Hyperreflective Layer Research Articles

Evaluation of a novel forward-looking optical coherence tomography probe for endoscopic applications: an ex vivo feasibility study.

As a result of recent advances in the development of small microelectromechanical system mirrors, a novel forward-looking optical coherence tomography (OCT) probe with a uniquely large field of view is being commercially developed. The aim of this study is to prospectively assess the feasibility of this advanced OCT probe in interpreting ex vivo images of colorectal polyp tissue and to identify necessary steps for further development. A total of 13 colorectal lesions from 9 patients, removed during endoscopic resection, were imaged ex vivo with the OCT device and compared with histopathological images that served as the gold standard for diagnostics. Normal tissue from one patient, removed during the endoscopic procedure, was imaged as a negative control. We assessed the presence of features indicative for polyp type and degree of dysplasia, by comparing OCT images to histopathological images and by evaluating the presence of OCT-specific features identified by previous studies, such as effacement (loss of layered tissue structure), a hyperreflective epithelial layer, and irregularity of the surface. As verified by corresponding histological images, tissue structures such as blood vessels and tissue layers could be distinguished in OCT images of the normal tissue sample. Detailed structures on histological images such as crypts and cell nuclei could not be identified in the OCT images. However, we did identify OCT features specific for colorectal lesions, such as effacement and a hyperreflective epithelial layer. In general, the imaging depth was about 1mm. Some relevant tissue structures could be observed in OCT images of the novel device. However, some adaptations, such as increasing imaging depth using a laser with a longer central wavelength, are required to improve its clinical value for the imaging of colorectal lesions.

Sunrays epiretinal membrane

Aim: To report a unique aspect of an opalescent, symmetrical, sun rays like epiretinal membrane (ERM), assessed with swept source optical coherence tomography (SS‐OCT).Methods: Patient was assessed with multimodal imaging: colour photography and SS‐OCT with B‐scan and en face imaging.Results: A 65‐year‐old male with hypertension and diabetes history, followed in our consultation for pre‐proliferative diabetic retinopathy (DR), lost of sight for two years, presented with progressive visual decrease in his left eye (LE). Best corrected visual acuity (BCVA) of the right eye was 8/10 without any sign of DR activity on fundus examination. BCVA of the LE was limited to hand motion. Anterior segment examination was unremarkable. Fundus examination highlighted the presence of opaque dense ERM lining the posterior pole mimicking a symmetrical wheel spoke or sunrays, centred by a foveal pigmented lesion. En face SS‐OCT showed patterned retinal folds and B‐Scan SS‐OCT showed a thick hyperreflective layer above the internal limiting membrane (ILM) associated to underlying retinal surface wrinkling. We also noted thickened disorganized retinal layers, ectopic inner foveal layers (EIFL) and loss of the foveal depression. The central bouquet assessed the presence of subretinal hyperreflective vitelliform‐like deposit associated to intraretinal hyperreflective foci corresponding to pigment migration.Conclusion: This case corresponds to the final stage ERM of Govetto classification. It reveals a migration process of retinal pigment cells towards inner retinal layers. The advent of high‐resolution SS‐OCT offered a better detection of ERM stages and alterations of the central bouquet, in order to improve our pathophysiological understanding. In fact, many hypotheses on ERM development processes were suggested. Glial cells and retinal pigment epithelial cells would undergo trans‐differentiation to a myofibroblastic pre‐retinal cells through the retina, via microdefects above ILM. Accumulated myofibroblastic cells, along with extracellular matrix deposition are the main precursors of ERM.

Integrity of the Hyperreflective Layer in the Inner Choroid in Eyes with Drusen.

