Retina

Single cell RNA sequencing studies identified novel neurodegeneration-associated microglial (MGnD/DAM) subtypes activated around cerebral amyloid plaques. Micro-RNA (miR)-155 of the TREM2-APOE pathway was shown to be a key transcriptional regulator of MGnD microglial phenotype. Despite growing interest in studying manifestations of Alzheimer's disease (AD) in the retina, a CNS organ accessible to noninvasive high-resolution imaging, to date MGnD microglia have not been studied in the AD retina. Here, we discovered the presence and increased populations of Clec7a+ and Galectin-3+ MGnD microglia in retinas of transgenic APPSWE/PS1L166P AD-model mice. Conditionally targeting MGnD microglia by miR-155 ablation via the tamoxifen-inducible CreERT2 system in APPSWE/PS1L166P mice diminished retinal Clec7a+ and Galectin-3+ microglial populations while increasing homeostatic P2ry12+ microglia. Retinal MGnD microglia were often adhering to microvessels; their depletion protected the inner blood-retina barrier and reduced vascular amyloidosis. Microglial miR-155 depletion further limits retinal inflammation. Mass spectrometry analysis revealed enhanced retinal PI3K-Akt signaling and predicted IL-8 and Spp1 decreases in mice with microglia-specific miR-155 knockout. Overall, this study identified MGnD microglia in APPSWE/PS1L166P mouse retina. Transcriptional regulation of these dysfunctional microglia mitigated retinal inflammation and vasculopathy. The protective effects of microglial miR-155 ablation should shed light on potential treatments for retinal inflammation and vascular damage during AD and other ocular diseases.

Purpose: To report a case of systemic diffuse large B cell lymphoma presenting with ocular manifestations and neurologic findings resembling Vogt-Koyanagi-Harada syndrome. Observations: A 51-year-old Caucasian man presented with headache, ear pain, and blurry vision in both eyes. He was found to have bilateral exudative retinal detachments. After a short period of initial improvement with high dose systemic corticosteroid, his condition significantly worsened. An extensive work-up, including a kidney biopsy, led to a diagnosis of systemic diffuse large B cell lymphoma. He had excellent recovery following treatment with appropriate chemotherapy. Conclusions and Importance: Systemic malignancy may present with ocular manifestations and may masquerade as another diagnosis. An unexpected clinical course may suggest an alternative diagnosis. A broad systemic work-up including an evaluation for malignancy should be considered for patients presenting with unexplained exam or systemic findings.

The optic nerve, like most pathways in the mature central nervous system, cannot regenerate if injured, and within days, retinal ganglion cells (RGCs), the neurons that extend axons through the optic nerve, begin to die. Thus, there are few clinical options to improve vision after traumatic or ischemic optic nerve injury or in neurodegenerative diseases such as glaucoma, dominant optic neuropathy, or optic pathway gliomas. Research over the past two decades has identified several strategies to enable RGCs to regenerate axons the entire length of the optic nerve, in some cases leading to modest reinnervation of di- and mesencephalic visual relay centers. This review primarily focuses on the role of the innate immune system in improving RGC survival and axon regeneration, and its synergy with manipulations of signal transduction pathways, transcription factors, and cell-extrinsic suppressors of axon growth. Research in this field provides hope that clinically effective strategies to improve vision in patients with currently untreatable losses could become a reality in 5-10 years.

BACKGROUND: Human-induced pluripotent stem cell-derived retinal organoids are a valuable tool for disease modelling and therapeutic development. Many efforts have been made over the last decade to optimise protocols for the generation of organoids that correctly mimic the human retina. Most protocols use common media supplements; however, protocol-dependent variability impacts data interpretation. To date, the lack of a systematic comparison of a given protocol with or without supplements makes it difficult to determine how they influence the differentiation process and morphology of the retinal organoids. METHODS: A 2D-3D differentiation method was used to generate retinal organoids, which were cultured with or without the most commonly used media supplements, notably retinoic acid. Gene expression was assayed using qPCR analysis, protein expression using immunofluorescence studies, ultrastructure using electron microscopy and 3D morphology using confocal and biphoton microscopy of whole organoids. RESULTS: Retinoic acid delayed the initial stages of differentiation by modulating photoreceptor gene expression. At later stages, the presence of retinoic acid led to the generation of mature retinal organoids with a well-structured stratified photoreceptor layer containing a predominant rod population. By contrast, the absence of retinoic acid led to cone-rich organoids with a less organised and non-stratified photoreceptor layer. CONCLUSIONS: This study proves the importance of supplemented media for culturing retinal organoids. More importantly, we demonstrate for the first time that the role of retinoic acid goes beyond inducing a rod cell fate to enhancing the organisation of the photoreceptor layer of the mature organoid.

