Swept-source Optical Coherence Tomography Images Research Articles

Analysis of Choriocapillaris Reperfusion Topography Following Faricimab Treatment for Neovascular Age-Related Macular Degeneration in Therapy-Naïve Patients.

To assess changes in choriocapillaris (CC) vascular density surrounding macular neovascularization (MNV) in treatment-naïve age-related macular degeneration (AMD) after faricimab application using optical coherence tomography angiography (OCTA). Twenty-five eyes of 25 treatment-naïve individuals who underwent intravitreal faricimab injections for neovascular AMD (nAMD) with type 1 MNV were included. Spectral-domain optical coherence tomography (SD-OCT) images and en-face swept-source OCTA images were analyzed, and the percentage of CC flow deficit (FD%), FD average area (FDa) and FD number (FDn) in five progressive 20.0-μm-wide concentric rings (R1, R2, R3, R4 and R5) surrounding the dark halo around the MNV were calculated. Image acquisition was carried out prior to the first faricimab injection (T0) and 1 month after the injection (T1). The topographical sub-analysis revealed noteworthy changes in all rings at T1 compared to T0. There was a notable progressive reduction in FD% at T1 compared to T0 values across all rings, indicating a gradual CC reperfusion following anti-VEGF treatment. Additionally, the average size of FD decreased after the loading phase. Although not reaching statistical significance, there was a progressive reduction in the FDa across all rings. Our study highlights a CC FD reduction following the administration of three consecutive faricimab injections. This effect was detected in all rings surrounding the dark halo. These observations suggest a partial CC reperfusion surrounding the MNV, potentially serving as an indicator for disease regression.

Investigating the determinants of iridolenticular contact area: a novel parameter for angle closure

Background/aimsTo identify ocular determinants of iridolenticular contact area (ILCA), a recently introduced swept-source optical coherence tomography (SSOCT) derived parameter, and assess the association between ILCA and angle closure.MethodsIn this population-based...

Assessment of retinal volume in individuals without ocular disorders based on wide-field swept-source optical coherence tomography

PurposeTo evaluate retinal volume in eyes without retinal disease using wide-field swept-source optical coherence tomography (SS-OCT). DesignObservational, cross-sectional design ParticipantsA total of 332 eyes of 166 healthy participants. MethodsThe eyes were imaged with OCT-S1 (Canon) using a protocol centered on the fovea cube scans (20 × 23 mm) of SS-OCT images. Retinal volume (6-mm circle, 6–20-mm ring) and various parameters were evaluated in a multivariate analysis using a generalized estimating equation model. Each quadrant of the macula except for the fovea (1–6 mm in diameter) and peripheral ring (6–20 mm in diameter) was also evaluated. Main Outcome MeasureRetinal volume ResultsIn the multivariate analysis, older age and longer axial length were associated with smaller macular retinal volume, whereas older age and left eye were associated with smaller peripheral retinal volume. The temporal area was significantly smaller than all other areas in the macula (1–6 mm), whereas the inferior area was significantly smaller than all other areas in the peripheral retina (6–20 mm). ConclusionsIn wide-field SS-OCT images, age and left eye are negatively correlated with peripheral retinal volume. The thinnest part of the retinal quadrant differs between the macular and peripheral retinas.

Segmentation and quantitative analysis of optical coherence tomography (OCT) images of laser burned skin based on deep learning

