Structural Optical Coherence Tomography Research Articles

Quantification of elastic anisotropy of human skin in vivo with dynamic optical coherence elastography and polarization-sensitive OCT

The complex structure of skin ensures a broad range of biological functions. The loss of a large skin area due to trauma or disease usually requires reconstructive surgery that often involves grafting or flapping. The clinical need for non-contact objective measurements of skin elasticity is necessary to guide grafting procedures to minimize complications such as secondary contracture or hypertrophic scars. Here, we report a non-contact and non-invasive method combining acoustic micro-tapping optical coherence elastography (AμT-OCE) with polarization-sensitive (PS-) optical coherence tomography (OCT) to quantify anisotropic elastic properties of skin. We show that all three elastic constants that define skin’s anisotropic elastic deformation and the orientation of collagen fibers in the dermis can be determined from propagating elastic waves over the skin surface. Measurements were performed on healthy volunteers in vivo. A nearly incompressible transverse isotropic model of skin elasticity was used to reconstruct the moduli from experimental data after being validated in extensive numerical simulations. Finally, we demonstrate that combining several OCT modalities (structural OCT, OCT angiography, PS-OCT, and AμT-OCE) may provide rich information about skin and demonstrate the potential for complex characterization of scar.

Optical Coherence Tomography Angiographic Evaluation of Macular Vessel Density in Diabetic Macular Edema After Intravitreal Dexamethasone Implants: A Prospective Interventional Trial.

The goal of this study was to assess macular vascular density evolution, macular thickness, and functional outcomes after intravitreal dexamethasone implants for diabetic macular edema. Vascular density was evaluated with optical coherence tomography (OCT) angiography in 21 eyes. Macular thickness was evaluated with structural OCT. Visual acuity and contrast sensitivity were evaluated before and after treatment, and these functional outcomes were analyzed for association with anatomic outcomes. Macular vessel density in the superficial capillary plexus was evaluated with OCT angiography and quantified in areas with no fluid, allowing a more accurate measurement and eliminating the segmentation bias in areas with intra-retinal fluid. Such a methodology was possible by positioning the scans only in areas with no fluid before and after the implant. The absence of fluid in these areas was confirmed by three experienced evaluators using both the B-scan and the en face. Visual acuity and contrast sensitivity were evaluated before and after treatment, and these functional outcomes were analyzed for association with anatomic outcomes. At 30, 60, and 90 days after implantation, there was improvement in macular perfusion in areas without fluid after intravitreal dexamethasone implantation, accompanied by reduced macular thickness and improved visual acuity (P < .001). However, there was no improvement in contrast sensitivity after treatment. Improved macular perfusion after treatment with intravitreal dexamethasone implantation may be associated with modulation of leukostasis, when the release of cytokines leads to capillary endothelial damage and obstruction of the micro-vasculature, leading to impaired capillary perfusion and ischemic damage. Despite the anatomical and functional findings demonstrated, further studies are needed to prove the relationship between the inflammatory mechanisms of diabetic macular edema and its relationship with macular perfusion and functional aspects. [Ophthalmic Surg Lasers Imaging Retina 2023;54(3):174-182.].

Optical Coherence Tomography Angiography Demonstrates Strain and Volume Effects on Optic Disk and Peripapillary Vasculature Caused by Horizontal Duction

