Institutional members access full text with Ovid®

Neophyte Skill Judging Corneoscleral Lens Clearance

Fuller, Daniel G.; Chan, Nancy; Smith, Brenton

doi: 10.1097/OPX.0000000000000800
Original Articles

Purpose: This study examines the accuracy of neophyte clinicians’ assessments of central corneal clearance (CCC) of a corneoscleral lens using lens center thickness (CT) as a biometric scale.

Methods: A normal participant was fit with a corneoscleral lens on both eyes. Observers (n = 34) from the final semester of their fourth year in optometric clinical training were instructed to estimate the amount of CCC through the approximate geometrical center of the lens using a standardized script which included a photograph identifying various zones. Observer estimates were then compared against anterior segment-OCT (AS-OCT) values obtained during calibration.

Results: Mean observer estimates of central corneal clearances were OD 220.5 ± 121.microns (range 50 to 480 microns) and OS 398.0 ± 159.1 microns (range 140 to 800 microns). The mean AS-OCT values were OD 105.5 ± 11.microns (range 84 to 121 microns) and OS 340.8 ± 15.2 microns (range 315 to 362 microns). Mann-Whitney test was statistically significant for comparison of median values OD (177.0; p = 0.001) and OS (260.0; p = 0.012).

Conclusions: Neophyte clinicians in the final semester of their fourth year of optometric clinical training tend to significantly overestimate the amount of CCC in a normal subject with declining accuracy as the amount of clearance diminishes.




The Eye Center, Southern College of Optometry, Memphis, Tennessee (DGF, BS); and the Lasik Vision Institute, San Bruno, California (NC).

Daniel G. Fuller, The Eye Center, Southern College of Optometry, 1225 Madison Avenue, Memphis, TN 38104. e-mail:

Supplemental digital content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal’s Web site (

© 2016 American Academy of Optometry