[3] In his first professional tournament, the 1984 International Open, he won four qualifying matches, 5–2 against Maurice Parkin, 5–1 against Eddie McLaughlin, 5–4 against Jack Fitzmaurice and 5–4 against Mike Hallett, before losing 3–5 to Willie Thorne.

[4] He reached the final stages (last 32 or better) of the World Snooker Championship six times, but never in consecutive years.

[1] He was the runner-up in the 1989 Hong Kong Open, losing 8–9 to Mike Hallett after leading 8–6.

[5] O'Kane first reached the top 32 in the world rankings for the 1985/1986 season, returning three years later.

[6] O'Kane died after suffering a brain bleed-causing fall at his place of residence on 14 May 2024.