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Updated: Jul 12, 2025
Evaluation of Capillary and Other Vessel Contribution to Macular Perfusion Density Measured with Optical Coherence Tomography Angiography
Published on: February 18, 2022
Perfused and Nonperfused Microaneurysms Identified and Characterized by Structural and Angiographic OCT
Min Gao1, Tristan T Hormel1, Yukun Guo1,2
1Casey Eye Institute, Oregon Health & Science University, Portland, Oregon.
Purpose:
Microaneurysms (MAs) have distinct, oval-shaped, hyperreflective walls on structural OCT, and inconsistent flow signal in the lumen with OCT angiography (OCTA). Their relationship to regional macular edema in diabetic retinopathy (DR) has not been quantitatively explored.
Design:
Retrospective, cross-sectional study.
Participants:
A total of 99 participants, including 23 with mild, nonproliferative DR (NPDR), 25 with moderate NPDR, 34 with severe NPDR, and 17 with proliferative DR.
Methods:
We obtained 3 × 3-mm scans with a commercial device (Solix, Visionix/Optovue) in 99 patients with DR. Trained graders manually identified MAs and their location relative to the anatomic layers from cross-sectional OCT. Microaneurysms were first classified as perfused if flow signal was present in the OCTA channel. Then, perfused MAs were further classified into fully and partially perfused MAs based on the flow characteristics in en face OCTA. The presence of retinal fluid based on OCT near MAs was compared between perfused and nonperfused types. We also compared OCT-based MA detection to fundus photography (FP)- and fluorescein angiography (FA)-based detection.
Main Outcome Measures:
OCT-identified MAs can be classified according to colocalized OCTA flow signal into fully perfused, partially perfused, and nonperfused types. Fully perfused MAs may be more likely to be associated with diabetic macular edema (DME) than those without flow.
Results:
We identified 308 MAs (166 fully perfused, 88 partially perfused, 54 nonperfused) in 42 eyes using OCT and OCTA. Nearly half of the MAs identified in this study straddle the inner nuclear layer and outer plexiform layer. Compared with partially perfused and nonperfused MAs, fully perfused MAs were more likely to be associated with local retinal fluid. The associated fluid volumes were larger with fully perfused MAs compared with other types. OCT/OCTA detected all MAs found on FP. Although not all MAs seen with FA were identified with OCT, some MAs seen with OCT were not visible with FA or FP.
Conclusions:
OCT-identified MAs with colocalized flow on OCTA are more likely to be associated with DME than those without flow.
Financial Disclosures:
Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article. Ophthalmology Retina 2023;■:1-8 © 2023 by the American Academy of Ophthalmology. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
Insights
Fully perfused microaneurysms (MAs) detected with OCT/OCTA are more likely to correlate with diabetic macular edema (DME). This finding helps understand MA contribution to DME in diabetic retinopathy.
Area of Science:
- Ophthalmology
- Medical Imaging
- Diabetic Retinopathy Research
Background:
- Diabetic retinopathy (DR) is a leading cause of vision loss.
- Microaneurysms (MAs) are early indicators of DR, but their association with macular edema is not fully understood.
- Optical Coherence Tomography Angiography (OCTA) allows for detailed visualization of vascular changes in the retina.
Approach:
- A retrospective cross-sectional study analyzed OCT and OCTA scans from 99 participants with DR.
- Microaneurysms were identified and classified based on the presence and extent of blood flow signal (perfused vs. nonperfused).
- The association between MA perfusion status and the presence of retinal fluid (diabetic macular edema) was quantitatively assessed.
Key Points:
- OCT/OCTA identified 308 MAs, classified as fully perfused, partially perfused, or nonperfused.
- Fully perfused MAs were significantly more likely to be associated with local retinal fluid compared to other types.
- The volume of associated retinal fluid was larger for fully perfused MAs.
- OCT/OCTA demonstrated high sensitivity in detecting MAs compared to fundus photography and fluorescein angiography.
Conclusions:
- OCT-identified microaneurysms with detectable blood flow on OCTA are more strongly associated with diabetic macular edema.
- This classification of MAs based on perfusion status may improve understanding and management of DME in diabetic patients.
- OCTA provides valuable insights into the functional characteristics of MAs in DR.
