Spectral-domain Optical Coherence Tomography Device Research Articles

Optical coherence tomography choroidal enhancement using generative deep learning

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

Attention flexibility is associated with retinal cup-to-disk ratio in patients with schizophrenia spectrum disorders

IntroductionIn recent years, there has been increasing interest in the potential use of retinal imaging as a non-invasive and easily accessible tool for investigating the neurobiological underpinnings of schizophrenia. Studies have suggested that patients with schizophrenia spectrum disorders (SSD) have structural abnormalities in the retina, including changes in retinal thickness and the ratio of the retinal cup-to-disk ratio.ObjectivesTo investigate the relationship between retinal cup-to-disk ratio and cognitive performance in patients with SSD using a high-definition retinal imaging device – optical coherence tomography (OCT) scanner.MethodsThe sample was comprised of twenty patients with SSD (F20-F29 according to ICD-10 criteria). All diagnoses were confirmed by a researcher using the Mini International Psychiatric Interview. All patients underwent complete ophthalmological examination, excluding any ocular pathology. Retinal thickness was measured in both eyes of all patients with a high-definition spectral-domain OCT device. Examined retinal parameters were: total retinal nerve fiber layer thickness (RNFL); RNFL thickness in all eye quadrants (nasal, temporal, superior, inferior); RNFL symmetry; average macular volume (MV); average macular thickness (MT); ganglion cell layer thickness (GC); average retinal cup-to-disk (C/D) ratio, vertical C/D ratio. Cognitive performance of all patients was tested using the Intra/Extradimensional Set Shift Task (IED). IED is a component of a state-of-the-art computerized battery for cognitive assessment – Cambridge Neuropsychological Automated Test Battery. IED is a measure of maintenance, shifting and flexibility of attention. Associations between retinal variables and IED measures were determined with Pearson correlation analyses.ResultsMean age of patients was 33 ± 7.5 years. Fifty five percent of the sample was male, illness duration was 6.2 ± 3.9 years. Daily dosage of chlorpromazine was 225.7 ± 108.8 mg. Retinal C/D ratio in the right eye was positively associated with IED total errors (r=0.50; p=0.02) and negatively with IED stage progression (r=-0.52, p=0.18). Likewise, vertical C/D ratio was positively associated with IED total errors (r=0.49; p=0.02) and negatively with IED stage progression (r=-0.52, p=0.18).ConclusionsPrevious analyses of retinal parameters in patients with schizophrenia point towards enlargement of retinal cup-to-disk ratio, irrespective of any underlying somatic comorbidities. Our data shows worsening of attention flexibility in association with the increase of cup-to-disk ratio in patients with schizophrenia spectrum disorders. The significance of cup-to-disk retinal disturbance in schizophrenia spectrum disorders and its connection with cognitive performance should be further evaluated and supplemented with measurements of functional adaptation in these patients.Disclosure of InterestNone Declared

Assessing the impact of internal carotid artery stenosis on choroidal thickness using Cirrus optical coherence tomography

Aims: The choroid, one of the body's most highly vascularized tissues, receives its blood supply from the ophthalmic and posterior ciliary arteries, which stem from the internal carotid artery. The utilization of spectral-domain optical coherence tomography (SD-OCT) for both qualitative and quantitative assessment of the retina is increasing. The recent introduction of enhanced depth imaging OCT (EDI-OCT) has offered a novel approach to evaluate the choroid using commercially accessible SD-OCT devices. EDI-OCT enables the in vivo examination and measurement of the choroid. The main objective of our study is to evaluate choroidal thickness using EDI-OCT in patients with unilateral significant carotid stenosis; the secondary objective is to observe whether hemodynamic changes affect choroidal thickness. Methods: The study is prospectively designed as a cross-sectional, controlled, and single-blind study, encompassing patients who underwent neck computed tomographic angiography within a one-year period due to any disease. Included patients had carotid stenosis of 50% or more on one side and less than 50% on the other side. The eyes on the side with higher carotid stenosis constituted the study group, while the other side formed the control group. Anterior and posterior segment examinations of the patients, visual acuity according to Snellen Chart, and choroidal thickness were measured. Results: A total of 30 eyes of 15 patients were evaluated. Of the patients included in the study, 9 were men and 6 were women; the average age was 67.9 years (49-85). In the study group, the average choroidal thickness measurements were 211 µm in the nasal, 221 µm in the central and 209 µm in the temporal; in the control group, they were measured as 223 µm in the nasal, 243 µm in the central, and 231 µm in the temporal, respectively. Despite the choroidal thickness being thinner in the study group, the difference did not reach statistical significance. Conclusion: Additional research is required to pinpoint the factors contributing to the dynamics of choroidal thickness and to delineate its significance in carotid artery stenosis more comprehensively.

