En-face Optical Coherence Tomography Research Articles

Retinal arteriolar calcification and ischemic retinopathy in a patient with chronic kidney disease

A 58-year-female with a history of chronic kidney disease presented with defective vision in both the eyes (BE). Her vision was 20/120 in the right eye (RE) and 20/200 in the left eye (LE). Fundus evaluation revealed retinal arteriolar calcification, neovascularization of the disc (NVD), and drusen at the posterior pole in BE. Optical coherence tomography (OCT) images passing through the retinal arterioles indicated hyper reflective structures with back shadowing suggestive of intravascular calcification. En-face OCT angiography images over the optic discs were suggestive of NVD in BE. Blood investigation revealed elevated levels of phosphate and the product of calcium and phosphate levels. The patient was treated with pan-retinal photocoagulation in BE. However, the visual outcome was poor.

Recurrent Episodes with Serous Retinal Detachment and Anterior Uveitis in a Patient Using Nivolumab (Anti -PD-1 Antibody) Therapy: A case report and literature review

ABSTRACT Aim: Nivolumab is an immune checkpoint inhibitor that has recently been widely used for metastatic malignant melanoma. We report a case who developed multiple different ocular immune-related side effects (iRAEs) related to nivolumab. Case Presentation: A 60-year-old man on nivolumab treatment for metastatic malignant melanoma developed a decrease in vision in both eyes several days after the third infusion. The initial best-corrected visual acuity (BCVA) was counting fingers in both eyes. Slit-lamp examination revealed no abnormal findings in the anterior segment of both eyes. Posterior segment evaluation showed serous retinal detachment, including the whole macula and inferior retina in both eyes, and optical coherence tomography (OCT) confirmed the diagnosis. On en face OCT analysis, hyperautoflorescent dots were noticed on the whole macular region but more intense at the inferior quadrant corresponding to serous retinal detachment. On Fluorescein Angiography (FA), no abnormality was observed. Oral corticosteroid treatment was administered. Subretinal fluid resolved one week after treatment in the right eye and two weeks after treatment in the left eye. BCVA was 20/20 in both eyes at first month of treatment. After that, oral corticosteroid treatment was tapered and stopped at the end of the second month. The patient was followed monthly. Two months after the treatment patient presented with an anterior uveitis episode with mild vision loss. Slit-lamp examination revealed 3+ cells in the anterior chamber and posterior synechia in both eyes. Posterior segment examination was normal. The patient was treated with topical corticosteroid and cycloplegic for two months. Hyperautoflorescent dots formed with serous detachment disappeared six months after the onset of serous detachment, and they did not occur during anterior uveitis episodes. Conclusions: This is the first clinical report of nivolumab-associated ocular iRAEs presenting with recurrent episodes presenting with serous retinal detachment and anterior uveitis. En face OCT imaging may help diagnose and show the activity of the posterior segment manifestation. When managed properly and observed closely following general and ocular conditions, it is possible to held iRAEs and overcome them by oral and/or topical corticosteroid therapy without interrupting the nivolumab.

Multimodal Imaging of Lamellar Macular Holes.

Evolution of imaging techniques has renewed interest in the diagnosis of lamellar macular hole (LMH) and greatly implemented the possibilities of gaining more detailed insights into its pathogenesis. Among noninvasive techniques, optical coherence tomography (OCT) is considered the primary examination modality to study LMHs, given its ability to image foveal structure and its widespread availability. OCT also allows to resolve the epiretinal materials associated with LMH, i.e., tractional epiretinal membranes (ERMs) and epiretinal proliferation (EP). En face OCT reconstructions are useful to confirm the foveal abnormalities shown by the eyes with LMH, whereas OCT angiography may reveal alterations of the size and shape of the foveal avascular zone and alterations of the density of the superficial and deep vascular plexuses. On slit-lamp biomicroscopy or fundus camera examination, LMH appears as a round or oval, reddish lesion at the center of the macula, slightly darker than the surrounding retina. The associated tractional ERM, causing wrinkling and glistening of the retinal surface, is usually readily appreciable, whereas EP is hardly apparent on biomicroscopy or fundus photography since the retina surface appears smooth. When imaged with blue fundus autofluorescence (B-FAF) imaging, LMHs are characterized by an increased autofluorescent signal, the intensity of which does not correlate with the thickness of the residual outer retinal tissue. Green reflectance and blue reflectance (BR) images clearly show the increased reflection and wrinkling of the retinal surface caused by tractional ERM associated with LMH. BR and multicolor imaging enable the visualization of EP associated with LMH in the form of a sharply demarcated dark area and in the form of a yellowish area surrounding the hole, respectively. Scarce data regarding invasive imaging techniques, such as fluorescein angiography, for the study of LMH are available in the literature. The aim of this review is to evaluate the contribution that each imaging modality can provide to study the morphologic characteristics of LMH.

