Effect of manual OCTA segmentation correction to improve image quality and visibility of choroidal neovascularization in AMD.

In this retrospective case series on neovascular age-related macular degeneration (nAMD), we aimed to improve Choroidal Neovascularization (CNV) visualization in Optical Coherence Tomography Angiography (OCTA) scans by addressing segmentation errors. Out of 198 eyes, 73 OCTA scans required manual segmentation correction. We compared uncorrected scans to those with minimal (2 corrections), moderate (10 corrections), and detailed (50 corrections) efforts targeting falsely segmented Bruch's Membrane (BM). Results showed that 55% of corrected OCTAs exhibited improved quality after manual correction. Notably, minimal correction (2 scans) already led to significant improvements, with additional corrections (10 or 50) not further enhancing expert grading. Reduced background noise and improved CNV identification were observed, with the most substantial improvement after two corrections compared to baseline uncorrected images. In conclusion, our approach of correcting segmentation errors effectively enhances image quality in OCTA scans of nAMD. This study demonstrates the efficacy of the method, with 55% of resegmented OCTA images exhibiting enhanced quality, leading to a notable increase in the proportion of high-quality images from 63 to 83%.

ARTIFICIAL INTELLIGENCE FOR OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY-BASED DISEASE ACTIVITY PREDICTION IN AGE-RELATED MACULAR DEGENERATION.

PURPOSE: The authors hypothesize that optical coherence tomography angiography (OCTA)-visualized vascular morphology may be a predictor of choroidal neovascularization status in age-related macular degeneration (AMD). The authors thus evaluated the use of artificial intelligence (AI) to predict different stages of AMD disease based on OCTA en face 2D projections scans. METHODS: Retrospective cross-sectional study based on collected 2D OCTA data from 310 high-resolution scans. Based on OCT B-scan fluid and clinical status, OCTA was classified as normal, dry AMD, wet AMD active, and wet AMD in remission with no signs of activity. Two human experts graded the same test set, and a consensus grading between two experts was used for the prediction of four categories. RESULTS: The AI can achieve 80.36% accuracy on a four-category grading task with 2D OCTA projections. The sensitivity of prediction by AI was 0.7857 (active), 0.7142 (remission), 0.9286 (dry AMD), and 0.9286 (normal) and the specificity was 0.9524, 0.9524, 0.9286, and 0.9524, respectively. The sensitivity of prediction by human experts was 0.4286 active choroidal neovascularization, 0.2143 remission, 0.8571 dry AMD, and 0.8571 normal with specificity of 0.7619, 0.9286, 0.7857, and 0.9762, respectively. The overall AI classification prediction was significantly better than the human (odds ratio = 1.95, P = 0.0021). CONCLUSION: These data show that choroidal neovascularization morphology can be used to predict disease activity by AI; longitudinal studies are needed to better understand the evolution of choroidal neovascularization and features that predict reactivation. Future studies will be able to evaluate the additional predicative value of OCTA on top of other imaging characteristics (i.e., fluid location on OCT B scans) to help predict response to treatment.

Ultra-wide field and new wide field composite retinal image registration with AI-enabled pipeline and 3D distortion correction algorithm.

PURPOSE: This study aimed to compare a new Artificial Intelligence (AI) method to conventional mathematical warping in accurately overlaying peripheral retinal vessels from two different imaging devices: confocal scanning laser ophthalmoscope (cSLO) wide-field images and SLO ultra-wide field images. METHODS: Images were captured using the Heidelberg Spectralis 55-degree field-of-view and Optos ultra-wide field. The conventional mathematical warping was performed using Random Sample Consensus-Sample and Consensus sets (RANSAC-SC). This was compared to an AI alignment algorithm based on a one-way forward registration procedure consisting of full Convolutional Neural Networks (CNNs) with Outlier Rejection (OR CNN), as well as an iterative 3D camera pose optimization process (OR CNN + Distortion Correction [DC]). Images were provided in a checkerboard pattern, and peripheral vessels were graded in four quadrants based on alignment to the adjacent box. RESULTS: A total of 660 boxes were analysed from 55 eyes. Dice scores were compared between the three methods (RANSAC-SC/OR CNN/OR CNN + DC): 0.3341/0.4665/4784 for fold 1-2 and 0.3315/0.4494/4596 for fold 2-1 in composite images. The images composed using the OR CNN + DC have a median rating of 4 (out of 5) versus 2 using RANSAC-SC. The odds of getting a higher grading level are 4.8 times higher using our OR CNN + DC than RANSAC-SC (p < 0.0001). CONCLUSION: Peripheral retinal vessel alignment performed better using our AI algorithm than RANSAC-SC. This may help improve co-localizing retinal anatomy and pathology with our algorithm.

