State-of-the-art deformable registration algorithms do not perform as well with FA sequences because they are designed to deal with changes of content appearance (e.g., due to different sensors imaging the same organs) but not with content changes, which occur throughout a FA sequence as different portions or the vascular structure are visible (perfused) in different frames. This paper presents a frame-to-frame registration algorithm for ultra-wide-field-of-view (UWFV) fluorescein angiograms (FA) of the retina, based on deformable alignment of the retinal vasculature structure. Comparative experiments on an initial set of UWFV FAs indicate that, thanks to its specialization, our technique outperforms one of the best state-of-the-art methods for multimodal image registration when dealing with the demanding characteristics of the UWFV FA sequences.