Eye strain is prevalent among college students, and classrooms might be partially to blame, said one local optometrist.

Carrie Koenig, an optometrist at McFarland Eye Center, 1128 Duff Ave., said she thinks college students are more easily susceptible to eye strain “because college students are doing a lot of reading and focused work.”

Malhar Gor‚, a staff physician at the Student Health Center, said eye strain is not necessarily prevalent just among students, but also in people who look at computer screens or into microscopes.

According to AudioHealth Web site, at www.yourhealth.com, eye strain has three main causes: first, having the eyes focused on a fixed object that is close to the eyes for an extended period of time, second, poor lighting, and third, glare.

Koenig said eye strain occurs when eyes focus too much on one thing for extended periods of time.

She compared focusing the eyes on an object for a long period of time to lifting weights. Muscles get tired, and they can only be contracted for so long.

Eyes are designed to shift focus from objects that are near to those that are far away, she said.

“Your body wasn’t made to focus for long periods of time,” Koenig said. “It involves a muscle’s contraction to maintain that focus.”

According to www.betterbodz.com, eye strain happens when the muscles tighten after doing a task such as reading, working at the computer or watching television for an extended period of time.

The eyes will become irritated, dry and uncomfortable.

Gor‚ said the dryness comes from not blinking. The eyes remain open when they are fixed on something, he said.

“If you don’t blink, you don’t get proper lubrication of the surface,” he said.

Focusing for long periods of time can also cause back and neck pains, which are the result of leaning forward to focus on something.

“Your posture is affected by your wanting to see something,” Gor‚ said. “You become so involved, [your posture] is not noticeable until you stop.”

Poor lighting while reading or doing close work also causes eye strain.

Gor‚ said that the iris and the lens work together to clarify what you are seeing. The iris controls the amount of light that is let in to the eye and the lens focuses the images.

There has to be a balance between these two things, he said. If the iris allows too much or too little light into the eye, the lens can’t focus the object.

Koenig said contrast helps the eyes to focus.

Little or no contrast is “stressful on the visual system,” she said. Printed materials have better contrast for a person’s eyes than a computer or TV screen.

“Letters fade around the edges on a computer screen,” Koenig said. “The focusing system has trouble judging because there are no boundaries.”

Another cause of eye strain is glare, which occurs when light reflects off an object. Shadows form on what you are trying to look at, and then the muscles around your eyes tighten so you can try to focus the object you are seeing.

Eye strain can be prevented or relieved by following a few simple tips.

Koenig said light sources should be below the line of sight to prevent glare and the light should focus on the reading.

“You do not want to have a window behind the computer or yourself because the light would go directly into your eyes or be reflected off the screen,” she said.

Light going right into the eyes leads to squinting, which can cause muscle tension, Koenig said.

“You want the light in the room to be dim, but not dark” when looking at a computer or TV screen, Koenig said, because you want contrast, just not too much or too little.

Not all of a student’s eye strain may be the student’s fault, however. Classroom settings may also be partially to blame.

Most classrooms have fluorescent lights located above people and are not too bright or too dark. However, fluorescent lights are not an ideal light source, Koenig said.

“Fluorescent lights aren’t focused on what you are reading and they have flicker frequency,” Koenig said. Flicker frequencies vary from room to room, she said.

Koenig said that fluorescent lights also tend to cause more glare.

Some professors also use PowerPoint presentations that have print and images that are blurry around the edges and make it hard for the eyes to focus.

Koenig said she recommends taking breaks every 15 minutes to look off into the distance and shift the focus to avoid strain.

Some signs of eye strain include headaches, blurred vision, pain or soreness around the eyeball, red and watery eyes, dry eyes that feel scratchy, tired or aching heaviness of the eyelids or forehead and backaches and neck aches.

Gor‚ said eye strain is something that you “don’t need to see a physician for all the time.”

However, Koenig said eye strain is the most common symptom for refractive error eye problems, such as near- or far-sightedness. It’s therefore important to have an eye exam to make sure it is not something that may need to be corrected with glasses or contacts.

Koenig said people who are between the ages of 18 and 65 should have an eye exam done every two years.