Domain Optical Coherence Tomography Scans Research Articles

Risk factors for diabetic retinopathy, diabetic macular edema, and sight-threatening diabetic retinopathy

ObjectiveTo identify the risk factors for the development of diabetic retinopathy (DR), diabetic macular edema (DME), and sight-threatening DR (STDR) based on a city-wide diabetes screening program. Research design and methodsDiabetic patients were prospectively recruited between June 2016 and December 2022. All patients underwent dilated fundus photography centered on the disc and macula or macular spectral domain optical coherence tomography (SD-OCT) scan. Complete medical history was documented. Systematic examination, blood analysis, and urinalysis were performed. Multivariate logistic regression analysis adjusting for age and sex was conducted. ResultsOut of 7274 diabetic patients, 6840 had gradable images, among which 3054 (42.0%) were graded as DR, 1153 (15.9%) as DME, and 1500 (20.6%) as STDR. The factors associated with DR, DME, and STDR included younger age (odds ratio [OR]: 0.96, 0.97, and 0.96 respectively), lower BMI (OR: 0.97, 0.95, and 0.95 respectively), longer duration of diabetes (OR: 1.07, 1.03, and 1.05 respectively) and positive of urinary albumin (OR: 2.22, 2.56, and 2.88 respectively). Other associated factors included elevated blood urea nitrogen (OR: 1.22, 1.28, and 1.27 respectively), higher LDL-cholesterol, lower blood hemoglobin (OR: 0.98, 0.98, and 0.98), insulin intake, presence of diabetic foot pathologies and diabetic peripheral neuropathy. We also identified novel risk factors, including high serum potassium (OR: 1.37, 1.46, and 1.55 respectively), high-serum sodium (OR: 1.02, 1.02, and 1.04 respectively). Better family income was a protective factor for DR, DME, and STDR. Alcohol consumption once a week was also identified as a protective factor for DR. ConclusionsSimilar risk factors for DR, DME, and STDR were found in this study. Our data also indicates high serum sodium, high serum potassium, low blood hemoglobin, and level of family income as novel associated factors for DR, DME, and STDR, which can help with DR monitoring and management.

Compartmental Exudative Dynamics in Neovascular Age-Related Macular Degeneration: Volumetric Outcomes and Impact of Volatility in a Phase III Clinical Trial

PurposeTo examine retinal feature dynamics in eyes with neovascular age-related macular degeneration (nAMD) treated with anti-vascular endothelial growth factor (anti-VEGF) therapy and the relationship of these features with visual acuity. DesignPost hoc analysis of the phase 3, randomized, HAWK nAMD clinical trial. ParticipantsParticipants randomized to the brolucizumab 6 mg or aflibercept 2 mg arms of the trial. MethodsSpectral domain optical coherence tomography (OCT) scans collected at 4-week intervals were analyzed using an automated machine learning-enhanced segmentation and feature-extraction platform with manual verification. Quantitative volumetric measures of retinal and exudative features were exported at multiple timepoints over 48 weeks. Volatility of exudative features was calculated as the standard deviation of each feature value during the maintenance phase (week 12–48) of treatment. These features were examined for their associations with anatomic and functional outcomes. Main Outcome MeasuresLongitudinal intraretinal fluid (IRF) and subretinal fluid (SRF) volume, subretinal hyperreflective material (SHRM) volume, ellipsoid zone (EZ) integrity (EZ-retinal pigment epithelium [RPE] volume/thickness), and correlation with best corrected visual acuity (BCVA). ResultsIRF, SRF, and SHRM demonstrated significant volumetric reduction from baseline with anti-VEGF therapy (P<0.001 at each timepoint). EZ integrity measures demonstrated significant improvement from baseline (P<0.001 at each timepoint). Both EZ integrity and SHRM measures significantly correlated with BCVA at all timepoints (EZ-RPE volume: 0.38≤ r ≤0.47; EZ-RPE central subfield thickness: 0.22≤ r ≤0.41; SHRM volume: -0.33≤ r ≤-0.44). Following treatment initiation, correlations of IRF and SRF volume with BCVA were weak or nonsignificant. Eyes with lower volatility of IRF, SRF, and SHRM volumes during the maintenance phase showed greater improvements in EZ integrity (all P<0.01) and greater gains in BCVA (all P<0.01) at week 48 compared to eyes with higher volatility in those exudative parameters. ConclusionsQuantitative measures of SHRM volume and EZ integrity correlated more strongly with BCVA than retinal fluid volumes during treatment. High volatility of exudative parameters, including SRF, during the maintenance phase of treatment was associated with loss of EZ integrity and BCVA.

