Contact lens back surface specification derived from the EyeSys videokeratoscope

Rigid corneal lenses were designed for 36 subjects using the software available with the EyeSys Corneal Analysis System 2000 (software version 2.00W) and a program from the textbook 'Contact lens Optics and Lens Design' Both alignment and apical clearance designs were investigated. It was found that the EyeSys lenses produced tear layer thickness and axial edge clearance values that were excessive in some cases, especially for flatter corneas. In the case of an alignment mode of fitting, the designs were relatively steep in the back optic zone and flat in the periphery when compared with designs derived from the textbook.