The American Board of Ophthalmology (ABO) is an independent, non-profit organization responsible for certifying ophthalmologists (eye physicians and surgeons) in the United States of America. Founded in 1916, the ABO was the first American Board established to certify medical specialists.

The ABO is the founding member of the American Board of Medical Specialties. Originally, a combined board of Ophthalmology & Otolaryngology, the specialties split into two board backed specialties in the 1960s.

Certification by the American Board of Ophthalmology is a voluntary process that involves a written and an oral examination. A candidate who passes both the written qualifying and oral examinations becomes a Board Certified Diplomate of the American Board of Ophthalmology and is entitled to use the letters D.A.B.O. after his or her name.

John Gibson Clarkson (July 1, 1861 – February 4, 1909) was a Major League Baseball right-handed pitcher. He played from 1882 to 1894. Born in Cambridge, Massachusetts, Clarkson played for the Worcester Ruby Legs (1882), Chicago White Stockings (1884–1887), Boston Beaneaters (1888–1892), and Cleveland Spiders (1892–1894).

He was elected to the Baseball Hall of Fame in 1963.

Clarkson compiled a career 328-178 record, placing him twelfth on the MLB list of all-time wins. Clarkson pitched over 600 innings in a season twice and won a career-high 53 games in 1885. In MLB history, only Charles Radbourn has won more games in a single season (59 in 1884). In just five seasons from 1885 to 1889, Clarkson won 209 games.

Clarkson had a wide variety of curve balls and was considered to be a calculating, scientific pitcher who carefully analyzed every hitter's weaknesses. Hall of Fame hitter Sam Thompson said of Clarkson: “I faced him in scores of games and I can truthfully say that never in all that time did I get a pitch that came where I expected it or in the way in which I guessed it was coming.”