Evaluation of skin recovery is an important step in the treatment of burns. However, conventional methods only observe the surface of the skin and cannot quantify the injury volume. Optical coherence tomography (OCT) is a non-invasive, non-contact, real-time technique. Swept source OCT uses near infrared light and analyzes the intensity of light echo at different depths to generate images from optical interference signals. To quantify the dynamic recovery of skin burns over time, laser induced skin burns in mice were evaluated using deep learning of Swept source OCT images. A laser-induced mouse skin thermal injury model was established in thirty Kunming mice, and OCT images of normal and burned areas of mouse skin were acquired at day 0, day 1, day 3, day 7, and day 14 after laser irradiation. This resulted in 7000 normal and 1400 burn B-scan images which were divided into training, validation, and test sets at 8:1.5:0.5 ratio for the normal data and 8:1:1 for the burn data. Normal images were manually annotated, and the deep learning U-Net model (verified with PSPNe and HRNet models) was used to segment the skin into three layers: the dermal epidermal layer, subcutaneous fat layer, and muscle layer. For the burn images, the models were trained to segment just the damaged area. Three-dimensional reconstruction technology was then used to reconstruct the damaged tissue and calculate the damaged tissue volume. The average IoU value and f-score of the normal tissue layer U-Net segmentation model were 0.876 and 0.934 respectively. The IoU value of the burn area segmentation model reached 0.907 and f-score value reached 0.951. Compared with manual labeling, the U-Net model was faster with higher accuracy for skin stratification. OCT and U-Net segmentation can provide rapid and accurate analysis of tissue changes and clinical guidance in the treatment of burns.

Optical coherence tomography choroidal enhancement using generative deep learning

Spectral-domain optical coherence tomography (SDOCT) is the gold standard of imaging the eye in clinics. Penetration depth with such devices is, however, limited and visualization of the choroid, which is essential for diagnosing chorioretinal disease, remains limited. Whereas swept-source OCT (SSOCT) devices allow for visualization of the choroid these instruments are expensive and availability in praxis is limited. We present an artificial intelligence (AI)-based solution to enhance the visualization of the choroid in OCT scans and allow for quantitative measurements of choroidal metrics using generative deep learning (DL). Synthetically enhanced SDOCT B-scans with improved choroidal visibility were generated, leveraging matching images to learn deep anatomical features during the training. Using a single-center tertiary eye care institution cohort comprising a total of 362 SDOCT-SSOCT paired subjects, we trained our model with 150,784 images from 410 healthy, 192 glaucoma, and 133 diabetic retinopathy eyes. An independent external test dataset of 37,376 images from 146 eyes was deployed to assess the authenticity and quality of the synthetically enhanced SDOCT images. Experts’ ability to differentiate real versus synthetic images was poor (47.5% accuracy). Measurements of choroidal thickness, area, volume, and vascularity index, from the reference SSOCT and synthetically enhanced SDOCT, showed high Pearson’s correlations of 0.97 [95% CI: 0.96–0.98], 0.97 [0.95–0.98], 0.95 [0.92–0.98], and 0.87 [0.83–0.91], with intra-class correlation values of 0.99 [0.98–0.99], 0.98 [0.98–0.99], and 0.95 [0.96–0.98], 0.93 [0.91–0.95], respectively. Thus, our DL generative model successfully generated realistic enhanced SDOCT data that is indistinguishable from SSOCT images providing improved visualization of the choroid. This technology enabled accurate measurements of choroidal metrics previously limited by the imaging depth constraints of SDOCT. The findings open new possibilities for utilizing affordable SDOCT devices in studying the choroid in both healthy and pathological conditions.

Quantitative evaluation of OCT angiography images in healthy and glaucomatous subjects through a novel approach: exploring inter-image variability.

This study aims to investigate inter-image intra-observer variability of macular, and optic disc (ONH) microvasculature measurements of glaucomatous and normal subjects using Swept-Source Optical Coherence Tomography Angiography (OCT-A) (OCT Topcon ImageNet 6; DRI OCT Triton, Topcon Corporation, JAPAN) - based imaging data analysis and processing with a newly made quantitative approach. A total of 20 glaucomatous and 20 healthy eyes underwent three OCT-A scanning of the ONH and macula. Macular and papillary and peripapillary vascular networks were calculated. For each eye, eighteen scans were analyzed using a novel approach: custom MATLAB 2021b scripts were employed for imaging analyses. Grayscale distribution was performed using the histcounts MATLAB function with 51 bins. For all layers, the vascular layer coefficient of variation (vl CoV) of the three measures were performed. The vl CoV difference between the two groups was analyzed by Student t-test. In glaucomatous eyes, the vl CoV ranged from 4.49% to 8.54%, while in the control group from 3.58% to 8.32%. Both groups exhibited higher CoVs when assessing the optic disc. The papillary and macular microvasculature reproducibility was comparable between groups. Utilizing Swept-Source OCT-A images our study has identified an easy and reproducible method that appears to be fast and can assist physicians in assessing macular and ONH perfusion with less inter-image variability, particularly in the 70 μm superficial area of the optic disc. The high reliability obtained suggested that this method could be useful as early clinical biomarker.

