Eye patient Lyly Ung hasn't seen the new "Pirates of the Caribbean" movie, but she has something in common with its star, Johnny Depp. Neither one of them will be able to enjoy the film in 3-D.
"I have a condition called convergence insufficiency, the inability of the eyes to converge together, especially at near," said Ung.
That inability to focus both eyes on a single point, also known as a binocular disorder, can make it difficult for patients to watch a 3-D effect, or see it at all. While doing publicity for the new "Pirates of the Caribbean" film, Depp told interviewers he's completely unable to see in 3-D. Although he didn't offer details on his condition, doctors say cases are common.
"Approximately one-in-five people going in to watch 3-D movie will experience no 3-D or have visual symptom related to a binocular vision disorder," said Elio Polsinelli, O.D., from the California Optometric Association.
Polsinelli says the disorder most often results from a lack of coordination in the muscles that control the eyes. It can also affect reading and general depth perception, but can be treated in several ways including with corrective lenses.
"The first treatment would be is to get the proper prescription, you want to make sure both eye has proper focus in order to receive the double images that's being projected onto the screen," said Polsinelli.
He says vision therapy can also help strengthen and retrain the eyes to focus in tandem. When these images shift back and forth, it forces a patient's eyes to engage and then relax. Ung says the retraining helped her focus much more easily when she reads, and although she can now see 3-D, still finds it uncomfortable to watch.
"If you asked me to tell you sequentially what happened, I probably couldn't tell because I usually sleep half the time I was there," said Ung.
By the way, symptoms for binocular disorder include nausea, headaches, and difficultly keeping focused on a page while reading.
Written and produced by Tim Didion