Comparison of the Adaptive Optics Vision Analyzer and the KR-1 W for measuring ocular wave aberrations

The aim was to assess the agreement in the measurement of ocular aberrations between a new Adaptive Optics Vision Analyzer (AOVA, Voptica, Murcia, Spain) and a commercial aberrometer (KR-1 W, Topcon, Tokyo, Japan), both based on the Hartmann-Shack technique.

One experienced examiner measured 29 healthy right eyes nine consecutive times with the two instruments. The individual Zernike coefficients and the root mean square (RMS) of each order from the second to the fifth order, the higher-order RMS (RMS_HOA ), the total RMS (RMS_TOT ) and the values of the spherical equivalent (M) and Jackson cross-cylinder (J₀ and J₄₅ ) were compared. All aberrations were computed for a 4.0 mm pupil diameter.

Bland and Altman analysis showed good agreement between instruments and most of the parameters showed no statistically significant differences. Although the largest mean differences were obtained for the defocus coefficient C(2,0) and the spherical equivalent (M) with a mean difference (and standard deviation) of 0.190 ± 0.099 µm and -0.150 ± 0.188 D, respectively, they were clinically acceptable and significant correlations were found between the AOVA and KR-1 W for the major refractive components such as spherical equivalent (r = 0.995, p < 0.001), J₀ (r = 0.964, p < 0.001), J₄₅ (r = 0.901, p < 0.001) and C(4,0) (r = 0.575, p = 0.001).

The results suggest good agreement between instruments. Accommodation and misalignment of the measurements may play a role in some of the statistically significant differences that were obtained, specifically for defocus C(2,0), vertical coma C(3,-1) and spherical aberration C(4,0) coefficients; however, these differences were clinically irrelevant.