Abstract
Purpose: :
To study the influence of the fixed position of toric intraocular lens (IOL) on the corrective error of the total astigmatism.
Methods: :
This retrospective study comprised 19 eyes of 17 patients (mean age 64.1 years) who underwent phacoemulsification and a toric IOL (AcrySof IQ Toric IOL, Alcon, TX, USA) implantation. A toric IOL was fixated to the target axis around the corneal center determined before cataract surgery. The rotational error was defined as the difference between the target- and the achieved axes of the implanted toric IOL evaluated by the CCD-image of the anterior segment optical coherence tomography (CASIA, Tomey, Aichi, Japan) one month after surgery. The rotation error was evaluated based on the axis not only around the corneal but also around the IOL center (C-RE, IOL-RE, respectively). The difference of C-RE and IOL-RE was defined as the methodology-derived error (MDE). The distance between the corneal center and the toric IOL center was defined as IOL decentration. The correction error (CE) of astigmatism by toric IOL was calculated using the Alpin’s method. Correlations between C-RE , IOL-RE and CE were evaluated.
Results: :
The pre- and postoperative corneal astigmatisms were 2.53 ± 0.71 D, and 2.55 ± 0.67 D, respectively. The pre- and postoperative refractive astigmatisms were 2.60 ± 1.16 D, 0.95 ± 0.54 D, respectively. CE, C-RE, IOL-RE, MDE, and IOL decentration were 0.74 ± 0.45 D, 4.4 ± 3.0 °, 5.9± 4.8 °, 4.5± 3.4 °, and 0.30 ± 0.18 mm respectively. CE significantly correlated with IOL-RE (P=0.02), but not with C-RE (P>0.05). A significant correlation was found between MDE and IOL decentration (P=0.02).
Conclusions: :
The correction error of a toric IOL might be influenced not only by the rotational error of the IOL axis, but also by decentration of the IOL center for the corneal center.
Keywords: intraocular lens • astigmatism • clinical (human) or epidemiologic studies: outcomes/complications