I am happy and honored to introduce Dr. Chris Renner as a contributor to RetinaEyeDoctor.com! He and I practice closely together in Northern Virginia. I asked him to write about Low Vision. – “Randy”
What is Low Vision?
The great advances in treatment of eye disease have prevented many cases of blindness, however, many patients suffer partial visual loss and are left with reduced visual function. This limited level of vision, whether lack of visual clarity or loss of peripheral vision is called “low vision.” Common causes of low vision are macular degeneration, diabetic eye disease and stroke.
Low vision describes a decreased level of visual function and inability to perform the normal tasks of life even when you are wearing your best glasses. Maybe you have difficulty reading the newspaper or computer screen, or writing a check or reading your mail. A low vision evaluation can help you find the right tools to allow you to perform your normal daily activities.
A low vision evaluation and treatment will not improve your eye health or restore your sight. The goal is to restore function, the ability to perform the tasks in day-to-day life. I ask each low vision patient to list three activities that they are struggling with and we focus on improving their ability to complete those tasks. This might require special eyeglasses, magnifiers, aids or computer programs. Most patients have several different low vision “tools,” just like you might have several different screwdrivers in a toolbox. Most low vision devices help you by providing significant magnification.
The most powerful (and simplest) tool for allowing the patient with low vision to read is called a reading microscope. It is a special high-power pair of eyeglasses, possibly with prism, which allows you to see items approximately five times larger than usual. A reading microscope has the advantage of being relatively inexpensive, small and portable, and allows you to keep your hands free to hold whatever you are reading. The disadvantage is that you must hold your reading material approximately four inches from your nose and can read only a few words at a time. Reading microscopes are the most popular form of low vision device.
Other low vision devices include hand magnifiers, spotting telescopes, closed circuit television cameras, visual field expanders and computer software to magnify or read text on the computer. Each of these items can be extremely helpful in the right circumstances for the right patient. In Part 2 I will discuss hand magnifiers and telescopes.