The Impact of Baseline Intraocular Pressure on Initial Treatment Response in the LiGHT Trial: Selective Laser Trabeculoplasty versus Medication.

PURPOSE: The Laser in Glaucoma and Ocular Hypertension (LiGHT) Trial demonstrated the efficacy and safety of selective laser trabeculoplasty (SLT) compared to topical hypotensive medication as 1st-line therapy for ocular hypertension and open angle glaucoma. This sub-study explores the impact of pre-treatment (baseline) intraocular pressure (IOP) on treatment response for SLT and medication. DESIGN: Post hoc analysis of randomised control trial data. PARTICIPANTS: 1146 eyes from 662 patients were included in this analysis: 559 eyes in the SLT group and 587 in the medication group. METHODS: IOP reduction at 8 weeks following treatment with either SLT or prostaglandin analogue (PGA) eye drop initiation was assessed at different levels of baseline IOP, and the groups were compared. Differences in absolute and percentage IOP lowering between SLT and PGA medication were tested with a linear mixed effects model. Differences in the probability of achieving ≥20% IOP lowering between SLT and PGA medication, at different levels of baseline IOP, was estimated using a logistic mixed effects model. MAIN OUTCOME MEASURE: IOP lowering response to SLT versus PGA eye drops. RESULTS: Mean IOP was not significantly different between the groups, at baseline or 8 weeks following treatment initiation. Both treatments showed greater IOP lowering at higher baseline IOP and less IOP lowering at lower baseline IOP. SLT tended to achieve more IOP lowering than PGA drops at higher baseline IOP. PGA drops performed better at lower baseline IOP, and the difference compared to SLT, in terms of percentage IOP reduction, was significant at baseline IOP ≤ 17 mmHg. There was a significant difference in the relationship between baseline IOP and probability of ≥20% IOP lowering between the two treatments (p = 0.01), with SLT being more successful than PGA at baseline IOP > 22.51 mmHg. CONCLUSIONS: These data confirm previous reports of greater IOP lowering with higher baseline IOP for both SLT and topical hypotensive medication. In treatment naïve eyes, at higher baseline IOP, SLT was more successful at achieving ≥20% IOP lowering than PGA drops. At lower baseline IOP, a statistically greater percentage, but not absolute, IOP lowering was seen with PGA drops compared to SLT, although the clinical significance of this is uncertain.

Comparative Cost-effectiveness of Trabeculectomy versus MicroShunt in the US Medicare System.

PURPOSE: To assess the societal cost-utility of the MicroShunt compared with trabeculectomy for the surgical management of glaucoma in the US Medicare system. DESIGN: Cost-utility analysis using efficacy and safety results of a randomized controlled trial and other pivotal clinical trials. PARTICIPANTS: Markov model cohort of patients with open-angle glaucoma. METHODS: Open-angle glaucoma treatment costs and effects were analyzed with a deterministic model over a 1-year horizon using TreeAge software. Health states included the Hodapp-Parrish-Anderson glaucoma stages (mild, moderate, advanced, blind) and death. Both treatment arms received additional ocular hypotensive agents to control intraocular pressure (IOP). Treatment effect was measured as mean number of ocular hypotensive medications and reduction in IOP, which had a direct impact on transition probabilities between health states. Analyses of scenarios were performed with longer time horizons. One-way sensitivity and probabilistic sensitivity analyses were conducted to assess the impact of alternative model inputs. Both treatment arms were subject to reported complication rates, which were factored in the model. MAIN OUTCOME MEASURES: Incremental cost per quality-adjusted life-year (QALY) gained. RESULTS: At 1 year, the MicroShunt had an expected cost of US dollars (USD) 6318 compared with USD 4260 for trabeculectomy. MicroShunt patients gained 0.85 QALYs compared with 0.86 QALYs for trabeculectomy, resulting in a dominated incremental cost-utility ratio of USD 187 680. Dominance is a health economic term used to describe a treatment option that is both more costly and less effective than the alternative. The MicroShunt remained dominant in 1-way sensitivity analyses using best-case input parameters (including a device fee of USD 0). At a willingness-to-pay threshold of USD 50 000, the likelihood of the MicroShunt being cost-effective was 6.4%. Dominance continued in longer time horizons, up to 20 years. CONCLUSIONS: Trabeculectomy appears to be a dominant treatment strategy over the MicroShunt in the surgical management of glaucoma. More independent, long-term studies are required for the MicroShunt and other subconjunctival microstent devices to evaluate their use in clinical practice.

An acute intraocular pressure challenge to assess retinal ganglion cell injury and recovery in the mouse.

We describe a model of acute intraocular pressure (IOP) elevation in the mouse eye that induces reversible loss of inner retinal function associated with oxidative stress, glial cell activation and minimal loss of retinal ganglion cell (RGC) number. Young healthy mouse eyes recover inner retinal function within 7-days but more persistent functional loss is seen in older mice. Manipulation of diet and exercise further modify RGC recovery demonstrating the utility of this injury model for investigating lifestyle and therapeutic interventions. We believe that systematic investigation into the characteristics and determinants of RGC recovery following an IOP challenge will shed light on processes that govern RGC vulnerability in the early stages of glaucoma.

