Depth Imaging Optical Coherence Research Articles

Contemporary status of diagnostic endoluminal ultrasound and optical coherence tomography in the ureter

AbstractObjectiveTo evaluate via a review of published literature, the efficacy of endoluminal ultrasound (ELUS) and optical coherence tomography (OCT) in the following ureteric diseases: urolithiasis, upper tract urothelial carcinoma, stricture disease and pelvic‐ureteric junction obstruction (PUJO).Patients and methodsUreteric high‐frequency ELUS provides 360° imaging, to a depth of 20 mm, and has been demonstrated to assess ureteric stricture length, degree of fibrosis and aetiology. OCT produces high‐quality images with a penetration depth of 2 mm. ELUS has proven to be useful at the time of endopyelotomy for PUJO as it can identify crossing vessels, some not detectable on CT angiography, allowing the urologist to avoid these when making their incision. Ureteric ELUS may be utilised for submucosal ureteric stones as they are highly visible. Endoluminal ultrasound may be deployed in the case of known sub‐mucosal urolithiasis when the ureter appears stone‐free. It may help identify sub‐mucosal stones or stones within diverticulum.ResultsEndoluminal ultrasound has been analysed for its use in determining muscle‐invasive urothelial carcinoma of the ureter. The PPV for ≥pT2 was only 16.7% in one study of six patients with MIBC and 76.2% in 21 patients with <pT2 disease. Analysis of OCT for staging UTUC during ureteroscopy and biopsy demonstrated sensitivity for tumour invasion of 100% and specificity of 92%, 83% of lesion staging matched with histological analysis. Imaging analysis did not match histology in three patients with large exophytic tumours that exceeded the OCT depth penetration. Due to its superficial penetration, OCT cannot reliably stage large tumours.ConclusionsUreteric ELUS has been reported to be a useful tool in endopyelotomy, urolithiasis and stricture disease. The staging of ureteric urothelial carcinoma remains unsatisfactory with current imaging techniques and biopsy methods, and, based on the current literature, ELUS does not appear to have a strong enough PPV to determine muscle invasion. Ureteric OCT may be a useful tool in the future staging of upper tract urothelial carcinoma, particularly in differentiating the stage of small tumours. Further studies are needed in this area.

Choroidal vascular changes in non-alcoholic fatty liver disease.

The most common cause of death in nonalcoholic fatty liver disease (NAFLD) is cardiovascular disease. Choroidal microvascular structure in the eye may be a predictor of systemic vascular disease. We aimed to evaluate the effects of NAFLD on the choroidal microvascular structure using enhanced depth optical coherence tomography (EDI-OCT). This prospective study was conducted by evaluating a total of 96 patients, 52 with steatosis and 44 without steatosis. After anthropometric measurements and ultrasonography were performed in the Gastroenterology Clinic, venous blood samples were taken for biochemical examinations. Then, all patients underwent an eye examination by an ophthalmologist. Subfoveolar choroidal thickness (SFCT) values of the cases were measured with EDI-OCT. Choroid vascular index (CVI) measurements were obtained by dividing the subfoveal choroidal area in the EDI-OCT images into luminal and stromal areas using the image binarization technique (ImageJ). In statistical analysis, the chi-square test was used to compare categorical data, and the independent t-test and Mann-Whitney U test were used to compare quantitative data. The mean age of those with fatty liver was 41±15.7 years, and of those without fatty liver it was 46 ± 10.7 years. There was nostatistically significant difference between the groups in terms of age (p = 0.064). Body mass index (BMI), waist circumference (WC), glucose, uric acid, alanine aminotransferase (ALT), gamma glutamyl transpeptidase (GGT), total cholesterol (TC), ferritin, insulin, and Homestatic Model Assesment - Insuline Restistance (HOMA-IR) were statistically significantly higher in the NAFLD group. On the other hand, there was no statistically significant difference between the groups in terms of low-density lipoprotein (LDL)-cholesterol, high-density lipoprotein (HDL)-cholesterol, triglyceride, and aspartate aminotransferase (AST) values. The mean SFCT was measured as 280.26 ± 23.68 microns in the NAFLD group, and 308.96 ± 18.57 microns in the control group. There was no statistically significant difference in SFCT between the groups (p = 0.077). CVI measurements were 0.63 and 0.65, respectively, and they were significantly lower in the group with NAFLD (p = 0.045). This is the first study in the literature to compare patients with and without ultrasonographic fatty liver in terms of choroidal vascular changes. We found that the choroidal vascular index decreased in NAFLD. This result proves that NAFLD causes changes at the microvascular level and is a multisystemic disease.

