Retina

Currant H, Hysi P, Fitzgerald TW, Gharahkhani P, Bonnemaijer PWM, Senabouth A, Hewitt AW, and Consortium UKBEV, and Consortium UKBEV, Atan D, Aung T, Charng J, Choquet H, Craig J, Khaw PT, Klaver CCW, Kubo M, Ong J-S, Pasquale LR, Reisman CA, Daniszewski M, Powell JE, Pébay A, Simcoe MJ, Thiadens AAHJ, van Duijn CM, Yazar S, Jorgenson E, Macgregor S, Hammond CJ, Mackey DA, Wiggs JL, Foster PJ, Patel PJ, Birney E, Khawaja AP. Genetic variation affects morphological retinal phenotypes extracted from UK Biobank optical coherence tomography images. PLoS Genet 2021;17(5):e1009497.Abstract
Optical Coherence Tomography (OCT) enables non-invasive imaging of the retina and is used to diagnose and manage ophthalmic diseases including glaucoma. We present the first large-scale genome-wide association study of inner retinal morphology using phenotypes derived from OCT images of 31,434 UK Biobank participants. We identify 46 loci associated with thickness of the retinal nerve fibre layer or ganglion cell inner plexiform layer. Only one of these loci has been associated with glaucoma, and despite its clear role as a biomarker for the disease, Mendelian randomisation does not support inner retinal thickness being on the same genetic causal pathway as glaucoma. We extracted overall retinal thickness at the fovea, representative of foveal hypoplasia, with which three of the 46 SNPs were associated. We additionally associate these three loci with visual acuity. In contrast to the Mendelian causes of severe foveal hypoplasia, our results suggest a spectrum of foveal hypoplasia, in part genetically determined, with consequences on visual function.
Ng CC, Brill D, Cunningham ET, Burckhard BA, Jumper MJ, Heier J, Rifkin LM, Eliott D, McDonald RH, Sobrin L. Catastrophic, Bilateral Retinal Vascular Occlusion after Intravitreal Bevacizumab Injection. Retin Cases Brief Rep 2021;Abstract
PURPOSE: To describe two cases of catastrophic, bilateral retinal vascular occlusion following intravitreal (IVT) bevacizumab injection. METHODS: Case series. Main outcome measures included clinical and fluorescein angiography (FA) findings. RESULTS: Case 1 - A 65-year-old woman with calcinosis, Raynaud's phenomenon, esophageal dysfunction, sclerodactyly, and telangiectasis (CREST) syndrome developed acute, severe, bilateral visual loss two weeks following bilateral IVT bevacizumab injection for proliferative diabetic retinopathy. Examination and FA revealed moderate anterior chamber inflammation, bilateral perivascular retinal hemorrhages and near total retinal vascular occlusion. Extensive testing revealed moderately elevated anti-B2 glycoprotein (antiphospholipid) antibodies. Case 2 - An 85-year-old man with polymyalgia rheumatica and left eye exudative age-related macular degeneration experienced severe, bilateral, sequential visual loss in the left then right eye approximately three weeks following IVT bevacizumab left eye injection. Examination revealed bilateral panuveitis, diffuse perivascular exudates, and intraretinal hemorrhages. FA showed diffuse venous leakage. Extensive testing revealed an elevated anti-nuclear antibody and mildly elevated anti-cardiolipin antibody. CONCLUSION: Patients with underlying retinal vascular vulnerabilities may be at increased risk of catastrophic, bilateral retinal vascular occlusion following treatment with IVT bevacizumab. The moderate to severe intraocular inflammation in both cases, and the contralateral involvement following unilateral IVT injection in Case 2, suggest a possible delayed immune-mediated mechanism.
