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Progrès dans les méthodes diagnostiques du déficit en cellules souches limbiques. Apport de la microscopie confocale et de la tomographie en cohérence optique
摘要： The limbus is the anatomical and functional barrier between corneal and conjunctival epithelia. It is characterized by presence of the limbal stem cell niche which allows corneal homeostasis to be maintained. Limbal stem cell deficiency is characterized by a dual process: insufficient regeneration of corneal epithelium, which cannot therefore assure its function of physiological support, associated with corneal invasion by conjunctival proliferation. Diagnosis is currently made via routine clinical examination, corneal impression cytology and in vivo confocal microscopy (IVCM). Slit lamp examination shows abnormal limbal anatomy, thin and irregular epithelium with late fluorescein staining, and superficial vascularization. With its high resolution, IVCM allows identification of limbal and corneal epithelial changes at a cellular level in en face views, parallel to the corneal surface, but with a restricted viewing field of the corneal surface. It shows a poor transition between the corneal and conjunctival epithelia, associated with a loss of the normal corneal epithelial stratification, low basal cell and sub-basal nerve plexus densities, even with sub-epithelial fibrosis. Optical coherence tomography in central cornea and at the limbus, with scans in different orientations, allows a quick, global and non-invasive analysis of normal eyes and those with limbal stem cell deficiency. It shows a thin limbal epithelium, lacking normal thickening, featuring absence of stromal undulations and limbal crypts in cross-sections and sections parallel to the limbus, lack of visible limbal crypts in en face sections, loss of clear transition between the hyporeflective corneal epithelium and the hyperreflective conjunctival epithelium, and hyperreflective sub-epithelial fibrosis.
关键词： Limbal stem cell deficiency,Limbus,Optical coherence tomography,In vivo confocal microscopy
更新于2025-09-23 15:23:52
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Vascular and structural alterations of the choroid evaluated by optical coherence tomography angiography and optical coherence tomography after half-fluence photodynamic therapy in chronic central serous chorioretinopathy
摘要： Purpose To concurrently evaluate the effect of half-fluence photodynamic therapy (hf PDT) on choriocapillaris (CC) perfusion and choroidal structure in chronic central serous chorioretinopathy (CSC). Methods This prospective study included 48 eyes of 41 patients with chronic CSC. Enhanced depth imaging optical coherence tomography and optical coherence tomography angiography (OCTA) images were analyzed. Choroidal area (CA), luminal area (LA), and stromal area (SA) were computed using Image J software. Results One month after hf-PDT, total CA decreased to 1.312 mm2 from 1.490 mm2 (p < 0.001), LA decreased to 0.981 mm2 from 1.097 mm2 (p < 0.001), and SA decreased to 0.331 mm2 from 0.393 mm2 (p < 0.001). In OCTA, the CC flow in the eyes with CSC (17.75 mm2) was statistically significantly lower than the fellow eyes (18.93 mm2) at the baseline visit (p < 0.001). After hf-PDT, the flow in the choriocapillaris statistically significantly increased to 18.81 mm2 at the first month (p = 0.02). Conclusions OCTA proves that after hf-PDT a significant increase in CC perfusion occurred at first month. The decrease of the luminal areas in enhanced depth imaging optical coherence tomography is mainly due to a decrease in large-caliber vessels, which indicates that hf-PDT has an effect on larger choroidal vessels and spares CC flow.
关键词： Chronic central serous chorioretinopathy,Optical coherence tomography angiography,Half-fluence photodynamic therapy,Choriocapillaris perfusion
更新于2025-09-23 15:23:52
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Fundus autofluorescence and spectral domain optical coherence tomography as predictors for long-term functional outcome in rhegmatogenous retinal detachment
摘要： Purpose To detect pre- and postoperative retinal changes in fundus autofluorescence (AF) and spectral domain optical coherence tomography (SD-OCT) and to correlate these with functional outcome in patients with primary rhegmatogenous retinal detachment (RRD). Methods A prospective, 30-month study of patients operated with 25-gauge vitrectomy for primary RRD. Patients were examined preoperatively and after 6 and 30 months, using ultrawide-field AF images (UWFI) (Optos 200Tx) and SD-OCT (Topcon 3D OCT-2000) imaging. Results Of 84 patients (84 eyes) included at baseline, 100.0 and 86.9% were re-examined at month 6 and 30, respectively. Preoperative findings such as macular attachment, detachment > 750 μm from foveola, lack of intraretinal separation, and subfoveal elevation ≤ 500 μm were all associated with better BCVA at months 6 and 30. Postoperative disruption of the photoreceptor layer was associated with poor BCVA at month 6 (p < 0.001) but not at month 30. At baseline, AF-demarcation of RRD was demonstrated by a hyperfluorescent edge in 92.0% and was associated with visual impairment at months 6 (p = 0.003) and 30 (p = 0.003). Visual outcome at month 30 was good (≤ 0.3 logMAR (≥ 20/40 Snellen)), regardless of the preoperative, macular status. However, with significantly better visual outcome in patients with macula attachments versus partly or totally macular detachments (p < 0.001). Conclusion Fundus AF and SD-OCT is able to identify retinal reestablishment up to 30 months after primary RRD, with good correlation to BCVA. These findings emphasize the importance of long-term studies for final visual recovery.