Autologous internal limiting membrane transplantation achieves anatomic closure and functional improvement in the treatment of large, persistent macular holes

PurposeTo evaluate the clinical outcome of subretinal autologous internal limiting membrane (ILM) transplantation during pars-plana vitrectomy for persistent full-thickness macular hole (FTMH) repair.MethodsRetrospective, consecutive case series of 13 eyes (13 patients) undergoing small-incision vitrectomy with ILM transplantation and air tamponade for large persistent FTMH after prior unsuccessful vitrectomy with posterior hyaloid detachment and ILM peeling.Main outcome measurementsFor all eyes, high-definition spectral domain optical coherence tomography scans (SD-OCT Spectralis, Heidelberg Engineering GmbH, Germany) of the macula were routinely performed before surgery, 1 and 4 weeks after surgery, and at the final follow-up visit. Additionally, age, gender, axial length, macular hole diameter, biomicroscopic fundus evaluation and best‐corrected visual acuity (BCVA) at baseline, 1 and 4 weeks after surgery, and at the final follow-up visit were analyzed.ResultsAnatomic closure was achieved in all 13 cases (100% success rate). Closure pattern was classified in accordance with to Rossi et al. (Graefe’s Arch Clin Exp Ophthalmol 258(12):2629–2638, 2020). Mean baseline BCVA logMAR was 0.93, mean postoperative BCVA logMAR was 0.66 with a mean postoperative follow-up period of 11.4 months. No re-opening occurred during the observation period.ConclusionsPlacing an autologous ILM-transplant in the subretinal space beneath the margin of the FTMH can support anatomic restauration and functional improvement in large, persistent FTMHs.

Retinal Ischemic Perivascular Lesions in Individuals With Atrial Fibrillation.

Background We previously demonstrated that retinal ischemic perivascular lesions (RIPLs), which are indicative of ischemia in the middle retina, may be a biomarker of ischemic cardiovascular disease. In this study, we sought to determine the relationship between RIPLs and atrial fibrillation, a common source of cardiac emboli. Methods and Results In this case-control study, we identified individuals between the ages of 50 and 90 years who had undergone macular spectral domain optical coherence tomography imaging. Individuals with atrial fibrillation were identified, and age- and sex-matched individuals from the same pool, but without a diagnosis of atrial fibrillation, were selected as controls. Spectral domain optical coherence tomography scans were reviewed by 3 independent and masked observers for presence of RIPLs. The relationship between RIPLs and atrial fibrillation was analyzed using multivariable logistic regression models. There were 106 and 91 subjects with and without atrial fibrillation, respectively. The percentage of subjects with RIPLs was higher in the atrial fibrillation group compared with the control group (57.5% versus 37.4%; P=0.005). After adjusting for age, sex, smoking history, hypertension, diabetes, coronary artery disease, carotid stenosis, stroke, and myocardial infarction, the presence of RIPLs was significantly associated with atrial fibrillation, with an odds ratio of 1.91 (95% CI, 1.01-3.59). Conclusions RIPLs are significantly associated with atrial fibrillation, independent of underlying ischemic heart disease or cardiovascular risk factors. This association may inform the diagnostic cardiovascular workup for individuals with RIPLs incidentally detected on optical coherence tomography scan of the macula.