Efficacy and accuracy of artificial intelligence to overlay multimodal images from different optical instruments in patients with retinitis pigmentosa.

BACKGROUND: Retinitis pigmentosa (RP) represents a group of progressive, genetically heterogenous blinding diseases. Recently, relationships between measures of retinal function and structure are needed to help identify outcome measures or biomarkers for clinical trials. The ability to align retinal multimodal images, taken on different platforms, will allow better understanding of this relationship. We investigate the efficacy of artificial intelligence (AI) in overlaying different multimodal retinal images in RP patients. METHODS: We overlayed infrared images from microperimetry on near-infra-red images from scanning laser ophthalmoscope and spectral domain optical coherence tomography in RP patients using manual alignment and AI. The AI adopted a two-step framework and was trained on a separate dataset. Manual alignment was performed using in-house software that allowed labelling of six key points located at vessel bifurcations. Manual overlay was considered successful if the distance between same key points on the overlayed images was ≤1/2°. RESULTS: Fifty-seven eyes of 32 patients were included in the analysis. AI was significantly more accurate and successful in aligning images compared to manual alignment as confirmed by linear mixed-effects modelling (p < 0.001). A receiver operating characteristic analysis, used to compute the area under the curve of the AI (0.991) and manual (0.835) Dice coefficients in relation to their respective 'truth' values, found AI significantly more accurate in the overlay (p < 0.001). CONCLUSION: AI was significantly more accurate than manual alignment in overlaying multimodal retinal imaging in RP patients and showed the potential to use AI algorithms for future multimodal clinical and research applications.

Retinal tissue and microvasculature loss in COVID-19 infection.

This cross-sectional study aimed to investigate the hypothesis that permanent capillary damage may underlie the long-term COVID-19 sequela by quantifying the retinal vessel integrity. Participants were divided into three subgroups; Normal controls who had not been affected by COVID-19, mild COVID-19 cases who received out-patient care, and severe COVID-19 cases requiring intensive care unit (ICU) admission and respiratory support. Patients with systemic conditions that may affect the retinal vasculature before the diagnosis of COVID-19 infection were excluded. Participants underwent comprehensive ophthalmologic examination and retinal imaging obtained from Spectral-Domain Optical Coherence Tomography (SD-OCT), and vessel density using OCT Angiography. Sixty-one eyes from 31 individuals were studied. Retinal volume was significantly decreased in the outer 3 mm of the macula in the severe COVID-19 group (p = 0.02). Total retinal vessel density was significantly lower in the severe COVID-19 group compared to the normal and mild COVID-19 groups (p = 0.004 and 0.0057, respectively). The intermediate and deep capillary plexuses in the severe COVID-19 group were significantly lower compared to other groups (p < 0.05). Retinal tissue and microvascular loss may be a biomarker of COVID-19 severity. Further monitoring of the retina in COVID-19-recovered patients may help further understand the COVID-19 sequela.

Effect of a Dexamethasone Implant on Rheological Blood Parameters in Patients Treated for Retinal Vein Thrombosis.

Purpose: To assess the effect of the prolonged-release dexamethasone implant (Ozurdex) in patients with retinal venous thrombosis on blood rheological parameters and evaluate the impact on morphological and functional parameters. Methods: Prospective cross-sectional study involved 35 subjects treated with central retinal vein and vein branch occlusion with intravitreal dexamethasone implant and 35 healthy subjects in control group. Hematocrit, blood and plasma viscosity, erythrocyte aggregation amplitude (EAA), index (EAI), aggregation half-life time (EAT1/2), and erythrocyte deformability (ED) were evaluated. The best-corrected visual acuity (BCVA), central retinal thickness (CRT) and visual field (VF) were examined. All the parameters were examined at the baseline, 7 and 30 days after the treatment. The results were analyzed with correlation and regression and compared to the baseline values. Results: In the studied group, three hemorheological parameters improved as early as on the 7th day after the drug administration, and this improvement remained at a similar level on the 30th day. The EAA increased by 21.26% on day 7 and by 19.78% on day 30, the EAI decreased by 10.55% on day 7 and by 9.14% on day 30 and the EAT1/2 time increased by 38.50% on day 7 and by 31.02% on day 30. On day 7, the BCVA was improved by 1 row, CRT was reduced by 170.77 µm (24.49%), and the VF was improved by 9.8 dB (49.92%) compared to baseline parameters. On day 30, the BCVA was improved by three rows, CRT reduced by 244.68 µm (35.09%), and VF improved by 12.09 dB (61.59%). Conclusion: The intravitreal dexamethasone implant used in treating macular oedema in patients with RVO has a statistically significant effect on some rheological parameters of blood, reduction of CRT and clinical improvement in BCVA and VF.