Impact of obesity on peripapillary choroidal thickness, macular choroidal thickness, and lamina cribrosa morphology

BackgroundObesity is known to be a significant risk factor for many ocular diseases. In order to understand the mechanism of obesity-related ocular diseases, we examined the lamina cribrosa morphology, peripapillary choroidal thickness (PPCT), and macular choroidal thickness (MCT) in obese women using optical coherence tomography (OCT). MethodsThis comparative cross-sectional study included the right eyes of 72 obese women and 63 healthy women classified based on body mass index (BMI). Each participant underwent a thorough ophthalmological examination and enhanced depth (EDI) OCT imaging, including measurements of PPCT from a total of 12 regions, MCT from a total of 7 regions, Bruch's membrane opening (BMO), lamina cribrosa thickness (LCT), lamina cribrosa depth (LCD), intraocular pressure (IOP), and central corneal thickness (CCT). ResultsThe mean age and BMI of the obese group were 32.36±7.38 years and 35.11±4.39 kg/m², while those of the control group were 31.64±7.78 years and 20.88±1.72 kg/m² (p = 0.658, and p<0.001, respectively). PPCT N1000, PPCT N1500, PPCT S1500, and PPCT T1500 were statistically significantly thinner in the obese group than the control group (p values were 0.039, 0.012, 0.027, and 0.036, respectively). IOP and CCT were significantly higher in the obese group than the control group (p = 0.016, and p = 0.019, respectively). There was no statistically significant difference between the two groups in terms of MCT, BMO, LCT, and LCD. ConclusionWe discovered thinning in the PPCT, which indicates microvascular abnormalities in the optic disc head. Microvascular alteration in the peripapillary region may be a potential initial event in the pathogenesis of several obesity-related ocular diseases, especially glaucoma.

Insights into the underlying choroid in different stages of idiopathic epiretinal membranes after Viteromacular surgery.

The purpose of the study was to longitudinally investigate the correlation between choroidal morphologic and vascular parameters and postoperative visual outcome in different stages of idiopathic epiretinal membranes (iERMs). A prospective, observational, institutional case series of 102 consecutive patients diagnosed with unilateral iERMs were recruited at Peking University Third Hospital and were followed up for 12 months after surgical treatment with vitrectomy. Participants were classified into four stages according to current staging scheme. All eligible subjects underwent standardized imaging evaluation of choroidal parameters including subfoveal choroidal thickness (SFCT), choroidal vascularity index (CVI), and choroidal capillary perfusion (CCP) at baseline and each follow-up by enhanced depth optical coherence tomography (EDI-OCT) and OCT angiography (OCTA). Longitudinal follow-up of choroidal parameters over 12 months was analysed, and their correlations with best-corrected visual acuity (BCVA) were also assessed for predictive prognostic value. CVI and CCP were significantly correlated with BCVA at each follow-up examination (all p < 0.05). However, SFCT exhibited no variation among different stages of iERMs at baseline (p=0.981) or during follow-up (p=0.520). The preoperative CVI correlated with 12-month postoperative BCVA (p < 0.001) and its predictive prognostic effect on BCVA was validated in multiple regression analysis (p=0.006). CVI varied among different stages of iERM and was significantly correlated with visual outcomes after the surgery. CVI could serve as a predictive prognostic marker in iERMs, which further indicates the underlying choroid should be taken into consideration in clinical evaluation of iERMs.

