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How to Detect Hypertensive Retinopathy

O.D.s play a vital role in identifying and monitoring hypertension

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

As primary eyecare providers, we see patients on a daily basis who have high blood pressure. As a matter of fact, hypertension is the most common primary diagnosis in the U.S., affecting one in three (78 million) Americans, according to the American Heart Association, and that number is projected to increase to 111 million by 2030. Furthermore, many of these patients are unaware they have high blood pressure, and of those who are aware, only about half have it under control, according to the CDC.

Hypertension is a major risk factor for a multitude of conditions, including strokes, myocardial infarctions, renal failure, cardiovascular disease and early death. Though everyone is at risk for this disease, not everyone will have symptoms, making it a “silent killer.”

An eye-opening fact is hypertensive retinopathy (HTR) is an important warning sign, not only of hypertension, but also as a risk indicator of the aforementioned systemic conditions. Identifying even the early clinical findings can prevent vision loss and, more importantly, disability and premature death from hypertension.

HTR is a common finding, occurring in 50% to 80% of hypertensive patients, according to Ophthalmology. Patients with hypertension are prone to a spectrum of ocular complications, including retinal vascular occlusions, cranial nerve palsies, retinal arterial macroaneurysms, diabetic retinopathy progression, ocular ischemic syndrome, subconjunctival hemorrhages, vitreous hemorrhages and non-arteritic anterior ischemic optic neuropathy.

Early HTR findings, like arteriolar/venule (AV) crossing changes, are the hallmark of chronic disease. However, they can also have significant prognostic importance. For example, patients with normal blood pressure and early clinical signs of arteriolar narrowing have been found 60% more likely to be diagnosed with hypertension within a subsequent three-year period, according the Atherosclerosis Risk in Communities (ARIC) study.

O.D.s may be the first medical professionals a patient with high blood pressure encounters. Therefore, it is imperative that practitioners check for and identify signs of HTR.

Here, I discuss the clinical signs (see sidebar), diagnostic considerations and management protocols for HTR.

Diagnostic considerations

The five methods of diagnosis:

► Routine blood pressure screening. With the staggering number of people affected, particularly the undiagnosed cases, consider routine blood pressure screening on all patients age 18 and older. New automated blood pressure devices that can become more integrated in your practice are available, and a trained staff member can perform this simple test. Though a diagnosis of hypertension is never based on a single reading, you need to be aware of the numbers: 120-130/80-89 is pre-hypertension, where intervention may be necessary; and anyone with a blood pressure of ≥ 140/90 will require referral for further evaluation and possible treatment.

► Condensing lenses. The aforementioned early signs of HTR are important to ascertain, so you must pay attention to the blood vessels during all retinal examinations and particularly those of hypertensive patients. New condensing lenses aid in better visualization.

► Fundus photography. A key message from studies like the ARIC is that evaluation of retinal microvasculature changes, via retinal photography, aids in the assessment of stroke and cardiovascular disease risk.

Although a computer-based method for measuring retinal vascular caliber is not yet widely available, retinal photography is an excellent means of helping you detect early HTR. It is extremely valuable in documenting and managing, but most importantly, in educating patients about their condition. Thus, it should be performed on all patients who have hypertension.

► Spectral-domain OCT. OCT is an excellent tool for assessing macular, optic neuropathy and choroidal changes from hypertension. Emerging Doppler OCT technology may provide more information on HTR, as it enables you to look at blood flow together with the vascular and structural anatomy.

► Keith-Wagener-Barker Classification. It is important to determine the stage of the disease for progression and severity. The Keith-Wagener-Barker Classification system, for example, is a method of classifying the degree of hypertension (from 1 to 4) in a patient based on retinal changes. ■

Management protocols

Management protocols of HTR will vary based on your findings.

► High blood pressure. Patients with a blood pressure of ≥ 140/90 will require referral for further evaluation and possible treatment for hypertension. Your finding not only alerts the primary care physician, but also begins a conversation with the patient about the disease. Patients with high blood pressure and vague complaints of headaches, lightheadedness or vertigo require visual field testing or neurological evaluation, including imaging studies. As O.D.s are a critical part of the healthcare team, it is important to remind patients who have high blood pressure, despite medical therapy, about the importance of daily compliance to medication(s).

► Possibility of stroke. Arteriolar narrowing, arteriovenous nicking and increased arteriolar light reflex, all early signs of HTR, have been found associated with stroke risk. In fact, according to the ARIC study, a nearly twofold increase in the incidence of stroke was seen in patients with mild HTR. A subsequent study in Hypertension revealed that early HTR was associated with increased long-term risk of stroke, independent of other vascular risk factors.

Hypertension is an important modifiable risk factor. Therefore, O.D.s should communicate these findings to the primary care physician and monitor with routine care.

Patients with moderate HTR, retinal or flame-shaped hemorrhages and cotton wool spots were two-three times more likely to develop a stroke, according to the ARIC study. Follow these clinical findings closely with a six- to 12-week follow-up to assess whether blood pressure is controlled.

EB, a 46-year-old female, presented for her routine annual exam. She had no history of hypertension; however, retinal examination revealed hypertensive retinopathy, and in-office blood pressure was 160/100. Her primary care physician was alerted, and she was treated accordingly.

► Medical urgency or emergency. Patients with blood pressure greater than 180/110, a hypertensive urgency, require immediate medical care. Whereas patients with optic nerve swelling, macular edema and exudates, the hallmarks of malignant hypertension, a medical or hypertensive emergency, require prompt controlled anti-hypertensive treatment.

It important to note that rapid reduction of blood pressure in these patients may pose a risk of worsening ischemic damage to the optic nerve. This stage is associated with poor prognosis for survival. According to Ophthalmology, the mortality rate is 50% at two months and 90% at one year if untreated. A clinical pearl is that blood pressure should always be checked in the presence of bilateral optic nerve edema.

Patients experiencing severe headache, an altered level of consciousness or mental status and/or focal neurologic signs, such as transient ischemic attack, visual field defects, shortness of breath and seizures, require prompt care as well to assess for organ damage, such as heart damage.

In addition to prompt medical care to lower blood pressure, retinal management of the macular edema and optic neuropathy is required. These patients must be monitored every three months with visual field testing and OCT retinal and nerve fiber layer monitoring. ■

Under pressure

By detecting the warning signs of HTR, O.D.s can significantly impact not only the patient’s visual and systemic health, but potentially save his or her life. OM

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