Quantification of Early and Intermediate Age-related Macular Degeneration Using OCT "en face" Presentation.

Early and intermediate age-related macular degeneration (AMD) results in drusen deposits under the retinal pigment epithelium (RPE). These early stages of AMD exhibit different risks of progressing to late AMD. To date, early AMD has been classified and quantified by fundus photography. This does not appear to be sensitive enough for clinical trials studying the impact on drusen. SD-OCT with two-dimensional rendering of the segmented slices analysed allows for en face imaging of the drusen. The present trial studied the potential of quantifying early and intermediate AMD by en-face optical coherence tomography (OCT). Thirty-one eyes of 29 patients in different stages of early and intermediate AMD were studied. To this end, fundus photographs (Kowa VX-10i, Kowa, Tokyo, Japan) and en-face OCT images (RTVue XR Avanti, Optovue, Inc., Fremont, CA, USA) were taken. First, different segmentation levels (6 µm underneath the RPE, on the RPE, 6 µm and 9 µm above the RPE) and different layer thicknesses (5 µm, 10 µm, 20 µm and 30 µm) were analysed to determine the best segmentation for visualising drusen. Drusen were marked manually and their number and surface area calculated. This analysis was then compared with the standardised drusen analyses on fundus photography. Additional changes in early and intermediate AMD such as pigment epithelial detachments (PEDs) and subretinal drusenoid deposits (SDD) as well as small atrophies were also documented and compared. The best segmentation for delineating the drusen on the en-face OCT images was found to be a segmentation 6 µm underneath the RPE with a slice thickness of 20 µm. Comparison of drusen quantification on en-face OCT images with the standardised drusen analysis on fundus photography revealed particularly good similarity. Other changes in early and intermediate AMD, such as PEDs, SDD and small atrophies, were easier to assess on the en-face OCT images. The analysis and quantification of drusen from en-face OCT images with 20 µm segmentation at 6 µm underneath the RPE allows differentiated quantification of various drusen characteristics. Moreover, other changes in early and intermediate AMD can also be analysed. In future observational and clinical trials, this could help quantify drusen.

Outer nuclear layer relevance in visual function correlated to quantitative enface OCT parameters in Stargardt disease.

To evaluate the correlation between Best Corrected Visual Acuity (BCVA) and the following parameters in Stargardt Disease (STGD): Central Retinal Thickness (CR-T), Central Outer Nuclear Layer Thickness (C-ONL-T), Areas of macular Photoreceptor loss (PHRa), and Retinal Pigment Epithelium (RPE) loss (RPEa). A total of 64 eyes of 32 STGD patients were included in the study. All patients received a comprehensive ophthalmological examination, color fundus photographs, fundus auto-fluorescence imaging, and Optical Coherence Tomography (OCT). The CR-T and C-ONL-T were evaluated from standard SD-OCT scans. The PHRa and RPEa were calculated from enface OCT scans (sub RPE slab and photoreceptor slab). The collected OCT parameters were evaluated for possible association with BCVA. The mean macular PHRa and RPEa was 16.16 ± 13.36 and 12.05 ± 12.57 mm2 respectively. The mean CR-T measured 120.78 ± 41.49 μm while the mean C-ONL-T was assessed at 4.60 ± 13.73 μm. BCVA showed the highest correlation with the C-ONL-T (r = -0.72; p < 0.001) while there was no correlation with the CR-T (r = -0.17; p = 1.00). Enface OCT permits a rapid and precise quantitative evaluation of the macular PHR and RPE atrophy area in STGD. Nonetheless, the OCT parameter that showed the highest correlation with visual acuity in STGD was the ONL thickness.

The sensitivity and specificity of retinal and choroidal folds to distinguish between mild papilloedema and pseudopapilledema.

