The Impact of COVID-19 Infection on Macular Capillary Perfusion

Purpose: To evaluate the impact of a prior non-severe COVID-19 infection on retinal microcirculation with optical coherence tomography angiography (OCTA).Methods:A total of 83 eyes of 43 patients with a history of non-severe COVID-19 infection confirmed with a positive PCR test (Group 1) and 30 age-matched healthy controls (Group 2) underwent detailed eye examination including Spectral-Domain OCT (Topcon-Triton Swept Source) and OCTA (RTVue-XR Avanti) scanning. OCTA images (6x6mm) images were used to assess vessel densities (VD) in superficial capillary plexus (SCP) and deep capillary plexus (DCP) and foveal avascular zone (FAZ). Results:The mean duration between the COVID-19 positive PCR test and ocular examination was 144.6±82.2 days (range: 30-270). VD of SCP and DCP in the foveal and perifoveal regions were significantly lower in Group 1 compared to Group 2 (p<0.05). Conclusion:Non-severe COVID-19 infection may cause a decrease in VD of retinal SCP and DCP.

Improvement of Retinal Microcirculation after Pulmonary Vein Isolation in Patients with Atrial Fibrillation—An Optical Coherence Tomography Angiography Study

Purpose: To evaluate retinal and optic nerve head (ONH) perfusion in patients with atrial fibrillation (AF) before and after catheter ablation of AF with pulmonary vein isolation (PVI). Methods: 34 eyes of 34 patients with AF and 35 eyes of 35 healthy subjects were included in this study. Flow density data were obtained using spectral-domain OCT-A (RTVue XR Avanti with AngioVue, Optovue, Inc, Fremont, California, USA). The data of the superficial and deep vascular layers of the macula and the ONH (radial peripapillary capillary network, RPC) before and after PVI were extracted and analysed. Results: The flow density in the superficial OCT-angiogram (whole en face) and the ONH (RPC) in patients with AF was significantly lower compared to healthy controls (OCT-A superficial: study group: 48.77 (45.19; 52.12)%; control group: 53.01 (50.00; 54.25)%; p < 0.001; ONH: study group: 51.82 (48.41; 54.03)%; control group: 56.00 (54.35; 57.70)%; p < 0.001;). The flow density in the ONH (RPC) improved significantly in the study group following PVI (before: 51.82 (48.41; 54.03)%; after: 52.49 (50.34; 55.62)%; p = 0.007). Conclusions: Patients with AF showed altered ocular perfusion as measured using OCTA when compared with healthy controls. Rhythm control using PVI significantly improved ocular perfusion as measured using OCT-A. Non-contact imaging using OCTA provides novel information about the central global microperfusion of patients with AF.

Spectrally Extended Line Field Optical Coherence Tomography Angiography

The widespread usage of optical coherence tomography angiography (OCTA) is hindered by technical gaps including limited field of view (FOV), lack of quantitative flow information, and suboptimal motion correction. We introduce spectrally extended line field (SELF) OCTA that provides advanced solutions to these challenges. SELF-OCTA breaks the speed limitation and achieves two-fold gain in FOV without sacrificing microvascular details and signal strength through parallel imaging. It also relieves the requirement for shorter exposure time in wide-field applications, so that sufficient sensitivity to slow flow is maintained, particularly in spectral-domain OCT. Towards quantitative angiography, the ‘frequency flow’ mechanism overcomes the speed bottleneck by obviating the requirement for superfluous B-scans. In addition, this mechanism facilitates OCTA-data based motion tracking. Since it can be implemented in existing OCT devices without significant hardware modification or affecting existing functions, SELF-OCTA will make non-invasive, wide-field, quantitative, and low-cost angiographic imaging available to larger patient populations.

Evaluation of Choroidal Thickness Using Optical Coherent Tomography: A Review

The choroid is the main source of blood and nourishment supply to the eye. The dysfunction of the choroid has been implicated in various retinal and choroidal diseases. The identification and in-depth understanding of pachychoroid spectrum disorders are based on the tremendous progress of optical coherence tomography (OCT) technology in recent years, although visibility of choroid is challenging in the era of the time or spectral domain OCT. The recent rapid revolution of OCTs, such as the enhanced depth imaging OCT and the swept-source OCT, has greatly contributed to the significant improvement in the analysis of the morphology and physiology of the choroid precisely, especially to the choroid–scleral boundary and vasculature. The present review highlights the recently available evidence on the measurement methodology and the clinical significance of choroidal thickness in retinal or choroidal disorders.

