Abstract
Purpose
To assess the changes of corneal aberration in the front and rear surface measured by Pentacam® following cataract surgery.
Methods
Thirty-two eyes of 30 consecutive patients that underwent phacoemulsification and IOL insertion via 3 mm superotemporal corneoscleral incision were examined. The corneal aberration was measured with Pentacam® (Oculus, Wetzlar, Germany) at 1 week and 1 month after the surgery, and these postoperative values were compared with values taken before the operation. The data were analyzed from 6 mm pupil size, using Zernike's polynomial expansion.
Results
In anterior corneal aberration, Z (4, −2); secondary astigmatism at 1 week postoperatively and Z (3, −3); the trefoil at 1 month postoperatively changed significantly (p <0.05). By contrast, in posterior corneal aberration, Z (2, −2), Z (2, 0), Z (2, 2), Z (3, 1), Z (4, −4), and Z (4, −2) changed significantly (p <0.05). However, there were no significant changes at 1 month postoperatively (Paired t-test).
Conclusions
There were significant changes in posterior corneal aberration compared to anterior corneal aberration at 1 week postoperatively. However, the corneal aberration recovered to the preoperative level at one month after the operation. Presumably, these results might be due to the corneal edema of the incision site, caused by measuring the corneal thickness in the early phase of surgery.
References
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Table 1.
Postoperative changes of corneal aberration on the front side. This is the measurement of aberration based on average Zernike coefficient of the front cornea at the time of postoperative one week, one month and before surgery. (optic zone 6 mm)
Preoop |
Postop 1 week |
Postop 1 month |
||||
---|---|---|---|---|---|---|
Zernike Coefficients (Mean) | Aberration | Zernike Coefficients (Mean) | Aberration | Zernike Coefficients (Mean) | Aberration | |
Z(2,2) Astigmatism | −0.161 | −0.061 | −0.084 | −0.032 | 0.099 | 0.037 |
Z(2,0) Defocus | 59.339 | 22.311 | 57.334 | 21.558 | 59.399 | 22.334 |
Z(2,-2) Astigmatism | 0.17 | 0.064 | 0.529 | 0.199 | 0.095 | 0.036 |
Z(3,-3) Trefoil | 0.054 | 0.020 | 0.017 | 0.006 | −0.008* | −0.003* |
Z(3,-1) Coma | −0.088 | −0.033 | −0.040 | −0.015 | −0.052 | −0.020 |
Z(3, 1) Coma | −0.027 | −0.010 | −0.114 | −0.043 | −0.049 | −0.018 |
Z(3, 3) Trefoil | −0.011 | −0.004 | −0.027 | −0.010 | 0.004 | 0.002 |
Z(4,-4) Tetrafoil | −0.086 | −0.032 | 0.025 | 0.009 | −0.076 | −0.029 |
Z(4,-2) Secondary astigmatism | 0.092 | 0.035 | 0.020† | 0.008† | 0.009 | 0.003 |
Z(4, 0) Spherical aberration | 0.678 | 0.255 | 0.678 | 0.255 | 0.737 | 0.277 |
Z(4, 2) Secondary astigmatism | −0.014 | −0.005 | −0.062 | −0.023 | −0.012 | −0.005 |
Z(4, 4) Tetrafoil | −0.054 | −0.020 | −0.009 | −0.003 | 0.024 | 0.009 |
Table 2.
Postoperative changes of corneal aberration on the rear side. This is the measurement of aberration based on average Zernike coefficient of the rear cornea at the time of Postoperative one week, one month and before surgery. (optic zone 6 mm)
Preop |
Postop 1 week |
Postop 1 month |
||||
---|---|---|---|---|---|---|
Zernike Coefficients (Mean) | Aberration | Zernike Coefficients | Aberration | Zernike Coefficients (Mean) | Aberration | |
Z(2, 2) Astigmatism | −0.184 | 0.007 | −0.092* | 0.004* | −0.052 | 0.002 |
Z(2, 0) Defocus | 71.485 | −2.859 | 69.389† | −2.776† | 67.648 | −2.706 |
Z(2, −2) Astigmatism | 1.51 | −0.060 | 1.561‡ | −0.062‡ | 1.523 | −0.061 |
Z(3, −3) Trefoil | 0.044 | −0.002 | 0.074 | −0.003 | 0.089 | −0.004 |
Z(3, −1) Coma | −0.178 | 0.007 | −0.089 | 0.004 | −0.096 | 0.004 |
Z(3, 1) Coma | −0.649 | 0.026 | −0.633§ | 0.025§ | −0.554 | 0.022 |
Z(3, 3) Trefoil | 0.525 | −0.021 | 0.557 | −0.022 | 0.548 | −0.022 |
Z(4, −4) Tetrafoil | 0.085 | −0.003 | 0.147∏ | −0.006∏ | 0.148 | −0.006 |
Z(4, −2) Secondary astigmatism | 0.021 | −0.001 | 0.036 | −0.001 | 0.028 | −0.001 |
Z(4, 0) Spherical aberration | 0.604 | −0.024 | 0.607 | −0.024 | 0.591 | −0.024 |
Z(4, 2) Secondary astigmatism | −0.321 | 0.013 | −0.302# | 0.012# | −0.255 | 0.010 |
Z(4, 4) Tetrafoil | −0.530 | 0.021 | −0.542 | 0.022 | 0.553 | −0.022 |
Table 3.
Changes of corneal thickness measured by pachymeter mode of Pentacam® at 12, 3, 6, 9 o'clock position & center (optic zone 6 mm). Corneal thickness increased statistically significant at 12 o'clock near incisional site at postoperative one week compared with before surgery. However, changes were recovered at one month after surgery (* p=0.00002).