Optical Coherence Tomography Measurements Research Articles

Agreement between intraoperative and anterior segment optical coherence tomography measurements of the extraocular muscle insertion distance in patients with previous strabismus surgery

PurposeTo evaluate the agreement between anterior segment optical coherence tomography (AS-OCT) measurement of preoperative distance from the limbus to the horizontal rectus muscles insertion and intraoperative measurement in patients who have previously undergone strabismus surgery and required reoperation. MethodsSubjects from two ophthalmological centers were included. Preoperative AS-OCT was used to measure the muscle insertion from the limbus, and intraoperative measurements were obtained using calipers. Interclass correlation coefficient and Bland-Altman agreement analysis were used. ResultsA total of 53 horizontal rectus muscles from 24 patients with previous strabismus surgery were analyzed: 27 medial rectus (MR) and 26 lateral rectus (LR) muscles, including both previously operated and previously unoperated muscles. Average AS-OCT measurements of MR was 8.54 ± 2.42 mm and intraoperatively was 9.4 ± 3.09 mm. Average AS-OCT for LR was 8.32 ± 2.25 mm and intraoperatively was 9.34 ± 3.73 mm. 63% of MR muscles and 77% of LR muscles were within 1 mm between AS-OCT and intraoperative measurement. Spearman’s correlation coefficient showed positive correlation between measures for both MR and LR muscles. The interclass correlation coefficient was 0.79 (95% CI, 0.56-0.90) for MR muscles and 0.70 (95% CI, 0.44-0.85) for LR muscles, with a good agreement. Agreement was better for muscles ≤10 mm from the limbus (which included both previously operated and unoperated muscles) than for muscles found >10 mm from the limbus. ConclusionsGood agreement was observed between the measurement of limbus-insertion distance obtained by AS-OCT and by intraoperative measurement, especially when the muscle insertion was ≤10 mm from the limbus.

Value of Combined Optical Coherence Tomography and Optical Flow Ratio Measurements After Percutaneous Coronary Intervention

BackgroundOptical flow ratio (OFR) is a novel computational fractional flow reserve derived from optical coherence tomography (OCT). However, the impact of combining post-stenting morphology (OCT) and physiology (OFR) remains largely unknown. MethodsOCT and OFR were analysed at an independent core laboratory. Target lesion failure (TLF) was defined as the composite of cardiac death, target lesion myocardial infarction, and target lesion revascularisation. Suboptimal stent deployment was identified with at least 1 TLF-related OCT or OFR characteristic. ResultsA total of 448 patients with acute coronary syndrome (459 vessels) were assessed. Stent expansion < 80%, minimal stent area < 4.5 mm2, stent edge lipid-rich plaque and OFR < 0.90 were independent predictors of TLF (all P < 0.001). Patients with OCT-suboptimal (adjusted hazard ratio [aHR] 7.88, 95% CI 2.73-22.72,-P < 0.001) or OFR-suboptimal (aHR 5.78, 95% CI 2.54-13.14; P < 0.001) stent deployment showed significantly higher risk of TLF compared with those with optimal stent deployment, with a significant interaction (Pinteraction < 0.001). OCT and OFR both–suboptimal stent deployment was confirmed as an independent predictor of TLF (aHR 9.39, 95% CI 4.25-20.76; P < 0.001). ConclusionsCombined OCT and OFR conferred an optimal reclassification of stent deployment, which may aid in decision making regarding a tailored PCI strategy for optimal stent deployment.

Discrimination of healthy oral tissue from oral cancer based on the mean grey value determined by optical coherence tomography

ObjectiveThis study aimed to identify a quantitative index for optical coherence tomography (OCT) images to discriminate tumours from surrounding tissues.Subjects and methodsBased on OCT measurements, mean grey values were determined from 432 locations on fifty-four human tissue specimens (eighteen cancerous, para-cancerous, and normal tissues each). These results were histologically evaluated by hematoxylin and eosin staining (H&E).ResultsThe mean grey values of oral squamous cell carcinoma (OSCC) measurements were significantly different from those of the surrounding healthy tissue (p value < 0.0001), with the former being higher. The sensitivity and specificity of detecting tumourous tissue using this approach were 93 and 94%, respectively.ConclusionsOCT as a non-invasive, real-time imaging method, correlates well with H&E pathological images. It can effectively distinguish squamous cell carcinoma from normal tissues with high sensitivity and specificity and is thus expected to assist and guide tumour margin evaluation.Clinical relevanceThis discovery highlights the potential of OCT in the objective evaluation of tumour margin during surgery.

