TORONTO (AP) The CFL is adding a two-minute test to standard sideline examinations for suspected concussion. The aim is to quickly determine if a player should be pulled from the field or can safely return to play.

The King-Devick test was initially developed by American optometrists Alan King and Steven Devick in 1976 to diagnose eye movement dysfunction that affects reading ability. A player rapidly reads aloud lines of irregularly spaced, nonsequential numbers on flip cards or smartphone/tablet apps.

In the last five years, research groups began studying the test to see if it could detect concussion, a brain injury that can affect attention and concentration.

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The CFL is trying out the test for players on four teams - the B.C. Lions, Edmonton Eskimos, Calgary Stampeders and Winnipeg Blue Bombers. The NFL is helping fund the CFL project, and this testing is not in place in the NFL yet.

''It's really just to collect some numbers to see if this gives us an additional tool,'' said Kevin McDonald, CFL vice president of football operations. ''We thought there was a real opportunity to get some meaningful data.''

The CFL is facing a $200 million lawsuit filed in May by two former players, who are seeking class-action status on behalf of all retired players going back to 1952. The suit alleges the league, former commissioner Mark Cohon, a Toronto doctor and clinic withheld information about how repeated concussions can lead to long-term cognitive disorders.

In April, a U.S. judge approved a settlement involving the NFL, which had long been accused of hiding the cumulative effects of concussions. The agreement involves thousands of concussion lawsuits.

McDonald denied that the CFL is adopting the test in response to the lawsuit.

''This is about the health and safety of our players,'' he said.

Dr. David Dodick, a neurologist at the Mayo Clinic in Phoenix who specializes in concussions, said numerous studies have concluded the King-Devick test is highly accurate in picking up the brain injury.

''And that's what makes it a very valuable tool,'' said Dodick, noting that the time-based test is more objective than standard balance and cognition assessment tests and is not affected by player fatigue.

Players are given K-D tests before the start of their season to establish a baseline time for recounting all 120 numbers, which are laid out in increasingly difficult-to-follow patterns.

If a player is suspected of having sustained a concussion during play, the athlete is retested and the results compared. Should the task take longer to complete or include errors, the player should be removed from play and seen by a doctor.

The Mayo Clinic this year endorsed the test for school-based, amateur and pro contact sports in a licensing agreement with King-Devick Test Inc.

''We recognized the need for a simple, rapid and cost-effective sideline test,'' Dodick said. ''So to have an objective and reliable test, we felt it was very important and we saw the potential for this King-Devick test to make a huge difference in increasing the likelihood of identifying concussion on the sidelines.''

Dr. Paul Echlin, a Burlington, Ontario, sports medicine physician, treats young athletes with head trauma. He doesn't use the K-D examination and questions the ability of a two-minute test to diagnose the complex condition with certainty - especially when administered by parents or coaches.

''One test can't say someone is concussed or nonconcussed,'' said Echlin, adding that if there's suspicion a player might have a brain injury, the player should be removed from play and fully evaluated by a physician.

Dodick at the Mayo acknowledged that some of his colleagues have voiced a similar criticism, saying the test should be given to youth athletes by qualified professionals - not parents or coaches.

''By the same token, do we not do anything? When we do have the tool, do we not administer it?'' he said. ''What would the harm be? You identify someone slower and you take them out. You err on the side of caution.''