Defining Response to Anti-VEGF Therapies in Neovascular AMD
Defining Response to Anti-VEGF Therapies in Neovascular AMD
The RCOphth guidelines for the management of n-AMD with anti-VEGF therapy recommend the use of both visual function and morphological parameters to guide the diagnosis and management of this disease. Other guidelines or consensus documents have been published by Mitchell et al and Pauliekhoff et al. The change in visual function is assessed by visual acuity (VA) measurement at the baseline and all follow-up visits while the macular morphology is accurately assessed by optical coherence tomography (OCT; spectral domain (SD) or higher specification). OCT is a non-invasive imaging modality of the posterior pole that yields important information on the health of the neurosensory retina, retinal pigment epithelium–Bruch's membrane complex and choroidal vasculature and the modulation of these layers with anti-VEGF therapy. In addition, it aids in the diagnosis and classification of the lesion morphology and activity as depicted by the presence or absence of fluid in the various compartments of the retina–choroidal interface including intraretinal, subretinal and sub-RPE fluid. The tomogram also provides an objective quantification of the amount of fluid.
It is, however, recommended that the clinical diagnosis of n-AMD (CNV) is confirmed by fundus fluorescein angiography (FFA). There are considerable regional variations in the use of indocyanine green angiography (ICGA) as a diagnostic tool for n-AMD. In the United Kingdom, ICGA is not available in all units and is usually reserved for cases presenting with clinical features suspicious of polypoidal choroidopathy (IPCV) or retinal angiomatous proliferation (RAP) or when response to anti-VEGF therapy is suboptimal. On the contrary, ICGA is more important and routinely performed in far eastern countries where IPCV is thought to be more prevalent. Where IPCV is suspected, confirmation with ICGA is required as soon as possible, and ideally within 4 weeks, which could avoid unnecessary dependence on anti-VEGF monotherapy.
Despite the evolution of several regimens for the monitoring of disease activity while on anti-VEGF therapy, the visual outcomes vary significantly from individual to individual, and may be dependent on the lesion type, genetic profile and the starting visual acuity. Similarly, the morphological outcomes may also vary from complete resolution of the lesion to a fibrovascular scar despite presumed adequate monitoring of the disease. Therefore, it is very important to classify the response to therapy in defined categories to better understand the visual potential with a particular treatment option and explore time points when one may decide to switch to another agent.
General Recommendations on Optimal Management of Patients With n-AMD
The RCOphth guidelines for the management of n-AMD with anti-VEGF therapy recommend the use of both visual function and morphological parameters to guide the diagnosis and management of this disease. Other guidelines or consensus documents have been published by Mitchell et al and Pauliekhoff et al. The change in visual function is assessed by visual acuity (VA) measurement at the baseline and all follow-up visits while the macular morphology is accurately assessed by optical coherence tomography (OCT; spectral domain (SD) or higher specification). OCT is a non-invasive imaging modality of the posterior pole that yields important information on the health of the neurosensory retina, retinal pigment epithelium–Bruch's membrane complex and choroidal vasculature and the modulation of these layers with anti-VEGF therapy. In addition, it aids in the diagnosis and classification of the lesion morphology and activity as depicted by the presence or absence of fluid in the various compartments of the retina–choroidal interface including intraretinal, subretinal and sub-RPE fluid. The tomogram also provides an objective quantification of the amount of fluid.
It is, however, recommended that the clinical diagnosis of n-AMD (CNV) is confirmed by fundus fluorescein angiography (FFA). There are considerable regional variations in the use of indocyanine green angiography (ICGA) as a diagnostic tool for n-AMD. In the United Kingdom, ICGA is not available in all units and is usually reserved for cases presenting with clinical features suspicious of polypoidal choroidopathy (IPCV) or retinal angiomatous proliferation (RAP) or when response to anti-VEGF therapy is suboptimal. On the contrary, ICGA is more important and routinely performed in far eastern countries where IPCV is thought to be more prevalent. Where IPCV is suspected, confirmation with ICGA is required as soon as possible, and ideally within 4 weeks, which could avoid unnecessary dependence on anti-VEGF monotherapy.
Despite the evolution of several regimens for the monitoring of disease activity while on anti-VEGF therapy, the visual outcomes vary significantly from individual to individual, and may be dependent on the lesion type, genetic profile and the starting visual acuity. Similarly, the morphological outcomes may also vary from complete resolution of the lesion to a fibrovascular scar despite presumed adequate monitoring of the disease. Therefore, it is very important to classify the response to therapy in defined categories to better understand the visual potential with a particular treatment option and explore time points when one may decide to switch to another agent.
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