Beyond Glasses and Contact Lenses Reading Solutions When You Are Losing Your Sight

By Scott Burge, OD

Maryland Eye Associates

. http://marylandeyeassociates.com

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Beyond Glasses and Contact Lenses Reading Solutions When You Are Losing Your Sight

Vision impairment means Best Correctable Visual Acuity (BCVA) is less than the familiar standard “20/20”. A healthy eye with normal vision will see 20/20 or better. Some people have perfect vision, so no “correction” is required. Others need correction with glasses or contacts to achieve 20/20 or better. These designations are simply letter sizes on eye charts viewed at a test distance of 20 feet.

Functionally, these letter size designations are a comparison of your vision to that of a “standard observer.” The standard observer has “normal” vision. If your vision is also normal (or correctable to the normal level), both of you see the same target at a test distance of 20 feet. Therefore, the designation 20/20 applies.

What does it mean if your level of best vision is 20/40? The standard observer with normal vision is now at a test distance of 40 feet, but you have to be at 20 feet in order to see the same object. If your level of best vision is 20/100, the standard observer is now at 100 feet, but you need to be at 20 feet to see the same thing. In other words five times closer.

If your BCVA is 20/200, the standard observer is now 200 feet away from the target, but you have to be at 20 feet to see it, (10 times closer). Conversely, if your level of best vision is 20/10, the standard observer is now at 10 feet, but you are further away at 20 feet, meaning that your vision exceeds the normal standard.

A patient with BCVA less than the normal standard of 20/20 has vision loss secondary to macular degeneration, diabetes, other disease or injury. Impairment becomes functionally significant when BCVA is 20/50 or worse. At this level, the term “low vision” is used by eye care providers. Vision solutions are beyond typical eyeglasses and contact lens prescriptions.

The most commonly prescribed low vision aids are hand magnifiers, ranging in power from 4X-8X. Usually they are only available through eye care providers. They are hand held, light weight and have long lasting LED bulbs. The size of the lens is inversely proportional to the magnification power. As magnification power increases, lens diameter decreases, which in turn reduces field of view.

Hand magnifiers are simple to use and cost effective. If BCVA is between 20/50 to 20/100, they are usually a first choice solution, except for patients with hand tremor conditions.

High Plus spectacles are another optical solution. Powers typically range from +6.00 to +20.00. As the power increases, the viewing distance at which reading material must be held decreases significantly. For example, a patient with BCVA of 20/100 will need 4 to 5 times more power than the person with 20/20 vision; in this case the solution is +10.00 glasses, but the focal length is only four inches, which is often unacceptable to the patient.

Numerous electronic magnification solutions are available given many technological advancements. A very effective solution is Amazon's Kindle reader with the ability to adjust font size. For the senior citizen, there may be a learning curve, but it is a wonderful cost effective reading aid.

Portable electronic hand magnifiers from Freedom Scientific (Ruby XL HD) and similar products from Enhanced Vision are excellent aids. Magnification power, lighting and background color can all be adjusted easily with the click of a button. Aids in this category usually have a price tag of less than $1,000. They are worth their higher cost, especially because higher magnification settings can be utilized if the patient's BCVA becomes worse.

Desktop electronic magnification includes computers and monitors from Apple and other computer companies, as well as low vision specific aids like Optelec's Clear View Plus. Large monitors, variable magnification controls, and high quality resolution are wonderful solutions from the technology age we live in.