Swept-source Optical Coherence Tomography Research Articles

Comment on: Evaluation of retinal and choroidal thickness changes in overweight and obese adults without ocular symptoms by swept-source optical coherence tomography

Comment on: Evaluation of retinal and choroidal thickness changes in overweight and obese adults without ocular symptoms by swept-source optical coherence tomography

Comparative study between swept-source and spectral-domain OCTA for imaging of choroidal neovascularization in age-related macular degeneration

AIM: To compare the differences of choroidal neovascularization (CNV) measurements between swept-source and spectral-domain optical coherence tomography angiography (SS-OCTA and SD-OCTA) in neovascular age-related macular degeneration (nAMD) and the imaging reliability of the two devices. METHODS: Prospective comparative study. SS-OCTA and SD-OCTA were used to scan the same eye with the modes of 3×3 and 6×6 mm2 centered on the neovascularization. Only qualified images were chosen and the border of CNV was manually delineated by two graders independently. The area of CNV (ACNV), vascular perfusion density (PD), and vessel length density (VLD) within the delineation were calculated using Image J. The differences of CNV measurements between the two OCTA devices were compared using Bland-Altman analysis. The agreement between the two graders on the measurements of each device was compared using the intraclass correlation coefficient (ICC). RESULTS: A total of 18 patients (22 eyes) with nAMD were included. The measurements of ACNV, PD, and VLD were 7.247±4.586 and 4.901±3.741 mm2, 43.202±9.636 and 34.904±10.489, 6.339±1.228 and 5.908±1.741 mm-1 for SS-OCTA and SD-OCTA, respectively. The differences between the two devices were 2.346±3.030 mm2 (Z= -3.782, P<0.0001), 8.298±14.160 (Z=-2.419, P=0.016), and 0.431±2.114 mm-1 (Z=-0.828, P=0.408) for ACNV, PD and VLD, respectively. The ICC between two graders were 0.893 (P<0.001), 0.902 (P<0.001), 0.885 (P<0.001) for ACNV, PD, VLD in SS-OCTA, and 0.971 (P<0.001), 0.976 (P<0.001), 0.973 (P<0.001) in SD-OCTA, respectively. CONCLUSION: Both OCTA devices have high imaging reliability. Compared with SD-OCTA, SS-OCTA has a larger ACNV measurements, but doesn't show better resolution of internal vessels of CNV and well signal strength.

Clinical and imaging characteristics associated with foveal neovascularization in proliferative diabetic retinopathy.

To assess the prevalence of foveal neovascularization (FNV) and its associated clinical features in proliferative diabetic retinopathy (PDR) eyes. Cross-sectional observational study. Participants underwent ultra-widefield photography, optical coherence tomography (OCT), and swept-source OCT angiography (SS-OCTA). FNV was defined as a hyperreflective lesion breaching the internal limiting membrane and displaying flow signal on OCTA, within 1-mm of foveal avascular zone. Vascular metrics were obtained from the ARI Network portal. Ischemic index (ISI) and inner choroid flow deficit percentage were calculated using FIJI from 12 × 12 and 6 × 6-mm scans, respectively. Logistic regression models were used to compare eyes with and without FNV. We included 249 eyes of 164 patients (age: 58 [50-65] years). FNV was identified in 20 eyes (8%). Univariate logistic regression revealed significant associations between FNV and younger age (p = 0.03), higher maximal HbA1c (p = 0.04), worse visual acuity (VA) (p = 0.01), presence of disorganization of retinal inner layers (DRIL) (p = 0.01), no macular posterior vitreous detachment (PVD) (p = 0.03), neovascularization elsewhere (NVE) and at the disc (NVD) (p = 0.01 and p = 0.001), and greater ISI (p = 0.04). In multivariable analysis, a significant association remained between FNV and worse VA (p = 0.04), NVD (p < 0.001), DRIL (p < 0.001), and absence of macular PVD (p = 0.01). No associations were found with SS-OCTA vascular metrics. This study provides a comprehensive characterization of FNV in PDR. FNV was identified in 8% of our cohort, being more prevalent in younger patients with severe PDR, as evidenced by NVD and DRIL presence. The absence of macular PVD may explain its association with younger age. What is known • Neovascularization at the fovea occurs rarely in proliferative diabetic retinopathy. • OCT and OCT-angiography can be used to evaluate foveal neovascularization, which may be associated with choroidal vascular abnormalities. What is new • Foveal neovascularization was seen in 8% of eyes with proliferative diabetic retinopathy in this cohort. • Risk factors for foveal neovascularization included younger age, absence of macular posterior vitreous detachment, presence of neovascularization of the disc, and presence of disorganization of retinal inner layers. • We did not identify an association between foveal neovascularization and choroidal perfusion abnormalities in this study.

