Book Excerpts

Diabetic Eye Disease:
Lessons From A Diabetic Eye Doctor
(How To Avoid Blindness and Get Great Eye Care)

 from Chapter 1: Lessons From A Diabetic Eye Doctor
What is "Good" Diabetes Management?

Good diabetes management covers the span of an individual's diabetic life (from the time of diagnosis forward) but consists of a series of management decisions, treatments and goals that change as a person's body changes (both due to the normal aging process and the development of complications), as new treatments become available, and as new strategies for improved control are learned. This point cannot be stressed enough. Like most chronic health conditions, there is no 'magic bullet' for diabetes control. No "system" works perfectly forever, and strategies must often change to keep up with changes in one's health status. With advances in medical knowledge and biotechnology, the "gold standards" of today will undoubtedly become antiquated and sub-standard in the future. The history of medical science is filled with examples of this phenomenon.

What does "good diabetes management" mean? Foregoing medical jargon for now, a reasonable definition might be: "controlling diabetes in such a way that the person in question is able to experience life in the fullest way possible without insurmountable physical disability caused by diabetes and with a minimum of emotional stress." Put more simply, good diabetes management means a patient suffers the dreaded complications of diabetes to the smallest degree possible with the least hassle possible. It does not necessarily mean patients will have no complications (although that is certainly a worthy goal), only that those complications, if they occur, will not prevent patients from reaching their life goals or maximizing their unique human abilities.

Controlling diabetes effectively is an individualized effort, but it should not be an individual one. Controlling diabetes should be a team effort amongst the patient, her or his family and closest friends, and a team of health care professionals who are knowledgeable about and keenly interested in diabetes. I am intimately familiar with several different strategies for controlling diabetes, both as a Type 1 diabetic for 34 years, and as a doctor of optometry managing the eye complications of diabetes for the last 12 years.

I have managed my own condition differently at different points in my life, and I have seen several thousand of my own diabetic patients manage their conditions using a variety of different strategies. Some diabetics ignore their disease, living life exactly as they did prior to diagnosis. Others meticulously monitor their blood sugars, medications and diets, frequently consult with health care professionals to check for the earliest signs of diabetes complications, read many journal articles describing all the latest diabetes research, and attend lectures on every aspect of diabetes management. Most diabetics probably fall somewhere between these two extremes. Somewhere in between is where I started 34 years ago...

...The evolution of my strategies for managing my diabetes has not been easy, and there have been many setbacks along the way. I still have some high blood glucose readings due to over-indulgence, forgetfulness, illnesses like the occasional cold or flu, poor planning, stress and the vagaries of human existence. I very nearly lost my eyesight and was heading toward kidney failure, so my lifelong diabetes management strategy certainly has been no paragon of virtue. Of course, I will have to continue managing my diabetes for the rest of my life, or until a definitive cure is found...

from Introduction to Section II - Diabetic Eye Disease

In this section, we will consider in some detail the several different forms of "diabetic eye Disease," building upon the fundamentals discussed in previous chapters and stressing the steps every diabetic can and should take to reduce the risk of eye complications. Importantly, many of these risk reduction strategies will have the added benefit of reducing the risk of all diabetes complications, both microvascular (eyes, kidneys and nerves) and macrovascular (heart, brain and large blood vessels).

When thinking about the eye complications of diabetes, most people, including most health care professionals, think of diabetic retinopathy, the process through which the eye's light sensitive retina is damaged by chronic hyperglycemia. Indeed, diabetic retinopathy is arguably the most important example of diabetic eye disease, as it accounts for more than 22,000 cases of legal blindness each year in the United States, and more than 200,000 cases annually Worldwide. However, diabetic retinopathy, which has several different forms and stages, is itself only one of several completely distinct types of "diabetic eye disease." Recognition and understanding of each of these particular types will help health care providers and patients alike to recognize specific eye and/or vision symptoms related to previously diagnosed diabetes and, perhaps, to suspect undetected cases of diabetes when a clinical diagnosis has yet to be made.

There are seven different "diabetic eye diseases": diabetic cataract; glaucoma; diabetic keratopathy; diabetic optic neuropathy; diabetic cranial neuropathy; diabetic retinopathy; and retinal vascular occlusion. Each affects a different part of the eye, from the nerves that control eye movement to the nerve that connects the eye to the brain, from the front surface of the eye to its innermost internal layers. To better appreciate these various diseases, it will be helpful to conduct a "crash course" of sorts in ocular (eye) anatomy.

From there, we will explain the various kinds of diabetic eye disease, the treatments available for each and the things you can do to prevent or minimize vision loss from diabetes. Finally, we will consider the necessary elements of a thorough diabetic eye examination, including questions to ask your eye doctor and questions she should ask you, as well as some very important information about what to do if and when diabetic eye disease causes significant visual impairment.