Normative retinal nerve fiber layer thickness in a healthy pediatric South Asian cohort: a spectral-domain optical coherence tomography study.

Currently, the normative values for retinal nerve fiber layer (RNFL) thickness in our population have not been widely studied. Our study aimed to assess the peripapillary RNFL thickness (RNFLT) with Optopol Copernicus REVO80® spectral-domain optical coherence tomography (SD-OCT) amongst healthy children and its associations. One hundred eighty-two eyes of 91 consecutive healthy children 3 to 16 years of age with a refractive error ≤ ± 5 D were included after a thorough eye exam including visual acuity, refraction, tonometry, pachymetry, axial length estimation, and slit lamp exam including fundus assessment. RNFLT was measured via Optopol Copernicus REVO80® high resolution SD-OCT by a single experienced observer with 3D disc mode within a circular area of diameter 3.45 mm and the ring further divided into four quadrants: inferior, superior, nasal, and temporal. The mean age was 11.12 ± 3.12 years (range, 3-16). The average RNFLT was 120.13 ± 12.6 μm. The mean superior RNFL was the thickest at 138.21 ± 16.6 μm, next was the mean inferior RNFLT at 137.62 ± 17.2 μm, followed by the nasal 91.61 ± 18.5 μm and then the temporalat 74.58 ± 11.7 μm. No significant differences in RNFLT were noted between the two eyes. The mean RNFLT was significantly higher in males as compared to females, in vertical quadrants and at an average (p < 0.05). No significant relationship was found between the average RNFLT and factors such as age, axial length, corneal thickness, cup-to-disc ratio, intraocular pressure, or refractive error. This study establishes normative values of RNFLT for this subgroup of Pakistani children for the Optopol Copernicus REVO80® SD-OCT device.

A new method for in vivo assessment of corneal transparency using spectral-domain OCT.

Corneal transparency is essential to provide a clear view into and out of the eye, yet clinical means to assess such transparency are extremely limited and usually involve a subjective grading of visible opacities by means of slit-lamp biomicroscopy. Here, we describe an automated algorithm allowing extraction of quantitative corneal transparency parameters with standard clinical spectral-domain optical coherence tomography (SD-OCT). Our algorithm employs a novel pre-processing procedure to standardize SD-OCT image analysis and to numerically correct common instrumental artifacts before extracting mean intensity stromal-depth (z) profiles over a 6-mm-wide corneal area. The z-profiles are analyzed using our previously developed objective method that derives quantitative transparency parameters directly related to the physics of light propagation in tissues. Tissular heterogeneity is quantified by the Birge ratio Br and the photon mean-free path (ls) is determined for homogeneous tissues (i.e., Br~1). SD-OCT images of 83 normal corneas (ages 22-50 years) from a standard SD-OCT device (RTVue-XR Avanti, Optovue Inc.) were processed to establish a normative dataset of transparency values. After confirming stromal homogeneity (Br <10), we measured a median ls of 570 μm (interdecile range: 270-2400 μm). By also considering corneal thicknesses, this may be translated into a median fraction of transmitted (coherent) light Tcoh(stroma) of 51% (interdecile range: 22-83%). Excluding images with central saturation artifact raised our median Tcoh(stroma) to 73% (interdecile range: 34-84%). These transparency values are slightly lower than those previously reported, which we attribute to the detection configuration of SD-OCT with a relatively small and selective acceptance angle. No statistically significant correlation between transparency and age or thickness was found. In conclusion, our algorithm provides robust and quantitative measurements of corneal transparency from standard SD-OCT images with sufficient quality (such as 'Line' and 'CrossLine' B-scan modes without central saturation artifact) and addresses the demand for such an objective means in the clinical setting.

Is preclinical diabetic retinopathy in diabetic nephropathy individuals more severe?

