Choriocapillaris Flow Impairment in Type 3 Macular Neovascularization

Abstract

Purpose: To quantitatively analyze choriocapillaris alterations using swept-source optical coherence tomography angiography in eyes presenting with Type 3 macular neovascularization (MNV) and to compare these alterations with eyes presenting with intermediate AMD (iAMD). Methods: Macular 3 × 3-mm swept-source optical coherence tomography angiography scans were retrospectively analyzed in eyes with Type 3 MNV and in eyes with iAMD. The choriocapillaris en face slabs were extracted from the swept-source optical coherence tomography angiography device after manual segmentation. En face choriocapillaris flow images were compensated with en face choriocapillaris structure images, followed by the Phansalkar local thresholding method using a window radius of 4 and 8 pixels. The percentage of flow deficits (FD%), the number, size, and total area of FDs were computed for comparison. A secondary analysis was performed in the four corners of the image to include equidistant regions in all eyes. Results: Twenty-six Type 3 MNV eyes of 21 patients and 26 iAMD eyes of 17 patients were included. Compared with iAMD eyes, eyes with Type 3 MNV displayed a higher FD% (41.37% ± 14.74 vs. 19.80% ± 9.63 using radius 4 pixels [P < 0.001]; 45.24% ± 11.9 vs. 26.63% ± 8.96 using radius 8 pixels [P < 0.001]). The average size of FDs was significantly larger in Type 3 MNV eyes compared with iAMD eyes (P < 0.001), whereas the number of FDs was significantly lower in Type 3 MNV compared with iAMD eyes (P < 0.001). Conclusion: Type 3 MNV eyes present with increased choriocapillaris flow impairment compared with iAMD eyes. Reduced choriocapillaris perfusion may contribute to Type 3 MNV development and pathogenesis.

Pushing Retinal Imaging Forward: Innovations and Their Clinical Meaning – The 2022 Ophthalmologica Lecture

“…A subsequent study employing swept-source technology and image compensation with structural information confirmed previous findings of CC hypoperfusion in eyes with type 3 MNV [44]. In this study, 26 type 3 MNV eyes from 21 patients and 26 intermediate AMD eyes from 17 patients were analyzed.…”

Quantitative Analysis of Choriocapillaris Using Swept-Source Optical Coherence Tomography Angiography in Eyes with Angioid Streaks

“…Several authors have hypothesized that a reduced choriocapillaris perfusion and dysfunction of the RPE-Bruch's membrane-choriocapillaris complex can play a role in the development of neovascularization and atrophy, especially in AMD patients. [14][15][16] Angioid streaks, which are visible as grey jagged lines radiating from the optic disc, constitute irregular crack-like dehiscence of the calcified, brittle Bruch's membrane. The Bruch's membrane, which is attached to the RPE, is an elastin-and collagen-rich membrane involved in the transportation of nutrients and metabolites between the RPE and the choriocapillaris [17].…”

“…A swept-source OCTA, compared to a spectral domain OCTA, has the advantage of using a longer wavelength of 1050, allowing a deeper light penetration into the choroid as well as a better determination of macular neovascularization when present. In our study, we used a method of compensation to reduce signal attenuation generated by the RPE-Bruch's membrane complex on the choriocapillaris, as described previously [12,16] Slab selection should also be performed carefully when analyzing the choriocapillaris perfusion. In our study, we used a slab of a thickness of 15 µm, starting 16 µm under the RPE or Bruch's membrane as described by Chu et al [10].…”

Inner and Outer Choroidal Changes in the Fellow Eye of Patients With Unilateral Central Serous Chorioretinopathy

“…15 Both the original and compensated CC OCTA images were binarized with the Phansalkar local thresholding using a window radius of four pixels (26.37 μm) and eight pixels (49.80 μm) as previously described. 16–18…”

“…15 Both the original and compensated CC OCTA images were binarized with the Phansalkar local thresholding using a window radius of four pixels (26.37 mm) and eight pixels (49.80 mm) as previously described. [16][17][18] The final four binarized images (original CC image binarized with a radius of four pixels, original CC image binarized with a radius of eight pixels, compensated CC image binarized with a radius of four pixels, and compensated CC image binarized with a radius of eight pixels) were processed with the "Analyze Particles" command, to count and measure the flow deficits. In details, the following parameters were calculated and included in the analysis: percentage of flow deficits (FD%), number of FD, and average size of FD.…”