In Vivo Imaging of Rodent Retina in Retinal Disease.

High-quality imaging of the retina is crucial to the diagnosis and monitoring of disease, as well as for evaluating the success of therapeutics in human patients and in preclinical animal models. Here, we describe the basic principles and methods for in vivo retinal imaging in rodents, including fundus imaging, fluorescein angiography, optical coherence tomography, fundus autofluorescence, and infrared imaging. After providing a concise overview of each method and detailing the retinal diseases and conditions that can be visualized through them, we will proceed to discuss the advantages and disadvantages of each approach. These protocols will facilitate the acquisition of optimal images for subsequent quantification and analysis. Additionally, a brief explanation will be given regarding the potential results and the clinical significance of the detected abnormalities.

High accuracy patient-specific 3D coronary reconstruction from angiography and intravascular optical coherence tomography.

The integration of digital subtraction angiography (DSA) with intravascular optical coherence tomography (IVOCT) offers a comprehensive 3D arterial model, which is invaluable for the analysis of vascular anatomy and biomechanics. However, the process of image fusion is often hindered by the challenge of accurately orienting IVOCT images. This paper introduces a novel, to our knowledge, dual-path 3D reconstruction method that leverages the guidewire and the vessel's centerline to establish cross sectional direction vectors within the IVOCT images and spatial direction vectors along the guidewire's trajectory. This approach minimizes the accumulation of reconstruction errors by ensuring the precise orientation of each vascular cross section. The efficacy of the proposed method is validated through vascular phantom experiments and the reconstruction of patient-specific 3D coronary models.

A new texture-based labeling framework for hyper-reflective foci identification in retinal optical coherence tomography images.

An important abnormality in Optical Coherence Tomography (OCT) images is Hyper-Reflective Foci (HRF). This anomaly can be interpreted as a biomarker of serious retinal diseases such as Age-related Macular Degeneration (AMD) and Diabetic Macular Edema (DME) or the progression of disease from an early stage to a late one. In this paper, a new method is proposed for the identification of HRFs. The new method divides the OCT B-scan into patches and separately verifies each patch to determine whether or not the patch contains an HRF. The procedure of patch verification contains a texture-based framework which assigns appropriate labels according to intensity changes to each column and row. Then, a feature vector is extracted for each patch based on the assigned labels. The feature vectors are utilized in the training step of well-known classifiers like Support Vector Machine (SVM). Then, the classifiers are used to produce the labels for the test OCT images. The new method is evaluated on a public dataset including HRF labels. The experimental results show that the new method is capable of providing outstanding results in terms of speed and accuracy.

Predictive value of optical coherence tomography angiography in management of diabetic macular edema.

BACKGROUND: Optical coherence tomography angiography (OCTA) is a relatively new extension of Optical coherence tomography (OCT) that generates non-invasive, depth-resolved images of the retinal microvasculature which allows for the detection of various features of diabetic retinopathy. OBJECTIVES: This study aimed to detect biomarkers that may predict an early anatomical response to the treatment of diabetic macular edema (DME) with intravitreal ranibizumab (IVR) by means of OCTA. PATIENTS AND METHODS: This prospective interventional study was undertaken on 111 eyes of 102 naïve participants who had diabetic macular edema; enrolled patients were evaluated by taking a complete ophthalmologic history, examination and investigations by use of a pre-designed checklist involving Optical Coherence Tomography Angiography. RESULTS: Regarding the best corrected visual acuity (BCVA) the Mean ± SD was 0.704 ± 0.158 preoperatively and 0.305 ± 0.131 postoperatively in good responder patients; and was 0.661 ± 0.164 preoperatively and 0.54 ± 0.178 postoperatively in poor responders. The central macular thickness (CMT) was 436.22 ± 54.66 µm preoperatively and 308.12 ± 33.09 µm postoperatively in good responder patients; and was 387.74 ± 44.05 µm preoperatively and 372.09 ± 52.86 µm postoperatively in poor responders. By comparing the pre injection size of the foveal avascular zone area (FAZ-A) in both groups, it found that the mean ± SD of FAZ-A was 0.297 ± 0.038 mm in good responder patients compared to 0.407 ± 0.05 mm in non-responder patients. The preoperative superficial capillary plexus (SCP) foveal vascular density (VD) was 24.02 ± 3.01% in good responder patients versus 17.89 ± 3.19% um in poor responders. The preoperative SCP parafoveal VD was 43.06 ± 2.67% in good responder patients versus 37.96 ± 1.82% um in poor responders. The preoperative deep capillary plexus (DCP) foveal VD was 30.58 ± 2.89% in good responder patients versus 25.45 ± 3.14% in poor responders. The preoperative DCP parafoveal VD was 45.66 ± 2.21% in good responder patients versus 43.26 ± 2.35% um in poor responders, this was statistically significant. CONCLUSION: OCTA offers an accurate measurement for VD in the macula as well as the FAZ-A which could be used to predict an early anatomical response of anti-VEGF treatment in DME.

