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APVRSSHOWDAILY | Jul 31 – Aug 2, 2015 | Sydney, Australia
Controversies and Developments in... by Claire Noonan
The incidence of retinal vein occlusion (RVO) is increasing. It is the second most prevalent cause of retinal vascular disease after diabetic retinopathy. Therapeutic options for patients with RVO each have their pros and cons. At the APVRS congress today speakers at the symposium on RVO and other retinal vasculopathies discussed the latest evidence and new directions. The chief causative factors of RVO are age and cardiovascular risk, though recently dehydration as a cause has been postulated. With today’s trends of intense exercise and intermittent fasting diets, dehydration can leave the blood more viscous, leading to a higher likelihood of venous occlusion, though evidence is scant so far, says Sobha Sivaprasad, MBBS, MS, DM, FRCS, FRCOphth, Professor and Consultant Ophthalmologist at Moorfield’s Eye Hospital and Kings College Hospital, United Kingdom. ‘Since the Royal College guidelines for managing RVO came out ten years ago, the protocol has evolved from extensive testing for all possible underlying causes, to just the basic tests: blood pressure, blood sugar levels, ESR and FBC, as the majority of cases (around 99%) are caused by arteriosclerosis,” explained Prof. Sivaprasad. If cardiovascular risk factors are not present, then the rarer causes such as a thrombophilia or an inflammatory condition, can be considered. Another major change is that aspirin is no longer routinely given as Prof. Sivaprasad explains evidence has shown ‘it does not prevent contralateral or recurrent RVO’. The use of imaging in diagnosis and classification of RVO was also discussed by Prof. Sivaprasad. In a study by
Kaines and colleagues, some cases that appeared to be non-ischemic on a 7-field image had clear areas of non perfusion when viewed with wide field angiography. The usefulness of wide field imaging was further discussed by Ian McAllister, MBBS W.Aust., FRACS, FRACO, Professor of Ophthalmology and Director, Clinical Services, Centre for Ophthalmology and Visual Science (incorporating Lions Eye Institute), The University of Western Australia, who explored the features of different imaging modalities and the benefits of each with regard to visualizing aspects of RVO. There has been ongoing and exciting developments in imaging, leading up to SPECTRALIS, which, as Prof. McAllister noted, is a multimodal system and one whose images we are still learning how to read. A key feature in RVO is macular edema, the leading cause of visual loss in RVO. Also, VEGF is upregulated in the ischemic retina. Prof. McAllister reminded the congress that increased VEGF brings with it ‘devastating consequences’. He commented that Anti-VEGF seems to be useful in decreasing the incidence of capillary non-perfusion, as found by Campochiaro and colleagues (Ophthalmology 2012). It can also increase visual acuity. Findings were consistent across study arms: when the patients who started on placebo were later given anti VEGF the same good effect was observed. Prof. McAllister called for further studies to see if anti-VEGF administration can prevent perfused cases from progressing to a non-perfused state. ‘We need more data to understand the protective effect’, he concluded.
RVO Hyung Chan Kim, M.D., professor and chairman of the Department of Ophthalmology at KonKuk University Medical Centre, South Korea, outlined the indications for steroid treatment, such as those patients in whom antiVEGF is contraindicated, or those who are non-responders to anti-VEGF. Due to the short half life of dexamethasone injections, he explained that an implant drug delivery system is invaluable for these patients.
“Sequential or combination treatments for RVO is an option the cost of treatments are prohibitive in some countries, necessitating clear evidence for their use,” said Ian Wong, FRCOphth, FRCS (Edinburgh), FHKAM (Oph), FCOphthHK, M.Med (Singapore), MBBS(HKU), Clinical Assistant Professor, University of Hong Kong. Discussing the option of starting a patient on antiVEGF for the rapid onset benefit, followed by a dexamethasone implant to give improved visual acuity and better resolution of macular edema: “Future studies should look at the ideal interval between the treatment steps and assess any difference in response between ischemic and non-ischemic RVO cases,” said Dr. Wong. On the other hand, Victor Chong, M.D., FRCS, FRCOphth, clinical senior lecturer at the University of Oxford Eye Hospital, mentioned novel treatments targeting RVO that may ease the treatment burden, such as panretinal photocoagulation and laser induced venous bypass. He gave the congress a message of hope: ‘the ischemic retina can indeed recanalize’.