Rediscovering Age-Related Macular Degeneration with Swept-Source OCT Imaging: The 2022 Charles L. Schepens, MD, Lecture

Swept-source optical coherence tomography angiography (SS-OCTA) scans of eyes with age-related macular degeneration (AMD) were used to replace color, autofluorescence, infrared reflectance, and dye-based fundus angiographic imaging for the diagnosis and staging of AMD. Through the use of different algorithms with the SS-OCTA scans, both structural and angiographic information can be viewed and assessed using both cross-sectional and en face imaging strategies. Presented at the 2022 Charles L. Schepens, MD, Lecture at the American Academy of Ophthalmology Retina Subspecialty Day, Chicago, Illinois, on September 30, 2022 PARTICIPANTS: Patients with AMD METHODS: Review of published literature and ongoing clinical research using SS-OCTA imaging in AMD. SS-OCTA imaging of AMD at different stages of disease progression. Volumetric SS-OCTA dense raster scans were used to diagnose and stage both exudative and nonexudative AMD. In eyes with nonexudative AMD, a single SS-OCTA scan was used to detect and measure structural features in the macula such as the area and volume of both typical soft drusen and calcified drusen, the presence and location of hyperreflective foci, the presence of reticular pseudodrusen, also known as subretinal drusenoid deposits, the thickness of the outer retinal layer, the presence and thickness of basal laminar deposits, the presence and area of persistent choroidal hypertransmission defects, and the presence of treatment-naïve nonexudative macular neovascularization. In eyes with exudative AMD, the same SS-OCTA scan pattern was used to detect and measure the presence of macular fluid, the presence and type of macular neovascularization, and the response of exudation to treatment with vascular endothelial growth factor inhibitors. In addition, the same scan pattern was used to quantitate choriocapillaris (CC) perfusion, CC thickness, choroidal thickness, and the vascularity of the choroid. Compared with using several different instruments to perform multimodal imaging, a single SS-OCTA scan provides a convenient, comfortable, and comprehensive approach for obtaining qualitative and quantitative anatomic and angiographic information to monitor the onset, progression, and response to therapies in both nonexudative and exudative AMD.

Association between albuminuria and retinal microvascular parameters measured with swept-source optical coherence tomography angiography in patients with diabetic retinopathy.

To evaluate the relationship between urine albumin excretion (UAE) and retinal microvascular parameters assessed using swept-source optical coherence tomography angiography (SS-OCTA) in patients with diabetic retinopathy (DR). This retrospective cross-sectional study included 180 patients with diabetes and 50 age-matched controls. Patients with diabetes were grouped according to the five-stage DR severity, combined with the presence of albuminuria. All subjects underwent 12×12mm2 field SS-OCTA. The foveal avascular zone metrics, vessel density, and capillary nonperfusion area (NPA) were quantified using a semi-automatic software algorithm on three different rectangular fields (3×3 mm2, 6×6 mm2, and 10×10 mm2). The correlations between albuminuria and the four OCTA parameters were analyzed. A total of 105 subjects had normal UAE, and 75 subjects had albuminuria. Of the 102 subjects whose DR severity was higher than mild non-proliferative DR (NPDR), capillary NPA on the 3×3 mm2, 6×6 mm2, and 10×10 mm2 fields was significantly larger in the albuminuria group. None of the OCTA parameters were significantly different between the two groups in subjects with mild NPDR or without DR. Multiple logistic regression analysis showed that an increase in NPA in the 6×6 mm2 and 10×10 mm2 fields was a significant risk factor for the presence of albuminuria (odds ratio = 1.92 and 1.35). An increase in capillary NPA was independently associated with albuminuria in patients with clinically significant DR levels. SS-OCTA imaging can be a useful marker for the early detection of diabetic nephropathy.

