DIABETES AND THE EYE

Introduction:

Diabetes is now recognised as a chronic condition affecting multiple organs including the Eye. The 2 common types are:

Type I:
  • – Early onset
  • – Requiring Insulin immediately
Type II:
  • – Adult onset
  • – Usually require medication initially but may require insulin
  • – More common variety
    The incidence of diabetes is expected to double in the near future.

Disease Process:

Diabetes affects small blood vessels throughout the body including the Eye in 2 ways:

  1. Vessel damage
    This causes small blood vessels to leak blood and fluid to its surrounding tissues (retina) in the eye. If this occurs at the macula, it can lead to reduced vision.
  2. Vessel Closure/Blockage
    Small blood vessels block off leading to reduced blood flow. The eye is affected in 2 ways:
    * If blood supply to the macula is blocked off then vision is reduced
    * General blockage of blood vessels leads to reduced oxygen supply to the retina. The eye responds by “growing” small blood vessels to try to overcome the oxygen shortage. These vessels are fragile and can break leading to bleeding into the eye. Left untreated, scarring follows these vessels which can pull the retina away leading to “Tractional Retinal Detachment”. In severe cases, blood vessels can grow into the part of the eye that drains fluid from the eye leading to a painful condition called “Neovascular Glaucoma”. This results from significant buildup of eye pressure.

Risk Factors:

  1. Duration of Diabetes
  2. Control of Diabetes
  3. Raised BP
  4. Cholesterol Levels
  5. Kidney Disease
  6. Pregnancy

Investigations:

GP:
  • – BSL
  • – BP
  • – Chol: TG
  • – HbA1C

Eye Specialist:

  • – Fluoroscein Angiogram
  • – OCT

The HbA1C
This blood test provides a measure of diabetic control for the 3 months.
A good level is 6.5-7.0
>9.0 is not good
Reducing from 9.0 to 7.0 reduces risk of progression of diabetic retinopathy by 50%.

Treatment:

  1. Medical Treatment
    Improve blood sugar control, reduce blood pressure and cholesterol.
  2. Laser Treatment
    There are 2 types of treatment:

    1. Macular Laser:
      Here laser is used to treat leaking blood vessels. As the leakage reduces, the fluid causing a swollen retina resolves.
      The treatment may need to be repeated.
    2. Scatter Laser:
      Here laser is used to treat areas of retina starved by oxygen.
      Studies have shown that it causes the fragile new blood vessels to shrink away reducing the risk of bleeding into the eye
      Treatment usually involves 3 to 4 sessions of laser treatment spaced 2 to 3 weeks apart.
      Occasionally patients can experience discomfort during this form of treatment. If it cannot be tolerated, the eye can be numbed by a local anaesthetic needle for the laser treatment.
    3. Intravitreal Injections:
      Here, medicines are injected into the eye cavity with a very fine needle under local anaesthetic.
      Studies have shown this treatment to be effective in diabetic vessel leakage and blockage.
      There are various agents available.
      These include Avastin, Triamcinolone.

Your doctor will discuss with you the pros and cons of each treatment drug.

In many cases, the injections will be combined with laser treatment. In severe cases of diabetic eye disease, multiple injections may be required.

Surgery:

In severe cases where bleeding has occurred into the eye or when there has been a retinal detachment, surgery will be required.

Surgery can remove blood from inside the eye to enable faster improved vision and permit other treatments like laser to proceed.

Outlook:

Studies have shown that with the appropriate screening, follow-up and timely treatment, the risk of blindness can be reduced by more than 90%.

Take home Points:

  1. Always attend the eye check-ups as arranged by your specialist. Good vision does not rule out sever potentially blinding diabetic eye disease.
  2. If you have symptoms of reduced vision or the sudden onset of floaters, see your eye specialist immediately.

Click here to download our Diabetes & the Eye Fact Sheet