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Updated: Jul 17, 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 Guo2
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 Disclosure(S):
Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.
Insights
Fully perfused microaneurysms (MAs) identified with OCT angiography are more likely to be associated with diabetic macular edema (DME). This finding helps understand MA characteristics and their link to DME in diabetic retinopathy.
Area of Science:
- Ophthalmology
- Medical Imaging
- Diabetic Retinopathy Research
Background:
- Microaneurysms (MAs) are key indicators in diabetic retinopathy (DR).
- Their structural characteristics on optical coherence tomography (OCT) and flow on OCT angiography (OCTA) are distinct.
- The quantitative relationship between MAs and macular edema in DR remains underexplored.
Purpose of the Study:
- To quantitatively explore the relationship between microaneurysms and regional macular edema in diabetic retinopathy.
- To classify microaneurysms based on OCT and OCTA findings and assess their association with diabetic macular edema.
Main Methods:
- Retrospective cross-sectional study of 99 participants with diabetic retinopathy.
- Utilized OCT and OCTA for MA identification and classification into fully perfused, partially perfused, and nonperfused types.
- Compared OCT-based MA detection with fundus photography and fluorescein angiography.
Main Results:
- 308 MAs were identified, with 166 fully perfused, 88 partially perfused, and 54 nonperfused.
- Fully perfused MAs showed a higher likelihood of association with local retinal fluid compared to other types.
- OCT/OCTA detected all MAs visible on fundus photography, and some OCT-identified MAs were not visible on fluorescein angiography.
Conclusions:
- Microaneurysms with colocalized flow on OCTA are more strongly associated with diabetic macular edema (DME).
- This classification aids in understanding MA contribution to DME development in DR.
