Retinal Area Research Articles

Susac syndrome: A rare presentation

Susac syndrome is an autoimmune microangiopathy characterized by a triad of encephalopathy, sensori-neural hearing loss and varying degrees of branch retinal artery occlusion. A young male patient is described with features of focal neurological lesions and small superficial retinal haemorrhages and areas of retinal arteriolar endothelial inflammation appearing as Gass plaques. Susac syndrome presents with varying features involving brain, inner ear and retina. Fundus Fluorescein angiography should be performed in all patients with an unexplained encephalopathy to look for characteristic arteriolar wall changes.

Analysis of optical coherence tomography of the optic nerve head and of the retinal macular area in multiple sclerosis patients

BACKGROUND: Multiple sclerosis is a chronic autoimmune demyelinating disease of the central nervous system. Early diagnosis of the disease is extremely important for the just-in-time start of specific therapy. Optical coherence tomography (OCT) of the optic nerve head and retina can become an early marker of the neurodegenerative process in multiple sclerosis.
 AIM: To determine OCT-changes in the retinal nerve fiber layer (RNFL) thickness and retinal thickness in the macular area being most specific for multiple sclerosis.
 MATERIALS AND METHODS: 197 patients were examined, the study group consisted of 136 patients (274 eyes) with an established diagnosis of multiple sclerosis and the disease duration of at least 6 months. The control group included 61 healthy people (122 eyes). All patients underwent a standard ophthalmological examination, OCT was performed on Spectralis OCT (Heidelberg Engineering, Germany) using 2 scanning protocols: ONH-RC-Scan (Optic Nerve Head-Radial Circle Scan) and PPAA (Posterior Pole Asymmetry Analysis)
 RESULTS: Only 11 patients (8.1%) had a history of retrobulbar neuritis, the best corrected visual acuity was 0.7 and higher in 83 (81%) patients with multiple sclerosis, while the optic nerve head and retinal nerve fiber layer OCT-changes typical for multiple sclerosis were found in 118 patients (87%). The most prominent thinning of the retinal nerve fiber layer in group with multiple sclerosis was revealed in the temporal part of the optic nerve head (59.9 14.8 in the study group versus 76.6 12.0 in the control group; p 0.001), the least thinning was in the nasal half (66.6 14.3 in the study group versus 69.3 12.4 in the control group; p = 0.013). The retina in the macular area in multiple sclerosis patients was thinned over the entire area, the most significant changes were in the Outer Nasal 7 zone (303.3 20.4 in the study group versus 324.3 10.0 in the control group; p 0.001). Cluster analysis found 6 new retinal zones for mapping the macular area using the scanning protocol PPAA. In order to determine the prognostic value of the obtained zones, a logistic regression model was constructed, which with a sensitivity of 87.1% and a specificity of 81.6% allows concluding on the probability of having multiple sclerosis.
 CONCLUSION: OCT data using the proposed mapping of the macular area with the mathematical model analysis could be used to diagnose specific optic nerve atrophy, to reveal typical thinning of the retinal nerve fiber layer associated with multiple sclerosis, and in the long run, to become an additional criterion for establishing the diagnosis of multiple sclerosis.

Inflammatory cytokines and retinal nonperfusion area in quiescent proliferative diabetic retinopathy.

We sought to investigate the association between inflammatory cytokine levels and retinal capillary nonperfusion area in eyes with quiescent proliferative diabetic retinopathy (PDR). Samples of aqueous humor were collected from 67 eyes (n = 42 patients) with treatment-naïve PDR. Levels of interleukin (IL)-10, IL-1β, IL-6, IL-8, monocyte chemoattractant protein 1 (MCP-1), and tumor necrosis factor-α (TNF-α) were obtained using multiplex bead assay. Areas of capillary nonperfusion at the posterior pole and peripheral retina were measured via ultra-widefield fluorescein angiography and correlated with cytokine levels. The levels of IL-10, IL-6, IL-8, MCP-1, and TNF-α were positively correlated with the nonperfusion area of the peripheral retina (r = 0.298, 0.401, 0.265, 0.435, and 0.393; all P ≤ 0.030). There were positive correlations between IL and 10, IL-6, IL-8, MCP-1, and TNF-α (all R ≥ 0.247; all P ≤ 0.043). IL-1β did not show a significant correlation with the nonperfusion area (P = 0.972 for posterior pole and 0.392 for periphery) but was positively correlated with TNF-α (r = 0.334; P = 0.006). An increased level of inflammation was observed in PDR eyes with larger nonperfusion areas, which suggests inflammation as a possible target for suppressing PDR progression associated with nonperfusion.