Vascular changes of the choroid and their correlations with visual acuity in diabetic retinopathy.

To investigate changes in the choroidal vasculature and their correlations with visual acuity in diabetic retinopathy (DR). The cohort was composed of 225 eyes from 225 subjects, including 60 eyes from 60 subjects with healthy control, 55 eyes from 55 subjects without DR, 46 eyes from 46 subjects with nonproliferative diabetic retinopathy (NPDR), 21 eyes from 21 subjects with proliferative diabetic retinopathy (PDR), and 43 eyes from 43 subjects with clinically significant macular edema (CSME). Swept-source optical coherence tomography (SS-OCT) was used to image the eyes with a 12-mm radial line scan protocol. The parameters for 6-mm diameters of region centered on the macular fovea were analyzed. Initially, a custom deep learning algorithm based on a modified residual U-Net architecture was utilized for choroidal boundary segmentation. Subsequently, the SS-OCT image was binarized and the Niblack-based automatic local threshold algorithm was employed to calibrate subfoveal choroidal thickness (SFCT), luminal area (LA), and stromal area (SA) by determining the distance between the two boundaries. Finally, the ratio of LA and total choroidal area (SA + LA) was defined as the choroidal vascularity index (CVI). The choroidal parameters in five groups were compared, and correlations of the choroidal parameters with age, gender, duration of diabetes mellitus (DM), glycated hemoglobin (HbA1c), fasting blood sugar, SFCT and best-corrected visual acuity (BCVA) were analyzed. The CVI, SFCT, LA, and SA values of patients with DR were found to be significantly lower compared to both healthy patients and patients without DR (P< 0.05). The SFCT was significantly higher in NPDR group compared to the No DR group (P < 0.001). Additionally, the SFCT was lower in the PDR group compared to the NPDR group (P = 0.014). Furthermore, there was a gradual decrease in CVI with progression of diabetic retinopathy, reaching its lowest value in the PDR group. However, the CVI of the CSME group exhibited a marginally closer proximity to that of the NPDR group. The multivariate regression analysis revealed a positive correlation between CVI and the duration of DM as well as LA (P < 0.05). The results of both univariate and multivariate regression analyses demonstrated a significant positive correlation between CVI and BCVA (P = 0.003). Choroidal vascular alterations, especially decreased CVI, occurred in patients with DR. The CVI decreased with duration of DM and was correlated with visual impairment, indicating that the CVI might be a reliable imaging biomarker to monitor the progression of DR.

Clinical and optical coherence tomography biomarkers as prognostic factors in dexamethasone intravitreal implant for diabetic macular edema.

Aim of the study was to evaluate the efficacy of dexamethasone (DEX) 0.7 mg intravitreal implant in patients with diabetic macular edema (DME) and serous retinal detachment (SRD), and to study the prognostic factors on a follow up of 12 months. Forty eyes of twenty- six patients with centre involving DME and SRD, who underwent DEX implant, were enrolled. Best-corrected visual acuity (BCVA), Swept source OCT imaging and intraocular pressure were evaluated. Central macular thickness (CMT), vitreomacular adhesion (VMA), disorganization of retinal inner layers (DRILs), hyperreflective dots (HRD), SRD and ellipsoid zone (EZ) disruption were included in the analysis at baseline and 12 months after implant. According to our parametric analysis, at 12 months, BVCA improvement from 48.6 ± 23.4 letters to 53.3 ± 24.5 letters was statistically significant (p = 0.04), CMT decreased from 460 ± 99.52 μm to 322.9 ± 117 μm. The presence at baseline of VMA (p = 0.01), EZ disruption (p = 0.03) and DRILs (p = 0.04), were associated with poor BCVA improvement at the end of follow-up. In conclusion, OCT biomarkers can be considered significant prognostic factors for treatment outcome in patients with DME undergoing DEX intravitreal implant.