Two-photon interference LiDAR imaging.

Optical Coherence Tomography (OCT) is a key 3D imaging technology that provides micron scale depth resolution for bio-imaging. This resolution substantially surpasses what it typically achieved in Light Detection and Ranging (LiDAR) which is often limited to the millimetre scale due to the impulse response of the detection electronics. However, the lack of coherence in LiDAR scenes, arising from mechanical motion for example, make OCT practically infeasible. Here we present a quantum interference inspired approach to LiDAR which achieves OCT depth resolutions without the need for high levels of stability. We demonstrate depth imaging capabilities with an effective impulse response of 70 μm, thereby allowing ranging and multiple reflections to be discerned with much higher resolution than conventional LiDAR approaches. This enhanced resolution opens up avenues for LiDAR in 3D facial recognition, and small feature detection/tracking as well as enhancing the capabilities of more complex time-of-flight methods such as imaging through obscurants and non-line-of-sight imaging.

Acute and chronic occlusive disorders of the choroidal vasculature (ischemias)

Choroidal ischemia is a less common finding than retinal and optic nerve lesions due to difficulties in its evaluation, which may be caused by systemic diseases and/or local vascular disorders. Indocyanine green angiography is the most valuable imaging method for visualizing the choroidal circulation. Today, the use of optical coherence tomography angiography and enhanced depth optical coherence tomography has significantly improved the understanding of the choroid. In this way, it has been shown that the underlying cause in the pathogenesis of many retinal diseases may be choroidal circulatory disorders. The purpose of this review is to provide an overview of acute and chronic occlusive disorders (ischemias) of the choroidal vasculature.

Case report of benign familial fleck retina

Benign familial fleck Retina is a rare inherited retinal disease first reported by Sabel Aish and Dajani in 1980. It is an autosomal recessive condition associated with a distinctive retinal appearance with no apparent visual or electrophysiological deficits. Fundus photography, autofluorescence and enhanced depth optical coherence tomography B-scan imaging modalities aid in the diagnosis. We present a case report of a 19-year-old female diagnosed with benign familial fleck retina which belongs to a heterogeneous group of flecked retina syndromes, and should be considered in patients with yellowish-white retinal lesions sparing the macula.

An integrated analysis of clinical and morphometric indications of atrophic forms of age-related macular degeneration

The atrophic form of late age-related macular degeneration (AMD) is a common cause of severe vision loss. Recently, a new classification system has been proposed, which identifies two types of atrophy in the late stage of AMD that require a more detailed study: (1) drusenassociated geographic atrophy (GA), which is the final stage of progression of dry AMD, and (2) macular atrophy (MA), which occurs in wet AMD, including the period of AMD treatment with angiogenesis inhibitors. Purpose: an integrated analysis of clinical and morphometric signs of atrophic AMD forms. Material and methods. 48 people (61eyes) aged 48–84 with GA (group 1) and MA (group 2) and a control group, recruited from age-matching 25 healthy volunteers (35 eyes), underwent standard ophthalmological examinations, fundus autofluorescence (FAF) with lesion area measurement, fundus photography, optical coherence tomography (OCT) in the standard mode and Enhanced Depth Imagine Mode, Multicolor, and OCT angiography. Results. The comparative analysis of two atrophic AMD forms showed that in GA eyes, foci of atrophy capturing the fovea were significantly more common, while, contrariwise in MA eyes atrophic foci not capturing the fovea were more frequent (p &lt; 0.05). Photoreceptor tubulation was diagnosed mainly in eyes with GA (p &lt; 0.05). The morphometric analysis showed a significant decrease in the subfoveal thickness of the choroid in the groups with GA and MA as compared to the control (p &lt; 0.05), whilst no significant differences between two groups were noted. The assessment of the frequency of occurrence of types of fundus AF patterns in groups 1 and 2 followed by a comparative analysis, showed the presence of all types of patterns in GA patients, including the heterogeneous and the bordering pattern (p &lt; 0.05). In the MA group, diffuse and focal types of patterns were revealed, while the frequency of the diffuse pattern turned out to be significantly more frequent (p &lt; 0.05). Conclusion. The integrated analysis revealed the main semiological signs and morphometric parameters, their features and prevalence in GA and MA, which may have diagnostic and prognostic importance for the management and treatment of patients with AMD.