Ma J, Chen M, Ai J, Young MJ, Ge J. Enhanced migration of engrafted retinal progenitor cells into the host retina via disruption of glial barriers. Mol Vis 2021;27:300-308.Abstract
Purpose: Migration and integration remain critical challenges for stem cell replacement therapy. Glial barriers play an important role in preventing cell migration and integration. The purpose of this study was to investigate the effect and mechanisms of chondroitinase ABC on the migration of murine retinal progenitor cells (mRPCs) transplanted into the subretinal space of B6 mice. Methods: mRPCs were harvested from the neural retinas of P1 enhanced green fluorescent protein (GFP) B6 mice. Two μl containing 2 × 105 expanded RPCs alone or combined with chondroitinase ABC in suspension were injected into the subretinal space of the recipient B6 mice. Immunohistochemistry was performed on the recipient B6 retinas to evaluate the glial barrier formation and migration of the mRPCs. Western blotting was also used to check the expression of the glial barriers. Results: Glial fibrillary acidic protein (GFAP) and vimentin could be seen around the transplanted mRPCs in the B6 mice. Formation of glial barriers prevented the migration of donor cells into the retinal layers. Chondroitinase ABC promoted the migration and survival rates of the engrafted retinal progenitor cells in the retinal layers of recipient B6 mice. Injection induced upregulation of GFAP, chondroitin, and CD44 expression. Chondroitinase ABC disrupted the glial barriers. The CD44 around the mRPCs was much lower in the chondroitinase group. However, the CD44 in the retinal layers was considerably higher in the chondroitinase group. With the employment of chondroitinase ABC, more cells migrated into the outer nuclear layer or inner nuclear layer. The chondroitin and CD44 expression decreased 3 weeks after transplantation in the chondroitinase ABC group. Conclusions: Chondroitinase ABC degraded glial barriers and enhanced the migration of transplanted mouse retinal progenitor cells. Chondroitinase ABC may also have induced activation of the CD44 signaling pathway to exert the effect.
Xue Y, Wang SK, Rana P, West ER, Hong CM, Feng H, Wu DM, Cepko CL. AAV-Txnip prolongs cone survival and vision in mouse models of retinitis pigmentosa. Elife 2021;10Abstract
Retinitis pigmentosa (RP) is an inherited retinal disease affecting >20 million people worldwide. Loss of daylight vision typically occurs due to the dysfunction/loss of cone photoreceptors, the cell type that initiates our color and high-acuity vision. Currently, there is no effective treatment for RP, other than gene therapy for a limited number of specific disease genes. To develop a disease gene-agnostic therapy, we screened 20 genes for their ability to prolong cone photoreceptor survival in vivo. Here, we report an adeno-associated virus vector expressing Txnip, which prolongs the survival of cone photoreceptors and improves visual acuity in RP mouse models. A allele, C247S, which blocks the association of Txnip with thioredoxin, provides an even greater benefit. Additionally, the rescue effect of Txnip depends on lactate dehydrogenase b (Ldhb) and correlates with the presence of healthier mitochondria, suggesting that Txnip saves RP cones by enhancing their lactate catabolism.
Lonfat N, Wang S, Lee C, Garcia M, Choi J, Park PJ, Cepko C. Cis-regulatory dissection of cone development reveals a broad role for Otx2 and Oc transcription factors. Development 2021;148(9)Abstract
The vertebrate retina is generated by retinal progenitor cells (RPCs), which produce >100 cell types. Although some RPCs produce many cell types, other RPCs produce restricted types of daughter cells, such as a cone photoreceptor and a horizontal cell (HC). We used genome-wide assays of chromatin structure to compare the profiles of a restricted cone/HC RPC and those of other RPCs in chicks. These data nominated regions of regulatory activity, which were tested in tissue, leading to the identification of many cis-regulatory modules (CRMs) active in cone/HC RPCs and developing cones. Two transcription factors, Otx2 and Oc1, were found to bind to many of these CRMs, including those near genes important for cone development and function, and their binding sites were required for activity. We also found that Otx2 has a predicted autoregulatory CRM. These results suggest that Otx2, Oc1 and possibly other Onecut proteins have a broad role in coordinating cone development and function. The many newly discovered CRMs for cones are potentially useful reagents for gene therapy of cone diseases.
Hanumunthadu D, Lescrauwaet B, Jaffe M, Sadda SV, Wiecek E, Hubschman JP, Patel PJ. Clinical Update on Metamorphopsia: Epidemiology, Diagnosis and Imaging. Curr Eye Res 2021;46(12):1777-1791.Abstract
Purpose: To discuss the pathophysiology of metamorphopsia, its characterisation using retinal imaging and methods of assessment of patient symptoms and visual function.Methods: A literature search of electronic databases was performedResults: Metamorphopsia has commonly been associated with vitreomacular interface disorders (such as epiretinal membrane) and has also regularly been noted in diseases of the retina and choroid, particularly age-related macular degeneration and central serous chorioretinopathy. Developments in optical coherence tomography retinal imaging have enabled improved imaging of the foveal microstructure and have led to the localisation of the pathophysiology of metamorphopsia within the retinal layers of the macula. Alteration of alignment of inner and outer retinal layers at various retinal loci has been identified using multimodal imaging in patients with metamorphopsia in a range of conditions. Although the Amsler Grid assessment of metamorphopsia is a useful clinical indicator, new emerging methods of metamorphopsia assessment with psychophysical tests such as M-CHARTS and preferential hyperacuity perimetry, have been developed.Conclusions: It appears that there is a complex relationship between visual acuity and metamorphopsia symptoms that vary between retinal conditions. Although metamorphopsia has traditionally been challenging to measure in the clinic, advances in technology promise more robust, easy-to-use tests. It is possible that home assessment of metamorphopsia, particularly in conditions such as age-related macular degeneration, may help to guide the need for further clinic evaluation and consideration of treatment.
