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Session Title: Intraoperative Biometry and Correction of Astigmatism
Session Date/Time: Monday 07/10/2013 | 08:00-10:00
Paper Time: 08:00
Venue: Main Lecture Hall (Ground Floor)
First Author: : O.Findl AUSTRIA
Co Author(s): : N. Hirnschall M. Weber S. Maedel P. Draschl J. Wiesinger
One of the major advantages of femtosecond-laser assisted cataract surgery is the precise capsulotomy which supposedly results in better IOL positioning. Aim of this study is to evaluate the influence of rhexis size and shape on tilt, decentration and post-operative anterior chamber depth.
VIROS - Vienna Institute for Research in Ocular Surgery, Department of Ophthalmology, Hanusch Hospital, Vienna, Austria
In this continuous cohort study, consecutive patients who were scheduled for cataract surgery performed by 9 surgeons of different experience, ranging from experienced consultants to trainees, were included. Three different IOL models were used in this series, all modern acrylic IOLs. One hour after standard phaco-surgery, retroillumination photographs were taken and partial coherence interferometry measurements of the anterior chamber depth (ACD, AC-Master, Carl Zeiss Meditec AG, Germany) were performed. The rhexis openings were classified into ideal sizing and positioning (i.e. 4.5 to 5.5 mm with complete overlap) and too large, too small or eccentric. Three months after surgery, these measurements were repeated and additionally, tilt and decentration were measured using a Purkinje meter. For analysis the rhexis shape factor (RSF) was assessed (rhexis mode of the AQUA software), which is the standard deviation of 50 consecutive distances (7.2° apart) of the IOL rim to the rhexis edge for each retroillumination image.
In total 300 eyes of 300 patients were included. Preliminary results of the first 100 eyes showed a mean tilt and decentration of 3.8° (SD: 2.1) and 0.4 mm (SD: 0.2), respectively. Mean rhexis diameter 1 hour and 3 months post-operatively was 4.76 mm (SD: 0.5) and 4.89 mm (SD: 0.48), respectively. Mean RSF 1 hour and 3 months post-operatively was 0.27 mm (SD: 0.13) and 0.24 (SD: 0.10), respectively. This change was found to be significant (p=0.046). Correlation between RSF and tilt as well as decentration was weak (r2= 0.02 and r2= 0.04, respectively). Even in those cases, where no rhexis overlap with the IOL was observed (18 cases), tilt and decentration were not significantly different (p=0.564 and p=0.293) compared to normal cases.
Modern IOL designs showed good post-operative capsular bag positioning that appears to be relatively independent of the shape and size of the capsulorhexis opening.
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