Cross-sectional Optical Coherence Tomography Research Articles

Defining the structure–function relationship of specific lesions in early and advanced age-related macular degeneration

The objective of this study is to define structure–function relationships of pathological lesions related to age-related macular degeneration (AMD) using microperimetry and multimodal retinal imaging. We conducted a cross-sectional study of 87 patients with AMD (30 eyes with early and intermediate AMD and 110 eyes with advanced AMD), compared to 33 normal controls (66 eyes) recruited from a single tertiary center. All participants had enface and cross-sectional optical coherence tomography (Heidelberg HRA-2), OCT angiography, color and infra-red (IR) fundus and microperimetry (MP) (Nidek MP-3) performed. Multimodal images were graded for specific AMD pathological lesions. A custom marking tool was used to demarcate lesion boundaries on corresponding enface IR images, and subsequently superimposed onto MP color fundus photographs with retinal sensitivity points (RSP). The resulting overlay was used to correlate pathological structural changes to zonal functional changes. Mean age of patients with early/intermediate AMD, advanced AMD and controls were 73(SD = 8.2), 70.8(SD = 8), and 65.4(SD = 7.7) years respectively. Mean retinal sensitivity (MRS) of both early/intermediate (23.1 dB; SD = 5.5) and advanced AMD (18.1 dB; SD = 7.8) eyes were significantly worse than controls (27.8 dB, SD = 4.3) (p < 0.01). Advanced AMD eyes had significantly more unstable fixation (70%; SD = 63.6), larger mean fixation area (3.9 mm2; SD = 3.0), and focal fixation point further away from the fovea (0.7 mm; SD = 0.8), than controls (29%; SD = 43.9; 2.6 mm2; SD = 1.9; 0.4 mm; SD = 0.3) (p ≤ 0.01). Notably, 22 fellow eyes of AMD eyes (25.7 dB; SD = 3.0), with no AMD lesions, still had lower MRS than controls (p = 0.04). For specific AMD-related lesions, end-stage changes such as fibrosis (5.5 dB, SD = 5.4 dB) and atrophy (6.2 dB, SD = 7.0 dB) had the lowest MRS; while drusen and pigment epithelial detachment (17.7 dB, SD = 8.0 dB) had the highest MRS. Peri-lesional areas (20.2 dB, SD = 7.6 dB) and surrounding structurally normal areas (22.2 dB, SD = 6.9 dB) of the retina with no AMD lesions still had lower MRS compared to controls (27.8 dB, SD = 4.3 dB) (p < 0.01). Our detailed topographic structure–function correlation identified specific AMD pathological changes associated with a poorer visual function. This can provide an added value to the assessment of visual function to optimize treatment outcomes to existing and potentially future novel therapies.

The role of ultra-widefield imaging with navigated central and peripheral cross-sectional and three-dimensional swept source optical coherence tomography in ophthalmology: Clinical applications.

To assess central and peripheral retinal and choroidal diseases using ultra-widefield (UWF) fundus imaging in combination with navigated central and peripheral cross-sectional and three-dimensional (3D) swept source optical coherence tomography (SS-OCT) scans. Retrospective study involving 332 consecutive patients, with a nearly equal distribution of males and females. The mean age of patients was 52 years (range 18-92 years). Average refractive error was -3.80 D (range +7.75 to -20.75 D). The observations in this study demonstrate the efficacy of peripheral navigated SS-OCT in assessing various ocular conditions. The technology provides high-quality images of the peripheral vitreous, vitreoretinal interface, retina, and choroid, enabling visualization of vitreous floaters and opacities, retinal holes and tears, pigmented lesions, and peripheral retinal degenerations. 3D OCT scans enhance the visualization of these abnormalities and improve diagnostic and therapeutic decisions. Navigated central and peripheral cross-sectional and 3D SS-OCT scans offer significant complementary benefits in the assessment and management of retinal diseases. Their addition to UWF imaging provides a comprehensive view of central and peripheral ocular structures, aiding in early detection, precise anatomical measurements, and objective monitoring of disease progression. In addition, this technology serves as a valuable tool for patient education, a teaching tool for trainees, and documentation for medico-legal purposes.

