Optical Coherence Tomography Retinal Thickness Research Articles

Use of optical coherence tomography retinal thickness deviation map for hydroxychloroquine retinopathy screening

Background: Hydroxychloroquine (HCQS) is widely used to treat several rheumatic and skin diseases and can cause damage to the outer retina, known as HCQS retinopathy, and is common among long-term users of the drug with higher daily dose by weight. The goal of screening for retinopathy is to recognize signs of toxicity at an early enough stage to prevent the loss of visual acuity. Aims and Objectives: This study aimed to evaluate the diagnostic performance of a commercially available retinal thickness deviation map obtained by spectral-domain (SD) optical coherence tomography (OCT) for screening of HCQS retinopathy. Materials and Methods: This study was a prospective comparative study between unaffected (patients who did not develop retina toxicity) and affected (who developed toxicity) of 50 patients of the age group of 14–60 years taking HCQS medication for several dermatological and rheumatologic disorders. The patients who fulfilled the inclusion criteria were screened for HCQS retinal toxicity using SD-OCT, standard automated perimetry, fundus autofluorescence, and comprehensive ophthalmic examinations. Results: In this study, in group 2 patients, 60% were having parafoveal, 30% having perifoveal, and 10% having a mixed pattern (P<0.001) of HCQS retinopathy, and the mean deviation and pattern standard deviation increase as the severity of disease increases (P<0.005). Conclusion: This study concluded that HCQS is a safer drug and can be used safely in these patients with proper HCQS retinal toxicity monitoring with an SD-OCT-generated retinal thickness deviation map and with regular follow-up to monitor reduced thickness in the parafoveal region.

Derivation of human retinal cell densities using high-density, spatially localized optical coherence tomography data from the human retina.

This study sought to identify demographic variations in retinal thickness measurements from optical coherence tomography (OCT), to enable the calculation of cell density parameters across the neural layers of the healthy human macula. From macular OCTs (n=247), ganglion cell (GCL), inner nuclear (INL), and inner segment-outer segment (ISOS) layer measurements were extracted using a customized high-density grid. Variations with age, sex, ethnicity, and refractive error were assessed with multiple linear regression analyses, with age-related distributions further assessed using hierarchical cluster analysis and regression models. Models were tested on a naïve healthy cohort (n=40) with Mann-Whitney tests to determine generalizability. Quantitative cell density data were calculated from histological data from previous human studies. Eccentricity-dependent variations in OCT retinal thickness closely resemble topographic cell density maps from human histological studies. Age was consistently identified as significantly impacting retinal thickness (p=.0006, .0007, and .003 for GCL, INL and ISOS), with gender affecting ISOS only (p<.0001). Regression models demonstrated that age-related changes in the GCL and INL begin in the 30th decade and were linear for the ISOS. Model testing revealed significant differences in INL and ISOS thickness (p=.0008 and .0001; however, differences fell within the OCT's axial resolution. Qualitative comparisons show close alignment between OCT and histological cell densities when using unique, high-resolution OCT data, and correction for demographics-related variability. Overall, this study describes a process to calculate in vivo cell density from OCT for all neural layers of the human retina, providing a framework for basic science and clinical investigations.

Chronic glaucoma in rats induced by single injection of fibronectin‐loaded PLGA microspheres

AbstractPurpose: To generate a model of chronic glaucoma in rats, by means of a single injection that simulates the pathology that occurs in humans.Methods: A total of 47 Long‐Evans rats of both sexes were used; 30 rats received an intracameral injection of a suspension of fibronectin‐loaded poly‐lactic‐glycolic acid microspheres into the right eye, and the other 17 served as controls. They were followed up for 24 weeks, evaluating intraocular pressure (IOP) with a rebound tonometer, neuro‐retinal structure by optical coherence tomography (OCT) with segmentation protocols for the analysis of the entire retina, the ganglion cell layer (GCL) and the peripapillary retinal nerve fibre layer (pRNFL); as well as retinal functionality by electroretinography (ERG).Results: The IOP of the induced eyes increased progressively and chronically (11.64 ± 1.43 to 21.89 ± 3.94 mmHg) compared to the controls (p = 0.025) and with higher levels than the contralateral eyes (p &lt; 0.05) until week 20, when this trend reversed. The induced eyes showed fluctuations in OCT retinal thickness over time. A trend of less thickness in the retina and GCL was measured in the induced eye and its contralateral eye; but at the end of the study, greater thicknesses were quantified than in the control eyes (p = 0.036). In addition, a lower ERG signal was recorded in the induced eyes. Ganglion cell functionality progressively decreased and was lower than contralateral eyes and control eyes at 12 and 24 weeks (p &lt; 0.05). Males showed higher IOP (p &lt; 0.05), greater thicknesses in the retina and lesser in the GCL and pRNFL (p &lt; 0.05), with decreased functionality at 12 and 24 weeks compared to females.Conclusions: A minimally invasive chronic glaucoma model was obtained using single‐injection by pharmaceutical technology, which produced a progressive increase in intraocular pressure and structural and functional neuro‐retinal damage.