关键词： Fundus autofluorescence,Rhegmatogenous retinal detachment,Long-term outcome,Vitrectomy,Visual outcome,Optical coherence tomography
更新于2025-09-23 15:23:52
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Impact of segmentation density on spectral domain optical coherence tomography assessment in Stargardt disease
摘要： Purpose Automated spectral domain optical coherence tomography (SD-OCT) segmentation algorithms currently do not perform well in segmenting individual intraretinal layers in eyes with Stargardt disease (STGD). We compared selective B-scan segmentation strategies for generating mean retinal layer thickness and preserved area data from SD-OCT scans in patients with STGD1. Methods Forty-five eyes from 40 Stargardt patients were randomly selected from the ongoing Natural History of the Progression of Atrophy Secondary to Stargardt Disease (ProgStar) study. All eyes underwent SD-OCT using a standard macular volume consisting of 1024 × 49 equally spaced B-scans within a 20 × 20 degree field centered on the fovea. All 49 B-scans were segmented manually to quantify total retina, outer nuclear layer (ONL), photoreceptor inner segments, photoreceptor outer segments (OS), and retinal pigment epithelial layer (RPE). Mean thickness and total area were generated using all 49 B-scans (spaced 122 μm apart), 25 B-scans (every other B-scan, spaced 240 μm apart), 17 B-scans (every third scan, 353 μm apart), and 13 B-scans (every fourth scan, 462 μm apart), as well as by using an Badaptive^ method where a subset (minimum 25 B-scans) of B-scans that the grader deemed as significantly different from adjacent B-scans were utilized. Mean absolute and percentage errors were calculated for macular thickness and area of different retinal layers for the different B-scan subset selection strategies relative to using all 49 B-scans, which was considered the reference or ground truth. Results Mean thickness and area measurements were significantly different for any regularly spaced reduction in B-scan density relative to the ground truth. When an adaptive approach was applied using a minimum of half the scans, the differences relative to ground truth were no longer significantly different. The mean percent differences for the area and thicknesses of the various layers ranged from 0.02 to 33.66 (p < 0.05 for all comparisons) and 0.44 to 7.24 (p > 0.05) respectively. Conclusion Manual segmentation of a subset of B-scans using an adaptive strategy can yield thickness and area measurements of retinal sublayers comparable to the reference ground truth derived from using all B-scans in the volume. These results may have implications for increasing the efficiency of SD-OCT grading strategies in clinical trials for STGD and other related macular degenerative disorders.
关键词： Stargardt,Segmentation density,Spectral domain optical coherence tomography,Retinal layers
更新于2025-09-23 15:23:52
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Advances in imaging and molecular diagnostics of ocular tuberculosis and selected observations from the Collaborative Ocular Tuberculosis Study (COTS)
摘要： Introduction: Ocular tuberculosis (TB) is a rare extra-pulmonary manifestation with protean clinical manifestations. Ocular TB as a cause of potentially blinding disease has been recently recognized by ophthalmologists as well as pulmonologists. In the past decade, there has been a great leap in our understanding of the disease pathogenesis, clinical and imaging features, as well as therapeutic challenges and disease complications. Areas covered: In this expert review, an emphasis has been laid on the recent advances in ocular imaging including wide-field fundus imaging, fluorescein angiography and autofluorescence, enhanced-depth optical coherence tomography, optical coherence tomography angiography, among others, as well as progress in the field of diagnostics such as polymerase chain reaction and other nucleic acid amplification tests. Findings from the Collaborative Ocular Tuberculosis Study (COTS), a multicentric study on ocular TB, have been explained in details. Expert opinion: Due to rapid advances in the field of fundus imaging and laboratory testing, it has become possible to recognize the pathological alterations observed in ocular TB. With further research, it may be possible to generate a consensus on the diagnosis and management of this entity in the future.
