Diabetes Mellitus

Diabetic mellitus is a chronic, systemic, life-threatening disease that can affect the eye and nervous system, as well as the heart, kidneys, and other organs. People with diabetes are 25 times more likely to develop blindness than are individuals without diabetes. They are at a higher risk for glaucoma, optic neuropathy, and cataracts and are more likely to suffer visual loss from the effects of diabetic retinopathy. Diabetic retinopathy is the leading cause of new-onset blindness among working-age people in the United States.

The onset and the progression of diabetic retinopathy and its complications can be greatly influenced by the intensity of blood sugar control and by systemic factors such as pregnancy, serum lipids, hypertension, and kidney failure. In general, the longer a person has diabetes, the greater the chance of developing diabetic retinopathy. This is particularly true for persons with insulin-dependent diabetes mellitus (type 1) and those who have developed diabetes before the age of 30. Recent studies, however, have established that intensive control of diabetes with self-monitoring of blood sugar levels and multiple daily insulin injections can greatly slow the development and progression of retinopathy and other complications from either type 1 or type 2 (non-insulin dependent) diabetes.

Diabetic retinopathy usually causes no symptoms at its most treatable stages. Proliferative retinopathy, which often leads to blindness if not treated in a timely manner, can cause extensive damage before warning signs such as decreased vision occur. Early detection, careful follow-up, maintenance of intensive glycemic control, and judicious selection of the optimal time for laser photocoagulation surgery are essential for successful treatment of diabetic retinopathy.

Because of their fundamental role in the medical management, education, and coordination of care for the person with diabetes, the primary care physician and other allied health care professionals must be aware of the sight-threatening complications of diabetic retinopathy and available treatment. In addition, an effective partnership between the person with diabetes, the primary care physician, and the Eye Care Professional is essential to assure appropriate eye care.

The following guidelines are proposed for all involved health care professionals. Eye Care Professionals recommend:

1. People with diabetes should be informed of the following:

a. Sight-threatening eye disease is a common complication of diabetes mellitus and is often present even in patients with no ocular symptoms and good vision.

b. Early detection and appropriate treatment of diabetic eye disease greatly reduce the risk of vision loss.

c. Intensive management of blood sugar levels significantly reduces the development and slows the progression of diabetic retinopathy and visual loss.

d. Controlling high blood pressure significantly reduces the progression of diabetic retinopathy and visual loss.

e. Controlling abnormal blood lipid levels and high blood pressure can reduce the development of macular edema.

2. People diagnosed with diabetes before the age 30 should have a comprehensive eye examination by an Eye Care Professional by the time the diabetes has been present for 5 years or when the patient is 10 years old, whichever occurs later. If the time of the onset of diabetes cannot be accurately determined, a baseline examination should be performed soon after the time of diagnosis. This comprehensive examination should include:

a. medical, social, and family history;
b. history of medical symptoms;
c. history of visual symptoms;
d. measurement of visual acuity and intraocular pressure;
e. confrontation visual field evaluation;
f. review of ocular alignment and motility and of pupil reactivity and function;
g. evaluation of corneal and anterior segment findings;
h. ophthalmoscopic examination through dilated pupils using both stereoscopic biomicroscopy and indirect ophthalmoscopy.

3. People diagnosed with diabetes after age 29 should have a comprehensive eye examination by an Eye Care Professional , as specified in recommendation number 2 above, at the time of diagnosis.

4. After the initial eye examination, people with diabetes should receive an ophthalmic examination every year unless more frequent examinations are indicated by the presence of abnormalities.

5. Women with diabetes should be examined for retinopathy by an ophthalmologist prior to conception when possible and early in the first trimester of pregnancy. Subsequent evaluations may be performed at the discretion of the Eye Care Professional.

6. People with diabetes should be referred to an Eye Care Professional promptly for unexplained visual symptoms, reduced best corrected visual acuity, increased intraocular pressure, any retinal abnormality, or any other ocular condition that appears to threaten vision.

7. People with diabetes should be referred to an Eye Care Professional promptly for unexplained visual acuity, increased intraocular pressure, any retinal abnormality, or any other ocular condition that appears to threaten vision.

a. Severe and Very severe Nonproliferative Diabetic Retinopathy (NPDR, preproliferative retinopathy): often characterized by intraretinal microvascular abnormalities, venous beading, or multiple intraretinal hemorrhages and microaneurysms in all quadrants

b. Proliferative Diabetic Retinopathy (PDR): often characterized by optic disc and/or preretinal neovascularization, preretinal or vitreous hemorrhage, preretinal fibrovascular proliferation, or traction retinal detachment

c. Diabetic Macular Edema: characterized by retinal thickening or hard exudates within two disc diameters of the center of the macula

