Light microscopy and scanning electron microscopy analysis of rigid curved interface femtosecond laser-assisted and manual anterior capsulotomy.

PURPOSE: To study the microanatomic edge structures of anterior lens capsule specimens derived from manual and femtosecond laser-assisted capsulotomies.

SETTING: Department of Ophthalmology, Goethe-University, Frankfurt, Germany.

DESIGN: Experimental study.

METHODS: Of 60 eyes with lens removal and intraocular lens implantation, 30 received a manual capsulotomy and 30 received a femtosecond laser-assisted capsulotomy (Lensx, rigid curved interface, pulse energy 15 μJ, spot separation 4 μm, layer separation 3 μm). After anterior capsule removal, tissues were immediately fixed in 4.5% formalin. Approximately 30 minutes after fixation, the tissues were removed from the fixation containers and air dried for at least 2 hours. Fifteen capsules in each group had further staining for light microscopy (LM). The surface of the capsulotomy edge was the primary focus of LM and scanning electron microscopy (SEM). Cell configuration, capsule shape, and abnormalities were evaluated.

RESULTS: Subjective LM and SEM analysis showed smooth edges at all magnifications, no cell destruction, and cells up to the cutting edge in the manual capsulotomy group. Light microscopy demonstrated almost continuous anterior capsule incisions of the femtosecond laser-assisted capsulotomy, a prominent demarcation line along the cutting edge, and several tags and bridges. Scanning electron microscopy showed microgrooves and valley- and mountain-like structures as signs of the photodisruption process.

CONCLUSION: Compared with manual procedures, curved, rigid interface femtosecond laser-assisted capsulotomy specimens using 15 μJ pulse energy showed tags, bridges, rougher edges, and demarcation lines on the capsulotomy edges on SEM but subjectively estimated a more round shape on LM.

FINANCIAL DISCLOSURES: Mr. Klaproth received travel reimbursements and/or lecture fees from Alcon Laboratories, Inc., Rayner Intraocular Lenses Ltd., and Oculus GmbH. Dr. Kohnen received travel reimbursements, grant support, and/or lecture fees from Alcon Laboratories, Inc., Abbott Medical Optics, Inc., Bausch & Lomb, Carl Zeiss Meditec AG, Neoptics AG, Rayner Intraocular Lenses Ltd., and Schwind eye-tech-solutions GmbH and Co. KG; he is a consultant to Alcon Laboratories, Inc., Carl Zeiss Meditec AG, Rayner Intraocular Lenses Ltd., and Schwind eye-tech-solutions GmbH and Co. KG. No other author has a financial or proprietary interest in any material or method mentioned.