Pachychoroid neovasculopathy with normal subfoveal choroidal thickness

Pachychoriod neovasculopathy and typical neovascular age-related macular degeneration often look similar, but some differences have been described both genotypically and in the level of cytokine profile, which explains the difference in response to antiangiogenic therapy. It is known that pachychoriod diseases are characterized by choroidal subfoveolar thickening. However, there is currently no data on the structural features of the choroid in the presence of pachychoriod neovasculopathy outside the fovea. Purpose. To perform a detailed analysis of choroial structure on OCT scans of patients with neovascular AMD with normal choroidal subfoveolar thickness and to reveal the frequency of pachychoriodal neovasculopathy identification. Material and methods. In retrospective study, the data of 30 treatment-naive patients (30 eyes) aged 71.5±7.6 years with CNV type 1 were analyzed, including 18 women and 12 men, with a subfeolar thickness of the choroidal membrane not exceeding 250 µm. The patients underwent OCT and OCT-angiography using a Spectralis device (Heidelberg Engineering, Germany). In the foveolar zone and under the neovascular complex, if it is located outside the fovea, the structure of the choroid was analyzed: the choroidal thickness, Haller layer and choriocapillaries / layer of Sattler vessels were measured. Results. The average thickness of the choroid in the fovea in all patients was 170.1±40 µm. The thickness of Haller vessels layer was on average 112.3±20 μm, and the layer of choriocapillaries / Sattler vessels was 57.8±12 μm. In 22 eyes, the structure of the choroid and the ratio of all layers were similar in all analyzed OCT scans. However, in 8 eyes, under the CNV located extrafoveally, a thickening of the choroid was revealed up to 210.5±51 µm, the main volume of the choroid was presented by pachyvessels – dilated and enlarged vessels of the Haller layer which thickness was 189.4 ± 48 µm, and thinning of the choriocapillary / Sattler layer to 21.1±16 µm. Conclusion. Among 30 patients with normal subfoveolar thickness of the choroid, the frequency of PNV was 26.6%. Taking into account the literature data on different responses to antiangiogenic therapy in patients with PNV and typical AMD, we can once again emphasize the importance of a detailed assessment of changes in the choroid not only in the foveolar zone, but also specifically in the area of the neovascular complex. Key words: pachychoriod neovasculopathy, choroid, OCT.