Journal List > J Korean Ophthalmol Soc > v.50(12) > 1008440

Yum, Choi, Kim, and Lee: Comparison of Aberrations in Korean Normal Eyes Measured With Two Different Aberrometers



To compare ocular higher order aberrations measured by two different aberrometers in a sample of normal eyes.


We included 41 normal eyes of Koreans in this study. Ocular aberration data were obtained through three measurements per eye using Zywave and OPD-Scan devices. Spherical equivalent and higher order aberrations calculated in the central 6 mm zone and expressed as root mean square (RMS) values were analyzed.


A comparison of measurements between the Zywave and OPD-Scan devices demonstrated no statistically significant differences in the RMS values of total higher order aberration (p=0.11), but significant differences were detected in the RMS values of total spherical aberration, total coma and total trefoil (p<0.01).


The two different aberrometers that we tested are suitable for taking repeated measurements and are internally consistent, but not interchangeable.


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Figure 1.
Repeatability Coefficient (μm)* of OPD-Scan TM and Zywave TM. This graphs show the distribution of the differences between each total higher order aberration measurement and the mean of three consecutive measurements in each of the 41 eyes. (Repeatibility coefficient: OPD-ScanTM=0.11 μm and ZywaveTM=0.06 μm)* Repeatability Coefficient (μm)=95% confidence interval for repeated measurements; HOA=higher order aberration.
Figure 2.
Correlations of OPD-ScanTM and Zywave TM. HOA=higher order aberration; SA=spherical aberration; r=Pearson correlation coefficient (p<0.01).
Table 1.
Comparisons of spherical equivalent of manifest refraction, OPD-Scan TM and Zywave TM
  MR* OPD scan TM Zywave TM OPD scan TM-MR*(pair t-test) Zywave TM-MR*(pair t-test) OPDscan TM-Zywave TM (pair t-test)
Spherical equivalent (Diopters) −0.26±0.75 −0.21±0.85 +0.11±0.83 0.05±0.36(p=0.11) 0.37±0.33(p<0.01) −0.31±0.15(p<0.01)

* MR=manifest refraction.

Table 2.
Repeatability Coefficient (μm)* of OPD-Scan TM and Zywave TM
  OPD scan TM ZywaveTM
Total higher order aberration (μm) 0.11 0.06
Total Spherical aberration (μm) 0.12 0.05
Total Coma (μm) 0.13 0.06
Total Trefoil (μm) 0.13 0.08

* Repeatability Coefficient (μm)=95% confidence interval for repeated measurements.

Table 3.
Comparisons of higher order aberrations between OPD-Scan TM and Zywave TM
  OPD scan TM Zywave TM OPD scan TM-Zywave TM (paired t-test)
Total higher order aberration (μm) 0.436±0.143 0.409±0.144 0.027±0.097
Total Spherical aberration (μm) 0.133±0.126 0.168±0.128 −0.335±0.097
Total Coma (μm) 0.199±0.123 0.233±0.129 −0.034±0.113
Total Trefoil (μm) 0.306±0.131 0.217±0.096 0.089±0.120

Root mean square value (μm) of aberration from 3 rd to 5 th order in the central 6-mm area was calculated.

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