Macular vessel density reduction in patients recovered from COVID-19: a longitudinal optical coherence tomography angiography study

The neurovascular retinal involvement in a large population of patients recovered from COVID-19: an OCT and OCT angiography study

BACKGROUND

This study aimed to assess the neuronal and microvascular retinal and choroidal involvement in COVID-19 recovered patients using optical coherence tomography (OCT) and OCT angiography (OCTA).

METHODS

This observational cross-sectional study recruited patients recovered from COVID-19 and a group of healthy controls for comparisons. OCT (peripapillary scan and macular map) and OCTA (macular map) were performed to obtain: the central subfield thickness (CST), the macular volume (MV), the peripapillary retinal nerve fibre layer (pRNFL) thickness, the vessel area density (VAD), vessel length fraction (VLF), vessel diameter index (VDI) and fractal dimension (FD) of the superficial vascular plexus (SVP), intermediate capillary plexus (ICP) and deep capillary plexus (DCP), and the vessel density (VD), stromal density (SD) and vascular/stromal (V/S) ratio of the choriocapillaris (CC) and choroid (Ch). Data regarding disease severity, administered therapy and prior comorbidities were collected.

RESULTS

We recruited 676 eyes from 338 patients and 98 eyes from 49 healthy controls. VAD of all the three retinal plexuses, VLF and VDI of ICP and DCP and VD of CC were significantly reduced in patients versus controls. No differences were found in CST, MV and pRNFL. A multivariate analysis showed that oxygen therapy, previous cardio/cerebrovascular events and hypertension negatively influenced vascular parameters.

CONCLUSION

A microvascular retinal and choriocapillaris damage may be identified secondary to SARS-CoV-2 infection, even after recovery. OCTA may represent a reproducible and non-invasive tool to assess microangiopathy in these patients, with particular regard to those with previous cardio/cerebrovascular events, hypertension and those who received oxygen therapy.

New findings on retinal microvascular changes in patients with primary COVID-19 infection: a longitudinal study

Purpose

To investigate the longitudinal alterations of retinal microvasculature in patients with primary coronavirus disease 2019 (COVID-19) infection.

Methods

A cohort of participants, who had never been infected with COVID-19, was recruited between December 2022 and May 2023 at Peking Union Medical College Hospital in Beijing, China. Participants underwent comprehensive ophthalmologic examinations and fundus imaging, which included color fundus photography, autofluorescence photography, swept-source optical coherence tomography (SS-OCT) and SS-OCT angiography (SS-OCTA). If participants were infected with COVID-19 during the study, follow-ups with consistent imaging modality were conducted within one week and two months after recovery from the infection.

Results

31 patients (61 eyes), with a mean age of 31.0 ± 7.2 years old, were eligible for this study. All participants contracted mild COVID-19 infection within one month of baseline data collection. The average period was 10.9 ± 2.0 days post-infection for the first follow-up and 61.0 ± 3.5 days for the second follow-up. No clinical retinal microvasculopathy features were observed during the follow-ups. However, SS-OCTA analysis showed a significant increase in macular vessel density (MVD) from 60.76 ± 2.88% at baseline to 61.59 ± 3.72%(p=0.015) at the first follow-up, which subsequently returned to the baseline level of 60.23 ± 3.33% (p=0.162) at the two-month follow-up. The foveal avascular zone (FAZ) remained stable during the follow-ups with areas of 0.339 ± 0.097mm2, 0.342 ± 0.093mm2, and 0.344 ± 0.098mm2 at the baseline, first follow-up (p=0.09) and second follow-up (p=0.052), respectively. Central macular thickness, cube volume and ganglion cell-inner plexiform layer showed a transient decrease at the first follow-up(p<0.001, p=0.039, p=0.002, respectively), and increased to baseline level at the two-month follow-up(p=0.401, p=0.368, p=0.438, respectively).

Conclusion

Mild COVID-19 infection may temporarily and reversibly impact retinal microvasculature, characterized by a transient increase in retinal blood flow during the early recovery phase, which returns to the pre-infection level two months post-infection.

