Structural Optical Coherence Tomography Research Articles

Rod and Cone Function Measured Objectively by Chromatic Pupil Campimetry Show a Different Preservation Between Distinct Genotypes in Retinitis Pigmentosa.

Verifying whether specific genotypes causing retinitis pigmentosa (RP) show differences in the preservation of rod and cone function measured by chromatic pupil campimetry (CPC). Sixty-three RP eyes (37 male, 14-58 years) were measured using CPC with specific photopic and scotopic protocols, and the relative maximal constriction amplitudes and latencies to constriction onset were analyzed per genotype (RP due to variants in EYS, n = 14; PDE6A, n = 10; RPE65, n = 15; USH2A, n = 10; and RPGR, n = 14). Correlation analyses between the pupillary responses were performed with age, full-field stimulus threshold (FST), and optical coherence tomography (OCT) for cones and rods, respectively, to the genotype. Pupillary responses were most severely reduced in RPE65-RP. Patients with disease-associated variants in EYS and USH2A were accompanied with better-preserved rod function compared with the other subgroups, reaching statistical significance between EYS and RPE65. Cone function was statistically significantly correlated with age in USH2A-RP with an annual decline of 2.4%. Correlations of pupillary responses were found with FST but barely with the ellipsoid zone area in OCT. Latency was significantly more prolonged in RPE65-RP compared with the other genotypes for cones. Rod and cone function measured objectively by CPC showed a different preservation between genotypes in RP. However, heterogeneity inside the same genotype was present. CPC data correlated with FST, but structural OCT parameters seem to be limited indicators for photoreceptor function in RP. Prolonged time dynamics for cones in RPE65 mutations suggest an impact on cone processing and might provide additional information in the evaluation of therapy effects.

Subclinical Angioid Streaks with Pseudodrusen: A New Phenotype of Age-Related Macular Degeneration.

To describe subclinical angioid streaks (AS) as a frequent, peculiar age-related macular degeneration (AMD) phenotype, comparing features of eyes with subclinical AS with those of eyes with AMD without AS. This was a retrospective, observational study. Among a patient cohort with AMD, we selected patients without known causes for AS whose eyes showed signs of angioid streaks (AS) on structural optical coherence tomography (OCT) but not on fundus examination. Selected OCT features of AS were Bruch's membrane (BM) breaks and large BM dehiscences. Among 543 eyes of 274 patients with AMD (mean ± standard deviation: 82 ± 7years), 73 eyes of 46 patients (81 ± 7years; p = 0.432) showed AS features on OCT (OCT AS) that were not visible on fundus examination. Estimated prevalence of subclinical age-related AS was 13.4% (95% confidence interval 10.3-16.3%) in this AMD population. Fifty-three eyes (73%) with AS features were affected by peripapillary atrophy, often with a "petaloid-like" pattern, similar to typical features of AS disease. Almost all cases (97%) presented reticular pseudodrusen (RPD), with (41%) or without (59%) drusen showing a significant difference in RPD prevalence in OCT AS eyes in comparison to AMD eyes without subclinical AS using generalized estimating equations (P < 0.001). Among the 73 subclinical AS cases, 71 were affected by late AMD (57 with macular neovascularization, 14 with geographic atrophy), showing a more advanced AMD stage in comparison with AMD eyes without subclinical AS (P < 0.001). The following OCT features were disclosed: BM breaks in 100% of cases and BM dehiscences in 37%. Subclinical AS in eyes with AMD is a peculiar phenotype of the disease, with features suggesting a primary involvement of Bruch's membrane and clinical similarities with mild, late-onset pseudoxanthoma elasticum.

Spotlight on Lattice Degeneration Imaging Techniques.