CENTRAL BOUQUET HEMORRHAGE: Clinical and Multimodal Imaging Features.

To describe the clinical characteristics, multimodal imaging features, and anatomic basis of a distinctive pattern of deep retinal hemorrhages located in the central fovea, a presentation referred to as "central bouquet hemorrhage." Retrospective, observational, multicenter case series of eyes with central bouquet hemorrhage. Multimodal imaging features were reviewed and analyzed. Ten eyes from 10 patients (4 women and 6 men), with a mean age of 55.6 ± 21.7 years (range 25-84 years) were included. Underlying etiologies were neovascular age-related macular degeneration (40%), lacquer cracks in pathological myopia (30%), macular telangiectasia Type 2 (10%), proliferative diabetic retinopathy (10%), and ocular trauma associated with angioid streaks (10%). On ophthalmoscopy, all eyes with central bouquet hemorrhage displayed a deep retinal hemorrhage with round margins in the central fovea and associated with petaloid hemorrhages radiating in the surrounding Henle fiber layer. Cross-sectional optical coherence tomography showed a well-delineated round hyperreflective lesion involving the central foveal Henle fiber layer/outer nuclear layer in all cases. Accompanying hyperreflective hemorrhages tracking along the obliquely oriented Henle fiber layer were present in all eyes. Resolution occurred in all patients, either spontaneously (30%) or after treatment with intravitreal anti-vascular endothelial growth factor injections (70%), and was associated with partial visual acuity improvement (from 20/113 to 20/36). "Central bouquet hemorrhage" is a novel descriptive term describing a characteristic round pattern of intraretinal blood in the fovea associated with Henle fiber layer hemorrhage and encountered in a spectrum of macular disease.

Pressure-Insensitive Epidermal Thickness of Fingertip Skin for Optical Image Encryption.

In this study, an internal fingerprint-guided epidermal thickness of fingertip skin is proposed for optical image encryption based on optical coherence tomography (OCT) combined with U-Net architecture of a convolutional neural network (CNN). The epidermal thickness of fingertip skin is calculated by the distance between the upper and lower boundaries of the epidermal layer in cross-sectional optical coherence tomography (OCT) images, which is segmented using CNN, and the internal fingerprint at the epidermis-dermis junction (DEJ) is extracted based on the maximum intensity projection (MIP) algorithm. The experimental results indicate that the internal fingerprint-guided epidermal thickness is insensitive to pressure due to normal correlation coefficients and the encryption process between epidermal thickness maps of fingertip skin under different pressures. In addition, the result of the numerical simulation demonstrates the feasibility and security of the encryption scheme by structural similarity index matrix (SSIM) analysis between the original image and the recovered image with the correct and error keys decryption, respectively. The robustness is analyzed based on the SSIM value in three aspects: different pressures, noise attacks, and data loss. Key randomness is valid by the gray histograms, and the average correlation coefficients of adjacent pixelated values in three directions and the average entropy were calculated. This study suggests that the epidermal thickness of fingertip skin could be seen as important biometric information for information encryption.

DIRECTIONAL OPTICAL COHERENCE TOMOGRAPHY IMAGING OF MACULAR PATHOLOGY.

To survey the impact of directional reflectivity on structures within optical coherence tomography images in retinal pathology. Sets of commercial optical coherence tomography images taken from multiple pupil positions were analyzed. These directional optical coherence tomography sets revealed directionally reflective structures within the retina. After ensuring sufficient image quality, resulting hybrid and composite images were characterized by assessing the Henle fiber layer, outer nuclear layer, ellipsoid zone, and interdigitation zone. Additionally, hybrid images were reviewed for novel directionally reflective pathological features. Cross-sectional directional optical coherence tomography image sets were obtained in 75 eyes of 58 patients having a broad range of retinal pathologies. All cases showed improved visualization of the outer nuclear layer/Henle fiber layer interface, and outer nuclear layer thinning was, therefore, more apparent in several cases. The ellipsoid zone and interdigitation zone also demonstrated attenuation where a geometric impact of underlying pathology affected their orientation. Misdirected photoreceptors were also noted as a consistent direction-dependent change in ellipsoid zone reflectivity between regions of normal and absent ellipsoid zone. Directional optical coherence tomography enhances the understanding of retinal anatomy and pathology. This optical contrast yields more accurate identification of retinal structures and possible imaging biomarkers for photoreceptor-related pathology.

