A CLINICAL-TRIAL OF THE SUN SK-2000 COMPUTER-ASSISTED VIDEOKERATOSCOPE

A clinical trial was performed on 20 optometry students in order to ev aluate the suitability of the SUN SK-2000 (SUN contact lens company, J apan) computer-assisted videokeratoscope for use in clinical practice. Suitability was assessed by observing three factors: the accuracy, re peatability and agreement for central mean corneal power (MCP) with a keratometer (Javal Schiotz). Measurements of eight peripheral points a nd the central radius of curvature were made on 20 optometry students and on an 8 mm calibration surface using the SUN SK-2000. The SUN SK-2 000 accurately determined the 8 mm calibration surface (supplied by ma nufacturers) to be spherical (SD = +/-0.013, P = 0.776). Careful align ment was found to be an important factor in determining the actual rad ius of the calibration sphere. Unfortunately, the system required meas urements to be taken at a point which was not coincident with the line of sight. A simple improvement to this has been suggested. Readings w ere most repeatable for central corneal radii. Peripheral radii showed the most repeatability for the horizontal and inferior corneal radii. It has been suggested that the ocular adnexa may be a possible cause for the poor repeatability in the superior area of the cornea. The lev el of agreement between the Javal Schiotz keratometer and the SUN SK-2 000 in terms of mean refractive error (MRE) was not found to be suffic ient for the two instruments to be interchangeable (P = 0.011). The C- 0 and C-45 components of corneal astigmatism were found to have little association with the keratometer.