Evaluation of choroidal thickness in children with acute asthma attack by optical coherence tomography.

To evaluate the change in central choroidal thickness in children with asthma attack before and after treatment with β2 agonists. About 100 eyes of 50 patients (5-17 years old) with visual acuity of 20/20 who had no retinal, choroidal, and systemic comorbidity were examined by enhanced depth optical coherence tomography (EDI-OCT) before and after asthma attack treatment. Sixty eyes of 30 healthy children of similar age and gender were evaluated as the control group. The central choroidal thickness, peak expiratory flow (PEF), forced expiratory volume 1(FEV1), oxygen saturation, and heart rate were evaluated. The mean age of the patients was 9.2 ± 3.1 years, and the mean saturation values of patients was 97.2 ± 1.3 before treatment, and it increased to 98.3 ± 0.9 after treatment with a statistically significant difference. The mean FEV1 values were 80.8 ± 15.2 before, and 92.7 ± 12.9 after the treatment and PEF values were 75.9 ± 18.6 before and 89.3 ± 18.9 after treatment. This differences were statistically significant (p < 0.001). The average choroidal thickness before the treatment were 310.4 ± 34.2 μm and decreased to 302.7 ± 34.4 μm after the treatment, this decrease was statistically significant (p < 0.001). The mean choroidal thickness of the control group was 303.0 ± 7.3 μm and compared to the pre-treatment and post-treatment values, it was more similar to the post-treatment values, although there was no statistically difference. In our study, it was shown that choroidal thickness was significantly reduced in children with asthma who received attack treatment with β2 agonists, and it was similar to the control group after the treatment.

Long-term follow-up of choroidal changes following COVID-19 infection: analysis of choroidal thickness and choroidal vascularity index

ObjectiveTo investigate subclinical choroidal involvement in patients with systemic coronavirus disease 2019 (COVID-19) infection and evaluate its long-term course. Materials and MethodsThis prospective, longitudinal study included 32 eyes of 16 COVID-19 patients and 34 eyes of 17 age-matched healthy control subjects. All the participants had a detailed ophthalmologic assessment, including visual acuity assessment, slit-lamp examination, and indirect ophthalmoscopy. Enhanced depth optical coherence tomography imaging of the posterior pole and peripapillary region was performed in the early (days 15–40) and late (ninth month) postinfectious periods. Choroidal vascularity index (CVI) was calculated using ImageJ software (National Institutes of Health, Bethesda, Md.). ResultsNone of the patients had any examination finding associated with the ocular involvement of COVID-19. Subfoveal choroidal thickness (SFCT) decreased significantly in the early postinfectious period compared with the healthy control individuals (p = 0.045). SFCT increased significantly in the late postinfectious period compared with the early period (p = 0.002), and the difference between patients and control individuals became statistically insignificant (p = 0.362). There was a similar trend for the peripapillary choroidal thickness measurements. CVI remained unchanged (p = 0.721) despite the significant decrease in SFCT and total choroidal area (p = 0.042), indicating that this decrease occurred both in choroidal stroma and in blood vessels. CVI remained unchanged in the late postinfectious period (p = 0.575) compared with the early period, indicating that recovery occurred in the entire choroidal tissue. ConclusionThis study demonstrates that choroidal thickness was reduced in all measured areas and that this decrease affected all choroidal layers. This choroidopathy was reversible and recovered in the ninth postinfectious month.