Lattice degeneration (LD), routinely diagnosed with indirect ophthalmoscopy, is one of the most common and clinically significant peripheral retinal findings. In this review, we have summarized the data on currently available imaging techniques which help to improve diagnosis and our understanding of LD pathogenesis. Ultra-wide field imaging provides reliable color fundus capturing for the primary diagnosis of LD and may also be used as a screening tool. Wide-field imaging can be used for targeted documentation of LD lesions using true colors and with minimal optical distortions. Information on the status of the vitreoretinal interface, including detection of retinal holes, detachments, and vitreous tractions, can be obtained with peripheral structural optical coherence tomography (OCT) or scanning laser ophthalmoscopy in retro-mode. These techniques clarify the associated risks of rhegmatogenous retinal detachment. Fundus autofluorescence can provide details on atrophic changes. However, the risk of retinal detachment by means of this technique requires further investigation. OCT angiography may be successfully performed for some lesions. Taken together, OCT and OCT angiography demonstrate thinning of the choroid, alteration of local choroidal microcirculation, and, in severe lesions, involvement of the sclera. OCT angiography confirms loss of retinal microcirculation within LD lesion, which was previously shown with fluorescein angiography. In conclusion, despite relatively simple primary diagnosis, imaging of LD lesions remains challenging due to their peripheral localization. However, several new strategies, including ultra-wide field imaging, peripheral OCT, and scanning laser ophthalmoscopy, make LD imaging possible on a routine basis, improving diagnosis and understanding of LD pathogenesis.

Retinal neurodegeneration in age-related macular degeneration.

Age-related macular degeneration (AMD) is a complex and multifactorial disease characterized by the damage of the unit comprised of the photoreceptors, retinal pigment epithelium (RPE), Bruch's membrane, and choriocapillaris. Although the outer retina appears to be mainly affected in this disorder, several evidences exhibit that also the inner retina may be impaired. In this review we will provide a description of the prominent histologic and imaging findings suggesting an inner retinal loss in these eyes. In details, structural optical coherence tomography (OCT) technology proved either the inner and outer retina is impacted by AMD and that these two impairments are associated. Therefore, the purpose of this review is to provide a description of the role of neurodegeneration in AMD in order to better understand the relationship between neuronal loss and the outer retinal damage in this disease.

Hyperreflective Foci Precede Macular Neovascularization Formation in Angioid Streaks.

To describe the steps leading to the development and progression of macular neovascularization (MNV) in angioid streaks (AS). The study was designed as retrospective, longitudinal case-series. AS patients were investigated by means of multimodal imaging, including fundus autofluorescence and structural optical coherence tomography (OCT). Main outcome measures were hyperreflective foci (HF) and MNV progression steps. Overall, 40 eyes (20 patients) affected by AS were evaluated. Over the follow-up, 5 eyes of 5 patients developed MNV. The mean follow-up was of 1.6 years. The mean number of anti-VEGF injections was 4.35±1.4. Mean BCVA was 0.53±0.38 LogMAR at the MNV onset, improving to 0.42±0.40 LogMAR at the end of the follow-up (p>0.05). Intraretinal HF onset and coalescence represented the first alterations occurring before the onset of the MNV. Anti-VEGF treatment was associated with exudation relapsing and remitting, with still present intraretinal hyperreflective foci and pigment accumulation. The longitudinal analysis of our cohort of eyes outlined the event timeline: 1.2 months to find concentrated HF, 4.5 months to observe pigment organization through the outer nuclear layer, and 1.5 years to detect MNV. HF formation, concentration and migration represent early alterations occurring before the onset of the MNV in AS.

Continuous Eplerenone Treatment in Chronic Central Serous Chorioretinopathy: Long-Term Results from a Pilot Study.