Purpose: The guarded light pipe is a recently described alternative endoillumination technique to chandelier illumination. We sought to compare the outcomes of scleral buckling (SB) under indirect ophthalmoscopy (ID) to heads-up three-dimensional visualization with a guarded light pipe (3DGLP). Methods: A retrospective comparative study was performed, including 47 eyes that underwent SB for rhegmatogenous retinal detachment (RRD) repair with either traditional ID (n = 31) or 3DGLP (n = 16). Results: The single surgery anatomic success rate was 87.0% in the ID group and 87.5% in the 3DGLP group. The final anatomic success rate was 100% in both groups. The median (interquartile range) post-operative logMAR was 0.10 (0.0-0.20) in the ID group and 0.08 (0.02-0.69) in the 3DGLP group (p = 0.51). The median operative time was 107 (94-123) minutes in the ID group and 100 (90-111) minutes in the 3DGLP group (p = 0.25). Among eyes that underwent subretinal fluid drainage, the operative time was significantly longer in the ID group compared to the 3DGLP group, 113 (100-135) minutes vs 93 (85-111) minutes (p = 0.035). There were no post-operative complications in the ID group and one complication of self-resolving vitreous hemorrhage associated with a malfunctioning cryoprobe in the 3DGLP group (p = 0.34). There were no cases of post-operative cataract progression in either group. Conclusion: Compared to traditional SB, 3DGLP improves ergonomics and educational value with similar anatomical, visual, intra and post-operative outcomes and may result in shorter operative time in cases requiring subretinal fluid drainage.

PURPOSE OF REVIEW: The purpose of this review is to provide an overview of the ophthalmic findings associated with peripapillary hyperreflective ovoid mass-like structures (PHOMS) in both adult and pediatric patients. RECENT FINDINGS: PHOMS have recently been identified in a number of different ophthalmic disease entities ranging from nonpathologic to pathologic, including but not limited to anatomic abnormalities (tilting in myopia), optic nerve head drusen, optic disc edema from inflammation (optic neuritis, white dot syndromes), vascular insults (ischemic optic neuropathy, retinal vascular occlusion), and papilledema. The mechanism underlying the formation of PHOMS has not been fully elucidated although it has been hypothesized that PHOMS occur secondary to axoplasmic stasis from crowding at the optic nerve head. SUMMARY: Although the clinical significance of the presence of PHOMS remains unclear, PHOMS are associated with several disease processes. Understanding the mechanism behind their formation and their impact on optic nerve head structure and visual function may be relevant in patients with optic nerve head pathology. The presence of PHOMS may also correlate with disease severity and duration. Future studies to evaluate whether the formation of PHOMS may be useful as an early indicator of disease or a prognostic tool are warranted.

Non-invasive electric stimulation (ES) employing a low-intensity electric current presents a potential therapeutic modality that can be applied for treating retinal and brain neurodegenerative disorders. As neurons are known to respond directly to ES, the effects of ES on glia cells are poorly studied. A key question is if ES directly mediates microglial function or modulates their activity merely via neuron-glial signaling. Here, we demonstrated the direct effects of ES on microglia in the BV-2 cells-an immortalized murine microglial cell line. The low current ES in a biphasic ramp waveform, but not that of rectangular or sine waveforms, significantly suppressed the motility and migration of BV-2 microglia in culture without causing cytotoxicity. This was associated with diminished cytoskeleton reorganization and microvilli formation in BV-2 cultures, as demonstrated by immunostaining of cytoskeletal proteins, F-actin and β-tubulin, and scanning electron microscopy. Moreover, ES of a ramp waveform reduced microglial phagocytosis of fluorescent zymosan particles and suppressed lipopolysaccharide (LPS)-induced pro-inflammatory cytokine expression in BV-2 cells as shown by Proteome Profiler Mouse Cytokine Array. The results of quantitative PCR and immunostaining for cyclooxygenase-2, Interleukin 6, and Tumor Necrosis Factor-α corroborated the direct suppression of LPS-induced microglial responses by a ramp ES. Transcriptome profiling further demonstrated that ramp ES effectively suppressed nearly half of the LPS-induced genes, primarily relating to cellular motility, energy metabolism, and calcium signaling. Our results reveal a direct modulatory effect of ES on previously thought electrically "non-responsive" microglia and suggest a new avenue of employing ES for anti-inflammatory therapy.

