[Photodynamic therapy follow-up: when to retreat, when to observe, or when to propose an alternative treatment?]

Clinical and angiographic progression after photodynamic therapy (PDT) is usually slow, sometimes fluctuating and therefore difficult to evaluate. After several sessions of PDT, angiographic follow-up remains the basis for therapeutic management involving either a new PDT session or an alternative treatment. It remains difficult, however, to evaluate the activity and progression potential of the remaining neovessels. Imaging (angiography, optical coherence tomography) and functional data both contribute to the therapeutic decision. Certain patients require several sessions for a progressive reduction of the exudation. For others, the persistence of metamorphopsias and accentuation of the scotoma despite the treatment may entail alternative treatment. Thus, a perifoveal photocoagulation can be proposed to limit the extension of the scotoma if after a reasonable number of sessions, central visual acuity is not recovered; direct photocoagulation of a persistent active neovascular contingent, distant from the fixation zone (foveal or exenterated) can be proposed if it remains on the border of a stabilized lesion; the treatment of a feeder vessel can be proposed if it becomes visible and is associated with active neovessels with a persistent central serous detachment of the neuroretina. Lastly, performance status and patient wishes are important elements in the overall therapeutic project, especially if the eye involved is the second eye, in view of quickly initiating low-vision rehabilitation.