Deitch I, Ferenchak K, Miller JB. Quantitative autofluorescence: Review of Current Technical Aspects and Applications in Chorioretinal Disease. Semin Ophthalmol 2021;36(4):346-350.Abstract
Purpose: In this review we discuss the broad clinical application of qAF and provide a descriptive summary of the phenotypic findings of different chorioretinal pathologies.Background: Quantitative Fundus autofluorescence (qAF) is a novel developing technology that can aid in diagnosis and longitudinal disease monitoring by measuring and comparing autofluorescence intensities. Fundus autofluorescence (FAF) is a noninvasive imaging method that creates a density map of the fluorophores of the ocular fundus and provides both functional and topographic anatomic information about retinal cells. Fluorophores are molecules that have the ability to temporarily absorb irradiated light, and emit a small amount of light of a different wavelength. Different endogenous fluorophores can be found in the ocular fundus. Changes in accumulation of retinal fluorophores usually indicate retinal pathology and create characteristic patterns of hyper-autofluorescence and hypo-autofluorescence that help establish a diagnosis.Conclusion: qAF allows a safe non-invasive visualization of the retina, enables a standard for AF intensities comparison and aids to the understanding of the genotype-phenotype correlations.
Gjerde H, Mantagos IS. Charting the Globe: How Technologies Have Affected Our Understanding of Retinal Findings in Abusive Head Trauma/Shaken Baby Syndrome. Semin Ophthalmol 2021;36(4):205-209.Abstract
Purpose: Ocular findings such as retinal hemorrhages are common in abusive head trauma (AHT). Binocular indirect ophthalmoscopy has been the standard for assessing the eyes of children who are victims of AHT. However, technological advances have changed our understanding of retinal findings in AHT.Methods: Literature review on AHT - retinal findings, imaging technologies, models of representation, and telemedicine applications.Results: Many studies suggest vitreoretinal traction from repetitive acceleration-deceleration shearing forces during shaking plays an important role in the development of retinal findings in AHT. This is further supported by different imaging modalities [optical coherence tomography (OCT); magnetic resonance imaging (MRI); fluorescein angiography (FA)] and models of representation (animal and mechanical models; finite element analysis).Conclusion: Emerging technologies have augmented our diagnostic abilities, enhanced our understanding regarding the pathophysiology of retinal findings, and strengthened the link between vitreoretinal traction and ocular pathology in AHT. Telemedicine is also starting to play an important role in AHT.
Breazzano MP, Nair AA, Arevalo FJ, Barakat MR, Berrocal AM, Chang JS, Chen A, Eliott D, Garg SJ, Ghadiali Q, Gong D, Grewal DS, Handa JT, Henderson M, Leiderman YI, Leng T, Mannina A, Mendel TA, Mustafi D, de Koo LOC, Patel SN, Patel TP, Prenner J, Richards P, Singh RP, Wykoff CC, Yannuzzi NA, Yu H, Modi YS, Chang S. Frequency of Urgent or Emergent Vitreoretinal Surgical Procedures in the United States During the COVID-19 Pandemic. JAMA Ophthalmol 2021;139(4):456-463.Abstract
Importance: The American Academy of Ophthalmology (AAO) indicated that urgent or emergent vitreoretinal surgical procedures should continue during the coronavirus disease 2019 (COVID-19) pandemic. Although decreases in the frequency of critical procedures have been reported outside the field of ophthalmology, analyses are limited by volume, geography, and time. Objective: To evaluate whether the frequency of ophthalmic surgical procedures deemed urgent or emergent by the AAO changed across the United States during the COVID-19 pandemic. Design, Setting, and Participants: Vitreoretinal practices from 17 institutions throughout the US participated in this multicenter cross-sectional study. The frequency of 11 billed vitreoretinal Current Procedural Terminology (CPT) codes across respective weeks was obtained from each practice between January 1, 2019, and May 31, 2020. Data were clustered into intravitreal injections (code 67028), lasers and cryotherapy (codes 67141, 67145, and 67228), retinal detachment (RD) repairs (codes 67107, 67108, 67110, and 67113), and other vitrectomies (codes 67036, 67039, and 67040). Institutions were categorized by region (Northeast, Midwest, South, and West Coast), practice setting (academic [tax-exempt] or