To assess the long-term morpho-functional retinal and choroidal changes in chronic central serous chorioretinopathy (cCSC) pachychoroid eyes in response to continuous oral eplerenone (EPL) treatment. This pilot study was conducted on patients with unilateral exudative cCSC. We enrolled a total of 17 exudative cCSC and 17 non-exudative fellow eyes of 17 patients. Baseline best-corrected visual acuity (BCVA) and anatomical (structural optical coherence tomography [OCT] and OCT angiography) parameters in both eyes were collected at baseline. Follow-up data were collected at 6, 12, and 48 months after initiation of EPL treatment. (i) Exudative cCSC eyes: Compared with baseline (0.34±0.13 LogMAR), BCVA significantly improved at follow-up examinations (6 months: 0.28±0.13 LogMAR, p=0.039; 12 months: 0.22±0.11 LogMAR, p=0.025; 48 months: 0.21±0.08 LogMAR, p=0.028). Furthermore, there was a significant reduction from baseline in all structural OCT parameters (subretinal fluid and subfoveal choroidal thickness [SFCT]; p<0.05). (ii) Non-exudative fellow eyes: There was no significant change in BCVA. There was a significant reduction from baseline in SFCT and choriocapillaris flow deficit percentage (p<0.05). In this pilot study, continuous oral EPL therapy in cCSC pachychoroid eyes resulted in long-term morpho-functional improvement. The beneficial effect of EPL occurred within the first year and was maintained after four years. Based on these preliminary observations, EPL may be effective in the exudative forms of CSC.

Foveal Eversion is Associated with High Persistence of Macular Edema and Visual Acuity Deterioration in Retinal Vein Occlusion.

Foveal eversion (FE) is a recently described optical coherence tomography (OCT) finding associated with negative outcome in diabetic macular edema. The main goal of the present study was to investigate the role of the FE metric in the diagnostic workup of retinal vein occlusion (RVO). This study was a retrospective, observational case series. We included 168 eyes (168 patients) affected by central RVO (CRVO) and 116 eyes (116 patients) affected by branch (RVO). We collected clinical and imaging data from CRVO and BRVO eyes affected by macular edema with a minimum follow-up of 12months. On structural OCT, we classified FE as pattern 1a, characterized by thick vertical intraretinal columns, pattern 1b, presenting thin vertical intraretinal lines, and pattern 2, showing no signs of vertical lines in the context of the cystoid macular edema. For statistical purposes, we considered data collected at baseline, after 1 year and at the last follow-up. The mean follow-up was 40 ± 25months for CRVO eyes and 36 ± 24months for BRVO eyes. We found FE in 64 of 168 CRVO eyes (38%) and in 25 of 116 BRVO eyes (22%). Most of the eyes developed FE during the follow-up. For CRVO eyes, we found 6 eyes (9%) with pattern 1a, 17 eyes (26%) with pattern 1b and 41 eyes (65%) with pattern 2. Of those BRVO eyes with FE, we found 8 eyes (32%) with pattern 1a + 1b and 17 eyes (68%) with pattern 2. In both CRVO and BRVO the presence of FE was significantly associated with higher persistence of macular edema and worse outcome, with FE pattern 2 representing the most severe condition. Remarkably, FE patterns 1a and 1b were characterized by BCVA stability over the follow-up, whereas FE pattern 2 showed significant bestcorrected visual acuity (BCVA) worsening at the end of the follow-up. FE can be considered a negative prognostic biomarker in RVO, associated with higher persistence of macular edema and worse visual outcome. Müller cell impairment might represent the pathogenic mechanism leading to the loss of macular structural support and impairment of fluid homeostasis.

The retinal neurovascular coupling is impaired in men with vasculogenic erectile dysfunction

The aim of this study was to study the retinal vessels in patients affected by vasculogenic erectile dysfunction (ED), using dynamic vessel analyzer (DVA). Patients with vasculogenic ED and control subjects were prospectively enrolled to undergo a complete urological and ophthalmologic evaluation, including DVA and structural optical coherence tomography (OCT). The main outcome measures were: (1) arterial dilation; (2) arterial constriction; (3) reaction amplitude (the difference between arterial dilation and constriction); and, (4) venous dilation. Thirty-five patients with ED and 30 male controls were included in the analysis. Mean ± SD age was 52.0 ± 10.8 years in the ED group and 48.1 ± 16.3 years in the control group (p = 0.317). In the dynamic analysis, the arterial dilation was lower in the ED group (1.88 ± 1.50%), as compared with the control group (3.70 ± 1.56%, p < 0.0001). Neither arterial constriction nor venous dilation differed between groups. The reaction amplitude was decreased in ED patients (2.40 ± 2.02%, p = 0.023), compared to controls (4.25 ± 2.20%). In the Pearson correlation analysis, the ED severity, was directly correlated with both reaction amplitude (R = .701, p = 0.004) and arterial dilation (R = .529, p = 0.042). In conclusion, subjects with vasculogenic ED are featured by a significant dysfunction of the retinal neurovascular coupling, which is inversely correlated with ED severity.