Longitudinal Assessment of Retinal Microvasculature in Preclinical Alzheimer's Disease.

Purpose: To investigate if changes in vessel density (VD) and the foveal avascular zone (FAZ) occur in the preclinical phase of Alzheimer's disease (pAD) over time. Methods: Optical coherence tomography angiography (OCTA) was used to image VD and FAZ at baseline and for a follow-up period of 2 years. Positron emission tomography (PET) was used to determine the amyloid beta (Aß) status of participants. Results: The VD and FAZ of 148 participants (54% female) were analyzed at baseline and follow-up (mean time between measurements, 2.24 ± 0.35 years). The mean age of the participants was 68.3 ± 6.0 years at baseline and 70.3 ± 5.9 years at follow-up. Participants were divided into three groups: control group, participants who had negative Aß status at both measurements (Aß-, n = 116); converter group, participants who transitioned from negative to positive between baseline and follow-up (Aß-+, n = 18); and participants who were consistently positive at both visits (Aß++, n = 14). The VD of both Aß+ groups demonstrated non-significant increases over time in both macula and optic nerve head (ONH) regions. The Aß- group was found to be significantly higher in both ONH and macular regions. The VD of the Aß++ group was significantly higher in the macula inner and outer rings compared to the Aß-+ and Aß- groups. No significant change was found in FAZ values over time. Conclusions: Alterations in VD seem to manifest already in pAD, exhibiting distinct variations between the ONH and macula. Further longitudinal studies with a longer follow-up design and known amyloid pathology should be undertaken to validate these observations.

Normative Profile of Retinal Nerve Fiber Layer Thickness and Lamina Cribrosa-Related Parameters in a Healthy Non-Glaucoma Cynomolgus Monkey Colony.

Purpose: The purpose of this study was to investigate the normal range of ophthalmic parameters and the correlations between systematic and ocular parameters and retinal nerve fiber layer (RNFL) thickness among a healthy non-glaucoma cynomolgus monkey colony. Methods: All included monkeys were given detailed ophthalmic examinations, including anterior and posterior segments. Furthermore, univariate and multivariate linear regression models were conducted to estimate the relationship between systemic and ophthalmic parameters and global RNFL thickness. Results: A total of 349 non-glaucoma monkeys (18.69 ± 2.88 years old) were collected. The global RNFL thickness was 94.61 ± 10.13 µm, and sex-specific differences existed in all sectors. The decreasing trend of RNFL is as follows: inferotemporal, superotemporal, inferonasal, superonasal, temporal, and nasal. For lamina cribrosa (LC)-related parameters, cup depth (P < 0.01), LC thickness (P = 0.014), and Bruch's membrane opening (BMO) - minimum rim width 2 (P = 0.002) were greater in the male group. However, LC depth (P = 0.02), anterior laminar insertion depth-1 (P = 0.009), and mean anterior laminar insertion depth (P = 0.029) of female monkeys were greater than those of male monkeys. In multivariate linear regression, only older age was significantly related to reduced global RNFL thickness (P < 0.001). Conclusions: Our findings suggest the differences in RNFL thickness distribution and sex between non-glaucoma cynomolgus monkeys and humans. Therefore, the impact of this difference on outcomes should be fully considered in laboratory animal studies. Our findings are also significant in terms of developing a normative optical coherence tomography (OCT) database in nonhuman primates (NHPs). Translational Relevance: We found that the differences in RNFL thickness distribution and sex between non-glaucoma cynomolgus monkey colonies and humans should be thoroughly taken into account in laboratory animal studies.

