What is glaucoma?
Glaucoma is the term given to a group of eye conditions characterised by damage to the optic nerve
(the nerve responsible for sending visual messages to the brain). Primary open-angle glaucoma is the
most common form of glaucoma. This occurs when fluid in the eye cannot drain away properly,
leading to an increase in pressure within the eye (intraocular pressure) that damages the optic
nerve. As damage to the optic nerve results in a gradual loss of visual field, the intraocular pressure
needs to be kept under control.
What is the treatment for glaucoma?
Treatment for glaucoma includes medication in the form of eye drops, as well as laser treatment and
What is a trabeculectomy?
A trabeculectomy is a surgical operation which lowers the intraocular pressure (IOP), the pressure inside the eye, in patients with glaucoma. This is achieved by making a small hole in the outer wall of the eyeball (the sclera), which covered by a thin trap-door in the sclera. The aqueous humour, the fluid in the front chamber of the eye, drains through the trap-door to a small reservoir or bleb just under the surface of the eye, hidden by the upper eyelid. The trap-door is sutured (stitched) in a way that prevents aqueous humour from draining too quickly. By draining aqueous humour, the trabeculectomy operation reduces the pressure on the optic nerve and prevents or slows further damage to the optic nerve and further loss of visual field or central vision in glaucoma. Click here for further information about this.
What is an aqueous shunt?
An aqueous shunt is a small, tube -like drainage device, used to control intraocular pressure. It
creates an escape tunnel for excess fluid to drain from inside the eye into a small blister, or filtering
bleb located behind the upper eyelid. From there, the fluid is slowly absorbed into the bloodstream.
An aqueous shunt is designed to stay in the eye permanently, to help to keep the intraocular
pressure well controlled.
Well and aqueous shunt implantation improve existing vision problems?
Unfortunately, any damage to the optic nerve caused by glaucoma is likely to be permanent and
therefore the aqueous shunt will not help with any existing visual problems. By decreasing
intraocular pressure however, a shunt can help to prevent further loss of vision.
What are the benefits of an aqueous shunt device?
By draining away excess fluid from inside the eye, and aqueous shunt will help to relieve pressure
and prevent any further damage to the optic nerve. When compared to more traditional glaucoma
filtering operations, implantation of an aqueous shunt may result in fewer post-operative
complications that require any extra surgical intervention.
How is an aqueous shunt implanted?
The tube is inserted into the anterior chamber (the eye space in front of the Iris). The rest of the
tube is tucked away under the protective membrane (the conjunctiva) that surrounds the eye. This
creates a small escape tunnel allowing the excess fluid to drain away into the space under the
conjunctiva to form a filtering bleb. The conjunctiva is then securely closed with small stitches. The
procedure can be performed under local anaesthesia or under general anaesthesia. It is less invasive
than traditional glaucoma operations and has a shorter operating time.
How long does it take to recover after having an aqueous shunt implanted?
The operation is usually performed on a day case basis. Although it can take approximately 2-3
months for the eye to feel completely normal again, it will usually take 2-3 weeks to return to a daily
routine. Eyedrops are prescribed post-operative lead to help the recovery process.
Our glaucoma medicines still required after surgery?
For many patients undergoing implantation surgery glaucoma medicines are no longer required but
this is not the case for everyone. It may be necessary to continue taking glaucoma drops but the
drop in the dosage may be different.
Is it possible for the aqueous shunt to be rejected cause an allergic/adverse reaction?
A temporary blurring of vision is expected in the first 2-3 weeks after surgery but this should
gradually resolve. Sometimes a change of spectacle lenses required. Redness and swelling of the eye
are to be expected in the first few days after the operation but if redness of the eye increases or pain
persists, this must be reported to the surgeon. While it is very unlikely that a patient will experience
a more serious side effect, such as an allergic reaction or rejection of the device, visual problems,
headaches or pain/discomfort must be reported to the surgeon without delay.
What is the PRESERFLO TM MicroShunt?
This aqueous shunt is made of a soft, flexible biomaterial that conforms to the curvature of the eye.
The biomaterial does not cause an adverse immune response within the eye. It is less than 1 mm
thick and with a winged design.
The surgeons specialising in the management of glaucoma at the Face & Eye Clinic are Mr Leon Au and Mr Chris Hemmerdinger.
Please note that although glaucoma surgery can be performed under local anaesthesia alone, local anaesthesia with safe, conscious intravenous sedation given by a very experienced and skilled consultant anaesthetist (commonly referred to as “twilight anaesthesia”) is also available where requested. This form of anaesthesia is extremely popular with our patients and the effects are reversed very quickly. It enables local anaesthetic injections to be given painlessly with little recollection of the surgery, and helps to keep patients calm, relaxed and comfortable.
Any patients requiring general anaesthesia or who are unsuitable for surgery at our day case facility, the Face & Eye Clinic, will be treated by our surgeons in a local private hospital e.g. the Private Wing of Manchester Royal Eye Hospital