PURPOSE: To report practice patterns of intravitreal injections of anti-VEGF for retinopathy of prematurity (ROP) and outcomes data with a focus on retreatments and complications. DESIGN: Multicenter, international, retrospective, consecutive series. SUBJECTS: Patients with ROP treated with anti-VEGF injections from 2007 to 2021. METHODS: Twenfty-three sites (16 United States [US] and 7 non-US) participated. Data collected included demographics, birth characteristics, examination findings, and methods of injections. Comparisons between US and non-US sites were made. MAIN OUTCOME MEASURES: Primary outcomes included number and types of retreatments as well as complications. Secondary outcomes included specifics of the injection protocols, including types of medication, doses, distance from limbus, use of antibiotics, and quadrants where injections were delivered. RESULTS: A total of 1677 eyes of 918 patients (43% female, 57% male) were included. Mean gestational age was 25.7 weeks (range, 21.2-41.5 weeks), and mean birth weight was 787 g (range, 300-2700 g). Overall, a 30-gauge needle was most commonly used (51%), and the quadrant injected was most frequently the inferior-temporal (51.3%). The distance from the limbus ranged from 0.75 to 2 mm, with 1 mm being the most common (65%). Bevacizumab was the most common anti-VEGF (71.4%), with a dose of 0.625 mg in 64% of cases. Overall, 604 (36%) eyes required retreatment. Of those, 79.8% were retreated with laser alone, 10.6% with anti-VEGF injection alone, and 9.6% with combined laser and injection. Complications after anti-VEGF injections occurred in 15 (0.9%) eyes, and no cases of endophthalmitis were reported. Patients in the United States had lower birth weights and gestational ages (665.6 g and 24.5 weeks, respectively) compared with non-US patients (912.7 g and 26.9 weeks, respectively) (P < 0.0001). Retreatment with reinjection and laser was significantly more common in the US compared with the non-US group (8.5% vs. 4.7% [P = 0.0016] and 55% vs. 7.2% [P < 0.001], respectively). There was no difference in the incidence of complications between the 2 geographic subgroups. CONCLUSIONS: Anti-VEGF injections for ROP were safe and well tolerated despite a variance in practice patterns. Infants with ROP receiving injections in the US tended to be younger and smaller, and they were treated earlier with more retreatments than non-US neonates with ROP.

OBJECTIVES: To test the hypothesis that ROSAH (retinal dystrophy, optic nerve oedema, splenomegaly, anhidrosis and headache) syndrome, caused by dominant mutation in ALPK1, is an autoinflammatory disease. METHODS: This cohort study systematically evaluated 27 patients with ROSAH syndrome for inflammatory features and investigated the effect of ALPK1 mutations on immune signalling. Clinical, immunologic and radiographical examinations were performed, and 10 patients were empirically initiated on anticytokine therapy and monitored. Exome sequencing was used to identify a new pathogenic variant. Cytokine profiling, transcriptomics, immunoblotting and knock-in mice were used to assess the impact of ALPK1 mutations on protein function and immune signalling. RESULTS: The majority of the cohort carried the p.Thr237Met mutation but we also identified a new ROSAH-associated mutation, p.Tyr254Cys.Nearly all patients exhibited at least one feature consistent with inflammation including recurrent fever, headaches with meningeal enhancement and premature basal ganglia/brainstem mineralisation on MRI, deforming arthritis and AA amyloidosis. However, there was significant phenotypic variation, even within families and some adults lacked functional visual deficits. While anti-TNF and anti-IL-1 therapies suppressed systemic inflammation and improved quality of life, anti-IL-6 (tocilizumab) was the only anticytokine therapy that improved intraocular inflammation (two of two patients).Patients' primary samples and in vitro assays with mutated ALPK1 constructs showed immune activation with increased NF-κB signalling, STAT1 phosphorylation and interferon gene expression signature. Knock-in mice with the Alpk1 T237M mutation exhibited subclinical inflammation.Clinical features not conventionally attributed to inflammation were also common in the cohort and included short dental roots, enamel defects and decreased salivary flow. CONCLUSION: ROSAH syndrome is an autoinflammatory disease caused by gain-of-function mutations in ALPK1 and some features of disease are amenable to immunomodulatory therapy.

Proliferative vitreoretinopathy (PVR) is a fibrotic eye disease that develops after rhegmatogenous retinal detachment surgery and open-globe traumatic injury. Idelalisib is a specific inhibitor of phosphoinositide 3-kinase (PI3K) δ. While PI3Kδ is primarily expressed in leukocytes, its expression is also considerably high in retinal pigment epithelial (RPE) cells, which play a crucial part in the PVR pathogenesis. Herein we show that GeoMx Digital Spatial Profiling uncovered strong expression of fibronectin in RPE cells within epiretinal membranes from patients with PVR, and that idelalisib (10 μM) inhibited Akt activation, fibronectin expression and collagen gel contraction induced by transforming growth factor (TGF)-β2 in human RPE cells. Furthermore, we discovered that idelalisib at a vitreal concentration of 10 μM, a non-toxic dose to the retina, prevented experimental PVR induced by intravitreally injected RPE cells in rabbits assessed by experienced ophthalmologists using an indirect ophthalmoscope plus a + 30 D fundus lens, electroretinography, optical coherence tomography and histological analysis. These data suggested idelalisib could be harnessed for preventing patients from PVR.

