Exploring the diverse clinical and variant spectrum of CEP78-associated syndrome: Novel pathogenic variants identified in a case series.

Dual sensory impairment, commonly referred to as combined hearing and vision loss, can stem from a diverse spectrum of conditions, each presenting with its unique set of clinical characteristics. Our understanding of dual sensory impairment has expanded significantly in the past decade, broadening the scope of genetic differential diagnoses, including genes such as CEP250, ARSG, TUBB4B, CEP78, and ABHD12. A case series including three patients from two families with genetically diagnosed CEP78-associated cone-rod dystrophy was identified. We collected and reviewed their clinical records, imaging data, and genetic testing results. In addition, a comprehensive literature review was conducted on the phenotype and the genetic testing modality employed in all published CEP78 cases through a PubMed search using the keyword "CEP78." A retinal dystrophy panel detected a novel homozygous CEP78 pathogenic variant (c.1447C>T, p.Arg483*) in siblings-Cases 1 and 2-from Family 1. Both teenagers have a clinical diagnosis of cone-rod dystrophy with presumed normal hearing. Case 3 from Family 2, diagnosed with cone-rod dystrophy and early-onset hearing loss, was found to carry a CEP78 pathogenic variant (c.1206-2A>C) and a likely pathogenic variant (c.856_857del, p.Leu286Glyfs*12) also through panel-based genetic testing. Intriguingly, neither of these variants was reported in an affected sibling's clinical whole-exome sequencing (WES) report when performed in 2015. A review of CEP78-related literature unveiled that the initial report linking CEP78 to cone-rod dystrophy and hearing loss was published in September 2016. Any pathogenic variant found in CEP78 before 2016 would have been categorized as a "clearly disruptive variant in a gene of uncertain significance (GUS)" and might not have been reported in the WES report. It is important to acknowledge that our understanding of genotype-phenotype associations is undergoing rapid expansion. It is also crucial to recognize that repeat genetic testing may represent a fundamentally different approach, given the technological advancements not only in the coverage of the sequencing but also in the more comprehensive understanding of genotype-phenotype associations. This case series also enriches the existing CEP78 literature by providing phenotypic details of the youngest case of CEP78-associated retinopathy reported in the literature (Case 2), which expands our perspective on the natural history of disease in this disorder.

Vitamin A deficiency retinopathy in the setting of celiac disease and liver fibrosis.

PURPOSE: Vitamin A is a lipid-soluble compound that is critical in maintaining phototransduction. Ocular manifestations of hypovitaminosis A may present with anterior segment signs of xeropthalmia, with advanced cases also causing classic retinal and electrophysiologic changes of vitamin A deficiency retinopathy. We present a case of vitamin A deficiency retinopathy, with corresponding retinal imaging and electrophysiology, in an adult patient with celiac disease and liver fibrosis. METHODS: A single case report was conducted in Toronto, Canada. RESULTS: A 77-year-old male with known celiac disease and liver fibrosis presented progressively worsening vision noticed primarily when driving. Vision was 20/50 OD and 20/200 OS. Bitot spots were noted on anterior segment examination. Fundus photography demonstrated bilateral peripheral macular hypopigmentation and far-peripheral granular retinal hypopigmentation with focal yellow dots and hyper-pigmented deposits. Optical coherence tomography (OCT) imaging demonstrated indistinct outer retinal banding with mild outer nuclear layer thinning, focal hyper-reflective deposits, and a thin choroid bilaterally. Full-field electroretinography (ERG) testing demonstrated reduced rod-isolated and combined rod-cone response amplitudes, and multifocal ERG testing demonstrated blunted individual responses throughout the field. The patient was treated with pulse vitamin A therapy. After 6 months of therapy, ERG responses were back within reference range, and the outer retinal changes reversed; visual acuity improved to 20/30 OD and 20/40 OS. CONCLUSION: This case represents the classic findings of vitamin A deficiency retinopathy on fundus examination and electrophysiologic testing secondary to gastrointestinal pathology. Prompt treatment of high dose vitamin A supplementation led to improvement of full-field and multifocal ERG results, as well as reconstitution of outer retinal architecture.

PREDICTIVE FACTORS OF SPONTANEOUS RELEASE OF VITREOMACULAR TRACTION: A Systematic Review and Meta-Analysis.

