Diabetes is a chronic disease where the body cannot regulate its blood glucose levels. This can be due to the body not being able to produce enough insulin or the body becomes insulin resistant. As a consequence, this has significant impacts on health especially the heart, kidneys, nerves, blood vessels and the eyes.
How does diabetes affect the eyes?
Diabetes can affect different parts of the eye and its severity depends on many factors such as the blood glucose control, blood pressure, cholesterol level and the duration of your diabetic status. There is a higher risk of diabetic eye problems including:
- Early Cataracts. Hazing and cloudiness of the crystalline lens in our eyes leading to reduced quality of vision
- Glaucoma. This condition happens when the pressure builds up in the eye causing damage to the main nerve (optic nerve)
- Retinopathy. Damage of the sensory layer at the back of the eye (retina) can occur leading to bleeds, fatty deposits and abnormal blood vessels. Usually defined by proliferative (excessive bleeding) or non-proliferative (localised haemorrhages).
- Macula Oedema. The macula is the area at the back of the eye that is responsible for central vision. Swelling of this can occur alongside diabetic retinopathy
Diabetic retinopathy is a leading cause of vision impairment and blindness. About 1.7 million Australians were reported to have diabetes with approximately 30% having early diabetic retinopathy.
What are the symptoms of diabetic eye problems?
In early stages of diabetic eye problems, it is difficult to notice as you may not experience any symptoms. With high glucose levels, blurry or fluctuating vision may occur. Once your blood glucose levels stabilise, your vision is expected to return to normal.
In more advanced stages, you may experience :
- Difficulty reading or seeing at night
- Glare sensitivity
- Blotchy or distorted vision
- Vision loss
It is more difficult to treat diabetic eye problems in the later stages, so it is important to have regular eye checks in order to keep your eyesight healthy.
What does a diabetic eye check involve?
Making an appointment for a diabetic eye check is simple and does not require a referral. All you need is to book with your local optometrist. Remember to mention that you are diabetic and bring any documents from your GP along with you to the eye test. Your GP may recommend an eye exam when you are first diagnosed with diabetes.
Your optometrist will perform an examination of your eyes and have a look for any signs of changes or problems. You may have eye drops put in to dilate your pupils, so the optometrist can have a better look at the back of your eyes. These eye drops can cause light sensitivity and blurry vision for a few hours, so you will be advised to wear sunglasses and have someone drive you home afterwards.
At the end of the eye exam, your optometrist will tell you the results and recommend your next review. The usual review period is every 1-2 years, but this varies based on the individual. If there is damage detected, your optometrist will discuss this with you and may decide to monitor or refer for treatment with an ophthalmologist. Treatments can include laser, surgery or injections into the eye.
Why is it so important to have eye checks regularly?
It is important to stay vigilant with your eyesight and to have an eye exam regularly. If you experience any symptoms, contact your optometrist as soon as possible. Early detection of diabetic eye problems means early treatment and a better chance of restoring your vision.
Below is a case of a diabetic patient losing vision a Perth optometrist saw. With appropriate management through referral for treatment, the patient’s vision was restored.
Steve*, a 54 year old gentleman has been living with type 2 diabetes for approximately 15 years. He noticed he was experiencing gradual, painless, vision loss in both eyes for a few months and this was slowly impacting his work. He repairs and paints cars for a living and found it difficult to distinguish colours and shades. This consequently caused him to incorrectly paint a car green instead of black.
Steve never got his eye health checked regularly and only attended to see his optometrist when he felt like he needed new glasses. When he went to visit his optometrist, he could only see 6/60 in the right eye, which is the biggest letter E on the letter chart, and his left eye was seeing 6/36, 2 lines smaller than the large E. They found he had severe proliferative diabetic retinopathy with macular oedema and was urgently referred to the ophthalmologist.
The ophthalmologist found multiple bleeds and fat deposits in both eyes and extensive scarring in the left eye (Fig 1). Steve’s blood test HbA1c glucose levels was around 12% which meant he had very poor control of his diabetes (the normal HbA1c is approximately 5-6%). Apart from needing to treat his eyes, it was even more vital for us to explain to him the importance of maintaining good control of his blood sugar levels. In the following days, he was treated with a type of laser to the eyes which helps to prevent further abnormal blood vessels formation.
Fig 1. Initial presentation of his right eye (left picture) and left eye (right picture).
After a month of recovery, Steve received further surgery to remove the pre-existing scar tissue in the left eye. A vitrectomy was performed which involved removing the vitreous jelly inside the eye that housed the scar tissue. Steve also required more laser and ongoing injections in both eyes to stop further growth of abnormal blood vessels.
These injections continued every month and his vision slowly improved. 4 months on (Fig 2), you can see the laser scars in the outer areas of the retina and the scar tissue in the central area of the left eye is not present anymore. His vision was improving but he was still unable to drive as his vision was below driving standards.
Fig 2. 4 months after the first visit, there is laser scar marks in the peripheral areas of his retina.
After almost 1 year of monthly injections, Steve’s vision improved to 6/9 in the right eye and 6/6 in the left eye, 6/6 is the Australian equivalent of 20/20 vision which is the line we normally expect people to see. The amount of bleeds, abnormal blood vessels and lipid deposits have drastically reduced since his first presentation (Fig 3). He can safely drive a vehicle again and can also appreciate colours allowing him to go back to work and properly paint cars the correct colour.
Fig 3. 11 months later, there are less bleeds, less abnormal blood vessels and less fat deposits.
Steve still requires ongoing injections to his eyes but at less frequent intervals than before. His HbA1c blood glucose levels are also more stable at around 5-6. If Steve continues to attend his regular appointments and stay on top of his blood glucose levels, it is expected there will be further improvement to his eyes. Regular eye checks with an optometrist is thus beneficial, particularly for diabetic patients for early detection and prevention of severe damage to the eye.
*names have been changed for patient confidentiality
To contact your nearest optometrist, head to the Optometry Australia website.
This article was written by Optometry Western Australia (Early Career Optometrists committee); a branch of Optometry Australia.