Optometrist-delivered selective laser trabeculoplasty in the HES - a training protocol and early service evaluation

Over the last decade, the delivery of glaucoma care in the UK has changed dramatically, with more non-medical ophthalmic practitioners involved in the care of glaucoma patients. Optometrists and other non-medical professionals are now involved in the delivery of laser treatments in the Hospital Eye Service (HES), but there is currently no standardised national training framework for non-medical clinicians. Moorfields Eye Hospital and UCL's Institute of Ophthalmology have developed and delivered an education and training programme for the delivery of lasers, including Selective Laser Trabeculoplasty (SLT) by non-medical ophthalmic practitioners. The training programme is based on medical education principles, is informed by previous qualitative research into the role of ophthalmic practitioners in the delivery of laser treatments and is expected to have multidisciplinary benefits for ophthalmic healthcare. Clinical audit data indicate that optometrists can deliver safe SLT treatments, adhering to local protocols.

Glaucoma: now and beyond

The glaucomas are a group of conditions leading to irreversible sight loss and characterised by progressive loss of retinal ganglion cells. Although not always elevated, intraocular pressure is the only modifiable risk factor demonstrated by large clinical trials. It remains the leading cause of irreversible blindness, but timely treatment to lower intraocular pressure is effective at slowing the rate of vision loss from glaucoma. Methods for lowering intraocular pressure include laser treatments, topical medications, and surgery. Although modern surgical innovations aim to be less invasive, many have been introduced with little supporting evidence from randomised controlled trials. Many cases remain undiagnosed until the advanced stages of disease due to the limitations of screening and poor access to opportunistic case finding. Future research aims to generate evidence for intraocular pressure-independent neuroprotective treatments, personalised treatment through genetic risk profiling, and exploration of potential advanced cellular and gene therapies.

Clinical risk stratification in glaucoma

Glaucoma is the leading cause of preventable sight loss in the United Kingdom and the provision of timely glaucoma care has been highlighted as a significant challenge in recent years. Following a recent high-profile investigation, The Healthcare Safety Investigation Branch recommended the validation of risk stratification models to safeguard the vision-related quality of life of glaucoma patients. There continues to be no nationally agreed evidence-based risk stratification model for glaucoma care across the United Kingdom. Some models have used simple measures of disease staging such as visual field mean deviation as surrogates for risk, but more refined, individualised risk stratification models should include factors related to both visual impairment and visual disability. Candidate tools should also incorporate both ocular and systemic co-morbidities, rate of disease progression, visual needs and driving status and undergo clinical refinement and validation to justify implementation. The disruption to routine glaucoma care caused by the COVID-19 pandemic has only highlighted the importance of such risk stratification models and has accelerated their development, application and evaluation. This review aims to critically appraise the available evidence underpinning current approaches for glaucoma risk stratification and to discuss how these may be applied to contemporary glaucoma care within the United Kingdom. Further research will be essential to justify and validate the utility of glaucoma risk stratification models in everyday clinical practice.

Validation of the RCOphth and UKEGS glaucoma risk stratification tool 'GLAUC-STRAT-fast'

BACKGROUND/AIMS

The aim of this study was to validate the Glaucoma Risk Stratification Tool (GLAUC-STRAT-fast) currently recommended by the Royal College of Ophthalmologists for the risk stratification of patients with glaucoma in the UK National Health Service Hospital Eye Service.

METHODS

GLAUC-STRAT fast was applied to the LiGHT trial participants by risk-stratifying the worse eye of each patient at baseline and after 3 years of treatment. Metrics of disease severity or treatment intensity used for the validation were: increased number of monitoring visits or treatment escalations; needing a trabeculectomy; a reduction of >2 dB in visual field mean deviation (VF MD) during the monitoring period; identification of rapid VF loss on total (TD) and/or pattern deviation (PD). The proportion of eyes within each baseline stratum for each of the above markers was compared against the other strata, using a χ2 test for proportions.

RESULTS

There was an association between the baseline stratification and the number of treatment escalations needed to maintain the eye-specific target intraocular pressure (p=0.001), the number of visits needed throughout the 3-year follow-up period (p=0.001), the need for trabeculectomy (p<0.001) and absolute loss of MD over the course of the monitoring period (p<0.001). The rate of VF progression was not associated with baseline risk stratification for TD or PD progression (p≥0.007, with Bonferroni correction).

CONCLUSION

The GLAUC-STRAT fast tool is a useful tool for risk stratifying eyes with ocular hypertension or open angle glaucoma. Further research is needed to confirm and validate its applicability to more advanced glaucomas and generalisability to clinical use.

TRIAL REGISTRATION NUMBER

The LiGHT trial is registered at controlled-trials.com (ISRCTN32038223).

Comparing the Effectiveness of Phacoemulsification + Endoscopic Cyclophotocoagulation Laser versus Phacoemulsification Alone for the Treatment of Primary Open Angle Glaucoma in Patients with Cataract (CONCEPT): Study Methodology

OBJECTIVE

To describe the methodology of the Comparing the Effectiveness of Phacoemulsification + Endoscopic Cyclophotocoagulation Laser and Phacoemulsification Alone for the Treatment of Primary Open Angle Glaucoma in Patients with Cataract (CONCEPT) study, a randomized controlled trial.

DESIGN

Double-masked, randomized controlled trial.

SUBJECTS, PARTICIPANTS, AND/OR CONTROLS

Participants will be recruited from 5 United Kingdom-based centers. One hundred and sixty eyes with a diagnosis of primary open-angle glaucoma and visually significant cataract will be included. Eighty eyes will be randomized to undergo cataract surgery alone and eighty to undergo cataract surgery with endoscopic cyclophotocoagulation (ECP).

METHODS

The baseline diurnal washout intraocular pressure (IOP) will be measured. The participants will be randomized to undergo cataract surgery alone or cataract surgery with ECP upon completion of uncomplicated cataract surgery. At the 1- and 2-year post surgery follow-up visits, the measurements of washout diurnal IOP will be repeated.

MAIN OUTCOME MEASURES

Diurnal washout IOP, use of glaucoma medications, and adverse events.

CONCLUSIONS

We described the methodology of the first randomized controlled trial comparing cataract surgery alone with cataract surgery combined with ECP in the context of patients with primary open-angle glaucoma and symptomatic cataract.

FINANCIAL DISCLOSURE(S)

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

Preserflo microshunt implant for the treatment of refractory uveitic glaucoma: 36-month outcomes

OBJECTIVES

To determine 36-month efficacy and safety outcomes of the PRESERFLO Microshunt implant in the treatment of refractory uveitic glaucoma.

METHODS

Consecutive patients with uncontrolled uveitic glaucoma despite maximum medical treatment received PRESERFLO Microshunt implant with mitomycin C (MMC) in a tertiary referral glaucoma practice. Efficacy and safety outcomes data were collected at month 6, 12, 24, and 36, postoperatively. The primary outcome was surgical success, defined as intraocular pressure (IOP) between 5 and 21 mmHg or > 20% reduction from baseline, and absence of criteria for surgical failure. Secondary outcomes were IOP, visual acuity (VA), use of glaucoma medical therapy, surgical complications, rate of reoperation for glaucoma.

RESULTS

21 eyes of 21 patients were included. The mean rate of success was 0.74 (95%CI 0.48-0.88), 0.68 (0.43-0.84), 0.47 (0.25-0.67), and 0.47 (0.25-0.67, at 6, 12, 24, and 36 months postoperatively, respectively. The mean IOP decreased by 30.7% (95% CI 13.7-47.7), 26.5% (95% CI 3.2-49.8), 33.5% (95% CI 21.8-45.3), and 30.1% (95% CI 7.2-52.9) from baseline at postoperative month 6, 12, 24, and 36, respectively (p < 0.001). The mean ± SD number of glaucoma medications decreased from 4.1 ± 0.9 to 0.9 ± 1.2 at the final follow up (p = 0.0005). No sight-threatening complications were reported by 36 months.