PEG-coated NaYF4:Tm3+/Yb3+ upconversion nanoparticles for OCT image contrast enhancer, optical thermometry, and security applications

Polyethylene glycol (PEG) coated NaYF4:Tm3+/Yb3+ upconversion nanoparticles (UCNPs) were synthesized, and their usefulness in improving image contrast in Swept source optical coherence tomography (SS-OCT) and photo-thermal (PT-OCT) imaging was assessed. Synthesized UCNPs have shown biocompatibility with a cell survival rate of more than 90% after 24 h of incubation of HeLa cells. Prepared particles have shown intense blue upconversion emission along with a photo-thermal conversion efficiency of 30.4%. Leveraging these UCNPs, enhancements in image quality were achieved in both SS-OCT and PT-OCT imaging modalities, manifesting improved scattering coefficients and contrast-to-noise ratios. Temperature-dependent upconversion emission spectra were used to assess temperature sensing and thermal sensitivity of 107×10-3 K-1 at 300 K is obtained for the synthesized nanoparticles. Additionally, these UCNPs have demonstrated utility in latent finger-marks detection and anti-counterfeiting applications.

Early regional changes in retina and choroid of chicks following monocular hemifield form deprivation

To investigate regional changes in the chick retina and choroid after hemifield form deprivation (HFD). Ten chicks were randomly and equally divided into a temporal retinal deprivation (TRD) and nasal retinal deprivation (NRD) group. HFD was induced with half-lateral translucent plastic goggles in the right eye; the left eye was kept untreated. Swept-source optical coherence tomography (SS-OCT) images obtained at 0, 3, and 72 hours (h) were analyzed using customized software. After 72 h of TRD, the retinal thickness (RT) of the treated eyes was significantly less than that of the fellow eyes in the temporal (P = 0.034) rather than the nasal (P = 0.083) region. In the NRD group, the RT of the treated eyes was thinner in both the nasal and temporal regions than that of the fellow eyes (P < 0.01). The RT alterations were more pronounced in the temporal (Δ = −16.86 ± 7.14 μm) than in the nasal (Δ = −13.44 ± 4.83 μm) region after 72-h TRD (P = 0.036), whereas the opposite was observed in the NRD group (P = 0.008). The choroidal thickness (ChT) of the treated eyes was less in both the nasal and temporal regions than that of the fellow eyes in both groups after 72-h treatment (P < 0.01). The ChT alterations were more pronounced in the temporal (Δ = −2.48 ± 8.95 μm) than in the nasal (Δ = 23.65 ± 13.58 μm) region after 72-h TRD (P = 0.021), whereas the NRD group showed the opposite effect (P = 0.019). HFD in chicks can lead to retinal and choroidal thinning in the corresponding regions.

Diagnostic performance of wide-field optical coherence tomography angiography for high myopic glaucoma

Diagnosing and monitoring glaucoma in high myopic (HM) eyes are becoming very important; however, it is challenging to diagnose this condition. This study aimed to evaluate the diagnostic ability of wide-field optical coherence tomography angiography (WF-OCTA) maps for the detection of glaucomatous damage in eyes with HM and to compare the diagnostic ability of WF-OCTA maps with that of conventional imaging approaches, including swept-source optical coherence tomography (SS-OCT) wide-field maps. In this retrospective observational study, a total 62 HM-healthy eyes and 140 HM eyes with open-angle glaucoma were included. Patients underwent a comprehensive ocular examination, including SS-OCT wide-field and 12 × 12 WF-OCTA scans. The WF-OCTA map represents the peripapillary and macular superficial vascular density maps. Glaucoma specialists determined the presence of glaucomatous damage in HM eyes by reading the WF-OCTA map and comparing its sensitivity and specificity with those of conventional SS-OCT images. The sensitivity and specificity of 12 × 12 WF-OCTA scans for HM-glaucoma diagnosis were 87.28% and 86.94%, respectively, while, the sensitivity and specificity of SS-OCT wide-field maps for HM-glaucoma diagnosis were 87.49% and 80.51%, respectively. The specificity of the WF-OCTA map was significantly higher than that of the SS-OCT wide-field map (p < 0.05). The sensitivity of the WF-OCTA map was comparable with that of the SS-OCT wide-field map (p = 0.078). The WF-OCTA map showed good diagnostic ability for discriminating HM-glaucomatous eyes from HM-healthy eyes. As a complementary method to an alternative imaging modality, WF-OCTA mapping can be a useful tool for the detection of HM glaucoma.

