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    Retinal Abnormalities and COVID

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    Retinal microvascular abnormalities and impaired blood flow ap­pear to be emerging as signature ocular manifestations of COVID-19 infections, researchers have found.1,2 The abnor­malities, which have been observed even in otherwise healthy eyes, support the hypothesis of widespread microvas­cular damage that could be clinically silent in those who have had COVID.2

    After COVID

    AFTER COVID. Retinal abnormalities, as seen on color fundus and red-free images, included (top) retinal microhemorrhages and (bottom) peripapillary cotton-wool spots (green arrows).

    Study in Singapore. In Singapore, a prospective study of 108 COVID-positive subjects found that 1 in 9 had retinal microvascular signs.1 The abnormal findings included eight eyes (3.7%) with microhemorrhages, six (2.8%) with retinal vascular tortuosity, and two (0.93%) with cotton-wool spots. OCT scans revealed 11 eyes (5.1%) with hyper-reflective plaques in the ganglion cell-inner plexiform layer—and two of those eyes also had retinal signs visible on color fundus photographs.

    Underlying cardiovascular impact? “These signs were observed even in asymptomatic patients with normal vital signs and no past history of cardiovascular disease. These retinal micro­vascular signs could represent under­lying cardiovascular and thrombotic alterations associated with COVID-19 infection,” said Chee Wai Wong, MBBS, MMed(Ophth), at the Singapore Na­tional Eye Centre and the Duke-NUS Medical School.

    Moreover, the scientists found that COVID patients with retinal signs were signifi­cantly more likely to have elevated blood pressure than were those without such signs (p = .03), Dr. Wong said. “Serial mon­itoring of these patients showed normalization of blood pressure as they re­covered from COVID-19. Hence, there may be a role in triaging patients for eye screening based on serial monitoring of blood pressure,” he said.

    Study in Italy. Italian researchers performed OCT and OCT angiography (OCTA) on the retinas of 40 patients who had recovered from SARS-CoV-2 pneumonia and compared them to 40 healthy control subjects.2

    All of the post-COVID patients had normal ocular and fundus exam­inations, and none reported eye symp­toms. Nonetheless, the OCTA images showed significant, diffuse perfusion loss in several areas of the post-COVID patients’ retinas, compared to controls, the researchers reported.

    Alterations in retinal blood flow. The density of deep capillary vessels was reduced in all macular regions, as was vessel density in the superficial capillary plexus (p = .038) and the radi­al peripapillary capillaries (p < .001). Structural OCT showed lower average thickness of the retinal nerve fiber layer (p = .012), and this correlated signifi­cantly with the angiographic data.

    Alterations in retinal blood flow could reflect a variety of pathogenic mechanisms that have been linked to SARS-CoV-2 infection, including thromboinflammatory microangiopa­thy and angiotensin-converting enzyme 2 disruption, the authors said.

    If the group’s findings are confirmed by larger studies, OCTA images might help physicians to better anticipate or prevent systemic deterioration in their COVID patients, the researchers wrote. “OCTA allows [physicians] to detect the signs of retinal thrombotic micro­angiopathy that could reflect the sys­temic vascular impairment occurring in multiorgan dysfunction. OCTA could represent a valid biomarker of systemic vascular dysfunction after SARS-CoV-2 infection.”

    —Linda Roach


    1 Sim R et al. Br J Ophthalmol. 2021;227:182-190.

    2 Cennamo G et al. Am J Ophthalmol. Published online March 26, 2021.


    Relevant financial disclosures—Dr. Wong: None.

    For full disclosures and the disclosure key, see below.

    Full Financial Disclosures

    Dr. Crama None.

    Dr. Gillmann None.

    Dr. Mansouri Allergan: S; ImplanData: C; Santen: C; Sensimed: C.

    Dr. Ramanathan None.

    Dr. Wong None.

    Disclosure Category



    Consultant/Advisor C Consultant fee, paid advisory boards, or fees for attending a meeting.
    Employee E Employed by a commercial company.
    Speakers bureau L Lecture fees or honoraria, travel fees or reimbursements when speaking at the invitation of a commercial company.
    Equity owner O Equity ownership/stock options in publicly or privately traded firms, excluding mutual funds.
    Patents/Royalty P Patents and/or royalties for intellectual property.
    Grant support S Grant support or other financial support to the investigator from all sources, including research support from government agencies (e.g., NIH), foundations, device manufacturers, and/or pharmaceutical companies.


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