Eyeworld

EW CORNEA 24 July 2011 I n the future, it may be possible that the cure for pterygium isn't total surgical excision. A new report hints that some concoction of bevacizumab (Avastin, Genentech, South San Francisco, Calif.) could be injected and reduce the size of pterygium. The research, published online in Cornea in September 2010, found that intralesional bevacizumab in- jection reduces the size of pterygium and is well tolerated. However, there was no clinically significant impact on the reduction in pterygium size. The fact that bevacizumab worked to reduce pterygium size still holds promise. Current methods to excise pterygium surgically and prevent re- currence have side effects, including punctate epitheliopathy, bacterial superinfection, delayed onset sclera melting, and IOP rise. Given that bevacizumab was both effective in reducing pterygium size and safe, it may just be a matter of tweaking the number of injec- tions to cause an even greater size reduction. "Repeated injection of beva- cizumab (to decrease the pterygium size more efficiently) or its adjuvant role before or during surgical re- moval of pterygium may help to ad- dress its clinical significance in future studies," according to the re- port, co-authored by Mehrdad Mohammadpour, M.D., Eye Re- search Center, Farabi Eye Hospital, Tehran University of Medical Sci- ences, Iran. A decrease in size Pterygium was analyzed in 17 pa- tients (14 with primary pterygium and three with recurrent pterygium). Patients received intralesional injec- tions of bevacizumab (2.5 mg/0.1 mL). Injection occurred at the base of the pterygium with a 25-gauge needle. All patients received a single injection, except two primary cases and one recurrent case, which re- ceived a second injection. Prior to injection, mean lesion size was 17.2%+/–4.3% of the corneal surface. Lesions reduced to 15.1%+/–4.3% at 1 week after injec- tion, 13.4%+/–4.0% at 1 month, and 14.1%+/–4.4% at 3 months. Lesion size was determined with the help of digital photographs and image analysis software. The mean percentage decrease was 3.97%+/–3.84% in primary pterygium cases. The decrease in size before injection and after at all time periods was statistically significant. Notably, recurrent pterygium cases did experience lesion progres- sion (by 1.11%+/–0.450%). Also, visual acuity did not change signifi- cantly in any patient after the injec- tions. "It is postulated that for control of corneal neovascularization, higher doses of bevacizumab than the classic 2.5-mg dosage given in intravitreal injections may be needed for subconjunctival injec- tions," Dr. Mohammadpour re- ported. Pterygia "are known to depend on neovascularization," Dr. Mohammadpour noted. Mechanism of action Bevacizumab likely reduces the size of pterygium due to its anti-VEGF action. "Several active angiogenic and epithelial growth factors such as basic fibroblast growth factor, he- parin-binding epidermal growth fac- tor, connective tissue growth factor, and vascular endothelial growth fac- tor (VEGF) have been shown to be significantly increased in pterygium, suggesting that growth factors may be involved directly or indirectly in its pathogenesis," Dr. Mohammadpour reported. "How- ever, the most prominent of these factors is VEGF, which is the main target of many current antiangio- genic therapies. Bevacizumab is a monoclonal antibody to VEGF A that binds to both VEGF receptors VEGFR2 and VEGFR1 and inhibits both receptors." Already, research has suggested bevacizumab is effective for the treatment of corneal neovasculariza- tion, Dr. Mohammadpour noted. Literature about the impact of bevacizumab on pterygium, how- ever, has been mixed. One study found anti-VEGF treatment con- trolled pterygium inflammation, while another found bevacizumab had no impact on corneal vessel density in recurrent pterygia. In an- other study, topical bevacizumab was used to treat impending recur- rent pterygium with success. "The promising point of view is that in these studies, there was no reported adverse effect for beva- cizumab," Dr. Mohammadpour con- cluded. "The important question is to quantify the therapeutic concen- trations of such antibodies in the cornea." Francis S. Mah, M.D., co-med- ical director, Charles T. Campbell Ophthalmic Microbiology Labora- tory, University of Pittsburgh School of Medicine, said that other research institutions have looked at anti- VEGF treatment for pterygium re- moval, calling it a "hot topic" for surgeons. "We don't know how to best apply the medication," Dr. Mah said. "We also don't know the best dosage." Dr. Mah believes more research needs to be done to study the short- term effects of drug use, such as po- tential toxicity. "This is a hopeful avenue with a lot of unanswered questions," Dr. Mah said. EW Editors' note: Dr. Mah has no financial interests related to his comments. Dr. Mohammadpour has no financial inter- ests related to this study. Contact information Mah: 412-647-2211, mahfs@upmc.edu Mohammadpour: mohammadpour@yahoo.com by Matt Young EyeWorld Contributing Editor Study finds new possible treatment for pterygium A patient is injected with bevacizumab. A recent study indicates that these injections may be a possible treatment for pterygium Source: María H. Berrocal, M.D. iPS cells may reverse gyrate atrophy S tem-cell technology has successfully been used to correct a genetic defect present in gyrate atrophy, a rare eye disease that affects reti- nal pigment epithelium (RPE) cells causing progressive vision loss. In a study published in the June 2011 issue of Stem Cells, Jason Meyer, Ph.D., assistant professor of biology, School of Science, Indiana Univer- sity-Purdue University, Indianapolis, and colleagues report on developing a technology to generate induced pluripotent stem cells from a human patient with the disorder. "When we generate iPS cells, correct the gene defect that is responsi- ble for this disease, and guide these stem cells to become RPE cells, these RPE cells functioned normally," said Dr. Meyer in a press release. "This is exciting because it demonstrates we can fix something that is out of order. It also supports our belief that in the future, one might be able to use this approach for replacement of cells lost or malfunctioning due to other more common diseases of the retina." Researchers hope that use of the cells can avoid transplant rejection, and may be able to restore vision once the gene defect responsible for the disorder is corrected.

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