Magnifying print to make it easier to read for individuals with central vision loss from macular degeneration and other visual disorders can be accomplished using strong reading glasses and magnifiers. Unfortunately both of these techniques require the user to hold the material very close which makes it uncomfortable and fatiguing. The only optical option available to provide magnification at more normal working distances are telescopes focused for near.
Telescopes can either be focusable or fixed focus for the desired working distance. As telescopes get stronger in power their fields of view become narrower. Fortunately the field of view of telescopes is like a cone—the further away you are from the material the more you can see at once. Galilean telescope can provide an ample field of view up to approximately 2x power, while Keplerian telescopes provide wider fields of view when powers above 3x are required.
We suggest the following steps to maximize your ability to read with a bioptic telescope:
- Maintain the furthest distance possible from the material you want to read. You might find it helpful to place the material on a reading stand to keep it upright—it can be further than arm’s reach as you can lean in to turn the page when necessary. Make certain the reading material is well illuminated.
- Position the telescope in front of your preferred seeing eye.
- Focus the telescope for the working distance determined in step #1.
- Determine whether the telescope provides enough magnification for you to read the material fluently.
- If you can read it well, try moving further away (while refocusing) to gain a wider field of view.
- If you cannot read it well, try adding more light and/or moving in closer (while refocusing).
Some other hints
- A binocular device may be able to provide a wider field of view, however you need to determine the most promising working distance first so that the binocular telescopes can be aligned for that distance.
- Determine whether the print will be at eye-level or lower down. This will help determine the proper positioning of the telescope in the frame.
- No matter how wide the field of view can be achieved, it will only cover a few inches across the line. With practice you will learn to move your head and eyes together to track along the page.