Optical Coherence Tomography as a Non-Invasive Tool for Plant Material Characterization in Agriculture: A Review.

Characterizing plant material is crucial in terms of early disease detection, pest control, physiological assessments, and growth monitoring, which are essential parameters to increase production in agriculture and prevent unnecessary economic losses. The conventional methods employed to assess the aforementioned parameters have several limitations, such as invasive inspection, complexity, high time consumption, and costly features. In recent years, optical coherence tomography (OCT), which is an ultra-high resolution, non-invasive, and real-time unique image-based approach has been widely utilized as a significant and potential tool for assessing plant materials in numerous aspects. The obtained OCT cross-sections and volumetrics, as well as the amplitude signals of plant materials, have the capability to reveal vital information in both axial and lateral directions owing to the high resolution of the imaging system. This review discusses recent technological trends and advanced applications of OCT, which have been potentially adapted for numerous agricultural applications, such as non-invasive disease screening, optical signals-based growth speed detection, the structural analysis of plant materials, and microbiological discoveries. Therefore, this review offers a comprehensive exploration of recent advanced OCT technological approaches for agricultural applications, which provides insights into their potential to incorporate OCT technology into numerous industries.

Narrowing Ratio of Retinal Veins at Arteriovenous Crossing in Patients With Branch Retinal Vein Occlusion Versus That in Healthy Individuals.

This cross-sectional study aimed to clarify the differences in the retinal venous narrowing ratio (VNR) at retinal arteriovenous crossing by optical coherence tomography (OCT) among the eyes with branch retinal vein occlusion (BRVO), fellow eyes of patients with BRVO, and eyes of individuals without BRVO and to determine factors that influence the VNR. We studied 31 eyes of young participants, 54 eyes of an older control group, 56 fellow eyes of patients with BRVO, and 48 eyes with BRVO. Cross-sectional OCT images were used to determine the VNR at two arteriovenous crossings per eye. Overall, 378 arteriovenous crossings were analyzed. The VNR of arterial overcrossings of fellow eyes (27.7% ± 11.1%) and BRVO eyes (27.3% ± 9.76%) were significantly higher than those in the young (16.0% ± 7.9%, all P<0.001) and control (22.0% ± 8.81%, P<0.001, P=0.003, respectively) groups. The VNR of arterial overcrossings was significantly larger than that of venous overcrossings (24.0% ± 10.5% vs. 20.6% ± 13.0%, P=0.021). A linear mixed-effects model showed that the VNR was significantly higher in arterial overcrossings, crossings with larger arterial internal diameters, smaller venous internal diameters, and participants with older age and a BRVO history. The VNR in arterial overcrossings was higher in BRVO eyes and even in the fellow eyes. Thus, a higher VNR in arterial overcrossings may contribute to BRVO development, and crossings with factors contributing to higher VNR might be associated with a risk of BRVO.

Recovery course of persistent posterior subretinal fluid after successful repair of rhegmatogenous retinal detachment.

