Cell Atlas of The Human Fovea and Peripheral Retina

Most irreversible blindness results from retinal disease. To advance our understanding of the etiology of blinding diseases, we used single-cell RNA-sequencing (scRNA-seq) to analyze the transcriptomes of ~85,000 cells from the fovea and peripheral retina of seven adult human donors. Utilizing computational methods, we identified 58 cell types within 6 classes: photoreceptor, horizontal, bipolar, amacrine, retinal ganglion and non-neuronal cells. Nearly all types are shared between the two retinal regions, but there are notable differences in gene expression and proportions between foveal and peripheral cohorts of shared types. We then used the human retinal atlas to map expression of 636 genes implicated as causes of or risk factors for blinding diseases. Many are expressed in striking cell class-, type-, or region-specific patterns. Finally, we compared gene expression signatures of cell types between human and the cynomolgus macaque monkey, Macaca fascicularis. We show that over 90% of human types correspond transcriptomically to those previously identified in macaque, and that expression of disease-related genes is largely conserved between the two species. These results validate the use of the macaque for modeling blinding disease, and provide a foundation for investigating molecular mechanisms underlying visual processing.

Cell atlas of aqueous humor outflow pathways in eyes of humans and four model species provides insight into glaucoma pathogenesis

Increased intraocular pressure (IOP) represents a major risk factor for glaucoma, a prevalent eye disease characterized by death of retinal ganglion cells; lowering IOP is the only proven treatment strategy to delay disease progression. The main determinant of IOP is the equilibrium between production and drainage of aqueous humor, with compromised drainage generally viewed as the primary contributor to dangerous IOP elevations. Drainage occurs through two pathways in the anterior segment of the eye called conventional and uveoscleral. To gain insights into the cell types that comprise these pathways, we used high-throughput single-cell RNA sequencing (scRNAseq). From ∼24,000 single-cell transcriptomes, we identified 19 cell types with molecular markers for each and used histological methods to localize each type. We then performed similar analyses on four organisms used for experimental studies of IOP dynamics and glaucoma: cynomolgus macaque (Macaca fascicularis), rhesus macaque (Macaca mulatta), pig (Sus scrofa), and mouse (Mus musculus). Many human cell types had counterparts in these models, but differences in cell types and gene expression were evident. Finally, we identified the cell types that express genes implicated in glaucoma in all five species. Together, our results provide foundations for investigating the pathogenesis of glaucoma and for using model systems to assess mechanisms and potential interventions.

Cell atlas of the human ocular anterior segment: Tissue-specific and shared cell types

The anterior segment of the eye consists of the cornea, iris, ciliary body, crystalline lens, and aqueous humor outflow pathways. Together, these tissues are essential for the proper functioning of the eye. Disorders of vision have been ascribed to defects in all of them; some disorders, including glaucoma and cataract, are among the most prevalent causes of blindness in the world. To characterize the cell types that compose these tissues, we generated an anterior segment cell atlas of the human eye using high-throughput single-nucleus RNA sequencing (snRNAseq). We profiled 195,248 nuclei from nondiseased anterior segment tissues of six human donors, identifying >60 cell types. Many of these cell types were discrete, whereas others, especially in the lens and cornea, formed continua corresponding to known developmental transitions that persist in adulthood. Having profiled each tissue separately, we performed an integrated analysis of the entire anterior segment, revealing that some cell types are unique to a single structure, whereas others are shared across tissues. The integrated cell atlas was then used to investigate cell type-specific expression patterns of more than 900 human ocular disease genes identified through either Mendelian inheritance patterns or genome-wide association studies.

Endophthalmitis After Intravitreal Injections in Patients With Self-reported Iodine Allergy

PURPOSE

To present cases of endophthalmitis following intravitreal injections where povidone-iodine (PI) was not used as part of the surgical preparation.

DESIGN

Retrospective case series.

