It is triggered by fluid building up in the eye, and can lead to blindness if left untreated.
This new implant – which is 6mm long and the width of a hair – helps drain away the excess liquid.
As the 15-minute procedure doesn’t involve any incisions or stitches, patients are said to recover faster, with less risk of infection than with standard surgery.
Furthermore, the gelatine tube may be more effective at draining away fluid than other minimally invasive procedures. The eye naturally produces a watery fluid that fills the space between the lens and the cornea (the clear dome at the front of the eye), giving the eye its shape and providing it with nutrients. The fluid should drain away through tiny channels.
However, these channels can stop functioning effectively, though it’s not exactly clear why. As a result, fluid can’t drain away and pressure builds up inside the eye.
Over time this pressure damages the optic nerve that transmits visual images to the brain.
Glaucoma develops slowly, so there may be no noticeable symptoms, but regular eye tests mean it can be detected and treated early to prevent lasting damage.
Once diagnosed, patients are prescribed eye drops to reduce the pressure, for example by slowing down the production of fluid.
But drops can stop working as the disease becomes resistant to their effect, meaning alternative treatment is necessary.
The ‘gold standard’ procedure is a trabeculectomy. With the patient under anaesthetic, the surgeon cuts into the eye wall to create a new opening – or channel – allowing fluid to drain out.
But this carries the risks associated with surgery, such as bleeding and infection, and recovery of up to three months.
There are also treatments where doctors insert a metal tube, or stent, into the eye’s existing drainage channel.
She had the implant fitted in her left eye in March at the same time as having cataract surgery
This form of minimally invasive glaucoma surgery is quicker to perform and non-invasive compared to a trabeculectomy, so has a quicker recovery time (four weeks) and less risk of infection.
The new Xen Gel stent combines the benefits of trabeculectomy with those of minimally invasive surgery.
The implant – a small tube – is injected via hypodermic needle to sit just under the skin at the base of the cornea. This gelatine tube is similar in size to the metal tubes already used (which range in size from around 6.35mm to 8mm).
But unlike a metal stent inserted into an existing drainage channel, this hollow tube forms a new channel for fluid to drain through.
And because it is made of gelatine, it is better tolerated by the body and less likely to irritate the eye than metal or synthetic materials.
Because the implant is soft it should cause minimal damage to the cornea – a research paper published in the Journal of Cataract and Refractive Surgery last year concluded that it caused little disruption to the conjunctiva, the tissue covering the front of the eye.
‘The new implant is the first time that we’re able to do something as good as the gold standard, but quicker and safer and more comfortable for patients,’ says Vik Sharma, a consultant ophthalmologist at the Royal Free Hospital, North-West London, and clinical director at the London Ophthalmology Centre.
Another advantage over metal stents, he says, is that the implant creates a new channel in the eye. ‘If you’re putting a pipe into a channel that’s already blocked then studies show this doesn’t work effectively,’ says Mr Sharma, who has treated more than 60 patients privately with the new implant.
‘With this new way you’re not relying on the natural drainage system – you’re making a new channel, but without invasive surgery.’
Around a third of patients who have the Xen Gel implant will not need eye drops afterwards, compared with half of those who undergo a trabeculectomy, say surgeons.
Cathy Gosling had the implant fitted in her left eye in March at the same time as having cataract surgery.
The 65-year-old, who works in publishing, was diagnosed with glaucoma in 2010 during a routine eye check.
Though she did not have any symptoms and her vision wasn’t affected, the check revealed her eye pressure was getting high. A reading of 12 to 22 is normal – Cathy’s was 24 to 25.
Her optician referred Cathy, from East Finchley, North London, to Mr Sharma and the condition was managed for four years with eye drops.
However, six-monthly check-ups found the pressure was not consistently low enough, which meant that her optic nerve was becoming damaged. A trabeculectomy was not possible because Cathy was on drug-thinning drugs for an unrelated health problem, so couldn’t undergo surgery because it raises the risk of bleeding. Mr Sharma suggested the Xen Gel stent.
After the procedure (which costs £6,000 per eye), Cathy was sent home with eye drops and an eye patch, which she wore for a day. She was back to work within three days.
‘I was very nervous as it was done under local anaesthetic, but it didn’t hurt and I was home within two hours of the operation,’ says Cathy.
Glaucoma s triggered by fluid building up in the eye, and can lead to blindness if left untreated (file photo)
‘I felt discomfort in my eye for the rest of that day, but took paracetamol and by the following day the pain had subsided.
‘I couldn’t see out of my left eye at first, but by the next day my vision was getting back to normal and within a couple of days I could read normally. I can’t feel the stent in my eye.’
Her eye pressure is now normal (15 to 16). Though she is still using eye drops to ensure the pressure doesn’t rise again, it is only once a day compared with twice a day before.
Keith Barton, a consultant ophthalmologist at Moorfields Eye Hospital in London says the new jab is quicker, more comfortable and less invasive than a trabeculectomy, but won’t be the best option for all patients.
‘It’s not suitable for patients with advanced glaucoma – implant-type procedures are not as effective as a trabeculectomy at lowering eye pressure,’ says Mr Barton, who performs the new implant procedure privately and on NHS patients.
‘They only lower it to around 15, and patients with advanced glaucoma need much lower eye pressures because of the damage already caused to the optic nerve.
‘But for others it is the first treatment that offers an alternative to the gold standard.’
Helen Doe, a nurse from the charity the International Glaucoma Association, welcomed the new procedure, but said it wasn’t a ‘cure’.
‘Stents are still relatively new, though they’re less invasive than a trabeculectomy, so mean a faster recovery time. The question is, what is their longevity?
‘If you’re diagnosed at 40, then you could live for another 40 years. Their effects may not last this long.
‘And not all glaucoma is triggered by increased pressure – there are patients who suffer damage to the optic nerve, but tests show their eye pressure is normal – so we need more research into what exactly are the causes behind it.
‘However, the fact it is made of gelatine rather than metal means it is more biocompatible and won’t harm living tissue.’
The International Glaucoma Association helpline is 01233 648170, glaucoma-association.com