Lenspower Calculation and Centration of an Ashperic IOL
Becker K. A., Holzer M. P., Reuland A., Auffarth G. U.
Heidelberg Research Group Intraocular Lenses and Refractive Surgery, Department of Ophthalmology, University of Heidelberg
Purpose: Aspheric IOL´s are supposed to optimize optical characteristics of intraocular lenses (IOL). Therefore, it is essential to achieve an exact postoperative refraction and a central position of the IOL in the capsular bag.
Method: In 43 patients (mean age 70.9 ± 8.3 years) the Pharmacia Z9000 IOL was implanted after uneventful phacoemulsification in topical anesthesia. IOL calculation was performed with Holladay-, Haigis-, and SRKII-formula. 6 months after cataract surgery spherical equivalent and IOL centration was analysed. Measurement of centration was done by using slitlamp photographs which were evaluated by an image analysis program.
Results: Preoperative VA was 0.4 ± 0.2 and increased to 0.8 ± 0.1 (spherical equivalent 0.3 ± 0.6 D) 6 months after surgery. The difference between the preoperative calculated target refraction for a certain lenspower and the spherical equivalent evaluated postoperatively was determined: 0.6 ± 0.1 D for Holladay-,0.2 ± 0.1 D for Haigis- and 0.9 ± 0.1 D for SRKII-formula. Mean IOL decentration from the optical axis was 0.4 ± 0.1 mm.
Conclusions: The aspheric IOL Z9000 showed very good postoperative functional results. A correct lens power calculation and a good central position of the IOL in the capsular bag are essential to optimize surgical outcomes. In this study the Haigis-form
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