Comparison of the VISX wavescan and OPD-scan III with the subjective refraction

To compare the refractive errors measured by the VISX WaveScan, OPD-Scan III and the subjective refraction. The optometry accuracy of computer operated aberrometer used before refractive surgery has been debatable. Hence, a clear study on the role of such automated equipment in optometry is the need of the hour as compared to subjective refraction.

Seventy-six patients (152 eyes) were recruited from January 2013 to December 2013. All patients were measured with subjective refraction by the phoropter (NIDEK, RT-5100), objective refraction by the WaveScan (AMO Company, USA), OPD-Scan III (Nidek Technologies, Japan). The sphere, cylinder, axis of the three methods were compared and analyzed.

The diopter of sphere power measured by WaveScan was lower than that of the subjective refraction and the difference was 0.13 ± 0. 30D (t = 3. 753, p <0. 001). While the diopter of cylinder power was higher and the difference was 0.13 ±0.43D (t = 3. 664, p <0. 001). There was no significance for sphere, cylinder and spherical equivalent between OPD-Scan III and subjective refraction (p >0. 05). The value of the difference between WaveScan and subjective refraction was 5.87°±6.19°on average, while the difference between OPD-Scan III and subjective refraction was 3.82°±3.95°on average. The differences between the two were statistically significant (t =2. 817, p =0. 006).

The results of sphere and cylinder measured by WaveScan and subjective refraction were different. As the latest integrated equipment, the Nidek OPD-Scan III gives a more accurate measurement of objective refraction when compared with subjective refraction. The latest Nidek OPD-Scan III may prove to be an useful tool for preoperative optometry deviation based on objective refraction.