Race officials say Corvallis, Ore., neurosurgeon Cliff Roberson scratched Wednesday morning at the Rohn checkpoint after suffering minor eye injuries.

Roberson ran the race several times in the early 1990s. His entry this year was a 60th birthday gift from his wife. A record field of 92 mushers remain in the running, including two other Oregonians, Rachael Scdoris of Bend and Liz Parrish of Klamath Falls.

John Kirby for kgw.com

A team of dogs prepares to take off at the starting line.

This year, 96 mushers with a team of between 12 and 16 dogs each, began the 1049-mile course in a ceremonial start in downtown Anchorage. After a short run in the city, the racers packed up and moved to Willow, Alaska, 75 miles north of Anchorage, for the official “restart” of the race.

The official race includes a trek through two mountain ranges, forests, tundras , frigid temperatures and occasional bouts of zero visibility. The finish line is in Nome on the Bering Sea, near the western edge of the continent.

 Slideshow: Race photos

Rachael Scdoris, a 22-year-old graduate of Redmond High School, finished her first Iditarod in 2006. Born with Congenital Achromatopsia, a rare vision disorder, she is light-sensitive, color-blind and limited to 20/200 vision. A member of the National Association of Blind Athletes, Scdoris was also one of the torch carriers for the Salt Lake City Olympic Games in 2002.

“The only real challenge that I haven’t been able to figure out by myself is that I can’t see trail markers, so I need someone else to tell me which way to go,” said Scdoris, who joins another sled team on the trail which acts as a guide. This is her third Iditarod.

Liz Parrish is an innkeeper and owner of Briar’s Patch Sled Dogs near Klamath Falls and is running her first Iditarod. Why do a race like this? “It’s my 50th birthday this year, and I wanted to do it. I’ve been preparing for a decade for this,” said Parrish.

A 43-year-old attorney from Washington State, Steven Madsen, also is representing the Pacific Northwest. A graduate of Seattle University and musher since 1991, Madsen has completed two Iditarods and raises 24 huskies at his home in Cougar. Why do the race? “It’s just about personal achievement. I like being out on the trail with the dogs,” said Madsen. What were the biggest challenges in past years on the Iditarod trail? “The course is pretty tough. I broke a sled one year, and broke some ribs another year, but I just kept going,” said Madsen. “The biggest fear is Moose. They can be pretty dangerous.”

14-day trek in harsh conditions

The race starts each year in Anchorage on the first Saturday of March. But sometimes ideal, sometimes brutal conditions cause the race to last from 8 to 17 days. Even then, the end can be a photo finish. In 1978, Dick Mackey edged-out fellow Alaskan, and five-time Iditarod winner Rick Swenson by only one second at the finish line after a long 14-day trek.

The Iditarod Trail, a National Historic Trail, began as a supply route from the coastal towns of Seward and Knik to areas of the central interior and to central west coastal towns including Nome. Mail and essentials came in, and gold came out. In 1925, when diphtheria threatened Nome, the trail supplied the much- needed serum to limit the outbreak. The current Iditarod race series started in 1973 with a field of 34 teams.

If you'd like to track the competitors, a Web site created for the Iditarod race contains all the latest information on the progress of each racing team.