The annual meeting of the Association for Research in Vision and Ophthalmology (ARVO) was recently held in Fort Lauderdale, Florida, U.S. from 3 to 7 May. This global forum brought together approximately 10,000 vision researchers and practitioners to explore cutting-edge research in vision and eye disease.
As part of its commitment to continuing medical education, Pfizer Ophthalmics invited four ophthalmologists from Australia to attend ARVO 2009 as conference reporters.
The following are excerpts from their daily reports, detailing the highlights from the meeting:
Professor Jonathan Crowston
Prof. of Ophthalmology, Centre for Eye Research, University of Melbourne, Vic
Optic Nerve Damage in Glaucoma
The ARVO glaucoma mini-symposium this year addressed the question ‘What damages retinal ganglion cells in glaucoma?’ Dr. Claude Burgoyne from Portland, Oregon, described a “biomechanical paradigm” for optic nerve injury.
This paradigm considers a number of factors that contribute to axonal injury in glaucoma including connective tissue biomechanics, the cellular response to stress, the vascular supply of the optic nerve head and the supply of nutrients, as well as axonal transport.
Multiple processes lead to retinal ganglion cell death in glaucoma. Many of these become more apparent as the optic nerve ages and explain the rapid rise in glaucoma prevalence that accompanies increasing age. Systematic approaches that investigate changes in the ageing optic nerve, in particular those that increase the vulnerability of the ageing optic nerve to injury, have the potential to uncover new therapeutic targets that protect retinal ganglion cells and prevent vision loss in glaucoma.
Risk Factors for Glaucoma: What Lies Beyond Elevated IOP?
The measurement of IOP in isolation is inadequate as a screening tool for glaucoma as a large proportion of patients does not develop elevated IOP. Alternative risk factors also contribute to optic nerve damage in glaucoma.
However the question remains as to whether these are truly independent of IOP. Even at normal levels of IOP, significant stresses are present in the optic nerve head and retina, and IOP lowering has been shown to slow progression. Nonetheless clinicians should also look for alternative risk factors that may contribute to disease progression in glaucoma patients.
Professor Paul Mitchell
Prof. of Ophthalmology, University of Sydney, Westmead Hospital, NSW
Diabetic Retinopathy: Managing a Global Epidemic
Dr. Arup Das, University of New Mexico, U.S., discussed molecular mechanisms in diabetic retinopathy, a multi-factorial disease characterised by changes in the blood-retinal barrier, and later formation of new vessels.
Dr. Das also discussed the concept of ‘metabolic memory’, whereby prolonged periods of tight glycaemic control early in the course of diabetes are associated with a persistent reduced incidence or progression of diabetic retinopathy and other complications that remain long after the period of tight control.
Dr. Mark Blumenkranz, Stanford University, U.S., pointed out that newer lasers are becoming more like drugs, with an ability to better modulate dose.
Dr. Aiello outlined the promise of a range of new therapeutic areas, from intravitreal anti-vascular endothelial growth factor (VEGF) treatments to medically-induced vitreolysis, and the potential even for future topical multi-targeted therapies.
He concluded by discussing advances in the search for new biomarkers of increased risk for diabetic retinopathy. One finding – that increased retinal blood flow was a biomarker of increased retinopathy risk – was documented in his research.
AMD: Risk Factors and Implications
Two main genetic risk markers (the complement factor H, or ‘CFH’, and the LOC 387715 or ‘ARMS2′ gene variants) have been recently confirmed to substantially increase a person’s risk of developing AMD.
However, increased dietary consumption of foods relatively high in zinc and antioxidants, such lutein, in people with the CFH gene, was shown to reduce this genetic risk close to that seen in people without the CFH risk genotype.
Somewhat similar findings were also reported for the benefits of micronutrients in people with the ARMS2 risk genotype. The implication is that patients who have a strong family history of AMD and have signs indicating a high risk of progression to vision-threatening late AMD may be able to ‘eat away’ their genetic risk by modifying their diet.