OCT retinal nerve fiber layer thickness differentiates acute optic neuritis from MOG antibody-associated disease and Multiple Sclerosis: RNFL thickening in acute optic neuritis from MOGAD vs MS

BackgroundOptic neuritis (ON) is the most common manifestation of myelin oligodendrocyte glycoprotein antibody associated disorder (MOGAD) and multiple sclerosis (MS). Acute ON in MOGAD is thought to be associated with more severe optic disk edema than in other demyelinating diseases, but this has not been quantitatively confirmed. The goal of this study was to determine whether optical coherence tomography (OCT) can distinguish acute ON in MOGAD from MS, and establish the sensitivity of OCT as a confirmatory biomarker of ON in these entities. MethodsThis was a multicenter cross-sectional study of MOGAD and MS patients with peripapillary retinal nerve fiber layer (pRNFL) thickness measured with OCT within two weeks of acute ON symptom. Cirrus HD-OCT (Carl Zeiss Meditec, Inc. Dublin, CA, USA) was used to measure the pRNFL during acute ON. Eyes with prior ON or disk pallor were excluded. A receiver operating characteristic (ROC) curve analysis was performed to assess the ability of pRNFL thickness to distinguish MOGAD from MS. ResultsSixty-four MOGAD and 50 MS patients met study inclusion criteria. Median age was 46.5 years (interquartile range [IQR]: 34.3–57.0) for the MOGAD group and 30.4 years (IQR: 25.7–38.4) for the MS group (p<0.001). Thirty-nine (61%) of MOGAD patients were female compared to 42 (84%) for MS (p = 0.007). The median pRNFL thickness was 164 µm (IQR: 116–212) in 96 acute MOGAD ON eyes compared to 103 µm (IQR: 93–113) in 51 acute MS ON eyes (p<0.001). The ROC area under the curve for pRNFL thickness was 0.81 (95% confidence interval 0.74–0.88) to discriminate MOGAD from MS. The pRNFL cutoff that maximized Youden's index was 118 µm, which provided a sensitivity of 74% and specificity of 82% for MOGAD. Among 31 MOGAD and 48 MS eyes with an unaffected contralateral eye or a prior baseline, the symptomatic eye had a median estimated pRNFL thickening of 45 µm (IQR: 17–105) and 7.5 µm (IQR: 1–18), respectively (p<0.001). All MOGAD affected eyes had a ≥ 5 µm pRNFL thickening, whereas 26 (54%) MS affected eyes had a ≥ 5 µm thickening. ConclusionOCT-derived pRNFL thickness in acute ON can help differentiate MOGAD from MS. This can aid with early diagnosis and guide disease-specific therapy in the acute setting before antibody testing returns, and help differentiate borderline cases. In addition, pRNFL thickening is a sensitive biomarker for confirming acute ON in MOGAD, which is clinically helpful and could be used for adjudication of attacks in future MOGAD clinical trials.

Effects of Flavonoid Glycoside on Mitochondrial Dysfunction and Inflammatory Oxidative Stress in Macular Degeneration

This study aimed to investigate the effects of flavonoid glycoside on mitochondrial dysfunction and inflammatory oxidative stress in macular degeneration. Sixty specific-pathogen-free male Bagg and Albino mice were randomly divided into control, model and flavonoid glycoside. Human retinal pigment epithelium cells ARPE-19 were cultured and treated with dimethyl sulfoxide, sodium iodate and flavonoid glycoside respectively. Fundus fluorescein angiography was used to detect the number of mouse retinal leakage; optical coherence tomography retinal thickness. A wave and B wave were detected by electroretinogram. Hematoxylin and eosin staining was used to observe the morphology of mouse retina; phalloidin, translocase of the outer mitochondrial membrane complex subunit 20 and cyclooxygenase III staining were performed on mouse retinal pigment epithelium cells by immunofluorescence. Adenosine triphosphate content in retinal pigment epithelium cells of mice in each group was detected. Compared with the control mice, the number of retinal leakage points in the model increased, the retinal thickness, A wave and B wave decreased, and the levels of Fas and FasL protein increased significantly. After treatment with flavonoid glycoside, the number of retinal leakage decreased the retinal thickness, A wave and B wave increased, and the levels of Fas and FasL protein decreased significantly. Flavonoid glycoside can significantly improve the mitochondrial dysfunction and inflammatory oxidative stress of retinal pigment epithelium cells and play a good role in protecting macular degeneration.

