1. Articles from brad fortune

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    1. A high-accuracy and high-efficiency digital volume correlation method to characterize in-vivo optic nerve head biomechanics from optical coherence tomography

      A high-accuracy and high-efficiency digital volume correlation method to characterize in-vivo optic nerve head biomechanics from optical coherence tomography

      In-vivo optic nerve head (ONH) biomechanics characterization is emerging as a promising way to study eye physiology and pathology. We propose a high-accuracy and high-efficiency digital volume correlation (DVC) method for the purpose of characterizing the in-vivo ONH deformation from volumes acquired by optical coherence tomography (OCT). Using a combination of synthetic tests and analysis of OCTs from monkey ONHs subjected to acute and chronically elevated intraocular pressure, we demonstrate that our proposed methodology overcomes several challenges for conventional DVC methods. First, it accounts for large ONH rigid body motion in the OCT volumes which could otherwise lead to analysis ...

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    2. OCT Optic Nerve Head Morphology in Myopia I: Implications of Anterior Scleral Canal Opening versus Bruch’s Membrane Opening Offset

      OCT Optic Nerve Head Morphology in Myopia I: Implications of Anterior Scleral Canal Opening versus Bruch’s Membrane Opening Offset

      Purpose To measure the magnitude and direction of anterior scleral canal opening (ASCO) offset relative to Bruch’s membrane opening (BMO) (ASCO/BMO offset) in order to characterize neural canal obliqueness and minimum cross-sectional area (NCMCA) in 69 highly myopic and 138 healthy, age-matched, control eyes. Design: Cross-sectional study. Methods Using Optic Coherence Tomography (OCT) scans of the optic nerve head (ONH), BMO and ASCO were manually segmented and their centroids, size and shape were calculated. ASCO/BMO offset magnitude and direction were measured after projecting the ASCO/BMO centroid vector onto the BMO plane. Neural canal axis obliqueness was ...

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    3. OCT Structural Abnormality Detection in Glaucoma using Topographically Correspondent Rim and Retinal Nerve Fiber Layer Criteria

      OCT Structural Abnormality Detection in Glaucoma using Topographically Correspondent Rim and Retinal Nerve Fiber Layer Criteria

      Purpose To evaluate the ability of topographically correspondent (TC) minimum rim width (MRW) and peripapillary retinal nerve fiber layer thickness (pRNFLT) criteria to detect optical coherence tomography (OCT) structural abnormality in glaucoma (GL) and glaucoma suspect (GLS) eyes. Design Retrospective cross-sectional study. Methods 196 GL, 150 GLS eyes and 303 Heathy eyes underwent PRNFL and 24 radial optic nerve head OCT imaging and manual correction of the internal limiting membrane, Bruch’s membrane opening (BMO) and outer pRNFL segmentations. MRW and pRNFLT were quantified in six Garway-Heath (GH) or twelve 30° (clock-hour) sectors. OCT abnormality for each parameter was defined ...

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    4. Effect of Trabeculectomy on Optical Coherence Tomography (OCT) Measurements of the Optic Nerve Head Neuroretinal Rim Tissue

      Effect of Trabeculectomy on Optical Coherence Tomography (OCT) Measurements of the Optic Nerve Head Neuroretinal Rim Tissue

      Purpose Ophthalmologists commonly perform glaucoma surgery to treat progressive glaucoma. Few studies have examined the stability of OCT neuroretinal rim parameters after glaucoma surgery for ongoing detection of glaucoma progression. Design Longitudinal cohort study. Participants 20 eyes (16 subjects) with primary open angle glaucoma who had undergone a trabeculectomy. Methods We calculated the change in OCT parameters (minimum rim area (MRA), minimum rim width (MRW), Bruch’s membrane opening (BMO) area, mean cup depth (MCD), anterior lamina cribrosa surface depth (ALCSD), prelaminar tissue thickness (PLTT), retinal nerve fiber layer thickness (RFNLT) during an interval from the visit before the surgery ...