Chronic Chemogenetic Activation of the Superior Colliculus in Glaucomatous Mice: Local and Retrograde Molecular Signature.

One important facet of glaucoma pathophysiology is axonal damage, which ultimately disrupts the connection between the retina and its postsynaptic brain targets. The concurrent loss of retrograde support interferes with the functionality and survival of the retinal ganglion cells (RGCs). Previous research has shown that stimulation of neuronal activity in a primary retinal target area—i.e., the superior colliculus—promotes RGC survival in an acute mouse model of glaucoma. To build further on this observation, we applied repeated chemogenetics in the superior colliculus of a more chronic murine glaucoma model—i.e., the microbead occlusion model—and performed bulk RNA sequencing on collicular lysates and isolated RGCs. Our study revealed that chronic target stimulation upon glaucomatous injury phenocopies the a priori expected molecular response: growth factors were pinpointed as essential transcriptional regulators both in the locally stimulated tissue and in distant, unstimulated RGCs. Strikingly, and although the RGC transcriptome revealed a partial reversal of the glaucomatous signature and an enrichment of pro-survival signaling pathways, functional rescue of injured RGCs was not achieved. By postulating various explanations for the lack of RGC neuroprotection, we aim to warrant researchers and drug developers for the complexity of chronic neuromodulation and growth factor signaling.

Intraocular reflectance of the ocular fundus and its impact on increased retinal hazard

PurposeInside the eye light can be reflected multiple times due to light-tissue interactions and the spherical geometry of the eye. Due to these optical properties, a defined retinal area is not only illuminated by direct light but also by indirect, reflected light from the inner side of the eyewall. During illumination for ophthalmic surgery, this could lead to an unintended increase in intraocular retinal irradiance, which was already discussed in previous studies but without a detailed consideration of spectral differences and a potential influence of pigmentation. In this study this effect is investigated wavelength-dependent to see if different wavelengths lead to different increase in irradiance, with a special focus on the raise in photochemical and thermal hazard to the retina. It is also examined whether this effect is dependent on the pigmentation of the eye. MethodsThe reflectance properties of either less or highly pigmented porcine eyes are measured in the wavelength range between 350 and 1100nm with an integrating sphere and a spectrometer. With these reflectance spectra the wavelength-dependent Sphere Multiplier M of porcine eyes can be calculated, which represents the increase of radiance due to multiple reflections inside a sphere compared to a planar diffuser of the same size. Based on measurements of the emitted irradiance of ophthalmic illumination fibers the increase in photochemical and thermal retinal hazard due to these multiple reflections is calculated for eyes with small and high amounts of pigmentation. ResultsThe reflectance of the inner eyewall in the range between 350 and 1100nm is significantly higher for eyes with low pigmentation (between 4.90% and 37.44% reflectance) in comparison to eyes with a high amount of pigmentation (between 4.30% and 28.88% reflectance). The Sphere Multiplier for the inner side of the eyewall (sclera, choroid and retina) ranges between 1.13 and 1.59 and between 1.13 and 1.48 for eyes with low and high pigmentation, respectively, in the range between 350 and 1100nm. The reflectance, as well as the Sphere Multiplier, is strongly wavelength-dependent due to the absorption spectra of melanin and hemoglobin, which are located in the eye. With increasing wavelength, the reflection properties and the Sphere Multiplier also increases. With this, the photochemical retinal hazard of highly pigmented eyes increases by (14.11± 0.09)% and of lightly pigmented eyes by (16.75±0.35)% compared to if the reflection properties are not considered. The thermal retinal hazard increases by (14.30±0.07)% for highly pigmented eyes and by (19.65±0.17)% for low pigmented eyes. ConclusionThis study demonstrates that the anatomy and pigmentation of the eye plays an important role for the reflectance properties of the eye and for the photochemical and thermal hazard to the retina.

