CHARLOTTE, N.C. -- A small piece of metal in his eye, and not a sinus infection, caused Denny Hamlin to miss last week’s race at California.

Hamlin was not medically cleared to race last Sunday by doctors in the infield care center at Auto Club Speedway. He had visited the care center on Saturday and Sunday complaining of an irritation to his eye, and it was determined at the track that it was related to a recent sinus infection Hamlin had suffered.

Hamlin was referred to a local hospital for further evaluation, and once there, "a small piece of metal was found to be in Hamlin’s eye," Joe Gibbs Racing said in a statement Wednesday.

The metal was removed and JGR said "Hamlin felt immediate improvement." By then, the race at Fontana had already started and replacement driver Sam Hornish Jr. was behind the wheel of Hamlin’s No. 11 Toyota.

Hamlin underwent further testing in California before he was cleared to fly home to North Carolina. He was evaluated in Charlotte on Monday and again on Wednesday, when it was determined he had no lingering issues with his vision and is cleared to race this weekend at Martinsville Speedway.

Hamlin has four career victories at Martinsville and an average finish of eighth.

The timeline of Hamlin’s diagnosis and revelation it was a piece of metal in his eye and not a sinus infection comes a day after Dale Earnhardt Jr. called on NASCAR to release information regarding Hamlin not being cleared to race at California.