Differentiation Between Pellucid-Like Keratoconus and Pellucid Marginal Degeneration Using Swept-Source Optical Coherence Tomography

Purpose: The distinction between pellucid-like keratoconus (PLK) and pellucid marginal corneal degeneration (PMD) based on tomographic examinations is difficult. In this study, corneal tomographic and biomechanical parameters, after classifying PMD and PLK using swept-source optical coherence tomography, were analyzed. Methods: Diagnoses of PLK and PMD were made using SS-OCT imaging, two groups were formed: PLK (n = 30) and PMD (n = 10). Corneal thickness was measured at the 5, 6, and 7 o'clock positions centrally, superiorly, and inferiorly with SS-OCT. Tomographic, densitometric, and biomechanical parameters were investigated using Scheimpflug-based methods. Results: Patients with PMD were significantly older than patients with PLK (55.2 [95% CI, 47.0–63.3] vs. 42.0 years [95% CI, 38.2–46.0]; P = 0.002). The median Kmax value did not differ significantly between PMD and PLK (54.7 D [95% CI, 48.0–62.8] vs. 52.0 D [95% CI, 49.4–53.9]; P = 0.5). Astigmatism was significantly higher in the PMD group than in the PLK group (median 9.0 D [6.1–11.5] D vs. 3.7 [2.4–4.6] D; P &lt; 0.001). The biomechanical parameters did not differ between PMD and PLK (DA Ratio max 2 mm, integrated radius, stiffness parameter at first applanation, and Corvis Biomechanical Index (CBI); each P &gt; 0.05). There were significant differences in the corneal thickness ratio inferior to the center between the two groups (−23.7% [−31.5 to (−15.9)] versus 2.4% [−1.2 to 5.9], P &lt; 0.001) and at 6 o'clock (−29% [−38.7 to −19.29] versus 0.18% [−4.62 to 5, P &lt; 0.001) and 7 o'clock (−24.5% [−34.2 to −14.7] versus −2.0% [−6.65 to 2.73], P &lt; 0.001). Conclusions: Neither Scheimpflug-based tomographic nor biomechanical parameters can differentiate between PLK and PMD. SS-OCT can help with this differentiation because of the typical thinning of corneal pachymetry near the limbus.

Choroidal Thickness and Visual Acuity in High Myopia Without Myopic Maculopathy: Insights From a Chinese Population Study.

To evaluate the association of choroidal thickness (ChT) with best-corrected visual acuity (BCVA) in patients with high myopia (HM) and without myopic maculopathy. This study was a retrospective, cross-sectional study of participants aged 7 to 70years with bilateral HM but without myopic maculopathy. Swept-source optical coherence tomography was used to measure ChT at the fovea. A BCVA of logMAR 0.1 was regarded as the benchmark for normal. The association between ChT and BCVA was evaluated by linear regression models with confounders fully adjusted. Subgroup analyses were performed across sex and age groups. A total of 412 eligible participants were enrolled in this study. The mean age, spherical equivalence, and subfoveal (SF) ChT of the included participants were 21.17 ± 9.55years, -9.77 ± 2.40 diopters, and 171.56 ± 61.33µm, respectively. The SF ChT was thinner in participants with abnormal BCVA (normal. 176.74 ± 60.24 µm; abnormal, 139.30 ± 58.63µm). A thinner ChT in all subregions of the posterior pole of the Early Treatment Diabetic Retinopathy Study grid was associated significantly with a worse BCVA after adjusting for age, sex, and axial length (SF ChT: coefficient, × 10-4, -2.64; 95% confidence interval, -4.73 to -0.55; P < 0.05 in all subregions). The strongest correlation was observed in the outer inferior region, where a per 21µm thinning of ChT led to a 0.01 worsening of BCVA. This correlation presented a stronger magnitude in male aged more than 40years. In patients with HM without myopic maculopathy, a thinner ChT was associated independently with a worse BCVA. The findings of this study suggest that thinning ChT should be considered a vital risk factor for irreparable visual acuity impairment.

