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Anti-angiogenesis Therapy Brings Hope to
With the advancement in biotechnology, anti-angiogenesis, as a specific target treatment, becomes feasible for treating CNV. The drug is injected intravitreally and it will block the VEGF, a growth factor, which is essential for the abnormal vessel development and proliferation in AMD and high myopia. This therapy initiates a new treatment direction for macular diseases because of its specificity and local action. Avastin, as an anti-angiogenesis approved to treat colon cancer, has been used by the Chinese University of Hong Kong (CUHK) for the treatment of wet AMD and high myopia by intravitreal injections. Over 200 intravitreal injection treatments have been delivered since November 2005 in managing more than 80 patients. The early data have been promising that Avastin not only stopped the progression of neovascularization in these patients, but also resulted in visual improvement in many of them, which were usually not possible in the past by using other alternatives. In the AMD group, the mean improvement in visual acuity at 3-month follow-up was 1.5 lines, in comparisons with a drop in 1.2 lines with photodynamic therapy and 2.0 lines with placebo in another study. In the high myopia group, the mean improvement in visual acuity at 3 months was 3.5 lines, whereas the patients receiving photodynamic therapy, in another study, maintained the same level of visual acuity and dropped by 1.0 line with placebo at 3-month follow-up. ¡§The results are encouraging. We have more patients experiencing visual gain when compared to other conventional treatment methods. The new treatment may create a paradigm shift in the management of CNV due to various causes,¡¨ remarked by Professor Wai-man Chan, Professor of the Department of Ophthalmology and Visual Sciences, the CUHK. Professor Dennis Shun-chiu Lam, Chairman of the Department of Ophthalmology and Visual Sciences, the CUHK commented that, ¡§a three-injection regimen is adequate to stop the CNV growth completely in high myopia with a satisfying 3.5 lines improvements at the 3-month follow-up. The effects have been sustained up at the 6-month follow-up and patients did not require further treatment. In AMD, the optimal number of injections required needs further work on analysis and trials.¡¨ Nevertheless, Avastin is not a magic treatment and it cannot restore vision already permanently lost,¡¨ Professor Lam cautioned. Avastin is an anti-angiogenesis drug and its off-label use in treating eye with CNV started in 2005 in the United States for AMD. The drug is injected intravitreally of a tiny amount in a monthly basis. The pharmacological effect is tissue-targeted at CNV and the local administration route minimizes the risk of having systemic side effects. Researches focus on the best injection regimen to achieve an entire control of the diseases. Professor Chan warned that with an ageing population and a rising prevalence of high myopia in Hong Kong, the number of patients suffering from macular diseases would be on the rise. ¡§AMD is the leading cause of blindness in elderly over 50 in western countries and unfortunately there are signs that Hong Kong is following the footsteps of western countries,¡¨ Professor Chan further remarked. ¡§Age is the most important factor and has been shown to be strongly linked to AMD. Other risk factors are cigarette smoking, diet with saturated fat and cholesterol, excessive sunlight exposure, family member with AMD, genetic and one eye already suffered from AMD,¡¨ Professor Chan continued. High myopia is the seventh leading cause of blindness in the US. As the estimated percentage of high myopia in the general population in Hong Kong is 4%, compared to only 2% in the US, Professor Lam envisaged that the local situation of high myopia related CNV would be worse than that of the US. There is also a higher possibility of macular diseases in the younger generation in Hong Kong, since a recent study by the CUHK revealed that 6% of secondary students in Hong Kong are suffering from high myopia. Professor Lam pointed out that once the photosensitive retinal cells in the macular region have been damaged, the vision is, in general, not recoverable. ¡§Early detection and treatment is crucial for keeping the vision.¡¨ Professor Lam recommended people over the age of 50 or with higher risk for AMD, as well as those suffering from high myopia, to do self-check daily with an Amsler chart and to have regular check-up by eye doctor.
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