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    5. OCT-Detected Optic Nerve Head Neural Canal Direction, Obliqueness and Minimum Cross-Sectional Area in Healthy Eyes

      OCT-Detected Optic Nerve Head Neural Canal Direction, Obliqueness and Minimum Cross-Sectional Area in Healthy Eyes

      Purpose To assess anterior scleral canal opening (ASCO) offset relative to Bruch’s membrane opening (BMO) (ASCO/BMO offset) so as to determine neural canal direction, obliqueness, and minimum cross-sectional area (NCMCA) in 362 healthy eyes. Design Cross-sectional study Methods After OCT optic nerve head (ONH) and retinal nerve fiber layer thickness (RNFLT) imaging, BMO and ASCO were manually segmented and planes, centroids, size and shape were calculated. Neural canal direction was defined by projecting the neural canal axis vector (connecting BMO and ASCO centroids) onto the BMO plane. Neural canal obliqueness was defined by the angle between the neural ...

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    6. Optical Coherence Tomography Segmentation Errors of the Retinal Nerve Fiber Layer Persist Over Time

      Optical Coherence Tomography Segmentation Errors of the Retinal Nerve Fiber Layer Persist Over Time

      Précis: There are errors in automated segmentation of the retinal nerve fiber layer in glaucoma suspects or patients with mild glaucoma that appear to persist over time; however, automated segmentation has greater repeatability than manual segmentation. Purpose: To identify whether optical coherence tomography (OCT) segmentation errors in retinal nerve fiber layer (RNFL) thickness measurements persist longitudinally. Methods: This was a cohort study. We used spectral domain OCT (Spectralis, Heidelberg Engineering, Heidelberg, Germany) to measure RNFL thickness in a 6-degree peripapillary circle, and exported the native “automated segmentation only” results. In addition, we exported RNFL thickness results after “manual refinement ...

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    7. Factors Influencing Optical Coherence Tomography Peripapillary Choroidal Thickness: A Multicenter Study

      Factors Influencing Optical Coherence Tomography Peripapillary Choroidal Thickness: A Multicenter Study

      Purpose : To quantify peripapillary choroidal thickness (PCT) and the factors that influence it in healthy participants who represent the racial and ethnic composition of the U.S. population. Methods : A total of 362 healthy participants underwent optical coherence tomography (OCT) enhanced depth imaging of the optic nerve head with a 24 radial B-scan pattern aligned to the fovea to Bruch's membrane opening axis. Bruch's membrane, anterior scleral canal opening (ASCO), and the anterior scleral surface were manually segmented. PCT was measured at 100, 300, 500, 700, 900, and 1100 μm from the ASCO globally and within 12 clock-hour ...

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    8. An Examination of the Frequency of Paravascular Defects and Epiretinal Membranes in Eyes With Early Glaucoma Using En-face Slab OCT Images

      An Examination of the Frequency of Paravascular Defects and Epiretinal Membranes in Eyes With Early Glaucoma Using En-face Slab OCT Images

      Purpose: To examine the frequency of paravascular defects (PDs) and macular epiretinal membranes (ERMs) in eyes categorized as having mild glaucoma or glaucoma suspect using en-face slab analysis of optical coherence tomography (OCT) scans. Materials and Methods: Fifty-seven glaucomatous eyes, 44 low-risk suspect eyes, and 101 healthy control eyes were included in the study. The 101 glaucomatous and suspect eyes had a mean deviation better than −6 dB on the 24-2 visual field, and a spherical refractive error between±6 D or axial length <26.5 mm. Two OCT-graders masked to eye classification identified ERMs and PDs on en-face slab ...

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    9. Glaucoma Specialist Detection of Optical Coherence Tomography Suspicious Rim Tissue in Glaucoma and Glaucoma Suspect Eyes.

      Glaucoma Specialist Detection of Optical Coherence Tomography Suspicious Rim Tissue in Glaucoma and Glaucoma Suspect Eyes.