Purpose The optic nerve mechanically loads the eye during ocular rotation, thus altering the configuration of the disk and peripapillary tissues. We used optical coherence tomography (OCT) angiography (OCTA) to investigate mechanical strains and volume changes in disk and peripapillary blood vessels during horizontal duction. Methods Structural OCT and OCTA were performed centered on optic disks; imaging was repeated in central gaze, and in 30° ab- and adduction. By an algorithm employing point-set registration of 3 D features, we developed a novel approach for measuring disk strains, and strains and volumes of the blood vessels associated with horizontal duction. Repeatability was demonstrated in each gaze position. Results 19 eyes of 10 healthy adults of average age 37 ± 15 (standard deviation, SD) years were imaged. The method was validated by demonstrating numerically consistent vascular volumes and strains for repeated imaging under identical conditions. Compared with central gaze, vascular volume increased by 5.2 ± 4.1% in adduction. Adduction and abduction caused strains of 3.0 ± 1.6% and 2.6 ± 1.8% in the optic disk, whereas blood vessels showed greater strains of 8.1 ± 1.3% and 8.2 ± 1.7%. Decomposition of strain components depending on directionality and regions demonstrated that adduction induces significant net tensile strains, suggesting traction exerted by the optic nerve. The decomposition also showed that nasotemporal compressive strains are larger in temporal hemidisks than nasal hemidisks. The Bruch’s membrane opening was significantly compressed horizontally in adduction by 1.1% (p = .009). Conclusion This novel analysis combining structural OCT and OCTA demonstrates that optic disk compression during adduction is associated with disk and vascular strains much larger than reported for intraocular pressure elevation and pulsatile perfusion, as well as compressing the disk and increasing peripapillary vascular volume. These changes may be relevant to the pathogenesis of optic nerve and retinal vascular disorders.

Analysis of the pachychoroid phenotype in an Asian population: methodology and baseline study population characteristics

AimTo describe the clinical characteristics in a cohort of patients with the pachychoroid phenotype and to evaluate the association of ocular and systemic factors with type of complications observed.MethodsWe report...

Automated large-scale prediction of exudative AMD progression using machine-read OCT biomarkers.

Age-related Macular Degeneration (AMD) is a major cause of irreversible vision loss in individuals over 55 years old in the United States. One of the late-stage manifestations of AMD, and a major cause of vision loss, is the development of exudative macular neovascularization (MNV). Optical Coherence Tomography (OCT) is the gold standard to identify fluid at different levels within the retina. The presence of fluid is considered the hallmark to define the presence of disease activity. Anti-vascular growth factor (anti-VEGF) injections can be used to treat exudative MNV. However, given the limitations of anti-VEGF treatment, as burdensome need for frequent visits and repeated injections to sustain efficacy, limited durability of the treatment, poor or no response, there is a great interest in detecting early biomarkers associated with a higher risk for AMD progression to exudative forms in order to optimize the design of early intervention clinical trials. The annotation of structural biomarkers on optical coherence tomography (OCT) B-scans is a laborious, complex and time-consuming process, and discrepancies between human graders can introduce variability into this assessment. To address this issue, a deep-learning model (SLIVER-net) was proposed, which could identify AMD biomarkers on structural OCT volumes with high precision and without human supervision. However, the validation was performed on a small dataset, and the true predictive power of these detected biomarkers in the context of a large cohort has not been evaluated. In this retrospective cohort study, we perform the largest-scale validation of these biomarkers to date. We also assess how these features combined with other EHR data (demographics, comorbidities, etc) affect and/or improve the prediction performance relative to known factors. Our hypothesis is that these biomarkers can be identified by a machine learning algorithm without human supervision, in a way that they preserve their predictive nature. The way we test this hypothesis is by building several machine learning models utilizing these machine-read biomarkers and assessing their added predictive power. We found that not only can we show that the machine-read OCT B-scan biomarkers are predictive of AMD progression, we also observe that our proposed combined OCT and EHR data-based algorithm outperforms the state-of-the-art solution in clinically relevant metrics and provides actionable information which has the potential to improve patient care. In addition, it provides a framework for automated large-scale processing of OCT volumes, making it possible to analyze vast archives without human supervision.