Navigated, Robot-Driven Laser Craniotomy for SEEG Application Using Optical Coherence Tomography in an Animal Model.

Objectives: We recently introduced a navigated, robot-driven laser beam craniotomy for use with stereoelectroencephalography (SEEG) applications. This method was intended to substitute the hand-held electric power drill in an ex vivo study. The purpose of this in vivo non-recovery pilot study was to acquire data for the depth control unit of this laser device, to test the feasibility of cutting bone channels, and to assess dura perforation and possible cortex damage related to cold ablation. Methods: Multiple holes suitable for SEEG bone channels were planned for the superior portion of two pig craniums using surgical planning software and a frameless, navigated technique. The trajectories were planned to avoid cortical blood vessels using magnetic resonance angiography. Each trajectory was converted into a series of circular paths to cut bone channels. The cutting strategy for each hole involved two modes: a remaining bone thickness mode and a cut through mode (CTR). The remaining bone thickness mode is an automatic coarse approach where the cutting depth is measured in real time using optical coherence tomography (OCT). In this mode, a pre-set measurement, in mm, of the remaining bone is left over by automatically comparing the bone thickness from computed tomography with the OCT depth. In the CTR mode, the cut through at lower cutting energies is managed by observing the cutting site with real-time video. Results: Both anesthesia protocols did not show any irregularities. In total, 19 bone channels were cut in both specimens. All channels were executed according to the planned cutting strategy using the frameless navigation of the robot-driven laser device. The dura showed minor damage after one laser beam and severe damage after two and three laser beams. The cortex was not damaged. As soon as the cut through was obtained, we observed that moderate cerebrospinal fluid leakage impeded the cutting efficiency and interfered with the visualization for depth control. The coaxial camera showed a live video feed in which cut through of the bone could be identified in 84%. Conclusion: Inflowing cerebrospinal fluid disturbed OCT signals, and, therefore, the current CTR method could not be reliably applied. Video imaging is a candidate for observing a successful cut through. OCT and video imaging may be used for depth control to implement an updated SEEG bone channel cutting strategy in the future.

Classification of Non-Infectious and/or Immune Mediated Choroiditis: A Brief Overview of the Essentials.

The choroid was poorly accessible to imaging investigation until the last decade of the last century. With the availability of more precise imaging methods such as indocyanine green angiography (ICGA) and, later, optical coherence tomography (OCT), enhanced depth OCT (EDI-OCT), and OCT angiography (OCTA), appraisal of choroidal inflammation has substantially gained in accuracy. This allowed to precisely determine which structures were touched in the different non-infectious choroiditis entities and made it possible to classify this group of diseases, ICGA signs, mainly hypofluorescent lesions, were identified and described. Previous publications have divided angiographic findings into two main sets of signs: (1) irregular “geographic” hypofluorescent areas corresponding to choriocapillaris non-perfusion and (2) round more regular, hypofluorescent dark dots more evenly distributed in the fundus corresponding to more deep choroidal stromal foci. These distinct findings allowed to subdivide and classify choroiditis into choriocapillaritis and stromal choroiditis. Additional signs were identified from EDI-OCT and OCTA examination supporting the classification of choroiditis into choriocapillaritis and stromal choroiditis. Results: Diseases involving principally the choriocapillaris included Multiple Evanescent White Dot Syndrome (MEWDS), Acute Posterior Multifocal Placoid Pigment Epitheliopathy (APMPPE), Idiopathic Multifocal Choroiditis (MFC), and Serpiginous Choroiditis (SC) as well as mixed forms. Diseases primarily involving the choroidal stroma included HLA-A29 Birdshot Retinochoroiditis (BRC), Vogt-Koyanagi-Harada disease (VKH), Sympathetic Ophthalmia (SO), and Sarcoidosis chorioretinitis (SARC). Thanks to new imaging investigations of the choroid, it is now possible to classify and understand the diverse clinicopathological mechanisms in the group of non-infectious choroiditis entities.