To analyse the retinal vessel density and thickness characteristics of diabetic nephropathy (DN) individuals with preclinical diabetic retinopathy (DR) using optical coherence tomography angiography (OCTA). This retrospective case-control study included 88 eyes of 88 type 2 DM patients with preclinical DR [44 non-DN (NDN) and 44 DN]. OCTA images and data were acquired using AngioVue 2.0 of the spectral domain OCT device. The foveal avascular zone (FAZ) area, superficial capillary plexus (SCP) and deep capillary plexus vessel densities, ganglion cell complex (GCC) and full retinal thicknesses, peripapillary capillary density and nerve fibre layer (RNFL) thickness were compared between the NDN and DN groups. The relationship between each renal function parameter and each OCTA parameter was analysed. SCP vessel density, GCC thickness and full retinal thickness were significantly reduced in DN individuals compared to NDN individuals [(NDN versus DN) SCP vessel density: 46.65 ± 3.84% versus 44.35 ± 5.25%, p=0.030; GCC thickness: 100.79 ± 5.92 μm versus 93.28 ± 8.66 μm, p<0.001; full retinal thickness: whole area: 287.04 ± 13.62 μm versus 277.71 ± 15.10 μm, p=0.005). Within the peripapillary area, capillary density was also significantly reduced in the whole area (50.19 ± 3.10% versus 47.46 ± 5.93%, p=0.016) and some sectors in the DN group, though RNFL thickness was only decreased in some sectors. For all individuals, estimated glomerular filtration rate (eGFR) correlated significantly with most OCTA parameters and then showed a significantly negative correlation with FAZ area (β=-16.43, p=0.039) in multivariate linear regression analysis. In the NDN group, eGFR showed a significantly negative correlation with FAZ area (β=-18.746, p=0.048) and a significantly positive correlation with SCP vessel density (β=0.580, p=0.036). Preclinical DR may be more severe in DN individuals than in NDN individuals with regard to microvascular and microstructural impairment. Moreover, eGFR may be a good indicator for retinal microvascular impairment.

Three-Dimensional Multi-Task Deep Learning Model to Detect Glaucomatous Optic Neuropathy and Myopic Features From Optical Coherence Tomography Scans: A Retrospective Multi-Centre Study

PurposeWe aim to develop a multi-task three-dimensional (3D) deep learning (DL) model to detect glaucomatous optic neuropathy (GON) and myopic features (MF) simultaneously from spectral-domain optical coherence tomography (SDOCT) volumetric scans.MethodsEach volumetric scan was labelled as GON according to the criteria of retinal nerve fibre layer (RNFL) thinning, with a structural defect that correlated in position with the visual field defect (i.e., reference standard). MF were graded by the SDOCT en face images, defined as presence of peripapillary atrophy (PPA), optic disc tilting, or fundus tessellation. The multi-task DL model was developed by ResNet with output of Yes/No GON and Yes/No MF. SDOCT scans were collected in a tertiary eye hospital (Hong Kong SAR, China) for training (80%), tuning (10%), and internal validation (10%). External testing was performed on five independent datasets from eye centres in Hong Kong, the United States, and Singapore, respectively. For GON detection, we compared the model to the average RNFL thickness measurement generated from the SDOCT device. To investigate whether MF can affect the model’s performance on GON detection, we conducted subgroup analyses in groups stratified by Yes/No MF. The area under the receiver operating characteristic curve (AUROC), sensitivity, specificity, and accuracy were reported.ResultsA total of 8,151 SDOCT volumetric scans from 3,609 eyes were collected. For detecting GON, in the internal validation, the proposed 3D model had significantly higher AUROC (0.949 vs. 0.913, p < 0.001) than average RNFL thickness in discriminating GON from normal. In the external testing, the two approaches had comparable performance. In the subgroup analysis, the multi-task DL model performed significantly better in the group of “no MF” (0.883 vs. 0.965, p-value < 0.001) in one external testing dataset, but no significant difference in internal validation and other external testing datasets. The multi-task DL model’s performance to detect MF was also generalizable in all datasets, with the AUROC values ranging from 0.855 to 0.896.ConclusionThe proposed multi-task 3D DL model demonstrated high generalizability in all the datasets and the presence of MF did not affect the accuracy of GON detection generally.

LamNet: A Lesion Attention Maps-Guided Network for the Prediction of Choroidal Neovascularization Volume in SD-OCT Images.

Choroidal neovascularization (CNV) volume prediction has an important clinical significance to predict the therapeutic effect and schedule the follow-up. In this paper, we propose a Lesion Attention Maps-Guided Network (LamNet) to automatically predict the CNV volume of next follow-up visit after therapy based on 3-dimentional spectral-domain optical coherence tomography (SD-OCT) images. In particular, the backbone of LamNet is a 3D convolutional neural network (3D-CNN). In order to guide the network to focus on the local CNV lesion regions, we use CNV attention maps generated by an attention map generator to produce the multi-scale local context features. Then, the multi-scale of both local and global feature maps are fused to achieve the high-precision CNV volume prediction. In addition, we also design a synergistic multi-task predictor, in which a trend-consistent loss ensures that the change trend of the predicted CNV volume is consistent with the real change trend of the CNV volume. The experiments include a total of 541 SD-OCT cubes from 68 patients with two types of CNV captured by two different SD-OCT devices. The results demonstrate that LamNet can provide the reliable and accurate CNV volume prediction, which would further assist the clinical diagnosis and design the treatment options.

Retinal thickness profiles in patients with Behçet uveitis during remission.

