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J. N. Crosson, C. D. Reilly, R. A. Lyons, V. A. Panday; Toric IOLs vs. LRIs: A Pentacam Zernike Analysis and Wavefront Analysis of Astigmatism Correction at the Time of Cataract Surgery. Invest. Ophthalmol. Vis. Sci. 2008;49(13):1034. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To examine the effectiveness of toric IOL insertion versus LRIs for correction of astigmatism during cataract surgery using Pentacam zernike analysis and wavefront analysis.
A total of ten eyes were identified by chart review, five in which toric IOLs had been placed, and five in which LRIs had been performed to correct astigmatism during cataract surgery. Pre-operative visual acuity and manifest refraction were noted. Each patient underwent measurement of post-operative visual acuity, post-operative manifest refraction, scheimpflug images with the Pentacam, and wavescans. Pentacam images of the toric IOL eyes were then compared to images of the LRI eyes in terms of regularity of astigmatism, degree of astigmatism, Q value, and zernike analysis for higher order aberrations (HOAs). Wavescans of each patient group were also compared in terms of RMS error, HOAs, and HOA%.
The mean post-operative cylinder remained unchanged in the LRI group but decreased from 2.7 D preoperatively to 0.55 D in the toric IOL group. The mean post-op Q-value was -0.08 in the toric IOL group and 0.004 in the LRI group. All 5 LRI eyes had mildly irregular astigmatism post-operatively, while the toric group had 3 eyes with regular astigmatism, 1 eye with mildly irregular astigmatism, and 1 eye with very irregular astigmatism. Pentacam zernike analysis revealed greater total coma in the LRI patient group, but more trefoil and spherical aberration in the toric IOL patient group. Wavefront analysis revealed an increase in coma, trefoil, spherical aberration, RMS error of HOA, and HOA% in the toric group. Total RMS error was higher in the LRI group.
It appears that toric IOLs maintained a more negative Q value and attained more predictable reduction in post-operative refractive cylinder and less irregular astigmatism compared to limbal relaxing incisions. Pentacam zernike analysis and wavefront analysis are difficult to interpret because preoperative Pentacams and wavescans were not performed on these patients; however, there were greater HOAs in the toric IOL group. The Toric IOL group appeared to have greater HOA percentage compared to the LRI group because they performed better than LRIs in this small sample size in reducing overall total aberrations. Increased HOA in the toric group may be due to preoperative factors that were not measured. These trends call for further studies incorporating larger sample sizes to examine higher order aberrations in toric IOL and LRI patients.
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