Glutaminase deficiency in rod photoreceptors disrupts nonessential amino acid levels to activate the integrated stress response and induce rapid degeneration

The bioenergetic demand of photoreceptors rivals that of cancer cells, and numerous metabolic similarities exist between these cells. Glutamine (Gln) anaplerosis via the tricarboxylic acid (TCA) cycle provides biosynthetic intermediates and is a hallmark of cancer metabolism. In this process, Gln is first converted to glutamate via glutaminase (GLS), which is a crucial pathway in many cancer cells. To date, no study has been undertaken to examine the role of Gln metabolism in vivo in photoreceptors. Here, mice lacking GLS in rod photoreceptors were generated. Animals lacking GLS experienced rapid photoreceptor degeneration with concomitant functional loss. Gln has multiple roles in metabolism including redox balance, biosynthesis of nucleotides and amino acids, and supplementing the TCA cycle. Few alterations were noted in redox balance. Unlabeled targeted metabolomics demonstrated few changes in glycolytic and TCA cycle intermediates, which corresponded with a lack of significant changes in mitochondrial function. GLS deficiency in rod photoreceptors did decrease the fractional labelling of TCA cycle intermediates when provided uniformly labeled 13C-Gln in vivo. However, supplementation with alpha-ketoglutarate provided only marginal rescue of photoreceptor degeneration. Nonessential amino acids, glutamate and aspartate, were decreased in the retina of mice lacking GLS in rod photoreceptors. In accordance with this amino acid deprivation, the integrated stress response (ISR) was found to be activated with decreased global protein synthesis. Importantly, supplementation with asparagine delayed photoreceptor degeneration to a greater degree than alpha-ketoglutarate. These data show that GLS-mediated Gln catabolism is essential for rod photoreceptor amino acid biosynthesis, function, and survival.

Classification and Growth Rate of Chorioretinal Atrophy after Voretigene Neparvovec-Rzyl for RPE65-Mediated Retinal Degeneration

PURPOSE

Classify the appearance and quantify the growth rate of chorioretinal atrophy in patients who received voretigene neparvovec-rzyl (VN) for RPE65-mediated retinal degeneration.

DESIGN

Multicenter retrospective analysis.

SUBJECTS

Patients who underwent subretinal VN injection at 5 institutions and demonstrated posterior-pole chorioretinal atrophy.

METHODS

Ultrawidefield scanning laser ophthalmoscopy or color fundus photos were assessed before and after subretinal VN. Atrophy was defined as regions with ≥ 2 of the following: (1) partial or complete retinal pigment epithelial depigmentation; (2) round shape; (3) sharp margins; and (4) increased visibility of choroidal vessels. Atrophy was qualitatively classified into different subtypes. All atrophy was manually segmented. Linear mixed-effects models with random slopes and intercepts were fit using atrophy area and square root of atrophy area.

MAIN OUTCOME MEASURES

Number of eyes with each atrophy pattern, and slopes of linear mixed-effects models.

RESULTS

Twenty-seven eyes from 14 patients across 5 centers developed chorioretinal atrophy after subretinal VN. A mean of 5.8 ± 2.7 images per eye obtained over 2.2 ± 0.8 years were reviewed, and atrophy was categorized into touchdown (14 eyes), nummular (15 eyes), and perifoveal (12 eyes) subtypes. Fifteen eyes demonstrated > 1 type of atrophy. Thirteen of 14 patients demonstrated bilateral atrophy. The slopes of the mixed-effects models of atrophy area and square root of atrophy area (estimate ± standard error) were 1.7 ± 1.3 mm2/year and 0.6 ± 0.2 mm/year for touchdown atrophy, 5.5 ± 1.3 mm2/year and 1.2 ± 0.2 mm/year for nummular atrophy, and 16.7 ± 1.8 mm2/year and 2.3 ± 0.2 mm/year for perifoveal atrophy. The slopes for each type of atrophy were significantly different in the square root of atrophy model, which best fit the data (P < 0.05).

CONCLUSIONS

Chorioretinal atrophy after subretinal VN for RPE65-mediated retinal degeneration developed according to a touchdown, nummular, and/or perifoveal pattern. Perifoveal atrophy grew the most rapidly, while touchdown atrophy grew the least rapidly. Understanding the causes of these findings, which are present in a minority of patients, merits further investigation.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Rod photoreceptor-specific deletion of cytosolic aspartate aminotransferase, GOT1, causes retinal degeneration

Photoreceptor cell death is the cause of vision loss in many forms of retinal disease. Metabolic dysfunction within the outer retina has been shown to be an underlying factor contributing to photoreceptor loss. Therefore, a comprehensive understanding of the metabolic pathways essential to photoreceptor health and function is key to identifying novel neuroprotective strategies. Glutamic-oxaloacetic transaminase 1 (Got1) encodes for a cytosolic aspartate aminotransferase that reversibly catalyzes the transfer of an amino group between glutamate and aspartate and is an important aspect of the malate-aspartate shuttle (MAS), which transfers reducing equivalents from the cytosol to the mitochondrial matrix. Previous work has demonstrated that the activity of this enzyme is highest in photoreceptor inner segments. Furthermore, ex vivo studies have demonstrated that the retina relies on aspartate aminotransferase for amino acid metabolism. Importantly, aspartate aminotransferase has been suggested to be an early biomarker of retinal degeneration in retinitis pigmentosa and a possible target for neuroprotection. In the present study, we characterized the effect of Got1 deletion on photoreceptor metabolism, function, and survival in vivo by using a rod photoreceptor-specific, Got1 knockout mouse model. Loss of the GOT1 enzyme from rod photoreceptors resulted in age-related photoreceptor degeneration with an accumulation of retinal aspartate and NADH and alterations in the expression of genes involved in the MAS, the tricarboxylic acid (TCA) cycle, and redox balance. Hence, GOT1 is critical to in vivo photoreceptor metabolism, function, and survival.

First-in-Human Gene Therapy Trial of AAV8-hCARp.hCNGB3 in Adults and Children With CNGB3-associated Achromatopsia

PURPOSE

To assess the safety and efficacy of AAV8-hCARp.hCNGB3 in participants with CNGB3-associated achromatopsia (ACHM).

DESIGN

Prospective, phase 1/2 (NCT03001310), open-label, nonrandomized clinical trial.

METHODS

The study enrolled 23 adults and children with CNGB3-associated ACHM. In the dose-escalation phase, adult participants were administered 1 of 3 AAV8-hCARp.hCNGB3 dose levels in the worse-seeing eye (up to 0.5 mL). After a maximum tolerated dose was established in adults, an expansion phase was conducted in children ≥3 years old. All participants received topical and oral corticosteroids. Safety and efficacy parameters, including treatment-related adverse events and visual acuity, retinal sensitivity, color vision, and light sensitivity, were assessed for 6 months.

RESULTS

AAV8-hCARp.hCNGB3 (11 adults, 12 children) was safe and generally well tolerated. Intraocular inflammation occurred in 9 of 23 participants and was mainly mild or moderate in severity. Severe cases occurred primarily at the highest dose. Two events were considered serious and dose limiting. All intraocular inflammation resolved following topical and systemic steroids. There was no consistent pattern of change from baseline to week 24 for any efficacy assessment. However, favorable changes were observed for individual participants across several assessments, including color vision (n = 6/23), photoaversion (n = 11/20), and vision-related quality-of-life questionnaires (n = 21/23).

CONCLUSIONS

AAV8-hCARp.hCNGB3 for CNGB3-associated ACHM demonstrated an acceptable safety and tolerability profile. Improvements in several efficacy parameters indicate that AAV8-hCARp.hCNGB3 gene therapy may provide benefit. These findings, with the development of additional sensitive and quantitative end points, support continued investigation.

