Analysis of Blood Flow in the Macula and Optic Nerve Head in Healthy Young Volunteers Using Laser Speckle Flowgraphy.

PURPOSE: To assess optic nerve head (ONH) and macular blood flow in young healthy volunteers using laser speckle flowgraphy (LSFG). METHODS: This is a prospective single-center study conducted at the Department of Ophthalmology, University Hospital Zurich from May to November 2021. Young, healthy men aged ≥ 18 years without ocular or systemic diseases were included. A corrected visual acuity (VA) of 0.0 logMAR or better in both eyes and an intraocular pressure (IOP) of 21 mmHg or lower were required for inclusion. Subjects exceeding a spherical equivalent (SE) of ± 6 diopters (dpt) were excluded. Blood flow in the macula and the ONH was recorded using the Nidek LSFG RetFlow device (Nidek Company, Ltd., Hirioshi-cho, Japan). Laser power was set to 0.5 Millivolts (mV). Mean blur rate (MBR) was recorded as a parameter for blood flow. MBR is a calculated parameter that represents relative blood flow velocity correlated with the real anatomical blood flow rate. Colored heat maps of the recorded retinal area were generated automatically by the RetFlow device. RESULTS: Final analyses included 83 eyes of 43 male volunteers. Mean age was 21.9 years (SD ± 1.5, range: 20 to 29). Mean corrected VA was - 0.1 logMAR (SD ± 0.05, range: - 0.2 to 0.0), mean IOP was 15.4 mmHg (SD ± 2.5, range: 8.5 to 18.5), and mean SE was - 0.3 dpt (SD ± 1.2, range: - 5.0 to 1.2). Mean ONH MBR was 37.44 (SD ± 7.9, range: 22.5 to 53.5) and mean macular MBR was 27.8 (SD ± 9.7, range: 6.4 to 57.7). Pearson's Test showed a strong correlation between macular and papillary blood flow (p < 0.05, coefficient: 0.647). CONCLUSION: This study provides both ONH and macular blood flow data in a healthy young male population, showing a strong correlation between ONH and macular blood flow in the examined eyes. Further investigations are required to assess the validity of MBR as a parameter for the combined evaluation of retinal blood flow at the macula and ONH in healthy volunteers and patients with various diseases.

Differences in Mean Values and Variance in Quantitative Analyses of Foveal OCTA Imaging.

PURPOSE: Multiple approaches for quantifying parameters such as vessel density (VD) and vessel length density (VLD) in optical coherence tomography angiography (OCTA) en-face segmentations are currently available. While it is common knowledge that data gathered from different methods should not be directly compared to each other, a comparison of the different methods can help to further the understanding of differences between different methods of measurement. Here we compare a common method of semiautomatically quantifying VD and VLD with an automated method supplied by the manufacturer of an OCTA device and report on differences in performance in order to probe for and highlight differences in values gathered by both methods. METHODS: OCTA was performed using the swept source PLEX Elite 9000 device, software version 2.0.1.47652 (Carl Zeiss Meditec Inc., Dublin, CA, USA). Scans of 3 mm × 3 mm from healthy volunteers centred on the fovea were acquired by a well-trained certified ophthalmologist. Scans with a signal strength of 8 out of 10 or higher were included. Quantitative parameters of the 3 mm × 3 mm cube scans were automatically generated and segmented into superficial capillary plexus (SCP) and deep capillary plexus (DCP) layers using layer segmentation produced by the instrument software and prototype analysis VD quantification software (Macular Density v.0.7.1, ARI Network Hub, Carl Zeiss Meditec Inc., Dublin, CA, USA) supplied by the manufacturer. An alternative approach of quantitative analysis of VD and VLD was performed manually with ImageJ (National Institutes of Health, Bethesda, Maryland, USA), as previously reported. VD was assessed as the ratio of the retinal area occupied by vessels. VDL was measured as the total length of the skeletonised vessels using 1-pixel centre line extraction of the blood vessels. RESULTS: We report differences in standard deviation (SD) in OCTA parameters obtained using different methods. The standard deviation of VD and VLD measurements was statistically significantly different in VD of 3 mm × 3 mm DCP (p = 0.009), VLD of 3 mm × 3 mm SCP (p = 0.000), and VLD of 3 mm × 3 mm DCP (p = 0.021). No statistically significant differences were found in VD of 3 mm × 3 mm SCP (p = 0.128) or VLD of 3 mm × 3 mm SCP (p = 0.107). CONCLUSIONS: As expected, we were able to demonstrate significant differences in quantitative OCTA parameters gathered from the same images using different methods of quantification. Values gathered using different methods are not interchangeable. In scientific studies and in situations where long-term follow-up is necessary, the same device and the same method of quantification should be used to maintain retrospective comparability of measurements.

Smartphone Slit Lamp Imaging-Usability and Quality Assessment.

