23 Pediatric Cataract Surgery with the Femtosecond Laser
Summary
The femtosecond laser has successfully been employed in a number of cases of pediatric cataracts (where it is used as an off-label procedure). The surgeon faces a number of anatomical challenges and has to deal with, for instance, small pupils and tight palpebral fissures. Unlike in adult femtosecond laser–assisted cataract surgery, we are not performing lens fragmentation with the laser, but use the laser solely for capsulotomy. The capsulotomy diameter turned out to be larger than intended in most of the cases—an enlargement that depends on age: the younger the patient, the more pronounced the enlargement. As a consequence, the Bochum correction formula has been developed, which is a valuable tool to achieve exact precalculated anterior and posterior capsulotomy diameters.
Keywords: bag-in-the-lens technique, Bochum formula, capsulotomy, congenital cataract, continuous curvilinear capsulorhexis, pediatric cataract
23.1 Introduction
There is one group of patients in which the cataract surgeon’s care takes on a completely new dimension: the youngest. Boys and girls with pediatric cataract—whether their lens opacification is congenital or acquired, whether they will undergo surgery at an age of 3 weeks, 3 months, 3 years, or as a young (almost) adult at age 17 years—will bear the results of the cataract surgeon’s endeavors for an entire lifetime. 1 Given current life expectancies in the industrialized world, this means probably for 70 to 80 years. It is thus of prime importance to provide these young patients with the best we can offer them.
There are indications that the femtosecond laser can contribute to this essential state-of-the-art management. However, it must be added that only the first steps of this new treatment option have been taken. The experience in femtosecond laser in treating the cataract of babies, children, and teenagers are limited. And it must be pointed out that it is an off-label procedure—as it is so often the case when doctors treat children, in ophthalmology and in other medical disciplines.
While relatively rare in Europe and North America, childhood cataract is responsible for about 10% of all blindness worldwide, mainly due to lack of necessary ocular surgery infrastructure in some parts of the world. 2 Pediatric cataract surgery requires meticulous planning, not the least with regard to its timing: delaying an operation or having the patient diagnosed too late might impair the child’s visual development. The surgeon must be ready to meet the difficulties presented by infants and children among which are the following:
Soft eye tissues, particularly a low scleral rigidity.
Examining the eye preoperatively and postoperatively as well as operating under general anesthesia.
The difficulty of calculating intraocular lens (IOL) power and the need for automated keratometry and A scan in the operating room.
Being able to perform vitrectomy.
The postoperative requirement for correction of the residual refractive error and possibly amblyopia prophylaxis.
Whether bilateral cataracts should be operated simultaneously has been a matter of intense debate for quite a while. Arguments in favor of removing both cataracts in one session are a reduction of the anesthesia-related risk of complications, the reduction of hospital admissions, and the chance to achieve an improved visual acuity and binocular vision faster. Medicolegal reasons are points made against simultaneous surgery as are the risks of bilateral postoperative complications like an endophthalmitis and the inability of the physician to change his or her surgical plans for the second eye if complications should arise over time after surgery of the first eye. 3
In femtosecond laser–assisted pediatric cataract surgery, the laser system has been employed for two of the most crucial steps: anterior and posterior capsulotomies. Due to the often soft lenses in children’s eyes, it was not employed for lens fragmentation.
There are a number of requirements for the setting as well as for the team when it comes to femtosecond laser cataract surgery in infants. It is a prerequisite to have the laser system in the operating room—as a tool in a completely sterile procedure (▶ Fig. 23.1). 4 These are essential conditions, particularly if re-docking to the laser becomes necessary during the procedure. The climate control system of the room has to be sufficient and there has to be enough space for an addition to the usual surgical team: the anesthesiological team and their dedicated equipment.
Fig. 23.1 Setup in pediatric laser-assisted cataract surgery. The laser is positioned in the operating room.
Performing the anterior capsulotomy with the laser in pediatric cases will probably be appreciated by every surgeon who ever tried manual continuous curvilinear capsulorhexis (CCC) in infants and small children. Their capsule tends to be extremely elastic and their intravitreal pressure much larger than can be expected in an adult. Furthermore, children’s pupils in general dilate rather poorly. Manual CCC thus is quite difficult in children. Besides the capsule’s elasticity, the vitreous pressure that moves the entire lens anteriorly contributes to the problems that can lead to the “runaway rhexis,” an inadvertent extension out to the lens equator. The failure rate to create an intact CCC has been reported by Vasavada et al to be up to 80%. 5
Since none of the femtosecond laser systems were created for the treatment of small children, placing the interface between the laser and the globe sometimes requires a small superficial lateral canthotomy. Fortunately, at least one company so far has introduced a smaller interface especially for patients with tight palpebral fissure with a diameter of 12 versus the regular 14.1 mm (▶ Fig. 23.2, ▶ Fig. 23.3).
Fig. 23.2 Fluid-filled patient interface. Inner diameter of 12 and 14.1 mm.
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