How to Follow Diabetic Retinopathy

Question: What’s the protocol for following patients with nonproliferative diabetic retinopathy?

Answer: Larry Alexander, O.D., of Louisville, Ky., says that when seeing diabetics, he errs on the side of safety. “Every diabetic deserves an eye exam every year, at least,” he says. This is despite recommendations for less frequent individualized screenings put forth in a study published in the Journal of the American Medical Association in February.¹ (The AOA, American Diabetes Association and American Academy of Ophthalmology all maintain the need for annual dilated eye exams for diabetics.)

Steve Bloom, M.D., a retinal specialist who also practices in Louisville, provides these basic guidelines for comanaging these patients:
 

• See those with mild nonproliferative diabetic retinopathy (NPDR) once a year.

• Schedule patients with NDPR and macular edema every 4-6 months.

• Examine those with clinically significant macular edema (i.e. edema close enough to the center of the retina to pose a risk to vision) every 3-4 months. 

• Schedule those who may require laser surgery in the near future about every 3 months.

• Refer patients with proliferative disease who need laser photocoagulation directly to the retinal specialist.

An additional method of assessing risk, Dr. Bloom says, is the “4-2-1 rule.” Any patient who exhibits any one of the following factors is at high risk for severe NPDR:

• Severe retinal hemorrhages or microaneurysms in four quadrants.

• Venous bleeding in at least two quadrants.

• Intraretinal microvascular abnormalities (IRMA) in at least one quadrant.

Any patient who has at least two of these factors is at severe risk of NDPR.

Ultimately, it’s up to your comfort level with your own skills to decide when to refer, Dr. Bloom says. He believes doctors should evaluate the progression of the disease based on their own clinical judgement, not the patient’s vision. “A patient who sees 20/20 can still need laser,” he says.

Dr. Alexander doesn’t always strictly follow the guidelines but tailors his evaluation to every patient, and keeps in close contact with the patient’s general practitioner or internist. He also considers the patient’s glycohemoglobin (hemoglobin A1c) test and blood pressure. If either is elevated, he considers the patient at significantly greater risk of developing diabetic retinopathy.

When examining a diabetic patient, use a 60D or 78D lens at the slit lamp, Dr. Bloom advises; a 90D lens doesn’t work as well. Another tip: A red-free green filter on the slit lamp makes diabetic retinopathy stand out more, he says.
 

Question: Is there a role for comanaging patients with proliferative disease?

Answer: Comanaging diabetic retinopathy is different than comanaging cataracts or refractive surgery, Dr. Alexander says. But the basic premise is the same: To comanage any condition, you must have adequate knowledge and education. “When the patient comes back to you after laser photocoagulation of retinal vein occlusion, you have to know what to look for,” he says.

The treatment for macular edema is either focal or grid macular laser photocoagulation, Dr. Bloom says. Re-evaluate these patients 3 months after treatment. If they still meet the criteria for treatment, they need to be retreated.

The treatment for proliferative diabetic retinopathy is panretinal photocoagulation. Usually one treatment does the job, Dr. Bloom says. But if the neovascularization is failing to regress or getting worse, then retreatment is probably necessary. Some people lose vision despite the treatment.

One last tip: Don’t change the patient’s spectacle prescription until all laser treatment is completed. Dr. Bloom says that sometimes the treatment can blur or temporarily change the prescription.

1. Vijan S, Hofer TP, Hayward RA. Cost-utility analysis of screening intervals for diabetic retinopathy in patients with type 2 diabetes mellitus. JAMA 2000 Feb 16;283(7):889-96.

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