Agreement Between Spectral-Domain and Swept-Source Optical Coherence Tomography Retinal Thickness Measurements in Macular and Retinal Disease.

IntroductionTo assess inter-device agreement in optical coherence tomography-derived retinal thickness measurements in patients with known macular conditions between spectral-domain and swept-source optical coherence tomography (OCT). MethodsTwo hundred seventy-two subjects were included in the study. They consisted of 91 male (33.5%) and 181 female (66.5%) subjects, and 132 left (48.5%) and 140 right (51.5%) eyes. Each subject underwent spectral-domain OCT (SD-OCT, Spectralis, Heidelberg Engineering; RTVue XR Avanti XR HD, Optovue) and swept-source OCT (SS-OCT; DRI-OCT-1, Atlantis, Topcon) in a single imaging session performed by the same clinical trial-certified technician. The comparison of retinal thickness reproducibility between devices was performed using Bland–Altman analyses and across the entire data set using the intraclass correlation coefficient (ICC).ResultsThe ICC of the retinal thickness measurements (95% confidence interval) made using all three OCT instruments was 0.81 (0.77–0.84). The mean difference in mean retinal thickness between Spectralis SD-OCT and Topcon SS-OCT was 59.1 μm (95% limit of agreement [LoA] −21.7 to 139.8 μm). The mean difference in mean retinal thickness between Optovue SD-OCT and Topcon SS-OCT was 21.8 μm (95% LoA −34.7 to 78.3 μm).ConclusionsRetinal layer thickness measurements vary between SS-OCT and SD-OCT devices. We describe inter-device agreement in retinal thickness between SS-OCT and SD-OCT in patients with macular conditions. Clinicians should be aware of the differences in retinal thickness values when imaging patients using different OCT devices and should consider using the same OCT device model in order to monitor clinical change.Trial RegistrationClinicalTrials.gov Identifier (NCT02828215).

Neuroretinal Biomarkers for Schizophrenia Spectrum Disorders.

PurposeWe evaluated the patient-control differences and predictive value of the retina as potential biomarkers for schizophrenia.MethodsThe institutional study included both eyes of 58 schizophrenia spectrum disorder (SSD) patients (age 37.2 ± 12.3 years) and 35 controls (age 41.1 ± 15.2 years). Retinal nerve fiber layer (RNFL), ganglion cell–inner plexiform layer, outer retinal photoreceptor complex, and total macula thicknesses were measured by optical coherence tomography (OCT). Anterior segment parameters including central corneal thickness, anterior chamber depth, and axial length were measured to rule out confounds on the retinal measures.ResultsThe peripapillary RNFL was overall significantly thinner in SSD relative to controls (F = 3.97, P = 0.049), most pronounced in the temporal (5.2 µm difference, F = 6.95, P = 0.010) and inferior quadrants (12.1 µm difference, F = 7.32, P = 0.009). There were no significant group differences in thickness for the macular RNFL, ganglion, or photoreceptor cell related measures (P > 0.05). Peripapillary RNFL, central macula, and outer photoreceptor complex thicknesses were together able to classify SSD patients with 80% sensitivity and 71% specificity; area under the curve = 0.82 (95% confidence interval, 0.75–0.88).ConclusionsSSD patients exhibited significant RNFL thinning relative to controls. Notably, retinal thickness measures including both peripapillary and macular data exhibited improved diagnostic accuracy for SSD as compared to these regions alone.Translational RelevanceThis is the first study to evaluate the predictive value of both the inner and outer retina in SSD. OCT retinal thickness measures including peripapillary data in conjunction with macular data may provide an informative, noninvasive in vivo ocular biomarker for schizophrenia.

Diagnosis and Grading Of Papilledema Using Optical Coherence Tomography Compared To Clinical Staging By Frise´n Scale.

