Femtosecond laser use shows very low rate of capsule tears

As early as 2009, people were beginning to realize the demand for perfect outcomes after cataract surgery was growing concomitantly with the popularity of premium IOLs, and that femtosecond laser technology may be a novel means to create circular capsulorhexis with even greater precision than manual techniques.

By 2014, the literature was starting to show the femtosecond laser can create more stable refractive results, with more precision and better capsulotomy sizing than manual procedures. Two clinical issues observed early during the learning curve were capsular block syndrome and anterior capsule tears.

A large, long-term study presented during the 2016 meeting of the American Society of Cataract and Refractive Surgery has found no further case of capsular block and a very low rate of anterior capsule tears, indicating that the significant advances in laser technology, patient interfaces and surgical technique have now resolved these issues.

Tim Roberts, MBBS, MMed, FRANZCO, FRACS, GAICD, medical director of the Vision Eye Institute and with the Save Sight Institute, University of Sydney (Australia) and colleagues prospectively evaluated all eyes undergoing femtosecond laser cataract surgery (FLACS) with the LenSx FS laser (Alcon Laboratories) between April 2012 and September 2015 at the Vision Eye Institute. (In Australia, patients pay out-of-pocket for the procedure, ranging from $600 to $950; Dr. Roberts’ conversion rates hover around 95%, as his group is known as a specialist laser cataract surgery practice and has a high level of referrals as a result.)

Large cohort study

Large cohort study

In this analysis, 3,842 consecutive procedures were included; in all cases the anterior capsulotomy and lens fragmentation were performed with the LenSx laser, and patients then underwent phacoemulsification and IOL insertion. Intraoperative complications were noted at the time of surgery and collated for analysis.

The main outcome measure was the intraoperative anterior capsule tear rate, Dr. Roberts said.

“It’s important to note that the curved rigid PI was used in 734 cases, and the SoftFit PI was used in the remaining 3,108 cases,” he said, adding the SoftFit software became commercially available in Australia in February 2013.

An anterior capsule tear occurred in 5 cases with the rigid curved interface (0.68%) and 2 cases with the SoftFit PI (0.08%, p = 0.004). These rates are lower than published rates for the manual techniques, he said.

“But what does clinical experience and peer-reviewed literature tell us about anterior capsule integrity after FLACS?” he said. “There is no doubt there will be ultrastructural differences if the capsulotomy is created either manually or with the laser,” Dr. Roberts said. The important question, however, is not what the ultrastructural differences are, but whether there are any relevant clinical implications?

Clinically, the laser creates a “pristine capsule edge, with better geometry and circularity compared to manual capsulorhexis,” he said. In almost all cases, the capsulotomy was free floating, he added.

“Outcomes of larger case series, such as that by the Moorfields’ group [1] and our study,[2] show very lower rates of anterior capsule tears,” he said, citing rates of 0.1% or less for experienced surgeons using different laser platforms.

Advanced software and PI, combined with optimal laser settings and appropriate surgical techniques, “will result in a perfectly circular, evenly sized and intact capsulotomy in nearly every case,” he said.

Surgical pearls

Surgical pearls

Dr. Roberts also offered several surgical pearls to reduce the learning curve in FLACS. Among them: Leave ample time for maximum pupil dilation, and ensure precise positioning and docking.

“Individualize your energy settings, and do a careful inspection of the capsulotomy edge,” he said. Other recommendations include using blue dye to stain white cataracts, and dividing the nucleus into small segments for harder nuclei.

“Don’t bring large nuclear fragments up through the capsulotomy,” he said. “And don’t stretch the capsule edge during cross-action manipulation with the phaco handpiece and side instrument.”

References

1. Day AC, Gartry DS, Maurino V, Allan BD, Stevens JD. Efficacy of anterior capsulotomy creation in femtosecond laser-assisted cataract surgery. J Cataract Refract Surg, 2014;40(12):2031-4

2. Roberts TV, Lawless M, Sutton G, Hodge C.  Anterior capsule integrity after femtosecond laser-assisted cataract surgery. J Cataract Refract Surg, 2015;41(5):1109-10.

None of the physicians in this study have any financial disclosures.