Nascent Geographic Atrophy as a Predictor of Type 3 Macular Neovascularization Development

To investigate the association of nascent geographic atrophy (GA) preceding the development of exudative type 3 macular neovascularization (MNV) in patients with age-related macular degeneration (AMD). Retrospective longitudinal study. AMD patients diagnosed with treatment-naïve exudative type 3 MNV in one or both eyes were evaluated. Inclusion criteria included serial tracked structural optical coherence tomography (OCT) examinations for ≥ 2 years prior to the detection of exudative type 3 MNV. Clinical characteristics and retinal imaging including structural OCT at baseline and at each follow-up examination were analyzed. Eyes showing the presence of nascent GA during the follow-up were selected for analysis of prevalence, and clinical characteristics at the site of subsequent type 3 MNV development. Description of prevalence and clinical characteristics of nascent GA at the site of subsequent type 3 MNV development. Ninety-seven eyes affected by type 3 MNV meeting inclusion criteria were analyzed. Of 97 eyes (71 patients), 22 eyes of 21 patients (mean age 82±9 years) showed nascent GA preceding exudative type 3 MNV. The observed prevalence of nascent GA preceding exudative type 3 MNV was 22.7% (95% CI: 14.4-31.0%). Exudative Type 3 MNV developed a mean of 9±6 months following detection of nascent GA. The presence of reticular pseudodrusen in the study eye did not significantly influence the timing of exudative type 3 MNV development after the observation of nascent GA (p>0.1 in all analyses). Reduced BCVA was recorded at the exudative type 3 stage in comparison to the nascent GA stage (p=0.003). As nascent GA may precede the development of exudative type 3 MNV, the detection of nascent GA in eyes with AMD may warrant closer surveillance in order to identify early exudative type 3 MNV warranting treatment.

Characterizing macular edema in retinitis pigmentosa through a combined structural and microvascular optical coherence tomography investigation

The aim of the study was to characterize macular edema (ME) in retinitis pigmentosa (RP) by means of quantitative optical coherence tomography (OCT)-based imaging. The study was designed as observational, prospective case series, with 1-year follow-up. All RP patients underwent complete ophthalmologic assessment, including structural OCT, OCT angiography, and microperimetry (MP). The primary outcome was the characterization through quantitative OCT-based imaging of RP eyes complicated by ME. A total of 68 RP patients’ eyes (68 patients) and 68 eyes of 68 healthy controls were recruited. Mean BCVA was 0.14 ± 0.17 LogMAR at baseline and 0.18 ± 0.23 LogMAR at 1-year follow-up (p > 0.05). Thirty-four eyes (17 patients; 25%) showed ME, with a mean ME duration of 8 ± 2 months. Most of the eyes were characterized by recurrent ME. The ME was mainly localized in the inner nuclear layer in all eyes. LogMAR BCVA was similar in all RP eyes, whether with or without ME, although those with ME were associated with higher vessel density values, as well as thicker choroidal layers, than those without ME. In conclusion, the inner retina is closely involved in the pathogenesis of ME. The impairment of retinal-choroidal exchanges and Müller cell disruption might be a major pathogenic factor leading to the onset of ME in RP.

BENIGN FOVEAL DEPIGMENTATION: A MULTIMODAL IMAGING INVESTIGATION.

To describe the multimodal imaging characteristics of benign foveal depigmentation. The study was designed as prospective observational case series. Patients with benign foveal depigmentation were prospectively investigated by means of multimodal imaging, including blue-light and near-infrared fundus autofluorescence, optical coherence tomography (OCT), OCT angiography, color testing, microperimetry, and electrophysiology. The main outcome measures were vessel density and retinal pigment epithelium (RPE)/photoreceptor complex OCT reflectivity. Overall, 4 patients were identified, with bilateral and unilateral involvement in 1 case and 3 cases, respectively. Fundus autofluorescence provided variable results, showing more impairment on near-infrared fundus autofluorescence. Structural OCT revealed slight attenuation of the outer retinal bands in the area affected by benign foveal depigmentation, associated with choroidal hypertransmission, whereas enface OCT better delineated the attenuation of the reflectivity signal. The mean reflectivity intensity of RPE/photoreceptor complex was statistically significantly reduced in patients with respect to control subjects in the benign foveal depigmentation area. Optical coherence tomography angiography, color testing, microperimetry, electrooculogram, and electroretinogram findings were normal. Benign foveal depigmentation may represent a focal RPE disease. The limited alterations within the RPE band, as visualized on enface OCT and confirmed on near-infrared fundus autofluorescence, suggest an impairment in melanin production or distribution within the RPE cells.

