Development Of Optical Coherence Tomography Research Articles

Deep attention for enhanced OCT image analysis in clinical retinal diagnosis

AbstractRetinal illnesses such as age-related macular degeneration (AMD) and diabetic maculopathy pose serious risks to vision in the developed world. The diagnosis and assessment of these disorders have undergone revolutionary change with the development of optical coherence tomography (OCT). This study proposes a novel method for improving clinical precision in retinal disease diagnosis by utilizing the strength of Attention-Based DenseNet, a deep learning architecture with attention processes. For model building and evaluation, a dataset of 84495 high-resolution OCT images divided into NORMAL, CNV, DME, and DRUSEN classes was used. Data augmentation techniques were employed to enhance the model's robustness. The Attention-Based DenseNet model achieved a validation accuracy of 0.9167 with a batch size of 32 and 50 training epochs. This discovery presents a promising route for more precise and speedy identification of retinal illnesses, ultimately enhancing patient care and outcomes in clinical settings by integrating cutting-edge technology with powerful neural network architectures.

Development of optical coherence tomography incorporated image processing algorithms for the multidimensional assessment of concealed enamel micro-crack

Enamel microcracks (EMCs) are tiny fractures that occur in the outer layer of teeth, allowing some extrinsic stains and leading to an unaesthetic tooth. Additionally, the EMCs enhance the accumulation of plaque and thus EMCs could be highly suspectable zones for caries development. Therefore, the assessment of EMCs is crucial for early diagnosis and to prevent unwanted damage to teeth. In this study, a concealed EMCs detection and length-measuring algorithm, and an EMCs width-measuring algorithm were applied for optical coherence tomography (OCT) image analysis to assess the EMCs progression in both length and width. Additionally, a surface noise-removing algorithm was developed to obtain a better visualization of OCT cross-sectional and volumetric images. The developed algorithms were successfully used to detect concealed EMCs and track their progression in both length and width directions before and after the orthodontic treatment. Obtained results revealed a micro-scale progression of EMCs in both length and width directions after the orthodontic treatment, where the averaged progression of EMCs in length and width were 712.5 and 92.75 µm, respectively. Therefore, high-resolution, non-invasive OCT imaging with developed image processing algorithms can be a fruitful solution to use as a diagnostic tool to monitor the precise coordinates of concealed EMCs throughout the orthodontic treatment.

Seeing is believing: The development of optical coherence tomography

The 2023 Lasker-DeBakey Clinical Medical Research Award is being presented to James Fujimoto, David Huang, and Eric Swanson for their invention and development of optical coherence tomography (OCT), an imaging technology that uses light to visualize microscopic structures within tissues such as the retina. OCT has dramatically changed the practice of ophthalmology and improved the lives of millions of people. It also has great potential in a wide range of other medical fields.

Optical coherence tomography split-spectrum amplitude-decorrelation optoretinography.

This pilot study reports the development of optical coherence tomography (OCT) split-spectrum amplitude-decorrelation optoretinography (SSADOR) that measures spatially resolved photoreceptor response to light stimuli. Using spectrally multiplexed narrowband OCT, SSADOR improves sensitivity to microscopic changes without the need for cellular resolution or optical phase detection. Therefore, a large field of view (up to 3 × 1 mm2 demonstrated) using conventional OCT instrument design can be achieved, paving the way for clinical translation. SSADOR promises a fast, objective, and quantifiable functional biomarker for photoreceptor damage in the macula.

Edi Mod Spectral Domain Optical Coherence Tomography Evaluation of The Choroid in Retinitis Pigmentosa: A Case-Control Study

Objective: The evaluation of choroidal thickness measurements became possible after the developments in optical coherence tomography (OCT) technology. This study aimed to evaluate choroidal features in Retinitis Pigmentosa subjects with EDI (Enhanced depth imaging) mode spectral domain optical coherence tomography (SD-OCT). Material and Method: A hundred and three eyes of 54 RP subjects underwent scanning with EDI-OCT for central retinal and choroidal thickness measurements and were compared with 40 healthy controls. Submacular choroidal thickness measurements were obtained beneath the fovea and at 500 µm intervals for 2.5 mm nasal and temporal to the center of the fovea. Results: Mean subfoveal choroidal thickness measurements were 253.2±74.9 µm in RP patients and 336.2±91.7 µm in control (p<0.0001). There was no correlation between subfoveal choroidal thickness and visual acuity in RP patients. The choroid had an irregular shape in 85 % of RP patients. The thickest point of the choroid was not subfoveal as in healthy eyes, and excessive nasal thinning of the choroid was observed in 93 % of RP patients. Conclusion: Submacular choroidal thickness was significantly reduced but did not correlate with the visual acuity in RP patients.