Late contralateral recurrence of retinal detachment in incontinentia pigmenti: A case report

BACKGROUNDIncontinentia pigmenti (IP) is a rare X-linked genetic disease. It mainly manifests as skin lesions and causes problems in the eyes, teeth, bones, and central nervous system. Of the various ocular manifestations, the most severe with difficult recovery is retinal detachment (RD). Here, we report an unusual case of bilateral asymmetrical RD. CASE SUMMARYWe present the case of an 11-year-old Chinese girl with IP who complained of sudden blurring of vision in the left eye. At that time, she had been blind in her right eye for 4 years. RD with traction was observed in both eyes. A massive retinal proliferative membrane, exudation, and hemorrhage were seen in the left eye. We performed vitrectomy in her left eye. Her visual acuity recovered to 20/50, and her retina had flattened within 2 d after surgery. During the 3-mo follow-up, we performed retinal laser treatment of the non-perfused retinal area in her left eye. Eventually, her visual acuity returned to 20/32, and no new retinal abnormalities developed. CONCLUSIONIn patients with IP with fundal abnormalities in one eye, it is important to focus on the rate of fundal change in the other eye. RD in its early stages can be effectively treated with timely vitrectomy and laser photocoagulation.

Association between blood-aqueous barrier disruption and extent of retinal detachment.

To investigate the association between anatomical features of rhegmatogenous retinal detachment (RRD) and the extent of blood-aqueous barrier disorder measured by non-invasiv laser flare photometry. Retrospective evaluation of consecutive patients with RRD that underwent surgery between November 2016 and October 2018. Descriptive evaluation of pre- and postoperative parameters and correlation to preoperative laser flare value, extent of retinal detachment and re-detachment rate were performed. 266 patients (mean age 62.73 ± 10.40 years, 62.8% male) were included. Mean preoperative flare value was 11.0 ± 11.9 pc/ms. In pseudophakia flare values were higher than in phakia (12.7 ± 10.4 pc/ms versus 9.8 ± 12.9 pc/ms; p = 0.042). Flare increased and correlated significantly with the number of affected retinal quadrants (Q) (1 Q 6.4 ± 3.3 pc/ms; 2 Q 10.5 ± 8.8 pc/ms; 3 Q 15.6 ± 9.1 pc/ms; 4 Q 27.5 ± 33.3 pc/ms; p < 0.001; r = 0.40). Macular status correlated significantly with flare values (macula on 8.6 ± 7.1 pc/ms, off 13.1 ± 15.0 pc/ms; p = 0.004; r = 0.17). The level of objective tyndallometry in RRD seems to be influenced by lens status and extent of retinal detachment. Thus, the greater the affected retinal area is, the more blood-aqueous barrier disruption seems to be present.

Thioredoxin-1 Ameliorates Oxygen-Induced Retinopathy in Newborn Mice through Modulation of Proinflammatory and Angiogenic Factors.

Oxygen-induced retinopathy (OIR) is an animal model for retinopathy of prematurity, which is a leading cause of blindness in children. Thioredoxin-1 (TRX) is a small redox protein that has cytoprotective and anti-inflammatory properties in response to oxidative stress. The purpose of this study was to determine the effect of TRX on OIR in newborn mice. From postnatal day 7, C57BL/6 wild type (WT) and TRX transgenic (TRX-Tg) mice were exposed to either 21% or 75% oxygen for 5 days. Avascular and neovascular regions of the retinas were investigated using fluorescence immunostaining. Fluorescein isothiocyanate-dextran and Hoechst staining were used to measure retinal vascular leakage. mRNA expression levels of proinflammatory and angiogenic factors were analyzed using quantitative polymerase chain reaction. Retinal histological changes were detected using immunohistochemistry. In room air, the WT mice developed well-organized retinas. In contrast, exposing WT newborn mice to hyperoxia hampered retinal development, increasing the retinal avascular and neovascular areas. After hyperoxia exposure, TRX-Tg mice had enhanced retinal avascularization compared with WT mice. TRX-Tg mice had lower retinal neovascularization and retinal permeability during recovery from hyperoxia compared with WT mice. In the early stages after hyperoxia exposure, VEGF-A and CXCL-2 expression levels decreased, while IL-6 expression levels increased in WT newborn mice. Conversely, no differences in gene expressions were observed in the TRX-Tg mouse retina. IGF-1 and Angpt1 levels did not decrease during recovery from hyperoxia in TRX-Tg newborn mice. As a result, overexpression of TRX improves OIR in newborn mice by modulating proinflammatory and angiogenic factors.

