MIGS stands for minimally invasive glaucoma surgery, and refers to a range of implants, devices and techniques which all aim to reduce the pressure in the eye (intraocular pressure, or IOP).
Glaucoma is caused by the build-up of a fluid in the eye called aqueous humour. This causes IOP to increase, which damages the optic nerve and leads to vision loss. MIGS improves the drainage of the fluid out of the eye.
“Minimally invasive” means that they use tiny incisions and/or microscopic equipment, which have been designed to reduce risk compared to procedures such as a trabeculectomy or aqueous shunt.
This is a bit of a mouthful! A canaloplasty is a type of glaucoma surgery which cleans out the main drainage channel in the eye. Ab-interno just describes the direction from which the main drainage channel is accessed during surgery (from the front of the eye, in front of the pupil, instead of from the side). The iTrack is a tiny catheter (tube) which is inserted into the drainage channel. A special gel is injected through the catheter, which opens up the drainage channel and breaks down any blockages in the drainage channel. This means the flow of fluid out of the eye is improved, reducing IOP.
ECP is a laser probe which targets the part of the eye which produces the fluid in the eye, called the ciliary body. The laser reduces the activity of the ciliary body, meaning less fluid is produced which reduces IOP. The effect is temporary as the ciliary body eventually recovers, but the treatment can be repeated.
The Hydrus is an eyelash-sized device which is put into the main drainage channel of the eye (called Schlemm’s Canal). It acts as a scaffold to hold the drainage channel open and allow the fluid in the eye to drain, reducing IOP. It is made of nickel and aluminium.
The iStent is a one millimetre tube that is inserted into the natural drainage channel of the eye. It is made of titanium. It aims to bypass blockages in the drainage channel and so improve the flow of the fluid out of the eye and reduce IOP. It is common to have two or maybe even three iStent devices implanted into the eye to improve the chances of a good reduction in IOP.
The Preserflo Microshunt is a small tube that is inserted into the eye to create a new drainage pathway for the fluid. It acts as a bypass, with the excess fluid draining to a small blister (called a bleb) under the conjunctiva (the surface of the eye), under the upper eyelid. This improves drainage of the fluid in the eye, reducing IOP. It is made of a type of plastic.
A trabectome uses an electrical pulse to remove part of the blocked drainage channel. This helps the eye’s natural drainage pathway to start working again, allowing the fluid in the eye to drain and reducing IOP.
The XEN gel implant (pronounced ‘zen’) is a thin tube that is inserted into the eye to create a new drainage path for the fluid. It acts as a bypass, with the excess fluid draining to a small blister (called a bleb) under the conjunctiva (the surface of the eye), under the upper eyelid. This improves drainage of the fluid in the eye, reducing IOP. It is made of porcine gelatin (derived from pigs).
The Cy-Pass Micro-Stent is a very small tube which is inserted to bypass the eye’s main drainage channel and to improve another natural drainage pathway. This improves the drainage of fluid out of the eye, reducing IOP. It is made of a special plastic.
The Cy-Pass was withdrawn in August 2018, as research indicated people with a Cy-Pass had an increased risk of losing cells from the cornea (the surface of the eye). The device is no longer being used but it’s unlikely that people with a Cy-Pass will have it removed, as this is likely to cause damage to the eye.
If you have any questions about MIGS, please contact our helpline. Call 01233 64 81 70 or email helpline@glaucoma.uk (Monday – Friday, 9:30am – 5:00pm)
We are currently writing a series of fact sheets about the different MIGS. Please check back for more information soon.
There’s also a useful website, maintained by Mr Keith Barton, Consultant Ophthalmologist at Moorfields Eye Hospital in London: www.migs.org
In most situations, MIGS is suitable for people with mild to moderate glaucoma. It is common to combine MIGS with cataract removal. This is because cataract removal can reduce IOP, so helps with glaucoma. For more information, see our pages on cataract and glaucoma.
There are other treatments available for glaucoma which may be recommended to you, for example eye drops, aqueous shunt or laser.
Most of the MIGS surgeries are done under local anaesthetic, which means you will be awake but the eye will be numbed. Almost all MIGS surgeries themselves are very short – they may last a little as five minutes.
It usually takes around one to two weeks to recover from the surgery. It is likely you will have to use antibiotic or steroid eye drops for several weeks or months after any surgery to help recovery. You must attend follow-up appointments, to see whether the treatment is still working effectively to reduce eye pressure and that your eye is healing well, but the number of follow-up visits needed are usually much fewer than for surgery like trabeculectomy.
Any vision lost to glaucoma can’t be recovered, and glaucoma can’t be cured. All glaucoma treatments aim to stop further damage to the optic nerve and loss of any more vision.
For some people, the MIGS lowers IOP enough that they can stop using glaucoma eye drops, but this effect may only last a few years. Always follow the advice of your ophthalmologist regarding eye drops.
MIGS is a rapidly developing area of glaucoma treatment. New devices are regularly coming onto the market, while others are being altered or even withdrawn. While there’s a lot of excitement about the potential of MIGS, research is still needed to work out whether MIGS are better than more established treatments such as trabeculectomies or eye drops.
