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kanupriya misha darrad, Nirodhini Narendran, Yit C Yang, Sam Lee; Correlation between Age of onset and number of ranibizumab injections required in patients with wet Age related Macular Degeneration. Invest. Ophthalmol. Vis. Sci. 2014;55(13):3874.
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The role of the vitreous in health and disease has been brought into question in recent years. Recent work suggests that integrity of the vitreoretinal interface may influence the number of injections of ranibizumab required in wet Age related Macular Degeneration (AMD) treatment, with the presence of a posterior vitreous detachment being correlated with reduced injection frequency. Since posterior vitreous detachment is an aging phenomenon we hypothesised that age at presentation has an influence on the number of ranibizumab injections required to treat wet AMD.
A retrospective analysis of all patients commencing ranibizumab therapy for wet AMD between December 2009 and May 2011 and completing 2 years’ follow up was undertaken. The age of the patient at the start of treatment and the number of injections in the first and second year were recorded. Only individuals with choroidal neovascular membrane secondary to age related wet AMD were included and where presentation was bilateral, the eye with worse visual acuity was used for analysis purposes. Mean number of injections in first and second years were determined for each of four groups divided according to quartile ranges of age. Correlation coefficient between age and number of injections over two years was analysed with data from entire group.
357 subjects were included with an age range of 47 to 97. The cohort was split into 4 equal groups with mean ages of 68.43 ± 5.62 (range 47 to 74), 77.03 ± 1.81 (range 74 to 80), 82.29 ± 1.18 (range 80-85) and 88.11 ± 2.73 (range 85 to 97) respectively. In each of these groups, injection numbers in the first year were 6.94, 6.34, 6.17, 6.24 and in the second year were 4.54, 3.62, 3.54, 3.28. The correlation coefficient of age against number of injections was -0.2 suggesting that in the population studied there was no relationship between the 2 parameters.
Whilst this analysis suggests that there is no correlation between age and the number of injections, this maybe due to other factors that influence injection numbers such as baseline lesion size and type. Control of such confounding variables may ensure better understanding of the role of the vitreous integrity in the pharmacokinetics of intravitreal therapy.
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