Metabolic Alterations Caused by Simultaneous Loss of HK2 and PKM2 Leads to Photoreceptor Dysfunction and Degeneration

HK2 and PKM2 are two main regulators of aerobic glycolysis. Photoreceptors (PRs) use aerobic glycolysis to produce the biomass necessary for the daily renewal of their outer segments. Previous work has shown that HK2 and PKM2 are important for the normal function and long-term survival of PRs but are dispensable for PR maturation, and their individual loss has opposing effects on PR survival during acute nutrient deprivation. We generated double conditional (dcKO) mice lacking HK2 and PKM2 expression in rod PRs. Western blotting, immunofluorescence, optical coherence tomography, and electroretinography were used to characterize the phenotype of dcKO animals. Targeted and stable isotope tracing metabolomics, qRT-PCR, and retinal oxygen consumption were performed. We show that dcKO animals displayed early shortening of PR inner/outer segments, followed by loss of PRs with aging, much more rapidly than either knockout alone without functional loss as measured by ERG. Significant alterations to central glucose metabolism were observed without any apparent changes to mitochondrial function, prior to PR degeneration. Finally, PR survival following experimental retinal detachment was unchanged in dcKO animals as compared to wild-type animals. These data suggest that HK2 and PKM2 have differing roles in promoting PR neuroprotection and identifying them has important implications for developing therapeutic options for combating PR loss during retinal disease.

Flow cytometric method for the detection and quantification of retinal cell death and oxidative stress

Retinal cell death is the major cause of vision loss in many forms of blinding retinal disease. A plethora of research is focused on understanding the mechanisms of retinal cell death to identify potential neuroprotective strategies that prevent vision loss in these diseases. Traditionally, histological techniques have been used to determine the type and extent of cell death in the retina. These techniques, such as TUNEL labeling and immunohistochemistry, are laborious and time consuming, resulting in low throughput and variable results depending on the experimenter. To increase throughput and reduce variability, we developed several flow cytometry-based assays to detect and quantify retinal cell death. The methods and accompanying data presented demonstrate that flow cytometry can readily detect both retinal cell death and oxidative stress and importantly, the efficacy of neuroprotective agents. These methods will be of interest to investigators looking to increase throughput and efficiency without compromising sensitivity as the methods herein reduce analysis time from several months to less than a week. As such, the flow cytometry methods presented have the potential to expedite research efforts focused on developing novel strategies for retinal cell neuroprotection.

The impact of the COVID-19 lockdown on retinopathy of prematurity screening and management in the United States: a multicenter study

PURPOSE

To study the effect of the pandemic-related lockdown (physical distance measures and movement restrictions) on the characteristics and management of retinopathy of prematurity (ROP).

METHODS

In this controlled, multicenter cohort study, the medical records of patients born prematurely and screened for ROP in the neonatal intensive care unit during four time periods were reviewed retrospectively: (1) November 1, 2018, to March 15, 2019; (2) March 16, 2019, to August 2, 2019 (lockdown control period); (3) November 1, 2019, to March 15, 2020; and (4) March 16, 2020-August 2, 2020.

RESULTS

A total of 1,645 patients met inclusion criteria. Among the 1,633 patients with complete data, mean gestational age (GA) at birth was 28.2, 28.4, 28.0, and 28.3 weeks across time periods 1 to 4, respectively (P = 0.16). The mean birth weight of all patients was 1079.1 ± 378.60 g, with no significant variation across time periods (P = 0.08). There were fewer patients screened during the lockdown period (n = 411) compared with the period immediately before (n = 491) and the same period in the prior year (n = 533). Significantly more patients were screened using indirect ophthalmoscopy, compared to digital imaging (telemedicine), during the lockdown (P < 0.01). There were 11.7%, 7.7%, 9.0%, and 8.8% of patients requiring treatment in each time period, respectively (P = 0.42), with a median postmenstrual age at initial treatment of 37.2, 36.45, 37.1, and 36.3 weeks, respectively (P = 0.32).

CONCLUSIONS

We recorded a decrease in the number of infants meeting criteria for ROP screening during the lockdown. The GA at birth and birth weight did not differ. Significantly more infants were screened with indirect ophthalmoscopy, compared to digital imaging, during the lockdown.

Development of Novel Small-Molecule Activators of Pyruvate Kinase Muscle Isozyme 2, PKM2, to Reduce Photoreceptor Apoptosis

Treatment options are lacking to prevent photoreceptor death and subsequent vision loss. Previously, we demonstrated that reprogramming metabolism via the pharmacologic activation of PKM2 is a novel photoreceptor neuroprotective strategy. However, the features of the tool compound used in those studies, ML-265, preclude its advancement as an intraocular, clinical candidate. This study sought to develop the next generation of small-molecule PKM2 activators, aimed specifically for delivery into the eye. Compounds were developed that replaced the thienopyrrolopyridazinone core of ML-265 and modified the aniline and methyl sulfoxide functional groups. Compound 2 demonstrated that structural changes to the ML-265 scaffold are tolerated from a potency and efficacy standpoint, allow for a similar binding mode to the target, and circumvent apoptosis in models of outer retinal stress. To overcome the low solubility and problematic functional groups of ML-265, compound 2's efficacious and versatile core structure for the incorporation of diverse functional groups was then utilized to develop novel PKM2 activators with improved solubility, lack of structural alerts, and retained potency. No other molecules are in the pharmaceutical pipeline for the metabolic reprogramming of photoreceptors. Thus, this study is the first to cultivate the next generation of novel, structurally diverse, small-molecule PKM2 activators for delivery into the eye.

Characteristics of a Three-Generation Family with Stickler Syndrome Type I Carrying Two Different COL2A1 Mutations

Stickler Syndrome is typically characterized by ophthalmic manifestations including vitreous degeneration and axial lengthening that predispose to retinal detachment. Systemic findings consist of micrognathia, cleft palate, sensorineural hearing loss, and joint abnormalities. COL2A1 mutations are the most common, however, there is a lack of genotype-phenotype correlations. Retrospective, single-center case series of a three-generation family. Clinical features, surgical requirements, systemic manifestations, and genetic evaluations were collected. Eight individuals clinically displayed Stickler Syndrome, seven of whom had genetic confirmation, and two different COL2A1 mutations (c.3641delC and c.3853G>T) were identified. Both mutations affect exon 51, but display distinct phenotypes. The c.3641delC frameshift mutation resulted in high myopia and associated vitreous and retinal findings. Individuals with the c.3853G>T missense mutation exhibited joint abnormalities, but mild ocular manifestations. One individual in the third generation was biallelic heterozygous for both COL2A1 mutations and showed ocular and joint findings in addition to autism and severe developmental delay. These COL2A1 mutations exhibited distinct eye vs. joint manifestations. The molecular basis for these phenotypic differences remains unknown and demonstrates the need for deep phenotyping in patients with Stickler syndrome to correlate COL2A1 gene function and expression with ocular and systemic findings.

Retinal Neovascularization in Posterior Polar Annular Choroidal Dystrophy

This case report describes the development of posterior subcapsular cataract and retinal neovascularization in a patient with posterior polar annular choroidal dystrophy.

Late Vitreoretinal Complications of Regressed Retinopathy of Prematurity: Retinal Break, Vitreous Hemorrhage, and Retinal Detachment

PURPOSE

To investigate late vitreoretinal complications and visual outcomes in patients with regressed retinopathy of prematurity (ROP) with or without prior treatment.

DESIGN

International, multicenter, noncomparative retrospective case series.

PARTICIPANTS

We analyzed 264 eyes of 238 patients from 13 centers worldwide who developed vitreoretinal complications (retinal detachment [RD], vitreous hemorrhage [VH], or retinal break) ≥ 2 years after resolution of acute ROP.

METHODS

Each participant was assigned to 1 of 3 groups (the RD, VH, and retinal break groups) according to their primary diagnosis. The average age at presentation, visual acuities, refractive error, axial length, gestational age, birth weight, acute ROP classification, prior treatments for acute ROP, postoperative visual acuity (VA), and concomitant eye conditions in the 3 groups were documented and compared.

MAIN OUTCOME MEASURES

Clinical features and visual outcomes of late vitreoretinal complications in patients with regressed ROP.

RESULTS

A total of 264 eyes of 238 patients were included. The prior acute ROP status was comparable among the 3 groups, except that the VH group had a higher proportion of patients with type 1 ROP (P = 0.03) and prior treatment (P < 0.001) than the other groups. The average age at presentation was earlier in the RD (20.3 ± 15.5 years) and VH (21.4 ± 18.9 years) groups than in the retinal break group (31.9 ± 18.2 years; P < 0.001). The retinal break group had the best presenting best-corrected VA, followed by the RD and VH groups (P < 0.001). Surgical intervention improved VA in both the RD and VH groups (both P < 0.05). The overall trend of VA was the most favorable in the retinal break group, followed by that in the VH and RD groups. Cicatricial changes in the fellow retina were observed in > 90% of patients with unilateral involvement.