Characteristics of a Large Database of Healthy Eyes From Optometry Practices: Implications for a Real-World Reference Database.

Purpose: To compare an optical coherence tomography (OCT) real-world reference database (RW-RDB) of "healthy" eyes obtained from optometry practices to a commercial reference database (RDB). Methods: OCT scans from 6804 individuals 18 years and older were sampled from a larger database tested at 10 optometry practices involved in refractive and screening services. Employing a reading center method, OCT scans from both eyes of 4932 (4.9K) individuals were judged to be of acceptable quality with an absence of pathology. The 4.9K RW-RDB was compared to a commercial RDB with 398 eyes (398 RDB). Results: The means and distributions of global circumpapillary retinal nerve fiber layer (G-cpRNFL) and global ganglion cell layer (G-GCL) thickness, as well as five key anatomical parameters affecting cpRNFL thickness, were not significantly different for all but one parameter (fovea-to-disc distance) and one thickness metric (G-cpRNFL). In both cases, the difference amounted to less than 1.5%. By design, the number of 4.9K RW-RDB eyes 70 years and older (724, 14.7%) was greater than for the 398 RDB (40, 10.1%). The error bands on the 5% and 1% quantile regression lines (QRLs) were substantially narrower for the 4.9K RW-RDB. Conclusions: The 398 RDB and 4.9K RW-RDB have similar characteristics and appear to come from a similar population. However, the large size of the 4.9K RW-RDB leads to narrower error bands of the QRLs, which has the potential to increase accuracy. Translational Relevance: The larger RW-RDB offers the opportunity to better characterize healthy eyes for clinical diagnosis and clinical trials by furthering our understanding of the patterns of artifacts, exploring covariates, developing separate RW-RDBs, and/or improving AI models.

Optical Coherence Tomography Split-Spectrum Amplitude-Decorrelation Optoretinography Detects Early Central Cone Photoreceptor Dysfunction in Retinal Dystrophies.

Purpose: To investigate if split-spectrum amplitude-decorrelation optoretinography (SSADOR) can detect and measure macular cone dysfunction in inherited retinal dystrophies (IRDs). Methods: This study was a case series of participants presenting with various IRD pathologies. Participants were recruited from the Ophthalmic Genetics clinic at the Casey Eye Institute from February to August 2023. Multimodal and SSADOR imaging was obtained in all cases. Results: We recruited nine participants, including four with macular dystrophy, one with fundus flavimaculatus, one with cone dystrophy, and three with retinitis pigmentosa. SSADOR decorrelation maps identified areas of cone functional impairment consistent with disease phenotypes. A correlation between the SSADOR signal and retinal sensitivity measured by microperimetry within the central 20° diameter area was observed. Additionally, SSADOR was able to demonstrate a decreased signal in mild cases when microperimetry measurements were still normal but subtle changes were also apparent on structural OCT. Conclusions: SSADOR is sensitive at detecting functional changes in macular cones, even prior to abnormalities in perimetry testing. We highlight the potential benefits of this innovative technology for the early detection of cone dysfunction and their potential contributions to earlier diagnosis and more accurate monitoring of progression. Translational Relevance: SSADOR is an innovative technology that detects early macular cone function changes, allowing for early diagnosis and precise monitoring of cone dysfunction progression. By serving as a potential clinical trial endpoint, SSADOR facilitates the translation of scientific findings into practical applications, ultimately improving patient care and outcomes.

Artificial Intelligence-Assisted Perfusion Density as Biomarker for Screening Diabetic Nephropathy.