      Purpose To assess glaucoma specialists’ detection of optic nerve head (ONH) rim tissue that is thin by optical coherence tomography (OCT) criteria. Design Reliability analysis Methods 5 clinicians marked the disc margin (DM) and rim margin (RM) on stereo-photos of 151 glaucoma or glaucoma suspect eyes obtained within 3 months of OCT imaging. The photo and OCT infrared image for each eye were colocalized and regionalized into twelve sectors relative to the axis between Bruch’s membrane opening (BMO) centroid and the fovea. For each clinician, the distance from BMO centroid to their DM (DM radius) and RM (RM radius ...

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    10. Optical coherence tomography evaluation of the optic nerve head neuro‐retinal rim in glaucoma

      Optical coherence tomography evaluation of the optic nerve head neuro‐retinal rim in glaucoma

      Clinical examination of the optic disc is a fundamental component of any ophthalmic evaluation, but it is especially important for diagnosis and management of glaucoma. The purpose of this article is to: (1) review the limitations inherent to clinical examination; (2) outline the rationale for adopting into clinical practice quantitative measures of the optic nerve head neuro‐retinal rim tissue integrity derived from current optical coherence tomography imaging approaches; (3) describe recent developments in this area; and (4) highlight a few avenues of active research that hold promise for future translation to clinical practice.

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    11. A Comparison of En Face Optical Coherence Tomography and Fundus Autofluorescence in Stargardt Disease

      A Comparison of En Face Optical Coherence Tomography and Fundus Autofluorescence in Stargardt Disease

      Purpose : To compare morphologic changes on en face images derived from wide-field swept-source optical coherence tomography (ssOCT) to hypo- and hyperautofluorescent (hypoAF, hyperAF) areas on short-wavelength autofluorescence (SW-AF), and near-infrared (NIR)-AF in recessive Stargardt disease (STGD1). Methods : Wide-field ssOCT cube scans were obtained from 16 patients (16 eyes). Averaged B-scans and SW-AF images were obtained using Spectralis HRA+OCT. NIR-AF images were obtained from 6 eyes. The inner/outer segment (IS/OS), OS/RPE, and RPE/Bruch's membrane boundaries were segmented, and en face slab images generated. A subRPE slab image was used to measure the abnormal RPE ...

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    12. Automated segmentation errors when using optical coherence tomography to measure retinal nerve fiber layer thickness in glaucoma

      Automated segmentation errors when using optical coherence tomography to measure retinal nerve fiber layer thickness in glaucoma

      Purpose To characterize the error of optical coherence tomography (OCT) measurements of retinal nerve fiber layer (RNFL) thickness when using automated retinal layer segmentation algorithms without manual refinement. Design: cross-sectional study Methods Setting: glaucoma clinical practice. Study Population: 3490 scans from 412 eyes of 213 individuals with a diagnosis of glaucoma or glaucoma suspect. Observational Procedures: We used spectral domain OCT (Spectralis, Heidelberg Engineering, Heidelberg, Germany) to measure RNFL thickness in a 6-degree peripapillary circle, and exported the native 'automated segmentation only' results. In addition, we exported the results after 'manual refinement' to correct errors in the automated segmentation of ...

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    13. In Vivo Detection of Laminar and Peripapillary Scleral Hypercompliance in Early Monkey Experimental Glaucoma

      In Vivo Detection of Laminar and Peripapillary Scleral Hypercompliance in Early Monkey Experimental Glaucoma

      Purpose : To compare optical coherence tomography (OCT) detected, optic nerve head (ONH) compliance within control and experimental glaucoma (EG) eyes of 15 monkeys at EG onset. Methods : Intraocular pressure (IOP) was chronically elevated in one eye of each animal using a laser. Experimental glaucoma onset was identified using confocal scanning laser tomography (CSLT). Optical coherence tomography ONH imaging (40 radial B-scans) was performed at 10 mm Hg before and after laser. At EG onset, OCT scans were obtained at IOP 10 and 30 mm Hg. Optical coherence tomography landmarks within the IOP 10/30 images were delineated to quantify IOP ...