The purpose of this study was to evaluate the intraretinal layer thickness in the macular region and its correlation with the duration of uveitis and visual acuity in patients with Behçet uveitis. In this cross-sectional study, we included 93 eyes of 57 patients with Behçet uveitis and 100 eyes of 50 healthy individuals admitted to a tertiary center from January to September 2017. We performed macular measurements in all subjects via spectral domain-optical coherence tomography (SD-OCT) and divided the retina into layers using automated segmentation software on the SD-OCT device. We then compared layer thicknesses between the patient and control groups and evaluated the correlation between OCT parameters and the duration of uveitis and visual acuity in the patient group. Our records show a mean age of 37.9 ± 10.8 (18-64) years and 37.7 ± 12.2 (21-61) years in the patient and control groups (p=0.821), respectively. Meanwhile, data reveal a mean duration of uveitis of 6.9 ± 4.7 (1-20) years. We found a reduction in the total outer layer thickness in the patient group (p<0.001). However, we did not find a statistically significant difference in the inner retinal layers except in the inner nuclear layer. The duration of uveitis negatively correlated with the outer retinal layer's thickness (correlation coefficient = -0.250). On the other hand, visual acuity positively correlated with the central macular, the total inner layer, and the outer retinal layer thicknesses (correlation coefficients: 0.194, 0.154, and 0.364, respectively). However, the inner nuclear layer negatively correlated with visual acuity. Using retinal segmentation via SD-OCT for follow-ups can help estimate visual loss in patients with Behçet uveitis, which can cause significant changes in intraretinal layers in the macular region.

An Optical Coherence Tomography Study that Supports the Neurovascular Basis of Schizophrenia Disease.

Spectral domain optical coherence tomography (SD-OCT) is a non--penetrating, quick, and practical device which enables measurement of the chorioretinal layers. In this study, our purpose was to investigate the retinal nerve fiber layer (RNFL) and choroidal thickness in schizophrenia patients, using SD-OCT, and compare the -findings with those of the control group. For the study, 44 patients with a diagnosis of schizophrenia, and 41 age- and gender- matched healthy controls were enrolled. Both eyes of each participant were -evaluated. RNFL was measured and analyzed automatically with optical coherence tomography. Scans for choroidal thickness were obtained with the enhanced depth imaging mode of the SD-OCT device and measured manually. The average age of schizophrenia patients was 47.82, and it was 45.5 for the control group. The mean illness duration of the patients was 24.79 years. According to the results of this study, all choroidal measures (nasal, subfoveal, and temporal) of both eyes, and the RNFL thickness of schizophrenia patients, were significantly thinner than that of healthy controls. The chorioretinal measures of both eyes were similar. The results showed that a weak negative correlation was present between illness duration and choroidal diameter. In addition to demonstrating the thinning of RNFL in schizophrenia patients, as frequently reported in the literature, the results of this study show, for the first time, that choroidal thickness is considerably decreased in schizophrenia patients compared to the healthy controls, using SD-OCT. Keeping in mind that the choroid is a vascular layer, these results support the neurovascular hypothesis of schizophrenia.

Posterior Pole Asymmetry Analysis in the Children with Anisometropia.

Objectives:The objectives of the study were to investigate the inter and intraocular differences in posterior pole asymmetry analysis (PPAA) with optical coherence tomography (OCT) in anisometropia, to examine the relationship between the presence of anisometropia and amblyopia and retinal thickness.Methods:Patients between ages of 5 and 16 years with anisometropia who applied to our clinic were included in the study. Macular retinal thickness measurements were evaluated by PPAA using the posterior pole algorithm of the spectral domain-OCT device. Asymmetry was analyzed both as the difference between the right and left eyes and the difference between the superior, inferior, and mean retinal thicknesses of 64 separate quadrants in the same eye. Hemispheric and right-left eye asymmetry differences analyses were performed.Results:118 patients were included in the study(65 females and 53 males). Group 1 consisted of anisometropic patients (n=46), Group 2 consisted of anisometropic amblyopia patients (n=40), and Group 3 consisted of control group (n=32). The mean age of the patients was 9.72±5.6 years. The mean spherical equivalent difference between the two eyes of the patients was 1.7±0.6 D. When anisometropic eyes were compared with normal eyes, there was no significant difference between mean superior, inferior and total retinal thickness, and right-left eye asymmetry values (for all, p>0.05). In the asymmetry evaluation performed by counting the black boxes in the PPAA, a significant difference was found in the right-left asymmetry evaluation in anisometropic amblyopic eyes, in some quadrants and in the right-left asymmetry analysis (p<0.05).Conclusion:While no difference was found between anisometropic and normal eyes in the PPAA, there was differences in some quadrants in the anisometropic amblyopic group compared to the control group suggesting that there is an involvement in the peripheral quadrants of the macula, especially in treatment resistant amblyopic patients.