To determine if the presence or absence of retinal and choroidal folds on SD-OCT imaging can distinguish between mild papilloedema and pseudopapilledema. Cross-sectional cohort study METHODS: Subjects with optic disc elevation (Frisen grades 1 and 2 only) were eligible to be enrolled prospectively. Pseudopapilledema was defined as a lack of change in optic disc appearance between two visits <6 months apart, and papilloedema was defined as change in optic disc appearance between two visits <6 months apart determined by review of fundus photographs by a masked neuro-ophthalmologist. Three masked neuro-ophthalmologists independently reviewed en face and axial optical coherence tomography (OCT) images of the optic nerve of the study subjects for the presence or absence of retinal and choroidal folds. Concordance was determined when there was agreement between at least 2 of the 3 observers. Forty-five subjects (78 eyes) met inclusion criteria. There were 32 eyes with papilloedema and 46 eyes with pseudopapilledema. Choroidal and/or retinal folds were detected in 38% of eyes (12/32) with papilloedema and 19.6% of eyes (9/46) with pseudopapilledema. Post-hoc analyses eliminated six questionable cases of pseudopapilledema that had ancillary testing suggestive of elevated intracranial pressure and resulted in one remaining eye (2%) with more certain pseudopapilledema that was found to have folds. En face OCT imaging was more sensitive (71%) in detection of folds than axial OCT imaging (57%). Choroidal and/or retinal folds on OCT are commonly observed in patients with mild papilloedema and are uncommon in those with pseudopapilledema. The presence of folds on OCT in patients presenting with disc elevation suggests papilloedema.

Analysis of the impact of optical aberrations in en-face full-field OCT microscopy.

Optical coherence tomography (OCT) is a powerful technique for cross-sectioning imaging. However, the lateral resolution may be degraded by optical aberrations originating from the sample or the setup. We present an extensive quantitative study of the impact of aberrations in time-domain en-face full-field OCT (FFOCT). Using an adaptive optics loop integrated in an FFOCT setup, a deformable mirror is used to introduce low-order calibrated aberrations. The experimental analysis of both the line spread functions (SF) and the complex object images has allowed us to measure the loss in contrast and the impact on lateral spatial resolution. We demonstrate that the frequency content of FFOCT image spectra in terms of signal-to-noise ratio and cutoff frequency is degraded by aberrations but remains much higher than in conventional incoherent images. Line SF profiles in conventional imaging display widening, whereas in FFOCT they display oscillations, leading to the possible perception of preserved resolution. Nevertheless, for complex objects, the aberration image blurring is strong due to the convolution process by the point SF, resulting in a significant filtering of the image spatial spectrum.

Long-term capillary changes in areas of dissociated optic nerve fibre layer after macular hole surgery.

