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This is a plain English summary of an original research article. The views expressed are those of the author(s) and reviewer(s) at the time of publication.

For people with advanced glaucoma, a type of surgery called trabeculectomy reduces pressure in the eye more effectively than eye drops. New research into the first treatment offered also found that surgery was likely to be more cost-effective than eye drops over the person’s lifetime.

Glaucoma is caused by a build-up of fluid in the eye. The most common type, open angle glaucoma, develops when the drainage channels in the eye become gradually clogged up. Excess fluid increases pressure and can damage the nerve that connects to the eye to the brain (optic nerve).

UK guidance recommends trabeculectomy surgery as the first treatment for people with this type of advanced glaucoma. However, the recommendation is not based on good quality evidence. As a result, many doctors who treat disorders of the eye (ophthalmologists) are reluctant to go for surgery straight away and prefer to start treatment with eye drops.

A team of researchers explored which is the best first treatment for people with advanced open angle glaucoma. They compared surgery with eye drops.

Surgery reduced pressure in the eye more than eye drops. However, in the 2 years of the study, the change in people’s vision and their quality of life was similar, regardless of which treatment they had. The research team would like to follow up participants for longer.

Eye drops were cheaper in the short-term but surgery was likely to be more cost-effective over the person's lifetime, the researchers say.

Further information on glaucoma treatment is available on the NHS website.

What’s the issue?

Around 2% of UK adults over 40 have glaucoma; it becomes increasingly common with age. The condition is usually caused by a build-up of fluid in the front part of the eye, which increases pressure inside the eye. This can damage the optic nerve, which connects the eye to the brain.

Open angle glaucoma, the most common type, can develop when the draining channels in the eye become gradually clogged over time. In the early stages, people have few symptoms. This means they often do not get diagnosed until their disease is advanced and they become aware of reduced vision. If left untreated, glaucoma can cause blindness.

Treatment can be eye drops, laser (selective trabeculoplasty) or surgery (most commonly trabeculectomy). This surgery involves making a small hole in the eye to let fluid drain more easily. UK guidance recommends surgery as first-line treatment; however, for people with advanced glaucoma, the recommendation is not based on strong evidence.

In practice, the first treatment is usually eye drops, with people going on to have surgery if their glaucoma is not adequately controlled. Many ophthalmologists are reluctant to begin with surgery, even in advanced disease, because of the potential risks of surgery and a lack of evidence to justify it.

Researchers wanted to find out whether surgery or eye drops were best for people in terms of both preventing vision loss and reducing glaucoma symptoms. They also wanted to see which was the safest and most cost-effective.

What’s new?

The study included 453 adults with advanced open angle glaucoma in at least one eye. They were being treated at 27 secondary care glaucoma departments. Most (65%) were men, and the majority (80%) were White. People were randomly assigned to receive either eye drops or trabeculectomy surgery.

In the eye drops group, prescribing was according to NICE guidelines (a prostaglandin analogue was usually used first, and further drops added if pressure was not sufficiently controlled. Any licensed eye drop could be used). In the surgery group, eye drops were prescribed by the surgeon, as is standard practice.

Two years after randomisation, the researchers compared the group who had surgery with the group using eye drops. They found few differences in terms of quality of life or safety.

People in both groups:

  • had similar declines in vision (some reductions are expected as people get older)
  • had similar vision-related quality of life scores
  • were similarly likely to report an adverse event (39% people in the surgery group reported events such as discomfort and blurred vision; 44% people in the eye drops group reported events such as redness and stinging).

However, there were differences between the groups:

  • eye pressure was lower in people who received surgery than in those receiving medical management
  • fewer people in the surgery group used eye drops; those who did, used far fewer than people who had eye drops alone
  • 39 people (17%) in the eye drops group needed surgery before the end of the study because of uncontrolled pressure in the eye.

Treatment with eye drops was cheaper over the 2 years of the study than surgery. This is mostly because of the higher initial cost of the surgery, including surgical staff and equipment. But the researchers say that surgery is likely to be more cost-effective over a person’s lifetime. Over the longer term, the reduction in eye pressure with surgery is likely to reduce the need for further treatment.

Why is this important?

This study supports current guidance from the National Institute for Health and Care Excellence (NICE). The guidance recommends trabeculectomy as a first treatment for people with advanced glaucoma. However, before this study, good quality research supporting the recommendation was lacking. Many ophthalmologists have therefore been reluctant to proceed with surgery first.

Surgery reduced pressure in the eye more than medical management with eye drops in this study. It concluded that surgery is therefore a better first-line treatment for people with advanced glaucoma.

What’s next?

The researchers would like to look at how people are getting on 5 years after surgery for glaucoma.

They would like to explore more suitable measures of quality of life for people with this condition. More work is needed on better ways of measuring patients' views of the impact their treatment had (patient-reported outcome measure).

Both ophthalmologists and patients may be reluctant to go for surgery as a first option for advanced open angle glaucoma since starting with eye drops has been routine for so long. The researchers say it is important that they know surgery is safe and effective for people with this condition.

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This NIHR Alert is based on: King AJ, and others. Primary trabeculectomy versus primary glaucoma eye drops for newly diagnosed advanced glaucoma: TAGS RCT. Health Technology Assessment 2021;25:72

Glaucoma UK: a charity dedicated to providing support, information and services to professionals and the public. 

Funding: This study was funded by the NIHR Health Technology Assessment programme.

Conflicts of Interest: The authors reported multiple conflicts of interest.

Disclaimer: NIHR Alerts are not a substitute for professional medical advice. They provide information about research which is funded or supported by the NIHR. Please note that views expressed in NIHR Alerts are those of the author(s) and reviewer(s) and not necessarily those of the NHS, the NIHR or the Department of Health and Social Care.

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