Quantitative analysis of preclinical ocular microvascular changes in Multisystemic Inflammatory Syndrome in Children (MIS-C) detected by optical coherence tomography angiography.

ObjectivesTo evaluate the macular and optic nerve head (ONH) vascular density, foveal avascular zone area, and outer retina and choriocapillaris flow in Multisystemic Inflammatory Syndrome in Children (MIS-C) using optical coherence tomography angiography (OCTA).MethodsThirty-four eyes of 34 patients with MIS-C and 36 age and sex-matched healthy controls were investigated in this prospective, cross-sectional study. The superficial capillary plexus (SCP) and deep capillary plexus (DCP), ONH, FAZ parameters, the flow area of the outer retina, and choriocapillaris were evaluated using OCTA.ResultsAll VD parameters in SCP were significantly lower in MIS-C patients. There was no significant difference between the groups in VD parameters of both DCP and ONH, as well as FAZ area and FAZ perimeter. However, foveal density (FD-300) was significantly decreased in the MIS-C group. (p = 0.024). The outer retina flow area at 1 mm, 2 mm, and 3 mm radius and CC flow area at 1 mm and 2 mm radius were significantly lower in the MIS-C group than in the control group. Although CC flow area at 3 mm radius was decreased in the MIS-C group compared to healthy controls, the difference was not statistically significant.ConclusionsWe demonstrated a decreased vessel density in SCP, choriocapillaris flow area, and outer retinal flow area in MIS-C patients. Hence, we proposed that OCTA could reveal retinal and choroidal microvascular changes in MIS-C patients who were completely healthy before the diagnosis of MIS-C.

Elabela promotes the retinal angiogenesis by inhibiting ferroptosis during the vaso-obliteration phase in mouse oxygen-induced retinopathy model.

Retinopathy of prematurity (ROP) is a leading cause of childhood blindness associated with retinal vaso-obliteration in phase 1 and pathological neovascularization (NV) in phase 2; however, effective and safe treatments for ROP definitive treatment are yet to be determined. Anti-vascular endothelial growth factor (VEGF) therapy mainly focuses on reducing abnormal NV in phase 2 but with high risks of late recurrence and systemic side effects. Previous studies have established that the severity of vaso-obliteration in phase 1largely influences subsequent stages, suggesting that prevention of vessels loss may be a potential therapeutic target for ROP. Herein, the therapeutic potential and safety of early Elabela intervention treatment in treating phase 1 ROP and the possible underlying mechanisms were investigated using an oxygen-induced retinopathy (OIR) mouse model. It was observed that intraperitoneal injection of Elabela remarkably reduced the avascular retinal area and increased the vascular density in phase 1 of OIR mice. Further investigation revealed that mitochondrion-dependent ferroptosis was involved in oxidative stress-mediated vascular protection loss in phase 1 OIR. Furthermore, we demonstrated that Elabela could rescue mitochondria-dependent ferroptosis via mediating the xCT/GPX4 axis. Collectively, our study revealed that ferroptosis may play a significant role in early ROP, while Elabela may be a safe and promising strategy for the early intervention of ROP.

Retinal Changes in Astrocytes and Müller Glia in a Mouse Model of Laser-Induced Glaucoma: A Time-Course Study.