Effective treatment of retinal neovascular leakage with fusogenic porous silicon nanoparticles delivering VEGF-siRNA.

Aim: To evaluate an intravitreally injected nanoparticle platform designed to deliver VEGF-A siRNA to inhibit retinal neovascular leakage as a new treatment for proliferative diabetic retinopathy and diabetic macular edema. Materials & methods: Fusogenic lipid-coated porous silicon nanoparticles loaded with VEGF-A siRNA, and pendant neovascular integrin-homing iRGD, were evaluated for efficacy by intravitreal injection in a rabbit model of retinal neovascularization. Results: For 12 weeks post-treatment, a reduction in vascular leakage was observed for treated diseased eyes versus control eyes (p = 0.0137), with a corresponding reduction in vitreous VEGF-A. Conclusion: Fusogenic lipid-coated porous silicon nanoparticles siRNA delivery provides persistent knockdown of VEGF-A and reduced leakage in a rabbit model of retinal neovascularization as a potential new intraocular therapeutic.

Two Year Study of Aflibercept and Ranibizumab Intravitreal Therapy in Patients with Wet AMD.

Background and objectives: The aim of this study was to evaluate the therapeutic results in patients with exudative AMD treated with ranibizumab and aflibercept intravitreal injections over a two-year observation period. Materials and methods: A retrospective observational study was conducted in a clinical hospital on a group of patients who randomly qualified for treatment with Aflibercept (group A) and Ranibizumab (group B) as part of the Polish National Health Fund Medical Program for exudative AMD. Group A consisted of 90 patients, and group B contained 54 patients. The choice of drug in a patient depended solely on the availability of the medication at the time. Before each injection, best corrected visual acuity (BCVA) on the ETDRS scale and central retinal thickness (CRT) were assessed using optical coherence tomography (OCT). Patients from both groups were treated in the first year of treatment with a rigid scheme of 3 doses of 2.0 mg Aflibercept (group A) and 0.5 mg Ranibizumab (group B) at monthly intervals, followed by 4 doses at bimonthly intervals. In the second year, a "pro re nata" scheme was applied. The aim was to evaluate changes in BCVA and CRT after three injections, after 7 injections (about 12 months), and after the second year of therapy (24 months) with reference to the baseline and to compare the effectiveness of the medications. The influences of the following factors were studied: age, gender, initial BCVA, and initial CRT, as well as the number of injections received. Results: No significant statistical differences were found between patients receiving Aflibercept and Ranibizumab therapy in terms of achieving improved visual acuity and reducing retinal thickness after two years of therapy. Conclusions: Both aflibercept and ranibizumab were found to be effective for treating exudative AMD.

Optical coherence tomography angiography features in patients with idiopathic full-thickness macular hole, before and after surgical treatment.

PURPOSE: To present optical coherence tomography (OCT) angiography features in patients with idiopathic full-thickness macular hole before and after vitrectomy. STUDY DESIGN: Prospective case series study. MATERIALS AND METHODS: Patients presenting with an idiopathic full-thickness macular hole (IMH) who underwent posterior vitrectomy with internal limiting membrane peeling and gas tamponade were included in the study. En face OCT and OCT angiography (OCTA) was performed pre- and postoperatively using 3×3 mm scans (Optovue, XR Avanti). Foveal avascular zone (FAZ) area, macular hole size (MHS), central retinal thickness (CRT), macular parafoveal choriocapillary flow area (MCFA), and fovea vessel density (FVDS) were measured and assessed using OCTA. Best-corrected visual acuity (BCVA) was examined before and 3 months after surgery. RESULTS: Twenty-eight eyes of 28 patients were included in the study. The mean age of patient group was 68.28 years. The hole was closed in all eyes after the initial surgery. OCTA showed enlargement of FAZ and increased CRT in foveal area. Mean preoperative FAZ area was 0.39±0.07 mm2. En face images of the middle retina showed a range of preoperative cystic patterns surrounding the hole. BCVA was improved from 0.1±0.11 preoperatively to 0.42±0.17 postoperatively. Mean FAZ area was reduced to 0.24±0.07 mm2 postoperatively with resolution of macular hole and adjacent cystic areas. Mean CRT was reduced from 396±62.6 µm pre-operatively to 272±30.7 µm postoperatively. After vitrectomy, the parafoveal choriocapillary flow area and FVDS of IMH eyes increased compared with the preoperative measurements. CONCLUSION: Quantitative evaluation of vascular and morphological changes following IMH surgery using OCTA shows the potential for recovery due to vascular and neuronal plasticity. OCTA showing vascular changes and their quantitative characteristics might be a useful tool for the assessment of macular holes before and after surgical treatment.