To investigate best corrected visual acuity (BCVA), subretinal fluid (SRF) absorption time or ellipsoid zone (EZ) restoration time and various variables in patients with persistent SRF after successful primary repair of rhegmatogenous retinal detachment (RRD). This retrospective multicenter study allowed independent analysis of the healing pattern by two observers based on composite of serial cross-sectional macular optical coherence tomography (OCT) scans. Univariate and multivariate analyses were implemented. One hundred and three cases had persistent SRF after pars plana vitrectomy, scleral buckling, or pneumatic retinopexy. By univariate analysis, SRF resolution time correlated positively with the number of retinal breaks (p < 0.001) and with increased myopia (p = 0.011). Using multivariate analysis, final BCVA (log MAR) correlated positively with age, duration of RRD, initial BCVA (OR = 3.28; [95%CI = 1.44-7.47]; p = 0.015), and SRF resolution time (OR = 0.46 [95%CI 0.21-1.05]; p = 0.049). EZ restoration time was longer with increasing number of retinal tears (OR = 0.67; [95%CI 0.29-1.52]; p = 0.030), worse final BCVA, and presence of macula-off RRD (OR = 0.26; [95%CI 0.08-0.88]; p = 0.056). SRF resolution time correlated marginally with prone position. Residual posterior SRF is more common in eyes with multiple breaks or in myopic eyes. Final BCVA is better in younger subjects and in eyes with shorter duration of RRD. Persistent SRF is a self-limited disorder with a mean resolution of 11.2 months with good visual prognosis improving from a mean baseline logMAR of 1.08 to 0.25 at one year.

In vivo characterisation of field pea stem wall thickness using optical coherence tomography

BackgroundModern field pea breeding faces a significant challenge in selecting lines with strong stems that resist lodging. Traditional methods of assessing stem strength involve destructive mechanical tests on mature stems after natural senescence, such as measuring stem flexion, stem buckling or the thickness of dry stems when compressed, but these measurements may not correspond to the strength of stems in the living plant. Optical coherence tomography (OCT) can be used as a noncontact and nondestructive method to measure stem wall thickness in living plants by acquiring two- or three-dimensional images of living plant tissue.ResultsIn this proof-of-principle study, we demonstrated in vivo characterisation of stem wall thickness using OCT, with the measurement corrected for the refractive index of the stem tissue. This in vivo characterisation was achieved through real-time imaging of stems, with an acquisition rate of 13 milliseconds per two-dimensional, cross-sectional OCT image. We also acquired OCT images of excised stems and compared the accuracy of in vivo OCT measurements of stem wall thickness with ex vivo results for 10 plants each of two field pea cultivars, Dunwa and Kaspa. In vivo OCT measurements of stem wall thickness have an average percent error of − 3.1% when compared with ex vivo measurements. Additionally, we performed in vivo measurements of both stem wall thickness and stem width at various internode positions on the two cultivars. The results revealed that Dunwa had a uniform stem wall thickness across different internode positions, while Kaspa had a significantly negative slope of − 0.0198 mm/node. Both cultivars exhibited an increase in stem width along the internode positions; however, Dunwa had a rate of increase of 0.1844 mm/node, which is three times higher than that of Kaspa.ConclusionsOur study has demonstrated the efficacy of OCT for accurate measurement of the stem wall thickness of live field pea. Moreover, OCT shows that the trends of stem wall thickness and stem width along the internode positions are different for the two cultivars, Dunwa and Kaspa, potentially hinting at differences in their stem strength. This rapid, in vivo imaging method provides a useful tool for characterising physical traits critical in breeding cultivars that are resistant to lodging.

Optical Coherence Tomography Based Differentiation of Intravitreal Particles in Posterior Uveitis and Vitreous Hemorrhage

Purpose: to study optical coherence tomography (OCT) characteristics of intravitreal particles in vitreous hemorrhage and posterior uveitis. Patients and methods. 29 patients with posterior uveitis (43.1 ± 19.4 years, 10 females and 19 males) and 29 patients with vitreous hemorrhage (62.3 ± 11.6 years, 9 females and 20 males) were included. All patients received standard ophthalmological examination and multimodal imaging, including OCT. The size and reflectivity of preretinal intravitreal particles was assessed on crosssectional OCT scans. Results: Intravitreal particles in eyes with posterior uveitis had a statistically significantly larger size compared to the particles in vitreous hemorrhage, 47.0 ± 29.0 and 41.3 ± 22.6 pixels, respectively (p &lt; 0.001). At the same time, intravitreal particles in eyes with posterior uveitis had lower mean reflectivity compared with eyes with vitreous hemorrhage, 126.0 ± 10.5 and 135.2 ± 11.1, respectively (p &lt; 0.001). The maximum reflectivity of intravitreal particles in eyes with posterior uveitis was also lower than that of particles in eyes with vitreous hemorrhage, 186.2 ± 24.9 and 166.3 ± 23.7, respectively (p &lt; 0.001). Conclusion. Intravitreal particles displayed with OCT in posterior uveitis are less reflective and larger than those in vitreous hemorrhage.