Structural and clinical changes in previously treated type 1 macular neovascularization in non-responder AMD eyes switched to brolucizumab.

To examine structural and clinical changes in previously treated type 1 macular neovascularization (MNV) in non-responder age-related macular degeneration (nAMD) eyes switched to brolucizumab. Subretinal hyper-reflective material (SHRM), intraretinal (IRF) and subretinal fluid (SRF) presence, fibrovascular-pigment epithelium detachment (PED) height and central macular thickness (CMT) variation were analyzed using optical coherence tomography (OCT). In this prospective study all patients underwent a complete ophthalmological evaluation including structural OCT at baseline (T0), one month (T1), three (T2), four (T3) and six months after switching to brolucizumab treatment (T4). Non-responder criterion was the persistence of IRF and SRF. Moreover, CMT and BCVA had shown worsening or no improvement before switching to brolucizumab. Clinical function and structural activity biomarkers were measured at each visit and changes were analyzed. P value <0.05 was considered statistically significant. Twenty eyes of twenty patients were enrolled. All the structural variables examined during the follow-up showed significant reductions. Decreases in IRF, SRF and PED were already significant at T1 (p < 0.05). SHRM was significantly reduced at T2 (p < 0.05). Structural biomarkers were absent at T3. At T4, all biomarkers remained stable while SHRM was no longer detectable in 18 patients. Changes in visual acuity from baseline to T4 were not significant. This short-term experience highlights that brolucizumab might be considered an effective treatment option in nAMD with type 1 MNV, as it can promote a reduction of structural activity biomarkers.

En-face optical coherence tomography hyperreflective foci of choriocapillaris in central serous chorioretinopathy

The purpose of this study is to evaluate choroidal hyperreflective foci (HRF) changes in central serous chorioretinopathy (CSC) on en-face optical coherence tomography (OCT). Retrospective analysis of 42 patients with unilateral CSC (84 eyes, including fellow eyes for controls) and 42 age- and sex-matched controls. With 4.5 × 4.5 mm macular scans, structural en-face OCT choriocapillaris (CC) slabs were used to calculate the density and number of HRF in acute CSC eyes with serous retinal detachment (SRD), resolved CSC eyes without SRD, unaffected fellow eyes, control eyes, and 1-year follow-up eyes. Based on the 2-disc diameter (3000 μm), the en-face OCT scan was divided into foveal and perifoveal lesion and analyzed to consider the impact of SRF in HRF measurement. Regression analyses were performed on the several factors with HRF number and density in the acute and resolved CSC eyes. The perifoveal density and number of CC HRF was significantly lower in the resolved CSC eyes when compared to the acute CSC eyes (P = 0.002, both), fellow eyes (P = 0.042/density, 0.028/number), and controls (P = 0.021/density, P = 0.003/number). There was no significant difference between the acute CSC eyes, fellow eyes, controls, and 1-year follow-up eyes. As subfoveal choroidal thickness decreased and choroidal vascularity (CVI) increased, the perifoveal density and number of HRF was measured higher with a significant correlation in univariate regression analysis of the acute and resolved CSC eyes (all, P < 0.05). The authors hypothesized that stromal edema induced by choroidal congestion and hyperpermeability has the greatest influence on HRF measurement, possibly affected by inflammatory cells and materials extravasation.

