This is a plain English summary of an original research article
Lens extraction, a procedure usually used to remove cataracts, could be a better first choice for some people with one type of glaucoma than laser treatment.
Glaucoma is a group of eye conditions which damage the optic nerve and eventually lead to blindness. Commonly the pressure within the eye is raised and nerve damage can be controlled by lowering the pressure.
Researchers randomly allocated 419 people with newly diagnosed primary angle-closure glaucoma to receive laser treatment, which is the usual management, or to have the lens surgically removed. After 36 months, those who had lens extraction had slightly lower eye pressure and higher scores on a health questionnaire, though the difference was of doubtful clinical significance. However, they were less likely to need further treatment other than eye drops.
One trial is not enough to change practice, but the results could be the start of an evidence base for lens extraction as a cost effective first-line treatment for people with primary angle-closure glaucoma.
Why was this study needed?
Glaucoma affects 2% of people aged 40 or more in the UK. Management is life-long and this is costly to the NHS and the individual. Glaucoma accounts for 10% of UK blindness registrations. The commonest type is “open angle” glaucoma which usually causes slow loss of vision. Angle closure glaucoma is less common but may cause rapid loss of sight and is more likely to lead to blindness.
Primary angle-closure glaucoma happens when fluid can’t drain out of the eye. It is usually treated by laser peripheral iridotomy, which opens parts of the eye that help fluid drain.
Lens extraction is usually reserved for people who also have cataracts. But age-related growth of a normal lens can also contribute to the pressure build-up in primary angle-closure glaucoma.
Researchers found no trials assessing lens extraction as the first therapy for this type of glaucoma in people without cataracts. This study aimed to assess safety, cost and effectiveness, compared to standard treatment.
What did this study do?
This randomised controlled trial, EAGLE, recruited 419 people from 30 hospitals, 22 in the UK and the others in Australia, China and East Asia.
Researchers recruited adults over 50 who were newly diagnosed with primary angle-closure glaucoma or its precursor primary angle closure. None of them had cataracts or previous eye surgery.
Researchers randomly allocated 208 people to clear-lens extraction surgery and 211 to standard care of laser peripheral iridotomy, followed by eye drops. They measured the results after 36 months, comparing eye pressure, overall health status and cost effectiveness.
The results of this large multicentre trial are likely to be reliable, although the surgeons and patients knew which procedures were carried out, introducing some bias. However, assessment of outcomes was objective.
What did it find?
All measurements were taken 36 months after the procedures.
- Average eye pressure following lens extraction was 16.6mmHg, compared to 17.9mm Hg for laser therapy, 1.18 mm Hg lower (95% confidence interval [CI] ‑1.99 to ‑0.38). Target eye pressure was 15 to 20 mm Hg so this small difference is unlikely to be clinically relevant.
- According to the European Quality of Life-5 Dimensions questionnaire (range 0 to 1, with 1 being perfect health), those with lens extraction had a slightly higher average score of 0.870, compared to 0.838 for laser treatment, a difference of 0.054 (95% CI 0.015 to 0.088).
- People who had lens extraction were less likely to have follow-up treatment. One person in the intervention group and 24 people in the laser treatment group needed further surgery. Medication to control eye pressure was required in 21% of people who had lens extraction compared to 61% of those who had laser treatment, though most people in each group required eye drops.
- Cost analysis based on 179 participants in UK centres found an incremental cost effectiveness ratio of £14,284 per quality-adjusted life year for lens extraction. The probability of lens extraction being cost effective, at the usual £20,000 threshold marking value for money in the NHS, was 67%.
- Three patients who had lens extraction and one patient who had laser treatment needed further surgery to manage complications. The researchers say extraction surgery “might be associated with severe intraoperative and postoperative complications”.
What does current guidance say on this issue?
The Royal College of Ophthalmologists recommends laser peripheral iridotomy for primary angle-closure glaucoma. Lens extraction is an alternative if there is a coexistent cataract, but they report that iridotomy may be necessary first in order to prevent acute angle closure from occurring during surgery.
What are the implications?
This high quality study suggests lens extraction treatment may be a useful option for first-line treatment of primary angle-closure glaucoma. Much of the benefit comes from not needing subsequent treatment. This also makes the treatment cost-effective, although initial costs of lens extraction are higher.
This study alone is probably not enough to change current practice on its own. Specialist ophthalmologists might consider offering lens-extraction to suitable patients on an individual basis, but must ensure they are aware of potential risks. Clinicians could record data from further treatments with lens extraction, to build a stronger evidence base.
Citation and Funding
Azuara-Blanco A, Burr J, Ramsay C, et al; EAGLE study group. Effectiveness of early lens extraction for the treatment of primary angle-closure glaucoma (EAGLE): a randomised controlled trial. Lancet. 2016;388(10052):1389-97.
This study was funded by the Medical Research Council. One of the researchers is supported by salary funding from the National Institute for Health Research through a grant to the Biomedical Research Centre at Moorfields Eye Hospital and UCL Institute of Opthalmology.
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