BY HOLLI W. HAYNIE

Dr. Warren Johnson reviews a patient's retina to determine changes in the optic nerve and eye tissue.

Imagine waking up and not being able to see clearly or having spots in your vision. The sense of sight is a precious commodity that people tend to take for granted until something goes wrong. Millions of Americans lose some of their vision every year, developing a condition referred to as low vision, and the numbers continue to climb as the population ages.

Normal changes can occur in our eyes and vision as we get older, but these changes don't usually lead to low vision. Low vision encompasses various levels of vision loss and is defined as partial sight or sight that isn't fully correctable with surgery, pharmaceuticals, contact lenses or glasses.

"It can include moderate vision impairment, such as tunnel vision or blind spots, legal blindness and almost total blindness, and may occur slowly or rapidly, depending on the cause," explained Warren Johnson, OD, medical optometrist at the Eyewear Gallery.

Low vision is typically the result of eye diseases and health conditions such as macular degeneration, cataract, glaucoma and diabetes and is most common among people over age 65. However, no one is necessarily exempt from losing vision because ultimately it depends on how well we care for our eyes.

"People assume they're getting their eyes better with new technology," Johnson said. "No corrective device or surgery is going to make up for the source of unhealthy vision or the vision that's going to be lost from damage."

Patients who undergo refractive surgery may assume they are forever cured and therefore don't need to visit the doctorm but Johnson warns the surgery can bring a false sense of security.

Medical optometry takes a different approach than that of standard optometry. The medical optometrist's goal is to preserve vision rather than simply correcting it. Johnson said he performs tests beyond normal vision screening such as screening the central 10 degrees of a patient's vision field and takes pictures of the back of the eye to check for beginning bleeding or a breakdown in pigment.

"I get MDs as patients all the time who don't realize the scope of medical optometry," said Johnson. "To me, taking care of people's eyes is more about teaching people how to preserve their vision, not just [telling them they] need a change in prescription levels."

The importance of preserving vision cannot be understated because millions of people have eye diseases they are unaware of until they begin to lose vision. For instance, it is estimated that three million people have glaucoma (a disease which elevates eye pressure, damaging the optic nerve), only half of which know it. Glaucoma is a silent disease and unfortunately people don't tend to notice tunnel vision sets in, and by then it's too late to regain lost vision.

Any noticeable change warrants a visit to an eye care professional who can determine if vision loss is a result of normal, age-related change or caused by a disease.

"Rapid change is always the most noticeable and often the most severe," Johnson maintained. "If the change is gradual or only in one eye, people may not immediately notice vision loss and let it go undetected."

Vision changes like blurriness, the inability to read street signs, lights that seem dimmer and difficulty in seeing up close can all be early warning signs, so it's important to have regular eye examinations. The earlier a problem is diagnosed, the better the chances of effective treatment and vision retention.

Johnson provides education about preventing vision loss through a healthy diet and the use of supplements. In 2001, the National Eye Institute (NEI) published results of a seven-year study, the Age-Related Eye Disease Study, which showed that a high-dose combination of vitamins C, E, beta-carotene and zinc significantly reduces the risk of developing advanced stages of age-related macular degeneration (AMD) by 25 percent. According to the NEI, these high levels of antioxidants and zinc are the first effective treatments to slow the progression of AMD.

Johnson recommends taking a multivitamin supplement with lutein, an antioxidant that is concentrated in the retina, and developing a diet that includes leafy green vegetables and fruits.

"Even if you have perfect vision, lack of a history of vision loss does not rule out the likelihood of you or a family member developing a vision disorder that cannot be treated with glasses or contacts," maintained Johnson, explaining that having poor eyesight doesn't necessarily preclude low vision, either. "Make a point to get an eye exam once a year and call your doctor if you notice any vision changes between visits."