Association of hypertension defined by the 2017 ACC/AHA guideline and choroidal thickness changes in type 2 diabetes: a 2-year longitudinal study.

This prospective cohort study investigated the longitudinal relationship between hypertension (HTN), defined by the 2017 ACC/AHA guidelines, and changes in choroidal thickness (CT) in patients with type 2 diabetes. Patients aged 30-80 years from the Guangzhou Diabetic Eye Study were categorized into non-HTN, stage 1-HTN, and stage 2-HTN groups based on BP criteria. Macular and parapapillary CT were measured using swept-source optical coherence tomography (SS-OCT). Mixed linear regression models analysed CT decline rates over a median 2.1-year follow-up, adjusting for confounders. 803 diabetes patients were included. Both stage 1-HTN and stage 2-HTN groups showed significantly thinner macular and parapapillary CT compared to non-HTN (all P < 0.05). Stage 2-HTN correlated with reduced macular CT thinning (coef = -11.29 μm/year; 95% CI, -22.36 to -0.22; P = 0.046) after adjustment, but not in the parapapillary area (coef = -4.07 μm/year; 95% CI, -12.89 to 4.74; P = 0.365). Subgroup analyses indicated faster macular CT decline in stage 2-HTN among those <65 years old (coef = -20.31 μm/year; 95% CI, -35.67 to -4.95; P = 0.10), males (coef = -14.1 μm/year; 95% CI, -32.54 to -4.33; P = 0.004), BMI ≥ 25 kg/m2 (coef = -10.24 μm/year; 95% CI, -26.86 to -6.38; P = 0.007), HbA1c > 6.5% (coef = -8.91 μm/year; 95% CI, -13.49 to -4.68; P = 0.001), and diabetes duration <10 years (coef = -12.78 μm/year; 95% CI, -27.48 to -1.91; P = 0.008). Stage 2-HTN is associated with accelerated macular CT loss in diabetic patients, suggesting macular CT measurements could potentially serve as early indicators of systemic hypertension. Further research is needed to establish precise CT cutoff values for clinical use in detecting and monitoring hypertension-related ocular changes.

Artificial intelligence-based prediction of neurocardiovascular risk score from retinal swept-source optical coherence tomography–angiography

The recent rise of artificial intelligence represents a revolutionary way of improving current medical practices, including cardiovascular (CV) assessment scores. Retinal vascular alterations may reflect systemic processes such as the presence of CV risk factors. The value of swept-source retinal optical coherence tomography–angiography (SS OCT-A) imaging is significantly enhanced by image analysis tools that provide rapid and accurate quantification of vascular features. We report on the interest of using machine-learning (ML) and deep-learning (DL) models for CV assessment from SS OCT-A microvasculature imaging. We assessed the accuracy of ML and DL algorithms in predicting the CHA2DS2-VASc neurocardiovascular score based on SS OCT-A retinal images of patients from the open-source RASTA dataset. The ML and DL models were trained on data from 491 patients. The ML models tested here achieved good performance with area under the curve (AUC) values ranging from 0.71 to 0.96. According to a classification into two neurocardiovascular risk groups, the EfficientNetV2-B3, a well suited DL model for retinal OCT-A images, predicted risk correctly in 68% of cases, with a mean absolute error (MAE) of approximately 0.697. Our models enable a confident prediction of the CHA2DS2-VASc score from SS OCT-A imaging, which could be a useful tool contributing to the assessment of neurocardiovascular profiles in the future.

112° field of view high-resolution swept-source OCT angiography for rat retinas.

