The evolution of the anterior chamber implant up to, and including, the Choyce Mark IX.

Since 1963, the Choyce Mark VIII lens, a quadrupedal, anterior chamber implant, has proved satisfactory following conventional intracapsular surgery in eyes of normal size, but less successful after primary extracapsular procedures and in small eyes. Reducing some of its dimensions by as much as 30% enables the surgeon to treat a much wider range of cataract problems through a smaller incision. The reduced-size version is known as the Choyce Mark IX anterior chamber implant. The quadrupedal principle has been preserved.