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    14. Comparing Optic Nerve Head Rim Width, Rim Area, and Peripapillary Retinal Nerve Fiber Layer Thickness to Axon Count in Experimental Glaucoma

      Comparing Optic Nerve Head Rim Width, Rim Area, and Peripapillary Retinal Nerve Fiber Layer Thickness to Axon Count in Experimental Glaucoma

      Purpose : We compare spectral-domain optical coherence tomography (SDOCT) measurements of minimum rim width (MRW), minimum rim area (MRA), and peripapillary retinal nerve fiber layer thickness (RNFLT) to complete orbital optic nerve axon counts in nonhuman primates (NHP) with unilateral experimental glaucoma (EG). Methods : Biweekly SDOCT measurements of MRW, MRA, and RNFLT were acquired under manometric IOP control (10 mm Hg) in 51 NHP during baseline (mean ± SD, 5.0 ± 1.6 sessions) and after laser photocoagulation was applied to the trabecular meshwork of one eye to induce chronic IOP elevation. At the study endpoint (predefined for each NHP), 100% axon ...

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    15. Changes in Retinal Nerve Fiber Layer Reflectance Intensity as a Predictor of Functional Progression in Glaucoma

      Changes in Retinal Nerve Fiber Layer Reflectance Intensity as a Predictor of Functional Progression in Glaucoma

      Purpose : We determined whether longitudinal changes in retinal nerve fiber layer (RNFL) reflectance provide useful prognostic information about longitudinal changes in function in glaucoma. Methods : The reflectance intensity of each pixel within spectral-domain optical coherence tomography (SD-OCT) circle scans was extracted by custom software. A repeatability cohort comprising 53 eyes of 27 participants (average visual field mean deviation [MD] −1.65 dB) was tested five times within a few weeks. To minimize test–retest variability in their data, a reflectance intensity ratio was defined as the mean reflectance intensity of pixels within the RNFL divided by the mean between the ...

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    16. Details of Glaucomatous Damage Are Better Seen on OCT En Face Images Than on OCT Retinal Nerve Fiber Layer Thickness Maps

      Details of Glaucomatous Damage Are Better Seen on OCT En Face Images Than on OCT Retinal Nerve Fiber Layer Thickness Maps

      Purpose : High-resolution images of glaucomatous damage to the retinal nerve fiber layer (RNFL) were obtained with an adaptive optics-scanning light ophthalmoscope (AO-SLO) and used as a basis for comparisons between en face slab images and thickness maps derived from optical coherence tomography (OCT) scans. Methods : Wide-field (9 × 12 mm) cube scans were obtained with swept-source OCT (DRI-OCT) from six eyes of six patients. All eyes had a deep defect near fixation as seen on a 10-2 visual field test. Optical coherence tomography en face images, based on the average reflectance intensity, were generated (ATL 3D-Suite) from 52-μm slabs just ...

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    17. Age-related Differences in Longitudinal Structural Change by Spectral Domain Optical Coherence Tomography in Early Experimental Glaucoma

      Age-related Differences in Longitudinal Structural Change by Spectral Domain Optical Coherence Tomography in Early Experimental Glaucoma

      Purpose. To characterize age-related differences in the magnitude of Spectral Domain Optical Coherence Tomography (SDOCT) structural change in early experimental glaucoma (EG). Methods. Both eyes from 4 young (1.4 - 2.6 yrs) and 4 old (18.6 - 21.9 yrs) rhesus monkeys were imaged at least 3 times at baseline, and then every 2 weeks following laser-induced, chronic, unilateral IOP elevation until the onset of EG (Confocal Scanning Laser Tomographic surface change confirmed twice). Two to 20 weeks after EG onset, animals were sacrificed and optic nerve axon counts for all eyes were performed. Masked operators delineated retinal and ...