Internal limiting membrane (ILM) peeling for macular hole (MH) surgery may cause retinal abnormalities, visible on blue-filter fundus photographs as arcuate, slightly dark, extramacular striae along the course of retinal nerve fibres. This feature, showing a dissociated optic nerve fibre layer (DONFL) appearance, perfectly corresponds to focal dehiscences (‘dimplings’) in the retinal nerve fibre layer (RNFL) on B-scan optical coherence tomography (OCT) and to concentric macular dark spots on en-face scan OCT. Although such retinal changes seem not to preclude a good visual outcome, their origin is still unclear (Tadayoni et al. 2001). We report herein the long-term capillary changes occurring in DONFL areas in 38 MH patients (16 men, 22 women) treated with ILM peeling technique. All subjects underwent extensive ophthalmic examination and retinal imaging, including structural OCT, OCT angiography and colour-coded perfusion maps, before and after surgery. En-face OCT angiograms of the superficial capillary plexus (SCP) were evaluated and compared with structural OCT findings. All angiograms and OCT images were exported into a validated custom measurement software (ImageJ software version 1.50, National Institutes of Health, Bethesda, MD). En-face scan OCT of SCP slabs was binarized by Otsu’s method. DONFL location was automatically delineated, and DONFL edges were semi-automatically overlapped on the corresponding colour-coded perfusion maps. Finally, vascular perfusion density (VPD) values of each retinal sector were correlated with the corresponding DONFL area. All eyes were followed-up postoperatively for a mean of 25.2 ± 3.2 months (range 24–29 months). Anatomical MH closure was achieved in 37/38 (97.4%) eyes. At the last follow-up examination, 34/38 (89.5%) eyes had DONFL areas, mainly in the temporal macula. Overlapping of delineated DONFL areas with colour-coded perfusion maps showed a perfect correspondence between temporal DONFL areas and no-flow regions in the temporal SCP, whereas no such correspondence was found in other SCP sectors (Table 1). Macular changes following ILM peeling are still poorly understood. Muller cell (MC) footplates are in direct contact with RNFL bundles and contribute to ILM formation. The mechanical trauma secondary to ILM peeling is likely to cause an injury to these structures, resulting in axon swelling and gaps in the RNFL, which appear as DONFL areas. Furthermore, petechial haemorrhages, often occurring on the retinal surface during ILM peeling, could be the result of direct injury to SCP vessels. DONFL areas usually appear 1–3 months after surgery in the temporal macula, where MC footplates are more numerous, progressively increase in the following 3–6 months and completely surround the fovea within 12 months (Alkabes et al. 2011; Navajas et al. 2020). Thereafter, progressive regeneration of MC footplates and DONFL attenuation may occur (Nakamura et al. 2003; Kishimoto et al. 2011). In our study, DONFL areas were still detectable in the temporal sectors after two years, thus suggesting that macular restoration may have started nasally. Furthermore, we found a statistically significant correlation between the total area of DONFL and VPD values only in the temporal SCP. Overall, these findings support the idea that retinal reparation begins with SCP regeneration and is later followed by MC footplates restoration, with final attenuation and disappearance of DONFL. Accordingly, we hypothesize three steps in the process of retinal reparation after MH surgery: (1) development of roundish no-flow regions on colour-coded perfusion maps and DONFL areas on en-face scan OCT in the temporal SCP, where both vessels and MC have been damaged; (2) persistence of DONFL areas corresponding to normal perfusion regions (superior-middle, superior-nasal, inferior-middle and inferior-nasal sectors of the SCP), because vessel restoration has been completed, but MC is still damaged; and (3) injury to SCP vessels and MC has been completely restored and neither DONFL areas nor no-flow regions can be found (intermediate-nasal sector). Further larger prospective studies are warranted to confirm this theory and fully understand the pathogenesis underlying macular changes secondary to ILM peeling in MH patients.

Choroidal macrovessels: multimodal imaging findings and review of the literature

Background/aimsTo describe clinical and multimodal imaging features in a cohort of choroidal macrovessels.MethodsDemographics and multimodal imaging features of 16 eyes of 13 patients with choroidal macrovessels were reviewed. The multimodal...

Does size of telangiectasia on optical coherence tomography angiography influence vision in eyes with type 2 macular telangiectasia?

Purpose:To study the influence of dimensions of macular telangiectasia (MacTel) on enface optical coherence tomography angiography (OCTA) on vision and clinical parameters in eyes with MacTel type 2.Methods:MacTel was classified based on OCTA location, i.e. either temporal to the fovea (grade 1), or spread nasally (grade 2), or circumferentially (grade 3), or the presence of neovascular-like tissue in the outer retina–choriocapillary complex (ORCC) (grade 4). On enface images, the maximum dimensions of the MacTel in the deep plexus were noted using calipers by a single experienced observer.Results:Ninety-eight eyes of 49 patients with MacTel with a mean visual acuity was 0.46 + 0.26 logMAR and mean macular thickness of 202 ± 132 μ were included. Based on OCTA, grade 3 MacTel (n = 35, 36%) was the commonest followed by grade 4 (n = 28, 29%). The mean maximum vertical diameter of the MacTel was 2019 + 753 μ, and every 500 microns increment in vertical diameter of the MacTel was associated with a half-line drop in vision (95%CI = 0.005 to 0.08 logMAR, P = 0.03). Vision gradually reduced with increment in OCTA grades of MacTel from grade 1 to 3; however, the trend was not maintained in grade 4 MacTel, which showed better vision and lesser degenerative cysts.Conclusion:Larger telangiectasias were associated with significantly lower vision in MacTel. Eyes with deeper telangiectasia involving ORCC have better vision and evidence of far lesser neurodegeneration than type 3 disease, suggesting that this may not be part of the continuum and does not represent neovascularization.