Symmetry of Peripapillary-Optical Coherence Tomography Angiography Parameters between Dominant and Non-dominant Eyes in Normal Eyes

Purpose: To assess whether optical coherence tomography (OCT) measurements and peripapillary microvascular parameters measured via optical coherence tomography angiography (OCTA) were similar between the dominant and non-dominant eyes of normal subjects.Methods: We retrospectively analyzed spectral domain OCT and OCTA data on healthy Koreans. The “hole-in-the-card” technique was used to determine ocular dominance. The perfusion density (PD) and flux index (FI) of the peripapillary 4.5 × 4.5-mm area were measured via OCTA. Central macular, peripapillary retinal nerve fiber layer, and macular ganglion cell-inner plexiform layer thicknesses were measured with the aid of spectral-domain OCT. The OCT and OCTA data of dominant and non-dominant eyes were compared.Results: A total of 84 eyes of 42 healthy subjects were analyzed. The average age was 27.3 ± 5.63 years. Twenty-eight subjects (66.7%) were right eye-dominant and 14 (33.3%) left eye-dominant. None of the central macular (260.00 ± 14.16 μm, 258.71 ± 15.18 μm, p = 0.183), macular ganglion cell-inner plexiform layer (82.02 ± 5.07 μm, 82.43 ± 5.60 μm, p = 0.460), or peripapillary retinal nerve fiber layer thickness (99.36 ± 9.27 μm, 97.90 ± 9.46 μm, p = 0.091) differed between the eyes; neither did any OCTA-assessed microvascular parameter.Conclusions: No OCT or OCTA parameter differed between dominant and non-dominant eyes. No parameter identified ocular dominance.

Early-stage macular telangiectasia type 2 vascular abnormalities are associated with interdigitation zone disruption

Purpose To investigate the relationship between disruption in different photoreceptor layers and deep capillary plexus (DCP) telangiectasias in eyes with macular telangiectasia type 2 (MacTel). Methods 35 eyes (21 patients) with MacTel imaged with optical coherence tomography angiography (OCTA) were included. Circumscribed areas of DCP telangiectasia were traced from OCTA slabs and the corresponding spectral-domain OCT (SD-OCT) slabs were used to visualize the photoreceptor layer interdigitation zone (IZ) and ellipsoid zone (EZ). IZ attenuation, IZ loss, and EZ loss were graded by reviewing en face SD-OCT slabs for hypo-reflective areas and confirming their status on cross-sectional views. Total area of photoreceptor disruption and overlap with DCP telangiectasia were evaluated with respect to OCT-based MacTel stage. Longitudinal changes were evaluated in a subset of patients with follow-up imaging. Results Overlap of DCP telangiectasia with IZ attenuation significantly decreased with MacTel severity, while overlap with IZ and EZ loss significantly increased. Overlap with IZ loss peaked in moderate MacTel (Stages 3–5). Longitudinal imaging showed that new EZ loss at 6 months was largely predicted by baseline IZ loss. Conclusions Worsening MacTel severity is characterized by greater overlap between DCP telangiectasia and zones of increasing severity of photoreceptor disruption, with EZ loss enlarging over time within areas of preexisting IZ disruption. We suggest that IZ disruption may indicate early photoreceptor dysfunction that eventually progresses to EZ loss, with IZ loss being a more reliable metric than IZ attenuation. Additional studies will be necessary to further explore long-term photoreceptor changes and evaluate their relationship with visual function in MacTel.

Cystoid macular oedema after descemet membrane endothelial keratoplasty

AimsTo determine the incidence and risk factors of cystoid macular oedema (CMO) following descemet membrane endothelial keratoplasty (DMEK) with or without combined cataract surgery (triple-DMEK).MethodsWe reviewed the records of patients who underwent DMEK surgery alone or triple-DMEK performed at the Rothschild Foundation Hospital (Paris, France) between January 2019 and March 2020. Patients with pre-existing CMO observed on the preoperative macular optical coherence tomography (OCT) were excluded. Spectral-domain OCT was performed in patients with postoperative visual impairment. Data regarding comorbidities, intraoperative characteristics and postoperative treatments or complications were collected and analysed. Univariate and multivariate analyses were performed.ResultsTwenty three of 246 eyes (9.36%) developed clinically significant (cs)-CMO after DMEK. Triple-DMEK was not associated with a higher risk to develop CMO (12.2% in DMEK alone and 6.1% in triple-DMEK). Pseudophakic bullous keratopathy (PBK ; 39.1% vs 9%; OR=3.5 (1.0 to 11.8), p=0.045) and epiretinal membrane (ERM; 39.1% vs 7.7%; OR=10.5 (3.4 to 32.3), p<0.001) were more frequently observed in patients who developed CMO. The occurrence of hyphaema during surgery was statistically associated with postoperative CMO (13% vs 1.3%; OR=7.1 (1.0 to 48.8) p=0.045). Peroperative epithelial debridement was statistically associated with postoperative CMO (65.2% vs 33.2%, p=0.005), but only in univariate analysis.ConclusionsWe identified a clinically significant CMO incidence of 9.35% after DMEK. Patients with a history of ERM, PBK and intraoperative hyphaema may be at risk of developing CMO after DMEK surgery and should be monitored.