This study introduces an ultra-wide field (UWF) and high-resolution swept-source optical coherence tomographic angiography (OCTA) system for rat retinal imaging. Using an asymmetrical optics design, the system achieves unprecedented details of retinal structures and vascular plexuses over a large field of view (112°) in a single-shot acquisition. Views of single-nerve fiber bundles and single capillary vessels are consistently visible over a 112° field of view. The system has a long imaging range and high penetration and allows a full view of vitreous hyaloid vessels, retina, choroid, sclera, and posterior ciliary arteries, down to sub-sclera connective tissues. In a longitudinal study of oxygen-induced retinopathy (OIR) in rats, the system successfully revealed the progression and regression of OIR-related vascular pathologies, such as ischemia, neovascularization, and tortuosity. To our knowledge, this novel UWF-OCT/OCTA prototype designed for rat retinal imaging will be a vital tool for monitoring disease progression and evaluating therapeutic interventions in preclinical models.

Accurate attenuation characterization in optical coherence tomography using multi-reference phantoms and deep learning

The optical attenuation coefficient (AC), a crucial tissue parameter indicating the rate of light attenuation within a medium, enables quantitative analysis of tissue properties and facilitates tissue differentiation. Despite its growing clinical significance, accurate quantification of AC from optical coherence tomography (OCT) signals remains a pressing concern. This study comprehensively investigates the factors influencing the accuracy of quantitative AC extraction among existing OCT-based AC extraction algorithms. Subsequently, we propose an approach, the Multi-Reference Phantom Driven Network (MR-Net), which leverages multi-reference phantoms and deep learning to implicitly model factors affecting OCT signal propagation, thereby automatically regressing AC. Using a dataset from Intralipid and silicone-TiO2 phantoms with known AC values obtained from a collimated transmission system and imaged with a 1300 nm swept-source OCT system, we conducted a thorough comparison focusing on data length, out-of-focus distance, and reference phantoms’ attenuation among existing OCT-based AC extraction algorithms. By leveraging this extensive dataset, MR-Net can automatically model the complex physical effects in the transmission process of OCT signals, significantly enhancing the accuracy of AC predictions. MR-Net outperforms other algorithms in all metrics, achieving an average relative error of only 10.43% for calculating attenuation samples, significantly lower than the lowest value of 23.72% achieved by other algorithms. This method offers a quantitative framework for disease diagnosis, ultimately contributing to more accurate and effective tissue characterization in clinical settings.

A small disc size, a big challenge: effect of optic disc size on the correlation between peripapillary choroidal thickness, peripapillary retinal nerve fiber layer, and ganglion cell layer.

We aimed to analyze the effect of optic disc size on the correlation between the peripapillary choroid (PPC), peripapillary retinal nerve fiber layer (RNFL), and macular ganglion cell inner plexiform layer (MGCIPL) thicknesses in subjects with ocular hypertension (OHT) and primary open angle glaucoma (POAG). This study included 61 eyes with a disc area (DA) of ≤ 1.63 mm2, 92 eyes with a DA of 1.63-2.42 mm2, and 59 eyes with a DA of ≥ 2.42 mm2 in small disc, regular disc, and large disc groups, respectively. The swept-source optical coherence tomography scans of the PPC, RNFL, and MGCIPL were analyzed according to disc size. The three groups did not significantly differ in RNFL or MGCIPL measurements, but the PPC measurement was statistically significantly higher in the small disc group and statistically significantly thinner in the large disc group. Most of the correlations observed between the RNFL and MGCIPL measurements and eye characteristics in the regular disc group were not detected in the small and large disc groups. While the RNFL and MGCIPL were well correlated in all disc size groups, the PPC did not correlate with the RNFL or MGCIPL in any of the groups. Overall, the RNFL and MGCIPL measurements were consistent across all three disc sizes. While the PPC was thicker in small discs than in larger discs, it was not correlated with the RNFL or MGCIPL.

Early Choriocapillaris Dysfunction in Fellow Eyes of Patients with Unilateral Neovascular Age-Related Macular Degeneration.

