Anterior Capsule Tears After Laser-Aided Cataract Surgery

Laurie Barclay, MD

October 03, 2013

Femtosecond laser-assisted cataract surgery (FLACS) may cause postage-stamp perforations and additional aberrant pulses, leading to an increased rate of anterior capsule tears, according to a prospective, multicenter, comparative cohort case series published online September 30 in Ophthalmology.

"Capsular complications after [FLACS] were increased in an early study, which is thought to be the result of the initial learning curve," write Robin G. Abell, MBBS, from the Tasmanian Eye Institute in Launceston, Tasmania, Australia, and colleagues. "However, complications were significantly less in the subsequent series at the same facility (both studies performed with an earlier docking system of the commercial laser platform). Studies also have shown improved overlap, centration, size, and circularity of anterior capsulotomy with FLACS."

The goals of the current study were to determine the incidence of anterior capsular tears after FLACS compared with after phacoemulsification cataract surgery (PCS) and to use scanning electron microscopy (SEM) to evaluate the ultrastructural features of anterior capsulotomy specimens from both procedures.

"The authors should be congratulated for publishing an honest, large-scale, and real-life study on laser anterior capsulotomies (LAC) involving multiple surgeons," Harvey S. Uy, MD, clinical associate professor of ophthalmology at the University of the Philippines–Philippine General Hospital, Manila, told Medscape Medical News. "Another strength is the structural analysis of the capsule buttons, which illustrated differences between manual capsulorrhexes, using different machines and LAC capsules."

The researchers compared the anterior capsule tear incidence in a prospective cohort of all 1626 consecutive patients who underwent FLACS or PCS by 2 surgeons from centers A and B. Four surgeons from centers A, B, C, and D collected anterior lens capsules, using 3 different commercially available femtosecond platforms, each with latest version upgrades. They prepared lens capsule tissue for SEM from 10 samples for patients undergoing PCS and from 40 samples for patients undergoing FLACS.

Compared with the PCS group, the FLACS group had a significantly increased rate of anterior capsule tears (FLACS 15/804 [1.87%] vs PCS 1/822 [0.12%]; P = .0002). The anterior capsule tear extended to the posterior capsule in 7 cases. All cases occurred in patients who had complete capsulotomy.

SEM revealed capsule margin irregularity and multiple, apparently misplaced laser pits in normal tissue, approximately 2 to 4 mm apart, and at a range of 10 to 100 mm radially from the capsule edge.

"[LAC] integrity seems to be compromised by postage-stamp perforations and additional aberrant pulses, possibly because of fixational eye movements," the study authors write. "This can lead to an increased rate of anterior capsule tears, and extra care should be taken during surgery after femtosecond laser pretreatment has been performed."

Study Limitations and Clinical Implications

Dr. Uy, who has performed trials for Lensar in the last year at Pacific Eye and Laser Institute, Makati, and St. Luke's Medical Center in Quezon City, the Philippines, notes that a major study limitation is the lack of randomization. This could cause selection bias, with more difficult cases possibly being assigned to LAC.

"Because the technology is new, the surgeons may still be at a learning curve in terms of adjusting the machine settings and surgical technique," Dr. Uy said. "From my own surgical experience, it took a while for man and machine to get to 100% free-floating capsulorrhexis."

He noted a "major flaw " in the study is the lack of clinical data from centers C and D, using Lensx and Lensar machines, which were different from the Catalys machines used at clinical centers A and B.

"The femtocataract procedure is a highly technically complex one involving different laser pulse widths, energy levels, imaging method, and software control," Dr. Uy pointed out. "It would be erroneous to project that similar clinical outcomes would be obtained using different machines even if there are histological similarities."

To resolve these issues, Dr. Uy recommended a randomized clinical trial involving experienced surgeons using different machines.

"Clearly, there are structural differences between LAC and [manual capsulorrhexis] capsules, [but] the link between these changes and capsular strength has not been fully established in human eyes," Dr. Uy said. "We have successfully used hooks to stabilize LAC-cut capsular bags with inherently weak zonules and have found the LAC capsule edges had sufficient strength to support the hooks."

"However, it would be prudent for a starting surgeon to select easy cases while getting the feel for femtosecond cataract surgery," Dr. Uy concluded. "Just like with a new phaco machine, once adjustments in machine settings, patient positioning, software, and energy selection are made, the results improve and the procedure becomes safer."

The authors have disclosed no relevant financial relationships. Dr. Uy has performed trials for Lensar.

Ophthalmology. Published online September 30, 2013. Abstract


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