Impaired retinal oxygen metabolism and perfusion are accompanied by plasma protein and lipid alterations in recovered COVID-19 patients

The aim of the present study was to investigate retinal microcirculatory and functional metabolic changes in patients after they had recovered from a moderate to severe acute COVID-19 infection. Retinal perfusion was quantified using laser speckle flowgraphy. Oxygen saturation and retinal calibers were assessed with a dynamic vessel analyzer. Arterio-venous ratio (AVR) was calculated based on retinal vessel diameter data. Blood plasma samples underwent mass spectrometry-based multi-omics profiling, including proteomics, metabolomics and eicosadomics. A total of 40 subjects were included in the present study, of which 29 had recovered from moderate to severe COVID-19 within 2 to 23 weeks before inclusion and 11 had never had COVID-19, as confirmed by antibody testing. Perfusion in retinal vessels was significantly lower in patients (60.6 ± 16.0 a.u.) than in control subjects (76.2 ± 12.1 a.u., p = 0.006). Arterio-venous (AV) difference in oxygen saturation and AVR was significantly lower in patients compared to healthy controls (p = 0.021 for AVR and p = 0.023 for AV difference in oxygen saturation). Molecular profiles demonstrated down-regulation of cell adhesion molecules, NOTCH3 and fatty acids, and suggested a bisphasic dysregulation of nitric oxide synthesis after COVID-19 infection. The results of this study imply that retinal perfusion and oxygen metabolism is still significantly altered in patients well beyond the acute phase of COVID-19. This is also reflected in the molecular profiling analysis of blood plasma, indicating a down-regulation of nitric oxide-related endothelial and immunological cell functions.Trial Registration: ClinicalTrials.gov ( https://clinicaltrials.gov ) NCT05650905.

Outer Retinopathies Associated with COVID-19 Infection: Case Reports and Review of Literature

Background

The coronavirus disease (COVID-19) is a highly contagious disease with profound health implications. It can affect any part of the body with variable severity. Various ophthalmic manifestations of coronavirus disease have been documented. Case Presentations. We reported three cases of outer retinopathies associated with COVID-19 infection. All three patients were young females. The first two patients presented within days of COVID-19 infection with complaints of black spots in the eyes. Multimodal retinal imaging showed lesions consistent with acute macular neuroretinopathy. Lesions were bilateral in the first patient and unilateral in the second one. Our third patient presented with blurred vision in one eye, 3 months after a suspected COVID-19 infection. Retinal imaging showed outer retinopathy. Our patients' vision was good and maintained during the follow-up. All three were monitored on observation only, and symptoms and lesions improved with time.

Conclusion

In conclusion, COVID-19-related thromboinflammatory response can result in localized vascular inflammation and hypoperfusion in any of the retinal capillary plexuses or choriocapillaris resulting in ischemia of the corresponding retinal or choroidal layers.

Effects of COVID-19 infection on retinal vascular density and choroidal thickness measured by optical coherence tomography angiography

AIM

The present study evaluates the possible effects of COVID-19 on choroid thickness, the Foveal Avascular Zone (FAZ) and retinal vascular indices in the same individuals who had Optical Coherence Tomography (OCT) and Optical Coherence Tomography Angiography (OCTA) data prior to the COVID-19 pandemic.

METHODS

The OCT and OCTA images of the same individuals with no known ophthalmic pathology who developed a COVID-19 infection were obtained were retrieved retrospectively from the database and compared with the repeated images of OCT and OCTA images 1-2 months after COVID-19 infection.

RESULTS

Eighty eyes of 40 patients (26 female [65%], 14 male [35%]) who had developed a prior Covid-19 infection were included in the study. When comparing the measurements of the same participants before and after Covid-19 infection, no significant difference was detected in the mean average choroidal thicknesses (p=0.998), average superficial (p=0.425) and deep (p=0.333) retinal vascular densities, and superficial (p=0.991) and deep (p=0.075) FAZ measurements.

CONCLUSIONS

No significant effect of COVID-19 on choroid thickness, FAZ or retinal vascular densities was noted in the present study, although there are some studies in literature with equivocal results.

Retinal Microvasculature Image Analysis Using Optical Coherence Tomography Angiography in Patients with Post-COVID-19 Syndrome