Indentation probe with optical fibre array‐based optical coherence tomography for material deformation

We present a new optomechanical probe for mechanical testing of soft matter. The probe consists of a micromachined cantilever equipped with an indenting sphere, and an array of 16 single‐mode optical fibres, which are connected to an optical coherence tomography (OCT) system that allows subsurface analysis of the sample during the indentation stroke. To test our device and its capability, we performed indentation on a PDMS‐based phantom. Our findings demonstrate that Common Path (CP)‐OCT via lensed optical fibres can be successfully combined with a microindentation sensor to visualise the phantom's deformation profile at different indentation depths and locations in real time.Lay DescriptionThis work presents a new approach to simultaneously perform micro‐indentation experiments and OCT imaging. An optical fiber array‐based sensor is used to develop a new hybrid tool where micro‐indentation is combined with optical coherence tomography. The sensor is therefore capable of compressing a sample with a small force and simultaneously collecting OCT depth profiles underneath and around the indentation point. This method offers the opportunity to characterize the mechanical properties of soft materials and simultaneously visualize their deformation profile. The ability to integrate OCT imaging with indentation technology is promising for the non‐invasive and precise characterization of different soft materials.

Comparison of choroidal thickness before and after injection of ranibizumab in patients with diabetic macular edema

ObjectiveTo compare choroidal thickness before and after injection of ranibizumab in patients with diabetic macular edema (DME) using enhanced depth optical coherence tomography (EDI-OCT).BackgroundDME is one of the most common complications of diabetic retinopathy (DR) and the most common cause of visual impairment. Intravitreal injection of antivascular endothelial growth factor is currently the most commonly used procedure for the treatment of DME.Patients and methodsA prospective clinical study was conducted on 30 eyes of 27 patients of DME who underwent intravitreal injection of ranibizumab. A complete history was taken from all cases, and a full ophthalmologic examination was done. Fluorescein angiography and EDI-OCT were performed before injection and also at 1 month after injection. The difference between preoperative and postoperative subfoveal choroidal thickness was calculated.ResultThe mean preoperative choroidal thickness measured subfoveally using EDI-OCT was 233.1 ± 20.22, whereas the mean of postoperative choroidal thickness after 1 month was 214.4 ± 19.61. The range of difference between preoperative and 1 month postoperative choroidal thickness using EDI-OCT was from 23 to 28 μm and the mean was 18.67 ± 8.99; the difference was calculated by subtracting the preoperative choroidal thickness from 1-month postoperative choroidal thickness.ConclusionThere is a significant difference between the preoperative and 1-month postoperative choroidal thickness using EDI-OCT after injection of intravitreal ranibizumab in DME.

Measurement of Diurnal Variation in Rod Outer Segment Length In Vivo in Mice With the OCT Optoretinogram.

PurposeTo investigate diurnal variation in the length of mouse rod outer segments in vivo.MethodsThe lengths of rod inner and outer segments (RIS, ROS) of dark-adapted albino mice maintained on a 12-hour dark:12-hour light cycle with light onset 7 AM were measured at prescribed times (6:30 AM, 11 AM, 3:30 PM) during the diurnal cycle with optical coherence tomography (OCT), taking advantage of increased visibility, after a brief bleaching exposure, of the bands corresponding to RIS/ROS boundaries and ROS tips (ROST).ResultsDeconvolution of OCT depth profiles resolved two backscatter bands located 7.4 ± 0.1 and 10.8 ± 0.2 µm (mean ± SEM) proximal to Bruch's membrane (BrM). These bands were identified with histology as arising from the apical surface of RPE and ROST, respectively. The average length of dark-adapted ROS at 6:30 AM was 17.7 ± 0.8 µm. By 11 AM, the average ROS length had decreased by 10% to 15.9 ± 0.7 µm. After 11 AM, the ROS length increased steadily at an average rate of 0.12 µm/h, returning to baseline length by 23.5 hours in the cycle.ConclusionsThe diurnal variation in ROS length measured in these experiments is consistent with prior histological investigations showing that rodent rod discs are phagocytosed by the RPE maximally over several hours around the time of normal light onset. The rate of recovery of ROS to baseline length before normal light onset is consistent with the hypothesis that disc membrane synthesis is fairly constant over the diurnal cycle.