To investigate early changes in AMD by evaluating and comparing choriocapillaris (CC) flow in fellow eyes of patients with unilateral neovascular age-related macular degeneration (nAMD) and in healthy controls using swept-source optical coherence tomography angiography (SS-OCTA). Patients with unilateral nAMD and no/early/intermediate AMD (no/e/iAMD) in their fellow eye and normal controls who underwent SS-OCT and OCTA where included. CC perfusion was assessed on MATLAB as percentage of flow deficits (FD%) in the central 4.5 × 4.5 mm macular region, after removing artifacts. 81 eyes/patients (22 eyes with noAMD, 30 with eAMD, 29 with iAMD) with unilateral nAMD and 24 controls were analyzed. Median FD% was 8.97 (IQR 8.58-9.53) in AMD group, 8.92 (IQR 8.64-9.27) in noAMD group, 8.96 (IQR 8.46-9.38) in eAMD group, 9.05 (IQR 8.58-9.8) in iAMD group, and 8.22 (IQR 7.78-8.55) in controls. A statistically significant difference in FD% was observed between controls and AMD group (p < 0.001), as well as between each AMD subgroup and controls (noAMD vs controls p = 0.0037; eAMD vs control p = 0.0012; iAMD vs controls p = 0.0002). This study suggests that CC dysfunction may occur in fellow eyes of patients with unilateral nAMD before visible AMD signs, potentially preceding RPE changes. Further longitudinal studies are needed to confirm these findings and explore the correlation with AMD development/progression.

Choroidal thickness in macular, nasal midperiphery, and temporal midperiphery regions and its relationship with axial length and refractive error.

This study aimed to investigate the choroidal thickness (ChT) distribution in adult myopic eyes, focusing on the macular, nasal midperiphery, and temporal midperiphery regions, and to explore its relationship with axial length (AL) and refractive error. A cross-sectional, observational study. Twenty-nine eyes of 29 adult volunteers were examined. ChT was measured using high-speed swept-source optical coherence tomography covering an area of 50 degrees in three different regions: centered at macular, nasal side at 33 degrees, and temporal side at 33 degrees. Statistical analyses were performed to assess differences in ChT between regions and correlations with AL and spherical equivalent (SE). ChT was found to be thickest in the macular region, followed by the nasal and temporal midperiphery regions. Significant correlations were observed between AL/SE and ChT in the macular and temporal regions, but not in the nasal region. The temporal midperiphery showed the strongest correlation with AL and SE. This study revealed a nasal-temporal asymmetry in ChT distribution in myopic eyes, with the temporal midperiphery showing the thinnest ChT. The strong correlations between ChT in the temporal midperiphery and AL/SE suggest a role for the temporal choroid in axial elongation and myopia progression. These findings highlight the importance of considering peripheral ChT in understanding ocular growth and myopia management.

Morphometrics of polypoidal choroidal vasculopathy lesions and choroidal vascular associated with treatment response using swept-source optical coherence tomography angiography

PurposeTo evaluate quantitative metrics of neovascularization lesions and choroidal vascular using swept-source optical coherence tomography angiography (SS-OCTA) in polypoidal choroidal vasculopathy (PCV) eyes, and investigate the relationship between imaging biomarkers and treatment outcomes of intravitreal anti-vascular endothelial growth factor (VEGF). MethodsWe retrospectively recruited 56 PCV patients. Choroidal features included subfoveal choroidal thickness (SFCT) and choroidal vascularity index (CVI). Quantitative metrics of neovascularization lesions included total vessel length (TVL), average vessel length (AVL), junction density (JD), total number of endpoints (TNE), and mean lacunarity (ML). We performed multivariate logistic and linear regression models to determine the prognostic factors for functional and morphological outcomes. ResultsBy comparison, functional good-responders had poorer best corrected visual acuity, higher TNE, and lower ML at baseline. Morphological good-responders had higher central retinal thickness, higher TNE, lower TVL and AVL, lower ML, lower SFCT and CVI. High-shrinkage of vessel area subgroup had higher JD and TNE, lower TVL and AVL, lower ML, lower SFCT and CVI. Multivariate analysis showed good morphological response was correlated with lower SFCT (P < 0.01). High-shrinkage subgroup was correlated with lower AVL (P = 0.017) and higher TNE (P < 0.01). ConclusionQuantitative metrics of neovascularization lesions and choroidal characteristics using SS-OCTA had the potential to be imaging biomarkers for predicting the response to anti-VEGF treatment. PCV lesions with higher TNE and lower AVL tended to appear higher shrinkage of vessel area, and lower SFCT was correlated with good morphological response.

Decreased choriocapillaris vessel density in the ipsilateral eye after carotid artery revascularization detected by widefield SS-OCTA.