Several optical coherence tomography angiography (OCT-A) studies have demonstrated retinal microvascular changes in patients post-SARS-CoV-2 infection, reflecting retinal-systemic microvasculature homology. Post-COVID-19 syndrome (PCS) entails persistent symptoms following SARS-CoV-2 infection. In this study, we investigated the retinal microvasculature in PCS patients using OCT-angiography and analysed the macular retinal nerve fibre layer (RNFL) and ganglion cell layer (GCL) thickness via spectral domain-OCT (SD-OCT). Conducted at the Manchester Royal Eye Hospital, UK, this cross-sectional study compared 40 PCS participants with 40 healthy controls, who underwent ophthalmic assessments, SD-OCT, and OCT-A imaging. OCT-A images from the superficial capillary plexus (SCP) were analysed using an in-house specialised software, OCT-A vascular image analysis (OCTAVIA), measuring the mean large vessel and capillary intensity, vessel density, ischaemia areas, and foveal avascular zone (FAZ) area and circularity. RNFL and GCL thickness was measured using the OCT machine's software. Retinal evaluations occurred at an average of 15.2 ± 6.9 months post SARS-CoV-2 infection in PCS participants. Our findings revealed no significant differences between the PCS and control groups in the OCT-A parameters or RNFL and GCL thicknesses, indicating that no long-term damage ensued in the vascular bed or retinal layers within our cohort, providing a degree of reassurance for PCS patients.

Analysis of Optical Coherence Tomography (OCT) and Optical Coherence Tomography Angiography (OCTA) Parameters in Young Adults after SARS-CoV-2 Infection (COVID-19) Compared with Healthy Young Controls

Purpose: To compare retinal changes in young adults with previous SARS-CoV-2 infection with healthy young controls using optical coherence tomography (OCT) and optical coherence tomography angiography (OCTA). Methods: This prospective single-center study was conducted at the University Hospital of Zurich, Zurich, Switzerland. Participants were imaged from May to November 2021 using the SOLIX device (Visionix International SAS, Pont-de-l’Arche, France). We performed 12 mm × 12 mm, 6.4 mm × 6.4 mm, 6 mm × 6 mm and 3 mm × 3 mm OCT and OCTA scans, as well as fundus photography of each participant’s eyes. Results: In total, 466 participants were imaged. Of these, 233 were healthy controls with negative RT-PCR tests for SARS-CoV-2, 168 were young adults who had a SARS-CoV-2 infection at least 180 days previously, 19 were participants who had a SARS-CoV-2 infection < 180 days previously, and 46 were participants with asymptomatic SARS-CoV-2 infection (i.e., serologically positive but with no symptoms). Compared with healthy controls, statistically significant differences were found for OCTA recordings of the optic disc for the whole image (WI) and WI capillary vessel density, with both being higher in the SARS-CoV-2 group. Conclusion: Statistically significant results were only observed for selected variables, and in parts, only unilaterally, with relatively large p values (p = 0.02–0.03). Thus, we did not interpret these as clinically significant, leading to the conclusion that young and otherwise healthy individuals (mainly men) seem to recover from mild COVID-19 infections with no ophthalmological residues.

The Comparison of Retinal Microvascular Findings in Acute COVID-19 and 1-Year after Hospital Discharge Assessed with Multimodal Imaging-A Prospective Longitudinal Cohort Study

This study aimed to quantify possible long-term impairment of the retinal microcirculation and microvasculature by reassessing a cohort of patients with acute COVID-19 without other known comorbidities one year after their discharge from the hospital. Thirty patients in the acute phase of COVID-19 without known systemic comorbidities were enrolled in this prospective longitudinal cohort study. Fundus photography, SS-OCT, and SS-OCTA using swept-source OCT (SS-OCT, Topcon DRI OCT Triton; Topcon Corp., Tokyo, Japan) were performed in the COVID-19 unit and 1-year after hospital discharge. The cohort's median age was 60 years (range 28-65) and 18 (60%) were male. Mean vein diameter (MVD) significantly decreased over time, from 134.8 μm in the acute phase to 112.4 μm at a 1-year follow-up (p < 0.001). A significantly reduced retinal nerve fiber layer (RNFL) thickness was observed at follow-up in the inferior quadrant of the inner ring (mean diff. 0.80 95% CI 0.01-1.60, p = 0.047) and inferior (mean diff. 1.56 95% CI 0.50-2.61, p < 0.001), nasal (mean diff. 2.21 95% CI 1.16-3.27, p < 0.001), and superior (mean diff. 1.69 95% CI 0.63-2.74, p < 0.001) quadrants of the outer ring. There were no statistically significant differences between the groups regarding vessel density of the superior and deep capillary plexuses. The transient dilatation of the retinal vessels in the acute phase of COVID-19, as well as RNFL thickness changes, could become a biomarker of angiopathy in patients with severe COVID-19.

The impact of acute COVID-19 on the retinal microvasculature assessed with multimodal imaging

PURPOSE

To quantify retinal microvascular findings in the acute phase of COVID-19 using multimodal imaging and compare them with healthy, age-matched controls.