Purpose: To identify a reliable biomarker for screening diabetic nephropathy (DN) using artificial intelligence (AI)-assisted ultra-widefield swept-source optical coherence tomography angiography (UWF SS-OCTA). Methods: This study analyzed data from 169 patients (287 eyes) with type 2 diabetes mellitus (T2DM), resulting in 15,211 individual data points. These data points included basic demographic information, clinical data, and retinal and choroidal data obtained through UWF SS-OCTA for each eye. Statistical analysis, 10-fold cross-validation, and the random forest approach were employed for data processing. Results: The degree of retinal microvascular damage in the diabetic retinopathy (DR) with the DN group was significantly greater than in the DR without DN group, as measured by SS-OCTA parameters. There were strong associations between perfusion density (PD) and DN diagnosis in both the T2DM population (r = -0.562 to -0.481, P < 0.001) and the DR population (r = -0.397 to -0.357, P < 0.001). The random forest model showed an average classification accuracy of 85.8442% for identifying DN patients based on perfusion density in the T2DM population and 82.5739% in the DR population. Conclusions: Quantitative analysis of microvasculature reveals a correlation between DR and DN. UWF PD may serve as a significant and noninvasive biomarker for evaluating DN in patients through deep learning. AI-assisted SS-OCTA could be a rapid and reliable tool for screening DN. Translational Relevance: We aim to study the pathological processes of DR and DN and determine the correspondence between their clinical and pathological manifestations to further clarify the potential of screening DN using AI-assisted UWF PD.

Artificial Intelligence-Enhanced OCT Biomarkers Analysis in Macula-off Rhegmatogenous Retinal Detachment Patients.

Purpose: To identify optical coherence tomography (OCT) biomarkers for macula-off rhegmatogenous retinal detachment (RRD) with artificial intelligence (AI) and to correlate these biomarkers with functional outcomes. Methods: Patients with macula-off RRD treated with single vitrectomy and gas tamponade were included. OCT volumes, taken at 4 to 6 weeks and 1 year postoperative, were uploaded on an AI-derived platform (Discovery OCT Biomarker Detector; RetinAI AG, Bern, Switzerland), measuring different retinal layer thicknesses, including outer nuclear layer (ONL), photoreceptor and retinal pigmented epithelium (PR + RPE), intraretinal fluid (IRF), subretinal fluid, and biomarker probability detection, including hyperreflective foci (HF). A random forest model assessed the predictive factors for final best-corrected visual acuity (BCVA). Results: Fifty-nine patients (42 male, 17 female) were enrolled. Baseline BCVA was 0.5 logarithmic minimum angle of resolution (logMAR) ± 0.1, significantly improving to 0.3 ± 0.1 logMAR at the final visit (P < 0.001). Average thickness analysis indicated a significant increase after the last follow-up visit for ONL (from 95.16 ± 5.47 µm to 100.8 ± 5.27 µm, P = 0.0007) and PR + RPE thicknesses (60.9 ± 2.6 µm to 66.2 ± 1.8 µm, P = 0.0001). Average occurrence rate of HF was 0.12 ± 0.06 at initial visit and 0.08 ± 0.05 at last follow-up visit (P = 0.0093). Random forest model revealed baseline BCVA as the most critical predictor for final BCVA, followed by ONL thickness, HF, and IRF presence at the initial visit. Conclusions: Increased ONL and PR-RPE thickness associate with better outcomes, while HF presence indicates poorer results, with initial BCVA remaining a primary visual predictor. Translational Relevance: The study underscores the role of novel biomarkers like HF in understanding visual function in macula-off RRD.

Two-year outcomes of intravitreal conbercept therapy for polypoidal choroidal vasculopathy.