CONCLUSIONS

Three-year results of the PRESERFLO Microshunt implant demonstrated favourable efficacy and safety profile in the treatment of refractory uveitic glaucoma.

Optic Nerve Head Gene Transcription Sequelae to a Single Elevated IOP Exposure Provides Insights Into Known Responses to Chronically Elevated IOP

Purpose

To clarify the optic nerve head (ONH) gene expression responses associated with a single, axon-damaging exposure to elevated IOP in relation to the composite cellular events previously identified in models of chronically elevated IOP.

Methods

Anesthetized rats were exposed unilaterally to an 8-hour pulse-train controlled elevation of IOP (PT-CEI) at 60 mm Hg, while others received normotensive CEI at 20 mm Hg. ONH RNA was harvested at 0 hours and 1, 2, 3, 7, and 10 days after either CEI and from naïve animals. RNA sequencing was performed to analyze ONH gene expression. DAVID Bioinformatics tools were used to identify significant functional annotation clusters. Gene function was compared between PT-CEI and two models of chronic ocular hypertension from the literature.

Results

The number of significantly changed genes peaked immediately (n = 1354) after PT-CEI (0 hours). This was followed by a lull (<4 genes per time point) at 1 and 2 days after PT-CEI. Gene activity increased again at 3 days (136 genes) and persisted at 7 (78 genes) and 10 (339 genes) days. Significant gene functional categories included an immediate upregulation of Defense Response at 0 hours, followed by upregulation in Cell Cycle, a reduction in Axonal-related genes at 3 to 10 days, and upregulation of Immune Response-related genes at 10 days following PT-CEI. The most commonly upregulated gene expression across our PT-CEI study and two chronic models of ocular hypertension were cell cycle related.

Conclusions

The PT-CEI model places in sequence ONH gene expression responses previously reported in models with chronically elevated IOP and may provide insights into their role in optic nerve damage.

Cell-Based Therapies for Glaucoma

Glaucomatous optic neuropathy (GON) is the major cause of irreversible visual loss worldwide and can result from a range of disease etiologies. The defining features of GON are retinal ganglion cell (RGC) degeneration and characteristic cupping of the optic nerve head (ONH) due to tissue remodeling, while intraocular pressure remains the only modifiable GON risk factor currently targeted by approved clinical treatment strategies. Efforts to understand the mechanisms that allow species such as the zebrafish to regenerate their retinal cells have greatly increased our understanding of regenerative signaling pathways. However, proper integration within the retina and projection to the brain by the newly regenerated neuronal cells remain major hurdles. Meanwhile, a range of methods for in vitro differentiation have been developed to derive retinal cells from a variety of cell sources, including embryonic and induced pluripotent stem cells. More recently, there has been growing interest in the implantation of glial cells as well as cell-derived products, including neurotrophins, microRNA, and extracellular vesicles, to provide functional support to vulnerable structures such as RGC axons and the ONH. These approaches offer the advantage of not relying upon the replacement of degenerated cells and potentially targeting earlier stages of disease pathogenesis. In order to translate these techniques into clinical practice, appropriate cell sourcing, robust differentiation protocols, and accurate implantation methods are crucial to the success of cell-based therapy in glaucoma. Translational Relevance: Cell-based therapies for glaucoma currently under active development include the induction of endogenous regeneration, implantation of exogenously derived retinal cells, and utilization of cell-derived products to provide functional support.

Effect of trabeculectomy on the rate of progression of visual field damage

OBJECTIVES

This study quantifies the effect of trabeculectomy on the rate of progression (RoP) of visual field (VF) damage utilising pre- and post-operative visual function as the outcome instead of surrogate outcomes of success.

METHODS

Clinical and VF data from 199 sequential patients who underwent trabeculectomy between 2015 and 2016 were extracted from the network of sites of Moorfields Eye Hospital NHS Foundation Trust. Of these, we analysed 80 eyes of 74 patients who met our inclusion criteria of at least three reliable VFs before and after surgery (false positive rate <15%). The change in mean RoP (dB/year) was tested using point-wise sensitivity values through a mixed effect model with random effects on both intercepts and slopes. A broken-stick regression of sensitivity over time, with a breakpoint at the day of surgery, modelled the individual change in RoP.

RESULTS

We analysed 10 [9,12] VFs per subject (Median [Interquartile Range]). At surgery, the age was 67 [57, 72] years, mean deviation was -10.84 [-14.7, -5.6] dB and the IOP was 18 [15, 20] mmHg. One year after surgery, the IOP was 10 [8,13] mmHg (p = 0.002). Mean RoP before surgery was -0.94 [-1.20, -0.69] dB/year (Mean [95% credible intervals]) and it was slowed down by 0.62 [0.26, 0.97] dB/year (p < 0.001) after surgery.

CONCLUSIONS

Trabeculectomy leads to a significant reduction in the RoP of VF loss postoperatively.

Design and Conduct of Randomized Clinical Trials Evaluating Surgical Innovations in Ophthalmology: A Systematic Review

PURPOSE

Surgical innovations are necessary to improve patient care. After an initial exploratory phase, novel surgical technique should be compared with alternative options or standard care in randomized controlled trials (RCTs). However, surgical RCTs have unique methodological challenges. Our study sought to investigate key aspects of the design, conduct, and reporting of RCTs of novel surgeries.

DESIGN

Systematic review.

METHODS

The protocol was prospectively registered in PROSPERO (CRD42021253297). RCTs evaluating novel surgeries for cataract, vitreoretinal, glaucoma, and corneal diseases were included. Medline, EMBASE, Cochrane Library, and Clinicaltrials.gov were searched. The search period was January 1, 2016, to June 16, 2021.

RESULTS

A total of 52 ophthalmic surgery RCTs were identified in the fields of glaucoma (n = 12), vitreoretinal surgery (n = 5), cataract (n = 19), and cornea (n = 16). A description defining the surgeon's experience or level of expertise was reported in 30 RCTs (57%) and was presented in both control and intervention groups in 11 (21%). Specification of the number of cases performed in the particular surgical innovation being assessed prior to the trial was reported in 10 RCTs (19%) and an evaluation of quality of the surgical intervention in 7 (13%). Prospective trial registration was recorded in 12 RCTs (23%) and retrospective registration in 13 (25%); and there was no registration record in the remaining 28 (53%) studies.

CONCLUSIONS

Important aspects of the study design such as the surgical learning curve, surgeon's previous experience, quality assurance, and trial registration details were often missing in novel ophthalmic surgical procedures. The Idea, Development, Exploration, Assessment, Long-term follow-up (IDEAL) framework aims to improve the quality of study design.

Glaucoma Drainage Device surgery outcomes in children with uveitic glaucoma

PURPOSE

To evaluate outcomes of glaucoma drainage device (GDD) implantation children with uveitic glaucoma.

DESIGN

Retrospective interventional case series METHODS: : Success defined as IOP ≥5 and ≤21 mmHg. Failure defined at final follow up when IOP was outside the success criteria, visual function was NPL or further glaucoma surgery (excluding removal of intraluminal stent suture or needling).

RESULTS

50 eyes of 36 children with uveitic glaucoma underwent GDD implantation. Mean age at surgery was 10.1±3.1 years (range 5-17) with a mean follow-up of 113±61 months, (range 8-228). Mean cumulative probabilities of success (95% CI) were 0.98 (0.86 - 1.00) at 1 year, 0.87 (0.73-0.94) at 5 years and 0.59 (0.32-0.78) at 15 years. 14 tubes were classified as failed, with 12 due to uncontrolled IOP (11 eyes required a second GDD), 1 eye removal of the tube due to plate exposure, and 1 eye lost light perception. Post-operative complications occurred in 36% of patients and included hypotony (22%), tube exposure (6%), tube obstruction (4%), corneal decompensation (2%) and cystoid macular edema (2%). Visual acuity remained stable (pre-op 0.35±0.42 vs. post-op 0.45±0.67, p=0.49). IOP was significantly reduced from 31.4±7.5mmHg to 14.4±5.1mmHg (p<0.0001) as were the number of glaucoma medications 3.5±1.0 vs. 1.1±1.3 (p<0.0001).