Discrimination of multiple sclerosis using OCT images from two different centers.

Multiple sclerosis (MS) is one of the most prevalent chronic inflammatory diseases caused by demyelination and axonal damage in the central nervous system. Structural retinal imaging via optical coherence tomography (OCT) shows promise as a noninvasive biomarker for monitoring of MS. There are successful reports regarding the application of Artificial Intelligence (AI) in the analysis of cross-sectional OCTs in ophthalmologic diseases. However, the alteration of thicknesses of various retinal layers in MS is noticeably subtle compared to other ophthalmologic diseases. Therefore, raw cross-sectional OCTs are replaced with multilayer segmented OCTs for discrimination of MS and healthy controls (HCs). To conform to the principles of trustworthy AI, interpretability is provided by visualizing the regional layer contribution to classification performance with the proposed occlusion sensitivity approach. The robustness of the classification is also guaranteed by showing the effectiveness of the algorithm while being tested on the new independent dataset. The most discriminative features from different topologies of the multilayer segmented OCTs are selected by the dimension reduction method. Support vector machine (SVM), random forest (RF), and artificial neural network (ANN) are used for classification. Patient-wise cross-validation (CV) is utilized to evaluate the performance of the algorithm, where the training and test folds contain records from different subjects. The most discriminative topology is determined to square with a size of 40 pixels and the most influential layers are the ganglion cell and inner plexiform layer (GCIPL) and inner nuclear layer (INL). Linear SVM resulted in 88% Accuracy (with standard deviation (std)=0.49 in 10 times of execution to indicate the repeatability), 78% precision (std=1.48), and 63% recall (std=1.35) in the discrimination of MS and HCs using macular multilayer segmented OCTs. The proposed classification algorithm is expected to help neurologists in the early diagnosis of MS. This paper distinguishes itself from other studies by employing two distinct datasets, which enhances the robustness of its findings in comparison with previous studies with lack of external validation. This study aims to circumvent the utilization of deep learning methods due to the limited quantity of the available data and convincingly demonstrates that favorable outcomes can be achieved without relying on deep learning techniques.

Stellate Multiform Amelanotic Choroidopathy (SMACH). Clinical and Multimodal Imaging Features.

To describe the clinical and multimodal imaging features of stellate multiform amelanotic choroidopathy (SMACH; also known as serous maculopathy due to aspecific choroidopathy). Retrospective observational case series of eyes presenting with SMACH. Multimodal imaging including fundus photography, optical coherence tomography (OCT), OCT-angiography (OCTA), and indocyanine green angiography (ICGA) was analyzed. Eighteen eyes from 18 patients (mean age: 28±19 years) were included. The mean follow-up duration was 9 years. Ophthalmoscopy showed a yellowish-orange, dendriform choroidal lesion. At presentation, subretinal fluid (SRF) was seen in 10/18 cases (56%). Eight patients (44%) showed no evidence of SRF during a mean follow-up of 6 years. Cross-sectional OCT showed hyperreflective fibrous-like changes within the inner choroid with choriocapillaris flow preservation on OCTA. En face OCT showed a hyperreflective choroidal lesion with finger-like projections oriented in a stellate configuration. On ICGA, SMACH showed early and late hypofluorescence. None of the cases showed lesion growth. SMACH appears to be a unilateral choroidopathy characterized by distinctive multimodal imaging features. As SRF was absent in some cases, while a dendriform pattern was a consistent finding in all eyes, we propose renaming this entity "stellate multiform amelanotic choroidopathy", a name which retains its prior abbreviation "SMACH".

Characteristics of Clinically Classified Oral Lichen Planus in Optical Coherence Tomography: A Descriptive Case-Series Study.