关键词： Tuberculosis,optical coherence tomography,choroiditis,fluorescein angiography,serpiginous-like choroiditis,indocyanine green angiography,uveitis
更新于2025-09-23 15:23:52
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Small HDL subclass is associated with coronary plaque stability: An optical coherence tomography study in patients with coronary artery disease
摘要： BACKGROUND: The role of high-density lipoprotein (HDL) subclasses in atherosclerotic diseases remains an open question. Previous clinical trials have attempted to explore the predictive effect of HDL subspecies on cardiovascular risk. However, no studies have assessed the connections between these subclasses and characteristics of plaque microstructure. OBJECTIVE: To investigate the relationship of HDL subclasses and coronary plaque stability assessed by optical coherence tomography (OCT). METHODS: Morphological characteristics of 160 nontarget lesions from 85 patients with coronary artery disease were assessed by OCT. HDL subclass profiles were analyzed using nondenaturing polyacrylamide gel electrophoresis. RESULTS: The plasma levels of small HDL subclass (percentage or concentration) were found to be positively associated with fibrous cap thickness (r = 0.232, P = .007; r = 0.243, P = .005) and negatively with maximum lipid arc (r = -0.240, P = .005; r = -0.252, P = .003) and lipid core length (r = -0.350, P < .001; r = -0.367, P < .001). Multivariate logistic regression analysis showed the small HDL subclass (percentage or concentration) (odds ratio [OR]: 0.457, 95% confidence interval [CI]: 0.214–0.974, P = .043; OR: 0.438, 95% CI: 0.204–0.938, P = .034) to be an independent factor in predicting OCT-detected thin-cap fibroatheroma of nontarget lesions. CONCLUSION: High levels of small HDL are associated with coronary nontarget plaque stability. Our findings suggest that the small HDL subtype might represent the atheroprotective activity of HDL.
关键词： Atherosclerosis,High-density lipoprotein,Optical coherence tomography,Plaque stability
更新于2025-09-23 15:23:52
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New ellipsometric approach for determining small light ellipticities
摘要： Control of the coherent light polarization is always one of the important topics in laser physics and engineering. We propose an exact ellipsometric method for investigation of coherent light with small ellipticity. Using compensators with phase retardations providing maximum measurement accuracy for the selected ellipticity range is suggested. The method allows us to avoid taking into account the interference of multiple internal reflections of coherent light. The accuracy of the method increases with decreasing of the compensator phase retardation. Using light with a given ellipticity, we have measured the ellipticity of the light in the range of 3.5×10?? to 5.0×10?3. The relative error of the ellipticity measuring in the range of 8.0×10?? to 5.0×10?3 turns out does not exceed 0.02.
关键词： Polarization,Ellipsometry,Coherence
更新于2025-09-23 15:23:52
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Polarimetric Interferometric SAR Change Detection Discrimination
摘要： A coherent change detection (CCD) image, computed from a geometrically matched, temporally separated pair of complex-valued synthetic aperture radar (SAR) image sets, conveys the pixel-level equivalence between the two observations. Low-coherence values in a CCD image are typically due to either some physical change in the corresponding pixels or a low signal-to-noise observation. A CCD image does not directly convey the nature of the change that occurred to cause low coherence. In this paper, we introduce a mathematical framework for discriminating between different types of change within a CCD image. We utilize the extra degrees of freedom and information from polarimetric interferometric SAR (PolInSAR) data and PolInSAR processing techniques to define a 29-dimensional feature vector that contains information capable of discriminating between different types of change in a scene. We also propose two change-type discrimination functions that can be trained with feature vector training data and demonstrate change-type discrimination on an example image set for three different types of change. Furthermore, we also describe and characterize the performance of the two proposed change-type discrimination functions by way of receiver operating characteristic curves, confusion matrices, and pass matrices.