CONCLUSIONS

Infants with acute ROP remain at a high risk of vision-threatening complications throughout childhood and adulthood. Continual follow-up of patients with ROP is important. When severe complications, such as RD or VH, are detected, timely surgical intervention is necessary to ensure favorable visual outcomes in these patients.

Synthetic high-density lipoprotein nanoparticles delivering rapamycin for the treatment of age-related macular degeneration

Synthetic high-density lipoprotein (sHDL) and rapamycin (Rap) have both been shown to be potential treatments for age-related macular degeneration (AMD). The low aqueous solubility of Rap, however, limits its therapeutic utility. Here we used an Apolipoprotein A-I mimetic peptide and phospholipid-based sHDL for the intravitreal delivery of Rap. By incorporation of Rap in sHDL nanoparticles (sHDL-Rap), we achieve 125-fold increase in drug aqueous concentration. When applied in vitro to retinal pigment epithelium cells, sHDL-Rap exhibited the abilities to efflux cholesterol, neutralize endotoxin, and suppress NF-κB activation. As an mTOR inhibitor, Rap induced autophagy and inhibited NF-κB-mediated pro-inflammatory signaling. Additionally, a greater reduction in lipofuscin accumulation and increased anti-inflammatory effects were achieved by sHDL-Rap relative to free drug or sHDL alone. In vivo studies demonstrated that sHDL reached the target retina pigment epithelium (RPE) layer following intravitreal administration in rats. These results suggest that sHDL-Rap holds potential as a treatment for AMD.

A Caveat about Financial Incentives for Anti-Vascular Endothelial Growth Factor Therapy for Diabetic Retinopathy

PURPOSE

To highlight the financial incentive to the physician of choosing an intravitreal anti-VEGF based strategy for treatment of non-proliferative and proliferative diabetic retinopathy and its possible risks to the patient and costs to the healthcare system.

DESIGN

Perspective, with retrospective cost and profit analysis METHODS: Review and synthesis of selected literature on the treatment of diabetic retinopathy, with interpretation of activity- and time-based costing of an intravitreal aflibercept strategy for diabetic retinopathy. Data from the DRCR Retina Network Protocols W and AB and from the PANORAMA trial are used to illustrate the potential financial incentive underlying such a treatment strategy.

RESULTS

Physician treatment algorithms for diabetic vitreous hemorrhage and non-proliferative diabetic retinopathy may be influenced by the substantial financial incentives intravitreal aflibercept strategies present despite functional equivalence with alternative, less profitable, strategies. For example, pursuing an intravitreal aflibercept based strategy for diabetic vitreous hemorrhage presents a 76% increased profit over pars plana vitrectomy with laser, with equivalent functional outcomes. For non-proliferative diabetic retinopathy, preventative aflibercept injections represent a potential 414% increase in profit over observation and an increased cost of $12164 to $17542 over two years per patient, with no improvement in visual function. These findings demonstrate that there may be misaligned financial incentives in the management of diabetic retinopathy.

CONCLUSIONS

While anti-VEGF therapy is a useful tool in the management of proliferative diabetic retinopathy and diabetic macular edema, we believe physicians should avoid overreliance on anti-VEGF injections in the treatment of diabetic retinopathy. Retina specialists should be cognizant of the limitations, costs and risks of anti-VEGF monotherapy and prophylactic therapy, and of the imperative to avoid bias towards financially remunerative practice patterns when equally effective alternatives exist.

Outcomes of Baerveldt Glaucoma Drainage Devices in Pediatric Eyes

PRCIS

In children, Baerveldt implants showed 84% success at 1 year, but decreased to 32% at 8 years. Age, race, and glaucoma type were not risk factors for failure. Concurrent intraocular surgery was associated with complications.

PURPOSE

Evaluate success and risk factors for failure and complications of Baerveldt glaucoma implants in children.

METHODS

Retrospective case series of children who underwent Baerveldt implant placement (2012-2019 by single surgeon) with ≥1 year follow-up. Ocular examination and surgical details were collected. Failure defined as intraocular pressure (IOP) <5 mm Hg or >21 mm Hg for 2 consecutive visits, need for IOP related surgery, or visually significant complication.

RESULTS

One hundred-six eyes of 76 patients underwent 110 Baerveldt placement at median 6.4 years. Baerveldt placement was combined with additional procedures in 49% with vitrectomy most common (30%). Success of first Baerveldt (per patient) was 64% at final follow-up (median 4.7 y). One-, 5-, and 8-year survival rates were 84%, 60%, and 32%, respectively. There was no difference (P=0.97) in survival between first Baerveldt and all Baerveldt surgeries. Failure of first Baerveldt was not associated with sex, age, ethnicity, prior IOP-lowering surgery, concurrent intraocular surgery, or glaucoma type. Complications occurred in 14% and were associated with concurrent surgery. Twenty-six percent required additional IOP-lowering surgery. At final follow-up, IOP and glaucoma medications were significantly decreased (P<0.0001). Eyes underwent an average of 3.8±2.3 ocular surgeries and 3.0±2.0 glaucoma surgeries.

CONCLUSIONS

Baerveldt implants showed good success initially, but survival rates declined over time. No risk factors for failure of first implanted Baerveldt were identified. Concurrent surgery was associated with complications. Majority of eyes required multiple surgeries to achieve IOP control and preserve vision.

Secondary Choroidal Neovascularization in Combined Hamartoma of the Retina and Retinal Pigment Epithelium

Purpose:

To report a 4-year-old boy with a large, macula-involving combined hamartoma of the retina and retinal pigment epithelium (CHRRPE) lesion with an associated choroidal neovascular membrane involving the fovea, characterized with multimodal imaging.

Methods:

Case report.

Results:

Given the low likelihood of visual improvement with intervention, observation was recommended and the CHRRPE remained stable on follow-up 4 months after presentation.

Conclusion:

CHRRPE is a rare congenital retinal lesion that is variably pigmented. Awareness of rare complications, such as CNVM, as seen in this pediatric case is paramount.

Outcomes of combined endoscopic vitrectomy and posteriorly placed glaucoma drainage devices in pediatric patients

Background

This study aims to describe outcomes of posteriorly-placed glaucoma drainage devices (GDD) with concurrent endoscopic vitrectomy in pediatric patients with glaucoma and corneal opacification.

Methods

This retrospective case series identified patients under 18 years of age who underwent posteriorly-placed GDD implantation with concurrent endoscopic vitrectomy between 2012 and 2021. Data collected included ocular diagnoses, prior intraocular surgeries, type and position of GDD, surgical complications, and additional surgeries. Preoperative and final visual acuity, intraocular pressure (IOP), number of glaucoma medications, and exam findings were also recorded. Surgical data included type and position of GDD, Success was defined as IOP between 5-21 mmHg without visually devastating complication or need for additional glaucoma surgery.

Results

Ten patients (14 eyes) with sclerocornea (6), Peters Anomaly (4), corneal decompensation from increased IOP (3), and corneal scar (1) underwent combined endoscopic vitrectomy with posteriorly-placed GDD (Baerveldt (10 eyes), Ahmed (4 eyes)) at 4.6 ± 5.8 years of age. Four eyes of 3 patients remained successful at final follow-up, while 10 eyes of 7 patients required 2.4 ± 1.3 additional surgeries for glaucoma (7) or hypotony (3). Kaplan Meier analysis demonstrated 1- and 2-year survival rates of 36% and 18%, respectively. At final follow-up (3.7 ± 2.4 years), after an average of 4.4 ± 2.4 glaucoma surgeries, 13 of 14 eyes had obtained IOP control on significantly fewer (p<0.0001) IOP-lowering medications. Additional complications included retinal detachment (2), chronic corneal graft failure (2), phthisis (1) and band keratopathy (1).

Conclusions

Management of glaucoma in pediatric eyes with corneal opacification is challenging and often requires multiple surgeries. A combined endoscopic vitrectomy and posteriorly placed GDD is a viable technique to establish aqueous humor outflow. Although the success rate is low, this surgical approach may be useful in ultimately obtaining IOP control and preserving vision in these complex eyes.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12886-022-02373-3.