Macroglia (astrocytes and Müller glia) may play an important role in the pathogenesis of glaucoma. In a glaucoma mouse model, we studied the effects of unilateral laser-induced ocular hypertension (OHT) on macroglia in OHT and contralateral eyes at different time points after laser treatment (1, 3, 5, 8 and 15 days) using anti-GFAP and anti-MHC-II, analyzing the morphological changes, GFAP-labelled retinal area (GFAP-PA), and GFAP and MHC-II immunoreactivity intensities ((GFAP-IRI and MHC-II-IRI)). In OHT and contralateral eyes, with respect to naïve eyes, at all the time points, we found the following: (i) astrocytes with thicker somas and more secondary processes, mainly in the intermediate (IR) and peripheral retina (PR); (ii) astrocytes with low GFAP-IRI and only primary processes near the optic disc (OD); (iii) an increase in total GFAP-RA, which was higher at 3 and 5 days, except for at 15 days; (iv) an increase in GFAP-IRI in the IR and especially in the PR; (v) a decrease in GFAP-IRI near the OD, especially at 1 and 5 days; (vi) a significant increase in MHC-II-IRI, which was higher in the IR and PR; and (vii) the Müller glia were GFAP+ and MHC-II+. In conclusion, in this model of glaucoma, there is a bilateral macroglial activation maintained over time involved in the inflammatory glaucoma process.

Differences in Mean Values and Variance in Quantitative Analyses of Foveal OCTA Imaging.

Multiple approaches for quantifying parameters such as vessel density (VD) and vessel length density (VLD) in optical coherence tomography angiography (OCTA) en-face segmentations are currently available. While it is common knowledge that data gathered from different methods should not be directly compared to each other, a comparison of the different methods can help to further the understanding of differences between different methods of measurement. Here we compare a common method of semiautomatically quantifying VD and VLD with an automated method supplied by the manufacturer of an OCTA device and report on differences in performance in order to probe for and highlight differences in values gathered by both methods. OCTA was performed using the swept source PLEX Elite 9000 device, software version 2.0.1.47652 (Carl Zeiss Meditec Inc., Dublin, CA, USA). Scans of 3 mm × 3 mm from healthy volunteers centred on the fovea were acquired by a well-trained certified ophthalmologist. Scans with a signal strength of 8 out of 10 or higher were included. Quantitative parameters of the 3 mm × 3 mm cube scans were automatically generated and segmented into superficial capillary plexus (SCP) and deep capillary plexus (DCP) layers using layer segmentation produced by the instrument software and prototype analysis VD quantification software (Macular Density v.0.7.1, ARI Network Hub, Carl Zeiss Meditec Inc., Dublin, CA, USA) supplied by the manufacturer. An alternative approach of quantitative analysis of VD and VLD was performed manually with ImageJ (National Institutes of Health, Bethesda, Maryland, USA), as previously reported. VD was assessed as the ratio of the retinal area occupied by vessels. VDL was measured as the total length of the skeletonised vessels using 1-pixel centre line extraction of the blood vessels. We report differences in standard deviation (SD) in OCTA parameters obtained using different methods. The standard deviation of VD and VLD measurements was statistically significantly different in VD of 3 mm × 3 mm DCP (p = 0.009), VLD of 3 mm × 3 mm SCP (p = 0.000), and VLD of 3 mm × 3 mm DCP (p = 0.021). No statistically significant differences were found in VD of 3 mm × 3 mm SCP (p = 0.128) or VLD of 3 mm × 3 mm SCP (p = 0.107). As expected, we were able to demonstrate significant differences in quantitative OCTA parameters gathered from the same images using different methods of quantification. Values gathered using different methods are not interchangeable. In scientific studies and in situations where long-term follow-up is necessary, the same device and the same method of quantification should be used to maintain retrospective comparability of measurements.

Retinal Tacks for Complicated Retinal Detachment: Retinal Tacks in the Times of Modern Small-Gauge Vitrectomy.