Background:Papilledema, or optic disc swelling due to raised intracranial pressure, has been graded using the Frise´ n Scale. Objectives: In this study we aim to compare and contrast 2 methods of quantitating papilledema, namely, Optical coherence tomography (OCT) and Modified Frise´n Scale (MFS). Materials and method:This study was performed at ophthalmology department, Qena Faculty of Medicine, South Valley University from June 2019 to January 2020, thirty patients with papilledema were enrolled, assessment of OCT retinal nerve fiber layer thickness, OCT total retinal thickness, then compared by modified Frise´n scale from photographs. Results:Our study included 30 patients, 26 females with mean age 28.2±6.7 and 4 males with mean age 32±2, Among 30 patients with papilledema: 7(21) % had grade 1, 10(30) % had grade 2, 4(12) % had grade 3, 9(27) % had grade 4. When OCT RNFL thickness was compared with MFS grade from photographs (using majority rule), Spearman rank correlation was 0.727 (P<0.0005). When OCT total retinal thickness was compared with MFS grade from photographs, Spearman rank correlation was 0.789(P<0.0005). Conclusions: In grading papilledema, we found strong correlation between the modified Frise´n scale and OCT findings. For lower-grade optic disc edema, OCT compares better with clinical staging of optic nerve head photographs. With higher grades of edema, OCT RNFL thickness processing algorithms often fail or lack sensitivity, while OCT total retinal thickness performing more favorably

Spatial Linear Mixed Effects Modelling for OCT Images: SLME Model.

Much recent research focuses on how to make disease detection more accurate as well as “slimmer”, i.e., allowing analysis with smaller datasets. Explanatory models are a hot research topic because they explain how the data are generated. We propose a spatial explanatory modelling approach that combines Optical Coherence Tomography (OCT) retinal imaging data with clinical information. Our model consists of a spatial linear mixed effects inference framework, which innovatively models the spatial topography of key information via mixed effects and spatial error structures, thus effectively modelling the shape of the thickness map. We show that our spatial linear mixed effects (SLME) model outperforms traditional analysis-of-variance approaches in the analysis of Heidelberg OCT retinal thickness data from a prospective observational study, involving 300 participants with diabetes and 50 age-matched controls. Our SLME model has a higher power for detecting the difference between disease groups, and it shows where the shape of retinal thickness profiles differs between the eyes of participants with diabetes and the eyes of healthy controls. In simulated data, the SLME model demonstrates how incorporating spatial correlations can increase the accuracy of the statistical inferences. This model is crucial in the understanding of the progression of retinal thickness changes in diabetic maculopathy to aid clinicians for early planning of effective treatment. It can be extended to disease monitoring and prognosis in other diseases and with other imaging technologies.

Correlation of Optical Coherence Tomography and Retinal Histology in Normal and Pro23His Retinal Degeneration Pig.

PurposeWe correlate optical coherence tomography (OCT) retinal layer thickness measurements with histology in wild-type and retinal degenerative pigs.MethodsOCT scans were obtained using the Bioptigen Envisu R2200. In normal pigs, three eyes were imaged in vivo, and three eyes were imaged after enucleation. In the Pro23His retinal degeneration pigs (P23H), one eye was imaged in vivo and four eyes were imaged after enucleation. All eyes were fixed in 4% paraformaldehyde and processed for histology. Corresponding retinal locations on OCT and histology were identified using anatomic landmarks (optic nerve, retinal vessels, visual streak). Individual retinal layer thicknesses were measured by two independent, masked graders, and intraclass correlation coefficients were used to determine agreement. OCT and histologic retinal thickness measurements were averaged and compared.ResultsOCT and histologic measurements correlated highly in normal and diseased eyes (R2 = 0.91 and 0.92, respectively), and scans performed in vivo and ex vivo did not differ significantly. Despite good overall correlation, certain individual retinal layers (e.g., retinal nerve fiber layer [NFL], inner [INL] and outer [ONL] nuclear layers) appeared thicker on OCT compared to histology, while other layers (e.g., retinal pigment epithelium) appeared thinner. No statistically significant difference was found between OCT and histology for any retinal layer thickness measurement.ConclusionsRetinal layer thickness measurements correlate well with histology in pig eyes, but differences in individual retinal layers may be seen.Translational RelevanceOCT may be used in pigs to measure retinal thicknesses with good overall correlation to histologic measurements.