This study aimed to compare the integrity of the hyperreflective layer of the inner choroid in eyes with and without drusen. Swept-source optical coherence tomography images of patients with drusen and normal controls were reviewed. Using a line plot of ImageJ, choroidal reflectivity was measured at the subfovea, and the integrity of the hyperreflective layer of the inner choroid was determined. In total, 63 eyes with drusen and 30 control eyes without drusen were included. The integrity of the hyperreflective layer of the inner choroid was preserved in 81.0% of eyes with drusen and 93.3% of normal controls. The proportion of eyes with the hyperreflective layer did not differ between eyes with and without drusen. Of the 63 subjects with drusen, this hyperreflective layer was observed in all 28 eyes (100%) with pachydrusen but only in 68.6% of the 35 eyes with soft drusen, and its prevalence was significantly different (P = 0.001). The prevalence of the hyperreflective layer between the choriocapillaris and medium or large choroidal vessels in eyes with soft drusen differed from that in eyes with pachydrusen. These findings support the suggestion that changes within the choroidal stroma may be involved in the pathogenesis of age-related macular degeneration.

Epiretinal implant of human amniotic membrane to treat highly myopic macular hole retinal detachments: A novel surgical technique.

To describe a new surgical technique involving the use of a human amniotic membrane (hAM) epiretinal patch to treat a primary macular hole retinal detachment (MHRD) in a highly myopic patient. A 60 years old highly myopic man was referred to our clinic with a diagnosis of MHRD in his right eye. The patient was pseudophakic, with a visual acuity of counting fingers at the baseline evaluation. Pars plana vitrectomy was performed, a small retinotomy was created at the inner margin of the staphyloma, and membrane blue dual was used to obtain an adequate peeling of the inner limiting membrane. Then, a 1.5 mm diameter circular hAM patch was obtained and positioned over the macular hole with the chorion layer settled over the retina. After a complete fluid-air exchange, 20% sulfur hexafluoride gas was used as endotamponade, and the patient was asked to remain face down for three days. Four weeks after surgery, optical coherence tomography (OCT) scan showed the hAM patch, visualized as a distinct hyperreflective layer well integrated with the retina. Nine months after surgery, the macular hole was closed, the retina reattached, the hAM patch was adherent to the retina, and the patient presented a best-corrected visual acuity improved to 0.7 logMar. No postoperative adverse events were registered during the follow-up. Epiretinal hAM implant could represent a novel surgical technique, feasible and easier compared to other current techniques used to treat MHRD in highly myopic patients.

The role of anterior segment optical coherence tomography in the evaluation of the pterygium

BackgroundTo evaluate the ability of anterior segment optical coherence tomography (AS-OCT) to visualize the anatomic features of the pterygium and its invasion of the corneal layers. MethodsSeventy-five eyes of 54 patients diagnosed with pterygium were included. All subjects underwent complete ophthalmologic examinations, including AS-OCT. The limbus–apex distance, vertical height at the limbus, invasion of the Bowman's and stromal layers, and other morphologic structures of the pterygium tissue were analyzed. ResultsThe mean age of the patients was 49.67 ± 16.49 (20–85) years. The mean apex–limbus distance was 2548.37 ± 1026.32 (933–4597) μm, and the mean vertical height at the limbus was 4843.89 ± 1374.10 (1740–7784) μm. A space was observed beneath the pterygium tissue in 44 (58.67%) eyes. The mean width and height of this space were 1756.33 ± 560.22 (1009–3095) μm and 231.70 ± 85.88 (109–465) μm, respectively. Invasion of the Bowman's layer was apparent in 74 (98.67%) eyes, and invasion of the stromal layer was detected in 33 (44%) eyes. A hyperreflective layer was observed beneath the epithelial layer at the edge of the pterygium apex in 31 (41.33%) eyes. In 24 (92.31%) of the 26 advanced pterygium cases and 20 (40.82%) of the 49 early pterygium cases, a subpterygium space was found beneath the lesion (p = 0.0001). ConclusionAS-OCT enables measurement of the actual size and thickness of pterygia, assessment of invasion of the Bowman's and stromal layers of the cornea, and evaluation of the pterygium structure. Over half of the eyes exhibited space beneath the pterygium.