Dark-reared rd10 mice experience rapid photoreceptor degeneration with short exposure to room-light during in vivo retinal imaging

Inherited retinal diseases (IRDs) are a collection of rare genetic conditions, which can lead to complete blindness. A large number of causative genes have been identified for IRDs and while some success has been achieved with gene therapies, they are limited in scope to each individual gene and/or the specific mutation harbored by each patient with an IRD. Multiple studies are underway to elucidate common underlying mechanisms contributing to photoreceptor (PR) loss and to design gene-agnostic, pan-disease therapeutics. The rd10 mouse, which recapitulates slow degeneration of PRs, is an in vivo IRD model used commonly by vision researchers. Light deprivation by rearing animals in complete darkness significantly delays PR death in rd10 mice, subsequently increasing the time window for in vivo studies investigating neuroprotective strategies. Longitudinal in vivo retinal imaging following the same rd10 mice over time is a potential solution for reducing the number of animals required to complete a study. We describe a previously unreported phenotype in the dark-reared rd10 model that is characterized by dramatic PR degeneration following brief exposure to low-intensity light. This exquisite light sensitivity precludes the use of longitudinal studies employing in vivo imaging or other functional assessment requiring room light in rd10 mice and highlights the importance of closely following animal models of IRD to determine any deviations from the expected degeneration curve during routine experimentation.

Real-world outcomes of voretigene neparvovec treatment in pediatric patients with RPE65-associated Leber congenital amaurosis

PURPOSE

To investigate real-world safety and efficacy of voretigene neparvovec gene therapy administration in pediatric patients with biallelic RPE65 disease-causing variants.

METHODS

A retrospective study of 27 eyes of 14 patients with RPE65-associated Leber congenital amaurosis examined postoperative complications and longitudinal changes in photoreceptor function following treatment with subretinal injection of voretigene neparvovec. Full-field stimulus threshold testing (FST), Goldmann visual fields (GVF), best-corrected visual acuity (BCVA), and central subfield thickness (CST) on optical coherence tomography (OCT) scans were collected preoperatively and up to 12 months posttreatment.

RESULTS

Baseline through 6-12 month follow-up FST and GVF data were obtained for 13 eyes of 7 patients. FST improved for each eye after treatment with a mean improvement of 2.1 log-units (P < 0.001) and GVF improved for each eye with a mean improvement of 221 sum degrees (P < 0.001). BCVA improved from logMAR 0.98 at baseline to logMAR 0.83 at last follow-up (P < 0.001). Across 19 eyes of 10 patients included in CST analysis, there was a small but statistically significant 9-μ decrease in mean CST from baseline to last follow-up (P < 0.001). The most common postoperative issues included elevation in intraocular pressure (59%), persistent intraocular inflammation (15%), and vitreous opacities (26%) that resolved over a period of months.

CONCLUSIONS

This report provides some of the earliest longitudinal real-world evidence of the pediatric safety and efficacy of voretigene neparvovec using multiple functional and structural measures of the retina. Outcomes demonstrate significant improvements in visual function consistent with clinical trial results.

Perifoveal Chorioretinal Atrophy after Subretinal Voretigene Neparvovec-rzyl for RPE65-Mediated Leber Congenital Amaurosis

PURPOSE

To report an anatomic change following subretinal injection of voretigene neparvovec-rzyl (VN) for RPE65-mediated Leber congenital amaurosis.

DESIGN

Multicenter, retrospective chart review.

PARTICIPANTS

Patients who underwent subretinal VN injection at each of 4 participating institutions.

METHODS

Patients were identified as having perifoveal chorioretinal atrophy if (1) the areas of atrophy were not directly related to the touch-down site of the subretinal cannula; and (2) the area of atrophy progressively enlarged over time. Demographic data, visual acuity, refractive error, fundus photographs, OCT, visual fields, and full-field stimulus threshold (FST) were analyzed.

MAIN OUTCOME MEASURES

Outcome measures included change in visual acuity, FST, visual fields, and location of atrophy relative to subretinal bleb position.

RESULTS

A total of 18 eyes of 10 patients who underwent subretinal injection of VN were identified as having developed perifoveal chorioretinal atrophy. Eight of 10 patients (80%) developed bilateral atrophy. The mean age was 11.6 years (range, 5-20 years), and 6 patients (60%) were male. Baseline mean logarithm of the minimum angle of resolution visual acuity and FST were 0.82 (standard deviation [SD], 0.51) and -1.3 log cd.s/m² (SD, 0.44), respectively. The mean spherical equivalent was -5.7 diopters (D) (range, -11.50 to +1.75 D). Atrophy was identifiable at an average of 4.7 months (SD, 4.3) after surgery and progressively enlarged in all cases up to a mean follow-up period of 11.3 months (range, 4-18 months). Atrophy developed within and outside the area of the subretinal bleb in 10 eyes (55.5%), exclusively within the area of the bleb in 7 eyes (38.9%), and exclusively outside the bleb in 1 eye (5.5%). There was no significant change in visual acuity (P = 0.45). There was a consistent improvement in FST with a mean improvement of -3.21 log cd.s/m² (P < 0.0001). Additionally, all 13 eyes with reliable Goldmann visual fields demonstrated improvement, but 3 eyes (23.1%) demonstrated paracentral scotomas related to the atrophy.

CONCLUSIONS

A subset of patients undergoing subretinal VN injection developed progressive perifoveal chorioretinal atrophy after surgery. Further study is necessary to determine what ocular, surgical delivery, and vector-related factors predispose to this complication.

Clinical Presentation and Outcomes of Rhegmatogenous Retinal Detachments During the COVID-19 Lockdown and Its Aftermath at a Tertiary Care Center in Michigan

BACKGROUND AND OBJECTIVE

To investigate the effect of the coronavirus disease 2019 (COVID-19) lockdown on the presentation and management of acute, primary rhegmatogenous retinal detachment (RRD).

PATIENTS AND METHODS

This was a single-center, consecutive case series with historic controls, examining patients during the COVID-19 "stay-at-home" order (March 24 to June 1, 2020), the subsequent reopening phase (June 1 to July 31, 2020), and corresponding preceding intervals (March 24 to July 31, 2016 to 2019).

RESULTS

Despite a significant increase in patients presenting with macula-off RRD during the COVID-19 lockdown compared to the 2016 to 2019 timeframe (P = .03), the rate of single surgery anatomical success was similar between all groups (P = .66), as was final visual acuity (P = .61). No delays between presentation and surgical intervention were observed during the lockdown (P = .49).

CONCLUSIONS

Despite the limitations of the COVID-19 lockdown, patients underwent surgery in a timely manner and achieved comparable visual outcomes to controls before COVID-19. [Ophthalmic Surg Lasers Imaging Retina. 2021;52:593-600.].

BACILLARY LAYER DETACHMENT: MULTIMODAL IMAGING AND HISTOLOGIC EVIDENCE OF A NOVEL OPTICAL COHERENCE TOMOGRAPHY TERMINOLOGY: Literature Review and Proposed Theory

PURPOSE

To clarify the histologic basis of bacillary layer detachment (BALAD) through a review of the current literature and an analysis of retinal imaging.

METHODS

The literature for previous reports of BALAD were reviewed. An analysis of retinal images was performed to support anatomical conclusions.

RESULTS

A total of 164 unique patients with BALAD on optical coherence tomography (OCT) were identified from the published literature. Twenty-two underlying etiologies, all associated with subretinal exudation, were identified. Forty-one different OCT terminologies were found. The defining OCT feature of BALAD was a split at the level of the photoreceptor inner segment myoid creating a distinctive intraretinal cavity. Resolution of BALAD was followed by a rapid restoration of the ellipsoid zone. Histology of age-related macular degeneration eyes suggests that individual photoreceptors can shed inner segments. Furthermore, detachment of the entire layer of inner segments is a common postmortem artifact. It is proposed that BALAD occurs when outwardly directed forces promoting attachment of photoreceptor outer segments to the retinal pigment epithelium exceed the tensile strength of the photoreceptor inner segment myoid.

CONCLUSION

This review serves to strengthen the OCT nomenclature "bacillary layer detachment," based on specific reflectance information obtained by OCT and previously published histologic observations.

