Of all the problems diabetes can cause, its impact on eyes is perhaps the most frightening. Diabetes can damage your retina and double your risk of developing a cataract or glaucoma. With regular eye checks, however, you can halt the damage.

No one should take their sight for granted, but for the 270,000 New Zealanders diagnosed with diabetes, eye care takes on special relevance.

Widely accepted as the leading cause of avoidable blindness, diabetes can put extra pressure on the retina (at the back of the eye) as well as the lens (front of the eye), all of which can cause damage before symptoms even come to light.
The good news is, with close monitoring and regular eye checks, any serious problems can be detected and halted before your vision is at risk.


DIABETIC RETINOPATHY
Damage to your retina through diabetes is called ‘diabetic retinopathy’. This is a degenerative condition where high blood sugar causes damage to the small blood vessels in the eye, which can bleed, leek fluid and cause deposits in the retina.
At worst, diabetic retinopathy results in total loss of vision (or blindness), but fortunately the development of this condition is a process where the beginning part (and, to some extent, the middle part) can often be successfully treated or at least stopped from getting worse.

Almost everyone with diabetes will develop a mild form of retinopathy involving damage to existing blood vessels within the eye. But vision loss only tends to occur with more advanced retinopathy. Reduced vision is caused by two mechanisms: the first by the growth of new, very delicate blood vessels, which tend to haemorrhage into the eye, blocking vision, and the second by leakage and bleeding into the retina.

The earlier you have your eyes checked, the more that can be done for you. If your retina has been damaged, laser treatment may be necessary. Laser treatment seals leaking or new blood vessels, to prevent further damage from occurring. Surgical treatment may be needed for persistent cloudy vision or if scarring or tearing has occurred.


CATARACTS
Though cataracts are common in ages 55+, people with diabetes are twice as likely to develop a cataract. This is a result of accelerated damage created in a high blood sugar environment – a process compounded by the normal stress of ageing if you are diabetic. Cataracts are also linked to leakage of calcium and sodium through damaged cell membranes and oxidative damage in the lens.
For those with type 1 diabetes, a diabetic-specific cataract can develop called the ‘sugar cataract’. This type occurs at any age, but most commonly in young adults in their 20s who are in very poor control of their condition. Blood sugar control can prevent this serious development so utmost care should be taken to follow all precautions if you have diabetes.

If you do develop a cataract, it can nearly always be treated. Surgical procedures can involve removing the lens of an eye and implanting a new one – a move that sounds scary but these days is commonplace and highly successful.


GLAUCOMA
Glaucoma causes damage to the optic nerve which carries signals from the eye to the brain. Damage to this nerve can eventuate into blindness.

Glaucoma affects 2% of the population over the age of 40, and 10% of New Zealanders over the age of 70. As with cataracts, people with diabetes are almost twice as likely to develop glaucoma than people without diabetes.

Glaucoma occurs when pressure builds up in the eye. If fluid around the eye circulates and drains readily, then eye pressure will be low, but if there is resistance to drainage, eye pressure rises. If eye pressure becomes too high, the delicate structures of the eye can be irreversibly damaged. The level of pressure that will cause damage to an individual’s eye varies; around 30% of glaucoma patients have an eye pressure that would be considered normal. This means measuring the pressure alone will not detect all glaucoma and diagnosis can be complicated.

Although nerve damage and visual loss from glaucoma can’t be reversed, glaucoma is a disease that can be controlled when detected early. Lowering the pressure in the eye is a good starting point. Treatment can make the intraocular pressure normal and, therefore, prevent further nerve damage. Treatment may involve the use of eye drops, medication, laser, or surgery.


GLAUCOMA MAY HAVE NO OBVIOUS SYMPTOMS
No symptoms? This doesn’t mean you are off the hook. Pressure in your eye can build up and destroy sight without causing any obvious side-effects for some time.
In a few patients, however, it is possible to develop acute glaucoma which causes severe symptoms, including:

• Severe eye pain
• Headache
• Inflamed eye(s)
• Nausea
• Blurry vision.

With all the new advances in treating and preventing diabetes eye damage, Diabetes New Zealand says the number of people developing changes to their sight through diabetes is actually decreasing. By monitoring your condition and regularly checking your eyes, you can help ensure your own future is a bright and crystal-clear one.

OPTIMISING YOUR EYES
There are a number of lifestyle choices you can make to prevent or delay damage to your eyes…

• Have regular full diabetes eye checks (different to the eye check your GP may give you)
• Maintain healthy blood glucose levels
• Maintain a healthy blood pressure (high blood pressure has been shown to make eye problems worse)
• Quit smoking
• Eat a well-balanced diet (especially fruit and vegetables)
• Report any changes in your sight to your doctor
• Have regular checkups with an optometrist or ophthalmologist.

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