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Impact of Microscope-Integrated OCT on Ophthalmology Resident Performance of Anterior Segment Surgical Maneuvers in Model Eyes
摘要： PURPOSE. The integration of swept-source optical coherence tomography (SS-OCT) into the operating microscope enables real-time, tissue-level three-dimensional (3D) imaging to aid in ophthalmic microsurgery. In this prospective randomized controlled study, we evaluated the impact of SS microscope-integrated OCT (MI-OCT) on ophthalmology residents’ performance of ophthalmic microsurgical maneuvers. METHODS. Fourteen ophthalmology residents from a single institution were strati?ed by year of training and randomized to perform four anterior segment surgical maneuvers on porcine eyes with (MI-OCTt) or without intraoperative OCT guidance. Subsequently, both groups repeated the same maneuvers without MI-OCT feedback to test whether initial MI-OCT experience affected subsequent surgical performance. Finally, the MI-OCT(cid:2) group was crossed over and allowed to repeat the same maneuvers with direct MI-OCT guidance. Each resident completed a survey at the completion of the study. RESULTS. With direct MI-OCT feedback, residents demonstrated enhanced performance in depth-based anterior segment maneuvers (corneal suture passes at 50% and 90% depth and corneal laceration repair) compared with the residents operating without MI-OCT. Microscope-integrated OCTt residents continued to outperform the controls when both groups subsequently operated without MI-OCT. For clear corneal wound geometry, there was no statistically signi?cant effect of MI-OCT as applied in this study. Overall, the resident surgeons rated their subjective experience of using MI-OCT very favorably. CONCLUSIONS. Microscope-integrated OCT feedback enhances performance of ophthalmology residents in select anterior segment surgical maneuvers. Microscope-integrated OCT represents a valuable tool in the surgical education of ophthalmology residents.
关键词： resident education,optical coherence tomography,ophthalmologic surgical procedures
更新于2025-09-10 09:29:36
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Relationship Between Presumptive Inner Nuclear Layer Thickness and Geographic Atrophy Progression in Age-Related Macular Degeneration
摘要： To analyze inner retinal changes in patients with geographic atrophy (GA) secondary to age-related macular degeneration and identify morphological cues for progression. A total of 100 eyes with GA were assessed in this longitudinal, observational case series. Patients with GA and absent confounding pathology were compared with age-matched controls. The retinal layers on spectral-domain optical coherence tomography, acquired in tracking mode, were segmented manually on central scans through the fixation point. Zones of GA were defined based on choroidal signal enhancement from retinal pigment epithelium loss. An area of unaffected temporal retina was used for comparison. Progression of GA was quantified with fundus autofluorescence. We analyzed 41 eyes of 41 patients (mean age 79.2 ± 6.7 years). In areas of GA, the layer representing the inner nuclear layer (INL) in healthy retina was increased in thickness. Thickness of this presumptive INL was inversely correlated with best-corrected visual acuity (r = ?0.48, P < 0.01). The presumptive INL thickness increase in atrophic areas was less marked in eyes with foveal sparing. Increased INL thickness in areas adjacent to GA was associated with a higher progression rate. Optical coherence tomography findings demonstrate that atrophy of the retinal pigment epithelium-photoreceptor complex in GA is associated with an increase of thickness of the presumptive INL, presumably caused by remodeling of the degenerating retina. Similar alterations in the retina adjacent to areas clinically affected by GA were associated with higher atrophy progression rates.