Retinal Neurodegeneration as a Potential Biomarker of Accelerated Aging in Schizophrenia Spectrum Disorders.

Several biological markers are believed to reflect accelerated aging in schizophrenia spectrum disorders; however, retinal neural changes have not yet been explored as potential CNS biomarkers of accelerated aging in this population. The aim of this study was to determine whether retinal neural layer thinning is more strongly related to age in schizophrenia and schizoaffective disorder patients (SZ) than in a psychiatrically healthy control group (CON). Schizophrenia (n = 60) and CON participants (n = 69) underwent spectral domain optical coherence tomography (OCT) scans to examine the following variables in both eyes: retinal nerve fiber layer (RNFL) thickness, macula central subfield (CSF) thickness, macula volume, ganglion cell layer-inner plexiform layer (GCL-IPL) thickness, optic cup volume, and cup-to-disc ratio. Eleven participants in each group had diabetes or hypertension. Significant negative relationships between age and RNFL thickness, macula volume, and GCL-IPL thickness were observed in the SZ group, while no significant relationships were observed in the CON group. However, many of the findings in the SZ group lost significance when participants with diabetes/hypertension were removed from analyses. A notable exception to this was that the age × SZ interaction accounted for a unique proportion of variance in GCL-IPL thinning over and above the effect of diabetes/hypertension. The results suggest that retinal atrophy occurs at an increased rate in schizophrenia spectrum disorders, potentially reflecting accelerated aging inherent to these conditions, with considerable contributions from systemic medical diseases closely linked to this population.

Hyper-reflective dots in optical coherence tomography imaging and inflammation markers in diabetic retinopathy.

The aim of this study is to correlate small dot hyper-reflective foci (HRF) observed in spectral domain optical coherence tomography (SD-OCT) scans of an animal model of hyperglycaemia with focal electroretinography (fERG) response and immunolabelling of retinal markers. The eyes of an animal model of hyperglycaemia showing signs of diabetic retinopathy (DR) were imaged using SD-OCT. Areas showing dot HRF were further evaluated using fERG. Retinal areas enclosing the HRF were dissected and serially sectioned, stained and labelled for glial fibrillary acidic protein (GFAP) and a microglial marker (Iba-1). Small dot HRF were frequently seen in OCT scans in all retinal quadrants in the inner nuclear layer or outer nuclear layer in the DR rat model. Retinal function in the HRF and adjacent areas was reduced compared with normal control rats. Microglial activation was detected by Iba-1 labelling and retinal stress identified by GFAP expression in Müller cells observed in discrete areas around small dot HRF. Small dot HRF seen in OCT images of the retina are associated with a local microglial response. This study provides the first evidence of dot HRF correlating with microglial activation, which may allow clinicians to better evaluate the microglia-mediated inflammatory component of progressive diseases showing HRF.

Choroidal lesions in varicella zoster virus uveitis

To evaluate choroidal lesions with spectral domain optical coherence tomography (SD-OCT) scan in varicella zoster virus (VZV) uveitis.VZV-uveitis cases which underwent OCT scan for choroidal lesions were studied. SD-OCT scan passing through these lesions was studied in detail. Subfoveal choroidal thickness (SFCT) during active and resolved stages was studied. Angiogaphic features were studied where available.Thirteen out of 15 cases had same-sided herpes zoster ophthalmicus skin rashes. All except three patients had old or active kerato-uveitis. All eyes demonstrated clear vitreous and a single or multiple hypopigmented orangish-yellow choroidal lesions. The number of lesions remained unchanged during the follow-up on clinical examination. SD-OCT over lesions (n = 11) showed choroidal thinning (n = 5), hyporeflective choroidal elevation during active inflammation (n = 3), transmission effects (n = 4), and ellipsoid zone disruption (n = 7). The mean change in SFCT (n = 9) after resolution of the inflammation was 26.3 μm (range: 3-90 μm). Fundus fluorescein angiography showed iso-fluorescence over lesions in all (n = 5), but indocyanine green angiography (n = 3) showed hypofluorescence at lesions. Mean follow-up was 1.38 years (range: 3 months-7 years). De-novo appearance of choroidal lesion during the first relapse of VZV-uveitis was captured in one case.VZV-uveitis can cause focal or multifocal hypopigmented choroidal lesions with thickening or scarring of choroidal tissue, depending on the disease activity.

