SINCE the advent of Jackson's cross cylinder in 1887, many modifications have been suggested and used. Among these have been a rotating cross cylinder for use in a trial frame, by Hornbogen1; a cross cylinder with additional markings for
EGAN JA. A MODIFIED CROSS CYLINDER. AMA Arch Ophthalmol. 1951;46(2):153–154. doi:10.1001/archopht.1951.01700020159005
Ophthalmology in JAMA: Read the Latest
Customize your JAMA Network experience by selecting one or more topics from the list below.