METHODS

All cases of presumed injection-related endophthalmitis presenting to the Massachusetts Eye and Ear Infirmary between June 2008 and November 2014 and Dean McGee Eye Institute between January 2010 and January 2015 were identified. Patients who did not receive PI preparation owing to documented self-reported allergy to iodine, iodine-containing contrast material, or shellfish were identified and their injection histories and clinical courses reviewed.

RESULTS

The combined rate of postinjection endophthalmitis at these 2 centers was 0.019%. Among 42 patients with postinjection endophthalmitis, 5 (11.9%) did not receive PI prophylaxis. The mean number of intravitreal injections without PI before the development of endophthalmitis was 10.6 with a 9.4% rate of endophthalmitis (5 cases per 53 injections). All patients underwent tap-and-inject procedures with vancomycin 1 mg and ceftazidime 2 mg. Two patients did not receive PI at the time of tap and inject; 1 of these patients required subsequent pars plana vitrectomy for worsening clinical course. Cultures were positive in 4 of 5 cases; all positive cultures grew coagulase-negative Staphylococcus. All patients who received subsequent intravitreal injections received PI prophylaxis without allergic reactions, thus demonstrating a lack of true PI allergy.

CONCLUSIONS

Avoiding PI owing to self-reported iodine "allergy" risks substantial ocular morbidity. Allergy testing can be pursued per patient request or in rare cases of suspected true PI allergy; however, in cases where delayed treatment would adversely affect visual outcome, the clinician should feel confident that minimal allergic risk exists.

Transcriptomic analysis of the ocular posterior segment completes a cell atlas of the human eye

Although the visual system extends through the brain, most vision loss originates from defects in the eye. Its central element is the neural retina, which senses light, processes visual signals, and transmits them to the rest of the brain through the optic nerve (ON). Surrounding the retina are numerous other structures, conventionally divided into anterior and posterior segments. Here, we used high-throughput single-nucleus RNA sequencing (snRNA-seq) to classify and characterize cells in six extraretinal components of the posterior segment: ON, optic nerve head (ONH), peripheral sclera, peripapillary sclera (PPS), choroid, and retinal pigment epithelium (RPE). Defects in each of these tissues are associated with blinding diseases-for example, glaucoma (ONH and PPS), optic neuritis (ON), retinitis pigmentosa (RPE), and age-related macular degeneration (RPE and choroid). From ~151,000 single nuclei, we identified 37 transcriptomically distinct cell types, including multiple types of astrocytes, oligodendrocytes, fibroblasts, and vascular endothelial cells. Our analyses revealed a differential distribution of many cell types among distinct structures. Together with our previous analyses of the anterior segment and retina, the data presented here complete a "Version 1" cell atlas of the human eye. We used this atlas to map the expression of >180 genes associated with the risk of developing glaucoma, which is known to involve ocular tissues in both anterior and posterior segments as well as the neural retina. Similar methods can be used to investigate numerous additional ocular diseases, many of which are currently untreatable.

Efficacy of a Single Administration of 5% Povidone-Iodine in the Treatment of Adenoviral Conjunctivitis

PURPOSE

To evaluate the safety and efficacy of a single, in-office administration of 5% povidone-iodine (PVP-I) compared to artificial tears (AT) for adenoviral conjunctivitis (Ad-Cs).

DESIGN

Double-masked pilot randomized trial.

METHODS

Patients presenting with presumed adenoviral conjunctivitis were screened at 9 U.S. clinics.

INCLUSION CRITERIA

≥18 years of age, symptoms ≤4 days, and a positive AdenoPlus test.

EXCLUSION CRITERIA

thyroid disease, iodine allergy, recent ocular surgery, and ocular findings inconsistent with early-stage Ad-Cs. Randomization was to a single administration of 5% PVP-I or AT in 1 eye and examinations on days 1-2, 4, 7, 14, and 21 with conjunctival swabs taken at each visit for quantitative polymerase chain reaction. Primary outcome was percent reduction from peak viral load. Secondary outcomes were improvement in clinical signs and symptoms.