Assessment of ganglion cell complex thickness and its correlation with retinal sensitivity using microperimetry 6 months after epiretinal membrane surgery

PurposeTo verify the correlation between the full-macular and the ganglion cell complex (GCC) thickness measurements and retinal sensitivity (RS) assessed by microperimetry (MP) 6 months after surgical peeling for idiopathic epiretinal membrane (ERM).MethodsForty-three were submitted to pars-plana posterior vitrectomy (PPV) with concomitant peeling of internal limiting membrane (ILM) for idiopathic ERM treatment. Best-corrected visual acuity (BCVA) and 3D volumetric high-definition optical coherence tomography (OCT) imaging were preoperatively acquired. Six months after the surgery, BCVA, OCT imaging, and RS measured by MP were assessed. For the OCT parameters, we analyzed both the full-macular and the ganglion cell layer complex (GCC) thicknesses. The MP parameters tested were 44 points covering 20 central degrees (6 mm), with direct correspondence with the nine sectors of the OCT-ETDRS map. This approach enables the direct topographic correlation between the structure and functional measurements. The OCT and MP exam measurements were also performed in 43 eyes of age-matched healthy controls. Correlations between BCVA, RS, and OCT parameters were examined.Results All patients exhibited a substantial improvement in visual acuity following surgery. The RS parameters were significantly lower in patients compared to the controls. The full-macular thickness measurements were thicker than controls preoperatively and significantly reduced postoperatively; however, remaining significantly higher than controls, in the 4 inner sectors, at the fovea and for the average macular thickness. Preoperative GCC measurements were higher than those in controls. There was a significant reduction in GCC thickness in all sectors postoperatively, especially in the outer sectors, as well as in the average macular thickness. A positive correlation was found between full-macular and GCC thickness and RS postoperatively in several sectors.ConclusionsOur results demonstrate that ERM peeling can improve visual acuity in the postoperative period. However, RS may not fully restore, remaining significantly lower when compared to the controls. Both full-macular and GCC thickness measurements were reduced 6 months after surgery. However, significant thinning of the GCC thickness was observed when compared to the normal control eyes, indicating the occurrence of some degree of ganglion cell layer atrophy. We have demonstrated significant correlations among various OCT thickness parameters, particularly for GCC measurements. We believe that GCC integrity may play an important role in visual function after ERM surgery, and that MP may help better understand the correlations between structural and functional findings following ERM surgery.

Investigating the impact of OCT imaging of the crystalline lens on the accuracy and precision of cataract assessment.

To determine if supplementing standard clinical assessments with Optical Coherence Tomography (OCT) imaging of the crystalline lens improves the accuracy and precision of lens opacity assessment and associated clinical management decisions by optometrists. Fifty optometrists registered in the UK or Éire undertook a clinical vignette study where participants graded lens opacities and made associated clinical management decisions based on the image(s)/information displayed. Three forms of vignettes were presented: (1) Slit-lamp (SL) images of the lens, (2) SL and OCT images and (3) SL, OCT and visual function measures. Vignettes were constructed using anonymised data from 50 patients with varying cataract severity, each vignette being presented twice in a randomised order (total vignette presentations = 300). The accuracy of opacity and management decisions were evaluated using descriptive statistics and non-parametric Bland-Altman analysis where assessments from experienced clinicians were the reference. The precision of assessments was examined for each vignette form using non-parametric Bland-Altman analysis. All (n = 50) participants completed the study, with 36 working in primary eyecare (primary eyecare) settings and 14 in hospital eyecare services (HES). Agreement was highest where vignettes contained all clinical data (i.e., SL, OCT and visual function data-grading: 51.0%, management: 50.5%), and systematically reduced with decreasing vignette content (p < 0.001). A larger number of vignettes containing imaging and visual function measures exhibited below reference (i.e., less conservative) grading compared with vignettes containing imaging data alone (all p < 0.05). HES-based optometrists were more likely to grade lens opacities lower than clinicians working in primary eyecare (p < 0.001). Good measurement precision was evident for all vignettes, with a mean bias close to zero and limits of agreement below one grading step for all conditions. The addition of anterior segment OCT to SL images improved the accuracy of lens opacity grading. Structural assessment alone yielded more conservative decision making, which reversed once visual functional data was available.

The contribution of paramagnetic rim and cortical lesions to physical and cognitive disability at multiple sclerosis clinical onset: evaluating the power of MRI and OCT biomarkers.