CONCLUSIONS

Refractory pediatric uveitic glaucoma can be treated successfully by GDD implantation. Further interventions to manage consequences of glaucoma or the underlying disease are common and visual function is maintained in the majority of cases.

Expansion of patient eligibility for virtual glaucoma clinics: a long-term strategy to increase the capacity of high-quality glaucoma care

AIMS

The virtual glaucoma clinic (VGC) is a well-established diagnostic pathway for delivery of glaucoma care. Current UK national guidance recommends VGCs for patients with ocular hypertension, glaucoma suspects or early glaucoma. This study evaluates whether expanded eligibility criteria, including other glaucoma phenotypes and disease stages, can deliver safe and effective care with a positive patient experience.

METHODS

Records of over 8000 patients were reviewed in order to determine suitability for VGC attendance using expanded eligibility criteria. Patients with three prior consecutive visits within the glaucoma service were included. Follow-up interval, clinic type, visual acuity (VA), intraocular pressure (IOP) and visual field performance were recorded. Patient satisfaction was recorded for a sample of 118 patients.

RESULTS

2017 patients over 31 months were included. Two-thirds of eyes had ocular comorbidities, a fifth of eyes had undergone prior cataract surgery and 10% of eyes had undergone a prior laser treatment for glaucoma. After three visits, 32% of patients remained in the VGC, 42% were seen in face-to-face clinics and 25% were discharged. There were no clinically significant changes in VA, IOP and visual field performance during follow-up. 72% of patients expressed a preference to continue their care within VGCs.

CONCLUSIONS

This study demonstrates that VGCs with expanded patient eligibility criteria can deliver high-quality glaucoma care that is safe, effective and with high levels of patient satisfaction. This approach provides a long-term solution to adapt delivery of glaucoma care to our expanding and ageing population.

An in vivo CRISPR base editing therapy to inactivate the ANGPTL3 gene: nomination of a development candidate for VERVE-201

Background

Lowering cumulative exposure to low-density lipoprotein cholesterol (LDL-C) is the primary treatment for patients with homozygous familial hypercholesterolemia (HoFH) and established atherosclerotic cardiovascular disease. Due to access, adherence, and healthcare infrastructure limitations, an important fraction of such patients fail to achieve adequate lowering of LDL-C. Durable inactivation in the liver of a cholesterol-raising gene with a one-time therapy offers potential to address this unmet need.

Purpose

Both human genetic and pharmacologic studies have validated inactivation of the angiopoietin-like protein 3 gene (ANGPTL3) as an approach to lower LDL-C and triglyceride levels, particularly when ANGPTL3 reductions &gt;80% can be achieved. Here, we outline a series of preclinical activities to optimize “VERVE-201”, a CRISPR base editing therapy targeting ANGPTL3.

Methods

Preclinical development efforts prioritized: (i) identification of a DNA site where editing of a single base pair inactivates ANGPTL3; and (ii) selection of a guide RNA and adenine base editor combination that precisely and specifically inactivates ANGPTL3; and (iii) a delivery approach suitable for all patients, including those with HoFH who lack sufficient low-density lipoprotein receptors (LDLR) needed for hepatic uptake of traditional lipid nanoparticles.

Results

Bioinformatic and in vitro screening of target sites in the ANGPTL3 gene identified a location where a single A•T to G•C DNA base pair edit leads to disruption of a splice donor and read through into a premature stop codon. To maximize editing of the ANGPTL3 gene while minimizing “off-target” editing elsewhere in the genome, &gt;200 rationally engineered and chemically modified base editing and gRNA configurations were evaluated. Lead candidates were evaluated in primary human hepatocytes to quantify ANGPTL3 editing as well as any “off-target” editing at &gt;600 candidate sites. In a cynomolgus monkey non-human primate model, a single dose of a drug product precursor that used a lipid nanoparticle delivery mechanism achieved potent and durable effects, with a 96% decrease from baseline in circulating ANGPTL3 616 days following administration. The non-human primate homologue to VERVE-201 (“VERVE-201cyno”) incorporates a GalNAc targeting ligand into the lipid nanoparticle, which bypasses LDLR to enable uptake via the liver-specific asialoglycoprotein receptor. VERVE-201cyno led to robust suppression of circulating ANGPTL3 in both a non-human primate model of HoFH and wild-type monkeys, with an average reduction of 89% and 88% respectively 90 days following administration.

Conclusions

These preclinical data provide the scientific foundation for nomination of a development candidate for VERVE-201, a “once-and-done” gene editing therapy intended to precisely, potently, and durably inactivate hepatic ANGPTL3 and thereby lower LDL-C and triglyceride concentrations permanently.

Funding Acknowledgement

Type of funding sources: Private company. Main funding source(s): Verve Therapeutics

Minimally Invasive Glaucoma Surgical Techniques for Open-Angle Glaucoma: An Overview of Cochrane Systematic Reviews and Network Meta-analysis

IMPORTANCE

Glaucoma affects more than 75 million people worldwide. Intraocular pressure (IOP)-lowering surgery is an important treatment for this disease. Interest in reducing surgical morbidity has led to the introduction of minimally invasive glaucoma surgeries (MIGS). Understanding the comparative effectiveness and safety of MIGS is necessary for clinicians and patients.

OBJECTIVE

To summarize data from randomized clinical trials of MIGS for open-angle glaucoma, which were evaluated in a suite of Cochrane reviews.

DATA SOURCES

The Cochrane Database of Systematic Reviews including studies published before June 1, 2021.

STUDY SELECTION

Reviews of randomized clinical trials comparing MIGS with cataract extraction alone, other MIGS, traditional glaucoma surgery, laser trabeculoplasty, or medical therapy.

DATA EXTRACTION AND SYNTHESIS

Data were extracted according to Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines by one investigator and confirmed by a second. Methodologic rigor was assessed using the AMSTAR 2 appraisal tool and random-effects network meta-analyses were conducted.

MAIN OUTCOMES AND MEASURES

The proportion of participants who did not need to use medication to reduce intraocular pressure (IOP) postsurgery (drop-free). Outcomes were analyzed at short-term (<6 months), medium-term (6-18 months), and long-term (>18 months) follow-up.

RESULTS

Six eligible Cochrane reviews were identified discussing trabecular bypass with iStent or Hydrus microstents, ab interno trabeculotomy with Trabectome, subconjunctival and supraciliary drainage devices, and endoscopic cyclophotocoagulation. Moderate certainty evidence indicated that adding a Hydrus safely improved the likelihood of drop-free glaucoma control at medium-term (relative risk [RR], 1.6; 95% CI, 1.4 to 1.8) and long-term (RR, 1.6; 95% CI, 1.4 to 1.9) follow-up and conferred 2.0-mm Hg (95% CI, -2.7 to -1.3 mm Hg) greater IOP reduction at long-term follow-up, compared with cataract surgery alone. Adding an iStent also safely improved drop-free disease control compared with cataract surgery alone (RR, 1.4; 95% CI, 1.2 to 1.6), but the short-term IOP-lowering effect of the iStent was not sustained. Addition of a CyPass microstent improved drop-free glaucoma control compared with cataract surgery alone (RR, 1.3; 95% CI, 1.1 to 1.5) but was associated with an increased risk of vraision loss. Network meta-analyses supported the direction and magnitude of these results.

CONCLUSIONS AND RELEVANCE

Based on data synthesized in Cochrane reviews, some MIGS may afford patients with glaucoma greater drop-free disease control than cataract surgery alone. Among the products currently available, randomized clinical trial data associate the Hydrus with greater drop-free glaucoma control and IOP lowering than the iStent; however, these effect sizes were small.