RESULTS

Of 56 patients randomized, 28 had detectable viral titers at baseline. Day 4 posttreatment, viral titers in the 5% PVP-I and AT groups were 2.5% ± 2.7% and 14.4% ± 10.5% of peak, respectively (P = .020). Severity of participant-reported tearing, lid swelling, and redness as well as clinician-graded mucoid discharge, bulbar redness, and bulbar edema were lower in the 5% PVP-I group than AT group on day 4 (P < .05). After day 4, viral titers and severity of signs and symptoms decreased markedly in both groups and no differences between groups were detected.

CONCLUSIONS

Pilot data suggest a single, in-office administration of 5% PVP-I could reduce viral load and hasten improvement of clinical signs and symptoms in patients with Ad-Cs.

Treatment Course of Patients with Exudative Age-Related Macular Degeneration Using Ocular Hypotensives

Purpose

To characterize the visual outcomes and the treatment course of patients with exudative age-related macular degeneration (AMD) based on ocular hypotensive use.

Design

A matched retrospective cohort study of patients enrolled in Kaiser Permanente Southern California health plan was conducted. Patients taking ocular hypotensives were identified using pharmacy dispensing data and were matched to controls to compare visual acuity, number of anti-VEGF injections, and conversation to secondary anti-VEGF agents in the first year of treatment. Subgroup analysis was performed based on the number of ocular hypotensive agents (0, 1, 2 or 3+ agents) and drug class (aqueous suppressants and prostaglandin analogs).

Results

A total of 234 patients patients were examined. Baseline and final visual acuity did not significantly differ between drop users and controls, including on subgroup analysis. The average number of anti-VEGF injections did not differ between drop users and controls (6.1 vs 6.2, p=0.97), nor did the percentage of patients who were switched to a second-line anti-VEGF agent (23.9% vs 17.9%, p=0.26). Subgroup analysis did not reveal significant differences in the number of anti-VEGF injections and the percentage of patients switched to secondary agents, with patients receiving 6 ±1 injections across regardless of the number or class of ocular hypotensive agents used.

Conclusion

Patients with concurrent glaucoma and exudative AMD have similar visual outcomes and treatment courses compared to those not taking ocular hypotensives. Although aqueous suppressants have been suggested to prolong anti-VEGF residence time, patients using these agents did not demonstrate visual benefit or a reduced injection burden in this series.

[Recent Research Efforts to Achieve Neuroprotection, Progression and Treatment of Glaucoma]

Glaucoma is a neurodegenerative disease that leads to irreversible blindness over time. Its defining feature is the loss of retinal ganglion cells (RGCs) in the eye and their axons in the optic nerve. Increased intraocular pressure (IOP) is a major risk factor for the development of glaucoma, but is neither necessary nor sufficient for the disease and its progression; this motivates research and development of new strategies for the detection and treatment of glaucoma that focus on neuroprotection - protection of RGCs from dying. In addition, for diagnosis and treatment by reducing IOP, new approaches have been developed in recent years. This article reviews current theories of pathophysiological mechanisms underlying glaucoma and recent research - with a focus on neuroprotection and current preclinical and clinical studies to improve the diagnosis and treatment of glaucoma.

Integrating genetic regulation and single-cell expression with GWAS prioritizes causal genes and cell types for glaucoma

Primary open-angle glaucoma (POAG), characterized by retinal ganglion cell death, is a leading cause of irreversible blindness worldwide. However, its molecular and cellular causes are not well understood. Elevated intraocular pressure (IOP) is a major risk factor, but many patients have normal IOP. Colocalization and Mendelian randomization analysis of >240 POAG and IOP genome-wide association study (GWAS) loci and overlapping expression and splicing quantitative trait loci (e/sQTLs) in 49 GTEx tissues and retina prioritizes causal genes for 60% of loci. These genes are enriched in pathways implicated in extracellular matrix organization, cell adhesion, and vascular development. Analysis of single-nucleus RNA-seq of glaucoma-relevant eye tissues reveals that the POAG and IOP colocalizing genes and genome-wide associations are enriched in specific cell types in the aqueous outflow pathways, retina, optic nerve head, peripapillary sclera, and choroid. This study nominates IOP-dependent and independent regulatory mechanisms, genes, and cell types that may contribute to POAG pathogenesis.

