Andrew Tatham: Make sure glaucoma doesn’t steal your sight

Glaucoma is a condition thought to affect half a million people in the UK with more than 50 per cent of all cases undiagnosed. It’s often referred to as the ‘thief of sight’ as it causes a gradual loss of peripheral vision. Patients can lose more than half their vision and still not notice. Once this has occurred, it can’t be reversed. The earlier we can identify and treat this condition, the better chance of saving people’s sight. Glaucoma can lead to blindness – in Scotland, there are 35,000 registered blind or ­partially-sighted people. More than two per cent of adults over 40 are affected by glaucoma. This is just the tip of the iceberg as many people with visual impairment are not registered. Sight loss has serious consequences. Two-thirds of working-age people with ­partial sight are not employed and older people with sight loss are three times more at risk of depression. It can lead to loss of ability to drive, to read, loss of independence and an increased fear and risk of falls.

The condition is caused when the eye’s natural drainage channels become blocked; fluid is unable to drain causing pressure in the eye to rise. Think of the optic nerve as a cable on a suspension bridge – it is made of approximately one million nerve fibres. Raised pressure puts a strain on the nerve causing the fibres to gradually break. If the nerve loses a large number of fibres it becomes weaker. To treat glaucoma, we need to lower the pressure in the eye, take the strain off the optic nerve and help protect what remains. The more damage, the lower the pressure needs to be. Eye pressure can fluctuate through the day so a ­single reading can be misleading. There are new devices, such as the ­Triggerfish contact lens, which can give us a full picture of pressure changes over a 24 hour period. New ‘keyhole’ procedures have also been introduced. Collectively these are known as Minimally Invasive Glaucoma Surgery or MIGS. These include the iStent and Xen Gel Stent procedures. The iStent is a tiny (1mm long) titanium tube that is implanted into the eye to lower intraocular pressure and reduce the need for eye drops in patients with glaucoma. It is the smallest surgical device used anywhere in the human body and is inserted into the eye’s natural drainage channel. This involves a short procedure often combined with cataract surgery.

The Xen Gel Stent is a new minimally invasive surgery that aims to reduce intraocular pressure by inserting a small drainage tube into the eye. The stent allows fluid to drain from the anterior chamber into a ­reservoir under the conjunctiva. We need to raise awareness of glaucoma and I’d encourage readers to have regular eye checks, especially those over 40. There are new and ground-breaking procedures available to help abate the thief of sight. Dr Andrew Tatham is a leading ophthalmic surgeon and glaucoma specialist at The Edinburgh Clinic and NHS. World Glaucoma Week runs from 12 to 18 March.

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