ObjectiveTo investigate the short-term blood flow changes and image features of the retina and choroid in patients undergo carotid artery revascularization (CAR) for severe carotid artery stenosis (SCAS) using widefield swept-source optical coherence tomography angiography (SS-OCTA). DesignProspective study. ParticipantsThis prospective study included 112 eyes (56 eyes of the ipsilateral side and 56 eyes of the contralateral side) of 56 participants with severe carotid artery stenosis. MethodsParticipants were examined using widefield SS-OCTA covering an area of 16*16mm centered on the fovea before and after carotid artery revascularization. Retinal parameters including central macular thickness (CMT), vessel density of the retinal superficial vascular complex (VDRSVC), vessel density of the retinal deep vascular complex (VDRDVC), and vessel density of the retina (VDR) and choroidal parameters including central choroidal thickness (CCT), vessel density of the choriocapillaris (VDCC), vessel density of the medium and large choroidal vessels (VDMLC), choroidal vessel volume ratio (CVV/a), and three-dimensional choroidal vascularity index (3D-CVI) were measured. Besides, preoperative and postoperative OCTA images were screened and compared. Main Outcome MeasuresRetinal and choroidal parameters obtained from SS-OCTA. ResultsIn the ipsilateral eye (56 eyes), increase of VDRSVC, VDR, CVV/a, CCT, and 3D-CVI and decrease of VDCC was found after CAR. 13 patients were identified with postoperative ipsilateral choriocapillaris flow voids (PICCFVs) with OCTA images, and presence of PICCFVs was associated with greater postoperative VDCC decrease. In the contralateral eye (56 eyes), we found increase of VDRSVC, VDRDVC, VDR, while no difference of choroidal parameters after CAR and no findings of PICCFVs. ConclusionsFindings of this study suggest that ocular microvascular perfusion is improved after CAR in the ipsilateral eye and the contralateral eye within a wide field of the fundus. The VDCC is decreased in the ipsilateral eye, which may indicate infarctions of choriocapillaris or ischemia-reperfusion injury of the choriocapillaris after CAR.

In vivo lacrimal gland imaging artefact assessment based on swept-source optical coherence tomography for dry eye disease.

This study aimed to characterise imaging artefacts in the lacrimal gland using swept-source optical coherence tomography (SS-OCT) in patients with dry eye disease (DED) and healthy participants and identify risk factors for these artefacts. In total, 151 eyes, including 104 from patients with DED and 47 from non-DED participants, were analysed. Demographic data collection, comprehensive ocular examinations and SS-OCT imaging of the palpebral lobe of the lacrimal gland were performed. Artefacts were classified into distinct categories with different severities. Univariate and multivariate logistic regression analyses were performed to evaluate the association of age, gender, best-corrected visual acuity, intraocular pressure (IOP) and the presence of DED with the presence of artefacts. Eight artefact types and severity grading were defined by analysing 1208 lacrimal SS-OCT images. The three most prevalent artefacts were defocus (75.83%), cliff (67.47%) and Z-off (58.44%). The presence of artefacts was significantly associated with the presence of DED (OR=9.13; 95% CI, 2.39 to 34.88; p=0.001) and higher IOP (OR=1.34; 95% CI, 1.14 to 1.58; p<0.001). Furthermore, multivariate logistic analyses showed that lower tear film breakup time (OR=0.71; 95% CI, 0.55 to 0.92; p=0.009) and higher meibum quality score (OR=2.86; 95% CI, 1.49 to 5.48; p=0.002) were significantly associated with higher odds for the presence of artefacts. DED eyes had more SS-OCT image artefacts than normal eyes. Stringent standardised image quality control should be implemented before further image analysis when using SS-OCT to assess lacrimal gland image.