Analysis of changes in individual retinal layer thickness after cataract surgery using spectral‐domain optical coherence tomography

PurposeTo evaluate whether there were significant changes in macular thickness and each retinal layer thickness after cataract surgery using spectral‐domain optical coherence tomography (OCT)MethodsFrom February to August 2015, a prospective study of 24 eyes of 14 patients, who underwent cataract surgery was conducted. The thickness of each retinal layer was measured with OCT before and one month after surgery. The changes in OCT signal strength and retinal thickness before and after surgery were compared, and the layers more affected were confirmed. Also, correlation analysis was performed to determine the relationship between changes in signal strength, severity of cataract, and changes in refractive index and retinal thickness.ResultsThe mean macular thickness was significantly increased from 263.33 μm to 269.75 μm (p = 0.019). When examining the changes in each retinal layer thickness, there was a significant increase in the thickness of the inner plexiform layer (p = 0.034), outer nuclear layer (p = 0.015) and retinal pigment epithelium (RPE) (p = 0.012). The signal strength of OCT was significantly increased from 28.79 dB to 31.67 dB (p = 0.005), which was significantly correlated with postoperative macular thickness changes (p = 0.046). However, the severity of cataract (p = 0.219) or the change of refractive index (p = 0.098) was not significantly correlated with macular thickness changes.ConclusionsAfter cataract surgery, both improvement of signal strength and structural changes of the retina may increase macular thickness. In particular, the thickness of the inner plexiform layer, outer nuclear layer, and retinal pigment epithelial layer increased. Therefore, the thickness of ganglion cell‐inner plexiform layer after cataract surgery may increase, so it should be carefully considered in the assessment of glaucoma progression.

Preserved functional and structural integrity of the papillomacular area correlates with better visual acuity in retinitis pigmentosa.

PurposeLinking multifocal electroretinography (mfERG) and optical coherence tomography (OCT) findings with visual acuity in retinitis pigmentosa (RP) patients.DesignProspective, cross-sectional, nonintervention study.SubjectsPatients with typical RP and age-matched controls, who underwent SD-OCT (spectral domain OCT) and mfERG, were included.MethodsMfERG responses were averaged in three zones (zone 1 (0°-3°), zone 2 (3°-8°), and zone 3 (8°-15°)). Baseline-to-trough- (N1) and trough-to-peak amplitudes (N1P1) of the mfERG were compared with corresponding areas of the OCT. The papillomacular area (PMA) was analyzed separately. Correlations between best-corrected visual acuity (BCVA, logMAR) and each parameter were determined.Main outcome measuresComparing structural (OCT) and functional (mfERG) measures with the BCVA.ResultsIn RP patients, the N1 and N1P1 responses showed positive association with the central retinal thickness outside zone 1 (P≤0.002), while the central N1 and the N1P1 responses in zones 1, 2, and 3-with the BCVA (P≤0.007). The integrity of the IS/OS line on OCT showed also a positive association with the BCVA (P<0.001). Isolated analysis of the PMA strengthened further the structure-function association with the BCVA (P≤0.037). Interactions between the BCVA and the OCT, respectively, the mfERG parameters were more pronounced in the RP subgroup without macular edema (P≤0.020).ConclusionIn RP patients, preserved structure-function of PMA, measured by mfERG amplitude and OCT retinal thickness, correlated well with the remaining BCVA. The subgroup analyses revealed stronger links between the examined parameters, in the RP subgroup without appearance of macular edema.

Glaucoma diagnostic capacity of optic nerve head haemoglobin measures compared with spectral domain OCT and HRT III confocal tomography.

The computer program laguna onhe determines optic nerve head haemoglobin (ONH Hb) on retinal photographs based on detecting colour differences. This study compares the diagnostic capacity of Laguna ONhE with that of spectral domain optical coherence tomography (OCT) and confocal tomography (HRT III). In a prospective, observational, cross-sectional study, glaucomatous (n=66) and healthy (n=52) eyes were examined by Spectralis OCT, HRT III and Laguna ONhE. The following Laguna ONhE variables were determined: ONH Hb across the vertical disc diameter (8&20Hb), estimated cup-disc ratio (C/D) and the glaucoma discriminant function (GDF), which combines the slope of Hb amount with the mean in 8&20Hb. The three diagnostic methods were compared by calculating areas under ROC curves (AUCs). Correlations between variables were assessed through Spearman's rho coefficient. Areas under ROC curves (AUCs) were 0.785 (95% CI: 0.700-0.863) for GDF, 0.807 (95% CI: 0.730-0.883) for OCT retinal nerve fibre layer thickness (OCT-RNFL) and 0.714 (95% CI: 0.618-0.810) and 0.721 (95% CI: 0.628-0.815) for the HRT III variable GPS (glaucoma probability score) and vertical C/D ratio, respectively. Glaucoma discriminant function (GDF) was correlated with OCT-RNFL (0.587, p 0.001; 0.507, p 0.045; and -0.119, p 0.713 for mild, moderate and advanced glaucoma, respectively), mostly so with inferior OCT-RNFL (0.622; p<0.001). Glaucoma discriminant function (GDF)-HRT III correlations were lower (rim area 0.471, p<0.0001; rim/disc area 0.426, p<0.0001; vertical C/D -0.413, p<0.0001; GPS -0.408, p<0.0001; rim volume 0.341, p<0.0001). Similar diagnostic power was observed for Laguna ONhE, Spectralis OCT and HRT III.

