Abstract
Purpose: :
To analyse degree of retinal vascular tortuosity change over time in injected and non-injected eyes of patients receiving Bevacizumab (Avastin®) for the treatment of wet age-related macular degeneration (AMD).
Methods: :
We obtained digital colour images (resolution 2224 x 1888 pixels) from both eyes of 20 patients who had been newly diagnosed with wet AMD in only one eye. These photographs were repeated 11 months later when each eye with wet AMD had been injected 6 times with Bevacizumab and each alternate eye had remained with no wet AMD and no intravitreal injections. Sample size calculations dictated the number of patient’s images that were to be assessed.The VAMPIRE (Vascular Assessment and Measurement Platform for Images of the REtina) software was used to derive a tortuosity index for retinal vessels of each fundal image. VAMPIRE is a semi-automated software application that uses unique published and validated software algorithms to process digital colour fundus photographs and analyse tortuosity of retinal vessels. We compared tortuosity in eyes before treatment with the same eyes after a year of treatment. We also compared tortuosity in eyes after a year of treatment with their fellow eyes that had no intravitreal injections. Differences in tortuosity index between each group of patients were measured with paired student t-tests.
Results: :
There was no significant change in tortuosity of vessels after 11 months of injections with Bevacizumab. We also found no significant difference in tortuosity between injected eyes at month 11 and non-injected eyes at month 11.
Conclusions: :
Using the VAMPIRE tortuosity algorithms, there was no detectable change in tortuosity as a result of repeated injections with Bevacizumab for patients with AMD. This aspect of vascular architecture, in this particular disease seems unaffected by repeated exposure to Bevacizumab, despite obvious effects on neovascularisation.
Keywords: imaging/image analysis: clinical • image processing • age-related macular degeneration