Prospective, Longitudinal Pilot Study: Daily Self-Imaging with Patient-Operated Home OCT in Neovascular Age-Related Macular Degeneration.

PurposeTo evaluate longitudinally the performance of the Notal Vision Home OCT (NVHO), comprising a spectral-domain OCT device for patient self-imaging at home, telemedicine infrastructure for automated data upload, and deep learning algorithm for automated OCT evaluation. The aims were to study the system’s performance in daily image acquisition and automated analysis and to characterize the dynamics of retinal fluid exudation in neovascular age-related macular degeneration (nAMD).DesignPilot prospective, observational longitudinal study.ParticipantsFour individuals (mean age, 73.8 years) with nAMD (one or both eyes) undergoing anti–vascular endothelial growth factor therapy in routine clinical practice.MethodsThe participants performed daily self-imaging at home with the NVHO for 1 month. The macular cube scans were uploaded automatically to the Notal Health Cloud. They underwent evaluation separately by the Notal OCT Analyzer (NOA) and human expert graders for fluid presence, segmentation, and volume.Main Outcome MeasuresDaily self-imaging completion, image quality, acquisition time, agreement between automated and human grading of retinal fluid, and temporal dynamics of fluid volume.ResultsOf 240 self-imaging attempts initiated, the number successfully completed was 211 (87.9%). Of these, 97.6% had satisfactory quality. For fluid presence, the NOA agreed with human grading in 94.7% of cases. From a subset of 24 scans with fluid, for agreement between NOA and human fluid volume measurements, the correlation coefficient was 0.996 and mean absolute difference was 1.5 nl (vs. 0.995 and 1.2 nl, respectively, for interhuman agreement). Graphic plots of fluid volume revealed wide variation in the dynamics of fluid exudation and treatment response.ConclusionsThe participants could perform daily self-imaging at home and generate macular cube scans of satisfactory quality. Automated quantitative OCT analysis achieved high agreement with human grading. Daily self-imaging with automated OCT analysis permitted detailed characterization of the dynamics of fluid exudation and revealed wide variation between eyes. Metrics describing these dynamics may become important disease biomarkers. Home OCT telemedicine systems represent an alternative paradigm of disease monitoring; they may allow highly personalized retreatment decisions, with fewer unnecessary injections and clinic visits.

Non-invasive three-dimensional thickness analysis of oral epithelium based on optical coherence tomography—development and diagnostic performance

ObjectivesEvaluating structural changes in oral epithelium can assist with the diagnosis of cancerous lesions. Two-dimensional (2D) non-invasive optical coherence tomography (OCT) is an established technique for this purpose. The objective of this study was to develop and test the diagnostic accuracy of a three-dimensional (3D) evaluation method. MethodsThe oral lip mucosa of 10 healthy volunteers was scanned using an 870-nm spectral-domain OCT device (SD-OCT) with enhanced depth imaging (EDI). Four raters semi-automatically segmented the epithelial layer twice. Thus, eighty 3D datasets were created and analyzed for epithelial thickness. To provide a reference standard for comparison, the raters took cross-sectional 2D measurements at representative sites. The correlation between the 2D and 3D measurements, as well as intra- and inter-rater reliability, were analyzed using intraclass correlation coefficients (ICC). ResultsMean epithelial thickness was 280 ± 64μm (range 178–500 μm) and 268 ± 49μm (range 163–425 μm) for the 2D and 3D analysis, respectively. The inter-modality correlation of the thickness values was good (ICC: 0.76 [0.626–0.846]), indicating that 3D analysis of epithelial thickness provides valid results. Intra-rater and inter-rater reliability were good (3D analysis) and excellent (2D analysis), suggesting high reproducibility. ConclusionsDiagnostic accuracy was high for the developed 3D analysis of oral epithelia using non-invasive, radiation-free OCT imaging. Clinical significanceThis new 3D technique could potentially be used to improve time-efficiency and quality in the diagnosis of epithelial lesions compared with the 2D reference standard.

Eye motion correction algorithm for OCT-based corneal topography.

With its sequential image acquisition, OCT-based corneal topography is often susceptible to measurement errors due to eye motion. We have developed a novel algorithm to detect eye motion and minimize its impact on OCT topography maps. We applied the eye motion correction algorithm to corneal topographic scans acquired using a 70 kHz spectral-domain OCT device. OCT corneal topographic measurements were compared to those from a rotating Scheimpflug camera topographer. The motion correction algorithm provided a 2-4 fold improvement in the repeatability of OCT topography and its agreement with the standard Scheimpflug topographer. The repeatability of OCT Zernike-based corneal mean power, cardinal astigmatism, and oblique astigmatism after motion detection was 0.14 D, 0.28 D, and 0.24 D, respectively. The average differences between the two devices were 0.19 D for simulated keratometry-based corneal mean power, 0.23 D for cardinal astigmatism, and 0.25 D for oblique astigmatism. Our eye motion detection method can be applied to any OCT device, and it therefore represents a powerful tool for improving OCT topography.