PURPOSE: To review predictive factors of spontaneous vitreomacular traction (VMT) release. METHODS: A systematic literature search was performed on Ovid MEDLINE, Embase, and Cochrane Library. Studies comparing spontaneously released VMT to persistent VMT were included. A meta-analysis was performed using a random effects model, and weighted mean difference, risk ratio (RR), and 95% confidence intervals (95% CI) were reported as appropriate. RESULTS: Of a search of 258 studies, 12 studies were included, from which 272 of 934 eyes (29%) underwent spontaneous release. Mean age was 70.0 years, 37.2% of patients were men, and mean follow-up was 22.0 months. Significant predictive factors for spontaneous release were smaller VMT diameter (n = 177; weighted mean difference = -212.48 µm, 95% CI = [-417.36, -7.60], P = 0.04), epiretinal membrane absence (n = 162; RR = 2.17, 95% CI = [1.18, 3.97], P = 0.01), and right eye involvement (n = 76; RR = 2.10, 95% CI = [1.14, 3.88], P = 0.02). Nonsignificant factors were age, initial best-corrected visual acuity, sex, ocular comorbidity, fellow-eye posterior vitreous detachment, previous intravitreal injection, and VMT classification with focal defined as ≤400 µm. Mean release time was 15.3 months (n = 212). Mean best-corrected visual acuity improved from 0.34 ± 0.21 (Snellen 20/44) to 0.20 ± 0.58 logMAR (Snellen 20/32) postrelease (n = 121). CONCLUSION: Smaller VMT diameter, epiretinal membrane absence, and right eye involvement may support spontaneous VMT release. If patients have tolerable symptoms, clinicians may consider observation in patients with these predictive factors.

The Next Generation of Molecular and Cellular Therapeutics for Inherited Retinal Disease.

Inherited retinal degenerations (IRDs) are a diverse group of conditions that are often characterized by the loss of photoreceptors and blindness. Recent innovations in molecular biology and genomics have allowed us to identify the causative defects behind these dystrophies and to design therapeutics that target specific mechanisms of retinal disease. Recently, the FDA approved the first in vivo gene therapy for one of these hereditary blinding conditions. Current clinical trials are exploring new therapies that could provide treatment for a growing number of retinal dystrophies. While the field has had early success with gene augmentation strategies for treating retinal disease based on loss-of-function mutations, many novel approaches hold the promise of offering therapies that span the full spectrum of causative mutations and mechanisms. Here, we provide a comprehensive review of the approaches currently in development including a discussion of retinal neuroprotection, gene therapies (gene augmentation, gene editing, RNA modification, optogenetics), and regenerative stem or precursor cell-based therapies. Our review focuses on technologies that are being developed for clinical translation or are in active clinical trials and discusses the advantages and limitations for each approach.

Wide-field true-colour imaging and clinical characterization of a novel GRK1 mutation in Oguchi disease.

PURPOSE: The available literature regarding Oguchi disease is limited, with around 50 cases described to date. Caused by mutations to either the SAG gene coding for arrestin (Hayashi et al. in Ophthalmic Res 46:175-180, 2011) or the GRK1 gene coding for rhodopsin kinase (Yamamoto et al. in Nat Genet 15:175-178. https://doi.org/10.1038/ng0297-175 , 1997), Oguchi disease is an autosomal recessive condition with a good visual prognosis. The clinical diagnosis of the condition is based on the presence of night blindness (nyctalopia), as well as fundoscopic observation of the Mizuo-Nakamura phenomenon. The Mizuo-Nakamura phenomenon refers to a fundus discolouration described as a golden-brown colour with a yellow-grey metallic sheen most prominent in the peripheral retina; after prolonged dark adaptation, the fundus appears normal. The prevalence of Oguchi disease is highest in Japan, particularly with SAG mutations (Nakazawa et al. in Retina 17:17-22, 1997), although patients from Europe, Pakistan and India have also been described. Formal diagnosis requires genetic testing. METHODS: Wide-field fundus images were obtained in both dark-adapted and light-adapted retina. Optical coherence tomography and dark-adapted electroretinography responses were used to further characterize the clinical phenotype. RESULTS: Existing descriptions of Oguchi disease have been limited by available technology. The flashes required for 45°-montage photographs in a dark-adapted eye quickly cause light adaptation. Recent advances in technology enable the capture of larger retinal areas in a single image. Wide-field 133° images were obtained of the native and dark-adapted fundus in natural colour. To our knowledge, these represent the first reported single-wide-field images of Oguchi disease, showing the characteristic Mizuo-Nakamura phenomenon in true colour. Genetic testing revealed a novel homozygous mutation in GRK1. CONCLUSIONS: Here, we demonstrate how characterizing this condition with single-shot true-colour wide-field imaging has distinct advantages over scanning laser technology, which applies artificial colouration, or stitched true-colour images. Images captured with wide-field systems create a much better representation of the native and dark-adapted fundus than can be observed by the ophthalmologist using direct fundoscopy and are essential in the clinical characterization of new mutations.

