Comparison of Internal and Total Optical Aberrations for 2 Aberrometers: iTrace and OPD Scan

PURPOSE: To compare and evaluate the total and internal aberrations measured by two aberrometers: the laser ray tracing aberrometer (iTrace, Tracey Technology) and the automatic retinoscope aberrometer (OPD Scan, Nidek). METHODS: A total of 54 healthy eyes were enrolled in the study. Following pupil dilation, aberrations were measured with the iTrace and OPD Scan. We compared the aberrations obtained from measurements obtained at pupillary diameters of 4 mm and 6 mm with the OPD Scan and iTrace. Aberrations of internal optics and total aberrations were compared for the two aberrometers. For each aberrometer and each eye, the averaged Zernike data were used to calculate various root-mean-square (RMS) data. These parameters, together with the refractive parameters, were then analyzed and complimented by paired t-tests. RESULTS: At a pupil diameter of 4 mm, the number of total aberrations in the entire eye showed significant differences for the mean values of spherical aberrations (Z4,0) obtained with the OPD Scan and iTrace aberrometers (p=0.001). Aberrations of the internal optics showed significant differences in the mean values of total RMS, coma (Z3,-1), and trefoil (Z3,3) between the iTrace and OPD Scan (p<0.001, p=0.01, p<0.001) for the same pupil diameter of 4 mm. At a pupil diameter of 6 mm, the two instruments showed a similar number of total aberrations. Aberrations of the internal optics showed significant differences in the mean values of total RMS, spherical aberration (Z4,0), and coma (Z3,-1) between the two devices (p<0.001, p=0.01, p<0.001). CONCLUSIONS: The iTrace and OPD Scan showed the largest number of differences for aberrations of internal optics rather than total aberrations for both pupil diameters. These results suggest that in healthy eyes, the two aberrometers may vary in some details. The aberrometers showed more agreement at a pupil diameter of 6 mm compared to 4 mm.

Ocular Aberrations and Contrast Sensitivity in Eyes Implanted with Aspheric and Spherical Intraocular Lenses

PURPOSE: To compare spherical aberration, higher-order aberration, and contrast sensitivity of eyes implanted with aspheric (AcrySof IQ) or spherical (AcrySof Natural) intraocular lenses. METHOD: Seventy-five eyes implanted with posterior chamber intraocular lenses were divided into two groups: AcrySof IQ (35 eyes) and AcrySof Natural (40 eyes). Wavefront analysis (spherical, higher-order and total aberration) using iTace, and contrast sensitivity (under photopic and mesopic condition) using Optec 6500 were performed at 1 month and 3 months postoperatively. RESULT: One month after surgery, the IQ IOL (intraocular lens) group had lower values of spherical aberration (p<0.001) and higher-order aberration (p=0.048) than the Natural IOL group. The IQ IOL group also showed better contrast sensitivities at 1.5- and 3-cpd spatial frequencies in mesopic conditions. Three months after surgery, the IQ IOL group had less spherical aberration (p<0.001) and higher-order aberration (p=0.027) than the Natural IOL group and showed better contrast sensitivities at the 3-cpd spatial frequency in mesopic conditions. CONCLUSIONS: Aspheric AcrySof IQ IOL induced significantly less higher-order aberration and spherical aberration than AcrySof Natural IOL. The contrast sensitivity was better under mesopic conditions in the AcrySof IQ IOL-implanted group.