Eye Examinations


This page addresses the experience of having eye examinations for the detection of eye problems associated with having diabetes. More detail on eye disease can be found in the section 'Long Term Complications'.


Loss of vision may well be one of the most feared complications of having diabetes. However, good blood glucose control and early detection of any changes in the back of the eye could save your sight. The most common cause of blindness in people with diabetes is probably not catching retinopathy in its early stages. Timely treatment can prevent vision loss.

The Diabetic Retinal Screening, Grading, Monitoring and Referral Guidance 2016 updates all previous MOH guidelines and recommended:

  • revising the screening interval to three-yearly for those without clinical modifiers and for those with no diabetic retinopathy detected

  • updating the retinal screening pathway

  • making pupil dilation a choice to be discussed with the person being screened

  • focusing more on self management with better control if retinopathy progresses and timely re-screening if retinopathy control deteriorates

  • screening for pregnant women with diabetes

  • monitoring by optometrists, with each region having a central coordinator for its DR screening

  • service based on national standards and an ophthalmologist overseeing the region’s programme

  • encouraging the general practice as the health care home for people with diabetes, which includes accessing electronic information and ensuring enrolment with the screening programme, especially when a person with diabetes shifts to a different district health board (DHB) area

  • providing screening and monitoring results within three weeks to the person with diabetes, their GP and their referring clinician.


Once every two years you should have a dilated eye examination.This is usually checked as part of the 'Annual Review'. In most countries, guidelines recommend that people with diabetes have their eyes checked every year, as a routine part of the Annual Review. In New Zealand, however, screening is only performed once every two years and this is not necessarily performed at the same time, or in the same place, as the rest of the Annual Review - this means that, if your diabetes care is not efficiently coordinated, you may lose out. Make sure that you know how the diabetes eye screening programmes operate in your area, and make sure that you get your eyes checked at least every two years, without fail - even if you are experienceing no problems with your eyesight and your diabetes is well controlled.

Early detection of diabetic retinopathy is important. Once significant damage to the eyes has occurred it is not usually possible to restore vision - however, timely treatment can minimise any further deterioration, and may actually save your sight.



What's covered on this page


New Ministry of Health Guidelines (2016)

Routine eye examinations - what's involved?

Diagnosing diabetic retinopathy

Other investigations




New Ministry of Health Guidelines (2016)

Screening programmes are a relatively new initiative, designed to increase the number of people with diabetes having regular eye examinations. How your eye care fits in with the rest of your diabetes care will depend on the particular screening programme in your area.

The Ministry Of Health (MOH) published new guidance in 2016, which

>> Regional diabetic eye screening programmes in New Zealand

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Eye examinations - what's involved?

Where you go for your diabetes eye check up will depend on how the screening programme in your area works, and whether you have had diabetic retinopathy diagnosed. Some high street opticians will perform dilated eye examinations and other tests of eye health - however your diabetes health care team may prefer you to visit a specially accredited ophthalmologist (eye doctor). Check with your diabetes team if you are unsure.

In today's burgeoning digital era it is possible to have photographs of your eyes taken and sent electronically to the person coordinating your diabetes care.

If you have been previously diagnosed with retinopathy, or if you are pregnant, or planning a pregnancy, then you may be referred to a hospital eye clinic for your check-up.

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Preparation

When you have a diabetes-related eye examination you will probably need to have your pupils dilated (see below) - this is so that the person examining your eyes can get a really good look at the back of your eyes. The effects of the drops may linger, so it is advisable not to drive, and to take a pair of sunglasses with you. If you normally wear contact lenses, you can usually wear these straight after the eye examination, however it is advisable to take prescription glasses with you as well.

You should also take a list of all the medications you are on - for diabetes and any other conditions that you have.

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Visual acuity

'Visual acuity' is the technical term used to describe you well your eyes can read a starndard letters chart (known as the Snellen chart) at a given distance. Most people refer to "20/20" as perfect vision, although some people can actually see 'better' than this. The upper number refers to the standard distance, and is usually 20 ft. If your vision is 20/40 then you can see at 20 ft what a 'normal' person can see at 40 ft. Your visual acuity may be tested both with and without correction - i.e. with prescription glasses on and off - and should be assessed separately for each eye.

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Dilating the pupils

Normal pupils are 3-4mm in diameter in an 'average' lighted room. Adding drops to the eye that causes the muscle to widen the pupil can significantly increase the diameter - upto 7 or 8mm. This enables the entire retina to be seen through the pupil with relative ease. In addition, the 3-D stereoscopic view of the retina and the optic nerve is particularly important for the detection and management of macular edema and glaucoma. Many people with long-standing diabetes have smaller than average pupils, which makes dilation a necessity.

Eyedrops that are most commonly used are: Tropicamide 0.5%, and 1.0%, and Phenylephrine 2.5%

The eyedrops usually sting. Your eyes will water too, and you may look (and feel!) as if you are really about to burst into tears. This 'crying' sensation generally lasts for less than a minute. Within about 10 minutes or so, you will probably find that your close-up vision is becoming blurred, and bright lights will be appearing uncomfortably bright. If you look in a mirror, you will see that the dark circles at the centre of the coloured part of your eyes are becoming larger. You may look a bit 'wild'!