Induction of Rod and Cone Photoreceptor-Specific Progenitors from Stem Cells.

Retinal degeneration includes a variety of diseases for which there is no regenerative therapy. Cellular transplantation is one potential approach for future therapy for retinal degeneration, and stem cells have emerged as a promising source for future cell therapeutics. One major barrier to therapy is the ability to specify individual photoreceptor lineages from a variety of stem cell sources. In this review, we focus on photoreceptor genesis from progenitor populations in the developing embryo and how this understanding has given us the tools to manipulate cultures to specific unique rod and cone lineages from adult stem cell populations. We discuss experiments and evidence uncovering the lineage mechanisms at play in the establishment of fate-specific rod and cone photoreceptor progenitors. This may lead to an improved understanding of retinal development in vivo, as well as new cell sources for transplantation.

Challenges facing physician scientist trainees: a survey of trainees in Canada's largest undergraduate and postgraduate programs in a single centre.

PURPOSE: A number of indicators suggest that the physician scientist career track is threatened. As such, it is an opportune time to evaluate current training models. Perspectives on physician scientist education and career path were surveyed in trainees at the University of Toronto, home to Canada's longest standing physician scientist training programs. METHODS: Trainees from the Clinician Investigator Program (CIP) and MD/PhD Program at the University of Toronto were surveyed. Liekert-style closed-ended questions were used to assess future career goals, present and future perspectives and concerns about and beliefs on training. Demographic information was collected regarding year of study, graduate degree program and focus of clinical and health research. Statistical analysis included non-parametric tests for sub-group comparisons. RESULTS: Both groups of trainees were motivated to pursue a career as a physician scientist. While confident in their decision to begin and complete physician scientist training, they expressed concerns about the level of integration between clinical and research training in the current programs. They also expressed concerns about career outlook, including the ability to find stable and sustainable careers in academic medicine. Trainees highlighted a number of factors, including career mentorship, as essential for career success. CONCLUSION: These findings indicate that while trainees at different stages consistently express career motivation, they identified concerns that are program- and training stage-specific. These concerns mirror those highlighted in the medical education literature regarding threats to the physician scientist career path. Understanding these different and changing perspectives and exploring those differences could form an important basis for trainee program improvements both nationally and internationally.

SEVERE MACULAR EDEMA AFTER TRAUMATIC HEAD INJURY: A CASE OF WHIPLASH MACULOPATHY.

PURPOSE: Whiplash or "traumatic" maculopathy is associated with retinal concussion, typically after the rapid acceleration/deceleration experienced in motor vehicle collisions. It has rarely been discussed in the literature, likely given the spontaneous and relatively rapid nature with which the acute macular edema resolves. A focused clinical history around the trauma and characteristic signs and structural features on retinal imaging help to distinguish this condition from other sequelae of concussive retinal injury. We report a case of whiplash maculopathy after a blunt injury to the head, which presented with unilateral and substantial macular edema in the left eye. METHODS: Case report. RESULTS: A 38-year-old man presented with complaint of a central scotoma in his left eye after a blunt trauma to his head. Comprehensive ophthalmological evaluation and retinal imaging with optical coherence tomography confirmed whiplash maculopathy, with acute macular edema in his left eye. Management with observation and close follow-up showed rapid improvement in his visual symptoms over the course of days and improvement in the severity of macular edema. One month after his injury, macular edema had resolved with only mild structural irregularities, the patient's vision had improved, and he was asymptomatic. CONCLUSION: When observing patients with significant macular edema after concussive head injury, whiplash maculopathy should be considered, regardless of a history of motor vehicle collision. The condition can present with significant asymmetry of disease. The diagnosis generally carries a good prognosis for vision; however, there are cases of persistent central visual disturbances.