Managing risk in the face of adversity: design and outcomes of rapid glaucoma assessment clinics during a pandemic recovery

Background

The provision of timely care to the high volume of glaucoma patients stratified as “low risk” following pandemic-related appointment deferrals continues to prove challenging for glaucoma specialists. It is unknown whether stratification as “low risk” remains valid over time, raising the potential risk of harm during this period if left unmonitored. This study aimed to evaluate whether Rapid Glaucoma Assessment Clinics (RGACs) are an effective method of assessing “low-risk” patients in order to identify those who may need an escalation of care, therefore reducing the risk of the future incidents of preventable vision loss.

Methods

RGACs were developed which comprised a brief advance telephone history by a clinician and then ophthalmic technician-measured visual acuity and intraocular pressure in clinic. We report outcomes from the first month of operation describing attendance patterns, the proportion of patients from this “low risk” cohort requiring escalation and underlying reasons for treatment escalations.

Results

639 patients were invited to attend RGACs. 75% attended their booked appointment. Pre-attendance telephone consultations were associated with lower non-attendance rates (13.9% vs 29.3%, p < 0.00001). 15% of patients were no longer deemed to remain at “low risk” with further expedited clinical review scheduled. 10.4% of patients required an escalation in treatment following review.

Conclusions

RGACs are an effective approach to deliver high throughput clinical assessments for large numbers of “low-risk” glaucoma patients with deferred appointments. They enable the rapid identification and treatment of patients who would otherwise face significantly delayed review reducing the risk of future preventable vision loss.

Adjunctive modulation of wound healing during cataract surgery to promote survival of a previous trabeculectomy

BACKGROUND

Trabeculectomy is a surgical treatment for glaucoma to lower intraocular pressure with high success rates; however, it is often associated with an increased rate of cataract formation. Cataract can cause symptoms such as glare in bright conditions, foggy vision, and difficulty in driving at night. Cataract extraction surgery is highly successful in improving vision, but it comes at a cost of trabeculectomy failure, with a reported risk of 30% to 40%. An additional intervention to promote trabeculectomy survival after cataract extraction is needed. This review encompassed all adjunctive therapies used at the time of cataract surgery to increase trabeculectomy survival rate.

OBJECTIVES

To investigate the effect of the adjunctive modulation of wound healing during cataract surgery on the survival of a previously functioning trabeculectomy.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL; which contains the Cochrane Eyes and Vision Trials Register; 2021, Issue 4); Ovid MEDLINE; Ovid Embase; the ISRCTN registry; ClinicalTrials.gov; and the WHO ICTRP. We did not use any date or language restrictions in the electronic searches for trials. We last searched the electronic databases on 14 April 2021.

SELECTION CRITERIA

We planned to include all randomised controlled trials (RCTs) of participants who had a functioning trabeculectomy and were undergoing cataract surgery that compared any adjunctive therapy intended to modulate wound healing (such as 5-fluorouracil, mitomycin C, or anti-vascular endothelial growth factor (VEGF) therapy) with no adjuvant therapy.  DATA COLLECTION AND ANALYSIS: We used standard methods expected by Cochrane. Our primary outcome was trabeculectomy failure at 6 months and 12 months after cataract surgery. Secondary outcomes were mean intraocular pressure difference from pre-cataract surgery baseline to 6 to 18 months post-cataract surgery; number of medications required to control eye pressure compared to before cataract surgery; bleb appearance as measured by a summation score of the Moorfields bleb grading system or other equivalent numerical grading systems; visual field progression measured by difference in mean deviation from baseline; and any complications.

MAIN RESULTS

We did not identify any RCTs of adjunctive modulation of wound healing during cataract surgery to promote survival of a previous trabeculectomy.

AUTHORS' CONCLUSIONS

There is a need for an RCT to investigate the role of adjuvant wound modulating therapy at the time of cataract surgery to promote survival of a functioning trabeculectomy.

Ab interno supraciliary microstent surgery for open-angle glaucoma

BACKGROUND

Glaucoma is the leading cause of global irreversible blindness, often associated with raised intraocular pressure (IOP). Where medical or laser treatment has failed or is not tolerated, surgery is often required. Minimally-invasive surgical approaches have been developed in recent years to reduce IOP with lower surgical risks. Supraciliary microstent surgery for the treatment of open-angle glaucoma (OAG) is one such approach.

OBJECTIVES

To evaluate the efficacy and safety of supraciliary microstent surgery for the treatment of OAG, and to compare with standard medical, laser or surgical treatments.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL; which contains the Cochrane Eyes and Vision Trials Register; 2020, Issue 8); Ovid MEDLINE; Ovid Embase; the ISRCTN registry; ClinicalTrials.gov and the WHO ICTRP. The date of the search was 27 August 2020.

SELECTION CRITERIA

We searched for randomised controlled trials (RCTs) of supraciliary microstent surgery, alone or with cataract surgery, compared to other surgical treatments (cataract surgery alone, other minimally invasive glaucoma device techniques, trabeculectomy), laser treatment or medical treatment.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened titles and abstracts from the database search to identify studies that met the selection criteria. Data extraction, analysis, and evaluation of risk of bias from selected studies was performed independently and according to standard Cochrane methodology.

MAIN RESULTS

One study met the inclusion criteria of this review, evaluating the efficacy and safety of the Cypass supraciliary microstent surgery for the treatment of OAG, comparing phacoemulsification + supraciliary microstent surgery with phacoemulsification alone over 24 months. This study comprised 505 eyes of 505 participants with both OAG and cataract, 374 randomised to the phacoemulsification + microstent group.  In this study, the perceived risk of bias from random sequence generation, allocation concealment and selective reporting was low. However, we considered the study to be at high risk of performance bias as surgeons/investigators were unmasked. Attrition bias was unclear, with 448/505 participants contributing to per protocol analysis. Insertion of a Cypass supraciliary microstent combined with phacoemulsification probably increases the proportion of participants who are medication-free (not using eye-drops) at 24 months compared with phacoemulsification alone (85% versus 59%, risk ratio (RR) 1.27, 95% confidence interval (CI) 1.09 to 1.49, moderate-certainty evidence). There is high-certainty evidence that a greater improvement in mean IOP occurs in the phacoemulsification + microstent group - mean (SD) change in IOP from baseline of -5.4 (3.9) mmHg in the phacoemulsification group, compared to -7.4 (4.4) mmHg in the phacoemulsification + microstent group at 24 months (mean difference -2.0 mmHg, 95% CI -2.85 to -1.15). There is moderate-certainty evidence that insertion of a microstent is probably associated with a greater reduction in use of IOP-lowering drops (mean reduction of 0.7 medications in the phacoemulsification group, compared to a mean reduction of 1.2 medications in the phacoemulsification + microstent group). Insertion of a microstent during phacoemulsification may reduce the requirement for further glaucoma intervention to control IOP at a later stage compared to phacoemulsification alone (RR 0.26, 95% CI 0.07 to 1.04, low-certainty evidence). There is no evidence relating to the rate of visual field progression, or proportion of participants whose visual field loss progressed in this study. There is moderate-certainty evidence showing little or no difference in the proportion of participants experiencing postoperative complications over 24 months between participants in the microstent group compared to those who received phacoemulsification alone (RR 1.1, 95% CI 0.8 to 1.4). Five year post-approval data regarding the safety of the Cypass supraciliary microstent showed increased endothelial cell loss, associated with the position of the microstent in the anterior chamber. There were no reported health-related quality of life (HRQoL) outcomes in the included study.

AUTHORS' CONCLUSIONS

Data from this single RCT show superiority of supraciliary microstent surgery when combined with phacoemulsification compared to phacoemulsification alone in achieving medication-free control of OAG. However, there are long-term safety concerns with the device used in this trial, relating to the observed significant loss of corneal endothelial cells at five years following device implantation. At the time of this review, this device has been withdrawn from the market. This review has found that few high-quality studies exist comparing supraciliary microstent surgery to standard medical, laser or surgical glaucoma treatments. This should be addressed by further appropriately designed RCTs with sufficient long-term follow-up to ensure robust safety data are obtained. Consideration of health-related quality of life outcomes should also feature in trial design.