Biomarkers of Vitreous Cortex Remnants in Eyes With Primary Rhegmatogenous Retinal Detachment.

The purpose of this study was to identify pre-operative biomarkers of vitreous cortex remnants (VCRs) in eyes with rhegmatogenous retinal detachment (RRD). Prospective case series of 103 eyes treated with pars plana vitrectomy (PPV) to repair RRD. Pre-operatively, optical coherence tomography (OCT) and B-scan ultrasonography (US) were used to study the vitreo-retinal interface and vitreous cortex status. If detected during PPV, VCRs were removed. Images acquired pre-operatively were compared with intra-operative findings and with postoperative OCT images taken at 1, 3, and 6 months of follow-up. Multivariate regression analyses were performed to determine associations between VCRs and pre-operative variables. The presence of VCRs at the macula (mVCRs) and at the periphery (pVCRs), was ascertained intra-operatively in 57.3% and 53.4% of the eyes, respectively. Pre-operatively, a preretinal hyper-reflective layer (PHL) and a saw-toothed aspect of the retinal surface (SRS) were identified with OCT in 73.8% and 66% of the eyes, respectively. US sections showed a vitreous cortex running close and parallel to the detached retina upon static and kinetic examination (the "lining sign") in 52.4% of the cases. Multivariate regression analyses showed an association between PHL and SRS and intra-operative evidence of mVCRs (P = 0.003 and < 0.0001, respectively) and between SRS and "lining sign" and pVCRs (P = 0.0006 and 0.04, respectively). PHL and SRS on OCT and the "lining sign" on US appear to be useful pre-operative biomarkers of the intra-operative presence of VCRs. Preoperative identification of VCRs biomarkers may help to plan the operating strategy in eyes with RRD.

Выяснение причин отслойки нейроэпителия с целью постановки корректного диагноза у пациентов с патологией макулярной области

Purpose. To assess the difficulties of finding out true cause of detachment of neuroepithelium in patients with various retinal pathologies. Material and methods. 3 patients (3 eyes) aged 51 to 59 years with complaints of sensation of a “spot» in front of the eye, decreased vision and metamorphopsia. The best corrected visual acuity ranged from 0.4 to 0.5. Rounded local prominating lesion – zones of local detachment of neuroepithelium, zones of local atrophy or defects in retinal pigment epithelium (RPE) were determined in all 3 eyes in the posterior pole of the eye. Results. According to results of optical coherence tomography (OCT), all 3 eyes had local serous detachment of neuroepithelium from 250 to 270 µm, local inclusions characterized by hyperreflective and heterogeneous RPE layer, episodically located in its layers hyperreflective areas with point breach in the Bruch membrane (“hard» drusen). Irregular RPE elevations (“wavy pattern») with its local fibrovascular detachment were determined. According to the results of OCT angiography, hyperreflective zones of the presence of a neovascular network in the layer of choriocapillaries under the areas of fibrovascular detachment of RPE, coinciding with zones of hyperautofluorescence, were revealed in all 3 eyes. In paired eyes of all 3 patients, “hard» retinal drusen in the macular zone were detected. Conclusions. 1. All 3 eyes were diagnosed with the wet form agerelated macular degeneration due to: their belonging to the older age group, low corrected visual acuity, the presence of complaints of metamorphopsia, irregular elevation and local fibrovascular detachment of RPE, the presence of local hyperautofluorescence, and presence of drusen on the double eye. 2. The use of OCT angiography makes it possible to differentiate between central serous chorioretinopathy and age-related macular degeneration by detecting choroidal neovascularization. Keywords: central serous chorioretinopathy, wet AMD, detachment of neuroepithelium

Post-operative visual outcomes based on morphological staging of idiopathic epiretinal membranes on OCT.