Inherited Retinal Diseases and Retinal Organoids as Preclinical Cell Models for Inherited Retinal Disease Research.

Inherited retinal diseases (IRDs) are a large group of genetically and clinically diverse blinding eye conditions that result in progressive and irreversible photoreceptor degeneration and vision loss. To date, no cures have been found, although strides toward treatments for specific IRDs have been made in recent years. To accelerate treatment discovery, retinal organoids provide an ideal human IRD model. This review aims to give background on the development and importance of retinal organoids for the human-based in vitro study of the retina and human retinogenesis and retinal pathologies. From there, we explore retinal pathologies in the context of IRDs and the current landscape of IRD treatment discovery. We discuss the usefulness of retinal organoids in this context (as a patient-derived cell model for IRDs) to precisely understand the pathogenesis and potential mechanisms behind a specific IRD-causing variant of interest. Finally, we discuss the importance and promise of retinal organoids in treatment discovery for IRDs, now and in the future.

Streamlined Ophthalmologist-Led Pathway to Diagnosis and Accessibility of Genetics Testing for Patients with Inherited Retinal Dystrophies in Canada.

OBJECTIVE: To investigate the ability of a new clinical model to improve accessibility and expedite the pathway to molecular diagnosis for patients with suspected inherited retinal diseases (IRDs). DESIGN: Retrospective cohort study of electronic patient records. PARTICIPANTS: All patients referred to general medical genetic clinic between September 2017 and September 2019 and an ophthalmologist-led IRD clinic between October 2021 and July 2023 for suspected IRD were included. METHODS: The difference in timeliness and accessibility to diagnosis and genetics testing for patients referred for suspected IRDs were compared based on whether they were referred to a general medical genetics clinic or an ophthalmologist-led IRD clinic. MAIN OUTCOME MEASURES: The primary outcomes were time to consult from referral; time from initial consult to molecular diagnosis; and the time from initial consult to genetics result disclosure and counseling. Secondary outcomes included number of prior providers investigating the chief complaint, the proportion of patients undergoing genetics testing, and the range of diagnostic investigations undertaken. RESULTS: Four hundred seventy-three patients were included, with 212 cases from a general medical genetics clinic and 261 from a medical retina clinic. The mean time from referral to initial consult was 14 months (±3.33 months) and 4 months (±3.4 months) for the general medical genetics and the ophthalmologist-led IRD clinics, respectively. The mean time from initial consult to genetics disclosure and counseling was 6 months (±3.6 months) and 3.5 months (±1.8 months) for the medical genetics and the ophthalmologist-led models, respectively. The total time from initial referral to genetics disclosure and counseling for the medical geneticist-led clinic model was 20 to 24 months. The total time from initial referral to genetics disclosure and counseling for the ophthalmologist-led retinal clinic was 5 to 8 months. The average number of prior providers seen before presenting to the ophthalmologist-led retina clinic was 2.05 (range, 1-10). CONCLUSIONS: Shifting from the traditional medical genetics model to the new ophthalmologist-led IRD clinical model may improve accessibility and expedite the pathway to molecular diagnosis and subsequent gene therapy trials for patients with suspected IRDs. FINANCIAL DISCLOSURE(S): Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Ensemble of deep convolutional neural networks is more accurate and reliable than board-certified ophthalmologists at detecting multiple diseases in retinal fundus photographs.