In multiple sclerosis (MS), imaging biomarkers play a crucial role in characterizing the disease at the time of diagnosis. MRI and optical coherence tomography (OCT) provide readily available biomarkers that may help to define the patient's clinical profile. However, the evaluation of cortical and paramagnetic rim lesions (CL, PRL), as well as retinal atrophy, is not routinely performed in clinic. To identify the most significant MRI and OCT biomarkers associated with early clinical disability in MS. Brain, spinal cord (SC) MRI, and OCT scans were acquired from 45 patients at MS diagnosis to obtain: brain PRL and non-PRL, CL, SC lesion volumes and counts, brain volumetric metrics, SC C2-C3 cross-sectional area, and retinal layer thickness. Regression models assessed relationships with physical disability (Expanded Disability Status Scale [EDSS]) and cognitive performance (Brief International Cognitive Assessment for Multiple Sclerosis [BICAMS]). In a stepwise regression (R2 = 0.526), PRL (β = 0.001, p = 0.023) and SC lesion volumes (β = 0.001, p = 0.017) were the most significant predictors of EDSS, while CL volume and age were strongly associated with BICAMS scores. Moreover, in a model where PRL and non-PRL were pooled, only the contribution of SC lesion volume was retained in EDSS prediction. OCT measures did not show associations with disability at the onset. At MS onset, PRL and SC lesions exhibit the strongest association with physical disability, while CL strongly contribute to cognitive performance. Incorporating the evaluation of PRL and CL into the initial MS patient assessment could help define their clinical profile, thus supporting the treatment choice.

The thickness of the retinal nerve fiber layer, macula, and ganglion cell-inner plexiform layer in people with drug-resistant epilepsy.

Using Optical coherence tomography (OCT), we evaluated the association between peripapillary retinal nerve fiber, macular thickness, macular ganglion cell-inner plexiform layer, and drug resistance. In this cross-sectional study, we recruited people diagnosed with epilepsy and healthy controls. People with epilepsy were further stratified as drug-resistant or non-drug-resistant based on their response to anti-seizure medications. OCT measurements were conducted, and findings in right eye were analyzed. Fifty-one drug-resistant participants, 37 non-drug-resistant, and 45 controls were enrolled. The average peripapillary retinal nerve fiber layer, ganglion cell-inner plexiform layer, and macular thickness were thinner in the epilepsy groups than in controls. The drug-resistant group had significantly lower average ganglion cell-inner plexiform layer thickness (p = 0.004) and a higher proportion of abnormal/borderline GC/IPL thickness (p = 5.40E-04) than the non-drug-resistant group. Nevertheless, no significant differences were seen between the average thickness of peripapillary retinal nerve fiber and macular thickness. The temporal sectors of these three parameters were also significantly thinner in the drug-resistant group than in the non-drug-resistant. In a multivariate regression model, drug resistance was an independent predictor of reduced ganglion cell-inner plexiform thickness (Odds ratios OR = 10.25, 95% CI 2.82 to 37.28). Increased seizure frequency (r = -0.23, p = 0.039) and a higher number of anti-seizure medications ever used (r = -0.27, p = 0.013) were negatively associated with ganglion cell-inner plexiform layer thickness. Individuals with drug-resistant epilepsy had a consistent reduction in average ganglion cell-inner plexiform layer thickness and the temporal sector of peripapillary retinal nerve fiber layer and macular thickness. This suggests that ganglion cell-inner plexiform layer thickness could potentially serve as an indicator of the burden of drug resistance, as it correlated with reduced thickness in individuals having more frequent seizures and greater exposure to ASMs. In our study, we used a special tool called OCT to measure how thick the retina is in people with epilepsy and in healthy control. We found that the retina was consistently thinner in all areas for those with epilepsy compared to healthy control. Particularly, a specific layer called the ganglion cell-inner plexiform layer was a lot thinner in the group that didn't respond to medications, and this thinning was related to how often seizures occurred and how much medications were taken. Also, certain parts of the retina were thinner in the drug-resistant group.