BACKGROUND: This study aims to evaluate the two-year outcomes of polypoidal choroidal vasculopathy (PCV) treated with conbercept and to investigate the predictive response factors. METHODS: Consecutive patients with PCV who received three-loading intravitreal conbercept, followed by as-needed reinjections, were studied retrospectively. The best corrected visual acuity (BCVA), central retinal thickness (CRT) and polyps were evaluated. Patients who achieved dry maculae in month 6 were categorised into the dry group, or otherwise, into the non-dry group. The predictive factors for a dry macula were evaluated. RESULTS: A total of 25 eyes from 25 patients (17 males; mean age: 62.8 ± 6.4 years) were included. At month 24, the average BCVA increased significantly from 49.9 ± 15.0 letters to 57.2 ± 16.0 letters (p = 0.040); the average CRT decreased significantly from 430.16 ± 166.55 µm to 278.31 ± 157.34 µm (p = 0.00), and 88% of the eyes achieved dry maculae. The number of polyps changed from 55 to 20 (fading rate: 63.6%; p < 0.001). The mean number of intravitreal injections was 8.6 ± 5.4. The dry group (10 eyes, 40%) was more likely to have higher branching vascular network vessel density (BVN VD; p = 0.021), submacular haemorrhages (p = 0.011) but lack polyp-related serous pigmented epithelial detachment (PED) (p = 0.037). CONCLUSIONS: Conbercept was effective in eyes with PCV at maintaining functional and anatomical improvement. Baseline characteristics, including BVN VD, the presence of polyps with serous PED and submacular haemorrhage, seemed to be related to the response to conbercept.

Role of fundus autofluorescence imaging in the management of submacular hemorrhage.

PURPOSE: To evaluate the baseline characteristics of fundus autofluorescence (FAF) in patients with submacular hemorrhage (SMH). METHODS: This retrospective study included patients diagnosed with treatment-naive, foveal-involving subretinal hemorrhage (size > 2-disc diameters) of any etiology, presenting between June 2017 and June 2023. Only cases with good-quality color fundus photographs, optical coherence tomography (OCT) scans, and blue-light FAF images at baseline were included. SMH imaging characteristics were documented and correlated with treatment outcomes. A successful treatment outcome was defined as the reduction, displacement or clearance of the SMH from beneath the fovea. RESULTS: Nineteen cases of SMH (13 males, 6 females), ranging from 14 to 85 years, were analyzed. Neovascular age-related macular degeneration (nAMD) was the most common etiology (n = 11, 58%). Baseline visual acuity ranged from 6/9 to counting fingers at ½ meter, with a median presentation time of 7 days from symptom onset (range: 1-57 days). Treatment success was observed in 13 eyes (68%). Hypoautofluoroscence on FAF was significantly associated with SMH resolution (p = 0.021). However, no association was found between treatment success and clinical hemorrhage characteristics (p = 0.222), OCT findings (p = 0.222), or specific treatments (p > 0.05). Hypoautofluoroscence on FAF was the sole predictor of treatment success, as demonstrated by Spearman's correlation (r = 0.637; p = 0.003) and linear regression analysis (p = 0.003). CONCLUSION: FAF, in conjunction with color fundus photography and OCT, may provide valuable insights for clinicians in formulating treatment strategies for patients with SMH. Hypoautofluoroscence on FAF was a significant predictor of successful SMH resolution in this study.

Is there a relationship between the keratoconus and the peripapillary choroidal vasculature?

PURPOSE: To evaluate the peripapillary/parapapillary choroidal vascular parameters in the keratoconus (KC) and to determine the relationship between topography parameters and the peripapillary/parapapillary choroidal vascular parameters. METHOD: Ninety eyes of ninety patients with different stages of KC and 29 eyes of twenty-nine patients without KC were enrolled in the study. Patients with KC were divided into three groups according to the Amsler-Krumeich classification scale. The choroidal vasculature was assessed by choroidal vascular parameters [such as parapapillary choroidal microvascular density (pCMVd) and peripapillary choroidal vascularity index (pCVI)]. These parameters were also evaluated for correlation with other parameters. RESULT: The retinal nerve fibre layer thickness (RNFLT) of the superior-temporal area and the pCVI were decreased in group 3 compared to the control group (superiror-temporal RNFLT: 122.27 ± 21.43 vs 139.90 ± 21.7, p = 0.01 and pCVI: 67.04 ± 4.14 vs 69.99 ± 4.38, p = 0.04). The superior-temporal RNFLT was decreased in group 3 compared to group 2 (122.27 ± 21.43 vs 141.83 ± 25.58, p = 0.006). There was a negative correlation between pCVI and average simulated keratometry (mean sim K), but this association was weak (r = - 0.29 p = 0.001). CONCLUSION: This study demonstrated that there may be changes in pCVI in patients with grade 3 KC and that there may be an association between pCVI and mean sim K. As KC grade increases, pCVI may decrease. Furthermore, pCVI may have a negative correlation with mean sim K.