To evaluate the recently described optical coherence tomography (OCT) based classification of epiretinal membrane (ERM) and its usefulness in predicting the functional outcome. A retrospective observational review of OCT scans of patients with the diagnosis of idiopathic ERM was carried out from January 2016 to June 2021. All consecutive images diagnosed with any stage of idiopathic ERM and fulfilled the eligibility criteria were included in the analysis. ERM was identified on OCT scans as a thin hyperreflective layer over the inner layers of retina. OCT scans of patients with ERM who underwent vitrectomy, were independently staged as per the new classification by two independent retinal surgeons to form a consensus on stage. Best corrected visual acuity (BCVA) in logMAR scale and central subfield thickness (CST) on pre- and post-operative spectral domain OCT scans were the variables noted for all patients at the time of diagnosis and at 6 and 12mo follow up visit after undergoing intervention. Partial correlation coefficient was computed between BCVA (logMAR) and CST by ERM stage adjusting by baseline measures. Clinical charts of 74 patients with idiopathic ERM were assessed. Clinically significant improvement in BCVA overtime was observed with significant difference in median visual acuity of patients with Stage II-IV ERM with P<0.001. The median CST of all patients with stage II-IV ERM showed similar consistent improvement with P<0.001 from baseline to 12th month. Our results showed not only gain in visual acuity but also shift from baseline to anatomical normalization of CST in stage II. We found a decrease in CST with difference of 166 µm and 151 µm in stage III and stage IV respectively. Our results remained consistent with the hypothesis of improved visual outcomes with all stages of ERM with adjusted moderate linear correlation between visual acuity and CST in stage II-IV (r>0.3). Equally significant visual outcomes of patients with ERM staged II-IV and therefore can be counselled for improved visual acuity after surgical removal of ERM with improvement up to 5 lines on Snellen's chart from the baseline.

Hyperreflective Membrane at the Vitreoretinal Interface in Diabetic Macular Edema: A Finding in Ultra-High-Resolution Optical Coherence Tomography.

PurposeDetecting subtle vitreoretinal interface (VRI) findings, such as a posterior hyaloid membrane, is difficult with conventional retinal imaging. We compared ultra-high-resolution spectral domain optical coherence tomography (UHR-SD-OCT) with standard-resolution OCT (SD-OCT) for the imaging of VRI abnormalities in diabetic retinopathy (DR).MethodsThis prospective cross-sectional study included 113 consecutive patients (91 patients with diabetes and 22 healthy controls). The VRI was evaluated, and the results were compared between the conventional SD-OCT and UHR-SD-OCT images. VRI findings were also investigated before and after internal limiting membrane peeling during vitrectomy for proliferative DR.ResultsA total of 159 eyes (87.4%) of 91 patients with diabetes were analyzed. UHR-SD-OCT could detect a hyperreflective layer at the VRI, in which en face OCT showed a membrane-like structure, termed the hyperreflective membrane (HRMe). The preoperative HRMe could not be detected in all patients with proliferative DR who underwent internal limiting membrane peeling during vitrectomy. Although the HRMe did not correlate with the DR stage, eyes with diabetic macular edema (DME) (64.5%) showed a significant HRMe with UHR-SD-OCT more frequently than those without DME (35.8%) (P = 0.005).ConclusionsUHR-SD-OCT can detect the HRMe at the VRI in DR eyes, particularly in eyes with DME. The HRMe may present a thickened posterior hyaloid membrane that contributes to DME development.Translational RelevanceUHR-SD-OCT detects slight changes in the VRI in DR eyes. In the future, it may help to elucidate the mechanism of DME formation.