private [non-tax-exempt]), and date of respective statewide stay-at-home orders. Main Outcomes and Measures: Nationwide changes in the frequency of billing for urgent or emergent vitreoretinal surgical procedures during the COVID-19 pandemic. Results: A total of 526 536 CPT codes were ascertained: 483 313 injections, 19 257 lasers or cryotherapy, 14 949 RD repairs, and 9017 other vitrectomies. Relative to 2019, a weekly institutional decrease in injections was observed from March 30 to May 2, 2020, with a maximal 38.6% decrease (from a mean [SD] of 437.8 [436.3] to 273.8 [269.0] injections) from April 6 to 12, 2020 (95% CI, -259 to -69 injections; P = .002). A weekly decrease was also identified that spanned a longer interval, at least until study conclusion (March 16 to May 31, 2020), for lasers and cryotherapy, with a maximal 79.6% decrease (from a mean [SD] of 6.6 [7.7] to 1.5 [2.0] procedures) from April 6 to 12, 2020 (95% CI, -6.8 to -3.3 procedures; P < .001), for RD repairs, with a maximal 59.4% decrease (from a mean [SD] of 3.5 [4.0] to 1.6 [2.2] repairs) from April 13 to 19, 2020 (95% CI, -2.7 to -1.4 repairs; P < .001), and for other vitrectomies, with a maximal 84.3% decrease (from a mean [SD] of 3.0 [3.1] to 0.4 [0.8] other vitrectomies) from April 6 to 12, 2020 (95% CI, -3.3 to -1.8 other vitrectomies; P < .001). No differences were identified by region, setting, or state-level stay-at-home order adjustment. Conclusions and Relevance: Although the AAO endorsed the continued performance of urgent or emergent vitreoretinal surgical procedures, the frequency of such procedures throughout the country experienced a substantial decrease that may persist after the COVID-19 pandemic's initial exponential growth phase. This decrease appears independent of region, setting, and state-level stay-at-home orders. It is unknown to what extent vitreoretinal intervention would have decreased without AAO recommendations, and how the decrease is associated with outcomes. Although safety is paramount during the COVID-19 pandemic, practices should consider prioritizing availability for managing high-acuity conditions until underlying reasons for the reduction are fully appreciated.
Georgiou M, Fujinami K, Vincent A, Nasser F, Khateb S, Vargas ME, Thiadens AAHJ, de Carvalho ER, Nguyen X-T-A, Cabral De Guimarães TA, Robson AG, Mahroo OA, Pontikos N, Arno G, Fujinami-Yokokawa Y, Leo SM, Liu X, Tsunoda K, Hayashi T, Jimenez-Rolando B, Martin-Merida MI, Avila-Fernandez A, Carreño E, Garcia-Sandoval B, Carmen A, Sharon D, Kohl S, Huckfeldt RM, Boon CJF, Banin E, Pennesi ME, Wissinger B, Webster AR, Héon E, Khan AO, Zrenner E, Michaelides M. KCNV2-associated Retinopathy: Detailed Retinal Phenotype and Structural Endpoints - KCNV2 Study Group Report 2. Am J Ophthalmol 2021;Abstract
PURPOSE: To describe the detailed retinal phenotype of KCNV2-associated retinopathy. STUDY DESIGN: Multicenter international retrospective case series. METHODS: Review of retinal imaging including fundus autofluorescence (FAF) and optical coherence tomography (OCT), including qualitative and quantitative analyses. RESULTS: Three distinct macular FAF features were identified: i) centrally increased signal (n=35, 41.7%), ii) DAF (n=27, 31.1%), and iii) ring of increased signal (n=37, 44.0%). Five distinct FAF groups were identified based on combinations of those characteristics, with 23.5% of patients changing FAF group over a mean (range) follow-up of 5.9 years (1.9-13.1 years). Qualitative assessment was performed by grading OCT into five grades: (i) continuous EZ (20.5%), (ii) EZ disruption (26.1%), (iii) EZ absence, without optical gap and with preserved retinal pigment epithelium (RPE) complex (21.6%); iv) loss of EZ and an hyporeflective zone at the foveola (6.8%); and (v) outer retina and RPE complex loss (25.0%). Eighty-six patients had scans available from both eyes, with 83 (96.5%) having the same grade in both eyes, and 36.1% changed OCT grade over a mean follow-up of 5.5 years. The annual rate of ONL thickness change was similar for right and left eyes. CONCLUSION: KCNV2-associated retinopathy is a slowly progressive disease with early retinal changes, which are predominantly symmetric between eyes. The identification of a single OCT or FAF measurement as an endpoint to determine progression that applies to all patients may be challenging; although ONL thickness is a potential biomarker. Findings suggest a potential window for intervention until 40 years of age.
