The Dr. Bill Takeshita Foundation

Last Modified: Sat, 18 Aug 2007

View other Common Causes of Vision Impairment

Macular degeneration is a disease of the retina and is one of the leading causes of vision impairment in the world today. The retina is the light sensing tissue that lines the inside of the eye. It consists of millions of cells that absorb light and send information to the visual centers of the brain. The centermost region of the retina is called the macula and consists of cone cells that provide detailed sight, daylight vision, and color vision. The macula geographically accounts for less than 10 percent of the entire retina, similar to a “bull’s eye” on a dartboard. However, this small region of retina plays an extremely important role because it allows us to identify details and provides clear sight, stereoscopic depth perception, and distance vision. The remainder of the retina that surrounds the macula consists of rod cells which are responsible for night vision, and peripheral vision, but they do not have the ability to see details clearly.

Patients with macular degeneration tend to have blurred distance and near sight, sensitivity to glare and bright light, poor contrast vision, reduced stereoscopic depth perception, and they may have color vision problems. Their clarity of sight may range from 20/70 in the early stages but may worsen to 20/400 in the most advanced stages. Fortunately, patients with macular degeneration do not become totally blind because the condition only affects the macular region and does not affect the peripheral retina. Patients with macular degeneration tend to use their peripheral vision to perform visual tasks and the use of low vision aids can magnify the images to a level that allows the rod cells to identify details.

Age related macular degeneration (AMD) is the leading cause of legal blindness among adults over the age of 65 years of age. AMD is more common among smokers and those of Scandinavian descent or those with blond hair and blue eyes. It is thought that the reduced amount of pigment called melanin does not provide those with fair colored skin and eyes with sufficient protection from the harmful rays of the sun. For these reasons, it is strongly recommended that those with a family history of AMD stop smoking and wear protective filters when outdoors to filter the short wavelength solar radiation.

Dry AMD is the most common form of age related macular degeneration. It primarily affects the cone cells of the macular region and does not cause the leakage of blood or other fluid around the macula. The visual acuity tends to range from 20/70 to 20/200. The rate of progression of the disease is relatively slow. There is no medical treatment for dry AMD but vitamin therapy has been reported to slow the progression of the disease. Low vision aids and specialized glasses are very effective in improving reading sight, reducing problems with glare, and protecting the eyes from the harmful rays of the sun. Many patients with dry AMD are able to continue to drive with the use of specialized bioptic glasses.

Wet age related macular degeneration (WAMD) is a more complicated form of AMD in which the blood vessels under the macula leak and later grow abnormal new vessels. The leakage of blood under the macula causes swelling and the normally flat retina is elevated, causing straight lines to appear wavy and distorted. The visual acuity may be as good as 20/70 but may quickly deteriorate to 20/400 as the hemorrhages underneath the macula enlarge. Continued leakage of blood under the macula can cause blind spots in the central vision and patients may be forced to look off to the side in order to see details of objects more clearly.

Wet macular degeneration is treated with the use of specialized tests to determine the location of the hemorrhage. The use of fluorescein dye injected in the arm can determine the location of the hemorrhage and laser, photodynamic therapy, and other medications are used to stop the leakage of blood or to prevent the formation of additional blood vessels under the macula.

Juvenile macular degeneration is the term used to describe cases where macular degeneration affects the eyes of children and young adults There are many different forms of juvenile macular degeneration including Best’s disease, fundus flava maculata, cone degeneration, and Stargardt’s disease. Blurred distance and near sight, sensitivity to glare and bright light, blind spots in the central field of vision, and reduced depth perception are common symptoms. Similar to age related macular degeneration, there are no cures for these diseases but children and young adults respond extremely well to low vision rehabilitation.

Recommendations

• Children and adults with macular degeneration should be followed by an ophthalmologist who specializes in diseases of the retina and vitreous. Specific tests and treatments can be performed to slow the progression of the condition.
• A consultation by a low vision specialist and low vision aids are recommended to improve the usable vision of patients with macular degeneration.
• Patients should avoid smoking, wear specialized filters to protect their eyes from the sun, and take vitamins to preserve their vision. Consult with your eye care professionals regarding vitamin therapy.
• Low vision aids such as bioptic glasses, handheld 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. For more information, please see Computer and Assistive Technology.
• 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.
• Macular degeneration affects distance sight significantly. 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 typed in Arial or Tahoma fonts will improve readability for students with low vision.
• Students may have some difficulty seeing small objects such as a baseball while standing in the outfield. They may also have difficulty seeing in the direct sunlight and may prefer to wear their sunglasses and a hat. Students will benefit from additional time to adapt to the indoor lighting after entering the classroom from lunch or recess. Sports such as soccer, basketball, gymnastics, swimming, and golf may be easier to participate in rather than baseball or tennis.
• 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 Use 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.
• Potential drivers should have an examination by a low vision specialist to determine whether bioptic glasses will provide sufficient sight to take the drivers test.
• Patients with macular degeneration should test their vision daily with an Amsler Grid Test. Consult with your eye care professional regarding how to perform this easy test.
• Specific low vision aids that are often helpful to patients with macular degeneration include:
  • 4x to 6x bioptic spectacles
  • DVI clear image aspheric reading glasses
  • Prescription CPF, Transitions, Melanin, and NoIR filters.
  • 4x to 10x aspheric illuminated halogen or LED stand and hand magnifiers.
  • ZoomText magnification software will allow computer users to read and listen to the text on the computer screen. For those with early dry AMD, see Solutions to Help You Use Your Computer.
  • Electronic video magnification systems can greatly improve readability of mail, newspaper, bible, and magazines.
  • Direct halogen spot lighting can improve visual function in the kitchen and in the study room.
• For more information, please see Low Vision Rehabilitation