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Wednesday / June 29.
HomemiophthalmologyEye on WGC 2011: Global Findings, Local Insights

Eye on WGC 2011: Global Findings, Local Insights

This year, the 4th World Glaucoma Congress (WGC) – the largest glaucoma meeting to date – was held from 29 June to 2 July 2011. Over 2,000 ophthalmology practitioners and researchers from around the world gathered in Paris, or La Ville Lumière – The City of Light – as it is affectionately named. In line with its support for continuing medical education, Pfizer Ophthalmics invited four ophthalmologists from Australia to attend WGC 2011 as conference reporters.This article contains selected excerpts from the team’s reports, covering a range of topics in glaucoma research and practice.

A wide array of topics were discussed at WGC through a variety of educational events including symposia, case management grand rounds, surgical video presentations, skills transfer courses and scientific paper presentations selected by competition from over 800 submitted abstracts.

In focus: Glaucoma Grand Rounds

Case One
Espino Garcia, Spain, presented a case of Posner Schlossman Syndrome in a patient with recurrent episodes of severe pressure spikes, subsequently found to have cytomegalovirus (CMV) retinitis. A key reminder to the audience was to always dilate the pupil to exclude retinal or vitreous inflammation. While the condition is often self-limiting and the trabeculitis responds to steroids, systemic treatment with antiviral therapy may be warranted if the posterior segment is involved. Toxoplasmosis can present in a similar manner and, hence, be missed. Viruses – particularly CMV – may be implicated so an aqueous tap can be performed in atypical cases. In fact, it is likely that this condition is, in most cases, virally induced.

Case Two
The second case was of a young boy with a severe firecracker burn to his only eye with destruction to the conjunctiva and cornea, akin to that seen with an alkali burn. The eye was gradually rehabilitated with grafting techniques and penetrating keratoplasty, but the latter failed twice. A Boston keratoprosthesis was successfully used to provide vision as good as 6/30. However, the prosthesis prevented accurate intraocular pressure (IOP) measurement. He presented a year later with severe peripheral field loss. Digital IOP was the only measure, although an audience member suggested that phosphene IOP could be a guide. He underwent a successful Ahmed tube insertion, and has maintained his residual field since then. While the surgery was very successful, the main message from this case was that all severe ocular surface injuries are expected to predispose to secondary glaucoma, and should be monitored very closely for this.

Much can be achieved by interest and empathy alongside good clinical care and, where appropriate, timely referral to rehabilitation services…

Angle-closure Glaucoma: What Does the Evidence Show?

This interesting session on angle-closure glaucoma (ACG) reviewed the epidemiology and classification of angle closure and discussed the underlying mechanisms, including the role of the crystalline lens. Gus Gazzard, United Kingdom, provided a helpful overview of the current terminology of angle closure. Much of the published work over the past decades has been confused by differences in terminology and clinical usage.

The prevalence of ACG in Caucasian and Chinese populations differs due to both definitional differences between studies and underlying genetic factors. The estimated population prevalence in European-derived populations is 0.50 per cent in those older than 40 years of age, with approximately 75 per cent female and up to 50 per cent with chronic asymptomatic disease. The prevalence in Chinese and Asian populations ranges from 0.5 per cent to 3 per cent.

Predictive risk factors for angle closure were discussed in detail. Historically, static measures have been used, which are not representative of the dynamic physiological status of the eye. The epidemiology of new static measures, such as iris curvature, thickness and volume, lens vault, and anterior chamber area and volume, is being actively researched. The epidemiology of dynamic physiological factors, such as iridotrabecular contact on ultrasound biomicroscopy (UBM), is also undergoing extensive study. However, careful consideration is needed regarding which assessment modality is considered the reference standard in defining anatomical risk factors for glaucomatous visual loss and the need for treatment.

Patient Needs in Glaucoma

The final session of the WGC featured some interesting presentations focusing on patient and population issues. While dealing with glaucoma as a clinical problem on a daily basis, we may lose sight of what this disease means to the individual’s quality of life.

Pradeep Ramulu from the Wilmer Eye institute, USA, addressed quality-of-life issues in glaucoma patients, noting that this was largely affected by a combination of ability and attitude. It is crucial to view management from a patient’s perspective, noting what they are able to do and how things may change, particularly in regard to their main concerns of mobility, reading and vision in extremes of lighting. Degrees of field loss are related to these activities – every 5dB decrease in visual field mean deviation is associated with a 10 per cent decrease in reading speed, in addition to a greater variability in reading speed over the short term. With respect to physical activity, a 5dB decrease in mean deviation was shown to result in a 9 per cent decrease in activity, approximately equal to the effects of arthritis; a 15dB decrease equated to a 25 per cent decrease in activity.