Дифференциальная диагностика аваскулярных и васкуляризированных отслоек ретинального пигментного эпителия при возрастной макулярной дегенерации

Purpose. Тo evaluate of differential diagnostic signs using optical coherence tomography in patients with avascular and vascularized serous retinal pigment epithelium detachment (RPE) in age-related macular degeneration (AMD). Material and methods. 40 people with AMD were examined. The patients were divided into two groups: avascular (20 patients) and vascularized (20 patients) serous RPE detachment. All patients underwent a standard ophthalmological examination and additional research methods: determination of the maximum corrected visual acuity using to the ETDRS (Early Treatment Diabetic Retinopathy Study) charts, OCT, OCT angiography. Results. Comparative analysis of OCT signs revealed that avascular serous RPE detachment is characterized by the presence of neuroepithelial detachment at the top of the RPE detachment (p = 0.002), neuroepithelial detachment is located within a triangle with the apex at the level of the inner limiting membrane of the retina, with a bisector drawn from the apex of the triangle through the point of maximum height RPE detachment and lateral sides that are tangent to the sides of the RPE detachment (p = 0.004). The presence of vascularized serous RPE detachment is characterized by intraretinal fluid (p = 0.002), prominence of the top of the RPE detachment (p = 0.009), thickness of the RPE at the top of the RPE detachment is greater than at the base (p = 0.006), hyperreflective layer under the RPE (p &lt; 0.005), an increase in the hyperreflectivity of photoreceptors on the top of the RPE detachment relative to the base (p = 0.009). Conclusions. The identified differential diagnostic criteria make it possible to choose an adequate tactics for the treatment of patients with serous RPE detachment in age-related macular degeneration, depending on the identified form – vascularized or avascular. Keywords: retinal pigment epithelium detachment, age-related macular degeneration.

Correlation of Intravascular Ultrasound with Histology in Pediatric Pulmonary Vein Stenosis.

Preliminary intravascular ultrasound (IVUS) images of suspected pediatric intraluminal pulmonary vein stenosis (PVS) demonstrate wall thickening. It is unclear how the IVUS-delineated constituents of wall thickening correlate with the histology. We analyzed six postmortem formalin-fixed heart/lung specimens and four live patients with PVS as well as control pulmonary veins using IVUS and light microscopic examination. In PVS veins, IVUS demonstrated wall thickening with up to two layers of variable echogenicity, often with indistinct borders. Histologically, the veins showed fibroblastic proliferation with areas rich in myxoid matrix as well as areas with abundant collagen and elastic fibers. Discrete vein layers were obscured by scarring and elastic degeneration. A lower reflective periluminal layer by IVUS corresponded with hyperplasia of myofibroblast-like cells in abundant myxoid matrix. The hyper-reflective layer by IVUS extended to the outer edge of the vessel and corresponded to a less myxoid area with more collagen, smooth muscle and elastic fibers. The outer less reflective edge of the IVUS image correlated with a gradual transition into adventitia. Normal veins had a thin wall, correlating with histologically normal cellular and extracellular components, without intimal proliferation. IVUS may provide further understanding of the anatomy and mechanisms of pediatric pulmonary vein obstruction.

Scars of an old story: Laser pointer injury

A 12-year-old boy presented to us with complaints of nonprogressive diminution of vision and seeing a black spot at the center of his visual field in his right eye following exposure to a red laser pointer accidentally, while playing, 2 years ago. On examination, his best-corrected visual acuity was 6/12 OD and 6/6 OS. His anterior segment examination was clinically normal. Fundus examination revealed a well-defined, pigmented, slightly elevated, hypoautofluorescent scar involving the nasal parafoveal region of the macula in his right eye. His left fundus appeared normal. Optical coherence tomography (swept source) imaging showed an irregular, raised, hyperreflective inner layer with back-shadowing in the parafoveal region corresponding to the pigmented scar seen in his right eye. Laser pointer injuries are fairly common but under-reported health hazard.

The Descemet Membrane in Primary Congenital Glaucoma.