Effect of Buerger’s disease on ocular microvascular structure

ABSTRACT Clinical relevance Buerger’s disease, being a systemic inflammatory vasculopathy, may present with ocular findings. Background This study aims to understand the potential role of optical coherence tomography and angiography findings in evaluating the course of Buerger’s disease. Methods This was a prospective, cross-sectional study that included 25 patients with Buerger’s disease (Group 1) and 51 healthy control participants, of whom 27 were smokers (Group 2) and 24 were non-smokers (Group 3). Following a detailed ophthalmic examination, optical coherence tomography and angiography measurements were conducted on participants. The values of macular superficial and deep capillary plexus, peripapillary capillary plexus vessel density measurements were taken into account from optical coherence tomography angiography measurements. Furthermore, measurements were taken for the parameters of the foveal avascular zone, including its area, perimeter and acircularity index. Additionally, the choriocapillaris flow area was assessed between radii of 1 mm, 2 mm, and 3 mm. Results In patients with Buerger’s disease, the area and perimeter of the foveal avascular zone were higher than in both smoker and non-smoker healthy groups (p < 0.001 for all). The vessel densities in superficial capillary plexus were found to be lower in patients with Buerger’s disease compared to both smokers and non-smokers in all regions except the parafovea (p < 0.05 for all). The radial peripapillary capillary plexus vessel densities in the whole retina and peripapillary region were lower than those in the non-smoker group (p < 0.001 and p = 0.008). The choriocapillaris flow areas in all three radius were lower in the smoker group than in the non-smoker group (1 mm, p = 0.01; 2 mm, p = 0.005; 3 mm, p = 0.011) Conclusions Buerger’s disease extends beyond the extremities, affecting vascular density and tissue perfusion in the optic disc and macula, making it a systemic condition. This disease can have ocular involvement without causing serious ocular findings.

Intraoperative OCT to check the correct postimplant position of PreserfloTM.

This study was designed to examine the capacity of intraoperative optical coherence tomography (OCT) to predict the postimplant position of the glaucoma drainage device PreserfloTM. 13 eyes (mean age 65.42 (14.89) years) underwent PreserfloTM (Santen, Osaka, Japan) placement. Before surgery, participants were subjected to a comprehensive ophthalmic examination (intraocular pressure (IOP), cup to disk ratio (C/D), visual field, OCT, endothelial cell count). Anterior segment OCT scans were obtained intraoperatively using a Rescan 700 OCT system (Carl Zeiss Meditec, Inc., Oberkochen, Germany). One day postsurgery, anterior segment OCT using the Spectralis OCT (Heidelberg Engineering GmbH) was performed in a sitting position to capture the same chamber cross-section as before. The main outcome variables were tube-endothelium distance (T-E) and tube length (TL) in the anterior chamber measured using both OCT systems. Correlation between intraoperative and office measurements was examined through Pearson correlation (r) and intraclass correlation coefficients (ICC). Mean intraoperative and in-office T-E were 625.26 (SD 366.60) versus 561.16 (SD 364.62) µm respectively (p = 0.540). Intraoperative and in-office anterior chamber TL were 1386 (SD 701.82) and 1433.91 (SD 713.55) µm, respectively (p = 0.029). Excellent correlation was observed between both sets of T-E (r = 0.992; p = 0.008) and TL (r = 0.984; p = 0.016) values. Both OCT systems showed good agreement yielding ICCs of 0.992 (p < 0.001) for T-E and 0.995 (p = 0.001) for TL. Excellent correlation was observed between our intraoperative and postoperative OCT measurements. These results support the usefulness of intraoperative OCT to confirm the correct position of an implanted PreserfloTM microshunt.

Lycium barbarum glycopeptide promotes neuroprotection in ET-1 mediated retinal ganglion cell degeneration

BackgroundVascular dysregulation is one of the major risk factors of glaucoma, and endothelin-1 (ET-1) may have a role in the pathogenesis of vascular-related glaucoma. Fruit extract from Lycium Barbarum (LB) exhibits anti-ageing and multitarget mechanisms in protecting retinal ganglion cells (RGC) in various animal models. To investigate the therapeutic efficacy of LB glycoproteins (LbGP) in ET-1 induced RGC degeneration, LbGP was applied under pre- and posttreatment conditions to an ET-1 mouse model. Retina structural and functional outcomes were characterised using clinical-based techniques.MethodsAdult C57BL/6 mice were randomly allocated into four experimental groups, namely vehicle control (n = 9), LbGP-Pretreatment (n = 8), LbGP-Posttreatment (day 1) (n = 8) and LbGP-Posttreatment (day 5) (n = 7). Oral administration of LbGP 1 mg/Kg or PBS for vehicle control was given once daily. Pre- and posttreatment (day 1 or 5) were commenced at 1 week before and 1 or 5 days after intravitreal injections, respectively, and were continued until postinjection day 28. Effects of treatment on retinal structure and functions were evaluated using optical coherence tomography (OCT), doppler OCT and electroretinogram measurements at baseline, post-injection days 10 and 28. RGC survival was evaluated by using RBPMS immunostaining on retinal wholemounts.ResultsET-1 injection in vehicle control induced transient reductions in arterial flow and retinal functions, leading to significant RNFL thinning and RGC loss at day 28. Although ET-1 induced a transient loss in blood flow or retinal functions in all LbGP groups, LbGP treatments facilitated better restoration of retinal flow and retinal functions as compared with the vehicle control. Also, all three LbGP treatment groups (i.e. pre- and posttreatments from days 1 or 5) significantly preserved thRNFL thickness and RGC densities. No significant difference in protective effects was observed among the three LbGP treatment groups.ConclusionLbGP demonstrated neuroprotective effects in a mouse model of ET-1 induced RGC degeneration, with treatment applied either as a pretreatment, immediate or delayed posttreatment. LbGP treatment promoted a better restoration of retinal blood flow, and protected the RNFL, RGC density and retinal functions. This study showed the translational potential of LB as complementary treatment for glaucoma management.