关键词： geographic atrophy,retinal segmentation,optical coherence tomography,autofluorescence,disease progression
更新于2025-09-10 09:29:36
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The Feasibility of Spectral-Domain Optical Coherence Tomography Grading of Anterior Chamber Inflammation in a Rabbit Model of Anterior Uveitis
摘要： PURPOSE. To determine the feasibility and accuracy of spectral-domain optical coherence tomography (SD-OCT) based grading of anterior chamber cell, using aqueous sampling as a standard, in a rabbit model of anterior uveitis. METHODS. Adult Dutch-belted rabbits were preimmunized with M. tuberculosis (Tb) H37RA antigen, 1 week prior to induction of anterior uveitis with an intracameral injection of Tb antigen. The anterior chamber was imaged with SD-OCT, followed by a slit lamp examination. Two independent, trained graders recorded their estimate of anterior chamber cell count using the Standardization of Uveitis Nomenclature (SUN) scores for each eye prior to performing an anterior chamber tap to determine the aqueous cell density using a hemocytometer. Using the aqueous cell density as a standard, correlation with SD-OCT counts were compared to those with SUN scores. RESULTS. Overall, SD-OCT correlated well with the hemocytometer counts (Spearman coef?cient ? 0.53, P < 0.001) compared with SUN grading and hemocytometer counts (Spearman coef?cient ? 0.02, P ? 0.88). The correlation improved to 0.65 (P < 0.001) when we excluded eyes with corneal thickness ? 470 lm. Eyes with corneal thickness ? 470 lm exhibited the greatest degree of ocular in?ammation and corneal opacity. CONCLUSIONS. In our rabbit model, SD-OCT grading of anterior chamber cell correlated signi?cantly better with aqueous cell counts, compared to traditional slit lamp grading. Spectral-domain optical coherence tomography grading of anterior chamber cell may be a good alternative to SUN grading. Although SUN grading remains the clinical gold standard, alternative quantitative methods to assess ocular in?ammation could provide insight into disease mechanism and aid in measuring treatment response.
关键词： anterior chamber cell,SUN grading,optical coherence tomography,anterior chamber sampling,uveitis
更新于2025-09-10 09:29:36
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Posterior Eye Shape Measurement With Retinal OCT Compared to MRI
摘要： PURPOSE. Posterior eye shape assessment by magnetic resonance imaging (MRI) is used to study myopia. We tested the hypothesis that optical coherence tomography (OCT), as an alternative, could measure posterior eye shape similarly to MRI. METHODS. Macular spectral-domain OCT and brain MRI images previously acquired as part of the Singapore Epidemiology of Eye Diseases study were analyzed. The right eye in the MRI and OCT images was automatically segmented. Optical coherence tomography segmentations were corrected for optical and display distortions requiring biometry data. The segmentations were ?tted to spheres and ellipsoids to obtain the posterior eye radius of curvature (Rc) and asphericity (Qxz). The differences in Rc and Qxz measured by MRI and OCT were tested using paired t-tests. Categorical assignments of prolateness or oblateness using Qxz were compared. RESULTS. Fifty-two subjects (67.8 6 5.6 years old) with spherical equivalent refraction from t0.50 to (cid:2)5.38 were included. The mean paired difference between MRI and original OCT posterior eye Rc was 24.03 6 46.49 mm (P ? 0.0005). For corrected OCT images, the difference in Rc decreased to (cid:2)0.23 6 2.47 mm (P ? 0.51). The difference between MRI and OCT asphericity, Qxz, was (cid:2)0.052 6 0.343 (P ? 0.28). However, categorical agreement was only moderate (j ? 0.50). CONCLUSIONS. Distortion-corrected OCT measurements of Rc and Qxz were not statistically signi?cantly different from MRI, although the moderate categorical agreement suggests that individual differences remained. This study provides evidence that with distortion correction, noninvasive of?ce-based OCT could potentially be used instead of MRI for the study of posterior eye shape.
关键词： asphericity,optical coherence tomography,magnetic resonance imaging,myopia
更新于2025-09-10 09:29:36
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Glaucoma Increases Retinal Surface Contour Variability as Measured by Optical Coherence Tomography
摘要： We investigated the feasibility of glaucoma detection by measuring retinal surface contour variability (RSCV) using optical coherence tomography (OCT). The peripapillary region in one eye of each participant was scanned over an 8 3 8 mm area with a swept source OCT prototype. The retinal surface contour was sampled at approximately 1.5- to 3.5-mm radius circles centered on the optic nerve head. The RSCV is defined as the average log value within a middle spatial frequency band of the Fourier transform to the elevation profile of the inner retinal surface. The spatial frequency band was optimized to distinguish glaucoma from normal. Nerve fiber layer thickness (NFLT) was sampled around a 1.7-mm radius circle. Glaucoma severity was assessed by automated static perimetry. We enrolled 17 glaucomatous eyes and 17 healthy eyes. A great majority of the glaucoma group were in the early stage (visual field mean deviation average (cid:2)2.48 6 3.73 dB). Significant differences were found for RSCV between glaucoma and control eyes (P < 0.003) at all radii. The area under the receiver operating characteristic curve (AROC ? 0.90) of RSCV was best at the 3.5-mm radius. This was not significantly better than NFLT (AROC ? 0.84). With the 99% specificity, the glaucoma detection sensitivity was 53% for RSCV and 29% for NFLT (P ? 0.13). Retinal surface contour variability was significantly increased in glaucoma patients. The diagnostic accuracy of RSCV was equal to NFLT in early glaucoma. Since the RSCV detects small-scale focal damage and the average NFLT measures global damage, they provide different diagnostic information that may be synergistic.
