Glaucoma ‘thief of sight’

Dr Andrew Tatham is a leading ophthalmic surgeon and glaucoma specialist at The Edinburgh Clinic and NHS.

Glaucoma is a condition feared to affect half a million people with over 50% of all cases undiagnosed. It’s often referred to as the ‘thief of sight’ as it causes a gradual loss of vision, which affects the peripheral vision. Patients can lose more than half their vision and still not notice that they’re affected. Unfortunately, once this loss of vision has occurred, it can’t be reversed but the earlier we can identify and treat this condition with the best tailored treatments, the better chance we have of halting the effects and saving people’s sight.

Glaucoma can lead to blindness, which is a major problem. In Scotland, there are 35,000 registered blind or partially sighted people. Over 2% of all adults over 40 are affected by Glaucoma. We know this is just the tip of the iceberg as many people with visual impairment are not registered.

Sight loss has serious consequences for individuals, their families and society as whole. Two thirds of working age people with partial sight isn’t in employment, 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 there’s an increased fear and risk of falling.

The condition is caused when the eye’s natural drainage channels become blocked; fluid inside the eye is unable to drain causing the pressure inside the eye to rise. Think of the optic nerve as a cable on a suspension bridge – it is made of approximately one million individual nerve fibres. Raised pressure within the eye puts a strain on the nerve causing the fibres to gradually break. If the nerve loses a large number of fibres it becomes weaker.

Therefore, to treat glaucoma, we need to lower the pressure in the eye, take the strain off of the optic nerve and help protect what remains. The more damage there is to the nerve, 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 on the market such as the Triggerfish contact lens, the first developed to give us a better, full picture of any changes in pressure over a 24 hour period.

New “keyhole” procedures have also been introduced with quicker recovery than traditional surgery. 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 glaucoma 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 (bleb) under the conjunctiva.

We need to raise awareness of Glaucoma and I’d encourage readers to have regular eye examinations, especially if you are aged over 40. It’s also important that people know that there are new and ground-breaking procedures available to help abate the thief of sight!

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