Although it was reported in some older papers that FS laser capsulotomies were associated with an increased risk for anterior capsular tears, an updated Cochrane review including data from 14 randomised controlled trials (RCTs) found no statistically significant difference between the laser technique and manual capsulotomy, said Dr Alex Day, also from Moorfields Eye Hospital.
Dr Day noted that because eye movement affects the accuracy of laser pulse placement, speed of capsulotomy creation is important. He suggested that the fast capsulotomy cut times of approximately one second or less are preferable, and he noted that not all available systems meet that target.
Dr Burkhard Dick, chairman of the University Eye Hospital in Bochum, Germany, and colleagues evaluated other parameters for optimising capsulotomy in studies using a certain system (Catalys Precision Laser System, Johnson & Johnson Vision). In their RCT, they found that vertical spot spacing mattered.1 Increasing the vertical spot separation from 10 to 15 μm improved cut quality and reduced both the number of tags and treatment time.
Results of another RCT by the same group evaluating centration methods favoured OCT-based scanned capsule centration over pupil centration for achieving complete capsule overlap of the IOL optic, independently of IOL design, for up to a 5.1-mm capsulotomy.2 With a 4.7-mm capsulotomy, complete overlap was achieved regardless of centration method and IOL design.
Dr Day noted that there is a trade-off of decreased rim strength with decreasing capsulotomy size. A poll of the attending experts showed that a large majority created a 5-mm capsulotomy for most patients. Others more routinely targeted a smaller diameter, as small as 4.5 mm, but overall, the plan depended on characteristics of the IOL, capsule and/or cataract.
Looking to the future, which will bring new-generation IOLs with smaller optics and the possibility of hanging the IOL optic on a FS laser-created capsulotomy, Dr Stevens raised the possibility of transitioning to smaller capsulotomies.
Dr Day pointed out that ideally the laser should centre the capsulotomy on the visual axis or undilated pupil centre, and the former would necessitate addition of a fixation target.