Summary: Researchers have used a purpose-built robotic device to deliver a single, targeted dose of stereotactic radiotherapy to treat wet (neovascular) age-related macular degeneration (AMD). This minimally invasive approach reduces the frequency of intravitreal injections required to control the disease.
A major clinical trial demonstrates that robotically guided radiotherapy can significantly lower injection frequency while maintaining vision, with potential cost savings for health services. By precisely focusing multiple beams of radiation on tiny lesions in the macula, the treatment stabilises disease activity and reduces patients’ treatment burden.
Key Facts:
- Robot-assisted stereotactic radiotherapy reduces the need for frequent anti-VEGF eye injections in patients with wet AMD.
- The system delivers highly focused, overlapping radiation beams to the macula, lowering disease activity without compromising vision.
- Trial data suggest the approach could produce net savings to the NHS by reducing the number of injections and associated costs.
Source: King’s College London
Researchers at King’s College London, working with clinicians at King’s College Hospital NHS Foundation Trust, have successfully tested a new robotic system that improves treatment for a sight-threatening form of macular degeneration.
The bespoke robotic device was used to administer a single, minimally invasive 16 Gray stereotactic radiotherapy (SRT) dose to the diseased eye in patients with chronic active neovascular AMD, alongside their ongoing standard anti-VEGF injections. The trial showed that patients who received robot-controlled SRT needed fewer injections over two years than those who received sham treatment.
Published in The Lancet, the pivotal, randomised, double-masked, sham-controlled STAR trial found that stereotactic radiotherapy reduced the mean number of anti-VEGF injections by roughly three over two years, a meaningful reduction in treatment burden that could translate into millions fewer injections worldwide.
Wet AMD occurs when abnormal new blood vessels invade the macula, the light-sensing layer at the back of the eye. These vessels leak blood and fluid, causing rapid and often permanent central vision loss. Globally, about 196 million people have AMD; in the UK, the Royal College of Ophthalmologists estimates more than 700,000 people are affected, with prevalence expected to rise as the population ages.
Current standard care relies on repeated intravitreal injections of anti-vascular endothelial growth factor (anti-VEGF) drugs. Although these injections often improve vision initially, they do not cure AMD, and many patients require ongoing injections every one to three months. Each injection can cost the NHS an estimated £500–£800, making anti-VEGF therapy one of the most common and costly outpatient procedures.
The robotic SRT approach uses three converging beams of highly focused radiation to target the macular lesion with sub-millimetre precision. In the STAR trial, participants who received robotically delivered 16 Gy SRT plus standard injections averaged 10.7 injections over two years compared with 13.3 injections in the sham-treated group, a statistically significant reduction after adjusting for treatment centre.
Economic analysis in the study estimated that fewer injections offset the upfront cost of the robot-guided procedure, saving the NHS an average of £565 per patient over the first two years. Investigators emphasise that these savings arise because SRT reduced the number of costly injections while maintaining comparable visual outcomes.
Professor Timothy Jackson (King’s College London and Consultant Ophthalmic Surgeon, King’s College Hospital) explained that previous attempts to repurpose radiotherapy devices lacked the precision required to treat tiny macular lesions. The new purpose-built robotic system achieves the accuracy needed to treat lesions that may be less than 1 mm across, using overlapping beams to concentrate dose on the diseased tissue while sparing surrounding structures.
“Patients accept that injections help preserve vision, but repeated hospital visits and eye injections are burdensome,” Professor Jackson said. “By stabilising disease activity and reducing injection frequency by about a quarter, this approach could substantially ease the treatment burden for many people.”
Dr Helen Dakin (University of Oxford) commented that the cost savings from fewer injections exceed the cost of delivering robot-controlled SRT, meaning the treatment can both control AMD effectively and free NHS resources for other patients.
Funding: The trial was jointly funded by the National Institute for Health and Care Research (NIHR) and the Medical Research Council (MRC). The study recruited 411 participants across 30 NHS hospitals. A Lancet-commissioned commentary described the trial as a “landmark trial.”
This multi-centre study was led by investigators at King’s College London and King’s College Hospital NHS Foundation Trust, in collaboration with the University of Oxford, the University of Bristol, and Queen’s University Belfast.
About this robotics and visual neuroscience research news
Author: Rebecca Lewis
Source: King’s College London
Contact: Rebecca Lewis – King’s College London
Image: The image is credited to Neuroscience News
Original Research: Open access.
“Stereotactic radiotherapy for neovascular age-related macular degeneration (STAR): a pivotal, randomised, double-masked, sham-controlled device trial” by Timothy Jackson et al. The Lancet
Abstract
Stereotactic radiotherapy for neovascular age-related macular degeneration (STAR): a pivotal, randomised, double-masked, sham-controlled device trial
Background
Neovascular age-related macular degeneration (nAMD) is a leading cause of central vision loss. First-line therapy consists of intravitreal anti-VEGF injections. Ionising radiation can modify pathogenic processes involved in nAMD and therefore has therapeutic potential. The STAR trial set out to determine whether stereotactic radiotherapy (SRT) reduces the number of anti-VEGF injections required without compromising visual acuity.
Methods
STAR was a pivotal, randomised, double-masked, sham-controlled trial conducted at 30 UK hospitals. The trial enrolled participants aged 50 years and older with chronic active nAMD who had received at least three prior anti-VEGF injections, including at least one in the previous four months. Participants were randomised 2:1 to receive 16 Gy SRT delivered by a robotically controlled device or sham SRT, stratified by treatment centre. Trial participants and staff, including image graders, were masked to allocation, apart from one unmasked statistician.
The primary outcome was the number of intravitreal ranibizumab injections over two years, tested for superiority (fewer injections). The main secondary outcome was best-corrected visual acuity at two years, tested for non-inferiority within a five-letter margin. Primary analysis used intention-to-treat; safety analyses followed per-protocol principles. The trial is registered with ClinicalTrials.gov (NCT02243878) and recruitment is closed.
Findings
Between Jan 1, 2015, and Dec 27, 2019, 411 participants were enrolled: 274 were randomised to 16-Gy SRT and 137 to sham SRT. Of these, 241 SRT and 118 sham participants were included in the final efficacy analysis; 409 patients comprised the safety population. The SRT group received a mean of 10.7 injections (SD 6.3) over two years versus 13.3 injections (SD 5.8) in the sham group, an adjusted reduction of 2.9 injections (95% CI –4.2 to –1.6; p<0.0001).
Change in best-corrected visual acuity in the SRT group was non-inferior to sham (adjusted mean difference –1.7 letters; 95% CI –4.2 to 0.8). Adverse event rates were similar between groups; however, microvascular abnormalities detected by the reading centre occurred more often in SRT-treated eyes (77 eyes, 35%) than in sham-treated eyes (13 eyes, 12%). Overall, eyes with these microvascular changes tended to have better visual acuity than those without.
Fewer ranibizumab injections offset the cost of SRT, with a mean saving of £565 per participant (95% CI –332 to 1483) over two years.
Interpretation
Robotically delivered stereotactic radiotherapy can reduce the anti-VEGF injection burden for patients with chronic active nAMD without compromising visual outcomes, offering a promising adjunct to standard care that may reduce costs and improve patient experience.