Low Vision Problem in the Diabetic
Richard L. Windsor, O.D., F.A.A.O.
Laura K. Windsor, O.D., F.A.A.O.
Published in Vision Enhancement Journal
Diabetes is the leading cause of blindness in the United States for patients age 20 to 74. Diabetes can affect vision in a variety of ways. Vision loss occurs commonly from two major problems proliferative diabetic retinopathy and macular edema. Both are treatable with laser if detected early, but laser treatments may also create additional vision problems for the diabetic patient.
Visually impaired diabetics have specific needs to be addresses in the low vision examination. Diabetics must be able to see to fill insulin syringes and take oral medications. They need to see to test their blood sugar. Diabetics need to read labels on food containers to control their intake of carbohydrates. Diabetics, additionally, may have neuropathies affecting their feet. If the patient is unable to see his or her feet, care by their physician, podiatrist or family may be needed to monitor the health of their extremities. Glare and the loss of contrast sensitivity need to be addressed.
Diabetics often experience fluctuations in their vision related to changes in nearsightedness or farsightedness caused by ups and downs in their blood sugar. As blood sugar changes, the shape of the human crystalline lens changes. Before prescribing eyeglasses for a diabetic patient, doctors frequently retest the patient on another day to test for these fluctuations.
Loss of Central Sharp Vision
Macular edema is a swelling of the delicate macular tissue in the center of the retina. It does not cause total vision loss, but causes a loss of visual acuity. Macular edema can be treated with laser if identified in the early stages. Your optometrist or ophthalmologist can detect this swelling through a dilated retinal examination using a microscope and special lenses. Laser can reduce vision loss if caught in time. Vision loss caused by macular edema responds well to magnification.
Profound Loss of Vision
Proliferative diabetic retinopathy is the most visually threatening and dangerous condition a diabetic may have to deal with. It has the potential to cause profound vision loss by damaging the small blood vessels of the retina. Then chemicals are released from the retina that cause abnormal blood vessels to grow. These blood vessels break and bleed creating scar tissue within the eye. As the scar tissue contracts, it may pull on the retina leading to a retinal detachment. Laser treatment can reduce the risk of severe vision loss by 50%.
Color Vision Impairment
Color vision may be mildly affected along the yellow-blue axis.
Reduced Side Vision After Laser
Laser treatment is crucial in saving the sight of many diabetics. Laser, however, causes other visual problems that should be addressed by the low vision specialist. Pan-retinal photocoagulation laser treatments require hundreds of laser burns across the peripheral retina. By lasering these peripheral areas, more oxygen is available to the supply the crucial center of the retina, where our sharpest vision exists. Unfortunately, we must sacrifice part of the side vision to save the center vision. Night driving may become more difficult.
Loss of Contrast Sensitivity and Glare Problems
Patients often describe a “hazy-glare” after laser surgery. Contrast sensitivity, the ability to judge subtle differences in images. Our world is one of subtle contrasts. We use contrast sensitivity to see faces or find a dark object on a darker background. Amber filters like the Corning CPF series reduce the glare and may aid contrast.
Night Blindness After Laser
The peripheral retina contains more of the rod cells that we use to see at night. Thus in lasering the peripheral retina, we lose more rod cells that we need to see with at night. At night, clear lenses may be required. If extensive laser has been performed, night driving may become dangerous. Milder forms of laser called focal laser, may increase glare, but have less effect on the peripheral vision and not decrease night vision as dramatically.
Abnormal blood vessels may also grow into the front portion of the eye causing a severe painful glaucoma. This form of glaucoma can be prevented by timely laser treatment of the retina. But once this type of glaucoma is established, it is very difficult to control and can lead to profound vision loss.
Diabetics develop cataracts at a much earlier age than non-diabetics. Cataracts may also occur in young diabetic children. Cataracts cause a fogginess or clouding of vision. Additionally, glare outdoors and from oncoming headlights may become worse.
Diplopia or Double Vision
An occasional complication that diabetics may have is double vision. This is caused by a paralysis of one of the six muscles in control eye movements. Double vision is very bothersome to the patient, but it often resolves over several weeks to months.
The key to diabetic vision loss is to prevent it through early detection and treatment. Diabetes can have a vast range of vision problems. Once vision loss occurs, the low vision specialist can aid the diabetic cope with many of these problems.
Related Links on Diabetic Retinopathy
National Eye Institute on Diabetic RetinopathyThis pamphlet has been written to help people with diabetic retinopathy and their families and friends better understand the disease. It describes the cause, symptoms, diagnosis, and treatment of diabetic retinopathy.
Joslin Diabetes Center- Information on diabetes, diet, exercise, diabetes medications and diabetes gmanagement
Diabetic Site from England An excellent site on diabetic retinopathy.
Screening for Diabetic Retinopathy
Eyes On Diabetes Australlia Eyes on diabetes is an online resource for diabetic retinopathy in Australia. This site has been developed by the Eyes on Diabetes Forum for use by Health Professionals, People with Diabetes, Carers and the Wider Community