Bacillary layer detachment with malignant choroidal tumors: a case series

PurposeTo study the incidence and characteristics of bacillary layer detachment (BALAD) occurring with the two most common choroidal malignancies, choroidal metastasis and choroidal melanoma.MethodsA retrospective multicentric record analysis. Eyes with a diagnosis of choroidal melanoma or choroidal metastasis that had good-quality fundus photography and spectral domain optical coherence tomography (OCT) scans of the macular and tumor regions allowing for delineation of the retinal layers were included for analysis. Qualitative image evaluation was done by two independent graders for the presence, location, and OCT features of BALAD, as well as any associated intraretinal or subretinal fluid. Demographic and clinical data were also retrieved.ResultsOf the 11 eyes with choroidal metastasis and 7 eyes with choroidal melanoma that were included in the final analysis, 6 (54.5%) and 1 (14.3%) had BALAD, respectively. The BALAD co-localized with the subretinal fluid in all cases and with the intraretinal fluid in 1/3 cases (33.3%), was foveal in location in 3 eyes (42.9%), was overlying the tumor in 6 eyes (85.7%), and varied in number and size. Reflectivity within the BALAD was consistently higher than the vitreous and adjacent subretinal fluid, and discernable suspended hyperreflective particles were noted in 5 eyes (71.4%).ConclusionBALAD is relatively common with choroidal metastasis. The OCT features described supplement our recognition of this new entity.

Correction of Retinal Nerve Fiber Layer Thickness Measurement on Spectral-Domain Optical Coherence Tomographic Images Using U-net Architecture.

In this study, an algorithm based on deep learning was presented to reduce the retinal nerve fiber layer (RNFL) segmentation errors in spectral domain optical coherence tomography (SD-OCT) scans using ophthalmologists' manual segmentation as a reference standard. In this study, we developed an image segmentation network based on deep learning to automatically identify the RNFL thickness from B-scans obtained with SD-OCT. The scans were collected from Farabi Eye Hospital (500 B-scans were used for training, while 50 were used for testing). To remove the speckle noise from the images, preprocessing was applied before training, and postprocessing was performed to fill any discontinuities that might exist. Afterward, output masks were analyzed for their average thickness. Finally, the calculation of mean absolute error between predicted and ground truth RNFL thickness was performed. Based on the testing database, SD-OCT segmentation had an average dice similarity coefficient of 0.91, and thickness estimation had a mean absolute error of 2.23 2.1 μm. As compared to conventional OCT software algorithms, deep learning predictions were better correlated with the best available estimate during the test period (r2 = 0.99 vs r2 = 0.88, respectively; P 0.001). Our experimental results demonstrate effective and precise segmentation of the RNFL layer with the coefficient of 0.91 and reliable thickness prediction with MAE 2.23 2.1 μm in SD-OCT B-scans. Performance is comparable with human annotation of the RNFL layer and other algorithms according to the correlation coefficient of 0.99 and 0.88, respectively, while artifacts and errors are evident.

Choroidal vascularity index in hydroxychloroquine toxic retinopathy: a quantitative comparative analysis using enhanced depth imaging in spectral domain optical coherence tomography.

