The Low Vision Tool Box
Thomas I. Porter, O.D., FAAO
At a recent meeting, a new low vision practitioner asked me how many low vision aids the "average" low vision patient uses. What seemed like a simple question actually turned out to have a fairly complex answer.
Years ago one of my colleagues compared low aids to the tools used by a carpenter. A carpenter always has many tools in his toolbox. Each tool is designed for a certain job and he could never expect one tool to help with every task. In addition, the carpenter may not use every tool on every job or even on every day.
I have certainly found low vision aids to be similar to carpenter's tools in many respects. A good prescribing strategy is to break down low vision goals by the duration (time) of the task and the required working distance of the task. For instance, a long duration task such a reading a book or magazine may require a CCTV or some type of strong reading glasses. Very short tasks such as reading a menu, setting a thermostat or reading a price tag can often be accomplished with a small pocket magnifier. Intermediate duration tasks may be best accomplished with some type of stand magnifier. The importance of lighting to enhance contrast needs to be considered in your prescribing decisions. The working distance required dictates whether a goal can best be accomplished with a simple hand-held magnifying device, a telemicroscope, or a telescopic aid.
Never overlook the almost universal problem of increased glare sensitivity accompanied by lost contrast sensitivity. This dictates some type of filtered lenses to reduce glare and at the same time enhancing lost contrast. Unfortunately, in the past glare and contrast issues were often an afterthought by many low vision providers. By providing the appropriate filter a practitioner can dramatically enhance the mobility and safety of your patients.
In practice, multiple low vision aids are the rule, not the exception. Remember, a good low vision provider doesn't sell magnifiers, they help solve problems. To solve a patient's specific problem will always require having the right "tools" in the toolbox.