Long-Term Impact of Carotid Endarterectomy on Choroidal and Choriocapillaris Perfusion: The INFLATE Study

PurposeWhen performed for clinically significant carotid artery stenosis (CAS), the long-term impact of carotid endarterectomy (CEA) on choroidal and choriocapillaris (CC) circulation was studied using swept-source optical coherence tomography angiography (SS-OCTA). DesignProspective observational study. ParticipantsPatients with clinically significant CAS undergoing unilateral CEA. MethodsSS-OCTA scans were performed on both eyes at baseline (before CEA), within one week post-CEA (short-term follow-up [FU]), and at least 30 days post-CEA (long-term FU). Using validated algorithms, we measured mean choroidal thickness (MCT), choroidal vascularity index (CVI), choroidal vessel volume (CVV), CC flow deficit percentage (CC FD%), and CC thickness within the 5mm circle centered on the fovea for both the eye ipsilateral to CEA (surgical side) and the contralateral eye (nonsurgical side). Multivariable regression analysis was conducted to evaluate the impact of baseline demographic and clinical factors on the changes in choroidal and CC parameters. Main Outcome MeasuresBoth the short- and long-term changes in MCT, CVI, CVV, CC FD%, and CC thickness. ResultsThe study included 58 eyes from 29 patients. Significant short-term improvements in MCT (P<0.001) and CC thickness (P=0.006) were observed post-CEA on the surgical side. Long-term FU showed sustained increases in MCT compared with baseline (P=0.02), while CC thickness was not significantly different from baseline (P=0.10). The CVI did not change significantly from baseline at either short-term (P=0.45) or long-term (P=0.22) FU on the surgical side. While CVV demonstrated a short-term rise immediately post-CEA (P<0.001), the difference was not statistically significant at the long-term evaluation (P=0.06). No significant improvement in CC FD% from baseline was observed at any visit post-CEA (short-term P=0.81, long-term P=0.91). The nonsurgical side only showed a significant reduction in CVI at the long-term FU visit compared with before CEA (P=0.01). Clinical variables such as age, degree of stenosis, diabetes, hypertension, and smoking status did not greatly impact the outcomes. ConclusionsUnilateral CEA demonstrated a sustained increase in MCT suggesting persistent improvements in choroidal perfusion in the ipsilateral eye.

Discriminant prediction equation using an optical biometer for identifying postmyopic laser vision correction eyes.

To create an equation for identifying postmyopic laser vision correction (M-LVC) eyes by using corneal shape parameters in a swept-source optical coherence tomography (SS-OCT) biometer and verify its accuracy. Nagoya Eye Clinic, Nagoya, Japan. Retrospective evaluation of a screening approach. Control participants were selected retrospectively from patients who visited the clinic for cataract surgery or refractive surgery. M-LVC patients were selected retrospectively from patients who visited the clinic for cataract surgery or M-LVC postoperative checkups. The control and post-M-LVC patients with keratometric values between 39 diopters (D) and 43 D were included in the final analysis. Patients were randomly assigned to equation-creation and validation groups in a 2:1 ratio. To discriminate post-M-LVC patients from control participants, multiple logistic regression analysis was performed with the corneal shape parameters from the optical biometer as independent variables. The M-LVC and control groups consisted of 90 eyes from 90 patients and 97 eyes from 97 patients, respectively. The average keratometry (Ave-K) values did not differ significantly between the control and M-LVC groups ( P = .187). The multiple logistic analysis identified the asymmetry component (regression coefficient, 5.357; odds ratio, 212.158) and corneal eccentricity index (regression coefficient, -5.088; odds ratio, 0.006) as explanatory variables. The area under the receiver operating characteristic curve in the predictive equation-creation group was 0.946. The sensitivity and specificity in the validation group were 93.3% and 87.5%, respectively. The M-LVC discriminant prediction equation with the topography-equipped SS-OCT biometer was effective in detecting post-M-LVC eyes with high accuracy.

Association of Peripapillary Arterial Circle of Zinn-Haller with Glaucoma in Highly Myopic Eyes.