8. Surgical treatment alternatives should be provided promptly when indicated:

a. Timely laser photocoagulation surgery reduces the risk of severe visual loss (visual acuity <5/200) by 90%.
b. Laser panretinal photocoagulation is usually effective in reducing the risk of severe visual loss in patients who approach or reach high-risk proliferative retinopathy.
c. Persons with type 2 diabetes may benefit from panretinal photocoagulation at earlier stages (severe NPDR, very severe NPDR, or non-high-risk PDR) than that recommended for patients with type 1 disease (high-risk PDR).
d. Laser photocoagulation is also effective in reducing the rate of vision loss or stabilizing the visual acuity for patients with clinically significant macular edema.
e. Vitrectomy surgery can stabilize or improve vision in certain patients with recent traction retinal detachment or vitreous hemorrhage.
f. Laser surgery and vitrectomy should be performed by an ophthalmologist experienced in these techniques.
Eye Care Professionals seek to protect the health of all people with diabetes mellitus by stressing the importance of broad medical training for health care workers involved in the diagnosis and management of diabetic retinopathy and other ocular complications of diabetes. For optimal management of diabetic retinopathy, the responsible eye care professional needs to have a broad understanding of diabetes and be familiar with its manifestations in the organ systems affected. By training and education, ophthalmologists are the physicians uniquely qualified to diagnose and manage the ocular disorders associated with diabetes mellitus.
Approved by:
Continuing Education Secretariat
August 1999
Table 1.
Suggested Timetable for Initial Detailed Ophthalmologic Examination of People With Diabetes*
DIABETIC TYPE TIMING OF INITIAL OPHTHALMOLOGIC EXAMINATION
Type 1 Within 5 years of diagnosis or age 10 years, whichever occurs later
Pregnant women with type 1 or type 2 diabetes Prior to conception if possible and first trimester
RETINAL ABNORMALITY MINIMAL FOLLOW-UP ACTION
None or Minimal Nonproliferative Diabetic Retinopathy (NPDR)none or rare microaneurysms annually optimize control of serum glucose, hypertension, serum lipids, renal disease

Mild NPDRfew scattered retinal hemorrhages and serum microaneurysms every 6 - 12 months optimize control of serum glucose, hypertension, serum lipids, renal disease
Moderate NPDRmoderate hemorrhages and microaneurysms; hard exudates or soft exudates may be present every 6 - 12 months optimize control of serum glucose, hypertension, serum lipids, renal disease
Severe or Very Severe NPDROne or more of the following: · severe retinal hemorrhages and/or microaneurysms in all quadrants; or · moderate venous beading in =2 quadrants; or · moderate intraretinal microvascular abnormalities (IRMA) in =1 quadrant surgery every 1 - 4 months consider early scatter laser surgery as retinopathy progresses, especially with patients with type 2 diabetes
Macular Edemaretinal thickening in the macula occurring at any level of diabetic retinopathy every 2 - 4 months consider focal laser surgery if clinically significant macular edema is present; otherwise careful observation
Proliferative Diabetic Retinopathy (less than high risk)retinal neovascularization present but not reaching high-risk characteristics every 2 - 4 months
Proliferative Diabetic Retinopathy (high risk) · NVD within 1500 µm and =1/4 - 1/3 disc area; or · Vitreous or preretinal hemorrhage accompanied by NVD <1/4 - 1/3 disc area or NVE =1/2 disc area every 1 - 4 months consider laser surgery
Vitreous Hemorrhagepreretinal or vitreous blood every 1 - 3 months careful observation with serial B-scan ultrasonography as needed; pars plana vitrectomy if nonclearing hemorrhage or active retinopathy requiring laser surgery (which is prohibited by hemorrhage) or if retinal detachment threatens the macula
Retinal Detachmentretinal traction with detachment every 1 - 3 months pars plana vitrectomy if threatening macula; otherwise careful observation
Retinal Detachmentretinal hole present with detachment every 1 - 3 months pars plana vitrectomy with or without additional reattachment techniques if detachment involves or threatens macula or if peripheral detachment appears likely to progress
* To include detailed ophthalmoscopy through a widely dilated pupil and a search for other ocular conditions for which persons with diabetes are at increased risk (especially cataract and glaucoma); stereo color photography and fluorescein angiography where warranted. Usual intervals shown. More frequent examinations may be preferred. A thorough eye examination should also be performed if symptoms such as eye pain, redness, reduced corrected vision, floaters, light flashes, or other unexplained visual symptoms occur. Details of time-table and management of diabetic retinopathy can be found in the American Academy of Ophthalmology's Preferred Practice Pattern Diabetic Retinopathy.