Types

• Several different formats of movie projectors include 16 millimeter (mm), 35mm, 70mm and IMAX. Most 16mm film is used for industrial and corporate presentations, while 35mm and 70mm film is mostly for professional use and feature motion pictures, according to Media Technical Specialist Michael Nolte of Miracosta College.
  
  

How It Works

• Film is projected at a rate of 24 frames-per-second, but the human eye is tricked into seeing just one picture. A 3-D movie, however, creates an illusion of depth because slightly different 2-D images are projected onto the same screen. Special glasses let one eye perceive each image, but this can cause something researchers call "sensory conflict," essentially poisoning the body.
  
  

Effects

• Patricia Winkler, professor emeritus at Regis University, told MSNBC the symptoms of "sensory conflict" are nearly the same as getting carsick or seasick. This is because sensory conflict is a type of vestibular disorder (a dysfunction of one or more parts of the central nervous system that help process balance and spatial information). Common symptoms include dizziness, vertigo and disequilibrium.
  
  

Other Considerations

• Some film projectors trigger dizziness and other medical ailments, but unbeknown to some movie-goers, any visit to a theater could lead to seizures connected to photosensitive epilepsy. According to the Epilepsy Foundation, this occurs when individuals with sensitivity to flashing lights or contrasting visual patterns experience seizures triggered by visual stimulation.
  
  

Time Frame

• Children and adolescents are more likely to have an abnormal response to light stimulation, and the first light-induced seizure almost always occurs before age 20, according to Dr. Giuseppe Erba, a leading researcher for the Epilepsy Foundation. However, Dr. Lisa Haven reports in her studies to the Vestibular Disorders Association that about 35 to 40 percent of adults over the age of 40 have some sort of vestibular problems.
  
  

Prevention/Solution

• Dr. Erba says factors involved in light or photosensitivity include the frequency at which the light changes, the intensity of the light source, colors projected, the viewer's distance from the light source and even sleep deprivation. Solutions could mean something as simple as wearing optical filters (such as colored lenses), moving away from the screen to extend your field of vision and getting an appropriate amount of sleep before viewing any kind of projected image.
  
  

Future

• The film industry continues to move through a variety of technological innovations, including more expensive cameras, special projectors and larger screens. This does little to help those suffering from dizziness, vertigo and other more serious ailments, but does raise awareness when it comes to identification of the condition, says Dr. Erba. He also notes The Epilepsy Foundation has taken a leading role in fostering knowledge about the condition and disseminating information to the public and interested professionals.