Critical Impact of Working Distance on OCT Imaging: Correction of Optical Distortion and Its Effects on Measuring Retinal Curvature.

Purpose: To assess the impact of working distance (WD) on optical distortion in optical coherence tomography (OCT) imaging and to evaluate the effectiveness of optical distortion correction in achieving consistent retinal Bruch's membrane (BM) layer curvature, regardless of variations in WD. Methods: Ten subjects underwent OCT imaging with four serial macular volume scans, each employing distinct WD settings adjusted by balancing the sample and reference arm of the OCT interferometer (eye length settings changed). Either of two types of 30° standard objectives (SOs) was used. A ray tracing model was used to correct optical distortion, and BM layer curvature (represented as the second derivative of the curve) was measured. Linear mixed effects (LME) modeling was used to analyze factors associated with BM layer curvature, both before and after distortion correction. Results: WD exhibited significant associations with axial length (ß = -1.35, P < 0.001), SO type (P < 0.001), and eye length settings (P < 0.001). After optical distortion correction, the mean ± SD BM layer curvature significantly increased from 16.80 ± 10.08 µm-1 to 49.31 ± 7.50 µm-1 (P < 0.001). The LME model showed a significant positive association between BM layer curvature and WD (ß = 1.94, P < 0.001). After distortion correction, the percentage change in BM layer curvature due to a 1-mm WD alteration decreased from 9.75% to 0.25%. Conclusions: Correcting optical distortion in OCT imaging significantly mitigates the influence of WD on BM layer curvature, enabling a more accurate analysis of posterior eye morphology, especially when variations in WD are unavoidable.

Acute effects of swimming goggle wearing on intraocular pressure, anterior chamber biometrics, and optic nerve head morphology.

Swimming goggles (SG) are widely used in water sports, and this study aimed to evaluate the acute effects of wearing SG on intraocular pressure (IOP), anterior chamber biometrics, axial length (AL), and optic nerve head (ONH) morphology. Twenty-eight healthy young adults participated in this cross-sectional study, with assessed parameters including IOP, central corneal thickness (CCT), anterior chamber depth (ACD), anterior chamber angle (ACA), AL, and optical coherence tomography (OCT) imaging of the ONH, specifically Bruch membrane opening (BMO), Bruch membrane opening-minimum rim width (BMO-MRW), lamina cribrosa depth (LCD), and prelaminar tissue (PLT). Measurements were taken at four time points: before wearing SG, at the 1st and 10th minutes of wearing, and immediately after removal. The results showed a significant increase in IOP at the 1st and 10th minutes of SG wear compared to pre-wear and post-removal values. Additionally, decreases in CCT, ACD, and ACA, along with an increase in AL, were observed while wearing SG. However, these changes reverted to baseline after the goggles were removed. No significant alterations were detected in ONH parameters during the study. The findings suggest that wearing SG induces an acute rise in IOP and changes in anterior segment parameters, likely due to oculopression, but does not appear to affect ONH morphology in the short term. Further studies are needed to investigate any potential long-term effects.

Influence of OCT biomarkers on microperimetry intra- and interdevice repeatability in diabetic macular edema.