Navaratnam J, Salvanos P, Vavvas DG, Bragadóttir R. Ultra-widefield autofluorescence imaging findings in retinoschisis, rhegmatogenous retinal detachment and combined retinoschisis retinal detachment. Acta Ophthalmol 2021;99(2):195-200.Abstract
PURPOSE: Retinoschisis (RS), rhegmatogenous retinal detachment (RRD) and combined RS retinal detachment (RSRD) may resemble clinically and pose a diagnostic challenge. This study investigates the role of the fundus autofluorescence (AF) in differentiating RS, RRD and RSRD. METHODS: Fundus AF changes of 34 eyes diagnosed with RRD, 30 eyes with RS and 12 eyes with RSRD were retrospectively analysed. Ultra-widefield AF (UW-AF) image intensities obtained with the Optomap 200Tx were interpreted as hypo-, hyper- and isoautofluorescent or a mixed pattern with hypo- and hyperautofluorescence over and at the posterior margin (PM) of RRD, RS and RSRD. RESULTS: All RS eyes revealed isoautofluorescence over the area of RS, and nine eyes (30%) showed hypoautofluorescent PM. Among RRD, acute (≤2 weeks) and chronic (>2 weeks) RRD demonstrated distinct AF characteristics. Sixty-two per cent of RRD eyes had acute RRD. From those, 16 eyes (76%) demonstrated hypoautofluorescence over the detached area and 19 (90%) eyes with hyperautofluorescent PM. Sixty-two per cent of chronic RRD eyes demonstrated isoautofluorecence over the detached area. Eight RSRD eyes (67%) revealed hyperautofluorescence in the detached area. The positive predictive value (PPV) for hypoautofluorescence over the area of subretinal fluid (SRF) in RRD was 95%. The PPV for hyperautofluorescence over the area of SRF in RSRD was 100% and for isoautofluorescence for schitic area in RSRD and RS was 76%. CONCLUSION: The UW-AF can be a useful non-invasive adjuvant tool to distinguish between RRD, RS and RSRD. Hypo- or hyperautofluorescence over the area of interest and hyperautofluorescent PM indicates the presence of SRF.
Dahrouj M, Miller JB. Artificial Intelligence (AI) and Retinal Optical Coherence Tomography (OCT). Semin Ophthalmol 2021;36(4):341-345.Abstract
Ophthalmology has been at the forefront of medical specialties adopting artificial intelligence. This is primarily due to the "image-centric" nature of the field. Thanks to the abundance of patients' OCT scans, analysis of OCT imaging has greatly benefited from artificial intelligence to expand patient screening and facilitate clinical decision-making.In this review, we define the concepts of artificial intelligence, machine learning, and deep learning and how different artificial intelligence algorithms have been applied in OCT image analysis for disease screening, diagnosis, management, and prognosis.Finally, we address some of the challenges and limitations that might affect the incorporation of artificial intelligence in ophthalmology. These limitations mainly revolve around the quality and accuracy of datasets used in the algorithms and their generalizability, false negatives, and the cultural challenges around the adoption of the technology.
Wu F, Goldenberg PC, Mukai S. Bilateral anterior segment dysgenesis and peripheral avascular retina with tractional retinal detachment in an infant with multiple congenital anomalies-hypotony-seizures syndrome 3. Ophthalmic Genet 2021;42(3):334-337.Abstract
Background: Multiple congenital anomalies-hypotony-seizures syndrome 3 (MCAHS3) is a rare autosomal recessive disorder caused by mutations in the PIGT gene. PIGT encodes phosphatidylinositol-glycan biosynthesis class T, which plays a crucial role in protein anchoring to cell membranes. The clinical presentation of MCAHS3 is variable in expression and severity, but can be characterized by developmental delay, seizures, hypotonia, facial dysmorphism, and other abnormalities.Materials and Methods: Case report.Results: We report unusual ocular findings including bilateral anterior segment dysgenesis, avascular retinal periphery, and tractional retinal detachment in a 1-month-old male infant with compound heterozygous PIGT mutations consistent with MCAHS3. Whole-exome sequencing did not detect any other genetic abnormalities.Conclusions: This case expands the clinical spectrum of MCAHS3 to include anomalies in ocular anterior segment and retinal vascular development. Given the rarity and the genetic heterogeneity of MCAHS3, giving rise to varied non-ocular phenotypes, it is possible that milder intraocular phenotypes could have gone unrecognized in the past.

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