To evaluate Descemet membrane (DM) morphology in eyes with primary congenital glaucoma (PCG) in vivo using high-definition anterior segment optical coherence tomography (ASOCT) and on histopathology. Corneal scans of patients with PCG (22 eyes of 15 patients) were evaluated for DM morphology and anterior chamber angle using ASOCT. The DM thickness in PCG eyes was compared with fellow eyes (8 eyes) of unilateral patients with PCG and healthy controls (12 eyes) on ASOCT. The DM morphology was also compared on the histopathology of corneal tissues (9) obtained from PCG eyes after keratoplasty and enucleated eyes of retinoblastoma (6 controls) on light microscopy with immunostaining for collagen IV. On ASOCT, all affected eyes showed the presence of either a thickened DM complex or a hyper-reflective double layer representing the thickened DM and pre-Descemet layer (PDL), unlike a single membrane in the controls and fellow eyes. On ASOCT, among patients with PCG, the DM showed significant thickening (32.0 ± 11.2 μm) versus fellow eyes (14.4 ± 3.3 μm) and controls (11.5 ± 1 μm) (P < 0.001; analysis of variance). The thickened DM complex continued peripherally into the trabecular meshwork as an abnormal membrane in 16/22 affected eyes. On histopathology, thickening of DM was also more among PCG eyes (median: 67.9 μm range: 27.2-214.9) versus controls (median: 27.7 μm, range: 22.1-36.1; P = 0.005) as also of PDL (median: 14 μm, range: 5.9-30.5) of PCG versus (median 3.5, range: 1.3-6.7 μm) in controls; P = 0.014. Thickening of DM and PDL occurs in eyes with PCG and is seen to have a peripheral extension upto the angle recess.

Presumed activated retinal astrocytes and Müller cells in healthy and glaucomatous eyes detected by spectral domain optical coherence tomography.

PurposeTo investigate presumed activated retinal astrocytes and Müller cells (ARAM) detected by scanning laser ophthalmoscopy (SLO) and spectral domain optical coherence tomography, and to investigate its presence in healthy controls as well as its relationship to posterior vitreal detachment (PVD) and glaucoma.MethodsThis retrospective study involved 1337 eyes of 805 controls between ages 8 and 90, and 250 eyes of 146 patients with glaucoma between the ages of 28 and 95. Subjects were counted as possessing ARAM only if they met the following criteria: (1) a patchy, discrete, glittering appearance on SLO, (2) a distinct, flat, hyper‐reflective layer at the internal limiting membrane on at least one B‐scan crossing the glittering area and (3) absence of any surface wrinkling retinopathy. The diagnosis of PVD was based on both the patient’s clinical examination and imaging data. Frequency tables were used to describe categorical variables and differences were compared by means of χ2. Analyses were separated based on right and left eye, first on controls and then between glaucomatous eyes and age‐similar sex‐matched controls.ResultsARAM was found in both healthy controls and patients with glaucoma at similar frequencies. There was no association between having glaucoma and the presence of ARAM. ARAM was not different between the sexes but was associated with age and having a PVD.ConclusionsThis large retrospective study found that ARAM can be seen in healthy controls, is associated with PVD and possibly independently with age, and occurred at similar frequency in glaucomatous eyes.

Spontaneous regression of epithelial downgrowth from clear corneal phacoemulsification wound

PurposeTo report a case of spontaneous regression of optical coherence tomography (OCT) and confocal microscopy-supported epithelial downgrowth associated with clear corneal phacoemulsification wound. ObservationsA 66-year-old Caucasian male presented two years after phacoemulsification in the left eye with an enlarging cornea endothelial lesion in that eye. His early post-operative course had been complicated by corneal edema and iris transillumination defects. The patient presented to our clinic with a large geographic sheet of epithelial downgrowth and iris synechiae to the temporal clear corneal wound. His vision was correctable to 20/25 in his left eye. Anterior segment OCT showed a hyperreflective layer on the posterior cornea with an abrupt transition that corresponded to the clinical transition zone of the epithelial downgrowth. Confocal microscopy showed polygonal cells with hyperreflective nuclei suggestive of epithelial cells in the area of the lesion with a transition to a normal endothelial cell mosaic. Given the lack of glaucoma or inflammation and the relatively good vision, the plan was made to closely monitor for progression with the anticipation that he may require aggressive surgery. Over course of subsequent follow-up visits at three, seven and ten months; the endothelial lesion receded significantly. Confocal imaging in the area of the previously affected cornea showed essentially normal morphology with anan endothelial cell count of 1664 cells/mm2. Conclusions and importanceEpithelial downgrowth may spontaneously regress. Though the mechanism is yet understood, contact inhibition of movement may play a role. Despite this finding, epithelial downgrowth is typically a devastating process requiring aggressive treatment.

