Reply (2017)

We read with great interest the letter by Dr. Lau and colleagues. To start with terminology, the term primary laser capsulotomy or primary posterior laser capsulotomy should be enough. In addition, what the laser does in laser-assisted cataract surgery is not a capsulorhexis (rhexis from neo-Latin/Greek, meaning tearing) but rather a capsulotomy (from the Greek tomos, meaning to cut).1,2 More important, Dr. Lau et al. address our trial in which only optical coherence tomography scans were taken after redocking to measure intraocular distances at a timepoint at which no one has measured beforehand. Not a single primary posterior laser capsulotomy was performed in our trial. The technique of primary posterior laser capsulotomy has been described in detail and with an accompanying instructional video.3 Suffice to say that there are different options; it can be performed before or after IOL implantation. We clearly favor the version with the IOL already in place (diameter 3.5 mm). The capsulotomy usually is performed at the end of surgery once the eye is watertight. We have not seen anterior chamber flattening or IOL–corneal touch (personal interface 14.1 mm). Some other concerns voiced by Dr. Lau et al. are equally unfounded. There is no “robust pupil alignment” because the posterior capsulotomy can be centered at will and is performed on the IOL optic. The IOL optic is left completely intact because of the large safety zone between the IOL optic and the posterior capsule, which can be increased further if ophthalmic viscosurgical device is left behind the optic. In assessing the potential rate of posterior capsule tears, it is helpful to remember that there are certain differences between the anterior capsule and the posterior capsule. The latter is far thinner and easier to cut and thus is much more likely to be free floating after laser capsulotomy. Tears of the anterior capsule have been described, mainly during phacoemulsification. This is not an issue, however, when we perform primary posterior laser capsulotomy at the end of the procedure. As a consequence, there was not a single radial tear in any of the capsulotomies in our trial. Dr. Lau et al. wonder “[i]f the posterior capsule disk is liberated successfully…how it is removed from the posterior segment.” As described in our article and shown in the figures, the disk is not removed. It curls up, sinks down, and cannot move into the vitreous because the anterior hyaloid membrane is left intact. As of this writing, there have been no reports of floaters or of a patient requiring a PPV. As reported in our article, Berger space was large enough to safely perform primary posterior laser capsulotomy in 72% of cases. Finally, there is no misdirection of fluids because none of the fluids in the anterior chamber are affected by the procedure. Unsuccessful docking can also be ruled out; the intervention occurs after successful docking. The authors claim that in a study from the mid-1990s, only 1.4% of the cataract patients required an Nd:YAG laser posterior capsulotomy. This is a great success that many cataract surgeons in numerous centers around the world probably envy; removal of posterior capsule opacification by Nd:YAG laser capsulotomy is the second most frequent intervention in anterior segment surgery. The United States Medicare database is an immense resource that provides the rates and patterns of surgical practice across a vast population. The database shows that several hundred thousand patients in the U.S. have an Nd:YAG capsulotomy every year.4 We, of course, shared the authors’ concern about long-term consequences such as endophthalmitis and macular edema. After more than 700 primary posterior laser capsulotomies, we did not observe an increased complication rate. Moreover, a prospective randomized intraindividual clinical trial of standard phacoemulsification followed by primary posterior laser capsulotomy or without primary posterior laser capsulotomy was performed with a sufficient power and sample size.5 Therefore, these concerns will certainly be addressed soon in upcoming publications.