Assessment of hydroxychloroquine maculopathy after cessation of treatment: an optical coherence tomography and multifocal electroretinography study.

ObjectiveThis study was conducted to evaluate the macular status of patients treated with hydroxychloroquine before and after cessation of treatment.MethodsForty-two patients with systemic lupus erythematosus underwent ocular examination based on visual acuity evaluation, optical coherence tomography retinal thickness measurements, and multifocal electroretinography (mfERG) records at first visit. The tests were repeated 6 months after treatment withdrawal and compared to the findings at their first visit.ResultsMean visual acuity (measured in log minimum angle of resolution) of both eyes was statistically increased after hydroxychloroquine discontinuation (difference in means: 0.06 [P<0.0001] and 0.01 [P=0.003] for the right and left eyes, respectively). Retinal response amplitudes of central and peripheral areas were significantly improved for both eyes. The following values were observed for central responses: the difference in means was −19.9 (P<0.0001) and −13.6 (P<0.0001) for the right eye and the left eye, respectively; for peripheral responses, difference in means was −10.3 (P<0.0001) and −9.5 (P<0.0001) for right eye and left eye, respectively, after the 6-month examination. There were no statistically significant differences in the retinal thickness of patients after cessation of treatment. The visual acuity of the patients was correlated to central and peripheral mfERG responses (r=−0.53 [P<0.0001] and r=−0.53 [P<0.0001], for the right eye and the left eye, respectively).ConclusionThe visual acuity of patients receiving hydroxychloroquine improves along with the amplitudes of the mfERG responses 6 months after discontinuation of the drug, but no difference in retinal thickness is identified.

Improved repeatability of retinal thickness measurements using line-scan ophthalmoscope image-based retinal tracking.

To assess repeatability and speed of a line-scan ophthalmoscope (LSO) image-based tracking system and compare to the point-scanning approach. Thirty-five eyes with retinal diseases underwent volume scans using two spectral-domain optical coherence tomography (OCT) devices: a line-scan tracking Cirrus HD-OCT (Carl Zeiss Meditec; Dublin, CA) and point-scan tracking Spectralis HRA+OCT (Heidelberg Engineering, Heidelberg, Germany). Eyes were also imaged on the Cirrus HD-OCT with tracking disabled. Mean difference in central subfield thickness (CST) between consecutive scans was 2.6 µm for the Cirrus without tracking, 1.7 µm with tracking, and 3.6 µm for the Spectralis. The repeatability standard deviation was 3.0 µm for the Cirrus without tracking, 1.5 µm with tracking, and 4.0 µm for the Spectralis. Coefficient of variation for the CST was 1.1% for the Cirrus without tracking, 0.5% with tracking, and 1.4% for the Spectralis. Mean scan acquisition time was 12.3 ± 6.2 seconds for the Spectralis, 7.8 ± 6.7 for the Cirrus with tracking, and 4.3 ± 0.6 for the Cirrus without tracking. Real-time LSO image-based retinal tracking appears to improve repeatability of OCT retinal thickness measurements.

Reproducibility of Optovue RTVue Optical Coherence Tomography Retinal Thickness Measurements and Conversion to Equivalent Zeiss Stratus Metrics in Diabetic Macular Edema.