Strain Specific Responses in a Microbead Rat Model of Experimental Glaucoma

PURPOSE

A major challenge in glaucoma research is the lack of reproducible animal models of RGC and optic nerve damage, the characteristic features of this condition. We therefore examined the glaucomatous responses of two different rat strains, the Brown Norway (BN) and Lister Hooded (LH) rats, to high intraocular pressure (IOP) induced by injection of magnetic beads into the anterior chamber.

METHODS

Magnetic microsphere suspensions (20 µl of 5-20 mg/ml) were injected into the anterior chamber of BN (n = 9) or LH (N = 15) rats. Animals from each strain were divided into three groups, each receiving a different dose of microspheres. IOP was measured over 4 weeks using a rebound tonometer. Retinal ganglion cell (RGC) damage and function were assessed using scotopic electroretinograms (ERGs), retinal flatmounts and optic nerve histology. ANOVA and Student's t-tests were used to analyse the data.

RESULTS

A significant elevation in IOP was observed in BN rats receiving injections of 20 mg (37.18 ± 12.28 mmHg) or 10 mg microspheres/ml (36.95 ± 13.63 mmHg) when compared with controls (19.63 ± 4.29 mmHg) (p < .001) over 2 weeks. This correlated with a significant impairment of RGC function, as determined by scotopic ERG (p < .001), reduction in axon number (p < .05) and lower RGC density (P < .05) in animals receiving 20 mg or 10 mg microspheres/ml as compared with controls. LH rats receiving similar microsphere doses showed reduced scotopic ERG function (p < .001) after 2 weeks. No changes in IOP was seen in this strain, although a reduction in axon density was observed in optic nerve cross-sections (p < .05). Initial changes in IOP and ERG responses observed in BN rats remained unchanged for a duration of 7 weeks. In LH animals, ERG responses were decreased at 1-2 weeks and returned to control levels after 5 weeks.

CONCLUSIONS

Although this model was easily reproducible in BN rats, the phenotype of injury observed in LH rats was very different from that observed in BN animals. We suggest that differences in the glaucomatous response observed in these two strains may be ascribed to anatomical and physiological differences and merits further investigation.

Intraocular pressure reduction in glaucoma: Does every mmHg count?

The reduction of intraocular pressure is currently the only known modifiable risk factor for the treatment of Glaucoma, which is the leading cause of irreversible worldwide blindness. This concise review discusses the evidence underpinning the reduction of intraocular pressure in the treatment of glaucoma, the role of target intraocular pressure in clinical practice and appraises clinical data supporting the concept that every mmHg of intraocular pressure reduction is important in reducing the risk of developing glaucoma and the progression of existing disease. Every mmHg in IOP reduction is important, with evidence showing an impact on both functional and structural progression but does not however explain all glaucoma risk.

Comprehensive Ocular Examination of Healthy Newborns in the Middle East

Purpose: To report the prevalence of the perinatal ocular disease in healthy infants referred to a referral eye centre in the Middle East region for comprehensive ocular examinations.Methods: All healthy full-term babies born at a tertiary care women's and children hospital were referred to Moorfields Eye Hospital Centre in Abu Dhabi (MEHCAD), the United Arab Emirates for comprehensive ocular examination between January 2018 and April 2019. The examination included red-reflex testing, external, anterior and dilated posterior segment examination, and refraction.Results: Out of 6836 newborns, 4719 (69%) were not referred due to lack of national insurance (n = 3089), out of network referral (n = 1405), required ROP screening (n = 220) and identification of systemic diagnosis (n = 5). Of 2117 eligible referrals 897 (42%) babies were not examined because they either did not attend (890) or had a double booking for ROP screening (7); hence, 1220 babies (56%) were examined. Their mean age was 39 ± 16 days, and 48.8% were male, 51.2% were female. One hundred and sixty-four (13.4%) babies had an ocular abnormality in 249 (10.2%) eyes. The commonest abnormalities were nasolacrimal duct obstruction (36%) and refractive errors in 53 patients (32.3%). Congenital cataract and ptosis were present in four (0.3%) and three (0.2%) babies, respectively. The commonest retinal findings were intra-retinal haemorrhages (1.4%). Other posterior pole abnormalities included optic disc pit (0.08%) and myelinated nerve fibers (0.08%). One eye (0.08%) had a congenital macular hole.Conclusion: Comprehensive ocular examinations of healthy infants identifies a number of ocular abnormalities that would not be detected using red-reflex testing by a paediatrician or nurse.

Artificial Intelligence Algorithms to Diagnose Glaucoma and Detect Glaucoma Progression: Translation to Clinical Practice

Purpose

This concise review aims to explore the potential for the clinical implementation of artificial intelligence (AI) strategies for detecting glaucoma and monitoring glaucoma progression.

Methods

Nonsystematic literature review using the search combinations “Artificial Intelligence,” “Deep Learning,” “Machine Learning,” “Neural Networks,” “Bayesian Networks,” “Glaucoma Diagnosis,” and “Glaucoma Progression.” Information on sensitivity and specificity regarding glaucoma diagnosis and progression analysis as well as methodological details were extracted.

Results

Numerous AI strategies provide promising levels of specificity and sensitivity for structural (e.g. optical coherence tomography [OCT] imaging, fundus photography) and functional (visual field [VF] testing) test modalities used for the detection of glaucoma. Area under receiver operating curve (AROC) values of > 0.90 were achieved with every modality. Combining structural and functional inputs has been shown to even more improve the diagnostic ability. Regarding glaucoma progression, AI strategies can detect progression earlier than conventional methods or potentially from one single VF test.

Conclusions

AI algorithms applied to fundus photographs for screening purposes may provide good results using a simple and widely accessible test. However, for patients who are likely to have glaucoma more sophisticated methods should be used including data from OCT and perimetry. Outputs may serve as an adjunct to assist clinical decision making, whereas also enhancing the efficiency, productivity, and quality of the delivery of glaucoma care. Patients with diagnosed glaucoma may benefit from future algorithms to evaluate their risk of progression. Challenges are yet to be overcome, including the external validity of AI strategies, a move from a “black box” toward “explainable AI,” and likely regulatory hurdles. However, it is clear that AI can enhance the role of specialist clinicians and will inevitably shape the future of the delivery of glaucoma care to the next generation.

Translational Relevance

The promising levels of diagnostic accuracy reported by AI strategies across the modalities used in clinical practice for glaucoma detection can pave the way for the development of reliable models appropriate for their translation into clinical practice. Future incorporation of AI into healthcare models may help address the current limitations of access and timely management of patients with glaucoma across the world.

Visual Field Outcomes from the Multicenter, Randomized Controlled Laser in Glaucoma and Ocular Hypertension Trial (LiGHT)

PURPOSE

To compare visual field outcomes of ocular hypertensive and glaucoma patients treated first with medical therapy with those treated first with selective laser trabeculoplasty (SLT).

DESIGN

Secondary analysis of patients from the Laser in Glaucoma and Ocular Hypertension study, a multicenter randomized controlled trial.

PARTICIPANTS

Three hundred forty-four patients (588 eyes) treated first with medical therapy and 344 patients (590 eyes) treated first with SLT.

METHODS

Visual fields (VFs) were measured using standard automated perimetry and arranged in series (median length and duration, 9 VFs over 48 months). Hierarchical linear models were used to estimate pointwise VF progression rates, which were then averaged to produce a global progression estimate for each eye. Proportions of points and patients in each treatment group with fast (<-1 dB/year) or moderate (<-0.5 dB/year) progression were compared using log-binomial regression.

MAIN OUTCOME MEASURES

Pointwise and global progression rates of total deviation (TD) and pattern deviation (PD).