AIMS: To develop an algorithm to classify multiple retinal pathologies accurately and reliably from fundus photographs and to validate its performance against human experts. METHODS: We trained a deep convolutional ensemble (DCE), an ensemble of five convolutional neural networks (CNNs), to classify retinal fundus photographs into diabetic retinopathy (DR), glaucoma, age-related macular degeneration (AMD) and normal eyes. The CNN architecture was based on the InceptionV3 model, and initial weights were pretrained on the ImageNet dataset. We used 43 055 fundus images from 12 public datasets. Five trained ensembles were then tested on an 'unseen' set of 100 images. Seven board-certified ophthalmologists were asked to classify these test images. RESULTS: Board-certified ophthalmologists achieved a mean accuracy of 72.7% over all classes, while the DCE achieved a mean accuracy of 79.2% (p=0.03). The DCE had a statistically significant higher mean F1-score for DR classification compared with the ophthalmologists (76.8% vs 57.5%; p=0.01) and greater but statistically non-significant mean F1-scores for glaucoma (83.9% vs 75.7%; p=0.10), AMD (85.9% vs 85.2%; p=0.69) and normal eyes (73.0% vs 70.5%; p=0.39). The DCE had a greater mean agreement between accuracy and confident of 81.6% vs 70.3% (p<0.001). DISCUSSION: We developed a deep learning model and found that it could more accurately and reliably classify four categories of fundus images compared with board-certified ophthalmologists. This work provides proof-of-principle that an algorithm is capable of accurate and reliable recognition of multiple retinal diseases using only fundus photographs.

Full-Thickness Macular Hole Due to Choroidal Neovascularization in the Setting of Pathologic Myopia.

Purpose: To present a case of myopic choroidal neovascularization (CNV) leading to a full-thickness macular hole (MH) in a patient with macular schisis. Methods: A single case was evaluated. Results: A 65-year-old woman presented with myopic staphyloma and foveoschisis in both eyes. One month after the baseline presentation for myopic macular schisis, the patient presented with a paracentral scotoma in the left eye. Examination showed a submacular hemorrhage in the left eye. Optical coherence tomography of the left eye showed subretinal fluid and subretinal hyperreflective material in the fovea, suggestive of exudative myopia, and a small full-thickness MH (diameter 86 µm). After anti-vascular endothelial growth factor injections, the CNV showed interval improvement; however, a larger full-thickness MH (diameter 287 µm) developed in the left eye. Conclusions: A full-thickness MH developed secondary to CNV, leading to foveal dehiscence in an eye with baseline macular schisis.

ATYPICAL PROLIFERATIVE RETINOPATHY AS THE PRESENTING FEATURE OF CHRONIC MYELOID LEUKEMIA IN A PATIENT WITH DIABETES MELLITUS.

PURPOSE: To describe a case of proliferative retinopathy as the presenting manifestation of chronic myeloid leukemia in a patient with poorly controlled diabetes mellitus (DM). Undiagnosed chronic myeloid leukemia in a patient with pre-existing poorly controlled DM is rarely encountered but must be recognized to treat appropriately with systemic chemotherapy. Significant fundus finding overlaps with DM making the recognition of chronic myeloid leukemia challenging. METHODS: Case report. RESULTS: Fundoscopy revealed scattered dot-blot hemorrhages, venous beading, and numerous Roth spots in all quadrants, in both eyes. In the right eye, there was also a vitreous hemorrhage with evidence of neovascularization near the inferior arcade. Intravenous fluorescein angiography showed significant peripheral capillary nonperfusion without evidence of exudation in both eyes. No macular edema was observed on optical coherence tomography. A review of systems and physical examination was negative for constitutional symptoms, lymphadenopathy, organomegaly, and other symptoms. Retinal findings prompted a complete blood count, which revealed significant leukocytosis. A bone marrow biopsy confirmed a diagnosis of chronic myeloid leukemia. Systemic chemotherapy and pan-retinal photocoagulation successfully normalized the leukocyte count and resolved the vitreous hemorrhage and neovascularization. CONCLUSION: The presence of numerous Roth spots in all quadrants, extensive areas of capillary nonperfusion on intravenous fluorescein angiography, and neovascularization in the absence of exudation or macular edema should prompt investigations to rule out hematologic disorders.

RP2 X-LINKED RETINITIS PIGMENTOSA CARRIER STATE PRESENTING WITH VASCULAR LEAKAGE AND UNILATERAL MACULAR ATROPHY.