Normal Reference Ranges of Optical Coherence Tomography Parameters in Children.

To measure the macular thickness, macular volume and peripapillary retinal nerve fiber layer (RNFL) in healthy Caucasian chil-dren using spectral domain optical coherence tomography (SDOCT) and analyze the correlation of these values with age, refraction, and biometric measurements. In this cross-sectional study, we recruited 270 healthy children (150 female and 120 male) aged 6 to 17 years with no ocular abnormalities. All children underwent a detailed eye examination. The measurements were obtained using a SDOCT device (SOCT Copernicus REVO). Main outcome measures were macular thickness, macular volume and RNFL thickness. Their correlations with age, refractive error, anterior chamber depth (ACD) and axial length (AL) was analyzed. Right eyes of all subjects were selected for analysis. In this study group (mean age 10.70±2.82 years), the average peripapillary RNFL thickness was 117.11±9.15 μm, the central macular thickness was 232.10±15.81 μm, the average macular thickness was 286.70±9.82 μm, and the average macular volume was 8.01±0.28 mm³. The average values for the biometric data were: axial length - 23.16±0.94 mm, anterior chamber depth - 3.64±0.26 mm, the spherical equivalent (SE) value - +0.81±0.58 diopter. Central macular thickness, inner macular thickness (superior, inferior, nasal, temporal quadrants) values, total macular thickness and macular volume were significantly higher in males than in females. We found a positive correlation between central macular thickness, inner nasal macular thickness, outer inferior macular thickness values, and age. Also, we found a significant correlation between the average macular thickness values and the average macular volume values (p<0.0001). RNFL measurements did not correlate with age (p=0.199). Almost all macular parameters were consistently positively cor-related with SE. A significant correlation was also found between the central macular thickness, inner inferior macular thickness, inner nasal macular thickness and the ACD. We found a significant correlation between the average macular thickness, macular volume, inner superior macular thickness, outer macular thickness (superior, inferior, nasal, temporal quadrants) values and the AL. This study found normal reference ranges for RNFL and macular parameters measured by SOCT Copernicus REVO in healthy Caucasian children aged 6-17 years. This normative values could be very useful in early diagnosing and monitoring of optic neuropathy, glaucoma and macular diseases in childhood.

Optical coherence tomography reveals light-dependent retinal responses in Alzheimer’s disease

Spectral-domain optical coherence tomography (SD-OCT) is an accessible clinical tool for measuring structural changes to the retina, and increasingly as a biomarker for brain-predominant neurodegenerative diseases like Alzheimer’s. Information about retinal function can also be extracted from OCT images, but is under-studied, with literature examples often employing challenging protocols or requiring specialized hardware. The first goal of this study was to verify that functional retinal imaging was feasible with a commercially-available SD-OCT device and a clinically practical protocol. Inspired by methods from other functional imaging modalities, we acquired images while repeatedly cycling lights on and off, and spatially normalized retinas to facilitate intra- and inter-individual analyses. In eight healthy young adults, light-dependent increases in reflectivity were easily demonstrated at photoreceptor inner and outer segments, changing by ~7% in bright light and ~3% in dim light. Bright light elicited a subtle (~2%) but consistent light-dependent decrease in reflectivity through much of the rest of the retina, including the avascular outer nuclear layer (ONL). We speculated that some of these changes are influenced by glial function – as through water management – a topic of high interest in neurodegenerative diseases that may involve the glymphatic system. Functional abnormalities in patients with antibodies against aquaporin-4 (n ​= ​3) supported this interpretation. We next compared patients with early-onset Alzheimer’s disease (n ​= ​14) to age-matched controls (n ​= ​14), revealing that patients had a relatively exaggerated light-induced change in ONL reflectivity (p ​< ​0.05). Because these measurements can be obtained within 30 ​min, regular use in research and limited clinical settings is feasible.