METHODS

Hospitalized patients in the acute phase of COVID-19 without known systemic comorbidities (n = 75) and healthy controls (n = 101) aged 18-65 were enrolled in this prospective cross-sectional study. The retinal microcirculation and microvasculature impairments were assessed using fundus photography, swept-source optical coherence tomography, and swept-source optical coherence tomography angiography in the COVID-19 unit and compared with healthy, age-matched controls.

RESULTS

Retinal findings were predominately observed in patients with severe disease (P = 0.006). Patients with severe disease were shown to have increased both mean vein diameter (Coef. = 19.28, 95% CI: 7.34-31.23, P = 0.002) and mean artery diameter (Coef. = 11.07, 95% CI: 0.84-21.67, P = 0.044). Neither blood vessel diameters were correlated with any confounding variables (age, sex, treatment with oxygen, LDH, or ferritin). Patients with severe COVID-19 were shown to have significantly increased retinal nerve fiber layer thickness in the superior and inferior quadrants both in the inner (S: P = 0.046; I: P = 0.016) and outer (S: P = 0.026; I: P = 0.014) ring and significantly increased GCL thickness in the outer temporal quadrant (P = 0.038). There were no statistically significant differences in vessel density or the foveal avascular zone area between the groups.

CONCLUSION

The severity of COVID-19 was significantly correlated with the presence of retinal microangiopathy, which could become a biomarker of angiopathy in patients with COVID-19.

Evaluation of Retinal Microvascular Impairment after COVID-19 and its Clinical Correlates Using Optical Coherence Tomography Angiography

Objectives

Retinal vascular complications have been described in patients with coronavirus disease 2019 (COVID-19). This study aimed to analyze retinal microvascular changes and their correlations with clinical findings.

Materials and Methods

This case-controlled study was conducted in a university hospital. The right eyes of 52 otherwise healthy patients recovered from COVID-19 and 42 healthy controls were examined with optical coherence tomography angiography. Mann-Whitney U test was used to compare vessel density (VD) and foveal avascular zone (FAZ) parameters. Associations with treatment choices, pneumonia, and laboratory findings were analyzed.

Results

Twenty-nine patients (56%) and 18 healthy controls (43%) were men. Mean age of the COVID-19 group was 39.00±13.04 years. Twenty-two patients had pneumonia, 18 (35%) received hydroxychloroquine (HCQ), 17 (33%) received HCQ plus low-molecular-weight heparin (LMWH), and 10 (19%) received favipiravir. The patient group had lower parafoveal VD in the superficial capillary plexus (SCP) and lower parafoveal VD and perifoveal VD in the deep capillary plexus (DCP) than controls (p=0.003, p=0.004, p=0.001). FAZ area did not differ significantly (p=0.953). Perifoveal VD in the DCP was also significantly lower in the HCQ+LMWH group than the HCQ group (p=0.020) and in the presence of pneumonia (p=0.040). C-reactive protein (CRP) and ferritin levels were negatively correlated with perifoveal VD in the DCP (r=-0.445, p=0.023; r=-0.451, p=0.040). Ferritin was also negatively correlated with parafoveal VD in the SCP (r=-0.532, p=0.013).

Conclusion

Parafoveal and perifoveal VD was found to be lower in the COVID-19 group. Presence of pneumonia, need for LMWH prophylaxis, and levels of CRP and ferritin were found to be negatively associated with retinal VD. Large-scale studies are needed to evaluate the clinical importance.

Optical Coherence Tomography Angiography Analysis of Vessel Density Indices in Early Post-COVID-19 Patients

Purpose

A hypercoagulable state has been reported to cause potential sight-threatening ischemia in patients suffering from Coronavirus disease 2019 (COVID-19). This study aimed to determine whether vessel density (VD), as measured by optical coherence tomography angiography (OCT-A), has insights into retinal and choriocapillaris vascular changes in patients affected by SARS-CoV-2 infection.

Methods

Hundred and fifty two patients positive for SARS-CoV-2 infection were enrolled in this observational, retrospective, controlled study. A control group of 60 healthy subjects was selected for statistical comparisons. Raw OCT and OCT-A data were exported and 3D datasets were analyzed to determine VD.