Choroidal vessel density in unilateral hyperopic amblyopia using en-face optical coherence tomography

BackgroundStructural changes of the choroid, such as choroidal thickening, have been indicated in amblyopic eyes with hyperopic anisometropia as compared to fellow or healthy eyes. The purpose of the present study was to investigate choroidal vascular density (CVD) in children with unilateral hyperopic amblyopia.MethodsThis study included 88 eyes of 44 patients with unilateral amblyopia due to hyperopic anisometropia with or without strabismus and 29 eyes of 29 age-matched normal controls. The CVD of Haller’s layer was quantified from en-face images constructed by 3-dimensional swept-source optical coherence tomography images flattened relative to Bruch’s membrane. The analysis area was a 3 × 3-mm square of macula after magnification correction. Relationships between CVD and other parameters [best-corrected visual acuity (BCVA), refractive error and subfoveal choroidal thickness (SFCT)] were investigated, and CVDs were compared between amblyopic, fellow, and normal control eyes.ResultsMean CVD was 59.11 ± 0.66% in amblyopic eyes, 59.23 ± 0.81% in fellow eyes, and 59.29 ± 0.74% in normal control eyes. CVD showed a significant positive relationship with SFCT (p = 0.004), but no relationships with other parameters. No significant differences in CVD were evident among amblyopic, fellow, and normal control eyes after adjusting for SFCT (p = 0.502).ConclusionsCVD was unrelated to BCVA, and CVD did not differ significantly among amblyopic, fellow and normal control eyes. These results suggest that the local CVD of Haller’s layer is unaffected in unilateral hyperopic amblyopic eyes.

Characteristics of secondary epiretinal membrane due to peripheral break

This study aimed to investigate morphological differences between idiopathic epiretinal membrane (ERM) and secondary ERM due to peripheral break (SEPB) and to identify clinical characteristics in eyes with SEPB to facilitate peripheral retinal examination. The retrospective cross-sectional study involved 93 consecutive eyes in 91 patients who underwent ERM removal surgery. Eyes were divided into two groups: the macular pucker group and the idiopathic ERM group. En-face Optical Coherence Tomography (OCT) images, fundus photographs, severity of metamorphopsia (M-score) and clinical characteristics of each group were compared. ERM extent and eccentricity (ratio of the shortest and longest distances from the foveal center to the boundary) were obtained through en-face OCT imaging. Fundus photographs were used to judge whether the membrane was turbid or not. Patients with SEPB were younger than patients with idiopathic ERM (61.3 ± 7.5 vs. 66.6 ± 8.3 years; p < 0.05). Preoperative M-score and myopic refractive error, axial length were also significantly higher in the macular pucker group than in the idiopathic ERM group (all p < 0.05). There was no difference in ERM extent between the two groups. The incidence of ERM eccentricity was 23 of the 34 eyes (67.6%) in the SEPB group and 26 of the 59 eyes (44.1%) in the idiopathic ERM group (p < 0.05). The incidence of turbid ERM was 18 of the 34 eyes (52.9%) in the SEPB group and 10 of the 59 eyes (16.9%) in the idiopathic ERM group (p < 0.01). The SEPB group, compared with the idiopathic ERM group, tended to have eccentric, turbid ERM at a younger age and with more severe metamorphopsia and myopic refractive error.

Depth-resolved variations in visibility of retinal nerve fibre bundles across the retina in enface OCT images of healthy eyes.