Artificial Intelligence for the Diagnosis and Screening of Retinal Diseases

Artificial intelligence (AI) is becoming established as a new method for analysing ophthalmological data, and unveiling new clinical and pathogenic insights into retinal diseases. AI-based algorithms are largely employed in the field of the most prevalent retinal diseases, including diabetic retinopathy, age-related macular degeneration and myopia. Several research groups are also testing AI in other retinal diseases, including inherited retinal dystrophies, retinopathy of prematurity, central serous chorioretinopathy and retinal vein occlusion. AI models are mainly used in screening of the fundus and structural optical coherence tomography images. However, more advanced methodologies are under investigation to extract clinically relevant information regarding the biomarkers of disease activity and outcome measures. AI is a powerful tool for increasing the amount of information obtained in clinical and research contexts. However, many issues still need addressing, including the resulting high demand for technology and resources, and the need for very large databases. Moreover, several ethical issues require debate, and specific rules are needed to govern the use of AI algorithms and check the quality of the analysed data. This article reviews the current use of AI in retinal diseases, unmet needs and future perspectives.

Artificial intelligence and glaucoma progression

Detection of progression in glaucoma is crucial to avoid visual impairment and blindness. Throughout the clinical course of the disease, glaucoma patients can present very different trajectories, as some patients may remain stable using single eye drops whereas other patients may require surgical procedures to control the disease. Thus, the decision of intensifying a treatment by adding new eye drops or performing a glaucoma surgery need to rely on precise data of true progression ofthe disease. In addition, assessing the velocity of progression can help to identify rapid progressors that are more prone to develop functional impairment. In clinical practice, we use both structural (retinography and optical coherence tomography) and functional (visual field) measurements, along with clinic-demographical data to evaluate if the patient is progressing. However, in some patients the correlation between structural and functional exams makes the detection of progression a challenge. Currently we are facing a growing use of artificial intelligence in medicine with the application of complex algorithms such as deep learning models. In this review, we summarize the findings from recent studies that investigated the use of artificial intelligence in detecting glaucoma progression.

Deep Capillary Plexus Features in Acute Macular Neuroretinopathy: Novel Insights Based on the Anatomy of Henle Fiber Layer.

The purpose of this study was to identify a precise location of deep capillary plexus (DCP) injury in acute macular neuroretinopathy (AMN) lesions using multimodal imaging. En face structural optical coherence tomography (OCT) images were manually segmented to delineate outer retinal AMN lesions involving the ellipsoid zone and interdigitation zone. AMN lesion centroid was calculated, and image distortion was applied to correct for Henle fiber layer (HFL) length and orientation. The resulting image was registered with the corresponding en face OCT angiography (OCTA) image segmented at the DCP and structural OCT volume before grading for vascular and structural features, respectively. Thirty-nine AMN lesions from 16 eyes (11 female patients, mean age 34 ± 4 years) were analyzed. After correcting for HFL anatomy, in 62% of AMN lesions, the centroid co-localized with a capillary vortex (pattern 1); flow defects were detected in 33% of lesions (pattern 2); and in 5% of lesions no specific pattern could be identified (pattern 3). The detection of a specific pattern increased after correcting the projection of AMN lesion for HFL anatomy (28% vs. 5%, P = 0.04). Outer nuclear layer thickness was lower in the centroid area in 10 (29%) AMN lesions from 6 patients, all corresponding to lesions fitting pattern 2 (r = 0.78, P < 0.001). AMN lesions might be a result of DCP impairment at the level of the capillary vortex or draining venule. In eyes with AMN, the location of outer retinal changes associated with DCP ischemia appears to be influenced by the length and orientation of HFL.