Role of Optical Coherence Tomography in Identifying Retinal Biomarkers in Frontotemporal Dementia: A Review

Purpose of Review

Frontotemporal dementia (FTD) is often misdiagnosed or recognized late. Clinical heterogeneity and overlap with other dementias impede accurate diagnosis. FTD biomarkers are limited, expensive, and invasive. We present a narrative review of the current literature focused on optical coherence tomography (OCT) to identify retinal biomarkers of dementia, discuss OCT findings in FTD, and explore the implications of an FTD-specific ocular biomarker for research and patient care.

Recent Findings

Recent studies suggest that outer retinal thinning detected via OCT may function as a novel ocular biomarker of FTD. The degree and rate of inner retinal thinning may correlate with disease severity and progression. In Alzheimer disease (AD), OCT demonstrates thinning of the inner retina, which may differentiate this condition from FTD. We conducted a comprehensive search of the literature and reviewed published OCT findings in FTD, AD, and mild cognitive impairment, as well as reports on biomarkers of FTD and AD used in the research and patient care settings. Three of the authors (O.M., N.S.K., and K.Z.Y.) independently conducted literature searches using PubMed to identify studies published before May 1, 2020, using the following search terminology: "Alzheimer's disease," "Alzheimer's dementia," "frontotemporal dementia," "FTD," "mild cognitive impairment," "dementia biomarkers," and "neurodegeneration biomarkers." Search results were then refined using one or more of the following keywords: "optical coherence tomography," "optical coherence tomography angiography," "retinal imaging," and "retinal thinning." The selection of published works for inclusion in this narrative review was then limited to full-text articles written in English based on consensus agreement of the authors.

Summary

FTD diagnosis is imprecise, emphasizing the need for improved state and trait biomarkers. OCT imaging of the retina holds considerable potential for establishing effective ocular biomarkers for FTD.

Toxoplasma Retinochoroiditis with Chorioretinal Neovascularization in a Young Patient

We present a pediatric case to highlight the clinical appearance and management of choroidal neovascularization in the setting of active toxoplasma retinochoroiditis (TRC). A 17-year-old female presented with 2 days of blurry vision in her left eye. Retinal examination demonstrated a pigmented chorioretinal lesion with associated subretinal fluid, vessel sheathing, and adjacent intraretinal hemorrhage. She was diagnosed with active choroidal neovascularization and successful treatment with bevacizumab revealed an underlying active toxoplasmosis lesion. Choroidal neovascularization may rarely present during an acute case of TRC. Dual therapy with anti-vascular endothelial growth factor antibody and anti-parasitic agents leads to improved visual outcomes.

Concentric Macular Rings Without Ocular Pathology

Concentric macular rings (CMRs) of Henle's fiber layer (HFL) are an uncommon imaging phenomenon previously associated with foveal hypoplasia and epiretinal membrane. Here, we present a case of a 15-year-old boy with bilateral CMRs, normal visual function, and no ocular pathology. These bilateral findings in the absence of vitreomacular traction, foveal hypoplasia, or any other ocular abnormality suggest that macular rings may occur as a normal but rare variant of HFL architecture. [Ophthalmic Surg Lasers Imaging Retina. 2021;52:353-355.].

The Diagnostic Conundrum of Retinitis and a Pigmented Scar

We report a finding of a pigmented chorioretinal scar with acute retinal necrosis (ARN) caused by herpes simplex virus 2 (HSV-2) infection rather than toxoplasma, creating an initial diagnostic dilemma. A 53-year-old functionally monocular male presented with painless floaters and blurry vision in his seeing eye over a period of 4 days. An exam demonstrated anterior chamber (AC) reaction, vitritis, multifocal patches of whitening, and an occlusive retinal vasculitis. A superior pigmented chorioretinal scar with overlying contracted vitreous was noted in the periphery with no adjacent retinal whitening. The patient was treated for both ARN and toxoplasma chorioretinitis until PCR study of the vitreous and AC returned positive for HSV-2 and negative for toxoplasmosis. Management consisted of a dual therapy regimen of both oral and intravitreal antiviral agents as well as oral corticosteroids. The patient's clinical course was complicated by rhegmatogenous retinal detachment within 2 weeks after symptom onset, requiring pars plana vitrectomy with silicone oil and intraoperative intraocular incubation with foscarnet. We review emerging evidence for pigmented chorioretinal scars in ARN specifically caused by HSV-2, as well as diagnostic and treatment dilemmas in the management of ARN and ARN detachments.

Contemporary Management of Complex and Non-Complex Rhegmatogenous Retinal Detachment Due to Giant Retinal Tears

Purpose

To investigate the clinical features and surgical outcomes of rhegmatogenous retinal detachment (RRD) associated with giant retinal tears (GRTs) at a tertiary referral center.

Patients and Methods

A retrospective, non-consecutive interventional case series of GRT-associated RRDs that underwent primary surgical repair at the University of Michigan W.K. Kellogg Eye Center between January 1, 2011 and July 1, 2020. Clinical characteristics and preoperative, perioperative, and postoperative data were collected.

Results

Forty-eight eyes of 47 patients with GRT-associated RRDs met inclusion criteria, including those that were children (under 12 years, N=4, 8.3%), associated with a history of trauma (N=20, 41.7%) or with grade C proliferative vitreoretinopathy (PVR-C) (N=7, 14.6%) at baseline. Median age was 46 years (interquartile range (IQR): 29 years, range: 4 to 72 years), median follow-up was 28 months (IQR: 43 months, range: 3-124 months), and 83.3% (N=40) of subjects were male. Primary surgical repair for GRT-associated RRDs included pars plana vitrectomy (PPV) (N=40, 83.3%), scleral buckle (SB) (N=1, 2.1%), or combined PPV/SB (N=7, 14.6%). Surgical approach commonly involved the use of perfluorocarbon liquid (N=43, 90%) and gas tamponade (N=39, 81%). Single surgery anatomic success (SSAS) was 75% (95% CI: 60%, 85%) at 3 months and 65% (95 CI: 47%, 78%) at 2 years. Final anatomic success was achieved in all 48 eyes (100%). Median visual acuity improved from 20/250 preoperatively to 20/60 at final follow-up, with 44% (N=20) of eyes achieving postoperative visual acuity of 20/40 or better.

Conclusion

In this series from a tertiary referral center, both complex and non-complex GRT-associated RRDs were most commonly managed with PPV alone, perfluorocarbon liquid, and gas tamponade with favorable final anatomic and visual outcomes comparable to other modern GRT series.

Surgical repair of primary non-complex rhegmatogenous retinal detachment in the modern era of small-gauge vitrectomy

OBJECTIVE

To report anatomic and visual outcomes of pars plana vitrectomy (PPV), as well as scleral buckling (SB) and PPV/SB as surgical treatments for the management of primary, non-complex rhegmatogenous retinal detachment (RRD).

METHODS AND ANALYSIS

Data from 751 eyes that underwent PPV, SB or combined PPV/SB as a surgical treatment for primary non-complex RRD with at least 3 months of follow-up were analysed to determine rates of single surgery anatomic success (SSAS) and final anatomic success (FAS). Patients or the public were not involved in the design, conduct or reporting of this research.

RESULTS

PPV accounted for 89.0% (n=668), PPV/SB for 6.8% (n=51) and SB for 4.2% (n=32) cases. Overall SSAS (91.2% PPV, 84.3% PPV/SB, 93.8% SB; p=0.267) and FAS (96.7% PPV, 94.1% PPV/SB and 100.0% SB; p=0.221) were reported for the three surgical groups. SSAS and FAS were similar for lens status, macular detachment status and the presence or absence of inferior retinal breaks for each of the PPV, PPV/SB and SB groups.

CONCLUSIONS

In this large, single institution, retrospective case series, we report surgical outcomes for patients with primary non-complex RRD managed with PPV, SB or PPV/SB in the modern era of small-gauge vitrectomy. We demonstrate that primary PPV without adjunct SB provides excellent anatomic and visual outcomes irrespective of lens status, macular involvement or pathology location.

Association of metformin and development of dry age-related macular degeneration in a U.S. insurance claims database

PURPOSE

To assess whether metformin is associated with dry age-related macular degeneration (dAMD) development.