关键词： optical coherence tomography,glaucoma,nerve fiber layer,retinal surface contour variability
更新于2025-09-10 09:29:36
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Retinal Blood Flow Response to Hyperoxia Measured With En Face Doppler Optical Coherence Tomography
摘要： PURPOSE. To use multiplane en face Doppler optical coherence tomography (OCT) to measure the change in total retinal blood ?ow (TRBF) in response to hyperoxia. METHODS. One eye of each healthy human participant (n ? 8) was scanned with a commercial high-speed (70-kHz) spectral OCT system. Three repeated scans were captured at baseline and after 10 minutes of oxygen (hyperoxia) by open nasal mask. The procedure was performed twice on day 1 and once more on day 2. Blood ?ow of each vein was estimated using Doppler OCT at an optimized en face plane. The TRBF was summed from all veins at the optic disc. The TRBF hyperoxic response was calculated as the TRBF percent change from baseline. RESULTS. Participants experienced a 23.6% 6 10.7% (mean 6 standard deviation [SD]) decrease (P < 0.001, paired t-test) in TRBF during hyperoxia. The within-day repeatability of baseline TRBF was 4.1% and the between-day reproducibility was 10.9% coef?cient of variation (CV). Between-grader reproducibility was 3.9% CV. The repeatability and reproducibility (pooled SD) of hyperoxic response were 6.1% and 6.4%, respectively. CONCLUSIONS. The multiplane en face Doppler OCT algorithm was able to detect, in all participants, a decreased TRBF in response to hyperoxia. The response magnitude for each participant varied among repeated trials, and the averaging of multiple trials was helpful in establishing the individual response. This technique shows good potential for the clinical investigation of vascular autoregulation.
关键词： hyperoxia,en face doppler optical coherence tomography,total retinal blood ?ow
更新于2025-09-10 09:29:36
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Spectral-Domain Optical Coherence Tomography Findings in Neurofibromatosis Type 2
摘要： Neurofibromatosis type 2 (NF2) is an autosomal-dominant disease, characterized by bilateral vestibular schwannomas, multiple central nervous system (CNS) tumors, skin tumors, and juvenile cataract. The present study assessed retinal abnormalities using spectral-domain optical coherence tomography (SD-OCT) in a case series of NF2 patients. METHODS. Nine NF2 patients from the neurofibromatosis outpatient reference center of the Federal University of Minas Gerais, in Brazil, were submitted to a complete anamnesis and a detailed ophthalmic evaluation, including SD-OCT, to detect retinal lesions. RESULTS. Of the nine NF2 patients evaluated, five had an early onset (<20 years) of NF2, and four patients had a late onset (>20 years) of symptoms. SD-OCT scans revealed retinal abnormalities in every patient with early onset (EOS) and in two patients with late onset (LOS) of the disease. In the EOS group, SD-OCT scans revealed flame-shaped epiretinal membranes (ERM) with peculiar characteristics in four eyes of three patients. Two patients had fine undulations of the inner retinal surface with a subtle ERM. Retinal hamartomas were present in four eyes of three patients with EOS; in two eyes, they were subclinical and were detected only by SD-OCT scans. In two patients with LOS and one patient with EOS, SD-OCT scans revealed retinal tufts of a nerve fiber layer. CONCLUSIONS. SD-OCT revealed ERM in most patients with NF2, therefore it may be a valuable exam for evaluating NF2 patients. Epiretinal membranes in NF2 has unique features, distinguishing it from idiopathic ERM or membranes associated with other diseases. We suggest that flame-shaped ERM seems to be specific for NF2 and that ERM can be considered as an important diagnostic sign of NF2.