Quantification of linear and nonlinear elasticity by compression optical coherence elastography for determining lymph node status in breast cancer

We report the first application of compression optical coherence elastography (C-OCE) to evaluate both linear and nonlinear elastic properties of lymph nodes (LNs) for assessing their status, which is an important factor for detecting metastasis and staging breast cancer. The reported study involved 27 excised sentinel and axillary LNs from 24 patients with breast cancer, including normal LNs (n = 6), reactive LNs with follicular hyperplasia (n = 7) and sinus histiocytosis (n = 8), and metastatic LNs (n = 6). C-OCE data were compared with co-registered gold-standard histopathology and demonstrated a significantly higher contrast in differentiation of LNs as compared to structural optical coherence tomography imaging. Normal LNs are characterized by low stiffness values in the areas of LN cortex (<200 kPa). C-OCE revealed that abnormal reactive LNs with follicular hyperplasia exhibit moderately increased stiffness (200–300 kPa) in the cortex areas and more pronounced stiffness increase (400–600 kPa) in the areas of sinus histiocytosis. LNs with total metastasis exhibit fairly uniformly distributed highest stiffness values (>600 kPa). Since in terms of the tangent Young’s modulus there remained an appreciable overlap among these types of LNs, we also evaluated their elastic nonlinearity parameters. Complementary usage of both linear and nonlinear elastic parameters enabled very clear differentiation of all four main states of LNs. Thus, C-OCE imaging demonstrates high potential for future intraoperative usage to rapidly determine the LN status during breast-conserving surgery and to assess the extent of the cancer cells propagation in regional lymphatic collectors for preserving benign LNs. This is important for reducing the associated risks and complications (such as lymphedema) from excessive surgical removal of lymphoid structures.

Capturing the Transition From Intermediate to Neovascular AMD: Longitudinal Inner Retinal Thinning and Factors Associated With Neuronal Loss.

To estimate the impact of transition from intermediate to exudative neovascular age-related macular degeneration (AMD) on the inner retina and to assess the relationship of clinical characteristics and optical coherence tomography (OCT) findings with inner retinal changes. A total of 80 participants (80 eyes) with intermediate AMD at baseline who developed neovascular AMD within 3 months were included in the analysis. OCT scans at follow-up visits (after transition to neovascular AMD) were compared with values at the latest visit with evidence of intermediate AMD to quantify longitudinal inner retinal changes. OCT images were also reviewed for qualitative features reflecting distress of the outer retina or retinal pigment epithelium and for the presence and characteristics of exudation. The parafoveal and perifoveal inner retinal thicknesses were 97.6 ± 12.9 µm and 103.5 ± 16.2 µm, respectively, at baseline, and a significant increase in values was detected at the visit with first evidence of neovascular AMD (parafoveal: 99.0 ± 12.8 µm, P = 0.040; perifoveal: 107.9 ± 19.0 µm, P = 0.0007). Conversely, the inner retina was significantly thinner at the 12-month follow-up visit after initiation of the anti-vascular endothelial growth factor therapy (parafoveal: 90.3 ± 14.8 µm, P < 0.0001; perifoveal: 92.0 ± 21.3 µm, P < 0.0001). At the 12-month follow-up visit, OCT evidence of alterations of the external limiting membrane and history of previous intraretinal fluid were associated with a greater inner retinal thinning. The development of exudative neovascularization is associated with significant neuronal loss that may be detected once the exudation is resolved. OCT analysis demonstrated a significant relationship between morphological alterations detected using structural OCT and the amount of inner neuronal loss.

Ziv-aflibercept in Diabetic Macular Edema: Relation of Subfoveal Choroidal Thickness with Visual and Anatomical Outcomes.

To evaluate the effects of intravitreal ziv-aflibercept injections (IVZ) on subfoveal choroidal thickness (SCT) as well as on central macular thickness (CMT) and on best corrected visual acuity (BCVA) changes in eyes with center-involved diabetic macular edema (CI-DME). Fifty-seven eyes of 36 patients with CI-DME were included in this prospective interventional case series. Structural optical coherence tomography (OCT) and enhanced depth imaging OCT were performed at baseline followed by three monthly 1.25 mg IVZ injections. Changes of SCT, CMT, and BCVA at each follow-up session were assessed. The association between baseline SCT and its monthly changes with final visual and anatomical outcomes were also assessed. CMT at baseline, and at the first, second, and third month follow-up sessions were 396 119, 344 115, 305 89, and 296 101 μm, respectively (P-value 0.001). SCT at baseline, and at months one, two, and three were 236 47, 245 56, 254 54, and 241 54 μm, respectively (P-value 0.99). Corresponding figures for BCVA were 0.58 0.29, 0.47 0.31, 0.4 0.24, and 0.37 0.23 LogMAR, respectively (P-value 0.001). There was a statistically significant positive correlation between BCVA and CMT changes following IVZ injections (P-value 0.001). However, there were no significant correlations between SCT changes and visual acuity (VA) and CMT changes following IVZ injections. IVZ improved visual outcomes and macular thickness profiles in patients with CI-DME. However, IVZ had no significant effect on SCT. Baseline SCT and its monthly changes had no association with visual and anatomical outcomes.