To investigate choroidal involvement in eyes of patients treated with hydroxychloroquine (HCQ), by quantifying the choroidal vascularization index (CVI) and other choroidal biomarkers. Vertical Enhanced Depth Imaging spectral domain Optical Coherence Tomography (SD-OCT) scans were performed in eyes with either advanced stage or mild HCQ toxic retinopathy, as well as in healthy age and sex-matched controls. Based on SD-OCT scans, the sub foveal and mean choroidal thickness (ChT) were measured. The CVI, total choroidal area (TCA), luminal choroidal area (LCA) and stromal choroidal area (SCA) were calculated based on a binarization image process. These variables were computed and compared between the three groups (i.e., advanced stage, mild toxicity and healthy controls). Forty-eight eyes of 47 patients under HCQ (26 eyes presented with advanced stage HCQ toxicity, 22 eyes with mild toxicity) and thirty-four eyes of 31 healthy controls were included. Both CVI and ChT were significantly different between the three groups (p < 0.001, p< 0.001). When comparing the advanced stage toxicity group to healthy controls, both the subfoveal and the mean ChT were diminished (p < 0.001). The CVI, TCA, LCA, SCA were significantly lower in the advanced stage of toxicity group when compared to controls (p <0.001, < 0.00001, <0.0001, p= 0.0094 respectively). Our study suggests that eyes with HCQ toxic retinopathy, especially at advanced stages, present with choroidal impairment, giving further pathophysiological insights into the unfolding of this retinal toxicity.

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.

Investigation of Structural Alterations in Inherited Retinal Diseases: A Quantitative SD-OCT-Analysis of Retinal Layer Thicknesses in Light of Underlying Genetic Mutations.

Inherited retinal diseases can result from various genetic defects and are one of the leading causes for blindness in the working-age population. The present study aims to provide a comprehensive description of changes in retinal structure associated with phenotypic disease entities and underlying genetic mutations. Full macular spectral domain optical coherence tomography scans were obtained and manually segmented in 16 patients with retinitis pigmentosa, 7 patients with cone−rod dystrophy, and 7 patients with Stargardt disease, as well as 23 age- and sex-matched controls without retinal disease, to assess retinal layer thicknesses. As indicated by generalized least squares models, all IRDs were associated with retinal thinning (p < 0.001), especially of the outer nuclear layer (ONL, p < 0.001). Except for the retinal nerve fiber layer, such thinning was associated with a reduced visual acuity (p < 0.001). These advances in our understanding of ultrastructural retinal changes are important for the development of gene-, cell-, and optogenetic therapy. Longitudinal studies are warranted to describe the temporal component of those changes.

Retinal Layer Thinning After Optic Neuritis Is Associated With Future Relapse Remission in Relapsing Multiple Sclerosis.

Remission of relapses is an important contributor to both short- and long-term prognosis in relapsing multiple sclerosis (RMS). In MS-associated acute optic neuritis (MS-ON), retinal layer thinning measured by optical coherence tomography (OCT) is a reliable biomarker of both functional recovery and the degree of neuroaxonal damage. However, prediction of non-ON relapse remission is challenging. We aimed to investigate whether retinal thinning after ON is associated with relapse remission after subsequent non-ON relapses. For this longitudinal observational study from the Vienna MS database, we included patients with MS with (1) an episode of acute ON, (2) available spectral domain OCT scans within 12 months before ON onset (OCTbaseline), within 1 week after ON onset (OCTacute), and 3-6 months after ON (OCTfollow-up), and (3) at least 1 non-ON relapse after the ON episode. Subsequent non-ON relapses were classified as displaying either complete or incomplete remission based on change in the Expanded Disability Status Scale score assessed 6 months after relapse. Association of retinal thinning in the peripapillary retinal nerve fiber layer (ΔpRNFL) and macular ganglion cell and inner plexiform layer (ΔGCIPL) with incomplete remission was tested by multivariate logistic regression models adjusting for age, sex, disease duration, relapse severity, time to steroid treatment, and disease-modifying treatment status. We analyzed 167 patients with MS (mean age 36.5 years [SD 12.3], 71.3% women, mean disease duration 3.1 years [SD 4.5]) during a mean observation period of 3.4 years (SD 2.8) after the ON episode. In 61 patients (36.5%), at least 1 relapse showed incomplete remission. In the multivariable analyses, incomplete remission of non-ON relapse was associated with ΔGCIPL thinning both from OCTbaseline to OCTfollow-up and from OCTacute to OCTfollow-up (OR 2.4 per 5 μm, p < 0.001, respectively), independently explaining 29% and 27% of variance, respectively. ΔpRNFL was also associated with incomplete relapse remission when measured from OCTbaseline to OCTfollow-up (OR 1.9 per 10 μm, p < 0.001), independently accounting for 22% of variance, but not when measured from OCTacute to OCTfollow-up. DISCUSSION: Retinal layer thinning after optic neuritis may be useful as a marker of future relapse remission in RMS.