Choroidal Vascularity and Axial Length Elongation in Highly Myopic Children: A 2-Year Longitudinal Investigation.

To examine the influence of subfoveal choroidal thickness (SFCT) and choroidal vascularity index (CVI) on axial length (AL) elongation over a 2-year period in highly myopic children. In this is prospective, longitudinal, observational study, 163 participants (74%), who were 8 to 18years of age with bilateral high myopia (sphere ≤ -6.0 D) and without pathologic myopia, completed follow-up visits over 2years. All participants underwent baseline and follow-up ocular examinations, including swept-source optical coherence tomography (SS-OCT) and AL measurements. SFCT and CVI were derived from SS-OCT scans using a deep-learning-based program for choroidal structure assessment. The mean age of the participants at baseline was 15.0years (±2.3), with males constituting 47% of the cohort. An inverse relationship was observed between AL elongation and increases in baseline age, baseline SFCT, and CVI, as well as a decrease in baseline AL. Adjusting for other factors, every 10-µm increase in SFCT and each 1% increase in CVI were associated with decreases in AL elongation of 0.007mm (95% confidence interval [CI], -0.013 to -0.002; P = 0.011) and 0.010mm (95% CI, -0.019 to 0.000; P = 0.050), respectively. The incorporation of SFCT or CVI into predictive models improved discrimination over models using only age, gender, and baseline AL (both P < 0.05, likelihood ratio test). Our findings suggest a possible association between a thinner choroid and increased AL elongation over 2 years in children with high myopia, after adjusting for potential baseline risk factors such as age, gender, and initial AL.

Optic Nerve Head Morphology and Macula Ganglion Cell Inner Plexiform Layer Thickness in Axially Anisometropic Rhesus Monkeys.

The purpose of this study was to determine the effects of axial elongation on optic nerve head morphology and macula inner retinal thickness in young rhesus monkeys. Both eyes of 26 anisometropic, 1-year-old rhesus monkeys were imaged using optical coherence tomography (OCT). Before imaging, the animals were sedated, their eyes were dilated, and axial length was measured using an optical biometer. OCT imaging included a 20 degrees, 24-line radial scan centered on the optic nerve head (ONH) and two 20 degrees × 20 degrees raster scans, one centered on the ONH and the other on the macula. Radial scans were analyzed using programs written in MATLAB to quantify the Bruch's membrane opening (BMO) area and position, minimum rim width (MRW), anterior lamina cribrosa surface (ALCS) position, size of any scleral crescent, circumpapillary retinal nerve fiber layer (RNFL), and choroid thickness (pCh). Macula total retinal thickness (mTRT) and ganglion cell inner plexiform layer (GCIPL) thicknesses were quantified from macula scans. Linear least square regression was determined for OCT measures and axial length of the right eye, and for inter-eye differences. Animals were 341 ± 18days old at the time of imaging. BMO area (R2 = 0.38), ALCS position (R2 = 0.45), scleral crescent area (R2 = 0.35), pCh thickness (R2 = 0.21), mTRT (R2 = 0.24), and GCIPL thickness (R2 = 0.16) were correlated with the axial length (all P < 0.05). For each of these parameters, the right-eye regression slope did not differ from the slope of the interocular difference (P > 0.57). There are posterior segment morphological differences in anisometropic rhesus monkeys related to axial length. Whether these differences increase the risk of pathology remains to be investigated.