PURPOSE: We describe the unusual clinical presentation of a 33-year-old woman subsequently identified as a carrier of RP2-associated X-linked retinitis pigmentosa. METHODS: Case report. RESULTS: A 33-year-old woman without a known family history of retinal disease presented with unilateral reduced visual acuity and central scotoma in the left eye. Examination showed underlying macular atrophy in the left eye and a bilateral tapetal-like reflex. Full-field electroretinogram was abnormal in the left eye but normal in the right eye. Notable findings on wide-field imaging included bilateral peripheral vascular leakage on fluorescein angiography and a bilaterally symmetric radial pattern of hyperfluorescence on fundus autofluorescence. Genetic testing demonstrated a pathogenic variant in the gene RP2 confirming that she was a carrier of X-linked retinitis pigmentosa. CONCLUSION: We describe clinical features of the carrier state of RP2-XLRP and expand potential findings to include peripheral vascular leakage. This case highlights the importance of awareness of the carrier state, particularly if a family history cannot be provided.

Deep phenotypic characterization of the retinal dystrophy in patients with RNU4ATAC-associated Roifman syndrome.

PURPOSE: To characterize the retinal phenotype in RNU4ATAC-associated Roifman syndrome. METHODS: Ten patients (including 8 males) with molecularly confirmed Roifman syndrome underwent detailed ophthalmologic evaluation including fundus imaging, fundus autofluorescence (FAF) imaging, spectral-domain optical coherence tomography (SD-OCT), and electroretinography (ERG). Six patients had follow-up eye exams. All patients also underwent comprehensive examination for features of extra-retinal Roifman syndrome. RESULTS: All patients had biallelic RNU4ATAC variants. Nyctalopia was common (7/10). Visual acuity at presentation ranged from 20/20 to 20/200 (Age Range: 5-41 years). Retinal exam revealed features of generalized retinopathy with mid-peripheral pigment epithelial changes. A para or peri-foveal ring of hyper-autofluorescence was the commonest FAF abnormality noted (6/8). The SD-OCT demonstrated relative preservation of the foveal ellipsoid zone in six cases; associated features included cystoid changes (5/10) and posterior staphyloma (3/10). The ERG was abnormal in all patients; nine showed generalized rod-cone dystrophy, whilst one patient with sectoral retinal involvement only had isolated rod dystrophy (20 years old). On follow-up examination (Mean duration: 8.16 years), progressive loss of visual acuity (2/6), mid-peripheral retinal atrophy (3/6) or shortening of ellipsoid zone width (1/6) were observed. CONCLUSION: This study has characterized the retinal phenotype in RNU4ATAC-associated Roifman syndrome. Retinal involvement is universal, early-onset, and overall, the retinal and FAF features are consistent with rod-cone degeneration that is slowly progressive over time. The sub-foveal retinal ultrastructure is relatively preserved in majority of patients. Phenotypic variability independent of age exists, and more study of allelic- and sex-based determinants of disease severity are necessary.

Prevalence and predictors for being unscreened for diabetic retinopathy: a population-based study over a decade.

OBJECTIVE: To determine the population-level predictors for being unscreened for diabetic retinopathy (DR) among individuals with diabetes in a developed country. DESIGN: A retrospective population-based repeated-cross-sectional study. PARTICIPANTS: All individuals with diabetes (types 1 and 2) aged ≥20 years in the universal health care system in Ontario were identified in the 2011-2013 and 2017-2019 time periods. METHODS: The Mantel-Haenszel test was used for the relative risk (RR) comparison of subcategories stratified by the 2 cross-sectional time periods. RESULTS: A total of 1 145 645 and 1 346 578 individuals with diabetes were identified in 2011-2013 and 2017-2019, respectively. The proportion of patients unscreened for DR declined very slightly from 35% (n = 405 967) in 2011-2013 to 34% (n = 455 027) in 2017-2019 of the population with diabetes (RR = 0.967; 95% CI, 0.964-0.9693; p < 0.0001). Young adults aged 20-39 years of age had the highest proportion of unscreened patients (62% and 58% in 2011-2013 and 2017-2019, respectively). Additionally, those who had a lower income quintile (RR = 1.039; 95% CI, 1.036-1.044; p < 0.0001), were recent immigrants (RR = 1.286; 95% CI, 1.280-1.293; p < 0.0001), lived in urban areas (RR = 1.149; 95% CI, 1.145-1.154; p < 0.0001), had a mental health history (RR = 1.117; 95% CI, 1.112-1.122; p < 0.0001), or lacked a connection to a primary care provider (RR = 1.656; 95% CI, 1.644-1.668; p < 0.0001) had a higher risk of being unscreened. CONCLUSIONS: This population-based study suggests that over 1 decade, 33% of individuals with diabetes are unscreened for DR, and young age, low income, immigration, residing in a large city, mental health illness, and no primary care access are the main predictors.