Individual vs. combined imaging modalities for diagnosing neovascular central serous chorioretinopathy.

To assess the diagnostic accuracy of individual and combined imaging modalities compared with multimodal imaging for the detection of choroidal neovascularization (CNV) in central serous chorioretinopathy (CSC). We analyzed patients with CSC with and without CNV who had indocyanine green angiography (ICGA), structural optical coherence tomography (OCT), and OCT angiography (OCTA) obtained on the same day. The presence of CNV was determined using multimodal imaging by a senior retina specialist (i.e., diagnostic reference). Individual and combined (i.e., ICGA + structural OCT) imaging modalities were then graded by two expert readers for the presence of CNV. Sensitivity, specificity, positive (PPV), and negative (NPV) predictive values were computed for individual and combined imaging modalities relative to the diagnostic reference. CNV was detected in 17 eyes in 17 out of 33 CSC patients according to the reference standard. Using ICGA, the identification of CNV had a sensitivity of 66.7%, specificity of 66.7%, PPV of 70.6%, and NPV of 62.5%. Structural OCT had the following diagnostic accuracy values: 83.3% of sensitivity, 53.3% of specificity, 68.1% of PPV, and 72.7% of NPV. Using OCTA, CNV was graded to be present with a sensitivity of 77.8%, specificity of 86.7%, PPV of 87.5%, and NPV of 76.5%. The combination of ICGA and structural OCT granted the identification of CNV with a sensitivity of 83.3%, specificity of 86.7%, PPV of 88.2%, and NPV of 81.3%. OCTA has an elevated diagnostic accuracy in identifying CSC-associated CNV, though a combination of ICGA and structural OCT has a comparable diagnostic efficiency.

Visual Outcomes and Optical Coherence Tomography Biomarkers of Vision Improvement in Patients With Leber Hereditary Optic Neuropathy Treated With Idebenone

To assess the relationship of demographics, clinical characteristics and structural optical coherence tomography (OCT) findings to long-term visual outcomes in patients with Leber hereditary optic neuropathy (LHON) treated with idebenone. Retrospective, interventional, noncomparative clinical cohort study. In this study, a total of 17 participants (34 eyes) with LHON treated with idebenone therapy within 1 year after disease onset and 2 years (24 months) of regular follow-ups were retrospectively enrolled. At baseline, structural OCT volume scans of the macula and optic nerve were reviewed to measure metrics reflecting neuronal loss (ie, macular ganglion cell and inner plexiform layer [GC-IPL] and peripapillary retinal nerve fiber layer [RNFL] thicknesses). Stepwise multiple regression analyses were computed to assess associations between final best-corrected visual acuity (BCVA) at 2 years and change in BCVA from baseline at 2 years as dependent variables with demographics, clinical characteristics, and OCT metrics at baseline (visit before the initiation of treatment). The BCVA was 1.6±0.8 logMAR (Snellen VA of ∼20/800) at baseline (visit before the initiation of treatment) and 1.0±0.7 logMAR (Snellen VA of 20/200) at the 2-year follow-up visit (P < .0001). Mean±SD change in BCVA from baseline at 2 years was -51.9%±35.9%. In multivariable analysis, the strongest associations with final BCVA were with baseline BCVA (P=.012), superior macular GC-IPL thickness (P=.044), superotemporal macular GC-IPL thickness (P=.010), and inferotemporal macular GC-IPL thickness (P=.015). Similarly, the strongest associations with delta BCVA were with superior macular GC-IPL thickness (P=.045), superotemporal macular GC-IPL thickness (P=.047), and inferotemporal macular GC-IPL thickness (P=.030). We identified OCT biomarkers associated with long-term (ie, 2-year) visual outcomes in patients with LHON treated with idebenone therapy in the first year after disease onset. Thinning of the GC-IPL in the superior and temporal parafoveal regions was associated with worse long-term visual outcomes in these patients.