Purpose To investigate the efficacy and safety profile of retinal tacks (RTs) in cases of retinal detachment (RD) with advanced proliferative vitreoretinopathy (PVR). Materials and Methods In this single-center, retrospective study medical record, optical coherence tomography and ultra-widefield fundus images of patients with complex PVR-related and RT surgery were reviewed. All cases underwent 23G pars plana vitrectomy (PPV), RT implantation, retinectomy, circumferential intraoperative laser retinopexy, and silicone oil tamponade. Results Fourteen eyes of 14 patients with complex rhegmatogenous RD with PVR were included: 7 cases showed PVR grade C type P and 7 combined grades A and P. RTs were positioned at contracted, stiffened retinal areas to achieve attachment of retinectomy borders after extensive PVR peeling. Patients underwent on an average of 1.3 PPVs (range 0–3) prior RT surgery. An average of 2.5 RTs (range 1–4) were implanted. Only in a single eye, a recurrent RD occurred. In 10 eyes, the silicone oil tamponade was still in place at the last follow-up. In 5 eyes, the silicone oil could be removed without redetachment in all of these cases (average of 31.3 weeks, range 11.4–53). No RT-related intraoperative or postoperative complications like dislocation or bleedings were observed. Conclusion RTs have the potential to improve the treatment of complex PVR-associated RD. RT can be a useful surgical tool to reattach borders of retinectomies in advanced PVR. No RT-associated complication were observed in this study.

Retinal Capillary Damage Is Already Evident in Patients With Hypertension and Prediabetes and Associated With HbA1c Levels in the Nondiabetic Range.

We analyzed whether any change in capillary density in the retinal circulation could be detected in patients with hypertension in the prediabetic stage. In a cross-sectional analysis, we assessed capillary density in the foveal (CDF) and parafoveal retinal areas using optical coherence tomography-angiography in 62 patients with hypertension and normal glucose metabolism and 40 patients with hypertension and prediabetes. The CDF was lower in patients with prediabetes than in those with normal glucose metabolism. Moreover, we found a correlation between CDF and HbA1c and glucose levels for the entire cohort. In patients with HbA1c <6.5% (48 mmol/mol), CDF was lower in patients with HOMA for insulin resistance (HOMA-IR) ≥2.5 than in patients with HOMA-IR <2.5. Patients with hypertension and prediabetes display retinal capillary changes, and an association with markers of glucose metabolism exists, even within a nondiabetic HbA1c range.

Baseline retinal vascular bed area on ultra-wide field fluorescein angiography correlates with the anatomical outcome of diabetic macular oedema to ranibizumab therapy: two-year analysis of the DAVE Study.

To determine the relationship between baseline retinal non-perfusion area (NPA) and retinal vascular bed area (RVBA) on ultra-wide field fluorescein angiography (UWF FA) and long-term response to intravitreal ranibizumab therapy in diabetic macular oedema (DMO). A post-hoc, 2-year observational case series. Baseline UWF FA images (Optos 200Tx) of 40 eyes from 29 patients with diabetes mellitus and treatment naïve DMO in the DAVE (NCT01552408) study were montaged and stereographically projected at the Doheny Image Reading Center to adjust for peripheral distortion. The retinal vasculature was automatically extracted to calculate RVBA. NPA was manually delineated by two masked certified graders. RVBA and NPA were computed in mm2 automatically by adjusting for peripheral distortion and then correlated with the severity of DMO. While global NPA at baseline was not correlated to retinal thickness measurements, baseline NPA in the superior retina was associated with the macular volume (MV) improvement (P = 0.022). Multivariate analysis revealed a smaller RVBA at baseline was correlated with a better MV outcome at two-year follow-up after adjusting for confounding factors (P = 0.049). Eyes with smaller baseline RVBA appear to have a better long-term anatomic outcome of DMO.

Retinal Microvascular Changes in Patients with Multiple Myeloma: A Study Based on Optical Coherence Tomography Angiography

Purpose: Ocular microvascular networks and variables were analyzed using optical coherence tomography angiography (OCTA) in patients with multiple myeloma (MM) who had no pathological findings in their routine ophthalmologic examinations. Methods: The study included 31 patients with a diagnosis of MM and 30 healthy controls. The ophthalmologic examination findings and OCTA measurements of the participants were prospectively analyzed. We evaluated the superficial capillary plexus (SCP) vessel density (VD) and deep capillary plexus (DCP) VD in macular region, radial peripapillary capillary (RPC) VD, optic nerve head (ONH) VD and the foveal avascular zone (FAZ) area. Results: The samples were gender-balanced, and there were no significant differences in age or gender between the MM and control groups. From the OCTA, all the ONH-VD measurements, except for the peripapillary and superotemporal parameters, were found to be significantly lower in MM patients than in the control group; the same was found for the whole image, inferonasal, superonasal, and superotemporal RPC-VD values; for all the SCP-VD values, except for the inferior hemi and temporal; and for all the DCP-VD values. It was also observed that the deep FAZ area was wider in the MM group than in the control group. Conclusions: We detected decreased VD in deep and superficial macular retinal areas, papillary, peripapillary regions, suggesting decreased blood flow and possible ischemia in MM patients. Therefore, obtaining information on ischemia by using a noninvasive and easily measurable method such as OCTA, may be beneficial in terms of follow-up and treatment but this needs to be supported by further, larger studies.

