February 1, 2010
Kaiser Study Compares AMD Drugs; Global Study On RVO; Vision And Falls In Elders
Ophthalmology February highlights
This month's Ophthalmology, the journal of the American Academy of Ophthalmology, includes results from a large Kaiser Permanente study of age-related macular degeneration (AMD) treatments, the first global report on retinal vein occlusion, and new recommendations to help elders with vision loss avoid falls.Kaiser Study Compares Effectiveness of Two AMD Drugs
A Kaiser Permanente Southern California study compared two very similar medications"“ ranibizumab and bevacizumab"“used to treat "wet" AMD and found the two equally effective at halting vision loss. Because many Americans will soon be 65 or older and AMD incidence rises sharply with age, the disease is becoming an urgent concern for the healthcare system. Donald S. Fong, MD, MPH, and his Kaiser colleagues followed 324 newly-diagnosed AMD patients treated with bevacizumab and 128 treated with ranibizumab between 2005 and 2008. Visual acuity improved and stabilized in both patient groups: the proportion of patients who had 20/40 vision or better increased from 13.6 percent at baseline to 22.9 percent at 12 month follow-up in bevacizumab-treated patients and from 11.7 percent to 25.0 percent in ranibizumab-treated patients.
Ranibizumab (Lucentis) was specifically developed to treat the wet (neovascular) form of AMD and received U.S. Food and Drug Administration (FDA) approval in 2006; bevacizumab (Avastin) was originally approved by the FDA as a cancer treatment and was used "off label" by ophthalmologists before Lucentis became available. Since Avastin appears to be beneficial and costs significantly less per dose than Lucentis, ophthalmologists continue to use it. Several comparative studies of the two drugs are underway, in relation to efficacy, safety, treatment protocols and cost-effectiveness. Results of the Comparisons of Age-Related Macular Degeneration Treatments Trials (CATT), a randomized clinical trial involving 44 centers across the U.S. and funded by the National Eye Institute, are likely to be particularly important.
"Some physicians are concerned about the effectiveness of Avastin, but our data did not seem to show any difference," Dr. Fong said. "Our results illustrate real-world use of AMD treatments: at the time of our study, there was no universal agreement within our 11 centers on optimal protocols, so treatment intervals and the drug selected for use depended on doctor-patient preference," he added.
First Report on Worldwide Prevalence of Retinal Vein Occlusion
Ophthalmologists recognize retinal vein occlusion (RVO), commonly called "eye stroke," as a serious disease and significant cause of blindness. Surprisingly, the magnitude of the problem had been unclear prior to this first report on worldwide RVO prevalence by the International Eye Disease Consortium (IEDC). Based on data from 15 major population studies in the United States, Europe, Asia and Australia, the IEDC estimates that globally, 16.4 million adults are affected by RVO. For comparison, more than 131 million adults with diabetes worldwide either have diabetic retinopathy or are at risk of developing this potentially blinding disease, according to a 2005 World Health Organization report.
In central and branch retinal vein occlusion (CRVO and BRVO), vision impairment and eye damage occur when the vein becomes blocked, usually by a blood clot. This leads to reduced blood flow, hemorrhage and/or swelling in the retina, the light-sensitive tissue at the back of the eye that receives images and relays them to the optic nerve. An estimated 13.9 million people worldwide are affected by BRVO, and 2.5 million by CRVO, the IEDC report found. Prevalence is similar in men and women and increases with age, probably because of age-related increases in arteriosclerosis, hypertension and glaucoma or elevated intraocular pressure. Although BRVO prevalence appears to be highest in Asians and Hispanics and lowest in whites, the authors say this may reflect varying methodologies or definitions among reviewed studies rather than true ethnic differences.
"We need to understand how hypertension and other cardiovascular risk factors impact BRVO and CRVO, and how glaucoma impacts CRVO, in various ethnic groups and populations so that appropriate preventive and treatment strategies can be designed," said Tien Y. Wong, MD., PhD, lead investigator for the IEDC.
Central and Side Vision Factor into Older Americans' Risk of Falling
Each year, falls occur in 35 to 40 percent of people age 65 and older who are generally healthy and living independently. About half of all falls result in injury, and up to 18 percent of these injuries require medical care. It is well known that people with reduced central vision"“the ability to see clearly in front of them"“are more likely to fall. A new report from the Los Angeles Latino Eye Study (LALES) is the first to show the independent effects of impairment of central (CVI) and of peripheral vision (PVI).
CVI and PVI were measured for more than 3,200 LALES participants at the time each person joined the study, between 2000 and 2003. In participant reports gathered between 2004 and 2008, 19 percent reported falls and 10 percent falls with injury within the previous 12 months. The proportion of falls and falls with injury increased with the severity of CVI and PVI, suggesting cause-and-effect relationships. People with CVI were at 2.8 times' higher risk for falls with injury than those with no visual impairment, and PVI increased the risk 1.4 times. Seventy percent of those with CVI also had PVI.
"The data strongly suggest that treating central vision alone may be insufficient to help prevent falls and falls with injury, and that older patients should also be screened and treated for PVI," said lead researcher Rohit Varma, MD, MPH. "Also, we recommend advising patients aged 60 and older on their increased fall risk and the need to take extra precautions. Finally, since persons in our study with normal vision also experienced falls and related injuries, research is needed on other causes of this problem."
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