Optical Coherence Tomography Retinal Nerve Fibre Layer and Ganglion Cell Complex Measurements in Normal Southern Nigerian Eyes.

Introduction Glaucoma is the leading cause of irreversible blindness worldwide. It is more severe in people with African heritage, and intraocular pressure remains the only modifiable risk factor in managing glaucoma. Attempts to improve the diagnosis and monitoring of glaucoma are ongoing. One of those attempts is the development of optical coherence tomography (OCT). However, there is a theoretical possibility of a delayed or wrong diagnosis of glaucoma using the OCT because of racial, age, and sex differences in the RNFL (retina nerve fibre layer), GCL (ganglion cell layer), and GCL+IPL (ganglion cell layer and inner plexiform layer) thickness. Objective This study aims to provide the measurements of RNFL, GCL, and GCL+IPL in normal eyes of southern Nigerian patients and specifically to evaluate the relationship of these measurements to gender, age, intra-eye variability, and the Topcon SD-OCT normative database. Method Three hundred and four eyes of 152 patients who had normal OCT scans using the 6x6 RNFL (four sectors) and Macula scans of the Topcon OCT-1 3D Maestro OCT machine were included for analysis. Parametric tests were used to interrogate the relationship between normally distributed parameters and gender, age, and the Topcon reference database. Non-parametric tests were used for non-normally distributed data. Results The male-to-female ratio was 1:1, and ages ranged between 18 and 71 for both genders. The average RNFL values were 111.49 ± 10.44 (right eye - RE) and 111.96 ± 9.66 (left eye - LE). For the GCL, average values were 66.23 ± 4.4 (RE) and 66.34 ± 4.19 (LE). GCL+IPL values were 104.02 ± 6.71 (RE) and 103.89 ± 6.66 (LE). There was no difference between genders (X2 = 56.467; df = 46; p = 0.160), and RNFL, GCL, and GCL+IPL values showed a significant reduction as the age of the respondents increased. There was a significant difference between RNFL, GCL, and GCL+IPL values and the Topcon reference database, p < 0.001. Conclusion Significant differences exist between the Southern Nigerian eyes' RNFL, GCL, and GCL+ IPL values and the Topcon OCT-1 3D Maestro reference database. While randomised control trials and extensive multi-centre studies have not been conducted to determine the possible effects of these differences between measured values and reference databases of the OCTs, they need to be considered while diagnosing and managing glaucoma with the OCT.

OCT-guided Robotic Subretinal Needle Injections: A Deep Learning-Based Registration Approach.

Subretinal injection (SI) is an ophthalmic surgical procedure that allows for the direct injection of therapeutic substances into the subretinal space to treat vitreoretinal disorders. Although this treatment has grown in popularity, various factors contribute to its difficulty. These include the retina's fragile, nonregenerative tissue, as well as hand tremor and poor visual depth perception. In this context, the usage of robotic devices may reduce hand tremors and facilitate gradual and controlled SI. For the robot to successfully move to the target area, it needs to understand the spatial relationship between the attached needle and the tissue. The development of optical coherence tomography (OCT) imaging has resulted in a substantial advancement in visualizing retinal structures at micron resolution. This paper introduces a novel foundation for an OCT-guided robotic steering framework that enables a surgeon to plan and select targets within the OCT volume. At the same time, the robot automatically executes the trajectories necessary to achieve the selected targets. Our contribution consists of a novel combination of existing methods, creating an intraoperative OCT-Robot registration pipeline. We combined straightforward affine transformation computations with robot kinematics and a deep neural network-determined tool-tip location in OCT. We evaluate our framework's capability in a cadaveric pig eye open-sky procedure and using an aluminum target board. Targeting the subretinal space of the pig eye produced encouraging results with a mean Euclidean error of 23.8μm.

A review of deep learning in structure and function in glaucoma

The relationship between structural damage and functional loss in glaucoma is of great importance for its diagnosis and management. The functional status is usually assessed through visual field examination, a subjective test that is burdensome and time-consuming. Moreover, it depends on patients’ answers and there is a learning curve until accurate and reliable measurements are possible. Structural assessment, on the other hand, has remarkably improved since the development of optical coherence tomography, a fast test that allows for objective and quantitative analysis of retinal layers. The relationship between the two tests, however, is complex and nonlinear, and is influenced by interindividual variability. Thus, qualitative evaluation or the use of conventional statistics might not be appropriate. In recent years, we have seen a remarkable evolution of artificial intelligence algorithms and deep learning models. These techniques have proved adequate to model such complicated relationships. In this review, we summarize studies that investigate the structure and function relationship in glaucoma making use of artificial intelligence and deep learning, the challenges associated with predicting visual field information from structural measurements, and the strategies adopted to improve their accuracy.

