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DIABETIC RETINOPATHY

Sight threatening eye disease is a serious complication of diabetes and can often be present without visual symptoms. Early detection and appropriate management can greatly reduce risk of visual loss.

Ophthalmologic examination schedule

All T2DM patients must have a baseline visual examination at the time of diagnosis and yearly thereafter. The presence of retinal changes would merit more frequent examination schedules.

Similarly, in women with known T2DM who are planning pregnancy should have a preconception check and then during the first trimester. Women found to have diabetes during pregnancy (GDM) should also have a visual examination as soon as the diagnosis is made. The schedule thereafter would depend on the physician discretion dependent on the findings at the baseline examination.

BASELINE VISUAL EXAMINATION MUST include :

  1. History of visual symptoms.
  2. Measurement of visual acuity and intraocular pressure : refractive errors should always
    be corrected after a period of stable control ; cataract and glaucoma (with special
    focus on open angle glaucoma) are more common in diabetics and should be actively
    looked for.
  3. Ophthalmoscopic examination through dilated pupils.

This examination should be carried out by a person skilled in diagnosing diabetic eye involvement.

Patients at special risk, and those who show the presence of abnormalities, may require more frequent checkups; these patients should be seen along with a specialist.


PATIENTS AT SPECIAL RISK include:

  • women who are planning a pregnancy, must have a detailed eye examination
  • all pregnant women must have a detailed eye examination for the presence of retinopathy at the time of diagnosis and then as frequently as warranted.
  • patients with unexplained visual symptoms deterioration in visual acuity increased intraocular pressure any retinal abnormalities any other ocular abnormality that threatens vision.
  • patients with preproliferative retinopathy (multiple cotton wool spots, multiple intraretinal hemorrhages, intraretinal microvascular abnormalities venous beading.)
  • patients with proliferative retinopathy (retinal neovascularisation, preretinal or vitreous hemorrhage, fibrosis, traction retinal detachment.)
  • macular oedema (hard lipid exudates and/or retinal thickening in side the temporal vascular arcades).
  • presence of microalbuminuria, hypertension and smoking.

Stages of Retinopathy
  • Mild, nonproliferative retinopathy characterized by increased vascular
    permeability;
  • Moderate and severe nonproliferative diabetic retinopathy (NPDR), characterized by vascular closure;
  • Proliferative diabetic retinopathy (PDR), characterized by the growth of new
    blood vessels on the retina and posterior surface of the vitreous.

Macular edema, characterized by retinal thickening from leaky blood vessels, can develop at all stages of retinopathy.

For a more detailed chart showing the morphological and functional changes at various stages of diabetic retinopathy, see Appendix 12 a


Factors affecting progression of retinopathy

a) Duration of diabetes;
b) Uncontrolled glycemia;
c) Proteinuria;
d) High blood pressure;
e) Dyslipidemia;
f) Pregnancy and puberty;

Clinical Approach

Signs and Symptoms

There are usually no symptoms in the early stages of diabetic retinopathy. Vision may not change until the disease becomes severe. This is why regular examinations for people with diabetes are so important. But it may not be feasible to carry out a retinal examination at every visit. Thus, one should tell the patient to look out for signs and symptoms which may herald a serious problem and they should be told that they should seek medical attention urgently.

  1. vision becomes blurry;
  2. trouble reading signs or books;
  3. see double;
  4. one or both of the eyes hurt;
  5. the eyes get red and stay that way;
  6. feel pressure in your eye;
  7. see spots or floaters;
  8. straight lines do not look straight;
  9. can't see things at the side as one used to;

MACULOPATHY

Macular involvement in diabetic retinopathy is an emergency, and unless diagnosed in the very early stages and managed adequately, it can lead to significant visual loss (central vision loss).

It is recommended that all patients use an Amslers Recording Chart which allows early detection of maculopathy.

For details on the Amsler Recording Chart and its utility see Appendix 12 b

The Amsler's chart is very useful for early detection of macular problems and thus is very important as this may be an early sign of macular problems and lead to a loss of central vision.

It will NOT detect proliferative diabetic retinopathy, most preproliferative changes and other types of damage that may threaten vision, nor is it useful for detecting any of the early changes.

A normal Amsler grid test does not rule out the presence of retinopathy that can threaten vision and thus, cannot replace regular fundus examinations


MANAGEMENT strategies for Diabetic Retinopathy

lifestyle 30-60 minutes exercise a day, moderate alcohol consumption only, avoid obesity if possible, balanced diet including 5 portions of vegetables or fruit a day, with the minimal of animal or 'hard' vegetable fats, and very low salt.
blood pressure 130/80 or less125/75 or less if protein in urine present
HbA1c 6.5% or less with very few or preferably no hypos.If hypos develop, see expert advice.ACE inhibitors or AT11 unless young/pregnant/very low blood pressure/poorly tolerated
cholesterol <4.66mmol/l, and statins recommended for most adult patients
Smoking smoking 20 a day triples retinopathy (passive smoking: room-mates inhale at least 25%)

There are no known specific drugs which have been proven to be of help in reducing the progression of retionopathy, although some recent studies have shown that RAAS blocade may help in retarding the progression of diabetic retinopathy.

Laser photocoagulation therapy is effective in reducing the risk of further visual loss and is generally useful in preventing blindness in diabetics with high risk proliferative retinopathy and macular oedema. There is some evidence that early treatment with laser photocoagulation, without waiting for the development of severe changes, may lead to a better prognosis in preventing vision loss.

Vitrectomy may is the mode of treatment in patients with traction retinal detachment or vitreous hemorrhage.



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