METHODS

In this retrospective cohort study, patients enrolled in a nationwide U.S. medical insurance claims database from 2002 to 2016 were included if they had diabetes mellitus, were ⩾55 years old, and were enrolled for ⩾2 years without a prior AMD diagnosis. The primary exposure was metformin use analyzed as either active or prior use or cumulative metformin dosage over the study period. A time updating Cox proportional hazard regression was used to estimate the hazard ratio of dAMD incidence with metformin exposure.

RESULTS

Among 1,007,226 diabetic enrollees, 53.3% were female and 66.4% were white with a mean hemoglobin A1c of 6.8%. Of eligible enrollees, 166,115 (16.5%) were taking metformin at the index date. Over the study period, 29,818 (3.0%) participants developed dAMD. In the active versus prior use of metformin model, active use conferred an increased hazard of developing dAMD (HR, 1.08; 95% CI, 1.04-1.12) while prior use had a decreased hazard (HR, 0.95; 95% CI 0.92-0.98). The cumulative metformin dosage model showed a significant trend toward increased hazard of dAMD incidence with increasing cumulative dosage (p < 0.001), with the lowest dosage quartile having decreased hazard of dAMD incidence (HR, 0.95; 95% CI, 0.91-0.99) and the highest having increased hazard (HR, 1.07; 95% CI, 1.01-1.13).

CONCLUSIONS

Small, conflicting associations between metformin exposure and development of dAMD were observed depending on cumulative dosage and whether drug use was active, suggesting metformin did not substantially affect the development of dAMD.

Ocular Toxoplasmosis after Exposure to Wild Game

Purpose: To describe eight patients with toxoplasma retinochoroiditis following exposure to wild game.Methods: Retrospective, multicenter case seriesResults: Eight men, aged 29 to 71 (mean, 56 years), developed toxoplasmic retinochoroiditis after hunting and/or consuming wild game in the United States, including seven deer and one bear. Five patients developed the disease after eating undercooked game meat, while three developed ocular findings after cleaning hunted animals. Seven patients were healthy prior to exposure. LogMAR visual acuity at presentation was 0.697 ± 0.745, improving to 0.256 ± 0.335 by last follow-up. Disease complications developed in five (62.5%) patients, of which recurrence of retinochoroiditis was the most common.Conclusions: Contact with wild game is a potential source of primary ocular toxoplasmosis in immunocompetent adults. Hunters and consumers of rare game are at risk of serious ocular disease and appropriate contact precautions and cooking may reduce this complication.

Association of Ocular Antihypertensive Medications and the Development and Progression of Age-related Macular Degeneration in a U.S. Insurance Claims Database

Purpose/Aim: To assess whether ocular antihypertensives are associated with the development and progression of age-related macular degeneration (AMD).Materials and Methods: This retrospective, observational cohort study using healthcare claims data from a U.S. nationwide managed-care network between January 1, 2006 and December 31, 2016, included enrollees ≥40 years old with primary open-angle glaucoma with or without a diagnosis of nonexudative AMD at the index date. Hazard ratios (HR) for developing AMD or progressing from nonexudative to exudative AMD with exposure to ocular antihypertensive medications were analyzed.Results: Of 132 963 eligible enrollees, 118 174 (87.5%) had no diagnosis of AMD at baseline while 14 789 (12.5%) had adiagnosis of nonexudative AMD. Prostaglandin analog exposure had adecreased hazard of developing AMD among individuals without baseline disease (HR, 0.90; 95% CI, 0.87-0.94; p< .0001), while topical alpha₂-agonist exposure demonstrated an increased hazard of AMD development (HR, 1.08; 95% CI, 1.03-1.14; p= .004). Among patients with baseline nonexudative AMD, topical carbonic anhydrase inhibitor exposure was associated with adecreased hazard of progressing to exudative disease (HR, 0.84; 95% CI, 0.71-0.99; p= .04) while topical alpha₂-agonists had increased hazard (HR, 1.17; 95% CI, 1.01-1.36; p= .04).Conclusions: Certain ocular antihypertensive medications may be associated with development or progression of AMD. Their role in AMD pathogenesis should be better understood as they are considered for therapeutics in this disease.

Predictors of visual outcomes in pediatric open globe injuries

PURPOSE

To identify predictors of visual outcomes in children with open globe injuries.

METHODS

The medical records of patients (≤18 years of age) with open globe injury from 2012 to 2020 at a single institution were retrospectively reviewed. The Pediatric Ocular Trauma Scores (POTS) and Toddler Ocular Trauma Scores (TOTS) were assessed against our cohort. Univariate and multivariate linear regression analysis was performed to identify predictors of visual outcome.

RESULTS

A total of 85 eyes of 85 pediatric patients (63 males [74%]) were included. Median patient age was 8.9 years. Final best-corrected visual acuity was significantly associated with presenting vision (P = 0.0001), age at injury (P = 0.02), lens involvement (P < 0.0001), retinal detachment (P < 0.0001), and location of injury (P < 0.0001). In a multivariate linear regression model, only presenting visual acuity and retinal detachment were independent predictors of outcome. When visual acuity was unknown, age at injury, lens involvement, and retinal detachment were independently associated with final visual acuity. POTS and TOTS scores moderately correlated with final best-corrected visual acuity (R² = 0.51 and R² = 0.53, resp.).

CONCLUSIONS

We identified patient characteristics predicting visual outcomes in a large US-based cohort of pediatric open globe injuries. POTS and TOTS scores moderately correlated with final visual acuity; however, the small study sizes from which they were derived preclude our identifying which predictors are most important. Development of a more predictive model will require a large multicenter study population or registry.

Cryotherapy for the management of refractory hypotony secondary to post-goniotomy cyclodialysis cleft

Purpose

Observation

Conclusions

•

An unusual clinical course for a case of a post-goniotomy cyclodialysis cleft.

•

Persistent hypotony despite indirect closure of the cyclodialysis cleft.

•

The role of cryotherapy for management of post-goniotomy refractory hypotony.

Novel TMEM98, MFRP, PRSS56 variants in a large United States high hyperopia and nanophthalmos cohort

Nanophthalmos is a rare condition defined by a small, structurally normal eye with resultant high hyperopia. While six genes have been implicated in this hereditary condition (MFRP, PRSS56, MYRF, TMEM98, CRB1,VMD2/BEST1), the relative contribution of these to nanophthalmos or to less severe high hyperopia (≥ + 5.50 spherical equivalent) has not been fully elucidated. We collected probands and families (n = 56) with high hyperopia or nanophthalmos (≤ 21.0 mm axial length). Of 53 families that passed quality control, plausible genetic diagnoses were identified in 10/53 (18.8%) by high-throughput panel or pooled exome sequencing. These include 1 TMEM98 family (1.9%), 5 MFRP families (9.4%), and 4 PRSS56 families (7.5%), with 4 additional families having single allelic hits in MFRP or PRSS56 (7.5%). A novel deleterious TMEM98 variant (NM_015544.3, c.602G>C, p.(Arg201Pro)) segregated with disease in 4 affected members of a family. Multiple novel missense and frameshift variants in MFRP and PRSS56 were identified. PRSS56 families were more likely to have choroidal folds than other solved families, while MFRP families were more likely to have retinal degeneration. Together, this study defines the prevalence of nanophthalmos gene variants in high hyperopia and nanophthalmos and indicates that a large fraction of cases remain outside of single gene coding sequences.

Randomized Safety and Feasibility Trial of Ultra-Rapid Cooling Anesthesia for Intravitreal Injections

PURPOSE

To test the safety and preliminary efficacy of rapid, nonpharmacologic anesthesia via cooling for intravitreal injections.

DESIGN

Single-center, randomized phase 1 dose-ranging safety study (ClinicalTrials.gov identifier, NCT02872012).

PARTICIPANTS

Adults 18 years of age or older with a diagnosis of exudative macular degeneration or diabetic macular edema requiring bilateral anti-vascular endothelial growth factor therapy were included.

METHODS

A handheld device was developed to provide anesthesia via cooling to a focal area on the surface of the eye before intravitreal treatment (IVT). In 22 patients undergoing bilateral IVT, 1 eye was randomized to receive standard of care (SOC) lidocaine-based anesthesia and the other eye received cooling-anesthesia at 1 of 5 different temperatures and cooling times. Subjective pain was assessed via the visual analog scale (VAS; range, 1-10) at 2 time points: (1) immediately after IVT and (2) 4 hours after IVT. Treated eyes were assessed for ocular safety 24 hours after IVT.