The correlation of atrophy, traction and neovascularization in myopic choroidal neovascularization according to a novel myopic maculopathy classification system (atrophy (A), traction (T), neovascularization (N): ATN).

To grade myopic choroidal neovascularization (CNV) patients according to the new myopic maculopathy classification (A: atrophy, T: traction, N: neovascularization-ATN) and analyze the correlation in between atrophy, traction and neovascularization. Fifty-one eyes of 41 patients with the diagnosis of pathologic myopia and myopic CNV were included in this clinical practice study. Patients were graded according to the recently described ATN classification. Color fundus photographs were used to grade the atrophy and spectral domain optical coherence tomography scans were used to grade traction and neovascularization. Active myopic CNVs were treated with intravitreal anti-vascular endothelial growth factor (VEGF) injections. Chi-square test was used to test the categorical variants and univariate logisticregression analysis was used to predict the independent risk factorsof myopic CNV scar formation. Active myopic CNV was observed most frequently in the group with patchy chorioretinal atrophy. Grade of the atrophy and female gender were significantly associated with myopic CNV scar in the univariate logistic regression tests. Multivariate logistic regression showed that atrophy grading is the independent predictor of myopic CNV scar. ATN classification is a practical and comprehensive system to grade myopic CNV. Atrophy is an independent predictor for myopic CNV scar and patchy chorioretinal atrophy requires a more careful examination and close follow-up for the risk of CNV development.

The use of optical coherence tomography for skin evaluation in healthy rats.

Noninvasive diagnostic techniques allow for morphological and morphometric in vivo evaluation of the skin. Optical coherence tomography (OCT) is a method that allows visualization of dermal structures up to several 100 μm with a resolution of 3-7.5 μm. The aim of the study was the morphological and morphometric assessment of rats' skin using SD-OCT. Fifteen male Wistar rats, aged 3 and 8 months, weighing 350-450 g. The skin of the plantar metatarsal area of the right pelvic limb was assessed. The measurements were performed using Spectral Domain Optical Coherence Tomography (SD-OCT) scans and histological images. Spectral Domain Optical Coherence Tomography could determine the boundary between the epidermis and the dermis. Apart from the stratum corneum (SC), it did not allow for the differentiation of the individual epidermal layers. In the SD-OCT and in the histological examination, the mean thicknesses of the layers (μm ± SD) were (respectively): SC 33.053 ± μm(SD 5.85, 29.675 ± 5.54; epidermis 88.2 ± 7.97, 65.126 ± 13.23; dermis 259.86 ± 18.29, 166.05 ± 31.88 μm. There was a correlation between the total epidermal SD-OCT and histological measurements (r= 0.43, p= 0.05). Bland-Altman plots revealed a bias of -19.18 (95% confidence interval) -39.21 to 0.84 μm) in the case of live epidermis (stratum granulosum, stratum spinous, stratum basale). Spectral Domain Optical Coherence Tomography can be used to evaluate rat epidermis and dermis. The method enables the differentiation of the SC, as well as the epidermis and the dermis. SD-OCT and histological thickness dimensions of the epidermis and skin differ.