To evaluate the intra- and interdevice repeatability of microperimetry (MP) assessments in patients with diabetic macular edema (DME) two consecutive MP testings (45 fovea-centered stimuli, 4-2 staircase strategy) were performed using MP3 (NIDEK, Aichi, Japan) and MAIA (CenterVue, Padova, Italy), respectively. Intraretinal fluid (IRF) and ellipsoid zone (EZ) thickness were automatically segmented by published deep learning algorithms. Hard exudates (HEs) were annotated semi-automatically and disorganization of retinal inner layers (DRIL) was segmented manually. Point-to-point registration of MP stimuli to corresponding spectral-domain OCT (Spectralis, Heidelberg Engineering, Germany) locations was performed for both devices. Repeatability was assessed overall and in areas of disease-specific OCT biomarkers using Bland-Altmann coefficients of repeatability (CoR). A total of 3600 microperimetry stimuli were tested in 20 eyes with DME. Global CoR was high using both devices (MP3: ± 6.55 dB, MAIA: ± 7.69 dB). Higher retest variances were observed in stimuli with IRF (MP3: CoR ± 7.4 dB vs. ± 6.0 dB, p = 0.001, MAIA: CoR ± 9.2dB vs. ± 6.8 dB, p = 0.002) and DRIL on MP3 (CoR ± 6.9 dB vs. ± 3.2 dB, p < 0.001) compared to stimuli without. Repeatabilities were reduced in areas with thinner EZ layers (both p < 0.05). Fixation (Fuji classification) was relatively unstable independent of device and run. These findings emphasize taking higher caution using MP in patients with DME.

Optical coherence tomography to guide percutaneous coronary intervention.

Percutaneous coronary intervention (PCI) has been most commonly guided by coronary angiography. However, to overcome the inherent limitations of conventional coronary angiography, there has been an increasing interest in the adjunctive tools of intracoronary imaging for PCI guidance. Recently, optical coherence tomography (OCT) has garnered substantial attention as a valid intravascular imaging modality for guiding PCI. However, despite the unparalleled high-resolution imaging capability of OCT, which offers detailed anatomical information on coronary lesion morphology and PCI optimisation, its broad application in routine PCI practice remains limited. Several factors may have curtailed the widespread adoption of OCT-guided PCI in daily practice, including the transitional challenge from intravascular ultrasound (IVUS), the experienced skill required for image acquisition and interpretation, the lack of a uniform algorithm for OCT-guided PCI optimisation, and the limited clinical evidence. Herein, we provide an in-depth review of OCT-guided PCI, involving the technical aspects, optimal strategies for OCT-guided PCI, and the wide application of OCT-guided PCI in various anatomical subsets. Special attention is given to the latest clinical evidence from recent randomised clinical trials with respect to OCT-guided PCI.

Repeatability and agreement of two swept-source optical coherence tomographers and scheimpflug imaging for measurements of corneal curvature.

PURPOSE: To evaluate the repeatability and agreement of two swept-source optical coherence tomographers and Scheimpflug imaging for corneal curvature in healthy subjects to obtain data on the clinical application of a new device. METHODS: This prospective study was conducted in January and February 2021 with 100 healthy subjects at the Eye Hospital of Wenzhou Medical University. Simulated keratometry (Sim-K), posterior keratometry (Kp), total corneal power (TCP), and total corneal astigmatism (TCA) were measured with CASIA2, Anterion, and Pentacam. Within-subject standard deviation (Sw), repeatability coefficient (RC), coefficient of variation (CoV), and intraclass correlation coefficient (ICC) were used to assess inter-device repeatability. Bland-Altman analysis was performed to determine inter-device agreement. RESULTS: The three devices showed good repeatability for Sim-K, Kp, and TCP with all ICC > 0.980. Pentacam showed the highest repeatability (ICC ≥ 0.993; ICC ≥ 0.993) while the CASIA2 demonstrated the lowest repeatability (ICC: ≥ 0.986; ICC: ≥ 0.985) for Sim-K and TCP. Anterion and CASIA2 revealed better repeatability (ICC ≥ 0.998; ICC ≥ 0.981) for Kp than Pentacam (ICC ≥ 0.980). Pentacam and Anterion showed good repeatability for TCA (ICC: 0.935 and 0.916), whereas the CASIA2 showed moderate repeatability (ICC: 0.836). Three instruments demonstrated good agreement with the maximum absolute 95% Limits of agreement (LoA) of 1.00 D for Sim-K, Kp, and TCP. Wide LoA were found for TCA with the maximum absolute 95% LoA ≥ 0.66 D between the three devices. CONCLUSIONS: In healthy subjects, the three devices (Pentacam, Anterion and CASIA2) displayed comparable repeatability and accuracy for SimK, Kp, and TCP, and could be used interchangeably for these parameters. However, TCA measured by the three devices was not interchangeable. TRIAL REGISTRATION: Chinese Clinical Trial Registry Center (10/10/2020, ChiCTR2000038959).

