Researchers have shed new light on the link between type 1 choroidal neovascularization (CNV) and the localized progression of atrophy in AMD. The team from the University of Bonn, Germany, analyzed a total of 98 eyes subdivided into three categories: RPE atrophy with treatment-naive quiescent CNV, RPE atrophy with a history of exudative CNV, and RPE atrophy without evidence of coexisting CNV. Atrophy was delineated on the basis of serial fundus-autofluorescence and infrared-reflectance images, with researchers finding markedly reduced RPE atrophy progression in areas co-localizing with quiescent and exudative type 1 CNV.
The takeaway? Type 1 CNV may have a potential protective effect on the RPE. Monika Fleckenstein from the University of Bonn, Germany, and the University of Utah, Salt Lake City, USA, tells us more about the clinical implications of the research.
What were the key results?
Our approach was based on modeling the expected RPE atrophy progression and comparing that with the observed RPE atrophy progression in eyes/regions that co-localized with type 1 CNV. In our study, the odds for future RPE atrophy were reduced by a factor of 0.21 in the presence of treatment-naïve quiescent type 1 CNV. Moreover, the odds for future RPE-atrophy were reduced by the factor of 0.46 in the presence of exudative type 1 CNV.
How do your findings fit within our current understanding of wet and dry AMD?
It is not a new concept that the development of neovascularization may represent a “rescue” mechanism. The development of new vessels may indeed prevent or slow the progression of “dry” AMD – characterized by RPE atrophy – in some patients. However, new vessels may leak (exudate), and the resulting fluid and/or blood accumulates within the retinal tissue/beneath the retina or RPE. This is the “wet” component of the disease that causes severe visual complaints and is usually treated by anti-VEGF. We already know that not all new vessels leak and not all leakage is equally harmful (2). However, we are only just beginning to understand all the underlying mechanisms and their consequences.
What’s next?
We are currently analyzing morphological and systemic factors with a potential impact on new vessel ingrowth in a large patient cohort at the John A. Moran Eye Center at the University of Utah in Salt Lake City, USA. Ultimately, we hope to be able to contribute to a more refined view on neovascularization in AMD and support the development of innovative therapeutic approaches.
- M Pfau et al., “Type 1 choroidal neovascularization is associated with reduced localized progression of atrophy in age-related macular degeneration”, Ophthalmol Retina, 4, 238 (2020). PMID: 31753808.
- T Sato et al., “Tomographic features of branching vascular networks in polypoidal choroidal vasculopathy”, Retina, 27, 589 (2007). PMID: 17558321.
- E Motulsky, PJ Rosenfeld, “Double-layer sign and type 1 CNV”, Retina Specialist (2017). Available at: bit.ly/2LJil2I.
- RH Guymer, The W. Richard Green Lecture presented at the Macula Society Meeting 2019, February 13-16, Bonita Springs, USA.
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