Initial selection of soft contact lenses based on corneal characteristics.
OBJECTIVE
To determine apical radius, surface asphericity, and horizontal visible iris diameters (HVID) in normal subjects and to find out which has the greatest influence on the corneal sagittal depth.


METHODS
Videokeratoscopic data were analyzed to determine the apical radius and the p-value of the near horizontal principal meridian for 73 right and 77 left eyes. The HVID also were measured.


RESULTS
Scatterplots of sagittal depth versus apical radius, p-value, and HVID indicated the strongest association between the sagittal depth and the HVID.


CONCLUSIONS
Normal variations in corneal asphericity have the least influence whereas normal variations in HVID have the greatest influence in changing the corneal sagittal depth. The most appropriate measurement to take to select the optimum soft contact lens specification may be the HVID.
Douthwaite
William A
WA
Department of Optometry, University of Bradford, West Yorks, UK. w.a.douthwaite@bradford.ac.uk
D000328:Adult; D003263:Contact Lenses, Hydrophilic; D003315:Cornea / Q000473:pathology; D019781:Corneal Topography; D006801:Humans; D007498:Iris / Q000473:pathology; D008875:Middle Aged; D008953:Models, Anatomic; D017755:Prosthesis Fitting