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    18. The Effect of Age on Optic Nerve Axon Counts, SDOCT Scan Quality, and Peripapillary Retinal Nerve Fiber Layer Thickness Measurements in Rhesus Monkeys

      The Effect of Age on Optic Nerve Axon Counts, SDOCT Scan Quality, and Peripapillary Retinal Nerve Fiber Layer Thickness Measurements in Rhesus Monkeys

      Purpose: To evaluate the effect of age on optic nerve axon counts, spectral-domain optical coherence tomography (SDOCT) scan quality, and peripapillary retinal nerve fiber layer thickness (RNFLT) measurements in healthy monkey eyes. Methods: In total, 83 healthy rhesus monkeys were included in this study (age range: 1.2–26.7 years). Peripapillary RNFLT was measured by SDOCT. An automated algorithm was used to count 100% of the axons and measure their cross-sectional area in postmortem optic nerve tissue samples ( N = 46). Simulation experiments were done to determine the effects of optical changes on measurements of RNFLT. An objective, fully-automated method ...

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    19. Anatomic vs. Acquired Image Frame Discordance in Spectral Domain Optical Coherence Tomography Minimum Rim Measurements

      Anatomic vs. Acquired Image Frame Discordance in Spectral Domain Optical Coherence Tomography Minimum Rim Measurements

      Purpose To quantify the effects of using the fovea to Bruch's membrane opening (FoBMO) axis as the nasal-temporal midline for 30° sectoral (clock-hour) spectral domain optical coherence tomography (SDOCT) optic nerve head (ONH) minimum rim width (MRW) and area (MRA) calculations. Methods The internal limiting membrane and BMO were delineated within 24 radial ONH B-scans in 222 eyes of 222 participants with ocular hypertension and glaucoma. For each eye the fovea was marked within the infrared reflectance image, the FoBMO angle (θ) relative to the acquired image frame (AIF) horizontal was calculated, the ONH was divided into 30°sectors using ...

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    20. Longitudinal Detection of Optic Nerve Head Changes by Spectral Domain Optical Coherence Tomography in Early Experimental Glaucoma

      Longitudinal Detection of Optic Nerve Head Changes by Spectral Domain Optical Coherence Tomography in Early Experimental Glaucoma

      Purpose. To determine if the detection of spectral domain optical coherence tomography (SDOCT) optic nerve head (ONH) change precedes the detection of Confocal Scanning Laser Tomography (CSLT) ONH surface, SDOCT retinal nerve fiber layer (RNFL), Scanning Laser Perimetry (SLP) and multifocal electroretinography (mfERG) change in 8 experimental glaucoma (EG) eyes. Methods. Both eyes from 8 monkeys were tested at least 3 times at baseline, and then every 2 weeks following laser-induced chronic unilateral IOP elevation. Event and trend-based definitions of onset in both the control and EG eyes for a total of 11 SDOCT neural and connective tissue, CSLT surface ...

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    21. Correlating Perimetric Indices With Three Nerve Fiber Layer Thickness Measures

      Correlating Perimetric Indices With Three Nerve Fiber Layer Thickness Measures

      PURPOSE: To determine which of three estimates of retinal nerve fiber layer thickness (RNFLT) correlate best with visual field sensitivity measured using standard automated perimetry (SAP). METHODS: Data were collected from 400 eyes of 209 participants enrolled in the Portland Progression Project. These individuals ranged from high-risk suspects to having non-end-stage glaucoma. In each eye, three measures of average RNFLT (spectral domain optical coherence tomography [SDOCT], scanning laser polarimetry [SLP], confocal scanning laser tomography [CSLT]) and SAP (Humphrey HFAII) were performed on the same day. Mean deviation (MD), mean sensitivity (MS), and pattern standard deviation (PSD) were linearized using the ...

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    22. Onset and Progression of Peripapillary Retinal Nerve Fiber Layer (RNFL) Retardance Changes Occur Earlier Than RNFL Thickness Changes in Experimental Glaucoma

      Onset and Progression of Peripapillary Retinal Nerve Fiber Layer (RNFL) Retardance Changes Occur Earlier Than RNFL Thickness Changes in Experimental Glaucoma

      Purpose. Longitudinal measurements of peripapillary RNFL thickness and retardance were compared in terms of time to reach onset of damage and time to reach a specific progression endpoint. Methods. A total of 41 rhesus macaques with unilateral experimental glaucoma (EG) each had three or more weekly baseline measurements in both eyes of peripapillary RNFL thickness (RNFLT) and retardance. Laser photocoagulation was then applied to the trabecular meshwork of one eye to induce chronic elevation of intraocular pressure and weekly imaging continued. Pairwise differences between baseline observations were sampled by bootstrapping to determine the 95% confidence limits of each measurement's ...