Our management of glaucoma should not begin and end with the prescription pad or the scalpel. Much can be achieved by interest and empathy alongside good clinical care and, where appropriate, timely referral to rehabilitation services.

Following the Ocular Hypertension Treatment Study (OHTS), the concept of risk calculation for glaucoma was developed. This has since been refined by combining the OHTS data with the European Glaucoma Prevention Study (EGPS) data. This may be helpful in our practices but, as Felipe Medeiros pointed out in his presentation, these calculators estimate the risk of developing the earliest signs of glaucoma. What may be more useful is the ability to determine which of our patients are at risk of developing disabilities resulting from glaucomatous visual loss.

Primary Angle-closure Glaucoma Without Cataract

A number of clinical scenarios exist when considering the role of surgery in primary angle-closure glaucoma (PACG). It is believed the size and position of the lens play a major role in the pathogenesis of PACG; with ageing, there is a progressive increase in the thickness of the lens and a relatively more anterior lens position. This is accentuated in hyperopic eyes. Lens extraction with posterior chamber intraocular lens (IOL) placement with subsequent deepening of the anterior chamber results in a reduction in angle crowding and the relief of relative pupil block.1

The risk of requiring cataract surgery following trabeculectomy is reported to be between 20 per cent and 52 per cent, up to seven years postoperatively. In the Collaborative Normal Tension Glaucoma Study, the incidence of cataract in the treated group (38 per cent) was significantly higher than in the control group (14 per cent, p<0.001).2 Among treated subjects developing cataract, nearly three-quarters had undergone filtration surgery, whereas only 29 per cent were on medical therapy. Results from the Collaborative Initial Glaucoma Treatment Study were similar.3

The literature report 10 to 61 per cent of trabeculectomies failing at 12 to 36 months post-cataract surgery.4 In a case-control study with two-year follow up, it was found that 24 per cent of trabeculectomies that underwent cataract extraction failed, compared with 7 per cent failure rate in those that did not have cataract surgery.5

The Eye on WGC 2011 editorial team comprised of Dr. Guy D’Mellow, Terrace Eye Centre Brisbane, Qld; Dr. Antonio Giubilato, Lions Eye Institute, Nedlands, WA; Dr. Tim Roberts, Royal North Shore Hospital, Sydney, NSW and Professor Stuart Graham, Eye Associates, Sydney, NSW.

This article includes information contained in selected reports from WGC 2011. To obtain full reports or for information on how to receive reports from Eye on WGC, please send your request to joel.ho@pfizer.com

References
1.Weinreb RN and Friedman DS (Editors). Angle Closure and Angle Closure Glaucoma: Reports and Consensus Statements of the 3rd Global AIGS Consensus Meeting on Angle Closure Glaucoma. Kugler Publications, The Hague, The Netherlands. 2006
2. Collaborative Normal-Tension Glaucoma Study Group. Am J Ophthalmol 1998; 126(4): 487-497
3. Musch DC et al. Arch Ophthalmol 2006; 124(2): 1694-1700
4. Mathew RG, Murdoch IE. Br J Ophthalmol 2011; Jan 8 [Epub ahead of print]
5. Swamynathan K et al. Ophthalmology 2004; 111(4): 674-678

Disclaimer
This material is provided for educational purposes. Whilst it contains excerpts from factual reports from the WGC 2011 congress, it is neither supported nor endorsed by the World Glaucoma Congress. Not all products and devices discussed are registered for use in Australia by the Therapeutic Goods Administration (TGA) or have indications approved by the TGA. Please refer to the published, Australian-approved Product Information before prescribing any product mentioned in this report. The opinions expressed herein are those of the Eye on WGC editorial team. Although they do not necessarily reflect those of the sponsor or publisher, both parties have made every effort to ensure that the authors’ opinions are accurate, fair, balanced and consistent with the general body of information. Pfizer Australia Pty Limited, ABN 50 008 422 348, 38-42 Wharf Road, West Ryde, NSW 2114. www.pfizer.com.au

Current recommended classification
of primary angle closure:

Primary angle closure suspect
• Unable to view the posterior trabecular meshwork for at least 180°
• Intraocular pressure (IOP) < 95 per cent of the population
• No evidence of optic disc or field change
Primary angle closure (PAC)
• Iridotrabecular contact
• Evidence of secondary effect (peripheral anterior synechiae and raised IOP)
• No optic disc or field damage
Primary angle-closure glaucoma
• PAC plus
• Disc and/or field damage as defined in open-angle glaucoma

What should we ask glaucoma patients about their quality of life?

Four simple questions, as suggested by Ramulu:
1. Who lives with you?
2. Are you still working?
3. Are you still driving?
4. In what ways does glaucoma affect you?

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