Factors Associated with Changes in Peripapillary Retinal Nerve Fibre Layer Thickness in Healthy Myopic Eyes.

Myopic people face an elevated risk of primary open angle glaucoma. Changes in the fundus in people with high myopia often lead to misdiagnosis of glaucoma, as this condition has many clinical signs in common with myopia, making the diagnosis of glaucoma more challenging. Compared to reduction of the visual field, a decrease in retinal nerve fibre layer (RNFL) thickness occurs earlier in glaucoma, which is widely considered useful for distinguishing between these conditions. With the development of optical coherence tomography (OCT), RNFL thickness can be measured with good reproducibility. According to previous studies, this variable is not only affected by axial length but also related to the patient's age, gender, ethnicity, optic disc area, and retinal blood flow in myopia. Herein, we intend to summarize the factors relevant to the RNFL in myopia to reduce the false-positive rate of glaucoma diagnosis and facilitate early prevention of myopia.

Optical coherence tomography-angiography as a non-invasive method of pathology diagnosis of the microcirculatory bed of the optic nerve and macula

The review discusses the development of optical coherence tomography with the function of angiography, focusing on its advantages, features, and prospects for the diagnosis of fundus pathologies.

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.

Optical Coherence Tomography Imaging of the Lamina Cribrosa: Structural Biomarkers in Nonglaucomatous Diseases.

The lamina cribrosa (LC) is an active structure that responds to the strain by changing its morphology. Abnormal changes in LC morphology are usually associated with, and indicative of, certain pathologies such as glaucoma, intraocular hypertension, and myopia. Recent developments in optical coherence tomography (OCT) have enabled detailed in vivo studies about the architectural characteristics of the LC. Structural characteristics of the LC have been widely explored in glaucoma management. However, information about which LC biomarkers could be useful for the diagnosis, and follow-up, of other diseases besides glaucoma is scarce. Hence, this literature review aims to summarize the role of the LC in nonophthalmic and ophthalmic diseases other than glaucoma. PubMed was used to perform a systematic review on the LC features that can be extracted from OCT images. All imaging features are presented and discussed in terms of their importance and applicability in clinical practice. A total of 56 studies were included in this review. Overall, LC depth (LCD) and thickness (LCT) have been the most studied features, appearing in 75% and 45% of the included studies, respectively. These biomarkers were followed by the prelaminar tissue thickness (21%), LC curvature index (5.4%), LC global shape index (3.6%), LC defects (3.6%), and LC strains/deformations (1.8%). Overall, the disease groups showed a thinner LC (smaller LCT) and a deeper ONH cup (larger LCD), with some exceptions. A large variability between approaches used to compute LC biomarkers has been observed, highlighting the importance of having automated and standardized methodologies in LC analysis. Moreover, further studies are needed to identify the pathologies where LC features have a diagnostic and/or prognostic value.

Changes in retinal microvasculature and retinal layer thickness in association with apolipoprotein E genotype in Alzheimer\u2019s disease

Biomarker tests of Alzheimer’s disease (AD) are invasive and expensive. Recent developments in optical coherence tomography (OCT) and OCT angiography (OCTA) have enabled noninvasive, cost-effective characterization of retinal layer vasculature and thickness. Using OCTA and OCT, we characterized retinal microvascular changes in the mild cognitive impairment (MCI) stage of AD and assessed their correlation with structural changes in each retinal neuronal layer. We also evaluated the effect of the APOE-ε4 genotype on retinal microvasculature and layer thickness. Retinal layer thickness did not differ between MCI patients (40 eyes) and controls (37 eyes, all p > 0.05). MCI patients had lower vessel density (VD) (p = 0.003) of the superficial capillary plexus (SCP) and larger foveal avascular zone area (p = 0.01) of the deep capillary plexus (DCP) than those of controls. VD of the SCP correlated with the ganglion cell layer (r = 0.358, p = 0.03) and inner plexiform layer thickness (r = 0.437, p = 0.007) in MCI patients. APOE-ε4-carrying MCI patients had a lower VD of the DCP than non-carriers (p = 0.03). In conclusion, retinal microvasculature was reduced in patients with AD-associated MCI, but retinal thickness was not changed; these changes might be affected by the APOE genotype. OCTA of the retinal microvasculature may be useful to detect vascular changes in AD.

Depth-resolved variations in visibility of retinal nerve fibre bundles across the retina in enface OCT images of healthy eyes.

