Comparison of two methods of marking the visual axis on the cornea during radial keratotomy

We compared two methods of marking the visual axis on the cornea during radial keratotomy surgery in 34 eyes of patients participating in the National Eye Institute Prospective Evaluation of Radial Keratotomy. The locations of the corneal light reflections produced by an optical centering device and by the operating microscope filament were identical in 18 eyes, overlapped partially or touched in ten eyes, and were separate in the remaining six eyes. The two corneal marks in this last group were close enough to make little practical difference. The two methods can be used interchangeably in clinical practice.