Impact of Carotid Endarterectomy on Choroidal Thickness and Volume in Enhanced Depth Optical Coherence Tomography Imaging.

Purpose Carotid endarterectomy (CEA) is considered an effective therapeutic method for improving ocular circulation. The choroid is a predominantly vascular tissue; thus, systemic and local vascular alterations may influence its morphology and function. The aim of the current study was to analyse changes in choroidal thickness and volume in patients with significant internal carotid artery stenosis (ICAS) before and after unilateral CEA. Methods The 42 eyes of the 21 asymptomatic patients included in the study were divided into two groups: those ipsilateral (EIE) and those contralateral (ECE) to CEA. All participants underwent a complete ophthalmologic examination, including enhanced depth imaging-optical coherence tomography (EDI-OCT). A comparative analysis of subfoveal thickness (CT) and choroidal volume (CV) measured in nine Early Treatment of Diabetic Retinopathy Study (ETDRS) subfields at baseline, on the 2nd day after CEA, and in the 3rd month after CEA was performed. Results In the EIE and ECE groups, no significant differences in either CT or CV values before and on the 2nd day after the CEA were observed. In the EIE group, a significant increase in CT and CV in the 3rd month after CEA compared to baseline was noted in the specific ETDRS region. Changes in CT and CV after surgery were positively correlated with the participants' physical activity status and diastolic blood pressure and negatively correlated with the participants' age and smoking status. Additionally, the analysis of changes in CV after CEA showed a positive correlation between the EIE and ECE groups. Conclusions CT and CV fluctuations in the central and perifoveal areas visualized with EDI-OCT enabled the observation of the processes of tissue adaptation to variable blood flow conditions.

Investigation of sputtering target re-deposits by Optical Coherence Tomography and grazing incident X-ray diffraction

The sputtering target re-deposit grown by cumulative sputtering has been investigated in this work by studying both fresh and rigorously sputtered zirconium oxide target by Fourier Domain Optical Coherence Tomography (FDOCT), a depth resolved optical imaging modality. The Optical Coherence Tomography (OCT) depth profiles have further been analysed to extract optical attenuation coefficient of sputtered target surface as well as fresh target surface. Re-deposited sputtered target surface shows larger optical attenuation coefficient in the range of 1.5–4.4 mm−1 as opposed to that of 1.1 mm−1 for fresh ZrO2 target. The same sputtered target surfaces have also been looked into by using grazing incident X-ray diffraction technique with an optimised grazing angle of incidence. A strong correlation between structural changes of re-deposited surface and the extent of light depth penetration obtained by analysing OCT depth profiles at different locations of the sputtered target was observed. The results indicate, that FDOCT can be considered to be an effective tool to probe sputtering target re-deposits, with the advantage of being faster and non-contact method.