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    23. Relationship between Orbital Optic Nerve Axon Counts and Retinal Nerve Fiber Layer Thickness Measured by Spectral Domain Optical Coherence Tomograph

      Relationship between Orbital Optic Nerve Axon Counts and Retinal Nerve Fiber Layer Thickness Measured by Spectral Domain Optical Coherence Tomograph

      Purpose: To determine the relationship between total optic nerve axon counts and peripapillary retinal nerve fiber layer thickness (RNFLT) measured in vivo by spectral domain optical coherence tomography (SDOCT). Methods: Twenty-two rhesus macaques had three or more baseline measurements in both eyes of peripapillary RNFLT made by SDOCT (Spectralis, Heidelberg Engineering GmbH). Laser photocoagulation was then applied to the trabecular meshwork of one eye to induce chronic unilateral IOP elevation. SDOCT measurements of RNFLT continued approximately every two weeks until the pre-defined study endpoint was reached in each animal. At endpoint, animals were sacrificed and the optic nerve was sampled ...

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    24. Spectral-Domain Optical Coherence Tomography Enhanced Depth Imaging of the Normal and Glaucomatous Nonhuman Primate Optic Nerve Head

      Spectral-Domain Optical Coherence Tomography Enhanced Depth Imaging of the Normal and Glaucomatous Nonhuman Primate Optic Nerve Head
      Purpose. To test whether the enhanced depth imaging (EDI) modality improves anterior and posterior lamina cribrosa surface (ALCS and PLCS) visibility compared with conventional spectral-domain optical coherence tomography (SD-OCT). Methods. Conventional and EDI SD-OCT scans were obtained 30 minutes after IOP was manometrically lowered to 10 mm Hg in both eyes of 14 nonhuman primates (NHPs) with unilateral experimental glaucoma (EG). Thirteen horizontal and seven vertical radial B-scans of each SD-OCT data set were delineated by one operator masked to image type. Delineated ALCS and PLCS points were projected to 1 of 100 equal-sized subregions of the neural canal opening ...
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    Longitudinal Change Detected by Spectral Domain Optical Coherence Tomography in the Optic Nerve Head and Peripapillary Retina in Experimental Glaucoma Deformation of the Rodent Optic Nerve Head and Peripapillary Structures during Acute Intraocular Pressure Elevation The Effect of Acute Intraocular Pressure Elevation on the Monkey Optic Nerve Head As Detected by Spectral Domain Optical Coherence Tomography Spectral Domain Optical Coherence Tomography (SDOCT) Enhanced Depth Imaging (EDI) of the Normal and Glaucomatous Non-human Primate (NHP) Optic Nerve Head (ONH) Spectral-Domain Optical Coherence Tomography Enhanced Depth Imaging of the Normal and Glaucomatous Nonhuman Primate Optic Nerve Head Onset and Progression of Peripapillary Retinal Nerve Fiber Layer (RNFL) Retardance Changes Occur Earlier Than RNFL Thickness Changes in Experimental Glaucoma The truth about invisible posterior vitreous structures Increased Macrophage-like Cell Density in Retinal Vein Occlusion as Characterized by en Face Optical Coherence Tomography The Influence of Eyelid Position and Environmental Conditions on the Corneal Changes in Early Postmortem Interval: A Prospective, Multicentric OCT Study The Use of Optical Coherence Tomography for Gross Examination and Sampling of Fixed Breast Specimens: A Pilot Study The Role of Widefield and Ultra Widefield Optical Coherence Tomography in the Diagnosis and Management of Vitreoretinal Diseases Acute Idiopathic Blind Spot Enlargement Syndrome-New Perspectives in the OCT Era