It is extremely important that all diabetics understand a fundamental distinction between good eyesight and good eye health. The ability to see clearly (on an eye chart test or in the real world) is not equivalent to having healthy eyes. Many patients with serious eye disease have excellent eyesight, and the vast majority of patients who require eyeglasses or contact lenses to see clearly have healthy eyes. Just as for many patients with heart disease or cancer, patients with eye disease often have no symptoms until it is "too late." Regular, comprehensive eye examinations by an eye care professional (optometrist or ophthalmologist) are the best way to ensure both good eyesight and good eye health.

from Chapter 11 - Diabetic Retinopathy

Diabetic retinopathy is perhaps the single most important cause of adult blindness in the Western World, and almost 15% of all blindness in the United States is caused by diabetic retinopathy. This statistic takes on added economic significance when we consider the fact that many of these cases occur in younger adults who are often in the prime of their income earning years.

Diabetic retinopathy, unfortunately, is a very insidious disease. It usually causes no symptoms in its earliest, most treatable stages, and by the time symptoms are noticed, many patients have experienced irreparable damage and/or loss of vision, and the overall prognosis is poorer. This is why dilated eye examinations by an experienced and knowledgeable eye doctor are so vital. The earlier retinopathy is detected, the more can be done to prevent, or at least delay, significant loss of vision.

The retina lines the inside surface of the eye, like wallpaper covering a wall. It has seven distinct layers, each with unique characteristics and functions, which are readily observable under a microscope. In the clinical setting (i.e. the eye doctor's office), the individual layers are not all directly observable, but a variety of examination tools and techniques, combined with intimate knowledge of retinal anatomy, allows the eye doctor to examine the layers damaged by diabetes, to make a diagnosis and evaluate the type and severity of diabetic retinopathy, and to make treatment recommendations. Such recommendations may include observation over time, improved blood sugar control, laser treatment of the retina, use of prescription medications, surgical treatment of the retina, or a combination of these.

The Normal Retina

The normal retina contains many blood vessels. Large arteries coming from the neck (the carotid arteries) branch off into smaller arteries serving the eye (the ophthalmic and ciliary arteries) which branch off into smaller arterioles coursing through and beneath the retina (retinal and uveal arteries, respectively) which branch off into thousands of microscopic capillaries designed to deliver blood to each bit of retinal tissue.

Diabetic retinopathy alters this normal anatomy and its function in several distinct steps or 'stages,' each of which has its own characteristics. The 'earlier' stages are less worrisome, but may progress to the vision-threatening, advanced stages unless something intervenes (whether that 'something' is better blood sugar control, blood pressure control, laser treatment, luck, or some other factors that have yet to be fully understood.) Here, we will consider the stages of retinopathy...

...Research has clearly shown that intensive diabetes management, including lowering blood glucose and blood pressure levels, greatly reduces the risk of getting diabetic retinopathy, and slows down its progression (worsening) in patients who do have it. In fact, the DCCT showed that a 10% reduction in HbA1c reduces the risk of retinopathy progression by 43%, while the UKPDS showed that better control of blood pressure reduced the risk of worsening retinopathy by up to 34%.

Many experts believe that retinal capillaries are damaged when blood glucose levels approach 180 mg/dl on a consistent basis (this is equivalent to a HbA1c of 8.0%.) This is why most guidelines recommend that patients strive to keep their average blood glucose at or under 150 mg/dl (equivalent to an HbA1c of 7.0% or less.) To achieve these targets, patients should perform regular home blood glucose tests and adjust their diet, exercise and medications accordingly. They should also work closely with their doctor to find the right medications and dosages, perform quarterly glycosylated hemoglobin tests, and monitor their blood pressure and blood lipids.

After having diabetes for 10 years, 60% of patients will have at least the beginning stages of retinopathy; after 20 years, that number jumps to more than 90%. This underscores the general rule that the longer a person has diabetes, the greater is the chance of having complications. The best way to detect diabetic retinopathy is through regular dilated retinal exams, the importance of which cannot be over-emphasized in early treatment and prevention of vision loss.

from Chapter 15 - Low Vision
Knowledge is Power, and a form of Cheap Insurance

Unfortunately, many people have already suffered the eye complications of diabetes. More tragically, many people will continue to suffer vision loss in spite of all we know, and the good news about prevention and effective treatments. Hopefully, far fewer diabetics will experience complications in the future. Hopefully, a definitive cure for diabetes is just 'around the bend.'

Until that time, though, it is very important that all diabetics know about what can be done, right now, to help them cope with vision loss. For those who have already experienced vision loss, this chapter may serve as a primer on what's available and how to get started. For those who haven't lost vision from diabetes, the information in this chapter might best be viewed as an 'insurance policy' of sorts; Hopefully, it will never be needed, but it will be nice to have some familiarity with this material, "just in case."

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