Enhanced choroidal thickness, total choroidal area and choroidal vascularity index from deep‐learning generated OCT images

Aims/Purpose: Our goal is to enhance the visualization of the choroid in clinical standard spectral‐domain OCT (SDOCT) scans using a deep‐learning (DL) approach that uses matching swept‐source OCT (SSOCT). We aim to improve the measurement of the sub‐foveal choroidal thickness (SFCT), total choroidal area (TCA), and choroidal vascularity index (CVI) in SDOCT images.Methods: A total of 105 350 SDOCT and SSOCT B‐scan images (Zeiss Cirrus 5000 and Zeiss PlexElite) were used to develop the DL model. The data set included B‐scans from healthy (238 eye pairs from 155 patients) and glaucoma (192 eye pairs from 122 patients) subjects. The DL model learned deep anatomical features from SSOCT scans and generated enhanced SDOCT images. The peak signal‐to‐noise ratio (PSNR) and structural similarity index metric (SSIM) were used to assess the quality of generated images. In addition, we compared the anatomical parameters derived from the generated and ground‐truth SSOCT images, including SVCT, TCA and CVI values.Results: We tested our method using 20 580 B‐scan image pairs from 84 eyes. The DL‐generated images effectively preserved the anatomical structure of the retina layers and improved the visualization of the choroid. The enhanced SDOCT images had higher image quality than the original SDOCT images, as demonstrated by the higher PSNR (31 dB vs. 18 dB) and SSIM values (3.4 times higher SSIM than the original SDOCT images). SVCT, TCA, and CVI measurements from the DL‐generated SDOCT images showed strong correlations with corresponding measurements using SSOCT with high Pearson's coefficients (0.93, 0.99, and 0.93), high intra‐class correlation indices (0.96, 0.99 and 0.96), and high coefficient of determination r2 values (0.85, 0.98 and 0.86).Conclusions: Our DL model enhances the visibility of the choroid in images, surpassing the capabilities of standard clinical SDOCT images. As a result, accurate measurement of SVCT, TCA and CVI, which were previously limited due to imaging depth constraints of SDOCT, becomes possible. This technology opens up new possibilities for utilizing affordable SDOCT devices to study the choroid in healthy and pathological conditions.

Evaluating the diagnostic performance with neurovascular segregation of the retinal nerve fibre layer in glaucoma

Aims/Purpose: To evaluate the diagnostic performance in detecting eyes with glaucoma by segregating the neuronal and vascular components in circumpapillary optical coherence tomography (OCT) and OCT angiography (OCTA) scans.Methods: In this study, 93 participants with glaucoma were age‐ and gender‐matched with normal controls with no ocular diseases. OCT and OCTA volumetric images of one eye from each participant were acquired using a prototype high resolution swept source OCT imaging system (Zeiss PlexElite) using a 6 mm x 6 mm imaging protocol centered at the optic nerve head. Circumpapillary OCT and OCTA images with a diameter of 3.46 mm were subsequently generated. Information from the circumpapillary and enface OCTA images were used to isolate and segregate the vascular components from the circumpapillary retinal nerve fibre layer (RNFL), which was obtained using a deep learning segmentation approach. Thicknesses of the RNFL with and without the vascular components were measured and diagnostic performance was evaluated using area under the receiving operating characteristic curve (AUC) analysis. Both global and quadrant (superior, inferior, nasal and temporal) measurements around the optic nerve head were considered.Results: Imaging data of one eye from 154 healthy and 143 glaucoma participants were acquired. Using only the global RNFL thickness, the detection of glaucoma achieved an AUC of 0.877 ± 0.021. With the vascular components excluded from the global RNFL thickness, an AUC of 0.890 ± 0.020 was obtained. When the vascular and non‐vascular components of the RNFL in the different quadrants were modelled separately, AUC improved to 0.927 ± 0.015, and was found to be significantly higher than the detection of glaucoma using global measures (p &lt; 0.001).Conclusions: Segregation of vascular and non‐vascular components in the retinal nerve fibre layer led to an improvement in glaucoma detection. Further improvements were observed when the contributions of the components in the RNFL quadrants were modelled separately.