Recent developments in optical coherence tomography (OCT) technology enable direct enface visualisation of retinal nerve fibre bundle (RNFB) loss in glaucoma. However, the optimum depth at which to visualise RNFBs across the retina is unknown. We aimed to evaluate the range of depths and optimum depth at which RNFBs can be visualised across the retina in healthy eyes. The central±25° retina of 10 healthy eyes from 10 people aged 57-75years (median 68.5years) were imaged with spectral domain OCT. Slab images of maximum axial resolution (4μm) containing depth-resolved attenuation coefficients were extracted from 0 to 193.5μm below the inner limiting membrane (ILM). Bundle visibility within 10 regions of a superimposed grid was assessed subjectively by trained optometrists (n=8), according to written instructions. Anterior and posterior limits of RNFB visibility and depth of best visibility were identified for each grid sector. Effects of retinal location and individual eye on RNFB visibility were explored using linear mixed modelling with likelihood ratio tests. Intraclass correlation coefficient (ICC) was used to measure overall agreement and repeatability of grading. Spearman's correlation was used to measure correlation between depth range of visible RNFBs and retinal nerve fibre layer thickness (RNFLT). Retinal location and individual eye affected anterior limit of visibility (χ2(9) =58.6 and 60.5, both p<0.0001), but none of the differences exceeded instrument resolution, making anterior limit consistent across the retina and different eyes. Greater differences were observed in the posterior limit of visibility across retinal areas (χ2(9) =1671.1, p<0.0001) and different eyes (χ2(9) =88.7, p<0.0001). Optimal depth for visualisation of RNFBs was around 20µm below the ILM in most regions. It varied slightly with retinal location (χ2(9) =58.8, p<0.0001), but it was not affected by individual eye (χ2(9) =10.7, p=0.29). RNFB visibility showed good agreement between graders (ICC 0.89, 95%CI 0.87-0.91), and excellent repeatability (ICC 0.96-0.99). Depth range of visible RNFBs was highly correlated with RNFLT (ρ=0.9, 95%CI: 0.86-0.95). The range of depths with visible RNFBs varies markedly across the healthy retina, consistently with RNFLT. To extract all RNFB information consistently across the retina, slab properties should account for differences across retinal locations and between individual eyes.

Multimodal Imaging for the Assessment of Geographic Atrophy in Patients with “Foveal” and “No-Foveal” Sparing

Introduction: The aim of the study was to evaluate the applicability of optical coherence tomography (OCT) angiography (OCTA) for measuring geographic atrophy (GA) areas in age-related macular degeneration (AMD) patients with “foveal” and “no-foveal” sparing disease and compare it to other imaging modalities. Methods: A multimodal imaging protocol was applied, using infrared (IR) imaging, fundus autofluorescence (FAF), OCTA, and en-face OCT in 35 eyes of 23 AMD patients with GA. Patients were classified into 2 groups, with and without foveal sparing disease. GA area measurements for all imaging modalities were compared for each group separately. Results: The measured GA area was estimated to be 6.68 ± 3.18 mm² using IR; 6.99 ± 3.09 mm² using FAF; 6.56 ± 3.11 mm² using OCTA, and 6.65 ± 3.14 mm² using en-face OCT. There was no statistically significant difference in the GA area between different modalities (p = 0.977). When separate analysis was conducted for patients with “foveal” and “no-foveal” sparing disease, although GA measurements in FAF imaging displayed higher numerical values than the other modalities, especially in patients with foveal sparing, no statistically significant difference in the GA area was found between the different imaging modalities in either group (p = 0.816 for foveal sparing; p = 0.992 for no-foveal sparing group). Conclusions: OCTA can be reliably used in the assessment of GA in AMD patients with and without foveal sparing disease. For both groups, measurements are comparable to IR, en-face OCT, and FAF, despite the fact that the latter recorded larger area of GA, mainly in the foveal sparing cases.

Choriocapillaris Flow Deficits and Treatment-Naïve Macular Neovascularization Secondary to Age-Related Macular Degeneration.

PurposeTo evaluate choriocapillaris (CC) flow deficits (FD) in eyes with treatment-naïve macular neovascularization (MNV) and to compare CC FD around exudative versus nonexudative MNV.MethodsTreatment-naïve eyes with a diagnosis of either exudative or nonexudative AMD and type 1 MNV were included. Normal control eyes were age-matched to each AMD eye one to one. En face optical coherence tomography angiograms were analyzed for percentage of CC FD (FD%) in two concentric 500 µm rings, ring 1 and ring 2, surrounding the dark halo around MNV. The mean CC FD% in ring 1 and ring 2 was evaluated for each eye. A secondary analysis was similarly carried out to investigate the differences in CC FD% in exudative versus nonexudative treatment-naïve MNV.ResultsTwenty-three eyes with treatment-naïve MNV were age matched with 23 normal controls. The mean CC FD% was significantly greater in both rings in the MNV versus the normal control group (P < 0.05) and was significantly greater in the inner ring, closer to the lesion, than the outer ring. The mean FD% was also greater in both rings in the exudative versus the nonexudative MNV group, but this difference did not reach statistical significance.ConclusionsThe CC FD% was greater in the area surrounding MNV versus age-matched normal controls and in the ring closer to the MNV lesion. Further, CC FD was greater in eyes with exudative versus nonexudative MNV in both rings surrounding the associated dark halo, although this difference was not statistically significant.

