Some Napa children considered slow learners may actually suffer from a hidden disability -- poor vision.

That's the warning from Napa Valley optometrists, who say eye problems can limit children's ability to read, causing otherwise smart kids to struggle with schoolwork. Worse yet, they may be misdiagnosed as having attention deficit disorder or hyperactivity.

Napa optometrist Dr. Randall Cummings recalls the case of a second-grade boy brought to his office last spring. School officials were planning to hold him back a year.

"We started over the summer doing ... eye exercises," he said. "I worked with him for about eight months."

He said doctors thought the boy was hyperactive. "They had even started him on Ritalin," he said. "Now, his mother tells me he's at the top of his class and he's no longer hyperactive."

"It's good news to find these things, because they are treatable," he said.

Sight and vision are not synonymous. A child can have 20/20 eyesight but poor vision, which can go undetected for a lifetime, according to the Optometric Extension Program Foundation. "Vision ... is the ability to understand what we see, and it is a learned process," according to the foundation. Some children, for example, don't learn how to use both eyes simultaneously for more than a brief period of time, causing them, when reading, to miss words, phrases or entire chunks of paragraphs.

As many as two out of five youngsters struggle in kindergarten, first and second grades, and the problem may simply be related to their eyes, Cummings said.

"They have good screening in the schools here, but it is basic," he said. "Learning problems caused by vision are not always detected, but I commend school nurses for doing a good job."

Cummings said children are sometimes assumed to be hyperactive or just plain lazy. "They are put in a category, labeled and stuck with that," he said.

Developing vision

A few states require comprehensive eye tests, but California's eye testing is not nearly as rigorous, according to Dr. Matthew Hileman of the St. Helena Optometry Group.

"If a learning disability is suspected, or school performance is out of line with what (parents) think intelligence is, or if there are questions regarding performance of a kid at school who is not doing as well as he or she should, sometimes it's the eyes," he said.

Hileman, who also teaches at UC Berkeley's School of Optometry, said the most common eye problem he sees is the inability for both eyes to coordinate as they should with each other. The pairing of both eyes is known as binocular vision. Far-sightedness is also common, he said.

The Calistoga eye doctor earned his degree in optometry from UC Berkeley and opened the St. Helena practice four years ago.

Hileman works closely with the InfantSEE program, a public health program designed to promote eye and vision care for infants.

According to InfantSEE's Web site, "Cooing, sitting up and crawling are signs that your baby is growing. Your baby's vision has stages of development too, but usually there are no signs to mark the progress."

"Far sightedness ... is the No. 1 thing I see," Hileman said. Parents should look for symptoms, including headaches, but early testing is crucial.

'Lazy eye'

"We want to see parents get kids in for full eye examinations around pre-school or by kindergarten," said Dr. Jean Neeley, an optometrist in Calistoga. "If they have 'lazy eye,' it can be corrected," she said.

"Lazy Eye," or amblyopia, usually affects just one eye and occurs when the brain does not fully acknowledge the image from that eye. It is not correctable by glasses or contact lenses.

She recommends eye exams before a child's first birthday, and said pediatricians in the valley are good at picking up visual problems.

Many eye problems can slow a child's learning, she said. Blurred or distorted vision and eye muscle coordination can lead to poor reading ability.

Symptoms to watch for include excessive head movement while reading. Transposition of words can be the result of an eye problem or dyslexia. Sometimes a chid will cover one eye while trying to read. "That's a red flag," the eye doctor said.

Some children with one bad eye can show substantial improvement as early as their fourth birthday if they are treated. Treatment may include eye drops to blur the good eye and force use of the good one.

Neeley has worked in Calistoga for 16 years. She's a graduate of the optometry school at UC Berkeley.