Recent developments in optical coherence tomography (OCT) technology enable direct enface visualisation of retinal nerve fibre bundle (RNFB) loss in glaucoma. However, the optimum depth at which to visualise RNFBs across the retina is unknown. We aimed to evaluate the range of depths and optimum depth at which RNFBs can be visualised across the retina in healthy eyes. The central±25° retina of 10 healthy eyes from 10 people aged 57-75years (median 68.5years) were imaged with spectral domain OCT. Slab images of maximum axial resolution (4μm) containing depth-resolved attenuation coefficients were extracted from 0 to 193.5μm below the inner limiting membrane (ILM). Bundle visibility within 10 regions of a superimposed grid was assessed subjectively by trained optometrists (n=8), according to written instructions. Anterior and posterior limits of RNFB visibility and depth of best visibility were identified for each grid sector. Effects of retinal location and individual eye on RNFB visibility were explored using linear mixed modelling with likelihood ratio tests. Intraclass correlation coefficient (ICC) was used to measure overall agreement and repeatability of grading. Spearman's correlation was used to measure correlation between depth range of visible RNFBs and retinal nerve fibre layer thickness (RNFLT). Retinal location and individual eye affected anterior limit of visibility (χ2(9) =58.6 and 60.5, both p<0.0001), but none of the differences exceeded instrument resolution, making anterior limit consistent across the retina and different eyes. Greater differences were observed in the posterior limit of visibility across retinal areas (χ2(9) =1671.1, p<0.0001) and different eyes (χ2(9) =88.7, p<0.0001). Optimal depth for visualisation of RNFBs was around 20µm below the ILM in most regions. It varied slightly with retinal location (χ2(9) =58.8, p<0.0001), but it was not affected by individual eye (χ2(9) =10.7, p=0.29). RNFB visibility showed good agreement between graders (ICC 0.89, 95%CI 0.87-0.91), and excellent repeatability (ICC 0.96-0.99). Depth range of visible RNFBs was highly correlated with RNFLT (ρ=0.9, 95%CI: 0.86-0.95). The range of depths with visible RNFBs varies markedly across the healthy retina, consistently with RNFLT. To extract all RNFB information consistently across the retina, slab properties should account for differences across retinal locations and between individual eyes.

OCT round-up: Scanning the market

Emma White highlights the latest developments in optical coherence tomography (OCT) technology, for the early detection and monitoring of major eye conditions, from faster scan times and enhanced fundus imaging to remote operation for safe social distancing

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.

Development of optical coherence tomography (OCT) imaging

Development of optical coherence tomography (OCT) imaging

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.

Updates in imaging in ocular oncology.

Innovations in ophthalmic imaging have made a profound impact on the diagnosis and treatment of ophthalmic disease. In ocular oncology, the development of optical coherence tomography with enhanced depth imaging and swept source technologies has made it possible to visualize the anatomical characteristics of retinoblastoma and uveal melanoma with a level of detail previously unobtainable on clinical exam alone. As a result, our understanding of the pathophysiology of vision loss in choroidal melanoma in particular has improved. These modalities have also helped identify fundoscopically “invisible” tumors and risk stratify pre-malignant choroidal lesions, making a strong case for their inclusion in all screening evaluations. Optical coherence tomography angiography, on the other hand, has allowed non-invasive imaging of the retinal and uveal vasculatures, providing insight into vascular changes associated with malignant transformation and vision loss following exposure to radiation. While the impact of new imaging technologies on clinical outcomes and overall survival in ocular oncology has yet to be determined, several reports cited herein offer promising results.

Idiopathic Macular Hole: A Comprehensive Review of Its Pathogenesis and of Advanced Studies on Metamorphopsia.

Vitreous anteroposterior traction is an important factor that affects macular hole (MH) formation at the early stage, and vitreous tangential traction can lead to further hole expansion after hole formation. Recent studies have highlighted the significance of Müller cells for the pathogenesis of MH. Since the advent of MH treatment, success rates for MH closure have significantly improved, as has postoperative visual acuity. However, metamorphopsia, an initial and common symptom of MH, still exists. Metamorphopsia is significantly related to the deterioration of visual quality of life and can be used as an independent index to evaluate visual function before and after surgery. In MH patients, metamorphopsia has different manifestations representing different clinical implications. M-CHARTS, as a new means of inspection, can quantify the degrees of metamorphopsia, and with the development of optical coherence tomography (OCT), layer-by-layer scanning of the retinal structure has become possible. These methods enable detailed analysis of the connections between the degree of metamorphopsia and relevant OCT parameters. Preoperative OCT parameters can be used to evaluate the prognosis of the postoperative visual function of MH patients and are therefore of great significance in guiding the treatment of MH patients.