Multimodal Imaging Features and Clinical Relevance of Subretinal Lipid Globules

To describe the presence of subretinal lipid globules (SLG), analyze the multimodal imaging features inherent in their optical properties, and provide a means to distinguish them from other retinal structures and clinical signs. Retrospective cohort study. The clinical data and multimodal imaging features of 39 patients (49 eyes) showing SLG were evaluated. Patients underwent color fundus photography, near-infrared reflectance (NIR), spectral-domain (SD) and swept-source (SS) optical coherence tomography (OCT) and OCT angiography. Invitro phantom models were used to model OCT optical properties of water, mineral oil, and intralipid droplets and to investigate the optical mechanisms producing hypertransmission tails beneath SLG. The SLG were not visible in color fundus photographs or in NIR images. With both SD- and SS-OCT B-scans, SLG appeared as 31-157μm, round, hyporeflective structures demonstrating a characteristic hypertransmission tail previously described with lipid globules found in the choroid and in neovascular membranes. Similarly, with en face OCT, SLG appeared as small, round, hyporeflective structures. SLG were encountered most often in eyes with neovascular age-related macular degeneration (AMD) that had type 1 macular neovascularization (MNV) (91.1%). Of those eyes, 93.3% were receiving intravitreal antivascular endothelial growth factor (VEGF) therapy (median of 15 injections) with a mean follow-up of 52.6months. The number of prior injections positively correlated with the number of SLG. The detection of MNV preceded the presence of SLG in 66.7% of cases. En face OCT showed that, in many eyes (49%), SLG appeared in clusters of >10. In 38.8% of eyes, SLG were found overlying type 1 MNV, and in 44.9% of eyes, often those with more numerous SLG, the SLG were located near the lesion border. In 2 eyes with AMD followed for nonexudative type 1 MNV, SLG were detected prior to the detection of other imaging signs of exudation. SLG were observed in several other exudative macular diseases. Phantom models demonstrated that the hypertransmission tail beneath SLG is related to a lensing effect produced by these hyporeflective spherical structures. SLG are a newly recognized OCT feature frequently seen in eyes receiving intravitreal anti-VEGF therapy for type 1 MNV due to AMD. OCT B-scans show SLG as small, round, hyporeflective structures with a characteristic hypertransmission tail. This OCT signature is influenced by the OCT focal plane, and it relates to reduced signal attenuation through oil and a lensing effect created by a higher refractive index compared to surrounding tissue.

Case report: the first case of unilateral retinal pigment epithelium dysgenesis in China

BackgroundUnilateral retinal pigment epithelium dysgenesis (URPED) is a rare condition and is characterized by a unilateral and solitary lesion in the peripapillary region. The lesion presents with central atrophy, peripheral fibrosis, and hyperplastic changes in the retinal pigment epithelium (RPE). Herein, we report the first case of URPED in a Chinese individual using multimodal imaging techniques such as en-face optical coherence tomography (OCT) and optical coherence tomography angiography (OCTA).Case presentationA 10-year-old girl presented with 20/40 vision in her left eye. Presented as a solitary, unilateral, large and yellowish-white lesion, with fringe-like margins was observed in the posterior pole and lower middle periphery of the left eye continuous with the optic nerve, indicated URPED. Infrared fundal (IR) images showed that the fringe-like contour of the lesion was visible, with diffuse hyperreflective signals specifically in the fovea, while with peripheral dark spots, having a typical leopard-spot like appearance. Fundus autofluorescence (FAF) revealed a markedly scalloped lesion containing a hypoautofluorescence area mixed with an isoautofluorescence area. Spectral-domain optical coherence tomography (SD-OCT) revealed the outer segments of photoreceptors presented with an inhomogeneous signal in the fovea, with a weak local signal. The ellipsoid and interdigitation zones were thinner than normal, while the RPE/Bruch’s complex was not flat, with locally visible protrusions. En-face OCT image at the level of the RPE zone showed a mottled hyperreflective signal with peripheral hyporeflective spots, fringe-like margin lesions. OCTA of the avascular area of the fovea in the superficial, deep, and outer retinal layers appeared to be oval in shape, the choroid capillary layer revealed an increase in the density of the choroidal vasculature in the fovea.ConclusionsThis is the first report on URPED in China. Both en-face OCT and OCTA were essential in observing and studying the disease. Further investigation is required to better define the en-face OCT and OCTA features of URPED and clarify the disease characteristics and prognosis.