Natural history of adenoviral conjunctivitis in a US-based population: Viral load, signs, and symptoms

PURPOSE

To report the clinical signs, symptoms, and viral clearance in individuals in the United States with adenoviral conjunctivitis (Ad-Cs).

METHODS

Individuals ≥ 18 years presenting within 4 days of symptoms of Ad-Cs who met eligibility criteria and tested positive with both point-of-care immunoassay antigen and quantitative polymerase chain reaction (qPCR) testing were enrolled. Patient-reported symptoms, clinician-graded signs, and qPCR viral titers were collected at baseline, days 1-2, 4 (days 3-5), 7 (days 6-10), 14 (days 11-17) and 21 (days 18-21).

RESULTS

There was no detectable viral titers by the day 14 visit in 6/8 patients. By day 21, there was no detectable viral titers in the 7 participants who completed the visit; however, signs and symptoms persisted including: blurry vision (5/7), discomfort (2/7) or redness (1/7). Masked clinicians also noted conjunctival redness (4/7), follicular conjunctivitis (4/7) and bulbar edema (3/7).

CONCLUSION

Many patient-reported symptoms and clinical signs persist after viral titers are no longer detectable by qPCR. Using clinical signs and symptoms to determine quarantine duration may result in patients being furloughed longer than the time that the patient is infectious.

Designing the next generation of clinical trials in intermediate AMD-a consensus driven, pragmatic, proof of concept early intervention study

A greater understanding of the pathophysiology of AMD has yielded potential therapeutic strategies for slowing vision loss. Structural imaging biomarkers and novel functional outcomes, both under intensive study as surrogate endpoints in AMD clinical trials, are new granular tools needed to assess disease progression and follow response to therapy. These advances have created, for the first time, the possibility to intervene early in AMD, and to measure success in a time frame feasible for clinical trials. At the 2024 Ryan Initiative for Macular Research (RIMR) meeting, a consensus was reached for design of a hypothetical, pragmatic, proof of concept, 24-month, early intervention study to determine the efficacy of an intervention in subjects with intermediate AMD (iAMD). Although further research is needed, using natural history cohorts and intervention trials to validate the proposed trial design and endpoints, this paper presents an AMD expert consensus framework for early AMD clinical trials, that we hope will also be useful for therapeutic developers and regulators. Viable clinical trial strategies are needed to develop treatments that slow the progression of AMD prior to the development of vision-threatening late AMD; this consensus document should aid in reaching this goal.

Transcriptomic Analysis of the Ocular Posterior Segment Completes a Cell Atlas of the Human Eye

Although the visual system extends through the brain, most vision loss originates from defects in the eye. Its central element is the neural retina, which senses light, processes visual signals, and transmits them to the rest of the brain through the optic nerve (ON). Surrounding the retina are numerous other structures, conventionally divided into anterior and posterior segments. Here we used high-throughput single nucleus RNA sequencing (snRNA-seq) to classify and characterize cells in the extraretinal components of the posterior segment: ON, optic nerve head (ONH), peripheral sclera, peripapillary sclera (PPS), choroid, and retinal pigment epithelium (RPE). Defects in each of these tissues are associated with blinding diseases - for example, glaucoma (ONH and PPS), optic neuritis (ON), retinitis pigmentosa (RPE), and age-related macular degeneration (RPE and choroid). From ∼151,000 single nuclei, we identified 37 transcriptomically distinct cell types, including multiple types of astrocytes, oligodendrocytes, fibroblasts, and vascular endothelial cells. Our analyses revealed a differential distribution of many cell types among distinct structures. Together with our previous analyses of the anterior segment and retina, the new data complete a "Version 1" cell atlas of the human eye. We used this atlas to map the expression of >180 genes associated with the risk of developing glaucoma, which is known to involve ocular tissues in both anterior and posterior segments as well as neural retina. Similar methods can be used to investigate numerous additional ocular diseases, many of which are currently untreatable.