T168. MACULAR THINNING IN FEMALE PATIENTS WITH PSYCHOSIS SPECTRUM DISORDERS: PRELIMINARY OPTICAL COHERENCE TOMOGRAPHY FINDINGS

BackgroundStructural retinal architecture in living organisms became measurable with the development of optical coherence tomography (OCT) scanners. Recent investigations identified thinning of individual retinal layers in psychosis spectrum disorders (PSD) [1]. Previous reports have shown that structural sex dimorphism of normal brain development is disturbed in psychosis [2]. To the best of our knowledge, no study has examined sex differences in retinal architecture in PSD.MethodsA total of 39 patients with psychosis spectrum disorders and 35 healthy controls matched by age and sex were included. The groups were further divided according to sex: male patients (MP; n=21), female patients (FP; n=18), male controls (MC; n=18), female controls (FC; n=17).A spectral-domain OCT device (Cirrus 4000, Carl Zeiss Inc.) was used to assess the thickness of retinal nerve fiber layer (RNFL), macular volume (MV), total macular thickness, mean and minimal ganglion cell-inner plexiform layer thickness (GC-IPL), optic cup volume and cup-to-disk ratio. Daily dosage of antipsychotic medication was calculated through chlorpromazine equivalents (CPZeq). Comparisons between the groups were performed with one-way ANOVA (Tukey post hoc), Student’s t-test, and chi-squared test.ResultsSociodemographic/clinical characteristics of the groups were as follows: MC – age 29.6 ± 6.4 years; FC – age 32.8 ± 12.1 years; MP – age 33.2 ± 6.0 years (duration of illness 7.3 ± 4.0 years, CPZeq 254.1 ± 153.19 mg) and FP – age 30.6 ± 6.9 year (duration of illness 5.3 ± 3.7 years, CPZeq 201.6 ± 96.2 mg). There were no significant differences in any of the given parameters.Assessment of retinal parameters showed: lower macular central subfield thickness in the right eye when FP and FC were compared (243.75 vs. 260.52 µm, respectively; p=0.03), while in the left eye it showed a similar trend (FP vs. FC, 246.00 vs. 261.11 µm, respectively; p=0.06). MV was lower when FP and FC were compared both in the right (10.00 vs. 10.40 mm3, respectively; p=0.03) and in the left eye (9.94 vs. 10.40 mm3, respectively; p=0.00). Differences were found in total macular thickness in FP vs. FC in both right (277.81 vs. 288.94 µm, respectively; p=0.02) and left eye (276.00 vs. 288.88 µm, respectively; p=0.00). No significant differences in any of the retinal parameters were found when MP were compared with MC.In MP negative correlations were observed between mean antipsychotic dose and the following retinal parameters: inferior RNFL quadrant in the left eye (r=-0.76, p=0.00), macular volume in the right eye (r=-0.60, p=0.03), total macular thickness in the right (r=-0.61, p=0.03) and left eye (r=-0.59, p=0.04) and minimum GC-IPL thickness in the right eye (r=-0.63, p=0.02). In FP, no associations between any of the parameters and antipsychotic dosages were found.DiscussionTo the best of our knowledge, relatively greater macular thinning in female patients with psychosis has not been reported before. Preclinical studies have shown that variability in individual retinal parameters could be influenced by the estrus cycle [3]. In this context, it has been suggested that women who are vulnerable to the development of PSD may have lower levels of endogenous estrogen in comparison to healthy women [4]. The importance of the menstrual phase in the interpretation of retinal thickness measurements in women during reproductive age is an important issue and should be taken into further consideration. Heterogeneous associations between antipsychotic dosages and retinal parameters need additional exploration. Further investigations of sex differences in PSD trough OCT-based measurements are needed in order to confirm and further clarify retinal sex differences in psychosis.

Optical coherence tomography angiography microvascular changes in diabetics without diabetic retinopathy.

PURPOSE:The purpose of this study was to analyze the retinal vasculature of diabetic eyes without clinical retinopathy in order to detect microvascular abnormalities, comparing them to that of healthy nondiabetic control eyes.METHODS:This is a prospective, cross-sectional study including 40 patients (76 eyes). Twenty patients (40 eyes) were diabetics with no diabetic retinopathy group (NDRG). The twenty other patients (36 eyes) were nondiabetic and constituted the control group (CG). Images were obtained using the AngioVue optical coherence tomography angiography (OCTA) software of RTVue XR spectral-domain OCT device. We performed 3 mm × 3 mm and 6 mm × 6 mm scans to evaluate the foveolar avascular zone (foveal) size, a remodeling of the FAZ, microaneurysms, vessel tortuosity, and superficial vascular density. All statistics were performed using IBM SPSS statistics (version 21).RESULTS:The average FAZ size was 314.6 ± 15.3 μm in the NDRG versus 291.5 ± 14.1 in the CG. The difference was not significant (P = 0.56). FAZ remodeling was noted in 40% of eyes in the NDRG and in 2.8% of eyes in the CG (P = 0.0001). Flow alteration zones (nonperfusion zones) were seen in 77.5% in the NDRG (P = 0.0001). Microaneurysms were present only in the NDRG (70% of eyes). Parafoveolar vascular density was 52.8% ± 0.7% in the NDRG and 54.1% ± 0.25% in the CG but without significant difference (P = 0.206), and vascular tortuosity was significantly present in the NDRG with 32.5% of eyes versus 11.1% of eyes in the CG (P = 0.003).CONCLUSION:OCTA is a promising tool to identify microvascular changes in the diabetic retina before clinically visible retinopathy occurrence. It may identify in the future individuals at risk of developing retinopathy and therefore those needing a better balance of diabetes.