Results

Hundred and forty eyes (92.1%) were included for final analysis. The VD of the superficial capillary plexus (SCP) did not differ between the two groups. The mean VD of the deep capillary plexus (DCP) and the choriocapillaris (CC) was significantly lower in the foveal sector of the COVID-19 group compared to healthy controls. Within the post-COVID-19 group, the lowest DCP and CC foveal VD values were recorded in patients treated with antiviral therapy; no differences were observed among COVID-19 patients with other comorbidities (hypertension, diabetes, thyroid disease) or taking antiplatelet therapy. DCP and CC foveal VD were significantly lower in patients hospitalized in an intensive care unit (ICU) than asymptomatic patients.

Conclusion

Foveal vessel density at the level of DCP and CC was reduced in post-COVID-19 patients. Further studies evaluating these changes over time will be needed to corroborate the hypothesis of a microvascular retinal impairment in individuals who have recently recovered from SARS-CoV-2 infection.

Spectral-domain optical coherence tomography assessment of retinal and choroidal changes in patients with coronavirus disease 2019: a case-control study

Objectives

This study aimed to evaluate the retinal and choroidal changes in the macular region of patients with Coronavirus Disease 2019 (COVID-19) using structural spectral-domain optical coherence tomography (SD-OCT) analysis.

Methods

This cross-sectional observational case-control study included patients recovered from COVID-19. The COVID-19 in all participants was confirmed using the reverse transcription-polymerase chain reaction (RT-PCR) technique. The participants had mild to moderate degree of disease without a history of hospitalization, steroid usage, or blood saturation below 92%. Macular SD-OCT was performed at least two weeks and up to one month after recovery from systemic COVID-19. Quantitative and qualitative changes detected by macular SD-OCT imaging were evaluated in COVID-19 recovered patients and compared with the results of age-matched normal controls.

Results

Participants in this study included 30 cases (60 eyes) and 60 healthy controls (120 eyes). In total, 17 (28.3%) eyes in patient group showed at least one abnormal finding indicated by macular SD-OCT imaging included hyperreflective lesions in different retinal layers. In addition, dilated choroidal vessels and retinal pigment epitheliopathy were evident in 41 (68.3.6%) and 4 (6.6%) eyes in patient group, respectively, and their OCT findings resembled those with pachychoroid spectrum. No statistically significant differences were observed in retinal layers or retinal volume between the two groups. The mean ± SD subfoveal choroidal thickness (SFCT) was determined at 380.3 ± 12.40 μm, which was significantly thicker than that in control group (310.7 ± 57.5 μm) (P < 0.001).

Conclusion

Regarding retinal thickness, no significant change was observed in different retina layers of patients with COVID-19; however, there were striking qualitative changes, such as hyperreflective lesions in different retinal layers. The evaluation of choroidal structure and thickness demonstrated remarkable abnormal pachyvessels and significant thickening of the SFCT but the clinical significance of these findings is unknown.

Peripapillary Nerve Fiber Layer Thickness and Optic Nerve Head Parameters in Patients Recovered from COVID-19: A Longitudinal Study

Purpose

To quantify the longitudinal changes of the optic nerve head (ONH) parameters and peripapillary retinal nerve fiber layer (pRNFL) thickness in patients recovered from coronavirus disease 2019 (COVID-19) using spectral-domain optical coherence tomography (OCT) analysis.

Materials and Methods

In an observational longitudinal study, in patients recovered from COVID-19, ONH OCT images were recorded at least two weeks after recovery from the systemic disease as the baseline and after one and three-month follow-up. Ganglion cell complex (GCC) analysis, ONH parameters, and pRNFL thickness changes were measured.

Results

A total of 36 eyes from 18 recovered COVID-19 patients including eleven (61.2%) females were studied. The average age was 35.5 ± 7.5 years. The pRNFL thickness in the nasal lower sector significantly decreased from 77 ± 18 μm in the first post-COVID-19 month to 74 ± 10 μm in the third month (P=0.8). The average, superior, and inferior pRNFL thickness remained unchanged. The average cup volume significantly decreased from 0.27 ± 0.15 mm³ at baseline to 0.19 ± 0.15 mm³ in the third post-COVID-19 visit (P=0.028). In terms of ONH morphologies including rim, disc and cup to disc area, and the vertical and horizontal ratio, the changes were not significant over the 3-month study period. Focal loss volume and global loss volume values were not changed significantly.

Conclusion

Localized defect in the nasal lower sector of pRNFL is observed in 3-month post-recovery from COVID-19. Larger studies with longer follow-ups are required to reveal the exact changes in ONH parameters.