Characterization of Hyperreflective Dots by Structural and Angiographic Optical Coherence Tomography in Patients with Diabetic Retinopathy and Healthy Subjects.

Hyperreflective dots are a common but highly variable feature of optical coherence tomography (OCT) scans of the retina. We studied the spatial characteristics and perfusion of hyperreflective dots using both structural and angiographic OCT B-scans of the macula in 16 eyes in 8 healthy subjects and 8 patients with diabetic retinopathy without macular edema. Hyperreflective dots were manually graded in a 1000 µm parafoveal area by number, diameter, location and perfusion status and traced through adjacent B-scans at 11 µm intervals to determine their length. Thereby, this study defined a procedure to identify granular and elongated hyperreflective elements and differentiate between presumably perfused and occluded capillaries. The latter were only found in the diabetic patients. This classification can potentially be automated to non-invasively identify capillary non-perfusion in vivo.

Preclinical ocular changes in systemic lupus erythematosus patients by optical coherence tomography.

The aim of the present study was to detect preclinical changes in SLE patients in retinal microvascularization or retinal and optical nerve structure by optical coherence tomography. This cross-sectional, single-centre study aimed to describe structural changes [macular and retinal nerve fibre layer (RNFL) thickness] by structural spectral-domain optical coherence tomography (SD-OCT) and perifoveal vascular [vessel density (VD) and vascular perfusion (VP) and foveal avascular zone (FAZ) structural parameters] findings by OCT angiography (OCTA) in 78 SLE patients and 80 healthy volunteers. In addition, we analysed their association with clinical and laboratory parameters, medications received, disease duration, and SLE activity and damage. Structural parameters by SD-OCT and perifoveal vascular parameters by OCTA were decreased in SLE patients compared with controls. OCTA parameters (VD, VP and FAZ circularity) and macular thickness were also decreased in patients with longer disease duration (>10 years). The presence of aPLs was associated with a decreased RNFL thickness, mainly in the inferior quadrants. Patients developing APS also showed decreased RNFL thickness and OCTA flow changes. SD-OCT and OCTA results were not associated with disease activity. Foveal structural parameters were lower in patients with higher damage score. SD-OCT and OCTA can detect preclinical structural and microcirculatory changes in SLE patients. Structural and perifoveal vascular macular changes in SLE patients are related to disease duration. Macular structural parameters were impaired in patients with higher disease damage. APS seems to be associated with preclinical damage to the optic nerve and impairment of the perifoveal microvasculature.

Volume-based, layer-independent, disease-agnostic detection of abnormal retinal reflectivity, nonperfusion, and neovascularization using structural and angiographic OCT.

Optical coherence tomography (OCT) is widely used in ophthalmic practice because it can visualize retinal structure and vasculature in vivo and 3-dimensionally (3D). Even though OCT procedures yield data volumes, clinicians typically interpret the 3D images using two-dimensional (2D) data subsets, such as cross-sectional scans or en face projections. Since a single OCT volume can contain hundreds of cross-sections (each of which must be processed with retinal layer segmentation to produce en face images), a thorough manual analysis of the complete OCT volume can be prohibitively time-consuming. Furthermore, 2D reductions of the full OCT volume may obscure relationships between disease progression and the (volumetric) location of pathology within the retina and can be prone to mis-segmentation artifacts. In this work, we propose a novel framework that can detect several retinal pathologies in three dimensions using structural and angiographic OCT. Our framework operates by detecting deviations in reflectance, angiography, and simulated perfusion from a percent depth normalized standard retina created by merging and averaging scans from healthy subjects. We show that these deviations from the standard retina can highlight multiple key features, while the depth normalization obviates the need to segment several retinal layers. We also construct a composite pathology index that measures average deviation from the standard retina in several categories (hypo- and hyper-reflectance, nonperfusion, presence of choroidal neovascularization, and thickness change) and show that this index correlates with DR severity. Requiring minimal retinal layer segmentation and being fully automated, this 3D framework has a strong potential to be integrated into commercial OCT systems and to benefit ophthalmology research and clinical care.