Detecting Visual Field Worsening From Optic Nerve Head and Macular Optical Coherence Tomography Thickness Measurements.

Compare the use of optic disc and macular optical coherence tomography measurements to predict glaucomatous visual field (VF) worsening. Machine learning and statistical models were trained on 924 eyes (924 patients) with circumpapillary retinal nerve fiber layer (cp-RNFL) or ganglion cell inner plexiform layer (GC-IPL) thickness measurements. The probability of 24-2 VF worsening was predicted using both trend-based and event-based progression definitions of VF worsening. Additionally, the cp-RNFL and GC-IPL predictions were combined to produce a combined prediction. A held-out test set of 617 eyes was used to calculate the area under the curve (AUC) to compare cp-RNFL, GC-IPL, and combined predictions. The AUCs for cp-RNFL, GC-IPL, and combined predictions with the statistical and machine learning models were 0.72, 0.69, 0.73, and 0.78, 0.75, 0.81, respectively, when using trend-based analysis as ground truth. The differences in performance between the cp-RNFL, GC-IPL, and combined predictions were not statistically significant. AUCs were highest in glaucoma suspects using cp-RNFL predictions and highest in moderate/advanced glaucoma using GC-IPL predictions. The AUCs for the statistical and machine learning models were 0.63, 0.68, 0.69, and 0.72, 0.69, 0.73, respectively, when using event-based analysis. AUCs decreased with increasing disease severity for all predictions. cp-RNFL and GC-IPL similarly predicted VF worsening overall, but cp-RNFL performed best in early glaucoma stages and GC-IPL in later stages. Combining both did not enhance detection significantly. cp-RNFL best predicted trend-based 24-2 VF progression in early-stage disease, while GC-IPL best predicted progression in late-stage disease. Combining both features led to minimal improvement in predicting progression.

Retinal optical coherence tomography measures in multiple sclerosis: a systematic review and meta-analysis.

Spectral domain-optical coherence tomography plays a crucial role in the early detection and monitoring of multiple sclerosis (MS) pathophysiology. We aimed to quantify differences in retinal layer measures among different groups of MS and explored different variables that correlate with retinal measures. This study was reported according PRISMA guidelines. A comprehensive search was done across PubMed, Embase, and Google Scholar. The mean difference in thickness of retinal layers and macular volume was assessed. Meta-regression was done to assess the sources of heterogeneity. A total of 100 articles were included in the meta-analyses. The peripapillary retinal nerve fiber layer (pRNFL) thickness significantly decreased in the MSON (MD: -16.44, P < 0.001), MSNON (MD: -6.97, P < 0.001), and PMS (MD: -11.35, P < 0.001) versus HC. The macular RNFL was lower among the MSON (MD: -6.24, P = 0.013) and MSNON (MD: -3.84, P <0.001) versus HC. Macular ganglion cell layer and inner plexiform layer (GCIPL) was thinner among MSON (MD: -14.83, P <0.001), MSNON (MD: -6.38, P < 0.001), and PMS (MD: -11.52, P < 0.001) compared with control eyes. Inner nuclear layer (INL) was higher in the MSON (MD: 0.49, P < 0.001) versus HC. Outer nuclear layer (ONL) thickness significantly lower in the MSNON (MD: -1.15, P = 0.019) versus HC. Meta-regression showed that disease duration, age, EDSS score, and percentage of patients taking DMT are all negatively correlated with pRNFL and GCIPL thickness; however, female gender was correlated with less atrophy. As conclusion, the study highlights substantial thinning in the pRNFL and macular GCIPL between MS versus controls. INL as valuable parameter for capturing inflammatory disease activity.

Can retinal nerve fiber layer (RNFL) thickness be a marker for distinguishing bipolar depression from unipolar depression?

Objective We aimed to compare retinal nerve fiber layer (RNFL) thickness and ganglion cell complex (GCC) thickness in bipolar disorder (BD) and major depressive disorder (MDD). Method The study included thirty MDD, thirty-two BD participants in depressive episode, and thirty-seven controls matched according to age, gender, body mass index (BMI), and smoking status. Optic coherence tomography (OCT) measurements were performed for both participants and controls. The RNFL and GCC thickness were measured and recorded automatically by a spectral OCT device. Participants were also subjected to Hamilton Depression Rating Scale (HAM-D). Results RNFL superior thickness was significantly lower in BD participants, compared to the MDD participants and controls (p = 0.001). GCC inferior (p = 0.022) and inferonasal (p = 0.005) thickness were detected lower in BD group, compared to the control groups. In the BD group, HAM-D scores were negatively correlated with RNFL-temporal (p = 0.049, r= −0.357), GCC inferotemporal (p = 0.02, r= −0.416) and superotemporal thickness (p = 0.002, r= −0.546). Conclusions RNFL thickness were lower in BD participants compared to the MDD and controls and, GCC thickness were lower in BD participants compared to the controls. Our findings support the hypothesis that neurodegeneration is part of the pathogenesis of BD. Future research are needed to confirm the lack of RNFL thickness in MDD, which could have immediate therapeutic consequences as well as implications for distinguishing BD from MDD.

