THE HUMAN FACTOR

An intraoperative photo of Dr Dick using the LENSAR Laser System. Couirtesy of H Burkhard Dick, MD, PhD

While the automated technology of the femtosecond laser has simplified and improved the capsulotomy phase of cataract surgery, the surgeon’s skills remain key to optimal outcomes, according to H Burkhard Dick MD, PhD, Chairman and Head of the University Eye Clinic, Bochum, Germany.

“We started to perform femtosecond laser capsulotomy in late 2011, in part because we considered this technology to be able to provide us with a more accurate approach, resulting in more reproducible sizings, shapings and centrations of the anterior capsule. The laser changes this essential step in cataract surgery from tearing (‘-rhexis’) to cutting (‘-tomy’), which is more appropriate for the concept of any kind of surgery,” he told EuroTimes.

Dr Dick was an early adopter of femtosecond laser-assisted cataract surgery (FLACS). He now does 35 per cent of his cases using this approach, using little or no phaco. While acknowledging that there are still questions remaining about the procedure as compared with conventional surgery, he maintains that careful technique will reduce some of the issues reported with the capsulotomy phase of the procedure.

GREATLY IMPROVED

He notes that overall, the quality of femtosecond laser capsulotomies has greatly improved in the last couple of years. The rate of incomplete capsulotomies has gone down from approximately four per cent to less than one per cent. A study by Dr Neil Friedman and colleagues demonstrated that femtosecond laser capsulotomy improved precision in sizing the capsulotomy by 12 times, and improved accuracy in shaping the capsulotomy by a factor of approximately three compared with the manual capsulorhexis technique (JCRS 2011; 37:1189–1198).

He also stressed that the surgeon’s skill still plays a key role. When he first started doing FLACS, he saw four capsular tears in his first 1,273 cases, which included patients with pseudoexfoliation and intumescent cataracts. However, with increasing experience he has been able to reduce the rate of capsule tears to near zero.

“There is, as in any procedure, a learning curve. The incidence of anterior tags, incomplete capsulotomy and, during the manual part, capsular tear, have been shown to greatly decrease with experience. Surgical skill is also required when performing the dimple-down technique, a gentle pulling of the disc centrally or paracentrally to confirm that there is a continuous 360-degree cut with a free disk that we strongly recommend (JCRS 2013; 39:1796-1797). Therefore, the operation's success is still to a greater part dependent on how good the doctor is,” added Dr Dick.

He emphasised that many factors can influence the outcomes of FLACS. Particularly during the laser application, the set-up of the procedure (the systems differ regarding their energy settings, numerical aperture and spacings) plays a role.

“The cooperation of the patient is probably the most important thing. He or she has to lie perfectly still for these few seconds. Movements of the head or the body, coughing and other commotions will negatively affect the quality of the capsulotomy. An optimal positioning of the patient’s head and an adequate sedation – in some patients – are part of the surgeon’s responsibility and, if you will, of his skill in managing not only the procedure but also his patients.”

SPECIAL FEATURES

Special features of the patient's anatomy must also be taken in account. Deep-set eyes or chemosis, for instance, can result in pseudosuction: the interface is not really connected to the globe. This will move on the conjunctiva and a proper capsulotomy may become impossible.

“These situations all prove that the experience and skill of the doctor are – as they have been since the beginnings of medicine – crucial in determining the patient’s well-being, even when assisted by the most sophisticated technology,” he said.

Recent reports have suggested that the capsulotomy edge created with the laser is not as smooth as that seen with manual surgery, with the suggestion that this could account for an increase in the rate of anterior capsule tears. Dr Dick and colleagues recently reported a study looking at this (Schultz T et al., EJO,2015; 25: 112-118). While the capsular edges of continuous curvilinear capsulorhexis were microscopically much smoother than those created with the laser, he does not think it makes a difference in clinical terms.

“Does it make a clinical difference? Not at all, other than supporting the use of the dimple-down technique to detach any tags that might be present. We will certainly see technical enhancements as the laser systems will continually improve, but the microscopic shape of the edges, due to its clinical irrelevance, is not among the most pressing concerns.”

Dr Dick uses the CATALYS platform (AMO) when performing FLACS. He commented that the feature of optical coherence tomography-guidance offered by the system provided a revolutionary new way of treatment by giving the surgeon real-time visualisation.

H Burkhard Dick: burkhard.dick@kk-bochum.de