Contrast Important for Those with Vision Problems
May 23, 2000 -- It often begins as a small distortion in the center of the
field of vision. As it progresses, this area gets larger and larger until it
becomes hard to see things right in front of you. More than 13 million people
are affected by macular degeneration, which is the leading cause of legal
blindness in those over 50.
The macula is the part of the eye that lets us see fine detail at the center
of our field of vision. When problems occur in this area, things in the middle
of the field of vision become blurred, while our ability to see at the edges
remains. This leads to problems with driving, recognizing people at a distance,
and other sight-related tasks. Being unable to read is usually the worst
Charlotte A. Hazel and colleagues from the Vision Science Research Institute
in England recently looked at how vision relates to quality of life for those
people with macular disease. Twenty-eight patients were given a comprehensive
assessment of how well their eyes were functioning. This was followed by a
questionnaire that asked them about such quality of life issues as their
ability to get around, read, and participate in leisure activities.
"Reading performance is strongly associated with vision-related quality
of life," write Hazel and her group in the journal Investigative
Ophthalmology and Visual Science. "The impact that reading ability has
on these patient's overall opinion of their vision is understandable when
considering the importance of an intact central visual field on tasks such as
reading, and the importance of these tasks in daily life."
Bright lights increase the contrast between the page and the writing, which
makes it easier to read numbers and letters. The research by Hazel and her
colleagues showed that contrast might be even more important than print size in
Many low-vision aids, such as hand-held magnifying glasses, combine
magnification and bright lights to help the person see. Special telescopes may
be used to see things far off. Higher-tech solutions include using big and bold
type on a computer or using closed circuit TV cameras to project the words onto
Other useful devices include watches and timers with big numbers,
attachments to phones that allow a person to see better so they can dial, and
large print books. Many calculators and similar devices have been "taught
how to talk."
"Contrast sensitivity seems to be important in these patients, and
therefore has implications on the design of reading materials," they write.
"Consideration should be given by manufacturers when labeling products so
that maximum word visibility can be obtained."
Albert O. Edwards, MD, an ophthalmologist at the University of Texas
Southwestern Medical Center in Dallas, tells WebMD the study highlights the
importance of contrast when communicating with those who have macular problems.
For instance, people going to the supermarket may take along a flashlight, in
addition to a magnifying glass, to get more contrast between the paper and the
letters on cans or other packaging.