Malignant transformation of oral lichen planus (OLP) into oral squamous cell carcinoma is considered as one of the most serious complications of OLP. For the early detection of oral cancer in OLP follow-up, accurate localization of the OLP center is still difficult but often required for confirmatory biopsy with histopathological examination. Optical coherence tomography (OCT) offers the potential for more reliable biopsy sampling in the oral cavity as it is capable of non-invasively imaging the degenerated oral layer structure. In this case-series study with 15 patients, features of clinically classified forms of OLP in OCT cross-sections were registered and correlated with available histologic sections. Besides patients with reticular, atrophic, erosive and plaque-like OLP, two patients with leukoplakia were included for differentiation. The results show that OCT yields information about the epithelial surface, thickness and reflectivity, as well as the identifiability of the basement membrane and the vessel network, which could be used to complement the visual clinical appearance of OLP variants and allow a more accurate localization of the OLP center. This forms the basis for further studies on OCT-assisted non-invasive clinical classification of OLP, with the aim of enabling decision support for biopsy sampling in the future.

Poroelastic behavior of skin tissue in response to pressure driven flow

Better understanding of skin tissue's permeability and poroelasticity could help advance biomedical technologies concerning skin such as intradermal injection and grafting. We applied a pressure driven fluid flow across skin tissue's epidermal and dermal layers in a simple one-dimensional configuration, while measuring the resulting flow rate and capturing cross sectional optical coherence tomography (OCT) images of the tissue's deformation. Digital image correlation was used to analyze the OCT images and via a novel method, image analysis corrected for the change in the tissue's refractive index, which occurred due to flow-induced deformation, thus providing accurate one-dimensional depth-wise deformation profiles. Skin tissue was found to exhibit a nonlinear relationship between pressure and the resulting fluid flow rate, where the increase in flow rate with pressure decreased as pressure increased. The skin tissue was observed to experience compressive strain closest to the supported base, with magnitudes increasing with increasing driving pressure, and the tissue near the free surface experienced relatively little strain. Permeability was found to follow an exponential permeability-volumetric strain relationship with material constants: k0 (initial uniform permeability) of 9.6 × 10−15 m2 and m (extent of nonlinearity for the permeability–strain relationship) of 2.94. Darcy's law and the permeability–strain relationship were used to analyze results with good similarity between observed and calculated flowrates. This work presents a novel and direct method of characterizing soft tissue permeability and provides a fundamental understanding to skin behavior under pressurized driving fluid, which can be generalized to study or model other geometries of induced flow through skin tissue.

EVALUATION OF PARAVASCULAR INNER RETINAL DEFECTS USING EN FACE OPTICAL COHERENCE TOMOGRAPHY.

To evaluate the prevalence and risk factors for development of paravascular inner retinal defects (PIRDs) using en face optical coherence tomography. This is a retrospective cross-sectional study. En face and cross-sectional optical coherence tomography images were reviewed (9 × 9 mm or 12 × 12 mm). Paravascular inner retinal defects were classified as either Grade 1 (i.e., paravascular inner retinal cysts) when the lesion was confined within the nerve fiber layer without any communication to the vitreous cavity or Grade 2 (i.e., paravascular lamellar hole) when the defects communicated to the vitreous. Paravascular inner retinal defect grading was correlated with presence of high myopia, stage of posterior vitreous detachment, and presence of epiretinal membrane and retinoschisis. Of 1,074 patients (2,148 eyes), PIRDs were detected in 261 eyes with a prevalence of 261 per 2,148 eyes (12.2%) and 176 per 1,074 patients (16.4%). A total of 116 eyes (44.4%) displayed Grade 2 PIRDs while 145 eyes (55.6%) were Grade 1. In the multivariate logistic regression model, the presence of partial/complete posterior vitreous detachment, retinoschisis, and epiretinal membrane was significantly correlated with PIRDs (OR = 2.78 [1.7-4.4], P < 0.001; OR = 2.93 [1.7-5], P < 0.001; and OR = 25.9 [2.8-242.5], P < 0.001, respectively). The presence of partial/complete posterior vitreous detachment and epiretinal membrane was also significantly associated with Grade 2 PIRDs versus Grade 1 PIRDs ( P = 0.03 and P < 0.001). Our results indicate that wide-field en face optical coherence tomography facilitates the identification of PIRDs over a large area of retina with a single capture. The presence of PIRDs was significantly associated with posterior vitreous detachment, epiretinal membrane, and retinoschisis, confirming the role of vitreoretinal traction in the pathogenesis of PIRDs.