Automated sub-retinal fluid detection comprising RPE-region using neighbouring pixel connectivity paradigm

Sub-Retinal Fluid (SRF), a categorized retinal fluid accumulation just above the Inner Hyper-Reflective Layer (HRL) of the RPE-Region has a significant correlation with visual acuity. Sub-Retinal Fluid are the indicators of Macular Hole (MH) formations. Early information regarding SRF may help in tackling the chronic cases, as surgery is the only option for treating MH. Proposed is a method to identify Retinal Pigment Epithelium (RPE) region in Optical Coherence Tomography (OCT) visualization of the retina, further based on it the retinal pathology called as Sub-Retinal Fluid is detected. This paper discusses the newly proposed method for the detection of RPE region, the non-separated region between the inner and outer Hyper-Reflective Layer (HRL). To the best of our knowledge, identification of Sub-Retinal fluid, has never been automated. The work validation is done with the ground truths (manually delineated by an expert panel). Evaluation of the system (RPE-Region detection and SRF Detection) is done independently for both the proposed methods. RPE-region detection was done on 220 images from 23 patients at different orientation styles with 90.45% correct detections whereas the sensitivity and the specificity for the SRF detection is found to be 89.74% and 89.36% respectively over 164 images from 30 patients.

Long-term Characterization of Retinal Degeneration in Royal College of Surgeons Rats Using Spectral-Domain Optical Coherence Tomography.

PurposeProspective treatments for age-related macular degeneration and inherited retinal degenerations are commonly evaluated in the Royal College of Surgeons (RCS) rat before translation into clinical application. Historically, retinal thickness obtained through postmortem anatomic assessments has been a key outcome measure; however, utility of this measurement is limited because it precludes the ability to perform longitudinal studies. To overcome this limitation, the present study was designed to provide a baseline longitudinal quantification of retinal thickness in the RCS rat by using spectral-domain optical coherence tomography (SD-OCT).MethodsHorizontal and vertical linear SD-OCT scans centered on the optic nerve were captured from Long-Evans control rats at P30, P60, P90 and from RCS rats between P17 and P90. Total retina (TR), outer nuclear layer+ (ONL+), inner nuclear layer (INL), and retinal pigment epithelium (RPE) thicknesses were quantified. Histologic sections of RCS retina obtained from P21 to P60 were compared to SD-OCT images.ResultsIn RCS rats, TR and ONL+ thickness decreased significantly as compared to Long-Evans controls. Changes in INL and RPE thickness were not significantly different between control and RCS retinas. From P30 to P90 a subretinal hyperreflective layer (HRL) was observed and quantified in RCS rats. After correlation with histology, the HRL was identified as disorganized outer segments and the location of accumulated debris.ConclusionsRetinal layer thickness can be quantified longitudinally throughout the course of retinal degeneration in the RCS rat by using SD-OCT. Thickness measurements obtained with SD-OCT were consistent with previous anatomic thickness assessments. This study provides baseline data for future longitudinal assessment of therapeutic agents in the RCS rat.