Assessing silver nanoparticle uptake dynamics in young zebrafish using swept source optical coherence tomography

Understanding the uptake and accumulation of nanoparticles in living organisms is crucial for assessing their potential effects on health and the environment. In this study, we employed a Swept Source Optical Coherence Tomography (SSOCT) system to investigate the dynamics of silver nanoparticle (AgNP) uptake during various developmental stages of zebrafish. Silver nanoparticles in the 20 nm range were synthesized and their uptake and accumulation in developing zebrafish embryos were studied over time. Changes in optical attenuation properties observed in SSOCT images allowed identification of nanoparticle uptake and accumulation in the eye, intestine, and gill region of developing zebrafish. The changes were quantified by deriving average local attenuation coefficient values. To validate our findings, inductively-coupled plasma optical emission spectrometry (ICP-OES) analysis was performed.

Deep-learning-based automated measurement of outer retinal layer thickness for use in the assessment of age-related macular degeneration, applicable to both swept-source and spectral-domain OCT imaging.

Effective biomarkers are required for assessing the progression of age-related macular degeneration (AMD), a prevalent and progressive eye disease. This paper presents a deep learning-based automated algorithm, applicable to both swept-source OCT (SS-OCT) and spectral-domain OCT (SD-OCT) scans, for measuring outer retinal layer (ORL) thickness as a surrogate biomarker for outer retinal degeneration, e.g., photoreceptor disruption, to assess AMD progression. The algorithm was developed based on a modified TransUNet model with clinically annotated retinal features manifested in the progression of AMD. The algorithm demonstrates a high accuracy with an intersection of union (IoU) of 0.9698 in the testing dataset for segmenting ORL using both SS-OCT and SD-OCT datasets. The robustness and applicability of the algorithm are indicated by strong correlation (r = 0.9551, P < 0.0001 in the central-fovea 3 mm-circle, and r = 0.9442, P < 0.0001 in the 5 mm-circle) and agreement (the mean bias = 0.5440 um in the 3-mm circle, and 1.392 um in the 5-mm circle) of the ORL thickness measurements between SS-OCT and SD-OCT scans. Comparative analysis reveals significant differences (P < 0.0001) in ORL thickness among 80 normal eyes, 30 intermediate AMD eyes with reticular pseudodrusen, 49 intermediate AMD eyes with drusen, and 40 late AMD eyes with geographic atrophy, highlighting its potential as an independent biomarker for predicting AMD progression. The findings provide valuable insights into the ORL alterations associated with different stages of AMD and emphasize the potential of ORL thickness as a sensitive indicator of AMD severity and progression.

Imaging Artifacts and Quality Evaluation with Ultrawide-Field Swept-Source OCTA in Diabetic Retinopathy

