Doing The Exai

The Big Diabetes Lie

Alternative Ways to Treat Diabetes

Get Instant Access

This chapter discusses macular edema resulting from microvascular leakage around the posterior pole. Basically, diabetes turns the retinal capillaries into the vascular equivalent of leaky old garden hoses. The result is that patients develop microaneurysms, hard exudates, and hemorrhages in varying amounts. If there is a lot of leakage from the damaged vessels, then the retina will swell up like a sponge. If this swelling builds up in and around the center of vision, then permanent damage can occur, and the goal is to identify swelling and treat it well before this happens.

Besides causing leaky blood vessels, diabetes can also just kill off blood vessels. Most of the time, there is a combination of both problems—vascular leakage and capillary death. In some patients, the destruction of blood vessels is the predominant problem, and this is referred to as capillary dropout or macular ischemia. This is always bad and it can cause marked vision loss; so far there is no treatment other than prevention with good systemic control and by trying to address any treatable leakage. Although capillary dropout can cause retinal edema at first as a result of ischemia, the end result is a thinned-out retina. It usually requires a fluorescein angiogram to identify this problem, although it can be inferred if patients have marked vision loss and an atrophic-appearing fovea. (Figure 7 is an example of capillary dropout around the fovea.)

Unless the patient is truly unlucky, ischemia is usually not a predominant feature in the early stages of diabetic macular edema. Instead, vascular leakage tends to be the initial finding. Because this leakage is very treatable, it is crucial to be able to identify the clinical signs that indicate the beginnings of damage. At the very start of your career it is exciting to simply be able to see these findings— your first direct glimpse of a disease hard at work. However, once you master the mechanics of examining the fundus it is easy to become jaded about spotting the signs of retinopathy. Try not to let this happen. You can get a lot of clues about a patient's situation just by looking carefully at each of the various manifestations.

For instance, you are no doubt aware that most intraretinal hemorrhages in diabetic retinopathy are blot-shaped because they stem from broken capillaries in the outer retinal layers, where the neurons are all jumbled together. As a result, the hemorrhage seeps out radially like a drop of food coloring on a paper towel. Flame-shaped hemorrhages occur when capillaries break in the more superficial nerve fiber layer, where the linear arrangement of the axons spreads the blood lengthwise rather than in all directions.

You may think that you are too cool to care about this second-year medical student stuff. You aren't. If a patient has an excessive number of flame-shaped hemorrhages and/or dot-blot hemorrhages, you should worry about the presence of additional vascular risk factors that are not well controlled. The most likely culprit would be superimposed hypertension, but you might also see this with progressive renal failure or anemia. Many such patients also have poor compliance—usually due to a combination of lack of motivation, lack of insurance or lack of a motivated primary-care doctor. Based on a few red smears it is possible to make massive inferences about everything from a patient's creatinine to their socioeconomic status—and your deductions and consequent actions can have a dramatic impact on how the patient responds to your ministrations.

Figure 1. A patient with macular edema and multiple hemorrhages. This patient had severe hypertension, early renal failure with secondary anemia and had been uninsured and unable to afford an eye exam until he could no longer function. You can infer a lot from a retina.

Figure 1. A patient with macular edema and multiple hemorrhages. This patient had severe hypertension, early renal failure with secondary anemia and had been uninsured and unable to afford an eye exam until he could no longer function. You can infer a lot from a retina.

Was this article helpful?

0 0
Supplements For Diabetics

Supplements For Diabetics

All you need is a proper diet of fresh fruits and vegetables and get plenty of exercise and you'll be fine. Ever heard those words from your doctor? If that's all heshe recommends then you're missing out an important ingredient for health that he's not telling you. Fact is that you can adhere to the strictest diet, watch everything you eat and get the exercise of amarathon runner and still come down with diabetic complications. Diet, exercise and standard drug treatments simply aren't enough to help keep your diabetes under control.

Get My Free Ebook


Post a comment