Dr. John Males
Consultant Ophthalmologist, Sydney Eye Hospital, NSW
Nanotechnology: The Way of the Future in Ophthalmology?
Dr. Lowe of Thomas Jefferson University discussed ‘nanogels’, compounds which allow molecules to penetrate barriers that they would normally not be able to, such as the cornea and the blood ocular barrier.
Dr. Parviz, from the University of Washington, discussed his work with ‘smart’ contact lenses. He foresees a future where contact lenses will be able to monitor various parameters such as intraocular pressure, tear osmolarity, glucose and signs of infection.
Nanotechnology presents potentially exciting opportunities in ophthalmology. The capability of these technologies, whilst in most cases still unproven, appears widespread. The nanotechnologies presented, suggest potential applications in the diagnosis and monitoring of eye disease. Targeting specific areas of the eye with drug therapy to both improve efficacy and lower overall treatment dose required is also promising, although still very much in its infancy.
Ocular Surface Reconstruction: Update on the Use of Stem Cells
Those who suffer the misfortune of severe limbal stem cell failure, most commonly occurring following chemical injuries and conditions such as Stevens-Johnson Syndrome, face difficulties in being managed clinically. Limbal stem cell failure is one of the most challenging ocular surface problems to treat.
The traditional treatment of direct transplantation of limbal stem cells from the healthy eye exposes it to the risk of stem cell failure as well. Culturing stem cells sourced from the patient in the laboratory holds promise in the treatment of this challenging condition.
Whilst the visual results of limbal transplantation are not comparable to other areas of ophthalmic surgery, they are still able to significantly improve the quality-of-life for individuals in difficult circumstances.
Associate Professor Anthony Kwan
Assoc. Prof. of Ophthalmology, University of Queensland, Qld
Retinal Diseases: Novel Insights into Imaging and Functional Techniques
New modalities of retinal imaging techniques have been developed in recent years that allow detailed analysis of retinal structure in the normal and diseased eye. With these techniques, damaged retinal structures can be identified and followed up during disease progression and treatment.
Structure-function relationship has been the basis of investigating treatment of retinal diseases in animal models. Hence these new imaging technologies represent a timely approach to objective assessment of the diseased retina and treatment efficacy in humans.
This session highlighted the importance of the development of new retinal imaging techniques in assessing retinal diseases and their use in monitoring disease processes and treatment. It is clear from these presentations that we can now study in detail the close relationship between structural and visual function changes in the retina.
With the development of high resolution optical coherence tomography and adaptive optics in particular, the relationship between retinal structure and visual function will be even clearer in the future.
Intravitreal Injections: Practical Insights
Impact of injection site on infective endophthalmitis: with the increasing number of repeated intravitreal injections in patients who are receiving anti-vascular endothelial growth factor therapy, one is expected to vary the injection site for each patient.
In this presentation, Dr. Roth’s group from New Brunswick and Miami looked at the incidence of infective endophthalmitis in relation to the injection site. This is a retrospective observational case series. A total of 10,834 injections were given in 1,302 eyes of 1,017 patients. The most common site of injection was the supero-temporal area.
A total of five eyes developed presumed infective endophthalmitis with an overall incidence of 0.046 per cent, and two eyes were culture-positive (overall incidence of 0.018 per cent).
An interesting observation was that, in four out of five eyes, the injection site was inferior. The risk ratio associated with inferior injection site was 17.0 (p<0.011; 95 per cent CI: 1.9 to >100). Hence, it appears that an inferior injection site is associated with an increased risk of infective endophthalmitis.
This article contains reports from data presented at an international meeting. Please refer to the published Approved Product Information (PI) before prescribing any product mentioned in this article. Although the opinions expressed herein 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 Ltd, ABN 50 008 422 348, 38-42 Wharf Road, West Ryde, NSW 2114, Australia. Phone: (AUS) 02 9850 3333. Fax: (AUS) 02 9850 3146 www.pfizer.com.au