Depending on the combination of eye drops used by your eye doctor, your eyes may take anything from a few hours up to 24 hours to recover. You will need dark glasses and a driver during this recovery time.

If you normally wear contact lenses, you will need to remove these before your eye examination. Check with your eye doctor, but it is usually okay to re-insert your lenses after the eye examination is complete, although your pupils may still be a bit dilated. Prescription sunglasses are useful!

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Ophthalmoscopy

The term 'ophthalmoscopy' simply describes the process of looking at the inside of the eye, usually with an ophthalmoscope. This instrument consists of:

  • a concave mirror with a hole in the center through which the observer looks into the eye,
  • a light that is reflected into the eye by the mirror,
  • and lenses in the mirror which can be rotated into the opening in the mirror to neutralize the refracting power of the eye being examined making the image of the retina clear.

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Slit lamp examination

A slit lamp examination is usually a routine part of the eye examination; a lighted microscope is used to magnify your eyes. You sit at the apparatus, leaning forward slightly, put your chin on the chinrest, and allow your forehead to lean against the forehead rest. Your chair and the apparatus can both be adjusted so that you are sitting in a comfortable position.

The eye doctor uses a slit-shaped beam of light to examine various parts of your eyes (including the eyelids, cornea, anterior chamber, iris, and lens) in magnified detail. Most importantly, the area at the back of the eye, called the retina, is examined carefully.

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Diagnosing diabetic retinopathy

The diagnosis of retinopathy comes as a shock to many people, particularly if they have not been aware of any changes in their sight. If you have been having regular eye examinations and your diabetes is well controlled, then - hopefully - changes in the back of the eye will be detected early, and if any protective treatment (such as lasering) is required, this can be given to prevent further damage and help to prevent loss of vision.

Early changes to the retina usually do not require immediate treatment. Small swellings in the tiny blood vessels in the back of the eye (called microaneurysms) are usually the first signs of 'background retinopathy'. These appear as small red dots to the person examining the eye, and are often found in clusters.

As retinopathy advances, leakage of fluid and fatty material becomes evident, and 'cotton wool spots' may be observed. These suggest areas of the retina with a poor blood supply (ischaemia). Multiple 'cotton wool spots' may signify that the retinopathy is reaching the 'pre-proliferative' stage.

Many abnormalities of the tiny retinal blood vessels can be seen during a dilated eye examination as reinopathy progresses to the 'proliferative' stage. New fragile vessels grow; these vessels break, and can easily bleed into the eye. As the condition worsens scar tissue may be visible across areas of the retina, and as this contracts the retina may peel away from the eye causing loss of vision.

More details on the various stages of retinopathy, and information about treatments for retinopathy, can be found in the section "Diabetes and Your Eyes: Part 2".

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Other Investigations

Pupil and motility assessment

The doctor will shine a bright light in each eye to check that the pupils respond appropriately. Pupils should allow just the right amount of light into the eye and should become smaller in bright light and larger in the dark.

Electrical impulses travel from the retina to the brain through nerves. If your pupils do not respond appropriately, or if your eyes are misaligned, then there may be some problem with the nervous system controlling your eyes; this may be a problem specifically related to having diabetes (i.e. a cranial diabetic neuropathy).

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Glaucoma test

Your eye pressure should be regularly checked to test for glaucoma. Anaesthetic drops may be instilled in each eye, then an instrument called a tonometer is usually attached to the slit-lamp appartatus (see above). This is moved up to the surface of the eye until it is gently touching it; the doctor then reads the pressure off the gauge. The test is painless and takes only a few seconds to perform.

See "Diabetes and your Eyes, Part 1" for more information on glaucoma.

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Fluorescein angiography

If leage of blood vessels in the eye is suspected then a special dye test may be performed to specifically identify leaky vessels or areas. Fluorescein dye is injected into a vein. The dye is bright yellow and when it gets into the bloodstream it can help doctors to identfy blood flow - and therefore leakage. The test also helps to show any areas of the eye that do not have an adequate blood supply ('ischaemia' - see the section on retinopathy). Your eyes will be photographed and the pictures studied carefully, in order to identify any areas that may require treatment.

Some people feel nauseus when they have this test, but the effect does wear off. You will probably notice that your urine turns a dark yellow colour for about 24 hours, as the dye is gradually filtered out of the body by the kidneys. Your skin may turn a funny yellow colour too!

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Ultrasound

If the view of the back of the eye is obscured - either by a cloudy lens ('cataract'), or as a result of bleeding in the eye ('vitreous haemorrhage') - then ultrasound may be used to check for retinal detachment or other serious problems.

High frequency sound waves from a special probe bounce sound off the eye and give various echoes, which are used to derive a visual black and white image of the inside of the eye.

Using ultrasound effectively enables the doctor too 'see through' either a cloudy lens, or an eyeful of blood.

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