Evaluation of microcirculatory protection in percutaneous revascularisation: A stent implantation technique and device comparison.

Coronary microvascular dysfunction (CMD) after percutaneous coronary intervention (PCI) is prognostically important and may also be a cause of persistent angina. The stent balloon inflation technique or material properties may influence the degree of CMD post-PCI. Thirty-six patients with stable angina attending for elective PCI were randomized to either slow drug eluting stent (DES) implantation technique (DES slow group): +2 atm. every 5 s., maintained for a further 30 s or a standard stent implantation technique (DES std group): rapid inflation and deflation. PressureWire X with thermodilution at rest and hyperemia and optical coherence tomography (OCT) were performed pre- and post-PCI. Combined primary endpoints were changes in index of microvascular resistance (delta IMR) and coronary flow reserve (delta CFR) following PCI. The secondary endpoints included differences in cardiac troponinI (delta cTnI) at 6 hpost-PCI, Seattle angina questionnaire (SAQ) at 1, 3, 6, and 12 months and OCT measures of stent results immediately post-PCI and at 3 months. Both groups were well matched, with similar baseline characteristics and OCT-defined plaque characteristics. Delta IMR was significantly better in the DES slow PCI arm with a median difference of -4.14 (95%CI -10.49, -0.39, p = 0.04). Delta CFR was also numerically higher with a median difference of 0.47 (95% CI -0.52, 1.31, p = 0.46). This did not translate to improved delta median cTnI(1.5 (34.8) vs. 0 (27.5) ng/L, p = 0.75) or median SAQ scoreat 3 months, (85 (20) vs. 95 (17.5), p = 0.47). Slow stent implantation is associated with less CMD after elective PCI in patients with stable angina.

Values of peripapillary retinal nerve fibre layer thickness are different in children and adults

ABSTRACT Clinical relevance The detection of abnormal values of peripapillary nerve fibre layer (pRNFL) thickness measured with optical coherence tomography (OCT) is important for detecting optic nerve disease in children. Background To evaluate the level of agreement between the adult reference database supplied with an OCT device and the present paediatric study database for the measurement of pRNFL thickness in children. This study also aimed to provide reference values for pRNFL thickness according to the spherical equivalent in the paediatric population. Methods This was a cross-sectional study. One hundred and twenty-six healthy children were included, who had undergone a full ophthalmological examination including cycloplegic refraction and examination of pRNFL thickness using the Topcon 3D OCT 2000 device (Topcon Corporation, Tokyo, Japan). Values equal to or below the fifth percentile (≤p5) and above the 95th percentile (>p95) were considered abnormal. Observed agreement and specific agreement were investigated between OCT measurements classified with paediatric and adult reference values for normality. Results Values ≤ p5 in the adult database were recorded for 2 of the 30 values (6.6%) of the pRNFL values by quadrants ≤p5 in the paediatric database and 17 of the 88 (19.3%) values by sectors ≤p5. For values >p95 in the adult database, 88% by quadrants and 72% by sectors would have been classified as being within the normal range using the paediatric database. Conclusion The use of adult reference values currently available in OCT devices can lead to classification errors concerning the normal range of pRNFL thickness in a large proportion of paediatric patients. The use of normative paediatric databases, such as the one discussed in this study, should be taken into consideration.