Imaging Biomarkers of Mesopic and Dark-Adapted Macular Functions in Eyes With Treatment-Naïve Mild Diabetic Retinopathy

To investigate the relationship between imaging biomarkers and mesopic and dark-adapted (i.e. scotopic) functions in patients with firstly detected treatment-naïve mild diabetic retinopathy (DR) and normal visual acuity. Prospective cross-sectional study. In this study, 60 patients with treatment-naïve mild DR (ETDRS 20-35) and 30 healthy controls underwent microperimetry, structural optical coherence tomography (OCT) and OCT angiography (OCTA). The foveal mesopic (22.4±4.5 dB and 25.8±2.0 dB, p=0.005), parafoveal mesopic (23.2±3.8 and 25.8±1.9, p<0.0001), and parafoveal dark-adapted (21.1±2.8 dB and 23.2±1.9 dB, p=0.003) sensitivities were reduced in DR eyes. For the foveal mesopic sensitivity, the regression analysis showed a significant topographical association with choriocapillaris flow deficits percentage (CC FD%; β: -0.234, p=0.046) and ellipsoid zone (EZ) "normalized" reflectivity (β: 0.282, p=0.048). The parafoveal mesopic sensitivity was significantly topographically associated with inner retinal thickness (β: 0.253, p=0.035), deep capillary plexus (DCP) vessel length density (VLD; β: 0.542, p=0.016), CC FD% (β: -0.312, p=0.032), and EZ "normalized" reflectivity (β: 0.328, p=0.031). Similarly, the parafoveal dark-adapted sensitivity was topographically associated with inner retinal thickness (β: 0.453, p=0.021), DCP VLD (β: 0.370, p=0.030), CC FD% (β: -0.282, p=0.048), and EZ "normalized" reflectivity (β: 0.295, p=0.042). In treatment-naïve mild DR eyes, both rod and cone functions are affected and they are associated with both DCP and CC flow impairment, which suggests that a macular hypoperfusion at these levels might implicate a reduction in photoreceptor function. The "normalized" EZ reflectivity may be a valuable structural biomarker for assessing the photoreceptor function in DR.

Nondestructive label-free detection of peritumoral white matter damage using cross-polarization optical coherence tomography

To improve the quality of brain tumor resections, it is important to differentiate zones with myelinated fibers destruction from tumor tissue and normal white matter. Optical coherence tomography (OCT) is a promising tool for brain tissue visualization and in the present study, we demonstrate the ability of cross-polarization (CP) OCT to detect damaged white matter and differentiate it from normal and tumor tissues. The study was performed on 215 samples of brain tissue obtained from 57 patients with brain tumors. The analysis of the obtained OCT data included three stages: 1) visual analysis of structural OCT images; 2) quantitative assessment based on attenuation coefficients estimation in co- and cross-polarizations; 3) building of color-coded maps with subsequent visual analysis. The defining characteristics of structural CP OCT images and color-coded maps were determined for each studied tissue type, and then two classification tests were passed by 8 blinded respondents after a training. Visual assessment of structural CP OCT images allows detecting white matter areas with damaged myelinated fibers and differentiate them from normal white matter and tumor tissue. Attenuation coefficients also allow distinguishing all studied brain tissue types, while it was found that damage to myelinated fibers leads to a statistically significant decrease in the values of attenuation coefficients compared to normal white matter. Nevertheless, the use of color-coded optical maps looks more promising as it combines the objectivity of optical coefficient and clarity of the visual assessment, which leads to the increase of the diagnostic accuracy of the method compared to visual analysis of structural OCT images. Alteration of myelinated fibers causes changes in the scattering properties of the white matter, which gets reflected in the nature of the received CP OCT signal. Visual assessment of structural CP OCT images and color-coded maps allows differentiating studied tissue types from each other, while usage of color-coded maps demonstrates higher diagnostic accuracy values in comparison with structural images (F-score = 0.85-0.86 and 0.81, respectively). Thus, the results of the study confirm the potential of using OCT as a neuronavigation tool during resections of brain tumors.

