Leading the Way in Microinvasive Glaucoma Surgery
Posted on 23 October 2017
Microinvasive Glaucoma Surgery has many benefits and few drawbacks for patients with Open-Angle Glaucoma.
Medication to control glaucoma may cause unpleasant side effects and be costly for medical aids and patients alike. Microinvasive Glaucoma Surgery (MIGS), a relatively new surgical procedure, gives hope to patients with Open-Angle Glaucoma, allowing the majority of patients to reduce their medication. Only three hospitals in South Africa are currently offering the minimally-invasive surgery including Mediclinic Panorama and Mediclinic Upington hospitals.
‘When we do glaucoma surgery or offer glaucoma management, we have to make a diagnosis of glaucoma first,’ says Dr Jaco van Niekerk, an ophthalmologist at Mediclinic Panorama. ‘The most prevalent type of the condition is Open Angle Glaucoma. The normal water production in a patient’s eye is disrupted owing to various genetic and environmental factors. When the drainage system in a patient’s eye is out of balance, the pressure in the eye can rise and damage the optic nerve.
‘It is only once damage to the nerve is identified, by either looking at the size of the nerves or the retina nerve layer thickness, that we diagnose a patient with glaucoma. Once a diagnosis is made, we often prescribe chronic medication to manage the condition,’ he says.
As an alternative, some ophthalmologists recommend employing valves to drain intraocular fluid to the outer side of the eye under the normal tissue.
‘This is still an excellent modality but it depends on the patient’s stage of glaucoma as well as the medication he/she is on,’ says Dr Van Niekerk.
‘Since then an additional way of managing patents with less invasive techniques have been developed,’ Dr Van Niekerk adds.
‘For example, an external valve measuring about 2.8mm (Ex-Press Mini Glaucoma Shunt) is implanted in the eye. It has a success rate of over 85% in enabling patients to stop their eye drops within five years. Alternatively, patients can often use only one eye drop per day because the shunt helps to control their eye pressure,’ he says.
Microinvasive Glaucoma Surgery
Still not happy with the size of the shunts, the international ophthalmology community has come up with another solution to improve the natural outflow of the eye called Microinvasive Glaucoma Surgery (MIGS).
‘A canal in front of the eye called the trabecular meshwork drains the normal water back into the body. In some patients, however, this network of tissue becomes blocked. This increases the pressure, damages the nerve and results in glaucoma,’ he explains. In patients with an early or mild form of this condition, the new procedure offers hope of greatly decreasing their reliance on medication.
The new procedure
Measuring only 0.25mm, the iStents, as they are branded, have small holes at their centre. They are loaded in pairs onto a needle developed to implant the stents in the eye’s meshwork.
‘The surgeon creates a 2mm incision on the temporal side of the canthus (the corner of the eye where the upper and lower eyelids meet), we fill the eye with a jelly fluid and identify the meshwork,’ Dr van Niekerk explains.
The specially-trained opthamalogist aims for a line and implants the small stents into the normal drainage canal. The incision is left to heal naturally and the surgeon carefully vacuums out the synthetic jelly fluid during a minor 20-minute procedure.
Dr van Niekerk, who has completed about 12 of these procedures, explains patients have a 65 -68% chance of no longer requiring medication or they can reduce the number of eye drops they use from three drops to one drop. Still in its early stages, doctors don’t yet advocate stopping eye drops entirely while they gather more data on how patient’s eye pressure drops after the procedure.
The procedure is often performed in conjunction with cataract surgery because the surgeon already has access to the eye. ‘Once we remove the cataract and create more space, we have already created a drop in pressure in the eye which we augment even further with the stents,’ explains Dr van Niekerk.
While it’s theoretically possible to perform the procedure under local anesthetic, doctors recommend a general anesthetic because surgeons need to angle the patient’s head and keep it very still.
Early studies show strong results from a surgery which is minimally invasive and relatively easy for a trained surgeon to perform.