Purpose To evaluate the prevalence and types of artifacts in ultrawide-field swept-source optical coherence tomography angiography (SS-OCTA) scans of diabetic retinopathy (DR) patients. Methods This study was a prospective, observational study conducted from May 2022 to October 2022. Participants comprised individuals with proliferative diabetic retinopathy (PDR), nonproliferative diabetic retinopathy (NPDR), no diabetic retinopathy, and healthy controls. SS-OCTA imaging was performed, and a 5-scan composite with a larger field of view (23.5 mm × 17.5 mm) was captured using built-in software. Two experienced ophthalmologists analyzed the images independently, and the image quality and artifact prevalence were recorded and analyzed. Results The study included 70 eyes (16 with PDR, 24 with NPDR, 12 eyes of diabetic patients without DR, and 18 healthy eyes) in 70 subjects. Imaging artifacts were observed in a high percentage of eyes, with 98.57% of eyes presenting at least one type of artifact. A significant proportion of eyes (58.57%) exhibited a severe degree of artifacts. The most prevalent artifacts were loss of signal in 63 eyes (90%) and displacement artifact and masking artifact in 43 eyes (61.4%). Patients with more severe stages of DR had higher artifact scores (p < 0.05). Multivariate regression analysis indicated that DR severity was the most important factor influencing artifact scores (p < 0.05). Conclusions In OCTA photos, various artifacts arise at different frequencies. It is crucial to qualitatively evaluate the images to ensure their quality. The results demonstrate that DR severity has a significant correlation with artifact scores.

Integrity of the Hyperreflective Layer in the Inner Choroid in Eyes with Drusen.

This study aimed to compare the integrity of the hyperreflective layer of the inner choroid in eyes with and without drusen. Swept-source optical coherence tomography images of patients with drusen and normal controls were reviewed. Using a line plot of ImageJ, choroidal reflectivity was measured at the subfovea, and the integrity of the hyperreflective layer of the inner choroid was determined. In total, 63 eyes with drusen and 30 control eyes without drusen were included. The integrity of the hyperreflective layer of the inner choroid was preserved in 81.0% of eyes with drusen and 93.3% of normal controls. The proportion of eyes with the hyperreflective layer did not differ between eyes with and without drusen. Of the 63 subjects with drusen, this hyperreflective layer was observed in all 28 eyes (100%) with pachydrusen but only in 68.6% of the 35 eyes with soft drusen, and its prevalence was significantly different (P = 0.001). The prevalence of the hyperreflective layer between the choriocapillaris and medium or large choroidal vessels in eyes with soft drusen differed from that in eyes with pachydrusen. These findings support the suggestion that changes within the choroidal stroma may be involved in the pathogenesis of age-related macular degeneration.

Age-related changes in geometry and transparency of human crystalline lens revealed by optical signal discontinuity zones in swept-source OCT images

BackgroundThe shape and microstructure of the human crystalline lens alter with ageing, and this has an effect on the optical properties of the eye. The aim of this study was to characterise the age-related differences in the morphology and transparency of the eye lenses of healthy subjects through the optical signal discontinuity (OSD) zones in optical coherence tomography (OCT) images. We also investigated the association of those changes with the optical quality of the eye and visual function.MethodsOCT images of the anterior segment of 49 eyes of subjects (9–78 years) were acquired, and the OSD zones (nucleus, C1–C4 cortical zones) were identified. Central thickness, curvature and optical density were measured. The eye’s optical quality was evaluated by the objective scatter index (OSI). Contrast sensitivity and visual acuity tests were performed. The correlation between extracted parameters and age was assessed.ResultsThe increase in lens thickness with age was dominated by the thickening of the cortical zone C3 (0.0146 mm/year). The curvature radii of the anterior lens surface and both anterior and posterior nucleo-cortical interfaces decreased with age (− 0.053 mm/year, − 0.013 mm/year and − 0.006 mm/year, respectively), and no change was observed for the posterior lens radius. OCT-based densitometry revealed significant correlations with age for all zones except for C1β, and the highest increase in density was in the C2–C4 zones (R = 0.45, 0.74, 0.56, respectively, P < 0.001). Increase in OSI was associated with the degradation of visual function.ConclusionsOCT enables the identification of OSD zones of the crystalline lens. The most significant age-related changes occur in the C3 zone as it thickens with age at a faster rate and becomes more opaque than other OSD zones. The changes are associated with optical quality deterioration and reduction of visual performance. These findings contribute to a better understanding of the structure–function relationship of the ageing lens and offer insights into both pathological and aging alterations.