Optical Coherence Tomography Angiographic Evaluation of Macular Vessel Density in Diabetic Macular Edema After Intravitreal Dexamethasone Implants: A Prospective Interventional Trial.

The goal of this study was to assess macular vascular density evolution, macular thickness, and functional outcomes after intravitreal dexamethasone implants for diabetic macular edema. Vascular density was evaluated with optical coherence tomography (OCT) angiography in 21 eyes. Macular thickness was evaluated with structural OCT. Visual acuity and contrast sensitivity were evaluated before and after treatment, and these functional outcomes were analyzed for association with anatomic outcomes. Macular vessel density in the superficial capillary plexus was evaluated with OCT angiography and quantified in areas with no fluid, allowing a more accurate measurement and eliminating the segmentation bias in areas with intra-retinal fluid. Such a methodology was possible by positioning the scans only in areas with no fluid before and after the implant. The absence of fluid in these areas was confirmed by three experienced evaluators using both the B-scan and the en face. Visual acuity and contrast sensitivity were evaluated before and after treatment, and these functional outcomes were analyzed for association with anatomic outcomes. At 30, 60, and 90 days after implantation, there was improvement in macular perfusion in areas without fluid after intravitreal dexamethasone implantation, accompanied by reduced macular thickness and improved visual acuity (P < .001). However, there was no improvement in contrast sensitivity after treatment. Improved macular perfusion after treatment with intravitreal dexamethasone implantation may be associated with modulation of leukostasis, when the release of cytokines leads to capillary endothelial damage and obstruction of the micro-vasculature, leading to impaired capillary perfusion and ischemic damage. Despite the anatomical and functional findings demonstrated, further studies are needed to prove the relationship between the inflammatory mechanisms of diabetic macular edema and its relationship with macular perfusion and functional aspects. [Ophthalmic Surg Lasers Imaging Retina 2023;54(3):174-182.].

Quantification of elastic anisotropy of human skin in vivo with dynamic optical coherence elastography and polarization-sensitive OCT

The complex structure of skin ensures a broad range of biological functions. The loss of a large skin area due to trauma or disease usually requires reconstructive surgery that often involves grafting or flapping. The clinical need for non-contact objective measurements of skin elasticity is necessary to guide grafting procedures to minimize complications such as secondary contracture or hypertrophic scars. Here, we report a non-contact and non-invasive method combining acoustic micro-tapping optical coherence elastography (AμT-OCE) with polarization-sensitive (PS-) optical coherence tomography (OCT) to quantify anisotropic elastic properties of skin. We show that all three elastic constants that define skin’s anisotropic elastic deformation and the orientation of collagen fibers in the dermis can be determined from propagating elastic waves over the skin surface. Measurements were performed on healthy volunteers in vivo. A nearly incompressible transverse isotropic model of skin elasticity was used to reconstruct the moduli from experimental data after being validated in extensive numerical simulations. Finally, we demonstrate that combining several OCT modalities (structural OCT, OCT angiography, PS-OCT, and AμT-OCE) may provide rich information about skin and demonstrate the potential for complex characterization of scar.

