Abstract
Purpose: :
To assess a new method of continuous curvilinear capsulorhexis (CCC) using a modified Intralase femtosecond (iFS) laser for a deeper focusing of the beam into the anterior chamber to locate the capsule bag surface and for performing capsulotomy in cadaver eyes ex vivo and in rabbit in vivo.
Methods: :
iFS-assisted capsulotomy (iFSCCC) was performed on 35 cadaver eyes (corneas intact or removed). Corneal thickness and anterior chamber depth (ACD) were measured using a PalmScan. Post treatment inspection was performed with a surgical microscope assessing ease of removal, circularity, and capsular bag integrity. Six New Zealand White rabbits underwent iFSCCC in the right eye and Manual CCC in the left eye. Preoperatively corneal thickness and anterior chamber depth were measured using a Pentacam HR Scheimpflug camera. Postoperative ease of capsulotomy tissue removal, circularity, and capsular bag integrity were evaluated. Following intraocular lens (IOL) implantation, eyes were followed for 1 month by slit-lamp biomicroscopy.
Results: :
Demonstration of a minimal 0.6 µJ laser energy to create the iFSCCC was in accordance with previously reported capsule cut threshold in the absence of cadaver corneas and can serve as a basis for future laser qualification prior to clinical evaluation. Pre-capsulotomy measurement of the ACD was preformed with the modified iFS laser guided range finding feature with a standard deviation of 0.541μm (cadaver eyes) and 0.23μm (rabbit eyes). In the rabbit model, iFSCCC diameter size accuracy was within 0.32mm of the planned target and centration of the capsular opening averaged 0.36mm from the center of the IOL. Manual CCC diameter size accuracy was within 0.74mm of planned target and centration of the capsular opening averaged 0.81mm from the center of the IOL. The Laser capsulotomy procedure time was 2 minutes longer than manual CCC (rabbit).
Conclusions: :
Modified iFS laser provides a new tool that may offer improved treatment capability, accuracy and precision over manual techniques during cataract surgery. Additional studies are warranted to evaluate safety and efficacy of the iFSCCC. These studies demonstrate that modified iFS laser can perform reproducible and accurate capsulotomy compared to manual techniques during cataract surgery.
Keywords: laser • cataract