To evaluate the reproducibility of central subfield thickness (CST) and volume measurements from optical coherence tomography (OCT) images obtained with Zeiss Stratus and Optovue RTVue, and formulate equations to convert these measurements from RTVue to 'equivalent' Stratus values. Cross-sectional observational study from 309 eyes of 167 participants with diabetes and at least one eye with central-involved diabetic macular edema (DME; Stratus CST ≥ 250 μm) that underwent two replicate Stratus scans followed by two replicate RTVue scans centered on the fovea. The Bland-Altman coefficient of repeatability for relative change in CST (the degree of change that could be expected from measurement variability) was not significantly different on Stratus and RTVue scans (10% and 16%, respectively). The replicate Stratus CST was within 10% of the initial Stratus measurement 93% of the time; the CST conversion equation predicted a Stratus value calculated from the observed RTVue value within 10% of the observed Stratus thickness 91% of the time. Bland-Altman limit of agreement for relative change in CST between measurements observed on different machines was 23%, comparing predicted versus actual Stratus measurement. RTVue thickness reproducibility appears similar to Stratus. Conversion equations to transform RTVue measurements to Stratus-equivalent values within 10% of the observed Stratus RT are feasible. CST changes greater than 10% when using the same machine or 20% when switching from Stratus to RTVue, after conversion to Stratus equivalents, are likely due to a true change beyond measurement error. Conversion equations to translate central retinal thickness measurements between OCT instruments is critical to clinical trials.

Subjective and Objective Screening Tests for Hydroxychloroquine Toxicity

To compare subjective and objective clinical tests used in the screening for hydroxychloroquine retinal toxicity to multifocal electroretinography (mfERG) reference testing. Prospective, single-center, case control study. Fifty-seven patients with a previous or current history of hydroxychloroquine treatment of more than 5 years' duration. Participants were evaluated with a detailed medical history, dilated ophthalmologic examination, color fundus photography, fundus autofluorescence (FAF) imaging, spectral-domain (SD) optical coherence tomography (OCT), automated visual field testing (10-2 visual field mean deviation [VFMD]), and mfERG testing. We used mfERG test parameters as a gold standard to divide participants into 2 groups: those affected by hydroxychloroquine-induced retinal toxicity and those unaffected. We assessed the association of various imaging and psychophysical variables in the affected versus the unaffected group. Fifty-seven study participants (91.2% female; mean age, 55.7±10.4 years; mean duration of hydroxychloroquine treatment, 15.0±7.5 years) were divided into affected (n= 19) and unaffected (n= 38) groups based on mfERG criteria. Mean age and duration of hydroxychloroquine treatment did not differ statistically between groups. Mean OCT retinal thickness measurements in all 9 macular subfields were significantly lower (<40 μm) in the affected group (P < 0.01 for all comparisons) compared with those in the unaffected group. Mean VFMD was 11 dB lower in the affected group (P < 0.0001). Clinical features indicative of retinal toxicity were scored for the 2 groups and were detected in 68.4% versus 0.0% using color fundus photographs, 73.3% versus 9.1% using FAF images, and 84.2% versus 0.0% on the scoring for the perifoveal loss of the photoreceptor ellipsoid zone on SD-OCT for affected and unaffected participants, respectively. Using a polynomial modeling approach, OCT inner ring retinal thickness measurements and Humphrey 10-2 VFMD were identified as the variables associated most strongly with the presence of hydroxychloroquine as defined by mfERG testing. Optical coherence tomography retinal thickness and 10-2 VFMD are objective measures demonstrating clinically useful sensitivity and specificity for the detection of hydroxychloroquine toxicity as identified by mfERG, and thus may be suitable surrogate tests.

Optical Coherence Tomography Retinal Thickness and Volume Measurements in X-Linked Retinoschisis

To analyze retinal thickness and volume measurements of X-linked retinoschisis patients by spectral-domain optical coherence tomography (SD OCT) and correlate these findings with visual acuity and patient age. Retrospective comparative case series. Sixty-three eyes of 33 male patients with X-linked retinoschisis were gleaned from a SD OCT database at the University of Illinois at Chicago. Forty-one eyes of 21 patients with low refractive error, no visualimpairment, and no known retinal disease served as age-similar controls. The mean age of the retinoschisis patients was 26.4 years. The mean age of patient controls was 30.0 years. Full-thickness, inner and outer retina thickness, and volume measurements were determined by SD OCT. Foveal schisis was observed in 81% of retinoschisis patients. Patients with foveal schisis tended to be younger than patients lacking foveal schisis. Inner and outer foveal thickness and volume measurements were increased in retinoschisis patients compared to controls. Outer retinal perifoveal and parafoveal thicknesses and volumes were consistently increased in retinoschisis patients relative to controls. In contrast, inner retinal perifoveal and parafoveal thickness and volume measurements were decreased in retinoschisis patients compared to controls. Worse visual acuity correlated with thinning of the temporal perifoveal inner retina and thickening of the inner fovea. Full-thickness measurements and inner retina and outer retina thickness and volume measurements tended to decrease with patient age. Increased inner retinal foveal thickness and decreased perifoveal inner retinal thickness correlates with worse visual acuity and overall retinal thickness decreases with age in X-linked retinoschisis.

