By Bill Takeshita, O.D., F.A.A.O., F.C.O.V.D.
Low vision optometrists and ophthalmologists are doctors who design and prescribe specialized glasses and visual aids to help people with vision impairment to use their remaining vision maximally to read, write, and perform daily tasks. Nine out of every 10 people with vision impairment have functional vision that can be improved with optical and electronic visual aids. Unfortunately, many people with macular degeneration, diabetic retinopathy, glaucoma, and retinitis pigmentosa have not been referred to a low vision doctor for a low vision examination to be fit with specialized glasses. For millions of people with low vision who can no longer read with their magnifiers, low vision doctors can help them to read again.
A low vision examination is very different from a general eye examination. The purpose of the examination is not to inspect the tissues of the eyes again, but rather to determine ways to maximize the patient’s vision and provide solutions for the patient. The examination begins with the doctor speaking with the patient to understand the specifics about the desired goal. For example, if a pastor asks the doctor for help reading the Bible, the doctor must also spend time to know what size print is in the Bible, what distance the pastor will be holding the Bible from the eyes, what level of lighting is available, and other details so that he or she may customize a pair of glasses that will serve the pastor’s needs. Next, the doctor inspects the tissues of the eye and measures the central and peripheral vision to determine which region of the retina has the best function. For many people with macular degeneration, the central region of the retina often has scar tissue and the doctor will design glasses to help the patient use the peripheral regions of the retina. Conversely, for patients with glaucoma or retinitis pigmentosa, the peripheral vision is often reduced and the doctor will design visual aids to maximize the central vision.
A test called low vision refraction is performed to focus the light onto the desired region of the retina. Prism lenses and peripheral retinal locus (PRL) training may also be used to teach the patient how to use the healthier region of the retina to read. As simple as it sounds, it is often very difficult for people with low vision to do this on their own because they have used their eyes in a specific way for all of their life. To train a different region of the eye to read takes time and practice.
The low vision doctor performs many other tests to measure whether the patient can see some colors better than others, whether or not the patient can see faded print, and what levels of lighting maximize vision. Other tests are performed to determine the patient’s ability to move the eyes from left to right in a reading pattern, keep the eyes steady on the word being read, ability to focus the eyes together as a team, and the best distance to focus on the reading material. All of this information is used to design a pair of glasses that magnifies the print, increases the contrast, and deflects the words on the healthier regions of the eye for optimal reading.
One of the most common questions asked by patients is, “Can you make a pair of glasses that is the same power as my hand magnifying glass?” The answer is yes. Low vision optometrists and ophthalmologists can create specialized glasses that provide high levels of magnification that also incorporate the patient’s prescription needs. Colored tinted lenses can be used to increase the contrast of the print, helping people who have difficulty reading the gray ink on a newspaper more easily. Special anti-reflective coatings can be placed on the lenses to reduce glare and increase the brightness of the text while miniature telescopes can also be inserted into the lenses to help people to read at various distances. These telescopic glasses can be very helpful for musicians who have blurred vision and need to read sheet music from a distance of three feet. Glasses that used to look like “Coke bottles” can now be made thin and lightweight with excellent optics.
After the glasses have been designed, the doctor will teach the patient how to use the special reading glasses. This is a very important but overlooked step that is critical for successful reading. The patient must know whether to hold the print on his or her right or left side, what distance from the eyes, what type of light bulb to use, where to position the light, and how long to read each day. In some cases, the doctor will provide exercises to teach the patient how to use the healthiest region of the retina for reading.
People with more advanced or severe vision impairment will often benefit from using low vision glasses in conjunction with other visual aids. The combined use of reading glasses with magnifiers and electronic visual aids will allow many people with low vision to read again.
In summary, it is important for people with low vision to remember that specialized low vision glasses can improve the reading ability of the majority of people with vision impairment. Optometrists and ophthalmologists who specialize in low vision perform specialized tests to design glasses and visual aids to maximize the vision of people with low vision and can even help the legally blind to read.
After you’ve completed your eye exam with your physician, please have them complete Braille Institute’s Doctor Referral Form and then schedule a low vision appointment for additional low vision rehabilitation services at 1-800-BRAILLE (272-4553).