The Dr. Bill Takeshita Foundation

Last Modified: Sat, 18 Aug 2007

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Diabetic retinopathy (DR) is a complication of diabetes mellitus and is the leading cause of blindness among adults over the age of 55 years. It affects males and females equally but African-Americans and Hispanics have a higher prevalence of diabetes and DR as compared to Caucasians. Diabetic retinopathy can lead to severe vision loss, including blurred sight, loss of peripheral and color vision, the early formation of cataracts and glaucoma, and detachment of the retina. In the early stages of the disease, patients may still have 20/20 sight. However, in the more advanced stages, DR can cause total blindness. Unfortunately, there is no cure for diabetic retinopathy but early diagnosis and treatment can prevent vision loss in as many as 90 percent of cases.

Diabetes mellitus is a medical condition that affects the manner by which blood is able to distribute oxygen to the tissues. Hemoglobin is a protein in the blood that grabs oxygen and later releases the oxygen to the tissues. In patients with diabetes, the hemoglobin does not release the oxygen normally and this deprives the tissues of oxygen. In addition, the blood tends to become agglutinated or thicker while the blood vessels become narrower, making it more difficult for blood to circulate through the body and distribute oxygen. Prolonged lack of oxygen tends to damage the body cells, including those of the eyes, kidneys, heart, feet, toes, and fingers. The lack of oxygen to the extremities cause symptoms of “tingling of the feet” and numbness.

In the early stages of diabetic retinopathy, small dot and blot hemorrhages develop in the periphery of the retina. This is called background diabetic retinopathy (BDR). The retina is the light sensing tissue located in the inside of the eye. It consists of millions of cone cells and rod cells. The cone cells are located in the center of the retina, similar to a “bull’s eye” on a dartboard. The cone cells provide detailed vision, color vision and daylight vision. The rod cells are located on the periphery of the retina and provide peripheral vision, the perception of movement, and night vision. Patients with BDR generally do not complain of blurred sight, poor color vision, or blind spots in their vision because these changes generally affect the rod cells in the peripheral retina.

In the more advanced stages of DR, the hemorrhages become more severe and affect both the peripheral and central retina. This dramatically affects the amount of oxygen that reaches the rod and cone cells. Retinal hemorrhages release a substance called vasogenic factors that stimulate the formation of new blood vessels in the eye. Unfortunately, these new blood vessels also bleed and release more vasogenic factors. This vicious cycle of new blood vessel growth is called proliferative diabetic retinopathy. When the new blood vessel growth occurs under the central portion of the retina, vision becomes very blurred, foggy, and distorted. Blood vessel growth in the front of the eye can cause blockage of the drainage system of the eye and lead to a condition called neovascular glaucoma. Patients with proliferative DR are at risk for developing retinal tears and detachments. The leaky blood vessels can stimulate the formation of scar tissue that attaches to the retina and pulls it off of its base. These retinal problems can lead to permanent loss of vision if not treated immediately.

Blindness due to diabetic retinopathy can be prevented. Routine eye examinations that include dilation of the pupils to examine the retina are extremely important for all patients with diabetes. Medications, exercise, diet, and daily measurement of blood sugar levels can control the blood glucose levels and minimize the progression of vision loss. Ophthalmologists who specialize in diabetes can perform specialized tests to determine the location of the hemorrhages in the retina and implement treatment to stop the bleeding. All patients with diabetic retinopathy will benefit from low vision optometry to design glasses and visual aids to improve the clarity of sight, reduce problems with glare, and improve contrast vision.

Recommendations

• All patients with diabetes must have yearly eye examinations with a dilated retinal examination.
• Patients with diabetes must measure their blood sugar levels daily and modify their dietary and exercise programs.
• A consultation by a low vision specialist and low vision aids can be extremely helpful to patients with diabetes. Specialized aids to help diabetics to measure their insulin and monitor their blood glucose can be prescribed.
• Patients should be evaluated for photochromic spectacles that may improve the clarity of sight, protect the eyes from the harmful rays of the sun, and reduce problems with glare. Photochromic spectacles will turn dark when exposed to sunlight and remain clear when indoors or during the evening. Glare sensitivity is one of the most common complaints of patients with diabetic retinopathy.
• Low vision aids such as bioptic glasses, hand held telescopes, and video magnification systems can improve distance sight to 20/20 while specialized reading glasses, hand magnifiers, and closed circuit televisions can allow patients to read small print, read medication labels, and see photographs.
• Students will benefit from being positioned in the front portion of the class with their backs facing windows, doors, and glare sources. The use of a black chalkboard and bold architecture chalk are generally easier to see than dry erase boards due to the glare created by the white board. In the event that a dry erase board must be used, it is very helpful to only use bold black dry erase markers rather than colored markers.
• Tinted paper with bold lines, bold felt pens, and thick pencils will help students to perform writing tasks at school. Students who are bothered by glare will also benefit from placing their paper on a dark blotter or dark piece of construction paper to help them to see the edges of their paper.
• Students will benefit from having copies of material normally written on the board or presented on overhead transparencies. If PowerPoint presentations are used, a dark background with white letters written in Arial or Tahoma will improve readability for students with low vision.
• At home, the use of an incandescent light bulb hidden behind a dark torchierre floor lamp can provide excellent general lighting while reducing glare. A small desk lamp such as an OTT full spectrum lamp may provide a soft light for reading and writing. See Lighting and Vision for more information on lighting.
• Computer users will benefit from changing the background of the display to a black or blue background with white letters. Enlargement of the font size will also increase readability. For information on how to modify the computer screen, see “Solutions To Help You User Your Computer.
• Students may benefit from using specialized computer software and technology such as Zoom Text magnification software, scanning programs such as Open Book and Kurzweil, and Video Magnification systems. For more information, see Computer and Assistive Technology for those with Low Vision.
• Specific low vision aids that are often helpful to patients with diabetic retinopathy include:
  • 4x to 6x bioptic spectacles
  • DVI clear image aspheric reading glasses
  • Prescription CPF, Transitions, Melanin, and NoIR filters
  • 4x to 6x aspheric hand magnifiers for reading fine print
  • ZoomText magnification software program can be very helpful for patients with low vision while JAWS and Open Book are helpful for those who cannot read print due to their vision problems.
• For more information, please see Low Vision Rehabilitation