RESULTS

A greater proportion of eyes underwent moderate or fast TD progression in the medical therapy group compared with the SLT group (26.2% vs. 16.9%; risk ratio [RR], 1.55; 95% confidence interval [CI], 1.23-1.93; P < 0.001). A similar pattern was observed for pointwise rates (medical therapy, 26.1% vs. SLT, 19.0%; RR, 1.37; 95% CI, 1.33-1.42; P < 0.001). A greater proportion of pointwise PD rates were categorized as moderate or fast in the medical therapy group (medical therapy, 11.5% vs. SLT, 8.3%; RR, 1.39; 95% CI, 1.32-1.46; P < 0.001). No statistical difference was found in the proportion of eyes that underwent moderate or fast PD progression (medical therapy, 9.9% vs. SLT, 7.1%; RR, 1.39; 95% CI, 0.95, 2.03; P = 0.0928).

CONCLUSIONS

A slightly larger proportion of ocular hypertensive and glaucoma patients treated first with medical therapy underwent rapid VF progression compared with those treated first with SLT.

Individualizing Therapy for Neovascular Age-Related Macular Degeneration with Aflibercept (VITAL): A Two-Year Prospective, Interventional Single-Centre Trial

AIMS

To report the mean change in Early Treatment Diabetic Retinopathy Study (ETDRS) best-corrected visual acuity (BCVA) and reading performance (reading acuity and maximum reading speed (MRS) using the MNREAD test) between baseline and 24 months in treatment-naïve patients with neovascular age-related macular degeneration (nAMD) treated with intravitreal aflibercept injections.

METHODS

A prospective, open-label, interventional non-randomised case series with 24 months' duration. Patients were recruited to the study from medical retina clinics at Moorfields Eye Hospital. Intravitreal injections of 2.0 mg aflibercept in the study eye were administered using a fixed dosing regimen during the first year and a treat-and-extend treatment regimen during the second year of treatment.

RESULTS

Fifty patients were enrolled with a mean age (SD) of 78.7 (7.6) years; a mean BCVA of 62.8 ETDRS letters; mean reading acuity of 0.52 logMAR; mean maximum reading speed (MRS) of 141.3 words per minute and a central macular thickness of 322.6 µm at baseline. The mean improvement in BCVA was 6.4 letters for the 44 patients (88%) for whom data was available at 2 years. The mean improvement in reading acuity was 0.13 logMAR with an improvement in MRS of 2.9 words per minute. The mean reduction in CRT from baseline was 104.8 µm.

CONCLUSIONS

Aflibercept treatment of nAMD using fixed dosing in year 1 and treat and extend in year 2 leads to improvements in reading ability, visual acuity and retinal morphology which were maintained to 2 years of treatment.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier NCT02441816, the VITAL study.

Recent trends in vision impairment certifications in England and Wales

BACKGROUND

The Certificate of Visual Impairment (CVI) provides essential data for preventable sight loss indicators as part of the Public Health Outcomes Framework (PHOF) published annually by the Department of Health. Trends in CVI certification rates can provide information on the effectiveness of current services and treatments and may be used to guide allocation of resources, and is the only such indicator within ophthalmology. This study aimed to compare recent trends in new vision impairment certifications in 2017/18 against prior baseline data in England and document trends in new certifications in Wales.

METHODS

PHOF data from 2010/11 and 2017/18 were examined with respect to preventable sight loss indicators: age-related macular degeneration (AMD) (Indicator E12a), glaucoma (Indicator E12b), diabetic eye disease (Indicator E12c) as well as the total numbers of certifications (Indicator E12d).

RESULTS

In 2017/18, the rate of new CVI certifications was 41 per 100,000 population which has reduced from 43/100,000 in 2010/11 in England. Certifications for AMD reduced from 132/100,000 in 2010/11 to 107/100,000 in 2017-18. Certifications for glaucoma have remained stable at 13/100,000 in 2017/8. Certifications for diabetic eye disease have declined from 4/100,000 in 2010/11 to 3/ 100,000 in 2017/18. The number of vision impaired individuals that each Clinical Commissioning Group (CCG) has to support varies from 8 to 82 per 100,000 population.

CONCLUSIONS

There has been a significant decrease in the rate of all CVI certifications particularly from AMD and diabetic retinopathy. However, maintaining this will require changes in the way care is delivered as the elderly population, which is at greatest risk of preventable sight loss, is projected to increase by 50% over the next 20 years. Inherited retinal diseases are now the leading cause of sight loss in the working age population. CVI data demonstrate the need for CCGs to tailor their investment in ophthalmic services to the needs of their specific patient populations. It is important that all ophthalmologists continue to provide accurate CVI data in order to help support the future equitable allocation of adequate resources to reduce avoidable vision loss.

Efficacy of Repeat Selective Laser Trabeculoplasty in Medication-Naive Open-Angle Glaucoma and Ocular Hypertension during the LiGHT Trial

PURPOSE

To determine the efficacy of repeat selective laser trabeculoplasty (SLT) in medication-naive open-angle glaucoma (OAG) and ocular hypertensive (OHT) patients requiring repeat treatment for early to medium-term failure during the Laser in Glaucoma and Ocular Hypertension (LiGHT) trial.

DESIGN

Post hoc analysis of SLT treatment arm of a multicenter prospective randomized controlled trial.

PARTICIPANTS

Treatment-naive OAG or OHT requiring repeat 360-degree SLT within 18 months. Retreatment was triggered by predefined IOP and disease-progression criteria (using objective individualized target IOPs).

METHODS

After SLT at baseline, patients were followed for a minimum of 18 months after second (repeat) SLT. A mixed-model analysis was performed with the eye as the unit of analysis, with crossed random effects to adjust for correlation between fellow eyes and repeated measures within eyes. Kaplan-Meier curves plot the duration of effect.

MAIN OUTCOME MEASURES

Initial (early) IOP lowering at 2 months and duration of effect after initial and repeat SLT.

RESULTS

A total of 115 eyes of 90 patients received repeat SLT during the first 18 months of the trial. Pretreatment IOP before initial SLT was significantly higher than before retreatment IOP of repeat SLT (mean difference, 3.4 mmHg; 95% confidence interval [CI], 2.6-4.3 mmHg; P < 0.001). Absolute IOP reduction at 2 months was greater after initial SLT compared with repeat SLT (mean difference, 1.0 mmHg; 95% CI, 0.2-1.8 mmHg; P = 0.02). Adjusted absolute IOP reduction at 2 months (adjusting for IOP before initial or repeat laser) was greater after repeat SLT (adjusted mean difference, -1.1 mmHg, 95% CI, -1.7 to -0.5 mmHg; P = 0.001). A total of 34 eyes were early failures (retreatment 2 months after initial SLT) versus 81 later failures (retreatment >2 months after initial SLT). No significant difference in early absolute IOP reduction at 2 months after repeat SLT was noted between early and later failures (mean difference, 0.3 mmHg; 95% CI, -1.1 to 1.8 mmHg; P = 0.655). Repeat SLT maintained drop-free IOP control in 67% of 115 eyes at 18 months, with no clinically relevant adverse events.

CONCLUSIONS

These exploratory analyses demonstrate that repeat SLT can maintain IOP at or below target IOP in medication-naive OAG and OHT eyes requiring retreatment with at least an equivalent duration of effect to initial laser.

Phenotypic and Functional Characterization of Müller Glia Isolated from Induced Pluripotent Stem Cell-Derived Retinal Organoids: Improvement of Retinal Ganglion Cell Function upon Transplantation

Glaucoma is one of the leading causes of blindness, and there is an ongoing need for new therapies. Recent studies indicate that cell transplantation using Müller glia may be beneficial, but there is a need for novel sources of cells to provide therapeutic benefit. In this study, we have isolated Müller glia from retinal organoids formed by human induced pluripotent stem cells (hiPSCs) in vitro and have shown their ability to partially restore visual function in rats depleted of retinal ganglion cells by NMDA. Based on the present results, we suggest that Müller glia derived from retinal organoids formed by hiPSC may provide an attractive source of cells for human retinal therapies, to prevent and treat vision loss caused by retinal degenerative conditions. Stem Cells Translational Medicine 2019;8:775&784.