Retinal structural abnormalities in young adults with psychosis spectrum disorders

BackgroundStructural retinal architecture in living organisms became measurable with the development of optical coherence tomography (OCT) scanners. Single-layer analysis with spectral-domain OCT, among other techniques, may provide further insight into pathological changes in complex brain disorders such as psychosis spectrum disorders (PSD). MethodsThis study investigated potential thinning of retinal layers (retinal nerve fiber layer - RNFL, macular volume, macular thickness, ganglion cell-inner plexiform layer- GC-IPL, optic cup volume and cup-to-disk ratio) using a spectral-domain OCT device in 33 non-acute PSD patients (illness duration 5.9 ± 3.9 years) and 35 healthy controls. ResultsIn comparison to age and gender matched controls, patients had bilateral reductions in GC-IPL layer thickness and macular volume. Macular central subfield thinning was found in the right eye, while average macular thickness was lower in the left eye only. RNFL thinning was not observed in patients in comparison to controls, but we noticed that status of this layer could be affected by daily dose of antipsychotics and by illness duration. ConclusionTaken together, our results reveal that retinal thinning is present in young adults with PSDs, but in comparison to the literature we found more prominent changes in both GC-IPL and macular volume/thickness, than in RNFL. Our findings may reflect synaptic loss and neuronal atrophy in non-acute young patients with psychosis.

OCT Biometry (B-OCT): A New Method for Measuring Ocular Axial Dimensions.

Purpose To present a new method of measuring ocular axial dimensions, termed OCT biometry (B-OCT). Design Observational cross-sectional study and evaluation of new diagnostic technology. Methods B-OCT was implemented in the spectral domain OCT device for posterior and anterior segment imaging (REVO NX, Optopol Technology). A total of 349 eyes (214 of healthy subjects, 115 of patients with cataract, and 20 with severe macular diseases) were enrolled in the study. The results of B-OCT were compared to swept source OCT-based IOLMaster 700 (Carl Zeiss Meditec). Differences in measurement values between the two biometers were determined using the paired t-test. Agreement was assessed through intraclass correlation coefficients (ICCs) and Bland–Altman plots. Results B-OCT obtained with REVO NX provides excellent interobserver reproducibility (ICC for: axial length (AXL) = 1.000; central corneal thickness (CCT) = 0.933; anterior chamber depth (ACD) = 0.933; lens thickness (LT) = 0.985) and intraobserver repeatability (ICC for: AXL = 1.000; CCT ≥ 0.994; ACD = 0.998; LT ≥ 0.993). The correlation between measurements made using both devices was outstanding (ICC for: AXL, healthy = 1.000; AXL, cataractous = 1.000; ACD, healthy = 0.998; ACD, cataractous = 0.997; LT, healthy = 0.998; LT, cataractous = 0.997; CCT, healthy = 0.989; CCT, cataractous = 0.979). The mean AXL measurement difference in healthy eyes was −0.001 ± 0.016 mm (the 95% LoA ranged from −0.034 to 0.031); mean ACD difference was 0.000 ± 0.024 mm (95% LoA, −0.047 to 0.047); mean LT difference was −0.002 ± 0.024 mm (95% LoA, −0.050 to 0.046); and mean CCT difference was −0.8 ± 5.1 μm (95% LoA, −10.81 to 9.26). The mean AXL measurement difference in cataractous eyes was −0.003 ± 0.022 mm (95% LoA, −0.046 to 0.039); mean ACD difference was 0.003 ± 0.029 mm (95% LoA, −0.054 to 0.059); mean LT difference was −0.002 ± 0.025 (95% LoA, −0.051 to 0.048); and mean CCT difference was 2.7 ± 6.4 μm (95% LoA, −9.80 to 15.7). Conclusion The study shows small, nonsignificant differences between the biometric measurements obtained with REVO NX B-OCT and IOLMaster 700, which is of high significance for IOL power selection. As B-OCT utilizes a conventional OCT device, the measurements of the ocular axial dimensions are combined with high-resolution macular scans for the simultaneous assessment of central retina as a part of screening for macular pathology. The presented method is the first spectral domain OCT-based biometry technique and the only one integrated into a standard OCT device. Thus, it brings novel functionality to OCT technology.