Initial Retinal Nerve Fiber Layer Loss and Risk of Diabetic Retinopathy Over a Four-Year Period.

Purpose: The purpose of this study was to investigate whether the rapid rate of peripapillary retinal nerve fiber layer (pRNFL) thinning in short-term is associated with the future risk of developing diabetic retinopathy (DR). Methods: This prospective cohort study utilized 4-year follow-up data from the Guangzhou Diabetic Eye Study. The pRNFL thickness was measured by optical coherence tomography (OCT). DR was graded by seven-field fundus photography after dilation of the pupil. Correlations between pRNFL thinning rate and DR were analyzed using logistic regression. The additive predictive value of the prediction model was assessed using the C-index, net reclassification index (NRI), and integrated discriminant improvement index (IDI). Results: A total of 1012 patients with diabetes (1012 eyes) without DR at both baseline and 1-year follow-up were included in this study. Over the 4-year follow-up, 132 eyes (13%) developed DR. After adjusting for confounding factors, a faster rate of initial pRNFL thinning was significantly associated with the risk of DR (odds ratio per standard deviation [SD] decrease = 1.15, 95% confidence interval [CI] = 1.08 to 1.23, P < 0.001). Incorporating either the baseline pRNFL thickness or its thinning rate into conventional prediction models significantly improved the discriminatory power. Adding the rate of pRNFL thinning further enhanced the discriminative power compared with models with only baseline pRNFL thickness (C-index increased from 0.685 to 0.731, P = 0.040). The IDI and NRI were 0.114 and 0.463, respectively (P < 0.001). Conclusions: The rate of initial pRNFL thinning was associated with DR occurrence and improved discriminatory power of traditional predictive models. This provides new insights into the management and screening of DR.

Ganglion Cell Complex Thickness and Visual Function in Chronic Leber Hereditary Optic Neuropathy.

Purpose: To evaluate the correlation between the macular ganglion cell complex (GCC) thickness measured with manually corrected segmentation and visual function in individuals with chronic Leber hereditary optic neuropathy (LHON). Methods: Twenty-six chronic LHON subjects (60% treated with idebenone or Q10) from the Swedish LHON registry were enrolled. Best-corrected visual acuity (BCVA), visual field tests, and optical coherence tomography (OCT) were performed. Visual field was evaluated with the Haag-Streit Octopus 900 with the Esterman test and a custom 30° test. Canon OCT-HS100 scans were exported to the Iowa Reference Algorithm. GCC thickness was obtained after the segmentation was corrected manually in nine macular sectors. Results: The GCC thickness was overestimated by 16 to 30 µm in different macular sectors with the automated segmentation compared with the corrected (P < 0.001). GCC thickness in all sectors showed significant correlation with all functional parameters. The strongest correlation was seen for the external temporal sector (BCVA: r = 0.604, P < 0.001; mean defect: r = 0.457, P = 0.001; Esterman score: r = 0.421, P = 0.003). No differences were seen between treated and untreated subjects with regard to GCC and visual field scores (P > 0.05), but BCVA was better among treated subjects (P = 0.017). Conclusions: The corrected GCC thickness showed correlation with visual function in chronic LHON subjects. The frequently occurring segmentation errors in OCT measurements related to chronic LHON can potentially be misleading in monitoring of disease progression and in evaluating the treatment effects. Precise measurements of GCC could serve as a sensitive tool to monitor structural changes in LHON. We therefore emphasize the importance of careful evaluation of the accuracy of OCT segmentation.