HEALTH & MEDICINE :: OCTOBER/NOVEMBER 2007
Treatment of Diabetes & Diabetic Retinopathy
Diabetes is a chronic disease that can be characterized by abnormal elevation of blood sugars due to the lack of the production of insulin or the inability of the body to utilize insulin properly. This disease can cause multiple complications especially if it is not well controlled. Complications can include things such as diabetic retinopathy, which can lead to blindness, kidney failure requiring dialysis, limb amputations from poor circulation, heart disease, hypertension, and diabetic neuropathy. The best way to avoid complications is to make sure blood sugars are kept under strict control.
Typically, diabetes is broken down into two types – Type I and Type II.
Type I is described as “Insulin dependent” in that patients usually are put on insulin immediately upon initial diagnosis. These patients are diagnosed earlier in life sometimes even in early childhood.
Type II is described as “Non-insulin dependent” in that patients usually are put on oral hypoglycemic agents (pills) in order to control blood sugars. These patients are diagnosed later in life, usually after age 30, and the disease is commonly associated with being over weight. This name can get confusing because many times Type II diabetics will also need insulin and therefore can be on both pills and insulin to control their blood sugars. Many times just losing weight will make the blood sugar control normal in a Type II patient.
Last, Type II diabetics can sometimes be “diet controlled”. This still means the patient is diabetic but their blood sugars are controlled with diet alone. These patients are susceptible to all the same complications as someone on oral medications or insulin for diabetes.
Specific treatment goals include setting a glycemic range for the patient to reach. The Diabetes Control and Complications Trial (DCCT) was a large nationwide study that showed the best way to avoid complications from diabetes is to keep blood sugars under strict control. The HgbA1C was the standard measurement of blood sugar control in the study and is still used today to determine the average blood sugar reading over a three month period. Most all diabetics should be getting this reading three to four times a year. It was found that the risk of development or progression of retinopathy (damage to the retina in the eye) or neuropathy (damage to the nerves in the body) is reduced by 50-75% by “intensive treatment regimens” when compared to “conventional treatment regimens.” The definition of “intensive treatment regimens” includes an HgbA1C < 7.0 % and fasting blood sugars between 80-120 mg/ dl. As a result of this study we now recommend that all diabetic patients try to achieve this level of control if possible. This goal is associated with a three times higher risk of severe hypoglycemia; therefore, patients must be very vigilant in monitoring their blood sugars to avoid hypoglycemic events.
Many patients ask what they can do to minimize their risk of needing laser or going blind. The one most important thing that they can do is check their blood sugars regularly, aim for a fasting blood sugar between 80-120 mg/dl and reach a HgbA1C level of <7.0% consistently. This goal is just as important as any of the other things that we can do as retina specialist to help treat diabetic retinopathy.
Other risk factors that can increase the risk of vision loss and the need for laser in a diabetic patient include elevated and poorly controlled blood pressure, elevated cholesterol, smoking, previous cataract surgery and the longer the duration of diabetes. If patients take good care of these other related medical problems, this can also decrease their risk of blindness significantly.
The definition of diabetic retinopathy is damage to the retina (the membrane that lines the back inside wall of the eye) caused by elevated blood sugars. Early changes are called non-proliferative diabetic retinopathy which usually is monitored. Damage can progress to proliferative diabetic retinopathy which increases the patients’ risk of hemorrhaging and severe vision loss. This is usually when laser is started. Early on, the patient may not have vision loss associated with diabetic retinopathy, but if left untreated ultimately they start to have visual symptoms such as blurriness and floaters. Diabetic macular edema is another common cause of vision loss in diabetics. This is when the macula, which is the part of the retina that controls central vision starts to swell because of leaky blood vessels. It can be compared to a sponge that is dry. Once the sponge gets wet, it swells. This causes the central vision to be blurry as it is difficult for light to focus on the macula once it is swollen. Macula edema is not the same thing as age-related macular degeneration which also affects the macula. It is important to know that all diabetic patients should have a dilated retina exam every year. Patients may have diabetic retinopathy before visual symptoms occur and will be much better off if they are diagnosed and treated before vision loss occurs.
Some treatments for diabetic retinopathy include focal laser for macular edema (swelling of the retina) and pan retinal photocoagulation for proliferative diabetic retinopathy (abnormal blood vessel that bleed easily). Laser treatments are very effective in reducing macular edema and proliferative diabetic retinopathy by 50%. Even though laser treatments are highly effective there are still many diabetic patients that still experience vision loss despite receiving laser. We now have new medications to inject around the eye (sub-Tenon’s injection) or into the eyeball itself (intravitreal injection) when laser is not enough.
The medications that are injected include steroids, Avastin®, Lucentis™, and Macugen®. It has been shown that steroids help reduce macular edema and therefore improve vision. Unfortunately, steroids can also increase the risk of cataract formation and glaucoma. Because of this, not everyone is a candidate for steroid treatment. Avastin®, Lucentis™ and Macugen® are all new types of drugs that reduce abnormal blood vessel growth. They can help treat both diabetic macular edema and proliferative diabetic retinopathy. These drugs have all been shown to be helpful in treating patients that have not responded completely to laser therapy.
Interestingly, despite the good results, they are all being used “off-label” which means the drugs were FDA approved for different reasons than diabetes. As a result many insurance companies do not pay for these new effective treatments. As these treatments become more standard of care, insurance companies most likely will begin to pay.
Last, sutureless 23 or 25 gauge pars plana vitrectomy surgeries are performed in an operating room setting to remove blood or scar tissue from the inside of the eye. Once this surgery required an overnight stay; now it is done in an out-patient setting and many times without the use of sutures.
In summary, there are many new exciting tools that we have as retina specialists to treat diabetic retinopathy. But the diabetic patient should know that the best way to prevent vision loss is through the control of their diabetes.
Paula C. Ko, MD is with Eye Physicians & Surgeons, P.A., 1207 North Scott Street, Wilmington, DE 19806. Dr. Ko graduated with honors from the Ohio State University College of Engineering in 1984. Dr. Ko received her M.D. degree from the Ohio State University College of Medicine in 1989, again with honors. Following her residency in Ophthalmology at Temple, Dr. Ko served a prestigious fellowship at Georgetown University in diseases of the retina and vitreous, and is Certified by the American Board of Ophthalmology.
Dr. Ko has an area of special expertise in retinal problems, especially diabetic eye disease, macular degeneration and retinal detachment. Dr. Ko has lectured extensively, and has published many papers on these topics. Dr. Ko has been named “Top Doc” by Delaware Today magazine for excellence in the field of Ophthalmology. Dr. Ko is at the forefront of ophthalmic technology, and utilizes the most advanced procedures, including laser treatment and intraocular injections, in the care of her patients.
For further information or to schedule an appointment please call 302-652-3353.