The visualization of circle of Zinn-Haller (CZH) on optical coherence tomography angiography (OCTA) or its pattern does not have a clear effect on glaucoma, while the location of CZH is associated with axial length in highly myopic eyes. To investigate the association between the CZH and the presence of glaucoma using swept-source optical coherence tomography angiography (SS-OCTA) images of the optic nerve of patients with high myopia (HM). This retrospective case series included 227 eyes with HM, comprising 134 and 93 eyes with and without glaucoma, respectively. The characteristics of CZH, including visualization, pattern, and location, were assessed using SS-OCTA. Vascular parameters, such as vessel density and microvascular dropout (MvD), were quantified. The factors affecting the presence of glaucoma and the correlations between the CZH distance and axial length (AXL) were identified using logistic regression analysis and Pearson correlation analysis, respectively. CZH was detected more frequently in HM patients with glaucoma (71.6%) than in patients without glaucoma (51.6%) (P<0.002). However, the visualization of CZH was not related to the presence of glaucoma in multivariate regression analysis (odds ratio [OR], 0.688; 95% confidence interval [CI], 0.328-1.444; P=0.322). Moreover, compared to the annular pattern used as a reference, triangular and irregular patterns were not associated with the presence of glaucoma (OR: 1.043, 95% CI: 0.101-10.763, P=0.971; OR: 0.527, 95% CI: 0.255-1.092, P=0.085, respectively). MvD was significantly higher in patients with glaucoma (61.2%) than that in patients without glaucoma (2.2%) (P<0.001) and was identified as a significant factor affecting the presence of glaucoma (OR, 42.120; 95% CI, 9.416-188.413; P<0.001). AXL showed a significant correlation with CZH distance in all patients (R=0.399; P<0.001). CZH was more commonly detected in HM patients with glaucoma. However, no clear associations of glaucoma with the visualization, pattern, or location of CZH were observed in the present study. The correlation between AXL and CZH distance in eyes with HM warrants further investigation. These results may offer insights into the pathogenesis of glaucoma in eyes with HM as OCTA technology advances.

Comparison of Precision, Agreement, and Accuracy of Two Swept-Source Optical Coherence Tomography Biometers.

Background/Objectives: This study's aim was to compare the precision, agreement, and accuracy in axial length (AL) measurements of Argos® (Alcon Healthcare, US) and Eyestar 900® (Haag-Streit, Switzerland) swept-source optical coherence tomography (SS-OCT) biometers. Methods: We performed a prospective evaluation of two diagnostic devices. Three consecutive measurements of AL with the Argos® and the Eyestar® 900 SS-OCT biometers were conducted in random order in eyes undergoing cataract surgery in Barcelona, Spain. The main endpoint was the median difference in AL between devices. Secondary endpoints included agreement on Bland-Altman plots and 95% limits of agreement (LoAs), repeatability as measured within-subject standard deviation (SW), percent of failed AL measurements, percent of eyes within ±0.50 D and ±1.00 D one month after surgery, and median and mean prediction error. Results: We included 107 eyes of 107 patients (60.8% females, mean age of 73.1 years). The median difference in AL (Argos®-Eyestar 900®) was -0.01 mm (interquartile range [IQR], 0.06), p = 0.01. The 95% LoAs were -0.11 to +0.08 mm, with a trend towards less extreme measurements with Argos® for very short and long eyes. The median (IQR) Sw was 0.0058 (0.0058) and 0.0000 (0.0058) for Argos® and Eyestar 900®, respectively. There were no failed AL measurements with either device (0%, 95% CI = 0% to 3.4%). Overall, 96.1% of eyes were within ±0.50 D and 100% were within ±1.00 D. Conclusions: Argos® and Eyestar 900® provided statistically different but clinically negligible differences in AL. However, they are not interchangeable in very long or short eyes, due to the different principles used to determine AL.

Widefield optical coherence tomography by electro-optical modulation

Optical coherence tomography (OCT) is a unique imaging modality capable of axial sectioning with a resolution of only a few microns. Its ability to image with high resolution deep within tissue makes it ideal for material inspection, dentistry, and, in particular, ophthalmology. Widefield retinal imaging has garnered increasing clinical interest for the detection of numerous retinal diseases. However, real-time applications in clinical practice demand the contrast of swept-source OCT at scan speeds that limit their depth range. The curvature of typical samples, such as teeth, corneas, or retinas, thus restricts the field-of-view of fast OCT systems. Novel high-speed swept sources are expected to further improve the scan rate; however, not without exacerbating the already severe trade-off in depth range. Here, we show how, without the need for mechanical repositioning, harmonic images can be rapidly synthesized at any depth. This is achieved by opto-electronic modulation of a single-frequency swept source laser in tandem with tailored numerical dispersion compensation. We demonstrate experimentally how real-time imaging of highly-curved samples is enabled by extending the effective depth-range 8-fold. Even at the scan speed of a 400 kHz swept source, harmonic OCT enables widefield retinal imaging.