关键词： epiretinal membrane,neurofibromatosis type 2,vestibular schwannoma,optical coherence tomography,retina
更新于2025-09-10 09:29:36
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Optical Coherence Tomography and the Development of Antiangiogenic Therapies in Neovascular Age-Related Macular Degeneration
摘要： To explain the pivotal role optical coherence tomography (OCT) imaging had in the development of antiangiogenic therapies for the treatment of neovascular age-related macular degeneration (nvAMD). A historical literature review was combined with personal perspectives from the introduction of OCT imaging and the early clinical use of vascular endothelial growth factor (VEGF) inhibitors. At the time that OCT emerged, the gold standard for imaging of nvAMD was fluorescein angiography (FA), a time-consuming, dye-based, invasive technique that provided en face images of the retina and was used to characterize leakage, perfusion status, and the types of macular neovascularization (MNV). In comparison, OCT imaging was a fast, safe, noninvasive technique that complemented FA imaging by providing cross-sectional images of the macula. OCT was able to visualize and quantify the macular fluid that was associated with the presence of excess VEGF, which was identified by intraretinal fluid, subretinal fluid, and fluid under the retinal pigment epithelium (RPE). Clinicians quickly appreciated the benefits of OCT imaging for following macular fluid after anti-VEGF therapy. By observing the qualitative and quantitative changes in macular fluid depicted by OCT imaging, clinicians were empowered to compare anti-VEGF drugs and move from fixed-dosing regimens to patient-specific dosing strategies requiring fewer injections. Optical coherence tomography imaging was adopted as a VEGF-meter, a method to detect excess VEGF, and evolved to become the gold standard imaging strategy for diagnosing nvAMD, assessing treatment responses to anti-VEGF drugs, deciding when to re-treat, and evaluating disease progression.
关键词： neovascularization,anti-vascular endothelial growth factor,exudation,optical coherence tomography,antiangiogenesis
更新于2025-09-10 09:29:36
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Valley coherent exciton-polaritons in a monolayer semiconductor
摘要： Two-dimensional transition metal dichalcogenides (TMDs) provide a unique possibility to generate and read-out excitonic valley coherence using linearly polarized light, opening the way to valley information transfer between distant systems. However, these excitons have short lifetimes (ps) and efficiently lose their valley coherence via the electron-hole exchange interaction. Here, we show that control of these processes can be gained by embedding a monolayer of WSe2 in an optical microcavity, forming part-light-part-matter exciton-polaritons. We demonstrate optical initialization of valley coherent polariton populations, exhibiting luminescence with a linear polarization degree up to 3 times higher than displayed by bare excitons. We utilize an external magnetic field alongside selective exciton-cavity-mode detuning to control the polariton valley pseudospin vector rotation, which reaches 45° at B = 8 T. This work provides unique insight into the decoherence mechanisms in TMDs and demonstrates the potential for engineering the valley pseudospin dynamics in monolayer semiconductors embedded in photonic structures.
关键词： Exciton-polaritons,Valley pseudospin dynamics,TMDs,Microcavity,Valley coherence
更新于2025-09-10 09:29:36
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Improving visualization and quantitative assessment of choriocapillaris with swept source OCTA through registration and averaging applicable to clinical systems
摘要： Choriocapillaris (CC) visualization and quantification remains challenging. We propose an innovative three-step registration and averaging approach using repeated swept source optical coherence tomography angiography (SS-OCTA) scans to conduct automatic quantitative assessment on CC. Six subjects were enrolled, each imaged at several locations with SS-OCTA from macular to equatorial regions using 3 mm × 3 mm scanning pattern. Five repeated volumes were collected for each subject. The complex optical microangiography (OMAG) algorithm was applied to identify blood flow in CC slab. An automatic three-step registration of translation, affine and B-Spline was applied to en face OCTA images of CC, followed with averaging. A fuzzy clustering approach was used to segment vasculature and flow deficits from the averaged images. The improvement in visualization of CC was evaluated and the average intercapillary distance was estimated by calculating the averaged capillary lumen spacing. A series of quantitative indices of flow deficit density, number, size, complexity index and aspect ratio index (FDD, FDN, FDS, FDCI and FDARI) were designed and validated with the increase of repeated scan numbers for averaging. Quantitative assessment was applied and compared on CC in macular and equatorial regions. The intercapillary distance was observed to be around 24 μm at macula and increased toward equatorial regions. All five quantitative indices (FDD, FDN, FDS, FDCI and FDARI) showed significant changes with multiple averaging and tend to become stable with repeated number of 4. Our proposed registration and averaging algorithm significantly improved the visualization of CC with SS-OCTA. The designed five indices for CC provide more options in the quantitative assessment of CC and are of great potentials in assisting the understanding of disease pathology, early diagnosis and treatment monitoring.
关键词： quantitative assessment,optical coherence tomography angiography,choriocapillaris,averaging,registration
更新于2025-09-10 09:29:36