Revealing Subsurface Damage Morphology and Patterns in areal Ultrashort Pulse Laser Machining of Glass

Material removal rates as well as surface and subsurface quality are key aspects for the industrial application of ultrashort pulse (USP) laser machining. However, revealing so-called subsurface damage (SSD) is challenging. The presented study visualizes and quantifies subsurface damage patterns in areal USP laser ablation of fused silica (FS) and glass N-BK7 (BK). For the first time, using high-resolution optical coherence tomography (OCT) as non-destructive and three-dimensional (3D) evaluation method, SSD morphologies of areal laser machining induced damages are analysed. Influences of laser wavelength, beam geometry and processed material are investigated. Discovered differences of damage morphologies and depth in FS and BK point out the relevance of selecting suitable process parameters. Based on the evaluation of volumetric OCT data, the authors were able to quantify damage morphologies using the surface texture ratio as well as power spectral density functions. One important finding for the quantification and comparability of damage depths in USP laser processing is the influence of applicable evaluation thresholds. In comparison to area thresholds of 0.001% being applicable to OCT measurements, more lenient thresholds of e.g. 1% commonly applied in destructive SSD measurement methods in average result in a reduction of measured damage depths by a factor of ~ 2. This potentially leads to an underestimation of damage depths depending on methods on thresholds used. The presented measurement and evaluation methods as well as gained process insights are important assets for the future optimization of low-damage USP laser micromachining of brittle materials. Moreover, the general applicability and relevance of OCT-based morphological damage analysis in laser material processing is shown.

Polarization-resolved analysis of outer retinal bands: investigating ballistic and multiply scattered photons using full-field swept-source optical coherence tomography.

Precise interpretation of the anatomical origins of outer retinal optical coherence tomography (OCT) presents technical challenges owing to the delicate nature of the retina. To address this challenge, our study introduces a novel polarization-sensitive full-field swept-source OCT (FF-SS-OCT) that provides parallel-polarization and cross-polarization OCT measurements, predominantly capturing ballistically reflected photons and multiply scattered photons, respectively. Notably, parallel-polarization OCT unveils layer-like structures more effectively, including the inner plexiform layer (IPL) sub-layers, outer plexiform layer (OPL) sub-layers (in rod-dominant regions), and rod/cone outer segment (OS) tips, compared to cross-polarization OCT, where such sub-layers are not visible. Through a comparative analysis of parallel-polarization and cross-polarization OCT images of the outer retina, we discovered that the 2nd outer retinal OCT band results from contributions from both the ellipsoid zone (EZ) and the inner segment/outer segment (IS/OS) junction. Similarly, the 3rd outer retinal OCT band appears to reflect contributions from both the interdigitation zone (IZ) and photoreceptor OS tips. This polarization-sensitive approach advances our understanding of the origins of outer retinal OCT signals and proposes potential new biomarkers for assessing retinal health and diseases.

Insights into atypical segmental layer thicknesses and phase retardation in thick corneas using ultrahigh-resolution polarization-sensitive optical coherence tomography

BackgroundAccurately assessing corneal structural status is challenging when thickness deviates from the average. Polarization-sensitive optical coherence tomography (PS-OCT) measures tissue-specific polarization changes, providing additional contrast for accurate segmentations and aids in phase retardation (PR) measurements. Previous studies have shown PR's effectiveness in identifying sub-clinical keratoconus (KC) in asymmetric cases. Thus, this study aims to assess PR distribution in thick corneas with and without KC.MethodsIn this retrospective and cross-sectional study, 45 thick corneas from 30 Asian-Indian subjects, categorized into healthy (n = 26) and KC (n = 19) groups were analyzed. All eyes underwent standard clinical evaluations, tomographic assessments, and corneal biomechanics measurements. PR and individual layer thicknesses were measured using custom-designed ultrahigh-resolution PS-OCT. PR en-face maps were generated. Individual layer thicknesses and PR analysis was conducted across multiple zones, extending up to 8–10 mm in diameter. All eyes in the study had not undergone interventions, received topical medications, or had previous corneal disease history.ResultsSignificant differences were found in spherical and cylindrical powers, keratometry, pachymetry, and biomechanical indices (all P < 0.01). Thickness profiles from PS-OCT showed significant differences in the 4–8 mm zones only. Bowman's layer thickness significantly differed only in the central 2 mm zone (P = 0.02). The median PR values showed marginal differences in the central 2 mm zone (P = 0.0565). Additionally, there were significant differences observed in the 2–4 mm and 4–6 mm zones (P = 0.0274 and P = 0.0456, respectively). KC eyes exhibited an atypical PR distribution and corneal thinning, while normal eyes maintained a uniform Bowman’s layer thickness and PR maps with larger areas of higher PR.ConclusionThe study revealed distinctive PR distribution in thick corneas among healthy and KC groups. Using an ultrahigh-resolution PS-OCT the significance of Bowman's layer thickness in these groups was also emphasized. The study offered potential improvements in clinical diagnostics by enhancing our understanding of corneal structure and its altered function.