Alterations of optic tract and retinal structure in patients after thalamic stroke.

ObjectivesTo investigate the association between degeneration of retinal structure and shrinkage of the optic tract in patients after thalamic stroke.Materials and methodsPatients with unilateral thalamic stroke were included. Structural magnetic resonance imaging (MRI) and optical coherence tomography (OCT) were performed to obtain parameters of optic tract shrinkage (lateral index) and retina structural thickness (retinal nerve fiber layer, RNFL; peripapillary retinal nerve fiber layer, pRNFL; ganglion cell-inner plexiform layer, GCIP), respectively. Visual acuity (VA) examination under illumination was conducted using Snellen charts and then converted to the logarithm of the minimum angle of resolution (LogMAR). We investigated the association between LI and OCT parameters and their relationships with VA.ResultsA total of 33 patients and 23 age-sex matched stroke-free healthy controls were enrolled. Patients with thalamic stroke showed altered LI compared with control participants (P = 0.011) and a significantly increased value of LI in the subgroup of disease duration more than 6 months (P = 0.004). In these patients, LI were significantly associated with pRNFL thickness (β = 0.349, 95% confidence interval [CI]: 0.134–0.564, P = 0.002) after adjusting for confounders (age, sex, hypertension, diabetes, dyslipidemia, and lesion volume). LI and pRNFL were both significantly associated with VA in all patients (LI: β = −0.275, 95% CI: −0.539 to −0.011, P = 0.041; pRNFL: β = −0.023, 95% CI: −0.046 to −0.001, P = 0.040) and in subgroup of disease duration more than 6 months (LI: β = −0.290, 95% CI: −0.469 to −0.111, P = 0.002; pRNFL: β = −0.041, 95% CI: −0.065 to −0.017, P = 0.003).ConclusionShrinkage of the optic tract can be detected in patients with thalamic stroke, especially after 6 months of stroke onset. In these patients, the extent of optic tract atrophy is associated with pRNFL thickness, and they are both related to visual acuity changes.

Quantitative assessment of retinal vessel density and thickness changes in internal carotid artery stenosis patients using optical coherence tomography angiography

ObjectiveTo quantitatively assess the retinal features of patients with different degrees of internal carotid artery stenosis (ICAS), particularly mild ICAS patients, utilizing optical coherence tomography angiography (OCTA). MethodsThirty-two mild ICAS patients (mild ICAS group), 34 moderate to severe ICAS patients (nonmild ICAS group), and 40 controls were enrolled in this study. Retinal vessel density was quantitatively measured by OCTA, including radial peripapillary capillary vessel density (RPC-VD), superficial and deep capillary plexus vessel density (SCP/DCP-VD). Structural parameters were collected from optical coherence tomography (OCT), including retinal thickness and subfoveal choroidal thickness (SFCT). Furthermore, LASSO-penalized logistic regression was used to construct the diagnostic model based on retinal parameters. ROC curves and nomogram plots were used to assess the diagnostic ability of this model for ICAS. ResultsThe macular SCP-VD of mild ICAS patients was significantly lower than that of controls and lower than that of nonmild ICAS patients (all p < 0.05). However, there was no difference among the three groups in terms of DCP-VD (p > 0.05). RPC-VD could effectively discriminate between the mild ICAS group and the nonmild ICAS group (p = 0.005). For structural OCT, only the SFCT decreased as the ICAS degree increased (p < 0.05). Diagnostic scores based on retinal parameters showed a strong diagnostic capability for mild ICAS (AUC = 0.8656). ConclusionMild ICAS patients exhibited distinct retinal features compared to nonmild ICAS patients and control subjects. OCTA potentially represents a promising method for the early detection of ICAS patients and the noninvasive surveillance of haemodynamic changes in those patients.