Investigation of MicroRNA Expression in Experimental Glaucoma

MicroRNAs are small, endogenous noncoding RNAs that modulate post-transcriptional gene expression. Recent evidence suggests that they may have a potential role in the regulation of the complex biological responses that develop in response to elevated intraocular pressure. However, contemporary microRNA assay techniques (e.g., microarrays and next-generation sequencing) typically require large amounts of RNA template that are often times difficult to obtain from glaucomatous tissue. We describe in detail an experimental protocol utilizing targeted pre-amplification and low-density polymerase chain reaction arrays to circumvent this hurdle. This approach optimizes the simultaneous high-throughput screening of small tissue samples, such as the rodent optic nerve head, for up to 754 microRNA probes while also providing an opportunity for subsequent confirmatory reactions of technical or biological replicates.

Comparison of MicroRNA Expression in Aqueous Humor of Normal and Primary Open-Angle Glaucoma Patients Using PCR Arrays: A Pilot Study

Purpose

MicroRNAs (miRNAs) are small, endogenous noncoding RNAs that have been detected in human aqueous humor (AH). Prior studies have pooled samples to obtain sufficient quantities for analysis or used next-generation sequencing. Here, we used PCR arrays with preamplification to identify and compare miRNAs from individual AH samples between patients with primary open-angle glaucoma (POAG) and normal controls.

Methods

AH was collected before cataract surgery from six stable, medically treated POAG patients and eight age-matched controls. Following reverse transcription and preamplification, individual patient samples were profiled on Taqman Low Density MicroRNA Array Cards. Differentially expressed miRNAs were stratified for fold changes larger than ±2 and for significance of P < 0.05. Significant Kyoto Encyclopedia of Genes and Genomes pathways influenced by the differentially expressed miRNAs were identified using the predicted target module of the miRWalk 2.0 database.

Results

This approach detected 181 discrete miRNAs, which were consistently expressed across all samples of both experimental groups. Significant up-regulation of miR-518d and miR-143, and significant down-regulation of miR-660, was observed in the AH of POAG patients compared with controls. These miRNAs were predicted to reduce cell proliferation and extracellular matrix remodeling, endocytosis, Wnt signaling, ubiquitin-mediated proteolysis, and adherens junction function.

Conclusions

This pilot study demonstrates that miRNA expression within the AH of POAG patients differs from age-matched controls. AH miRNAs exhibit potential as biomarkers of POAG, which merits further investigation in a larger case-controlled study. This technique provides a cost-effective and sensitive approach to assay miRNAs in individual patient samples without the need for pooling.

A Period of Controlled Elevation of IOP (CEI) Produces the Specific Gene Expression Responses and Focal Injury Pattern of Experimental Rat Glaucoma

Purpose

We determine if several hours of controlled elevation of IOP (CEI) will produce the optic nerve head (ONH) gene expression changes and optic nerve (ON) damage pattern associated with early experimental glaucoma in rats.

Methods

The anterior chambers of anesthetized rats were cannulated and connected to a reservoir to elevate IOP. Physiologic parameters were monitored. Following CEI at various recovery times, ON cross-sections were graded for axonal injury. Anterior ONHs were collected at 0 hours to 10 days following CEI and RNA extracted for quantitative PCR measurement of selected messages. The functional impact of CEI was assessed by electroretinography (ERG).

Results

During CEI, mean arterial pressure (99 ± 6 mm Hg) and other physiologic parameters remained stable. An 8-hour CEI at 60 mm Hg produced significant focal axonal degeneration 10 days after exposure, with superior lesions in 83% of ON. Message analysis in CEI ONH demonstrated expression responses previously identified in minimally injured ONH following chronic IOP elevation, as well as their sequential patterns. Anesthesia with cannulation at 20 mm Hg did not alter these message levels. Electroretinographic A- and B-waves, following a significant reduction at 2 days after CEI, were fully recovered at 2 weeks, while peak scotopic threshold response (pSTR) remained mildly but significantly depressed.

Conclusions

A single CEI reproduces ONH message changes and patterns of ON injury previously observed with chronic IOP elevation. Controlled elevation of IOP can allow detailed determination of ONH cellular and functional responses to an injurious IOP insult and provide a platform for developing future therapeutic interventions.

MicroRNA Expression in the Glaucomatous Retina

PURPOSE

MicroRNAs are small, endogenous noncoding RNAs that modulate posttranscriptional gene expression. Although the contribution of microRNAs to the pathogenesis of glaucomatous damage is unknown, supporting evidence from central nervous system (CNS) research suggests they may play a role. It was therefore hypothesized that microRNAs known to be altered in CNS injury are also altered in experimental glaucoma.

METHODS

Intraocular pressure (IOP) was elevated in rats by unilateral injection of hypertonic saline and IOP monitored for 5 weeks. After rats were killed, retrobulbar optic nerve sections were graded for damage. MicroRNA was extracted from whole retinae of eyes with advanced nerve damage (n = 8) and from normal, noninjected control eyes (n = 8). Quantitative PCRs were performed using a panel of 17 microRNAs, reported from CNS research to be implicated in mechanisms also linked to glaucomatous damage. Computationally and experimentally derived gene targets were identified for the differentially expressed microRNAs. These were then integrated with existing gene array data. Functional interpretation was performed using the Molecular Signatures Database and DAVID Functional Annotation Clustering.

RESULTS

Eight microRNAs were significantly downregulated in glaucomatous retinae compared with controls (miR-181c, miR-497, miR-204, let-7a, miR-29b, miR-16, miR106b, and miR-25); miR-27a was significantly upregulated. Enrichment of targets associated with extracellular matrix/cell proliferation, immune system, and regulation of apoptosis were observed. Cholesterol homeostasis and mTORC-1 pathways showed reduced expression.

CONCLUSIONS

MicroRNAs are differentially expressed in retinae of eyes with advanced glaucomatous damage compared with normal controls. Integrating microRNA with gene expression data may improve understanding of the complex biological responses produced by chronically elevated IOP.

Regulatory T Cell Modulation by CBP/EP300 Bromodomain Inhibition

Covalent modification of histones is a fundamental mechanism of regulated gene expression in eukaryotes, and interpretation of histone modifications is an essential feature of epigenetic control. Bromodomains are specialized binding modules that interact with acetylated histones, linking chromatin recognition to gene transcription. Because of their ability to function in a domain-specific fashion, selective disruption of bromodomain:acetylated histone interactions with chemical probes serves as a powerful means for understanding biological processes regulated by these chromatin adaptors. Here we describe the discovery and characterization of potent and selective small molecule inhibitors for the bromodomains of CREBBP/EP300 that engage their target in cellular assays. We use these tools to demonstrate a critical role for CREBBP/EP300 bromodomains in regulatory T cell biology. Because regulatory T cell recruitment to tumors is a major mechanism of immune evasion by cancer cells, our data highlight the importance of CREBBP/EP300 bromodomain inhibition as a novel, small molecule-based approach for cancer immunotherapy.

Short Communication: Contribution of Voltage-Gated Sodium Channels to the Rabbit Cone Electroretinograms

PURPOSE

Although the rabbit eye is of a similar size to the human eye, our limited understanding of the differences in retinal physiology to other species hinders its use in retinal research. The role of voltage-gated sodium channels (Nav) in the propagation of excitatory potentials along bipolar cells remains unclear, as conflicting data have been reported in the rabbit. The present study assesses the relative contributions of Nav to the scotopic and photopic flash ERGs as well as the wavelength-dependence of Nav blockade on the rabbit flicker ERG.