Purpose: To describe a case of Purtscher-like retinopathy that developed after a bowel movement. Observations: A 32-year-old male presented with blurry vision and bilateral temporal paracentral scotomas that developed immediately after standing up from a bowel movement. Fundoscopic examination was notable for bilateral cotton wool spots in the nasal macula. Optical coherence tomography showed bilateral intraretinal fluid, subfoveal fluid, and scattered areas of inner retinal hyperreflectivity and thickening corresponding to the areas of cotton wool spots on examination. No treatment was administered and the patient had significant improvement in symptoms 2 days later with resolution of macular edema. Conclusions: Here we report a case of Purtscher-like retinopathy after a bowel movement. Although the exact mechanism of Purtscher-like retinopathy is unknown, there are multiple reports of Purtscher-like retinopathy after extreme events involving Valsalva, such as during weightlifting, and we postulate that this presentation is likely of similar pathophysiology.

PURPOSE: To evaluate the retinal vasculature and vasoreactivity of patients with hypertension (HTN) using spectral domain optical coherence tomography angiography (SD-OCTA). METHODS: Patients with and without a diagnosis of HTN were included in this cross-sectional observational study. All eyes were imaged with SD-OCTA using 3 mm × 3 mm and 6 mm × 6 mm centered on both the fovea and optic disk. A second 6 mm × 6 mm scan was taken after a 30 s breath-hold. Vessel density (VD), vessel skeletonized density (VSD), and fractal dimension (FD) were calculated using customized MATLAB scripts. Vessel diameter index (VDI) was obtained by taking the ratio of VD to VSD. Vasoreactivity was measured by subtracting the VD or VSD before and after breath-hold (∆VD, ∆VSD). RESULTS: Twenty-three eyes with HTN (17 patients) and 17 control eyes (15 patients) were included. In the 6 mm × 6 mm angiogram centered on fovea, the superficial capillary plexus (SCP) VD (ß =  - 0.029, p = 0.012), VSD (ß =  - 0.004, p = 0.043) and the choriocapillaris VD (ß =  - 0.021, p = 0.030) were significantly decreased in HTN compared to control eyes. Similarly, FD was decreased in both the SCP (ß =  - 0.012, p = 0.013) and choriocapillaris (ß =  - 0.009, p = 0.030). In the 3 mm × 3 mm angiogram centered on optic disk, SCP VDI (ß =  - 0.364, p = 0.034) was decreased. ∆VD and ∆VSD were both reduced in the DCP (ß =  - 0.034, p = 0.032; ß =  - 0.013, p = 0.043) and ∆VSD was elevated in the choriocapillaris of HTN eyes (ß = 0.004, p = 0.032). CONCLUSIONS: The study used SD-OCTA to show significant differences in the retinal vasculature of hypertensive patients. It was also the first to demonstrate the potential of OCT-A to investigate retinal vascular reactivity in patients with HTN.

Purpose: To explore alterations in macular retinal thickness (RT) and analyze correlation between macular RT and pterygium area, length in pterygium patients. Methods: Totally 13 patients with pterygium (left eye) and 13 healthy controls (left eye) were recruited. OCTA was applied to scan each eye to generate three-dimensional images. Based on the Early Treatment Diabetic Retinopathy Study (ETDRS) method, each image was divided into nine subregions for the ETDRS: central (C); inner superior (IS); outer superior (OS); inner nasal (IN); outer nasal (ON); inner inferior (II); outer inferior (OI); inner temporal (IT); and outer temporal (OT). The macular RT in each subregion was measured. Furthermore, the correlation between RT and the area, length of pterygium was analyzed. Results: The visual acuity of pterygium patient was different from that of the control (P < 0.05). Besides, decreased intraretinal thickness of the IN and ON, increased intraretinal thickness of OT, decreased extraretinal thickness of OT, IN, ON, OS, and decreased retinal full layer thickness of medial superior, OS, IN, ON, and II subregions in pterygium group were observed. There was a negative correlation between RT of the IN and ON subregions and the length of pterygium (r = -0.5803 and r = -0.6013, P = 0.0376 and P = 0.0297). The RT of IN subregion was negatively correlated with pterygium area (r = -0.5844, P = 0.0359). According to the receiver operating characteristic analysis, in the ON subregion, the areas under the curve of the inner retinal thickness, outer retinal thickness and the whole retinal thickness were 1.0 (95% CI: 1.0), 0.882 (95% CI: 0.715 and 0.963), and 1.0 (95% CI: 1.0). The smallest area under the curve of retinal thickness in OT subregion was 0.018 (95% CI: 0-0.059). Conclusion: RT of pterygium patients was significantly decreased, and the main alterations occurred in the temporal side suggesting there might exist retinal structural alterations in pterygium.