|A healthy diet, along with regularly testing blood sugars, can help diabetics ward against diabetic retinopathy.|
|Lucentis by Genentech contains an anti-body that binds to and removes extra vascular endothelial growth factor.|
|Anti-VEGF intraocular injections, such as Regeneron Pharmaceuticals, Inc.’s Eylea, are one way to treat diabetic retinopathy.|
Tips for optometric assistants and technicians on how to improve their instrumentation skills.
Diabetes is a disease in which the body doesn’t manufacture insulin. This hormone is produced by the pancreas which allows sugar to pass from the blood into the cells. Also known as glucose, the hormone is an important energy source for the body.
In a healthy person, the presence of insulin is invaluable in passing glucose onto the cells. The body works to keep a constant supply of glucose for the cells. However, if there is too much glucose, the body stores the excess in the liver and muscles. If there is not enough glucose, the body is stimulated to eat.
If the pancreas produces too little insulin or none at all, the glucose will build up in the blood and will eventually pass out of the body during urination. This action causes the body to lose its main source of fuel. There are two types of diabetes. In Type 1, also known as juvenile diabetes, the pancreas makes little or no insulin. This situation is caused by the immune system destroying the cells in the pancreas that manufacture insulin.
With Type 2, once known as adult onset diabetes, there’s a buildup of sugar in the bloodstream. This buildup occurs when insulin is not used properly by the body. The excess sugar in the blood affects the blood vessels all over the body, and damages the kidney, nerves, and eyes.
Over time, if diabetes is not controlled it causes damage to the blood vessels of the retina and also can affect the lens of the eye. When there is prolonged elevated blood sugar, an accumulation of fluid occurs in the natural lens of the eye, affecting the vision. Elevated blood sugar can also cause swelling of the retinal tissue and damage to the tiny blood vessels that nourish the retina. This damage is called diabetic retinopathy.
STAGES OF DIABETIC RETINOPATHY
NPDR: Non-Proliferative Diabetic Retinopathy: This early stage of retinopathy usually does not have any visual symptoms. It is characterized by the presence of “dot” and “blot” hemorrhages and “microaneurisms.” Microaneurisms are tiny swelled bulges that form in the blood vessels which can leak fluid and blood into the retina. The fluid leakage is caused by excess sugar in the blood which blocks the vessels and thereby cuts off nourishment to the retina, resulting in vision loss. The resultant fluid can leak into the macula and cause it to swell and blur the vision (macular edema). Macular edema can cause difficulty with reading or doing close work. Usually non-proliferative diabetic retinopathy does not require treatment unless it progresses.
PDR: Proliferative Diabetic Retinopathy: This is the more advanced form of diabetic retinopathy. Because of the decreased circulation of the retinal blood vessels and lack of nourishment, abnormal blood vessels begin to grow. The abnormal blood vessel growth is called neovascularization. Due to the blood vessels fragile nature, bleeding can occur and subsequently cause scarring of the retina. As the scar tissue forms, it can pull and detach the retina. The blood that has leaked from the retina can sometimes been seen by the patient as “strings” or “floaters” in front of the vision. The proteins leaking from the blood vessels can form hard exudates. The new blood vessels may also grow on the iris and can lead to elevated intraocular pressure, known as neovascular glaucoma.
A full comprehensive eye and dilated exam is needed to diagnose if a patient has diabetic retinopathy. Special attention should be paid to the retina and macula for swelling and fluid accumulation.
After the dilated exam, an OCT (Optical Coherence Tomography) can be performed. This test uses light projected onto the retina which is reflected back and provides a cross-sectional view of the retina and its layers. Leakage and swelling can also be seen by fluorescein angiography, which involves injection of a fluorescent dye into the bloodstream. The passage of the dye is documented by photographing the retina using a camera with specialized filters which highlight the areas of fluid leakage and swelling. This test can aid in determining the progression of the disease, and indicate the source of leakage.
Treatment of diabetic retinopathy can vary depending on the extent of the disease in the patient. A laser is applied to seal the areas of the retina with abnormal blood vessels which can leak fluid and blood into the retina.
For early stages of NPDR, the physician may recommend regular checkups to monitor the retina, as well as diet, exercise, and good blood sugar control. For more advanced stages of PDR, the ECP may recommend pan-retinal photocoagulation. This method applies numerous laser marks across the retina in order to shrink and cauterize the abnormal blood vessels and tissue. Laser surgery may need to be repeated several times.
If there is a vitreous hemorrhage present, the ECP may not be able to see the source of the bleeding. Therefore, a vitrectomy may need to be performed. This procedure involves removing the vitreous from the eye, and replacing it with a clear salt solution, and thus allows the physician to have clear media to look through in order to perform the laser treatment.
Recently Anti-VEGF intraocular injection has become another form of treatment for diabetic retinopathy. Medications such as Lucentis‘ (by Genentech), Avastin‘, (also by Genentech), and Eylea‘ (Regeneron Pharmaceuticals, Inc.) are injected into the back of the eye and contain an antibody that binds to and removes extra VEGF (Vascular Endothelial Growth Factor). VEGF is a chemical that stimulates the growth of new abnormal blood vessels which easily bleed and can pull on the retina causing retinal detachment.
The longer that a patient has diabetes, the greater the risk she will have of developing diabetic retinopathy. Patients with poorly controlled blood sugar levels or high blood pressure have a higher risk factor. Kidney disease, smoking, pregnancy, obesity, and elevated cholesterol levels are also contributing factors. In addition, Hispanics and African-Americans are at greater risk.
There are usually no symptoms with the early stages of diabetic retinopathy. As the disease progresses, patients may experience the following:
- Blurry vision
- Eye pain
- Fluctuating vision
- Dark spots or strings floating in front of vision (floaters)
- Changes in color vision
- Missing or veiled areas of the field of vision
Those patients who practice having a healthy diet, lose weight if needed, exercise regularly, and maintain good control of their blood sugar, blood pressure, and cholesterol will be less likely to develop diabetic retinopathy. Even if the patient already has diabetic retinopathy, this health regimen can help a long way towards preventing more serious developments.
Janet Hunter is president of Eye Source LLC, and specializes in ophthalmic technician training.
WHERE TO FIND IT:
Genentech •800-821-8590 •gene.com
Regeneron Pharmaceuticals, Inc. •855-734-3648 •regeneron.com