MATERIALS AND METHODS

Tetrodotoxin (TTX, 1 μM) was injected into the vitreous cavity of Chinchilla bastard rabbits. Scotopic ERGs were evoked by white flashes ranging from 10(-5) to 10 cds m(-2), photopic ERGs on a background of 25 cdm(-2) using flash intensities of 0.032-25 cds m(-2). Flicker ERGs (3-50 Hz) were elicited by blue, green and yellow stimuli at 2.34 cds m(-2) on a white background of 30 cdm(-2).

RESULTS

The a- and b-waves of the scotopic ERG were unaffected by intravitreal injection of the Nav blocker TTX. In contrast, the b-wave, but not the a-wave, of the photopic ERG was selectively blocked by TTX. The reduction by TTX of the flicker ERG was greater for blue than for green and yellow stimuli.

DISCUSSION

The data suggest that Nav selectively contribute to the generation of the photopic b-wave in the rabbit, indicating that they play an important role in the propagation of excitatory signals on bipolar cells in the cone, but not rod pathways. Importantly, the present study resolves conflicting previous reports into the role of Nav in the retinal function of the rabbit.

Discovery of Benzotriazolo[4,3-d][1,4]diazepines as Orally Active Inhibitors of BET Bromodomains

Inhibition of the bromodomains of the BET family, of which BRD4 is a member, has been shown to decrease myc and interleukin (IL) 6 in vivo, markers that are of therapeutic relevance to cancer and inflammatory disease, respectively. Herein we report substituted benzo[b]isoxazolo[4,5-d]azepines and benzotriazolo[4,3-d][1,4]diazepines as fragment-derived novel inhibitors of the bromodomain of BRD4. Compounds from these series were potent and selective in cells, and subsequent optimization of microsomal stability yielded representatives that demonstrated dose- and time-dependent reduction of plasma IL-6 in mice.

Allogeneic Transplantation of Müller-Derived Retinal Ganglion Cells Improves Retinal Function in a Feline Model of Ganglion Cell Depletion

Human Müller glia with stem cell characteristics (hMGSCs) have been shown to improve retinal function upon transplantation into rat models of retinal ganglion cell (RGC) depletion. However, their translational potential may depend upon successful engraftment and improvement of retinal function in experimental models with anatomical and functional features resembling those of the human eye. We investigated the effect of allogeneic transplantation of feline Müller glia with the ability to differentiate into cells expressing RGC markers, following ablation of RGCs by N-methyl-d-aspartate (NMDA). Unlike previous observations in the rat, transplantation of hMGSC-derived RGCs into the feline vitreous formed aggregates and elicited a severe inflammatory response without improving visual function. In contrast, allogeneic transplantation of feline MGSC (fMGSC)-derived RGCs into the vitrectomized eye improved the scotopic threshold response (STR) of the electroretinogram (ERG). Despite causing functional improvement, the cells did not attach onto the retina and formed aggregates on peripheral vitreous remnants, suggesting that vitreous may constitute a barrier for cell attachment onto the retina. This was confirmed by observations that cellular scaffolds of compressed collagen and enriched preparations of fMGSC-derived RGCs facilitated cell attachment. Although cells did not migrate into the RGC layer or the optic nerve, they significantly improved the STR and the photopic negative response of the ERG, indicative of increased RGC function. These results suggest that MGSCs have a neuroprotective ability that promotes partial recovery of impaired RGC function and indicate that cell attachment onto the retina may be necessary for transplanted cells to confer neuroprotection to the retina. Significance: Müller glia with stem cell characteristics are present in the adult human retina, but they do not have regenerative ability. These cells, however, have potential for development of cell therapies to treat retinal disease. Using a feline model of retinal ganglion cell (RGC) depletion, cell grafting methods to improve RGC function have been developed. Using cellular scaffolds, allogeneic transplantation of Müller glia-derived RGC promoted cell attachment onto the retina and enhanced retinal function, as judged by improvement of the photopic negative and scotopic threshold responses of the electroretinogram. The results suggest that the improvement of RGC function observed may be ascribed to the neuroprotective ability of these cells and indicate that attachment of the transplanted cells onto the retina is required to promote effective neuroprotection.

Characterization of Staphylococcus aureus Cas9: a smaller Cas9 for all-in-one adeno-associated virus delivery and paired nickase applications

Background

CRISPR-Cas systems have been broadly embraced as effective tools for genome engineering applications, with most studies to date utilizing the Streptococcus pyogenes Cas9. Here we characterize and manipulate the smaller, 1053 amino acid nuclease Staphylococcus aureus Cas9.

Results

We find that the S. aureus Cas9 recognizes an NNGRRT protospacer adjacent motif (PAM) and cleaves target DNA at high efficiency with a variety of guide RNA (gRNA) spacer lengths. When directed against genomic targets with mutually permissive NGGRRT PAMs, the S. pyogenes Cas9 and S. aureus Cas9 yield indels at comparable rates. We additionally show D10A and N580A paired nickase activity with S. aureus Cas9, and we further package it with two gRNAs in a single functional adeno-associated virus (AAV) vector. Finally, we assess comparative S. pyogenes and S. aureus Cas9 specificity using GUIDE-seq.

Conclusion

Our results reveal an S. aureus Cas9 that is effective for a variety of genome engineering purposes, including paired nickase approaches and all-in-one delivery of Cas9 and multiple gRNA expression cassettes with AAV vectors.

Electronic supplementary material

The online version of this article (doi:10.1186/s13059-015-0817-8) contains supplementary material, which is available to authorized users.

Abstract A20: A leukemic model of acquired resistance to BET inhibition reveals a role for CBP/EP300 bromodomains in the regulation of c-MYC expression

Pharmacological modulation of c-MYC expression has recently become possible through small molecule engagement of the BET bromodomain proteins. As multiple BET inhibitors (BETi) progress through clinical trials, understanding possible mechanisms of acquired resistance becomes imperative to maximize therapeutic efficacy, assess possible drug combination strategies, and identify characteristics of next generation BET inhibitors. In the present study, we describe a cellular model of BETi resistance, which demonstrates a significantly blunted phenotypic and molecular response to BETi. The expression of c-MYC mRNA, highly susceptible to BETi in the parental cells, is restored in resistant cells through transcriptional bypass of BET-mediated co-activation. Through the use of a novel CBP/EP300 bromodomain inhibitor (CBP/EP300i), we show that c-MYC expression in BETi-resistant cells is dependent on CBP/EP300 bromodomain function, and that co-treatment with CBP/EP300i restores phenotypic sensitivity. CBP/EP300i was additionally found to transcriptionally silence MYC expression in numerous myeloma and leukemia derived cell lines in a manner comparable to BETi, identifying a novel modality to pharmacologically target the MYC oncogenic axis. While both BET and CBP/EP300 bromodomains regulate the expression of MYC, their transcriptional and phenotypic effects are otherwise distinct, suggesting that CBP/EP300 bromodomain inhibition may represent an alternative or complementary therapeutic option to BET bromodomain inhibition.

Citation Format: Andrew R. Conery, Richard C. Centore, Charlie Hatton, Adrianne Neiss, Hon-Ren Huang, Patricia J. Keller, Alexander M. Taylor, Alexandre Cote, Michael C. Hewitt, Christopher G. Nasveschuk, Yves Leblanc, Shihua Yao, Eneida Pardo, Laura Zawadzke, Florence Poy, Hari Jayaram, Shivangi Joshi, Peter Sandy, Anthony Romero, Terry Crawford, Richard Pastor, Tommy Lai, Kevin Chen, Jian Wang, Steven Magnuson, Brian K. Albrecht, Steve Bellon, Barbara M. Bryant, Robert J. Sims, III. A leukemic model of acquired resistance to BET inhibition reveals a role for CBP/EP300 bromodomains in the regulation of c-MYC expression. [abstract]. In: Proceedings of the AACR Special Conference on Myc: From Biology to Therapy; Jan 7-10, 2015; La Jolla, CA. Philadelphia (PA): AACR; Mol Cancer Res 2015;13(10 Suppl):Abstract nr A20.