OCTA of choroidal microvasculature may facilitate glaucoma diagnoses
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The use of OCT angiography in examining choroidal microvasculature may expedite glaucoma diagnoses in highly myopic eyes, according to findings published in the Journal of Glaucoma.
Hyun-Min Na, MD, and colleagues evaluated the usefulness of OCT angiography (OCTA) imaging of peripapillary choroidal microvasculature in detecting glaucomatous damage in eyes with increased myopia in cases where assessing retinal nerve fiber layer thickness can be unreliable due to OCT segmentation errors.
“Recent studies using OCTA have identified microvasculature dropout [MvD] in the peripapillary choroid of glaucoma patients,” Na, of the department of ophthalmology at Seoul National University College of Medicine at Seoul National University in Korea, and colleagues wrote. “MvD was identified exclusively in primary open-angle glaucoma eyes and its extent was highly consistent with the area of the RNFL defect.”
The researchers examined 45 highly myopic eyes with primary open-angle glaucoma (POAG) and axial lengths greater than 26.5 mm. Fifteen age-matched and 15 axial length-matched control eyes were also included in the study.
Peripapillary choroidal microvasculature was evaluated on en face images obtained using swept-source OCTA, Na and colleagues wrote.
The researchers identified choroidal MvD in 44 of 45 eyes with POAG and high myopia. None of the control eyes showed choroidal MvD.
Choroidal MvD and hemifield visual field defect (0.836; P < .001) have an “excellent topographic relationship,” Ha and colleagues wrote. MvD area (R2 = 0.21619; P = .0006) and circumferential extent (R2 = 0.3088; P = .0002) have a significant association with visual field mean deviation. – by Earl Holland Jr.
Disclosures: The authors report no relevant financial disclosures.
Perspective
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Carolyn E. Majcher, OD, FAAO
OCTA is now widely available, but its novelty leaves doctors struggling to incorporate the technology into everyday clinical practice, especially with regard to glaucoma care. There is rapidly mounting evidence supporting the usefulness of OCTA as an adjunctive tool in glaucoma evaluation particularly in highly myopic eyes, among which OCT nerve fiber layer (NFL) measurements are often plagued by segmentation and decentration errors.
Prior research in such eyes evaluated only the retinal peripapillary vasculature, but recent focus has shifted toward the choroid because both it and the optic nerve head share blood supply from the short posterior ciliary arteries.
This novel OCTA study by Na and colleagues found that nearly all (97.8%) highly myopic eyes with glaucoma and unreliable NFL OCT had peripapillary choroidal vascular dropout compared to none of the highly myopic control eyes without glaucoma. Moreover, the size and extent of dropout was significantly associated with severity of field loss, and its location correlated with the hemifield of vision loss. Although this study utilized swept source OCTA, which is not yet commercially available in the U.S., the implications are exciting and suggest that OCTA may be a valuable tool for detecting and quantifying glaucomatous damage in highly myopic eyes when other objective OCT measures fail.
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