The prognostic value of total macular external limiting membrane and ellipsoid zone damage for clinical outcome in treatment-resistant neovascular age-related macular degeneration.

To examine the prognostic value of the extent of damage to the ellipsoid zone (EZ) and external limiting membrane (ELM) in response to the treatment of age-related macular degeneration (AMD) eyes switched from ranibizumab to aflibercept. This is a retrospective study of patients with neovascular AMD resistant to ranibizumab defined as having persistent intra- or subretinal fluid on OCT scans despite at least 6-month treatment and switched to aflibercept. Clinical data was collected and quantitative measurements of the area of EZ and ELM damage were obtained, on en-face optical coherence tomography images, at the time of switch to aflibercept (baseline) and up to 6months of follow-up. The study included 71 eyes (52.1% right eye) of 71 patients. At baseline, there was a correlation between the size of the EZ and ELM damaged area and BCVA (R=-0.39, p=0.001 and R=-0.47, p<0.001, respectively). The EZ and ELM damaged areas maintained correlation with BCVA at 6months (R=-0.28, p=0.01 and R=-0.39, p=0.001, respectively). Central retinal thickness did not correlate with BCVA at the time of switch (p=0.38) or at 6months (p=0.36). The extent of damage to the EZ and ELM correlates with BCVA following a switch in treatment.

Effects of Induced Astigmatism on Spectral Domain-OCT Angiography Quantitative Metrics

To analyze the effect of induced astigmatism on en-face spectral-domain optical coherence tomography angiography quantitative metrics. Prospective crossover study. Normal eyes without astigmatism and with 0.75, 1.75, and 2.75 diopters (D) of with-the-rule (WTR) astigmatism were imaged using a 3× 3-mm scan pattern SD-OCTA CIRRUS 5000 HD-OCT with AngioPlex (Carl Zeiss Meditec, Dublin, CA, USA). Quantitative parameters, including foveal avascular zone metrics, parafoveal vessel length density (VD), and perfusion density (PD) were corrected for magnification secondary to axial length and analyzed. Univariate linear regressions were performed within each eye to correlate quantitative metrics to the level of an induced astigmatic cylinder. Fifteen eyes from 15 patients were imaged. Every 1-D increase in induced WTR astigmatism was associated with a statistically significant decrease in VD and PD within all Early Treatment Diabetic Retinopathy Study inner ring quadrants; however, especially more so nasally (VD: 0.63; P < .001; PD: 0.0089; P= .001). For every 1-D increase in induced astigmatism, the resulting decrease in the inner ring superior quadrant was 12% greater for VD and 16% greater for PD versus that in the inferior quadrant. The resulting decrease in the inner ring nasal quadrant was 40% greater for VD and 48% greater for PD versus that in the temporal quadrant. Increasing levels of induced WTR astigmatism correlated with globally diminishing VD and PD, was more symmetrical for vertical than horizontal quadrants, and was most pronounced nasally. This may be due to a high prevalence of horizontally oriented vessels nasally and the horizontal optical defocus induced by WTR astigmatism.

Localization of Anatomical Features in Vascular-enhanced Enface OCT Images.

Optical coherence tomography (OCT) allows in vivo volumetric imaging of the eye. Identification and localization of anatomical features in enface OCT are important steps in OCT-based image analysis. However the visibility of anatomical features in both structural OCT or vascular OCT angiography is limited. In this paper, we propose to use vascular-enhanced enface OCT image for the concurrent detection of anatomical features, using a FasterRCNN object detection framework based on convolutional networks. Transfer learning was applied to adapt pre-trained models as the backbone networks. Models were evaluated on a dataset of 419 images. The results showed that VGG-FasterRCNN achieved a mean average precision 0.77, with localization errors of 0.18 ± 0.10 mm and 0.24 ± 0.13 mm for the macula and optic disc respectively. The results are promising and suggest that this network could potentially be used to automatically and concurrently detect anatomical features.Clinical Relevance- Localization of anatomical features in enface OCT is needed for the automation of OCT image analysis protocols. The use of fast detection networks could potentially suggest image-based real-time tracking during image acquisition.