The Dr. Bill Takeshita Foundation

Last Modified: Sat, 18 Aug 2007

View other Common Causes of Vision Impairment

Accommodation is the ability to change the focus of the eyes from one distance to another. It is one of the most important visual skills used by students in the classroom and on the playground. Students with poor accommodation may suffer from blurred sight, headaches, eyestrain, and poor eye-hand coordination. Teachers and parents may be able to detect accommodative dysfunction when their students and children have difficulty copying from the chalkboard to their paper or if their reading accuracy deteriorates with time.

Accommodation is a neuro-muscular function that is controlled by cranial nerve III that is located in the brain stem. This nerve sends a signal to a muscle in the eye called the ciliary muscle. When the ciliary muscle constricts, the shape of the crystalline lens thickens, allowing the eye to focus on near objects. Conversely, when the ciliary muscle relaxes,the crystalline lens becomes thinner and the eye focuses on distant objects. Children and adults with accommodative dysfunction do not have the ability to quickly focus from one distance to another and their eyes work similar to a video camera that does not have auto-focus.

Children normally have very strong accommodative focusing skills. This allows them to hold toys, pictures, books, and other objects very close to their eyes and see them in clear focus. However, for some children, accommodative focusing skills do not develop normally due to delayed development of the ciliary muscle, trauma, medications, and even the lack of use of the eyes. These children may have 20/20 eyesight and may be able to read the smallest letter on the eye chart. However, they do not have the ability to shift the focus from the eye chart to their reading materials for sustained periods of time. Reading glasses and eye exercises can be very effective in correcting blurred sight, headaches, and eyestrain due to accommodative focusing problems.

Adults will generally experience accommodative focusing problems as they age. This is because the focusing ability of the eye deteriorates with age, especially after the age of 40 years. College students may notice that their distance sight is blurred after reading for prolonged periods of time. Computer users may suffer from eyestrain while adults over 40 years find themselves holding their reading materials farther or they need bifocals, magnifiers, and reading glasses to read small print. This deterioration of accommodative focusing skills among adults is a normal condition and is called presbyopia. Focusing eye exercises can slow the progression of presbyopia but does not cure the problem after the age of 50 years. Reading glasses and contact lenses are recommended to help those adults who have blurred sight, headaches, and eyestrain due to accommodation problems.

Recommendations

• Use additional lighting when reading, writing, and performing deskwork. The added illumination will help the eyes to focus more easily
• Low powered reading glasses can provide sufficient help to help the eye to see. Try not to purchase over-the-counter magnifiers and reading glasses, which may be too strong for your eyes. The use of magnifiers and reading glasses that are too strong will make your eye dependent on these magnifiers, thus reducing your accommodative focusing skills. Consult with your eye doctor for a precise prescription.
• Students with accommodative focusing problems will benefit from having additional time to complete activities that involve copying from the chalkboard to their paper.
• Consult with a developmental optometrist for specific accommodative focusing exercises
• For more information, please see Low Vision Rehabilitation