Study of Nonperfusion Area Changes after Ranibizumab Intravitreal Injection for Diabetic Macular Edema by Means of Widefield OCT Angiography

Introduction: The aim of this study was to evaluate changes in retinal capillary nonperfusion areas (RCNPA) and the retinal capillary vessel density (RCVD) of the superficial capillary plexus (SCP) and deep capillary plexus (DCP) using widefield optical coherence tomography angiography (WFOCTA) in patients with diabetic retinopathy (DR) and diabetic macular edema (DME) treated with intravitreal ranibizumab injection (IRI). Materials and Methods: Twenty-four eyes of 24 patients with DR and DME candidates to a loading dose of IRI were enrolled. All patients underwent WFOCTA with the PLEX Elite 9000 device with 15 × 9 mm scans centered on the foveal center at baseline (T0) and 1 month after each intravitreal injection at 30 days (T1), 60 days (T2), and 90 days (T3). In all patients, the variation of RCNPA and the RCVD of the SCP and DCP were calculated using automatic software written in MATLAB (MathWorks, Natick, MA, USA). Results: The SCP showed a significant longitudinal variation of RCNPA (p = 0.04). Post hoc analysis revealed a statistically significant reduction of RCNPA at T1 (p = 0.04) and a nonsignificant reduction at T2 (p = 0.18) and T3 (p = 0.96). The DCP showed longitudinal changes in the RCNPA that tended to statistical significance (p = 0.09). Post hoc analysis revealed a trend toward a statistically significant reduction of RCNPA at T3 (p = 0.09) not statistically significant at T1 (p = 0.17) and T2 (p = 0.75). The RCVD of SCP and DCP showed no significant changes at any of the time points. Conclusions: WFOCTA showed a decrease in RCNPA after IRI, probably related to the reperfusion of retinal capillaries.

Subretinal Implantation of Human Primary RPE Cells Cultured on Nanofibrous Membranes in Minipigs.

Purpose: The development of primary human retinal pigmented epithelium (hRPE) for clinical transplantation purposes on biodegradable scaffolds is indispensable. We hereby report the results of the subretinal implantation of hRPE cells on nanofibrous membranes in minipigs. Methods: The hRPEs were collected from human cadaver donor eyes and cultivated on ultrathin nanofibrous carriers prepared via the electrospinning of poly(L-lactide-co-DL-lactide) (PDLLA). “Libechov” minipigs (12–36 months old) were used in the study, supported by preoperative tacrolimus immunosuppressive therapy. The subretinal implantation of the hRPE-nanofibrous carrier was conducted using general anesthesia via a custom-made injector during standard three-port 23-gauge vitrectomy, followed by silicone oil endotamponade. The observational period lasted 1, 2, 6 and 8 weeks, and included in vivo optical coherence tomography (OCT) of the retina, as well as post mortem immunohistochemistry using the following antibodies: HNAA and STEM121 (human cell markers); Bestrophin and CRALBP (hRPE cell markers); peanut agglutining (PNA) (cone photoreceptor marker); PKCα (rod bipolar marker); Vimentin, GFAP (macroglial markers); and Iba1 (microglial marker). Results: The hRPEs assumed cobblestone morphology, persistent pigmentation and measurable trans-epithelial electrical resistance on the nanofibrous PDLLA carrier. The surgical delivery of the implants in the subretinal space of the immunosuppressed minipigs was successfully achieved and monitored by fundus imaging and OCT. The implanted hRPEs were positive for HNAA and STEM121 and were located between the minipig’s neuroretina and RPE layers at week 2 post-implantation, which was gradually attenuated until week 8. The neuroretina over the implants showed rosette or hypertrophic reaction at week 6. The implanted cells expressed the typical RPE marker bestrophin throughout the whole observation period, and a gradual diminishing of the CRALBP expression in the area of implantation at week 8 post-implantation was observed. The transplanted hRPEs appeared not to form a confluent layer and were less capable of keeping the inner and outer retinal segments intact. The cone photoreceptors adjacent to the implant scaffold were unchanged initially, but underwent a gradual change in structure after hRPE implantation; the retina above and below the implant appeared relatively healthy. The glial reaction of the transplanted and host retina showed Vimentin and GFAP positivity from week 1 onward. Microglial activation appeared in the retinal area of the transplant early after the surgery, which seemed to move into the transplant area over time. Conclusions: The differentiated hRPEs can serve as an alternative cell source for RPE replacement in animal studies. These cells can be cultivated on nanofibrous PDLLA and implanted subretinally into minipigs using standard 23-gauge vitrectomy and implantation injector. The hRPE-laden scaffolds demonstrated relatively good incorporation into the host retina over an eight-week observation period, with some indication of a gliotic scar formation, and a likely neuroinflammatory response in the transplanted area despite the use of immunosuppression.