关键词： polarimetric interferometric synthetic aperture radar (PolInSAR),H/A/α filter,probabilistic feature fusion (PFF) model,feature vector,Coherent change detection (CCD),optimum coherence (OC),H/A/α decomposition
更新于2025-09-23 15:23:52
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Spectral-domain optical coherence tomography foveal morphology as a prognostic factor for vision performance in congenital aniridia
摘要： Background: Patients with congenital aniridia usually have some degree of foveal hypoplasia, thus representing a limiting factor in the final visual acuity achieved by these patients. The purpose of this study was to analyze whether the foveal morphology assessed by spectral-domain optical coherence tomography may serve as a prognostic indicator for best-corrected visual acuity in congenital aniridia patients. Methods: Observational two-center study performed between January 2012 and March 2017 in the pediatric ophthalmology department at Vissum Alicante and Vissum Madrid, Spain. A total of 31 eyes from 19 patients with congenital aniridia were included. After a complete ophthalmological examination, a high-resolution spectral-domain optical coherence tomography with a three-dimensional scan program macular protocol was used. A morphological grading system of foveal hypoplasia was used varying from grade 1 in which there is a presence of a shallow foveal pit, extrusion of inner retinal layers, outer nuclear layer widening, and a presence of outer segment lengthening to grade 4 in which none of these processes occur. Results: No correlation between central, mid-peripheral, and peripheral macular thickness and logMAR best-corrected visual acuity was found. The presence of outer segment lengthening was associated with better best-corrected visual acuity with a median best-corrected visual acuity, 0.30 logMAR, whereas the absence of this morphologic feature was associated with poorer VA with a median best-corrected visual acuity of 0.61 logMAR (p < 0.001). Conclusion: Foveal hypoplasia morphology can predict the best-corrected visual acuity. Specifically, the morphologic optical coherence tomography feature that is related to a better best-corrected visual acuity in congenital aniridia patients is the presence of outer segment lengthening.
关键词： Congenital aniridia,spectral-domain optical coherence tomography,foveal hypoplasia
更新于2025-09-23 15:23:52
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Quantitative measurement of vascular density and flow using optical coherence tomography angiography (OCTA) in patients with central retinal vein occlusion: Can OCTA help in distinguishing ischemic from non-ischemic type?
摘要： Background: To evaluate microvascular changes and quantitative parameters in patients with central retinal vein occlusion (CRVO) by using optical coherence tomography angiography (OCTA) and finding difference between presumably ischemic and non ischemic CRVO. Methods: Patients with CRVO (31) and healthy control (20) were enrolled in this observational case control study. The OCTA was done for each patient and control subject. In macular area 2 images were taken for each eye (3 × 3 mm and 8 × 8 mm). The images were analyzed at three capillary plexuses (superficial and deep retinal capillary layers and choriocapillaris layer). Results: Thirty-one patients with CRVO (mean age 60.00 ± 13.72 years) and 20 healthy age/gender matched subjects (mean age 54.10 ± 12.33 years) were enrolled in this study (p = 0.095). The mean visual acuity of patients was 0.47 ± 0.54 LogMAR. Eyes with CRVO as compared with fellow eyes and control group showed significant reduction of flow in superficial (1.171 ± 0.262 vs. 1.362 ± 0.285 vs. 1.453 ± 0.105) and deep capillary plexus (1.042 ± 0.402 vs. 1.331 ± 0.315 vs. 1.526 ± 0.123) and choriocapillaris (1.206 ± 0.543 vs. 1.841 ± 0.308 vs. 1.966 ± 0.05) and vascular density in superficial (45.92 ± 4.2 vs. 50.99 ± 4.35 vs. 52.85 ± 2.99) and deep (48.03 ± 4.71 vs. 55.86 ± 3.81 vs. 58.2 ± 2.65) capillary plexuses. Some parameters (flow of both retinal capillary plexuses and parafoveal vascular density in deep plexus) showed significantly reduction in fellow eyes than control group. The parameters including flow [superficial (1.014 ± 0.264 vs. 1.279 ± 0.19) and deep (0.873 ± 0.442 vs. 1.152 ± 0.32) capillary plexuses and choriocapillaris (0.79 ± 0.327 vs. 1.424 ± 0.51)] and vascular density [superficial (44.24 ± 2.13 vs. 46.58 ± 4.13) and deep (45.28 ± 3.5 vs. 49.32 ± 3.94) capillary plexuses] were lower significantly in ischemic type than non ischemic CRVO. The most damaged parameter was flow in deep capillary plexus. The model with smallest Akaike information criterion and Bayesian information criterion was chosen as the best model. For easier calculation, we also calculated the reduced model. By choosing the threshold of 12.6, the formula [3.9 × F1S + 0.8 × F3S] can diagnose the presumably ischemic CRVO from non ischemic type with AUC of 0.84, sensitivity of 100% and specificity of 69%. (F1S: flow in the central 1 mm-radius-circle of superficial plexus and F3S: flow in the central 3 mm-radius-circle of superficial plexus). Conclusion and relevance: In CRVO patients, the OCTA can accurately evaluate changes in microvascular structures. It may help in differentiation ischemic CRVO from non-ischemic CRVO.
关键词： Ischemic,Non-ischemic,Central retinal vein occlusion,Optical coherence tomography angiography
更新于2025-09-23 15:23:52