INNER AND OUTER CHOROIDAL CHANGES IN THE FELLOW EYE OF PATIENTS WITH UNILATERAL CENTRAL SEROUS CHORIORETINOPATHY.

To quantitatively evaluate the inner and outer choroidal changes in the fellow eyes of patients with unilateral central serous chorioretinopathy (CSC). We analyzed data from patients with a diagnosis of unilateral CSC who had structural optical coherence tomography (OCT) and swept-source OCT angiography obtained. An additional group of age-matched healthy patients was included for comparison. The main outcome measures were: (1) choriocapillaris flow deficits' quantitative metrics; (2) choroidal luminal (LCA) and stromal (SCA) areas; and (3) choroidal vascularity index. Fellow unaffected eyes from 60 patients with unilateral CSC and 30 healthy subjects were included in the analysis. Mean ± SD age was 47.5 ± 9.9 years in the unilateral CSC group and 50.7 ± 10.8 years in the control group (P = 0.410). In the structural OCT assessment, both the LCA and SCA were increased in the unilateral CSC group (0.33 ± 0.11 and 0.29 ± 0.10 mm2) compared with healthy controls (0.28 ± 0.08 and 0.27 ± 0.05 mm2), although only differences in LCA reached a statistical significance (P = 0.041 and P = 0.286 for LCA and SCA, respectively). The choroidal vascularity index was higher in CSC patients (53.7 ± 3.6 and 50.9 ± 5.5%, P = 0.045). In the OCT angiography evaluation, the choriocapillaris flow deficits' percentage and number were increased in those patients affected by unilateral CSC. In multiple regressions, the strongest association with choriocapillaris percentage of flow deficits was with the presence of pachychoroid pigment epitheliopathy signs in the study eye (P < 0.0001). Our results corroborate the hypothesis that inner and outer choroidal changes affect both eyes of patients with unilateral disease.

Morphological and functional involvement of the inner retina in retinitis pigmentosa.

To investigate the morphological retinal parameters associated with retinal sensitivity status in retinitis pigmentosa (RP) through a quantitative multimodal imaging approach. The study was designed as an observational, prospective case series, including RP patients and healthy controls. Multimodal imaging included fundus autofluorescence (FAF), structural optical coherence tomography (OCT), OCT angiography (OCTA) and microperimetry (MP). The follow-up lasted 12 months. For each imaging modality, we performed an overall quantitative analysis and a detailed investigation based on the ETDRS-9 sectors grid. Quantitative parameters included the thickness of each retinal and choroidal layer, vessel density (VD), choriocapillaris porosity (CCP), FAF intensity and MP retinal sensitivity. We included 40 eyes (40 patients) affected by RP and 40 healthy eyes (40 controls). Mean baseline BCVA was 0.14 ± 0.18 LogMAR, with 0.18 ± 0.24 LogMAR after 1-year of follow-up. RP eyes showed statistically significant alterations of retinal and choroidal layers on the ETDRS-9 sectors grid, significant reduction of VD values and MP retinal sensitivity, and significantly higher CCP than controls. The inner retinal layers proved closely associated with the functional integrity of the posterior pole. In addition, our ROC analysis provided quantitative cutoffs connected significantly with a high probability of observing a partial sparing of MP retinal sensitivity. The inner retinal layers are closely associated with the functional integrity of the posterior pole in RP. FAF intensity reduction may be interpreted as lipofuscin metabolism impairment inducing increased phototoxic distress for retinal structures. Vascular involvement contributes to the morpho-functional deterioration of the macular region in RP.