Reference database of total retinal vessel surface area derived from volume-rendered optical coherence tomography angiography

Optical coherence tomography angiography (OCTA) enables three-dimensional, high-resolution, depth-resolved flow to be distinguished from non-vessel tissue signals in the retina. Thus, it enables the quantification of the 3D surface area of the retinal vessel signal. Despite the widespread use of OCTA, no representative spatially rendered reference vessel surface area data are published. In this study, the OCTA vessel surface areas in 203 eyes of 107 healthy participants were measured in the 3D domain. A Generalized Linear Model (GLM) model analysis was performed to investigate the effects of sex, age, spherical equivalent, axial length, and visual acuity on the OCTA vessel surface area. The mean overall vessel surface area was 54.53 mm2 (range from 27.03 to 88.7 mm2). OCTA vessel surface area was slightly negatively correlated with age. However, the GLM model analysis identified axial length as having the strongest effect on OCTA vessel surface area. No significant correlations were found for sex or between left and right eyes. This is the first study to characterize three-dimensional vascular parameters in a population based on OCTA with respect to the vessel surface area.

NEW BIOMARKER QUANTIFYING THE EFFECT OF ANTI-VEGF THERAPY IN EYES WITH PROLIFERATIVE DIABETIC RETINOPATHY ON ULTRAWIDE FIELD FLUORESCEIN ANGIOGRAPHY: RECOVERY Study.

To quantify changes of the retinal vascular bed area (RVBA) in mm2 on stereographically projected ultrawide field fluorescein angiography images in eyes with proliferative diabetic retinopathy after antivascular endothelial growth factor injection. This is a prospective, observational study. The early-phase ultrawide field fluorescein angiography images (Optos 200Tx) of 40 eyes with proliferative diabetic retinopathy and significant nonperfusion obtained at baseline and after six months (NCT02863354) were stereographically projected by correcting peripheral distortion. The global retinal vasculature on ultrawide field fluorescein angiography was extracted for calculating RVBA by summing the real size (mm2) of all the pixels automatically. For the entire cohort, the global RVBA for the entire retina decreased from 67.1 ± 15.5 to 43.6 ± 18.8 mm2 after anti-VEGF treatment at six months (P < 0.001). In the subgroup receiving monthly anti-VEGF injections, the global RVBA decreased from 68.7 ± 16.2 to 33.9 ± 13.3 mm2 (P < 0.001). In the subgroup receiving anti-VEGF every three months, the global RVBA decreased from 65.6 ± 15.1 to 50.8 ± 19.3 mm2 (P = 0.004). RVBA seems to be a new biomarker to indicate efficiency of retinal vascular changes after anti-VEGF injection. Eyes with proliferative diabetic retinopathy and significant nonperfusion demonstrate reduced RVBA after anti-VEGF treatment.