymetry. Examples include eyes with acute angle closure glaucoma or neovascular glaucoma.
  • The exact relationship between Goldmann applanation tonometry and central corneal thickness has not been satisfactorily worked out and no good conversion formula exists.
  • The Early Manifest Glaucoma Treatment study failed to establish a relationship between corneal thickness and the progression of early glaucoma, although small numbers and selection bias may have hidden a true relationship.
• In summary, it would seem that the measurement of central corneal thickness (pachymetry) is prudent in patients who are glaucoma suspects or who have established open angle glaucoma at least once during the course of their clinical evaluation. See also Editors' Selection.

Top-Nine on Surgery
Peng Khaw

• Steven Geddy reminded us that valved implants may reduce the bulk flow of aqueous, but do not eliminate leakage around the tube. It is particularly important to test for leakage around the tube, which will cause hypotony no matter how good a valve is.
• Jay Katz talked about repeating trabeculectomy after one failure. A particularly useful point for all of us was the use of balanced salt solution injected sub-conjunctivally to delineate scarring and make dissections easier and to prevent buttonholing.
• There was a lot of interest and a good reception when I reminded audience about the dramatic change which occurs in mitomycin blebs when large surface areas of treatment are used, combined with a fornix-based incision. This, together with an infusion during surgery, fornix-based conjunctival incision, with sutures buried in the cornea and new 'adjustable' scleral flap sutures, makes surgery a much more controllable procedure.
• Dale Heuer as usual gave us a highly amusing presentation about the pros and cons of glaucoma devices versus trabeculectomy. Apart from his extremely amusing 'Mickey Mouse' tube, he also presented some very useful data showing that the jury is still out on the use of tubes versus trabeculectomy for primary and repeat surgery.
• Mark Liebermann talked about the technique of needling and reminded us of the very useful tip that viscoelastic can be used to prevent reflux of 5FU into the tear film, reducing the corneal complications associated with this and also enhancing the effects of 5FU.
• Andrew Iwach went through bleb-related ocular infections and again reminded us of the very nice monemonic for our patients who have had antimetabolites, particularly with cystic blebs, RSVP. That is, Redness, Sensitivity to light, Visual acuity decline, Pain. These RSVP patients must return for specialist ophthalmic care straight away.
• For the section on glaucoma surgery and cataract surgery, Richard Mckool reminded us that using the infusion to 78 cm can raise IOP to up to 60 mmHg, and that to maintain an AC at a lower height, two incisions may be needed. Mckool also gave us the excellent tip that it might be useful to use a viscoelastic to prevent lens material from going into a bleb and causing long-term inflammation.
• Sam Masket talked about IOLs and reminded us that it would be best not to sulcus fixate any lenses if at all possible, and also to avoid silicone lenses, particularly where the capsule is contractile such as in pseudo exfoliation.
• Finally, Jim Tsai reminded us that studies have shown very prolonged subclinical inflammation after phacoemulsification, and this must be taken into consideration when managing wound healing and combining filtration surgery with cataract surgery. He also stressed that new agents are becoming available.

Three Reminders on Science
Paul Kaufman

• None of the current techniques for measuring optic nerve or ocular blood flow are of clinical relevance for making decisions or understanding the pathophysiology of glaucoma - Minckler.
• There is no current clinically proven neuroprotective therapy for glaucoma other than reducing intraocular pressure - Girkin.
• While certain gene/promoter mutations have been linked to the development or progression of certain forms of glaucoma, genetic testing presently adds little value to glaucoma therapeutic decision-making. However, lessons from other systemic diseases teach us that all this could change as we learn more about the pathophysiology and therapy of glaucoma - Allingham.

Issue 5-3

Table of Contents Editor's Selection

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