Double scleral tunnel technique to prevent glaucoma drainage device exposure.

PURPOSE: To describe a new surgical technique designed to reduce the risk of tube exposure following glaucoma drainage device (GDD) surgery. METHODS: A retrospective, single-center study included all patients who underwent GDD surgery by a single surgeon between January 2018 and December 2019, using a double scleral tunnel technique to secure the tube to the sclera. A 23-gauge needle was used to create a 3 mm partial thickness scleral tunnel near to the GDD plate, with a second partial thickness scleral tunnel created 2.5 mm from the surgical limbus into the anterior chamber (AC). The silicone tube was passed through both scleral tunnels and into the AC. RESULTS: 46 GDD surgeries were performed during the time frame. The mean age of patients was 65 ± 13 years. Mean follow up duration was 27.7 ± 8.15 months (range 11 to 44). Significant reductions in intraocular pressure and number of glaucoma medications were achieved. Zero exposures were recorded occurring during follow-up. CONCLUSION: This double scleral tunnel technique to secure the GDD silicone tubing firmly to the sclera may reduce micro-movements which have been purported to be associated with tissue erosion post GDD surgery. The addition of this simple technique to existing GDD surgery may reduce the risk of post-operative tube exposure.

Conjunctival erosion following a PRESERFLO® MicroShunt procedure.

PURPOSE: We describe a case of conjunctival erosion following a PRESERFLO® MicroShunt procedure, and the subsequent revision surgery. OBSERVATIONS: Conjunctival erosion was noted overlying the MicroShunt implant at postoperative week 11, 8 weeks following a bleb needling procedure for bleb encapsulation. A brisk leak was observed at the site of erosion. The patient underwent a subsequent revision procedure with repositioning of the MicroShunt implant and mitomycin C (MMC) application. CONCLUSION AND IMPORTANCE: Conjunctival erosion may be a relatively rare but important complication following MicroShunt surgery and may arise from a variety of risk factors. Extra care should be taken during bleb needling in the context of MicroShunt, and needling should be directed posteriorly, beyond the distal tip of the MicroShunt.

Prevalence of glaucoma in the Australian National Eye Health Survey.

AIM: To estimate the prevalence of glaucoma in Australia. METHODS: This was a population-based study of 3098 non-Indigenous Australians (50-98 years) and 1738 Indigenous Australians (40-92 years) stratified by remoteness. Each participant underwent a standard examination that included visual field assessment, tonometry and non-mydriatic fundus photography. Two fellowship-trained glaucoma specialists independently assessed relevant case notes (past ocular history, best-corrected visual acuity, frequency doubling technology visual fields, Van Herick grade, intraocular pressure and optic disc-centred photographs) and assigned a diagnosis ranked on a scale of certainty: none, possible, probable or definite glaucoma. RESULTS: A total of 4792 (99.1%, 3062 non-Indigenous and 1730 Indigenous) participants had retinal photographs in at least one eye that were gradable for glaucoma. The weighted prevalence of glaucoma (definite) in non-Indigenous Australians and Indigenous Australians was 1.5% (95% CI 1.0 to 2.2) and 0.6% (95% CI 0.4 to 1.1), respectively. When definite and probable cases of glaucoma were combined, rates were 3.4% (95% CI 2.7 to 4.3) among non-Indigenous and 1.6% (95% CI 1.1 to 2.3) in Indigenous Australians. Only 52.4% of non-Indigenous Australians and 28.0% of Indigenous Australians with glaucoma self-reported a known history of glaucoma. CONCLUSION: We estimate that 198 923 non-Indigenous Australians aged 50 years and over and 2139 Indigenous Australians aged 40 years and over have glaucoma. Given the high rates of undiagnosed glaucoma coupled with a significant ageing of the Australian population, improvements in case detection and access to low vision rehabilitation services may be required to cope with the growing burden of glaucoma.

Mini-Review: Impaired Axonal Transport and Glaucoma.

Glaucoma is increasingly recognized as a neurodegenerative disorder, characterized by the accelerated loss of retinal ganglion cells (RGCs) and their axons. Impaired axonal transport has been implicated as a pathogenic mechanism in a number of neurodegenerative diseases, including glaucoma. The long RGC axon, with its high metabolic demand and crucial role in conveying neurotrophic signals, relies heavily on intact axonal transport. In this mini review, we consider the evidence for transport disruption along RGCs in association with glaucoma and other intraocular pressure models. We give a brief overview of the axonal transport process and the methods by which it is assessed. Spatial and temporal patterns of axonal transport disruption are considered as well as the reversibility of these changes. Biomechanical, metabolic and cytoskeletal insults may underlie the development of axonal transport deficits, and there are multiple perspectives on the impact that transport disruption has on the RGC. Eliciting the role of impaired axonal transport in glaucoma pathogenesis may uncover novel therapeutic targets for protecting the optic nerve and preventing vision loss in glaucoma.