Apolipoprotein B: Know Your Number

Branch Retinal Artery Occlusion and Central Retinal Artery Occlusion are two causes of permanent visual loss. The degree of visual loss in these conditions can range from very mild to very severe. In both conditions, visual loss is caused by arterial blockage due to a cholesterol plaque. In these instances, the plaque blocks nutrient-rich blood flow to the retinal cells, leading to impaired retinal cell function and, ultimately, visual loss. This is the same process that causes strokes in the brain and myocardial infarctions (heart attacks) in the heart. Once this occurs, the damage is irreversible except in very rare instances. Therefore, the best treatment is prevention.

Plaque formation occurs as a result of atherosclerosis, a process that takes place over several decades. During this process, excess lipids (fat) in the blood are deposited in the artery wall. These lipids undergo chemical reactions and aggregation, causing inflammation and subsequent narrowing of the artery. Over time, this excess material can break away from the artery wall and travel through the bloodstream, blocking small arteries and causing visual loss, heart attack, or stroke.

To assess a patient’s relative risk for atherosclerosis, the patient’s primary care physician (PCP) or internist will order a lipid profile. This generally consists of total cholesterol, HDL (good cholesterol), triglycerides, and LDL (bad cholesterol). Based on these values, if the patient’s PCP or internist feels the patient is at risk for atherosclerosis, they may prescribe medication, generally a statin. It is important to understand that LDL (bad cholesterol) is a calculated value rather than an exact measurement. Because of this, there is a need for a more precise measurement of bad cholesterol and a more accurate assessment of one’s atherosclerotic risk. This is where the measurement of Apolipoprotein B comes into play.

Apolipoprotein B is a molecule that carries small cholesterol particles (LDL). It is measured through a simple blood test that is inexpensive and covered by most insurance plans. It represents an actual particle count, as each Apolipoprotein B molecule carries one LDL particle. This makes it a far better test for assessing atherosclerotic risk, as it measures an actual number rather than relying on a calculated LDL value. Despite this, it is rarely ordered by internists and family medicine physicians, for reasons that remain unclear.

I believe many physicians are accustomed to long-standing practices and operate out of habit. Some may be risk-averse to adopting new approaches. Additionally, there may be political pressures and influences from the pharmaceutical industry that discourage changes in measurement standards. Fortunately, this is beginning to change. Apolipoprotein B is becoming increasingly recognized by researchers and clinicians as a more accurate standard for assessing atherosclerotic risk. I strongly recommend that, in addition to a standard lipid panel, patients have their Apolipoprotein B measured in order to more accurately determine their risk for atherosclerosis.

Paul N. Guerriero, MD, FAAO, FASRS
Diseases of the Retina, Vitreous, and Macula
Atlantic Eye

If you are interested in scheduling an eye exam with one of our award-winning physicians, please call us at 732-222-7373 or use our convenient online appointment form.