The chief complaint requiring a magnifier

Reading is the number one complaint of our low vision patients. Thankfully many forms of magnification can help in most cases in the form of traditional magnifiers. While this might not be the magic pair of eyeglasses that they were hoping for, restoring their vision and working distance to what it once was, it can be a necessary tool.

Magnifiers come in different varieties, hand held, stand or dome, with or without light, have a replaceable or rechargeable battery and now one even has a self-charging console. However finding the right magnifier for your patients’ needs and the proper amount of magnification is only half the battle. Many of our low vision patients often find them difficult to use, using improperly or unknowingly are using the wrong amount of power. Here are some magnifier tips that may help.

Type of Magnifier

The two most popular and main types of magnifiers we often use are either hand-held or stand magnifiers. If your patient has a hand tremor or difficulty holding a magnifier for a long period of time, suggest a stand magnifier. This will allow the patient to just rest the magnifier on the page. I know this seems like a no-brainer, but some patients just don’t know these exist as most over-the-counter magnifiers they see are hand-held.

Focus

Most of our patients think they should be using their reading glasses and or looking through their reading segment. However, this depends on the type of magnifier they are using.

Hand-Held Magnifiers have a focal-point that creates a real image and light-rays emerge parallel from the lens, so in this case, a person should use their distance correction when looking through the magnifier.   

Stand Magnifiers have a stand that is shorter than the lenses focal length, creating a virtual image, so rays of light emerging from the lens are divergent. In this case, the patient would want to be looking through the near portion of their glasses or use their reading glasses prescription.

I have seen however some preferences where this rule did not necessarily apply, but for that patient who is complaining of not being able to see clearly through a hand-held magnifier, and is most often looking through the near portion of their glasses, this may just do the trick.

Field of View

Many patients complain of the decreased field of view while using magnification, especially as they need higher powers. One little trick to increase their field of view is to have the patient move their eye closer to the magnifier.

Lighting

Lighting can increase acuity by as much as 25%. Many magnifiers have either LED or incandescent lighting. Some patients may have had a magnifier for years and the light is now either not working or dim and find it harder to use. I tend to prefer the LED lights. Some magnifiers also have a filter that can fit over the light for our patients who are light sensitive or prefer a color filter.

Diopters versus X Notation

It is important when prescribing a magnifier to note the dioptric value of the magnifier rather than the times amount of the magnification. The problem is that different manufacturers of magnifiers use different standards as their initial working distance (using 20cm instead of 40cm), so one companies 2X (5 Diopter) magnifier will not equal the same amount of power as another 2X (10 Diopter) magnifier by a different company.

So while a patient may think they are using the proper magnification determined (by X-notation), they might not be getting the exact power they need and using the wrong amount. Thankfully the diopters are usually written on the handle on most magnifiers, so a written prescription should always indicate the amount of diopters.

While many low vision patients will often be resistant at first to using a magnifier (which is a whole other discussion), they soon learn that when used correctly and implementing some of these tips it is a valuable tool.