Imaging of 3D Tissue-Engineered Models of Oral Cancer Using 890 and 1300 nm Optical Coherence Tomography

© 2015, Nizhny Novgorod State Medical Academy. All rights reserved. Optical coherence tomography (OCT) generates its primary form of contrast from elastic backscatter. It is now the gold standard technique for retinal screening and is emerging rapidly in cardiovascular research however it remains a research goal to establish it to the same degree in epithelial cancer detection and diagnosis. In this report we compare two different OCT systems: an 890 nm spectrometer-based OCT system with 2.5 µm axial resolution and a 1300 nm swept-source OCT system with 7.5 µm axial resolution to determine the effect of these different OCT parameters on the endogenous backscatter contrast of dysplastic/malignant oral mucosa models relative to normal mucosa models. Tissueengineered oral mucosa models constructed with a dysplastic cell line (DOK), a malignant cell line (Cal27) and normal cell were imaged with both of these OCT platforms and comparisons made with regard to apparent epithelial thickness and the visibility of the epithelium relative to the underlying stroma. For the Cal27’s, hematoxylin and eosin staining confirmed the formation of a keratinized layer superficial to a thickened layer of viable cells on top of the stroma. The keratinized layer presented as a hyperreflective thickened layer superficial to a darker region on both OCT platforms. The keratinized layer caused a steep fall in signal at 890 nm, making it difficult to visualise underlying structures, whereas 1300 nm OCT clearly visualized both the epithelial cells and the stroma lying beneath. For the DOK cells, hematoxylin and eosin staining confirmed the formation of an epithelial layer frequently presenting an abnormal morphology especially at the epidermal/stromal junction, with features such as infiltrating, bulbous rete pegs. These were more clearly visualized under 890 nm OCT. These observations show that 890 nm OCT retains some of its known advantages of higher contrast between anatomical tissue layers when used to observe dysplastic and malignant 3D oral mucosa constructs. However 1300 nm OCT is confirmed to possess a greater ability to image the full thickness of the model epithelia and in particular it is more suited to imaging through the keratinized layer.

Reflectance confocal microscopy of mucosal pigmented macules: a review of 56 cases including 10 macular melanomas

Although most mucosal pigmented macules are benign, it can be clinically challenging to rule out an early melanoma. Reflectance confocal microscopy (RCM) is a noninvasive imaging technique useful in discriminating between benign and malignant skin lesions. To describe the confocal aspects of benign and malignant mucosal pigmented macules with histopathological correlations. We retrospectively reviewed the confocal images of 56 labial or genital pigmented macules including 10 macular melanomas. According to the retrospective natureof the study, we evaluated the recorded images chosen by the physicians that performed the RCM examination for each case. In benign macules, the most frequently observed pattern was a ringed pattern characterized by round or polycyclic papillae, with a hyper-reflective basal layer; another pattern was characterized by sparse bright dendritic cells in the basal layer, the basal epithelial cells being otherwise less reflective. Roundish cells, a high density of dendritic cells with atypias and intraepithelial bright cells were clues to the presence of malignancy. Reflectance confocal microscopy seems to be a valuable tool to noninvasively differentiate benign from malignant mucosal pigmented macules and target biopsies in cases of equivocal features.

Curvature correction of retinal OCTs using graph-based geometry detection

In this paper, we present a new algorithm as an enhancement and preprocessing step for acquired optical coherence tomography (OCT) images of the retina. The proposed method is composed of two steps, first of which is a denoising algorithm with wavelet diffusion based on a circular symmetric Laplacian model, and the second part can be described in terms of graph-based geometry detection and curvature correction according to the hyper-reflective complex layer in the retina. The proposed denoising algorithm showed an improvement of contrast-to-noise ratio from 0.89 to 1.49 and an increase of signal-to-noise ratio (OCT image SNR) from 18.27 to 30.43 dB. By applying the proposed method for estimation of the interpolated curve using a full automatic method, the mean ± SD unsigned border positioning error was calculated for normal and abnormal cases. The error values of 2.19 ± 1.25 and 8.53 ± 3.76 µm were detected for 200 randomly selected slices without pathological curvature and 50 randomly selected slices with pathological curvature, respectively. The important aspect of this algorithm is its ability in detection of curvature in strongly pathological images that surpasses previously introduced methods; the method is also fast, compared to the relatively low speed of similar methods.