MAIN OUTCOME MEASURES

We determined the occurrence of adverse events in eyes treated with cooling anesthesia. Mean VAS pain scores immediately after IVT and 4 hours after IVT in eyes receiving cooling anesthesia were compared with eyes receiving SOC.

RESULTS

A total of 44 eyes were treated, 22 with cooling anesthesia and 22 with SOC. No dose-related toxicity was found with cooling anesthesia. Mild, transient adverse events were recorded in 32% of patients treated with cooling anesthesia versus 44% of patients receiving SOC. The mean±standard error of the mean (SEM) VAS pain scores immediately after intravitreal injection were 2.3 ± 0.4 for patients receiving SOC and 2.2 ± 0.6 in patients receiving -10° C cooling anesthesia (P = 0.8). Mean±SEM pain scores 4 hours after injection were 1.6 ± 0.4 for SOC and 1.2 ± 0.5 in the combined -10° C arms (P = 0.56). Total mean±SEM procedure time was 124 ± 5 seconds for patients treated with cooling anesthesia versus 395 ± 40 seconds for SOC (P < 0.0001).

CONCLUSIONS

Ultra-rapid cooling of the eye for anesthesia was well tolerated, with -10° C treatment resulting in comparable levels of anesthesia to SOC with a reduction in procedure time.

Survey of Intravitreal Injection Practice Patterns Among Retina Specialists

Purpose:

Intravitreal injection therapy (IVT) is the most performed procedure in ophthalmology. This study was conducted to determine current trends in IVT delivery.

Methods:

An online, 31-question, multiple-choice survey was sent to 1677 retina specialists. The survey consisted of 3 sections: general questions, procedure technique, and postprocedure technique.

Results:

A total of 264 (16%) retina specialists completed the survey. The use of povidone-iodine (100%) and small-gauge needles (97%) was common, whereas ocular anesthesia was split among lidocaine gel (31%), lidocaine drops (25%), subconjunctival lidocaine (28%), and lidocaine-soaked pledgets (15%). More than 85% indicated povidone-iodine contributes to post-IVT corneal toxicity, and 12% reported that a needlestick injury to physician or staff occurred during IVT.

Conclusions:

Key areas for IVT improvement include optimized ocular anesthesia, development of a guarded needle for ocular drug delivery, and formulation of a less toxic ocular antiseptic.

Hexokinase 2 is dispensable for photoreceptor development but is required for survival during aging and outer retinal stress

Photoreceptor death is the ultimate cause of vision loss in many retinal degenerative conditions. Identifying novel therapeutic avenues for prolonging photoreceptor health and function has the potential to improve vision and quality of life for patients suffering from degenerative retinal disorders. Photoreceptors are metabolically unique among other neurons in that they process the majority of their glucose via aerobic glycolysis. One of the main regulators of aerobic glycolysis is hexokinase 2 (HK2). Beyond its enzymatic function of phosphorylating glucose to glucose-6-phosphate, HK2 has additional non-enzymatic roles, including the regulation of apoptotic signaling via AKT signaling. Determining the role of HK2 in photoreceptor homeostasis may identify novel signaling pathways that can be targeted with neuroprotective agents to boost photoreceptor survival during metabolic stress. Here we show that following experimental retinal detachment, p-AKT is upregulated and HK2 translocates to mitochondria. Inhibition of AKT phosphorylation in 661W photoreceptor-like cells results in translocation of mitochondrial HK2 to the cytoplasm, increased caspase activity, and decreased cell viability. Rod-photoreceptors lacking HK2 upregulate HK1 and appear to develop normally. Interestingly, we found that HK2-deficient photoreceptors are more susceptible to acute nutrient deprivation in the experimental retinal detachment model. Additionally, HK2 appears to be important for preserving photoreceptors during aging. We show that retinal glucose metabolism is largely unchanged after HK2 deletion, suggesting that the non-enzymatic role of HK2 is important for maintaining photoreceptor health. These results suggest that HK2 expression is critical for preserving photoreceptors during acute nutrient stress and aging. More specifically, p-AKT mediated translocation of HK2 to the mitochondrial surface may be critical for protecting photoreceptors from acute and chronic stress.

Advancing Clinical Trials for Inherited Retinal Diseases: Recommendations from the Second Monaciano Symposium

Major advances in the study of inherited retinal diseases (IRDs) have placed efforts to develop treatments for these blinding conditions at the forefront of the emerging field of precision medicine. As a result, the growth of clinical trials for IRDs has increased rapidly over the past decade and is expected to further accelerate as more therapeutic possibilities emerge and qualified participants are identified. Although guided by established principles, these specialized trials, requiring analysis of novel outcome measures and endpoints in small patient populations, present multiple challenges relative to study design and ethical considerations. This position paper reviews recent accomplishments and existing challenges in clinical trials for IRDs and presents a set of recommendations aimed at rapidly advancing future progress. The goal is to stimulate discussions among researchers, funding agencies, industry, and policy makers that will further the design, conduct, and analysis of clinical trials needed to accelerate the approval of effective treatments for IRDs, while promoting advocacy and ensuring patient safety.

Late-Onset Retinal Findings and Complications in Untreated Retinopathy of Prematurity

PURPOSE

To investigate late retinal findings and complications of eyes with a history of retinopathy of prematurity (ROP) that did not meet treatment criteria and did not receive treatment during infancy.

DESIGN

Retrospective, nonconsecutive, noncomparative, multicenter case series.

PARTICIPANTS

Three hundred sixty-three eyes of 186 patients.

METHODS

Data were requested from multiple providers on premature patients with a history of ROP and no treatment during infancy who demonstrated late retinal findings or complications and included age, gender, gestational age and weight, zone and stage at infancy, visual acuity, current retina vascularization status, vitreous character, presence of peripheral retinal findings such as lattice retinal tears and detachments (RDs), retinoschisis, and fluorescein findings.

MAIN OUTCOME MEASURES

Rate of RDs and factors conferring a higher risk of RDs.

RESULTS

The average age was 34.5 years (range, 7-76 years), average gestational age was 26.6 weeks (range, 23-34 weeks), and average birth weight was 875 g (range, 425-1590 g). Findings included lattice in 196 eyes (54.0%), atrophic holes in 126 eyes (34.7%), retinal tears in 111 eyes (30.6%), RDs in 140 eyes (38.6 %), tractional retinoschisis in 44 eyes (11.9%), and visible vitreous condensation ridge-like interface in 112 eyes (30.5%). Fluorescein angiography (FA) was performed in 113 eyes, of which 59 eyes (52.2%) showed leakage and 16 eyes (14.2%) showed neovascularization. Incomplete vascularization posterior to zone 3 was common (71.6% of eyes). Retinal detachments were more likely in patients with a gestational age of 29 weeks or less (P < 0.05) and in eyes with furthest vascularization to posterior zone 2 eyes compared with zone 3 eyes (P = 0.009).

CONCLUSIONS

Eyes with ROP not meeting the treatment threshold during infancy showed various late retinal findings and complications, of which RDs were the most concerning. Complications were seen in all age groups, including patients born after the Early Treatment for Retinopathy of Prematurity Study. Contributing factors to RDs included atrophic holes within peripheral avascular retina, visible vitreous condensation ridge-like interface with residual traction, and premature vitreous syneresis. We recommend regular examinations and consideration of ultra-widefield FA examinations. Prospective studies are needed to explore the frequency of complications and benefit of prophylactic treatment and if eyes treated with anti-vascular endothelial growth factor therapy are at risk of similar findings and complications.

Coats-like Exudative Vitreoretinopathy in Retinitis Pigmentosa: Ocular Manifestations and Treatment Outcomes

PURPOSE

To provide a comprehensive review of the ocular manifestations, outcomes, and genetic findings in patients with Coats-like retinitis pigmentosa (RP).

DESIGN

Multicenter, retrospective, nonconsecutive case series.

PARTICIPANTS

Patients with a diagnosis of RP demonstrating Coats-like exudative vitreoretinopathy between January 1, 2008, and October 1, 2019.

METHODS

Evaluation of ocular findings at RP diagnosis and at time of presentation of Coats-like exudative vitreoretinopathy, pedigree analysis, genetic testing, retinal imaging, and anatomic outcomes after treatment.

