What is low vision?

The American Academy of Ophthalmology defines low vision as vision loss that cannot be corrected by medical or surgical treatments or conventional eyeglasses. A person with low vision often is told that there is nothing more that can be done for their vision. A low vision optometrist's role is to assist a low vision patient in maximizing their remaining vision through education, resources, low vision devices, and special optics.

What is the importance of knowing the patient's goals?

One of the first things a patient will be asked when they come in for a low vision examination is what their goals are. It can be watching television or reading a book, seeing a pastor at church or watching someone walk across the stage. Hence, based on the patient's goals, the low vision optometrist can best guide the patient on what devices and optical aids will help them achieve those goals.

Most low vision devices and optics are meant for a specific goal, for example magnifying glasses may work for short time periods of reading, but will not assist a patient in watching television.

• Full diameter microscopes - An example shown in the video above is a 2x full diameter microscope. These custom glasses would help someone at closer range. This one has a very large field of view, and it has no distortion at the edges of the microscope. However, with a fixed focus lens, it is only going to be good for when someone is sitting and reading something up close, and they would have to remove the lenses before they got up and moved around. In 6x microscopes, you'll get a lot more magnification, but you'll still get the same wide field of view. These would also not be suitable for mobility purposes, but only for sitting and reading.
• Telescopes - The use of microscopes and prism readers will be mainly for up close tasks, while telescopes will be used for distance magnifying. These telescopes typically come in Galilean or Keplerian models.
  • Keplerian telescopes are focusable, have a wider field of view, are heavier and longer than Galilean telescopes.
  • Galilean telescopes (full diameter) are fixed, lighter and smaller than Kepler models. They provide a narrower field of view and are perfect for viewing long distances.
• Prism readers - Prismatic readers would solve the mobility problem. Prism readers have a higher magnification power. They usually start at +4 and can go up to +12. When magnification reaches this level, a base in prism is prescribed. Essentially, the prism relieves the strain on the eyes caused by the patient holding the material so close to their face. A base in prism  is important because for magnification like this, the working distance has to become closer and holding the object closer can strain the eyes because they have to converge or cross together more.

What are the benefits of hands-free devices?

Hands-free devices have many advantages:

• When you are doing routine activities such as driving, holding a phone, eating, mowing the lawn, or solving a puzzle, having your hands free is very important.
• Older or disabled people may have difficulties holding objects steady for a prolonged period of time.
• A hand-held device may make certain activities difficult, such as reading a paperback book on the train, reaching for an item in the supermarket, or shooting a basketball at the free-throw line.

Scheduling a Low Vision Exam

Before a patient is shown a device it is important for a low vision optometrist to fully understand the patient's vision and goals. Armed with that information the low vision optometrist can help guide the patient on the best devices for their needs and budget. We are fortunate to have the technology and products to maximize vision for so many patients. We welcome you to schedule a low vision exam at our Chattanooga office.