Investigation of the Influence of Pulse Duration and Application Mode on Microsecond Laser Microsurgery of the Retinal Pigment Epithelium.

Optical microsurgery confined to the retinal pigment epithelium (RPE) requires locally optimized laser parameters and reliable real-time feedback dosimetry (RFD) to prevent unwanted neuroretinal overexposure. This study aimed to compare pulses of different durations and application modes (single, ramp, burst). Moreover, optical coherence tomography (OCT)-based RFD was investigated in an ex vivo experiment, utilizing nine porcine eyes that were exposed to laser pulses of 8, 12, 16 and 20 µs duration (wavelength: 532 nm, exposure area: 90 × 90 µm2, radiant exposure: 247 to 1975 mJ/µm2). Simultaneously, time-resolved OCT M-scans were recorded (central wavelength: 870 nm, scan rate: 85 kHz) for RFD. Post irradiation, retinal changes were assessed with color fundus photography (CFP) and cross-sectional OCT B-scans. RPE cell damage was quantified via fluorescence-based cell viability assay and compared to the OCT dosimetry feedback. Our experiments indicate cumulative RPE damage for pulse bursts of 16 µs and 20 µs, whereas no cumulative effects were found for pulse durations of 8 µs and 12 µs applied in ramp mode. According to statistical analysis, OCT-RFD correctly detected RPE cell damage with 96% sensitivity and 97% specificity using pulses of 8 µs duration in ramp mode.

Calcium Fracture After Intravascular Lithotripsy as Assessed With Optical Coherence Tomography.

Plaque characteristics associated with effective intravascular lithotripsy (IVL) treatment of calcification have not been investigated. This study identified calcified plaque characteristics that favor the use of IVL.Methods and Results: Optical coherence tomography (OCT) was performed in 16 calcified lesions in 16 patients treated with IVL and coronary stenting. Cross-sectional OCT images in 262 segments matched across pre-IVL, post-IVL, and post-stenting time points were analyzed. After IVL, 66 (25%) segments had calcium fracture. In multivariable analysis, calcium arc (odds ratio [OR] 1.22; 95% confidence interval [CI] 1.13-1.32; P<0.0001), superficial calcification (OR 6.98; 95% CI 0.07-55.57; P=0.0182), minimum calcium thickness (OR 0.66; 95% CI 0.51-0.86; P=0.0013), and nodular calcification (OR 0.24; 95% CI 0.08-0.70; P=0.0056) were associated with calcium fracture. After stenting, stent area was larger for segments with fracture (8.0 [6.9-10.6] vs. 7.1 [5.2-8.9] mm2; P=0.004). Post-IVL calcium fracture is more likely in calcified lesions with lower thickness, a larger calcium arc, superficial calcification, and non-nodular calcification, leading to a larger stent area.

An AI model to estimate visual acuity based solely on cross-sectional OCT imaging of various diseases.