MAIN OUTCOME MEASURES

Visual acuity, ophthalmoscopy results, OCT results, fluorescein angiography results, and identification of genetic mutations.

RESULTS

Nine patients diagnosed with RP and demonstrating Coats-like exudative vitreoretinopathy were included. Median age at time of RP diagnosis was 8 years (range, 1-22 years), and median age at presentation of Coats-like exudative vitreoretinopathy was 18 years (range, 1-41 years). Seven patients were female, and 2 were male. The genetic cause of disease was identified in 6 patients. Three patients demonstrated Coats-like fundus findings at the time of RP diagnosis. Exudative retinal detachment (ERD) localized to the infratemporal periphery was present in all patients, with bilateral disease observed in 7 patients. In all treated patients, focal laser photocoagulation was used to treat leaking telangiectasias and to limit further ERD expansion. Cystoid macular edema refractory to carbonic anhydrase inhibitor therapy and ultimately amenable to treatment with intravitreal anti-vascular endothelial growth factor injection was observed in 4 patients.

CONCLUSIONS

Coats-like vitreoretinopathy is present in up to 5% of all RP patients. The term Coats-like RP is used colloquially to describe this disease state, which can present at the time of RP diagnosis or, more commonly, develops late during the clinical course of patients with longstanding RP. Coats-like RP is distinct from Coats disease in that exudative pathologic features occur exclusively in the setting of a coexisting RP diagnosis, is restricted to the infratemporal retina, can affect both eyes, and does not demonstrate a male gender bias. Given the risk of added vision loss posed by exudative vitreoretinopathy in patients with RP, a heightened awareness of this condition is critical in facilitating timely intervention.

Small molecule activation of metabolic enzyme pyruvate kinase muscle isozyme 2, PKM2, circumvents photoreceptor apoptosis

Photoreceptor cell death is the ultimate cause of vision loss in many retinal disorders, and there is an unmet need for neuroprotective modalities to improve photoreceptor survival. Similar to cancer cells, photoreceptors maintain pyruvate kinase muscle isoform 2 (PKM2) expression, which is a critical regulator in aerobic glycolysis. Unlike PKM1, which has constitutively high catalytic activity, PKM2 is under complex regulation. Recently, we demonstrated that genetically reprogramming photoreceptor metabolism via PKM2-to-PKM1 substitution is a promising neuroprotective strategy. Here, we explored the neuroprotective effects of pharmacologically activating PKM2 via ML-265, a small molecule activator of PKM2, during acute outer retinal stress. We found that ML-265 increased PKM2 activity in 661 W cells and in vivo in rat eyes without affecting the expression of genes involved in glucose metabolism. ML-265 treatment did, however, alter metabolic intermediates of glucose metabolism and those necessary for biosynthesis in cultured cells. Long-term exposure to ML-265 did not result in decreased photoreceptor function or survival under baseline conditions. Notably, though, ML-265-treatment did reduce entrance into the apoptotic cascade in in vitro and in vivo models of outer retinal stress. These data suggest that reprogramming metabolism via activation of PKM2 is a novel, and promising, therapeutic strategy for photoreceptor neuroprotection.

Longitudinal Examination of Fellow-Eye Vascular Anomalies in Coats' Disease With Widefield Fluorescein Angiography: A Multicenter Study

BACKGROUND AND OBJECTIVE

Retinovascular anomalies in the fellow eyes of patients with Coats' disease have been described, but the clinical significance is unknown, as well as whether these lesions progress over time.

PATIENTS AND METHODS

This is an international, multicenter, retrospective, observational cohort study of fellow-eye abnormalities on widefield fluorescein angiography in patients with Coats' disease.

RESULTS

Three hundred fifty eyes of 175 patients with Coats' disease were analyzed. A total of 33 patients (18.8%) demonstrated abnormal fellow-eye findings: 14 (42.4%) telangiectasias, 18 (54.5%) aneurysms, six (18.2%) segmental non-perfusion, six (18.2%) leakage, and two (6.0%) vascular tortuosity. All eyes were asymptomatic, and none of the lesions progressed over time. There was no association between fellow-eye findings with severity of Coats' disease (P = .16), patient age (P = .16), or presence of systemic vascular disease (P = .16).

CONCLUSIONS

The vascular abnormalities in fellow eyes of patients with Coats' disease did not progress over time. Observation is a reasonable initial management strategy. [Ophthalmic Surg Lasers Imaging Retina. 2019;50:221-227.].

Magnetic Hyperthermia in Y79 Retinoblastoma and ARPE-19 Retinal Epithelial Cells: Tumor Selective Apoptotic Activity of Iron Oxide Nanoparticle

Purpose

To evaluate selective apoptosis of Y79 retinoblastoma versus ARPE-19 retinal pigment epithelial cells by using different doses of dextran-coated iron oxide nanoparticles (DCIONs) in a magnetic hyperthermia paradigm.

Methods

Y79 and ARPE-19 cells were exposed to different concentrations of DCIONs, namely, 0.25, 0.5, 0.75, and 1 mg/ml. After 2 hours of incubation, cells were exposed to a magnetic field with a frequency of 250 kHz and an amplitude of 4 kA/m for 30 minutes to raise the cellular temperature between 42 and 46°C. Y79 and ARPE-19 cells incubated with DCION without magnetic field exposure were used as controls. Cell viability and apoptosis were assessed at 4, 24, and 72 hours after hyperthermia treatment.

Results

At 4 hours following magnetic hyperthermia, cell death for Y79 cells was 1%, 8%, 17%, and 17% for 0.25, 0.5, 0.75 and 1 mg/ml of DCION, respectively. Cell death increased to 47%, 59%, 70%, and 75% at 24 hours and 16%, 45%, 50%, and 56% at 72 hours for 0.25, 0.5, 0.75, and 1 mg/ml of DCIONs, respectively. Magnetic hyperthermia did not have any significant toxic effects on ARPE-19 cells at all DCION concentrations, and minimal baseline cytotoxicity of DCIONs on Y79 and ARPE-19 cells was observed without magnetic field activation. Gene expression profiling showed that genes involved in FAS and tumor necrosis factor alpha signaling pathways were activated in Y79 cells following hyperthermia. Caspase 3/7 activity in Y79 cells increased following treatment, consistent with the activation of caspase-mediated apoptosis and loss of cell viability by magnetic hyperthermia.

Conclusion

Magnetic hyperthermia using DCIONs selectively kills Y79 cells at 0.5 mg/ml or higher concentrations via the activation of apoptotic pathways.

Translational Relevance

Magnetic hyperthermia using DCIONs might play a role in targeted management of retinoblastoma.

Smartphone-Based, Rapid, Wide-Field Fundus Photography for Diagnosis of Pediatric Retinal Diseases

Purpose

An important, unmet clinical need is for cost-effective, reliable, easy-to-use, and portable retinal photography to evaluate preventable causes of vision loss in children. This study presents the feasibility of a novel smartphone-based retinal imaging device tailored to imaging the pediatric fundus.

Methods

Several modifications for children were made to our previous device, including a child-friendly 3D printed housing of animals, attention-grabbing targets, enhanced image stitching, and video-recording capabilities. Retinal photographs were obtained in children undergoing routine dilated eye examination. Experienced masked retina-specialist graders determined photograph quality and made diagnoses based on the images, which were compared to the treating clinician's diagnosis.

Results

Dilated fundus photographs were acquired in 43 patients with a mean age of 6.7 years. The diagnoses included retinoblastoma, Coats' disease, commotio retinae, and optic nerve hypoplasia, among others. Mean time to acquire five standard photographs totaling 90-degree field of vision was 2.3 ± 1.1 minutes. Patients rated their experience of image acquisition favorably, with a Likert score of 4.6 ± 0.8 out of 5. There was 96% agreement between image-based diagnosis and the treating clinician's diagnosis.

Conclusions

We report a handheld smartphone-based device with modifications tailored for wide-field fundus photography in pediatric patients that can rapidly acquire fundus photos while being well-tolerated.

Translational Relevance

Advances in handheld smartphone-based fundus photography devices decrease the technical barrier for image acquisition in children and may potentially increase access to ophthalmic care in communities with limited resources.