Generation and clonal isolation of retinal stem cells from human embryonic stem cells.

Retinal stem cells (RSCs) are present within the pigmented ciliary epithelium (CE) of the adult human eye and produce progeny that differentiate in vitro into all neural retinal subtypes and retinal pigmented epithelium (RPE). We hypothesized that a RSC population, similar to the adult CE-derived RSC, is contained within pigmented colonies that arise in long-term cultures of human embryonic stem cells (hESCs) suggested to recapitulate retinal development in vitro. Single pigmented hESC-derived cells were isolated and plated in serum-free media containing growth factors and, after 2 weeks, clonal sphere colonies containing both pigmented and non-pigmented cells were observed. These colonies expressed the early retinal transcription factors Rx, Chx10 and Pax6, and could be dissociated and replated as single cells to form secondary clonal colonies. When allowed to differentiate, expression of markers for both RPE and neurons was observed. Rhodopsin expression was detected after explant co-culture and transplantation into the developing mouse eye as well as following treatment with soluble factors in vitro. We show that RSCs emerge in an in vitro model of retinal development and are a potential source of human photoreceptors for use in transplantation.

Spontaneous Closure of an Idiopathic Full-Thickness Macular Hole: A Literature Review.

Purpose: This work reviews the literature regarding spontaneous closure of idiopathic full-thickness macular holes (FTMHs). Methods: Literature on patients with spontaneous idiopathic FTMH closure was reviewed via Ovid MEDLINE, EMBASE, and PubMed through July 16, 2020. A total of 27 of 66 identified articles were included. Results: A total of 68 eyes had spontaneous closure. Of the patients, 62.7% were women and the average age was 67.5 years. Visual acuity improved from Snellen 20/78 to 20/33 post closure. The average hole diameter was 176.8 µm; the largest was 350 µm. Most were stage 2 according to Gass and of small size according to International Vitreomacular Traction Study Group (IVTS) staging. The predominant classification system in recent literature is IVTS staging. The average optical coherence tomography-observed closure time was 4.5 months. Conclusions: On review, reported spontaneous closure rates of all idiopathic FTMH range from 3% to 15%, and no demographic subgroups are more likely to have closure. Holes ≤250 µm have higher closure rates (22.2%) than those in the range of >250 to 400 µm (13.3%) and ≥400 µm (0%). Closure is associated with favorable visual outcomes, and retinal bridging via glial cells is likely critical to closure. These determinations were based on limited numbers; prospective studies are needed to further ascertain rate, mechanism, and characteristics. IVTS staging provides reliable reporting and insight into whether FTMH can be observed before surgery.

Switching between anti-VEGF agents in the management of refractory diabetic macular edema: A systematic review.

Refractory diabetic macular edema (DME) to monthly intravitreal anti-vascular endothelial growth factor (VEGF) monotherapy has a prevalence of approximately 40% in landmark clinical trials. Options for these patients include use of intravitreal steroids, focal laser, or switching to an alternative anti-VEGF agent. We summarize the key conclusions from studies analyzing the efficacy of switching anti-VEGF agents for refractory DME. Twenty-four studies were included in analysis. The most common definitions of refractory in the included studies were a central retinal thickness (CRT) greater than 300µm or a reduction in CRT less than 10% after at least 3-6 prior anti-VEGF injections. Switching to intravitreal aflibercept (IVA) from either intravitreal ranibizumab (IVR) or bevacizumab (IVB) is associated with moderate to significant improvement in central subfield thickness and may be an appropriate choice for patients with refractory DME. The improvement in retinal thickness and edema is typically seen after the first 3 injections of IVA post-switch. Switching to IVR has also demonstrated improvement in CRT at 3-6 months post switch in large sample population studies. Future studies are required to elucidate the ideal time point for a switch in anti-VEGF agent or which patients would benefit from this change.