To develop an artificial intelligence (AI) model for estimating best-corrected visual acuity (BCVA) using horizontal and vertical optical coherence tomography (OCT) scans of various retinal diseases and examine factors associated with its accuracy. OCT images and associated BCVA measurements from 2,700 OCT images (accrued from 2004 to 2018 with an Atlantis, Triton; Topcon, Tokyo, Japan) of 756 eyes of 469 patients and their BCVA were retrospectively analysed. For each eye, one horizontal and one vertical OCT scan in cross-line mode were used. The GoogLeNet architecture was implemented. The coefficient of determination (R2), root mean square error (RMSE) and mean absolute error (MAE) were computed to evaluate the performance of the trained network. R2, RMSE, and MAE were 0.512, 0.350, and 0.321, respectively. R2 was higher in phakic eyes than in pseudophakic eyes. Multivariable regression analysis showed that a higher R2 was significantly associated with better BCVA (p < 0.001) and a higher standard deviation of BCVA (p < 0.001). However, the performance was worse in an external validation, with R2 of 0.19. R2 values for retinal vein occlusion and age-related macular degeneration were 0.961 and 0.373 in the internal validation but 0.20 and 0.22 in the external validation. Although underspecification appears to be a fundamental problem to be addressed in AI models for predicting visual acuity, the present results suggest that AI models might have potential for estimating BCVA from OCT in AMD and RVO. Further research is needed to improve the utility of BCVA estimation for these diseases.

Predicting Visual Outcome Following Surgery in Patients with Idiopathic Epiretinal Membrane Using A Novel Convolutional Neural Network.

To develop a deep convolutional neural network (CNN) that enables the prediction of postoperative visual outcomes following epiretinal membrane (ERM) surgery based on preoperative optical coherence tomography (OCT) images and clinical parameters to refine surgical decision-making. A total of 529 patients with idiopathic ERM who underwent standard vitrectomy with ERM peeling surgery by two surgeons between January 1, 2014, and June 1, 2020, were enrolled. The newly developed Heterogeneous Data Fusion Net (HDF-Net) was introduced to predict postoperative visual acuity (VA) outcomes (improvement ≥ 2 lines in Snellen chart or not) 12 months after surgery based on preoperative cross-sectional OCT images and clinical factors, including age, sex, and preoperative VA. The predictive accuracy, sensitivity, specificity, and area under the receiver operating characteristic curve (AUC) of the CNN model were evaluated. The developed model demonstrated an overall accuracy for visual outcome prediction of 88.68% (95% CI, 79.0%-95.7%) with an AUC of 97.8% (95% CI, 86.8%-98.0%), sensitivity of 87.0% (95% CI, 67.9%-95.5%), specificity of 92.9% (95% CI, 77.4%-98.0%), precision of 0.909, recall of 0.870, and F1 score of 0.889. The heatmaps identified the critical area for prediction as the ellipsoid zone of photoreceptors and the superficial retina which was subjected to tangential traction of the proliferative membrane. The novel HDF-Net demonstrated high accuracy in the automated prediction of visual outcomes after weighing and leveraging multiple clinical parameters, including OCT images. This approach may be helpful in establishing personalized therapeutic strategies for ERM management.

Prediction of the Functional Result of Surgery for the Full Thickness of the Macular Hole Based on the Analysis of the Safety of Retinal Tissue

Purpose. To study the relationship between baseline optical coherence tomography (OCT) characteristics of preservation of the neurosensory retina and retinal pigment epithelium (RPE) and functional outcome after full thickness macular hole (FTHM) surgery.Materials and methods. Patients with complete postoperative anatomical closure of the FTMH were included in this prospective interventional study. All patients received a standard ophthalmological examination and OCT before surgical treatment. At baseline the area and reflectivity of the neurosensory retina at the edges of the hole was measured on cross-sectional OCT scans. The reflectivity of RPE was evaluated within the hole on structural en face projections of RPE slab. Six months postoperatively, correlation between baseline OCT characteristics and visual outcome was evaluated.Results. Twenty-nine patients (30 eyes, 23 females and 6 males, average age — 66.2 ± 5.2 years) were included in the study. The final best-corrected visual acuity showed a statistically significant correlation with baseline best-corrected visual acuity (r = 0.75, p &lt; 0.001), reflectivity of RPE (r = 0.81, p &lt; 0.001), reflectivity of neurosensory retina (r = –0.88, p &lt; 0.001), and its area (r = 0.41, p = 0.02).Conclusion. OCT-characteristics of retinal tissue preservation, including the area and reflectivity of the neurosensory retina and reflectivity of the RPE within the hole, correlate with functional recovery after FTMH surgery.