PURPOSE: To assess the usability and image quality of a smartphone adapter for direct slit lamp imaging. METHODS: A single-center, prospective, clinical study conducted in the Department of Ophthalmology at the University Hospital Zurich, Switzerland. The smartphone group consisted of 26 medical staff (consultants, residents, and students). The control group consisted of one ophthalmic photographer. Both groups took images of the anterior and the posterior eye segment of the same proband. The control group used professional photography equipment. The participant group used an Apple iPhone 11 mounted on a slit lamp via a removable SlitREC smartphone adapter (Custom Surgical GmbH, Munich, Germany). The image quality was graded independently by two blinded ophthalmologists on a scale from 0 (low) to 10 (high quality). Images with a score ≥ 7.0/10 were considered as good as the reference images. The acquisition time was measured. A questionnaire on usability and experience in smartphone and slit lamp use was taken by all of the participants. RESULTS: Each participant had three attempts at the same task. The overall smartphone quality was 7.2/10 for the anterior and 6.4/10 for the posterior segment. The subjectively perceived difficulty decreased significantly over the course of three attempts (Kendall's W). Image quality increased as well but did not improve significantly from take 1 to take 3. However, the image quality of the posterior segment was significantly, positively correlated (Spearman's Rho) with work experience. The mean acquisition time for anterior segment imaging was faster in the smartphone group compared to the control group (156 vs. 206 s). It was vice versa for the posterior segment (180 vs. 151 s). CONCLUSION: Slit lamp imaging with the presented smartphone adapter provides high-quality imaging of the anterior segment. Posterior segment imaging remains challenging in terms of image quality. The adapter constitutes a cost-effective, portable, easy-to-use solution for recording ophthalmic photos and videos. It can facilitate clinical documentation and communication among colleagues and with the patient especially outside normal consultation hours. Direct slit lamp imaging allows for time to be saved and increases the independence of ophthalmologists in terms of patient mobility and the availability of photographic staff.

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.

Incidence and Risk Factors of Visual Impairment in Patients with Angioid Streaks and Macular Neovascularization.

OBJECTIVE: To estimate the incidence and risk factors of visual impairment and complications in eyes with macular neovascularization (MNV) because of angioid streaks (ASs). DESIGN: Longitudinal multicenter retrospective cohort study. SUBJECTS: Patients with AS-associated MNV treated with anti-VEGF agents and a follow-up of > 3 months. METHODS: Clinical and MNV characteristics were collected at baseline. Visual acuity (VA) values and the presence of atrophy or fibrosis were collected at each visit. MAIN OUTCOME MEASURES: Rate of VA change over time and associated factors; the incidence rate of moderate-to-severe visual impairment (MSVI) and blindness and hazard ratio (HR) of candidate risk factors for MSVI; the incidence rate of fibrosis and macular atrophy. RESULTS: Overall, 84 eyes of 66 patients (39 men, 58%) with a mean (standard deviation) age of 55.7 (13.8) years were followed for a mean (standard deviation) of 67.7 (48.5) months. The median number of anti-VEGF doses per eye was 13. The average rate (95% confidence interval [CI]) of visual loss was +0.04 (0.02-0.06) logarithm of the minimum angle of resolution/year (P < 0.001); the visual loss was faster in nonnaive eyes (P = 0.007) and those with better baseline VA (P < 0.001); it was slower in eyes with pattern dystrophy-like features (P = 0.04). The incidence rates (95% CI) of MSVI and blindness were 10.4 (6.88-15)/100-eye-years and 2.33 (1.12-4.29)/100-eye-years. A higher number of injections (HR [95% CI] = 0.45 [0.19-0.94] for receiving ≥ 13 injections vs. < 13; P = 0.03) was protective against MSVI. The incidence rates (95% CI) of fibrosis and macular atrophy were 24.1 (17.5-32.3)/100-eye-years and 14.3 (10.1-19.6)/100-eye-years. CONCLUSIONS: Eyes with MNV-related AS had a high rate of visual impairment and propensity to macular fibrosis and atrophy. A higher number of injections yielded better chances of maintaining good VA, suggesting the need for intensive treatment. FINANCIAL DISCLOSURE(S): Proprietary or commercial disclosure may be found after the references.

Differences between Mycobacterium chimaera and tuberculosis Using Ocular Multimodal Imaging: A Systematic Review.

Due to their non-specific diagnostic patterns of ocular infection, differential diagnosis between Mycobacterium (M.) chimaera and tuberculosis can be challenging. In both disorders, ocular manifestation can be the first sign of a systemic infection, and a delayed diagnosis might reduce the response to treatment leading to negative outcomes. Thus, it becomes imperative to distinguish chorioretinal lesions associated with M. chimaera, from lesions due to M. tuberculosis and other infectious disorders. To date, multimodal non-invasive imaging modalities that include ultra-wide field fundus photography, fluorescein and indocyanine green angiography, optical coherence tomography and optical coherence tomography angiography, facilitate in vivo examination of retinal and choroidal tissues, enabling early diagnosis, monitoring treatment response, and relapse detection. This approach is crucial to differentiate between active and inactive ocular disease, and guides clinicians in their decisional-tree during the patients' follow-up. In this review, we summarized and compared the available literature on multimodal imaging data of M. chimaera infection and tuberculosis, emphasizing similarities and differences in imaging patterns between these two entities and highlighting the relevance of multimodal imaging in the management of the infections.