Evaluation of macular function and morphology following accelerated collagen cross-linking in progressive keratoconus.

To assess any changes in macular function and morphology in patients with progressive keratoconus undergoing accelerated corneal cross-linking (CXL). This prospective case series included 9 eyes of 8 patients with progressive keratoconus undergoing CXL using a high intensity accelerated protocol (9 mW/cm2 for 14 min) with a total surface dose of 7.5 J/cm2. Visual acuity assessment, slit lamp biomicroscopy, dilated fundoscopy, corneal tomography, multifocal electroretinography (mfERG) and spectral domain optical coherence tomography scan were performed at baseline, 2 weeks and 6 weeks postoperatively. Uncorrected and corrected distance visual acuity did not change significantly at 2 weeks and 6 weeks following accelerated CXL compared to baseline. Retinal response density (RRD) of mfERG significantly decreased at 2 weeks postoperatively compared to baseline (p = 0.008) but did not differ from the baseline value at 6 weeks postoperatively in the fovea (ring 1) (p = 0.95). Similarly, P1 latency significantly decreased at 2 weeks (p = 0.04) but did not change at 6 weeks (p = 1.00) postoperatively compared to baseline in the fovea. No changes in RRD or P1 latency were observed in the retinal rings surrounding the fovea (rings 2 to 5). Central foveal thickness did not change at 2 weeks and 6 weeks postoperatively compared to baseline (p = 0.53 and p = 0.93, respectively). A short-term reversible decrease in macular electrical activity without any structural changes seems to occur after accelerated CXL in patients with progressive keratoconus. The return of macular response to the preoperative values shows the safety of the CXL protocol.

A Robust Microbead Occlusion Model of Glaucoma for the Common Marmoset.

PurposeTo establish a robust experimental model of glaucoma in the common marmoset (Callithrix jacchus), a New World primate, using an intracameral microbead injection technique.MethodsElevated intraocular pressure (IOP) was induced by an injection of polystyrene microbeads. Morphologic changes in the retina and optic nerve of glaucomatous eyes were assessed and electroretinogram (ERG) recordings were performed to evaluate functional changes.ResultsMicrobead injections induced a sustained IOP elevation for at least 10 weeks in a reproducible manner. At the end of the 10-week experimental period, there was significant loss of retinal ganglion cells (RGCs) in all quadrants and eccentricities, although it was more prominent in the mid-peripheral and peripheral regions. This was consistent with a thinning of the Retinal nerve fiber layer (RNFL) seen in spectral domain optical coherence tomography scans. Surviving RGCs showed marked changes in morphology, including somatic shrinkage and dendritic atrophy. Retinas also showed significant gliosis. The amplitude of the ERG photopic negative response, with subsequent a- and b-wave changes, was reduced in glaucomatous eyes. The optic nerve of glaucomatous eyes showed expanded cupping, disorganization of the astrocytic matrix, axonal loss, and gliosis.ConclusionsWe developed a robust and reproducible model of glaucoma in the marmoset. The model exhibits both structural and functional alterations of retina and optic nerve characteristic of glaucoma in humans and animal models.Translational RelevanceThe glaucoma model in the marmoset described here forms a robust method to study the disease etiology, progression, and potential therapies in a nonhuman primate, allowing for more effective translation of animal data to humans.