Optical Coherence Tomography Angiography Demonstrates Strain and Volume Effects on Optic Disk and Peripapillary Vasculature Caused by Horizontal Duction

Purpose The optic nerve mechanically loads the eye during ocular rotation, thus altering the configuration of the disk and peripapillary tissues. We used optical coherence tomography (OCT) angiography (OCTA) to investigate mechanical strains and volume changes in disk and peripapillary blood vessels during horizontal duction. Methods Structural OCT and OCTA were performed centered on optic disks; imaging was repeated in central gaze, and in 30° ab- and adduction. By an algorithm employing point-set registration of 3 D features, we developed a novel approach for measuring disk strains, and strains and volumes of the blood vessels associated with horizontal duction. Repeatability was demonstrated in each gaze position. Results 19 eyes of 10 healthy adults of average age 37 ± 15 (standard deviation, SD) years were imaged. The method was validated by demonstrating numerically consistent vascular volumes and strains for repeated imaging under identical conditions. Compared with central gaze, vascular volume increased by 5.2 ± 4.1% in adduction. Adduction and abduction caused strains of 3.0 ± 1.6% and 2.6 ± 1.8% in the optic disk, whereas blood vessels showed greater strains of 8.1 ± 1.3% and 8.2 ± 1.7%. Decomposition of strain components depending on directionality and regions demonstrated that adduction induces significant net tensile strains, suggesting traction exerted by the optic nerve. The decomposition also showed that nasotemporal compressive strains are larger in temporal hemidisks than nasal hemidisks. The Bruch’s membrane opening was significantly compressed horizontally in adduction by 1.1% (p = .009). Conclusion This novel analysis combining structural OCT and OCTA demonstrates that optic disk compression during adduction is associated with disk and vascular strains much larger than reported for intraocular pressure elevation and pulsatile perfusion, as well as compressing the disk and increasing peripapillary vascular volume. These changes may be relevant to the pathogenesis of optic nerve and retinal vascular disorders.

Analysis of the pachychoroid phenotype in an Asian population: methodology and baseline study population characteristics

AimTo describe the clinical characteristics in a cohort of patients with the pachychoroid phenotype and to evaluate the association of ocular and systemic factors with type of complications observed.MethodsWe report...

Automated large-scale prediction of exudative AMD progression using machine-read OCT biomarkers.

Age-related Macular Degeneration (AMD) is a major cause of irreversible vision loss in individuals over 55 years old in the United States. One of the late-stage manifestations of AMD, and a major cause of vision loss, is the development of exudative macular neovascularization (MNV). Optical Coherence Tomography (OCT) is the gold standard to identify fluid at different levels within the retina. The presence of fluid is considered the hallmark to define the presence of disease activity. Anti-vascular growth factor (anti-VEGF) injections can be used to treat exudative MNV. However, given the limitations of anti-VEGF treatment, as burdensome need for frequent visits and repeated injections to sustain efficacy, limited durability of the treatment, poor or no response, there is a great interest in detecting early biomarkers associated with a higher risk for AMD progression to exudative forms in order to optimize the design of early intervention clinical trials. The annotation of structural biomarkers on optical coherence tomography (OCT) B-scans is a laborious, complex and time-consuming process, and discrepancies between human graders can introduce variability into this assessment. To address this issue, a deep-learning model (SLIVER-net) was proposed, which could identify AMD biomarkers on structural OCT volumes with high precision and without human supervision. However, the validation was performed on a small dataset, and the true predictive power of these detected biomarkers in the context of a large cohort has not been evaluated. In this retrospective cohort study, we perform the largest-scale validation of these biomarkers to date. We also assess how these features combined with other EHR data (demographics, comorbidities, etc) affect and/or improve the prediction performance relative to known factors. Our hypothesis is that these biomarkers can be identified by a machine learning algorithm without human supervision, in a way that they preserve their predictive nature. The way we test this hypothesis is by building several machine learning models utilizing these machine-read biomarkers and assessing their added predictive power. We found that not only can we show that the machine-read OCT B-scan biomarkers are predictive of AMD progression, we also observe that our proposed combined OCT and EHR data-based algorithm outperforms the state-of-the-art solution in clinically relevant metrics and provides actionable information which has the potential to improve patient care. In addition, it provides a framework for automated large-scale processing of OCT volumes, making it possible to analyze vast archives without human supervision.