CLINICAL

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The Diabetes Evaluation

What is the O.D.’s role in the interdisciplinary team that manages patients who have diabetes?

SHERROL A. REYNOLDS, O.D., F.A.A.O., FT. LAUDERDALE, FLA.

The incidence of Diabetes Mellitus (DM) in the U.S. is rising at an alarming rate. More than 29 million Americans have diabetes, according to recent CDC figures, and one in four individuals (25%) don’t even know they have it. What’s more, another 86 million with pre-diabetes are headed down the road to diabetes without intervention, and the NEI projects diabetic retinopathy (DR) to climb to 11 million by 2030. In fact, the CDC estimates that every 24 hours, 55 people with diabetes become blind.

You, as the O.D., tend to see these patients more often than their primary care doctors because many of them have pre-existing visual issues. As a result, you need to be prepared to provide timely detection, prompt management and, most importantly, patient education, in order to prevent the onset and progression of DM-related vision loss.

Here, I provide additional reasons you play a significant role in this disease and what, specifically, this role is.

Why the O.D.

DM requires interdisciplinary care, and optometry is a key member of the team. DM can cause a multitude of ocular complications, including fluctuating or blurred vision and fluctuating refractive errors. Patients with diabetes are 40% more likely to develop glaucoma and 60% more likely to develop cataracts than patients who don’t have the disease, according to the American Diabetic Association (ADA). Moreover, diabetics develop cataracts at a younger age and at a faster rate vs. those who don’t have it. Other problems include cranial nerve palsies causing diplopia, ocular surface dryness, corneal disease, iris neovascularization (neovascular glaucoma), vascular occlusions and optic neuropathies (non-arteritic anterior ischemic optic neuropathy and diabetic papillitis).

Above, a dilated exam of a 55-year-old female with Type II DM and hypertension revealed proliferative diabetic retinopathy (PDR) OD. Her last eye exam was five years ago. Had she undergone yearly diabetic eye exams, early treatment would have been initiated before the development PDR.

DR and its associated pathology, including diabetic macular edema (DME), remain the most important ocular complications of DM. In some cases, DR is the initial sign of underlying disease in more than 21% of type 2 DM patients, reports the ADA.

In addition to the ocular complications, DM can cause an array of other complexities, including end-stage renal disease and non-traumatic amputation. Two major risk factors — disease duration and poor glycemic control — contribute considerably to the onset, severity and progression of complications. Other modifiable risk factors, including hypertension, dyslipidemia and obesity (body mass index/BMI), should be assessed as well.

As an optometrist, you possess the required skills to aid in the diagnosis of DM and effectively manage the associated vision problems.

The O.D.’s role

The earliest stages of DR (microaneurysms, intraretinal hemorrhages, cotton-wool spots and exudates) should be assessed with frequent examination intervals — every three to six months, especially if the patient’s ABCs of diabetes (see below) are poorly controlled. Vision-threatening retinopathy (extensive intra-retinal hemorrhages, cotton-wool spots, vein beading, IRMA, vitreous or pre-retinal hemorrhages, and neovascularization of the disc, retina and iris) and clinically significant DME require prompt care.

It’s important to note that DME can occur at any stage of DR, and with vision of 20/20. Some medications, such as rosiglitazone (Avandia, GlaxoSmithKline) and pioglitazone (Actos, Takeda Pharmaceuticals) have been reported to increase the risk of DME. So, you may have to be more vigilant in evaluating for DME among those patients taking these medications.

In addition to keeping a judicious eye out for the ocular sequelae of DM and treating and managing these patients accordingly, you also play an important role in enabling DM patients to better control their condition, as you tend to see them more often than their primary care physician.

Thus, you should learn the ABCs of diabetes — (A) glycosylated hemoglobin (HbA1c), (B) blood pressure and (C) cholesterol — and refer patients for these tests.

• HbA1c (A). HbA1c is a three-month blood test of glycemic control, with normal being ≤7. It is well established by landmark studies, such as the Diabetes Control and Complications Trial and United Kingdom Prospective Diabetes Study (UKPDS), that good glycemic control delays the development and progression of DR. Despite that, a recent paper published in the August 2014 Scientific Research’s Health found that the average HbA1c value for DM patients in the U.S. is 9.5, with about 23% describing their disease control as “good” or “excellent.” This highlights the lack of awareness among patients with diabetes of the importance of glycemic control and the need to reinforce this message, especially during an eye exam, when they are more aware of the implications of vision loss.

• Blood pressure (B). Often, diabetes and hypertension go hand in hand. Multiple trials, including the UKPDS, found that intensive blood pressure control slowed DR progression, improving visual outcome. According to the Eighth Joint National Committee on Hypertension (JNC 8), target blood pressure in diabetics should be less than 140/90, not the previous target of less than 130/80. However, this goal may not apply to all diabetics, for example, those with co-existing diseases. The bottom line: Close monitoring by you, their eye doctor, is important.

• Cholesterol (C). Finally, elevated cholesterol levels, particularly the “bad” low-density lipoprotein (LDL) and triglycerides, have been linked to DM complications, such as DR. The benefit of cholesterol-lowering medications in slowing the progression of DR/DME has been established by studies, such as the Fenofibrate Intervention and Event Lowering in Diabetes (FIELD) study. Recent reports have linked statins with a rise of blood sugar levels (hyperglycemia). Therefore, patients taking these medications should have their blood sugar level monitored every three months.

Another aspect of atherosclerosis is asymmetric DR. This should raise suspicion of ipsilateral carotid artery stenosis, and such patients should be referred for carotid artery testing.

Reigning in the sugar high

DM is a growing epidemic, making early detection and timely treatment critical to preventing vision loss. Optometry not only plays a key role in the diagnosis and management, but an ever-important role in patient education and interdisciplinary management in improving the health and vision outcome of DM. OM

Dr. Reynolds is an associate professor at the Nova Southeastern University College of Optometry. She is the clinical preceptor/attending in the college’s diabetes and macular clinic and a fellow in the Optometric Retinal Society. She serves as the chairperson for the Florida Optometric Association Healthy Eyes Healthy People Committee. Comment online at tinyurl.com/OMcomment.