Measurement of Myopia and Normal Human Choroidal Thickness Using Spectral Domain Optical Coherence Tomography

Myopia is a common ophthalmic deficiency. The structure and function of choroid layer is assumed to be associated with myopia. In this study, a laboratory developed spectral domain optical coherence tomography scanning system is used to image human eyes. The axial resolution of the system is about 7 μm, and the acquisition rate is 100 kHz. Firstly, a cross-sectional image was acquired by averaging 100 images from imaging posterior segment of each eye. The choroid thickness was measured by 11 discrete points. The average thickness of normal human eyes was (0.296 ± 0.126) mm, whereas the average choroid thickness of myopic eyes was (0.220 ± 0.095) mm. Afterwards, the T test is used to calculate the data statistically. The analysis of the final result is based on the average thickness measured and the thickness of each measuring point. There was a significant difference in choroid thickness between myopia and normal eyes (P value < 0.01), which indicates that the choroid thickness of myopia was significantly thinner than that of normal eyes. Besides, there are findings that the choroidal thickness in nasal side is thinner than that in the fovea and temporal side in each eye. The choroidal thickness on temporal side in myopia eye has the most significant difference comparing with that in normal eye. The comprehensive evaluation of myopia and normal choroidal thickness using spectral domain optical coherence tomography may provide an important reference for the development of medical methods for diagnosis and treatment of myopia.

Benchmarking automated detection of the retinal external limiting membrane in a 3D spectral domain optical coherence tomography image dataset of full thickness macular holes

In this article, we present a new benchmark for the segmentation of the retinal external limiting membrane (ELM) using an image dataset of spectral domain optical coherence tomography (OCT) scans in a patient population with idiopathic full-thickness macular holes. Specifically, the dataset used contains OCT images from one eye of 107 patients with an idiopathic full-thickness macular hole. In total, the dataset contains 5243 individual 2-dimensional (2-D) OCT image slices, with each patient contributing 49 individual spectral-domain OCT tagged image slices. We display precise image-wise binary annotations to segment the ELM line. The OCT images present high variations in image contrast, motion, brightness, and speckle noise which can affect the robustness of applied algorithms, so we performed an extensive OCT imaging and annotation data quality analysis. Imaging data quality control included noise, blurriness and contrast scores, motion estimation, darkness and average pixel scores, and anomaly detection. Annotation quality was measured using gradient mapping of ELM line annotation confidence, and idiopathic full-thickness macular hole detection. Finally, we compared qualitative and quantitative results with seven state-of-the-art machine learning-based segmentation methods to identify the ELM line with an automated system.

Enhanced Objective Detection of Retinal Nerve Fiber Bundle Defects in Glaucoma With a Novel Method for En Face OCT Slab Image Construction and Analysis.

PurposeTo introduce and evaluate the performance in detecting glaucomatous abnormalities of a novel method for extracting en face slab images (SMAS), which considers varying individual anatomy and configuration of retinal nerve fiber bundles.MethodsDense central retinal spectral domain optical coherence tomography scans were acquired in 16 participants with glaucoma and 19 age-similar controls. Slab images were generated by averaging reflectivity over different depths below the inner limiting membrane according to several methods. SMAS considered multiple 16 µm thick slabs from 8 to 116 µm below the inner limiting membrane, whereas 5 alternative methods considered single summary slabs of various thicknesses and depths. Superpixels in eyes with glaucoma were considered abnormal if below the first percentile of distributions fitted to control data for each method. The ability to detect glaucoma defects was measured by the proportion of abnormal superpixels. Proportion of superpixels below the fitted first percentile in controls was used as a surrogate false-positive rate. The effects of slab methods on performance measures were evaluated with linear mixed models.ResultsThe ability to detect glaucoma defects varied between slab methods, χ2(5) = 120.9, P < 0.0001, with SMAS showing proportion of abnormal superpixels 0.05 to 0.09 greater than alternatives (all P < 0.0001). No slab method found abnormal superpixels in controls.ConclusionsSMAS outperformed alternatives in detecting abnormalities in eyes with glaucoma. SMAS evaluates all depths with potential retinal nerve fiber bundle presence by combining multiple slabs, resulting in greater detection of reflectance abnormalities with no increase in surrogate false positives.Translational RelevanceSMAS may be used to objectively detect glaucoma defects in en face optical coherence tomography images.