Optimized imaging of the suprachoroidal space with swept-source OCT

Purpose: To compare enhanced depth imaging (EDI) and non-EDI swept source optical coherence tomography (SS-OCT) in their ability to capture the suprachoroidal space (SCS).&#x0D; Materials and methods: Twenty volunteers with a minimum age of 18 years without any ocular pathology and refractive error below Å} 2 diopters underwent SS-OCT foveal scanning, with and without EDI. Masked averaged B-scan lines were analyzed for presence of the SCS. When the SCS was seen, the percentage of the scan on which this structure could be unequivocally observed was measured. Scores obtained from the images taken with or without EDI were then compared.&#x0D; Results: Thirty-seven eyes were analysed, since three eyes of three different patients were eliminated, as the outer border of the choroid was insufficiently delineated with both modalities. The SCS was not detected at all on 14 pictures (37.8%) obtained by non-EDI SS-OCT and 9 pictures (24.3%) obtained by EDI SS-OCT. When the SCS was detected with both modalities, it was observable on 27.2+/-24.2% of the scan without EDI and 40.4+/-30.3 of the scan with EDI (p &lt; .001)&#x0D; Conclusions: EDI SS-OCT enables a more frequent and extensive visualization of the suprachoroidal space than non-EDI SS-OCT. This new approach could be considered as the most accurate modality to currently visualize the SCS in vivo.

Presurgical evaluation of basal cell carcinoma using combined reflectance confocal microscopy–optical coherence tomography: A prospective study

Initial biopsy of basal cell carcinoma (BCC) may fail to show aggressive histologic subtypes. Additionality, the clinical evaluation of BCC before surgery can miss subclinical extension. Reflectance confocal microscopy (RCM) and optical coherence tomography (OCT) are emerging tools that can help in the presurgical evaluation of BCCs. To assess the feasibility of a combined RCM-OCT imaging modality for presurgical evaluation of biopsy-proven BCCs for residual tumor, margin status, and depth. Thirty-eight BCCs in 35 patients referred to a tertiary cancer center for Mohs micrographic surgery (MMS) were imaged with combined RCM-OCT. Images were correlated to MMS frozen sections. Thirty-eight BCCs were analyzed. The mean age of patients was 67.34 years (range, 36-84 years), and 20 patients were female (57.14%). Twenty four BCCs were located on the head (63.16%) , and the mean size was 8.58 mm (range, 3-30 mm). RCM-OCT showed an overall agreement of 91.1% with MMS frozen sections. A sensitivity of 82.6% (95% confidence interval [CI], 69%-92%), specificity of 93.8% (95% CI, 88%-97%), and receiver operating characteristic curve of 0.88 (95% CI, 0.82-0.94) was found. OCT depth was highly correlated with MMS depth (r2 = 0.9). Small sample size and difficulty evaluating certain challenging anatomic sites. Combined RCM-OCT may emerge as a useful tool for presurgical evaluation of BCCs.

Enhanced depth imaging and swept-source optical coherence tomography findings in choroidal osteoma: a case report

The aim of this study was to report the findings from enhanced depth imaging (EDI) and swept-source optical coherence tomography (OCT) in a choroidal osteoma. A case study of a patient with choroidal osteoma is presented and discussed. A 25-year-old woman presented with an asymptomatic peripapillary mass. Fundus examination revealed a yellow–orange, well-defined geographical lesion. B‑scan ultrasonography, corroborated by fundus autofluorescence (FAF) and OCT findings, pointed to the diagnosis of choroidal osteoma. Calcified areas of the tumor were iso-autofluorescent on FAF and hyporeflective on OCT, revealing the morphological patterns of cancellous bone, including a sponge-like pattern and lines indicating lamellae, Haversian canals, and cement lines. Decalcified patches of the tumor were hypofluorescent on FAF and hyperreflective on OCT and showed overlying retinal damage—most prominently depigmentation and retinal pigment epithelium disruptions. A central area of the tumor revealed unusual characteristics; hyperreflectivity on OCT indicating decalcification but isofluorescence on FAF and sharing the same color as the rest of the retina on fundus photography. The area also differed from the other decalcified areas with its cumulus cloud-like appearance. Compared with EDI-OCT, SS-OCT images showed some increased definition of the bony features of the tumor, especially in its deeper layers, as well as a mild reduction of the shadowing caused by overlying retinal vessels. The morphological features of a choroidal osteoma are demonstrated using EDI- and SS-OCT. Calcified and decalcified areas of the tumor were differentiated, as well as another area showing unexpected characteristics. In our case, SS-OCT imaging revealed very similar features to EDI-OCT.