Functional and morphological changes in diabetic macular edema over the course of anti-vascular endothelial growth factor treatment

To evaluate macular morphology and function in diabetic macular edema (DME) over the course of intravitreal anti-vascular endothelial growth factor (VEGF) treatment with Ranibizumab. A consecutive series of 39 study eyes with centre-involving DME were included in this study. In all subjects, best-corrected visual acuity (BCVA) according ETDRS protocol, fluorescein angiography (FA), microperimetric macular sensitivity (MP) and Spectral Domain optical coherence tomography (SD-OCT) cross-sectional scans were obtained before treatment and after 3 monthly applied intravitreal Ranibizumab injections. Six different morphological qualities [IS/OS layer integrity, outer nuclear layer (ONL) cysts, ONL cyst size, inner nuclear layer (INL) cysts, blocking phenomenon and subretinal fluid] were graded of each cross-sectional OCT scan before and over the course of treatment by two experienced graders. Correlation analyses between functional and morphological parameters were obtained. Mean BCVA increased from 26 ± 14 to 33 ± 13 letters after 3 consecutive monthly applied Ranibizumab injections (p < 0.001). Central retinal thickness (CRT) decreased from 504 ± 144 to 387 ± 122 μm (p < 0.001). Over the course of treatment, IS/OS continuity improved (index: 0.56 ± 0.52 to 0.43 ± 0.49, Z = -1.415, p = 0.157), ONL cyst prevalence and size decreased significantly (index: 0.61 ± 0.44 to 0.56 ± 0.35, Z = -3.41, p = 0.001 and 1.75 ± 0.88 to 1.17 ± 1.05, Z = -4.02, p < 0.001), INL cyst prevalence decreased (index: 0.35 ± 0.52 to 0.28 ± 0.52, Z = -1.60, p = 0.109), blocking phenomenon did not change significantly (index: 00.12 ± 0.16 to 0.13 ± 0.15, Z = -0.45, p = 0.656) and subretinal fluid almost disappeared (index: 0.10 ± 0.24 vs. 0.00 ± 0.01, Z = -2.56, p = 0.011). Correlation analyses revealed highest significant correlations between ONL cyst prevalence and their size and CRT as well as BCVA and MP before treatment and over the course of treatment. ONL cysts and their size as morphological parameters correlate with retinal function measured with BCVA and microperimetry before and over the course of anti-VEGF therapy with Ranibizumab in patients with DME.

Repeatability of retinal thickness and volume metrics in neovascular age‐related macular degeneration using the Heidelberg spectralis optical coherence tomography

AbstractPurpose To estimate the intra‐session repeatability of retinal thickness and volume measurements from consecutive raster Heidelberg Spectralis spectral‐domain optical coherence tomography (OCT) scans in patients with neovascular age‐related macular degeneration (nAMD).Methods Retrospective analysis of Spectralis OCT scans taken from 27 patients with a diagnosis of nAMD. Three OCT raster scans were performed by the same observer in the same sitting in consecutive patients attending for nAMD treatment, one of which being taken as a follow‐up after setting a reference point on the baseline scan and one being taken as an independent scan from the baseline one. Retinal thickness and volume measurements were automatically calculated by the onboard software. Bland‐Altman methods of analysis were used to assess repeatability.Results Data from the 27 patients were analyzed with a mean (SD) age of 78 years (7). Mean visual acuity was 20/63 (range 20/200‐20/32) The 95% coefficient of repeatability (CR) was 44 µm and 0.038 mm3 for retinal thickness and volume respectively in the central 1 mm macular subfield for the two independent scans, and it was 32 µm and 0.027 mm3 for the two scans taken with the follow‐up reference.Conclusion We report estimates of the intra‐session repeatability of Spectralis OCT retinal thickness and volume metrics in patients with nAMD. There were comparable repeatability estimates for scans taken with or without setting a reference scan with the onboard software. The results are helpful in distinguishing clinical change from measurement variability in clinical practice.