Evaluating data acquisition and smoothing functions of currently available videokeratoscopes.
OBJECTIVE
To compare the accuracy of computerized videokeratography systems using identical, calibrated test objects.


METHODS
Lions Eye Institute, Albany, New York.


METHODS
We evaluated the accuracy and smoothing of raw data acquisition (axial solution) of seven commercially available videokeratoscopes: Alcon EyeMap, Computed Anatomy TMS, EyeSys CAS, Humphrey MasterVue, Topcon CM-1000, Optikon Keratron, and TechnoMed C-Scan. We used six calibrated test objects to simulate clinical settings: spherical, spherocylindrical, simulated myopic ablation, hyperopic ablation, and a simulated central island.


RESULTS
None of the systems accurately imaged all objects. Although all systems imaged spherical objects with reasonable accuracy, errors greater than 4.0 diopters (D) frequently occurred in the central 6.0 mm optical zone (maximum error 10.0 D) Sources of error included excessive raw data smoothing, inability to read large transitions, loss of accuracy in the periphery, and poor central coverage.


CONCLUSIONS
The clinician should be aware of the potential limitations of corneal topography when making clinical decisions.
Belin
M W
MW
Albany Medical College, Department of Ophthalmology, Lions Eye Institute, New York 12208, USA.
Ratliff
C D
CD
D003315:Cornea / Q000033:anatomy & histology*; D003627:Data Interpretation, Statistical; D004867:Equipment Design; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000295:instrumentation*; D008953:Models, Anatomic; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity