Prof. H. Burkhard Dick

home

authors

prof-burkhard-dick

Paediatric cataract is a major cause of visual impairment in young patients worldwide and operating on congenital, early childhood or juvenile cataract is certainly challenging. In the hands of an experienced surgeon and a specialised team, the hurdles posed by the specific conditions of a young, developing eye can be overcome. The bane of the management of paediatric cataract, however, is posterior capsule opacification (PCO), which develops rapidly in the weeks and months after lens removal.

Close to or as much as 100% of young children will develop PCO as the most frequent complication in paediatric cataract surgery. Leaving the posterior capsule intact has been recognised for quite some time as a prerequisite in the pathogenesis of PCO and interventions on the posterior capsule have been introduced as a means to prevent or at least reduce the probability of PCO formation.

The introduction of the femtosecond laser into cataract surgery has been—at least in our view, as pioneers of laser cataract surgery (LCS) in central Europe and with experience of close to 10,000 interventions now—a game changer in many respects, and I had the privilege to describe to readers of 

in the November 2021 issue the potential of its employment in paediatric cataract surgery.

 Readers should be reminded that laser cataract surgery in children is, like so many interventions on our youngest patients, an off-label procedure.

Posterior capsulotomy has been described as an option for reducing PCO formation in paediatric cataract patients. In our experience, primary posterior laser capsulotomy (PPLC) is a completely new approach, not least because an anterior vitrectomy is usually not necessary.

This in turn reduces the risk of one of the most vicious complications of early childhood cataract surgery, aphakic glaucoma, significantly—in fact, to zero. Aphakic glaucoma is one of the most damaging and most difficult-to-manage forms of glaucoma.

In PPLC, the anterior hyaloid membrane of the vitreous stays intact and thus the influence of vitreous substances (which are discussed among the probable causes of aphakic glaucoma) is reduced to nil.

 Overview of the OR setting with the femtosecond laser (Catalys, Johnson & Johnson) within the OR aside the surgical microscope.

When undertaking LCS in paediatric patients, we perform capsulotomy with the laser 

; unlike in adult LCS, the lens is not fragmented because it can usually be removed by aspiration only.

Under general anaesthesia, the child is placed under the laser, then the smaller fluid-filled interface will be slowly and cautiously lowered towards the eye. After gently connecting with the ocular surface, the laser will perform anterior capsulotomy; when entering the clinical data in the platform’s software, we use the Bochum correction formula (described previously2). Anterior capsulotomy is performed and small tags—which appear rarely—are gently removed manually.

The posterior capsule is meticulously polished; in paediatric cataracts, pupil dilation tends to be suboptimal. Ophthalmic viscosurgical device (OVD) is introduced sparingly to avoid pushing the posterior capsular too far back. The posterior capsule is elevated by OVD injection through a small opening in order to change its shape from concave to more convex.

After lens removal under the operating microscope, the young patient is once again positioned under the laser. Primary posterior laser capsulotomy is performed after perfectly aligning the anterior and the posterior capsules. The laser shots are fired from posterior towards anterior.

The BIL implant or BIL lens is a foldable hydrophilic lens, which consists of a biconvex optic and two elliptical plane haptics and is prepared in a cartridge for implantation. In adults, it requires a main incision of about 2.8 mm, but a special BIL lens for paediatric eyes is commercially available, which is smaller than the one implanted in adult eyes and can be exchanged when the child is older.

As first described by Marie-José Tassignon in 2002,

 during bag-in-the-lens (BIL) technique with two well-centred capsulotomies of almost identical size, anterior and posterior capsules are placed in this special IOL’s flange for insertion. We implant the lens by aligning the lower haptic to the 6 o’clock/12 o’clock meridian. A small spatula is used to protect the IOL from coming too deep into the anterior chamber during implantation.

 Paediatric BIL with the anterior and posterior capsule within the “groove” of the optic (view through the microscope). 

When the BIL lens is completely inserted and unfolded, the posterior haptics are placed behind the posterior capsule and the anterior haptics in front of the anterior capsule, which keeps both capsules in the “groove” that is so characteristic of this innovative type of IOL. This procedure allows perfectly centrated and stable positioning of the lens 

Intraoperative use of acetylcholine ensures that the iris covers the haptics. In older children, we make sure the incisions are not leaking; in younger children we use a suture for watertight wound closure.

Minimal remnants of OVD will be resorbed over time.

 Postoperative care is as usual for paediatric cataract patients except for the additional postoperative application of pilocarpine 1% three times daily for 2 days starting directly at the end of the procedure.

PPLC is a generally safe and effective procedure; we have documented its excellent safety profiles after 6 months

 and our 2-year results are currently under review. The same can be said about the BIL technology. A recent publication demonstrated that this implant does not induce an elevated risk for postoperative cystoid macular oedema.

The superiority of secondary bag-in-the-lens implantation over ciliary sulcus implantation of an IOL in aphakic children, in terms of fewer adverse effects, best-corrected visual acuity and IOL centration, was recently described by Liu et al.8 Our opinion that cataract surgery has a great tool promising much lower PCO rates in children than could have been hoped for just a year ago is supported by a 2022 publication from Norway: in 50 eyes of 30 patients younger than 12 years at the time of operation, who had received a BIL since 2013, 92% had a visual axis free of PCO.9

In our experience PCO occurs only if the capsule edges are not positioned in the optic groove between both haptics. This is promising data indeed. And yet, cataract surgery in children is always just the first step on the long and winding road to optical rehabilitation.

Prof. Dick is professor and chair at the University Eye Clinic of Ruhr University, Bochum, Germany. He is consultant on demand for J&J.

1. Vasavada AR, Praveen MR, Tassignin MJ, et al. Posterior capsule management in congenital cataract surgery. 

2. Dick HB. The role of the femtosecond laser in paediatric cataract surgery. 

3. Dick HB, Schultz T. Primary posterior laser-assisted capsulotomy. 

4. Tassignon MJ, de Groot V, Vrensen GF. Bag-in-the-lens implantation of intraocular lenses. 

5. Dick HB, Canto AP, Culbertson WW, Schultz T. Femtosecond laser-assisted technique for performing bag-in-the-lens intraocular lens implantation.

6. Schojai M, Schultz T, Haeussler-Sinangin Y, et al. Safety of femtosecond laser-assisted primary posterior capsulotomy immediately after cataract surgery. 

7. Scheers D, van Os L, Dhubhghaill SN. Clinically significant pseudophakic cystoid macular edema after bag-in-the-lens implantation. 

8. Liu Z, Lin H, Jin G, et al. In-the-bag versus ciliary sulcus secondary intraocular lens implantation for pediatric aphakia: A prospective comparative study. 

9. Boonstra NE, Haugen OH. Bag-in-the-lens intraocular lens in paediatric cataract surgery: intraoperative and postoperative outcomes. 

Articles

Cataract surgery in children is challenging because of the likelihood of posterior capsule opacification. This can be overcome with primary posterior laser capsulotomy coupled with bag-in-the-lens technology.

Preventing posterior capsule opacification in paediatric cataract surgery

Performing cataract surgery on very small children comes with several challenges, partly due to the anatomical peculiarities of an eye that may be just a few weeks old but mainly because the initial operation is usually just the first of numerous interventions that might become necessary over the next couple of years to give the young patient a chance of developing normal, healthy vision. The femtosecond laser, as our considerable experience up to now proves, can play a crucial role in achieving this goal.

And challenges there are indeed. We were one of the first centres to employ the femtosecond laser in paediatric cataract cases, which is, like so many interventions in our youngest patients, an off-label procedure or contraindication for most laser platforms (the Ziemer laser system is the exception because it has a CE mark for laser cataract surgery in paediatric cases).

There are some requirements in paediatric cataract surgery that the surgeon must be aware of before planning the intervention: the surgeon will encounter soft eye tissues, particularly a low scleral rigidity. In addition, the operation and often also pre- and postoperative examinations will have to be performed under general anaesthesia.

There will be a high degree of difficulty in calculating the appropriate IOL power (if IOL implantation is intended). Automated keratometry will be necessary and another consideration is that posterior capsule opacification (PCO) could develop in a relatively short time span after surgery. The occurrence of this complication is almost guaranteed if the posterior capsule is left intact. Finally, the surgeon must be able to perform a vitrectomy.

Intraoperative surgical planning after SD OCT imaging during a paediatric LCS case as a team work collaboration. 

Choosing the best possible time to operate on a newborn or a very young child always means weighing the risks and benefits. After early surgery, massive axial elongation and a substantial myopic shift can be expected.

Operating at a very young age increases the likelihood of the major postoperative complication glaucoma. This and other postoperative complications occur at a much higher incidence when surgery takes place at younger than 4 weeks of age.

Waiting too long, on the other hand, can result in deprivation and consequently in amblyopia. A general recommendation might be—with necessary caution—that unilateral congenital cataract should be operated upon 4–6 weeks after birth and bilateral cataract between 6 and 10 weeks.

We have used the femtosecond laser for paediatric cataract surgery for almost 10 years now and our experience has generally been very positive.

 Unlike in cataract surgery in adults, we do not employ the laser for lens fragmentation (this is done by aspiration) but primarily to achieve a perfect capsulotomy—anterior as well as posterior—which is essential and not only when primary IOL implantation is intended.

With anterior capsulotomy as a crucial step in the operation and for postoperative visual recovery, we were satisfied with even our first paediatric laser cataract surgery cases when we found an optimal circularity of femtosecond-laser-created anterior and posterior capsulotomies.

 As expected, the size of the capsulotomy initially did not turn out as planned because of the aforementioned elasticity. There was considerable widening of the capsule opening immediately after laser treatment.

With growing experience, we found out that, particularly in very young children, the capsulotomy diameter tends to turn out larger than planned. In a clinical series involving 22 eyes of 18 patients, we were able to develop what is now known as the Bochum formula, which has proven its value in correcting for this aberration.

A desired capsulotomy diameter can be achieved using the following formula:

A true bane of paediatric cataract surgery is the high incidence of PCO. A special surgical technique—more for the experienced surgeon than for the newcomer—has the potential to considerably reduce the chances of this complication developing.

First described by Dr Marie-José Tassignon in 2002, during bag-in-the-lens (BIL) technique the anterior and posterior capsules are placed in this special IOL’s flange after creating both an anterior and a posterior capsulotomy with the femtosecond laser. The laser is particularly crucial for creating a perfectly centred posterior capsulotomy.

The IOL used in this technique is a foldable hydrophilic one-piece IOL that is completely inserted and unfolded in the anterior chamber and whose posterior haptics are placed behind the posterior capsule while the anterior haptics are positioned in front of the anterior capsule. This aims to prevent the proliferation and migration of lens epithelium cells over the long term and thus prevent PCO.

The femtosecond laser has the potential to render this manually challenging technique an option for surgeons who have not previously implanted BIL lenses. The femtosecond laser can safely perform the posterior capsulotomy and keep the anterior hyaloid membrane intact.

There are a number of children who have special needs and so it is necessary to make some additional preoperative considerations. A group of young patients with a higher incidence of childhood cataract than the general population are those with Down syndrome.

 have stated based on their surgical experience, cataract extraction in paediatric patients with Down syndrome does not appear to have a higher rate of surgical complications than does cataract surgery in the general paediatric population. There is no reason to assume that laser cataract surgery in these patients might be less effective or less safe than in children without this condition.

Patients with Marfan syndrome may need surgery of the lens when they are not suffering from cataract. Their vision is often compromised by a subluxation of the lens that may render the visual axis aphakic, by irregular astigmatism from the lens periphery and also occasionally from lens opacity.

Lens removal with capsule fixation and IOL implantation is a valuable strategy to address these problems. However, as in the younger patients with congenital cataract, challenges with manual capsulorhexis result from the high elasticity of the capsule (which has a tendency toward posterior tears), damage to the zonules from stress during manipulation, and the fact that the desired position for capsulorhexis is off centre, all too often resulting in increased intraoperative complications for these patients who undergo surgery at a relatively young age.

In one of the first cases ever treated with a femtosecond laser, we operated on a 10-year-old boy with ectopia lentis in both eyes, employing the femtosecond laser in the right eye under general anaesthesia. After the ocular surfaces were identified with the integrated algorithms, the capsulotomy was automatically placed by the software at the centre of the scanned capsule, which was at the superior, temporal periphery of the pupil.

Docking of a right eye with paediatric cataract under sterile conditions using a small personal interface for LCS. 

The selected capsulotomy diameter was 4.1 mm (incision depth: 1,000 μm). No lens fragmentation was performed. The total suction time was 2 minutes and 45 seconds. A microforceps was used to remove the capsular disc and no radial tears were noted. The soft lens was aspirated with standard bimanual irrigation/aspiration devices.

No complications were observed within 10 weeks of follow-up.

 Given the fact that paediatric laser cataract surgery for most laser platforms is off-label, which is quite obviously not a major concern for most manufacturers, there are still shortcomings which will—I hope—be overcome in the near future.

At present, there is no software adapted for posterior capsulotomy, which makes it necessary to position the treatment zones manually. Only two laser platforms (J&J Vision’s and Ziemer’s) currently come with an interface for a smaller eye. There is no special formula for choosing the appropriate IOL for our youngest patients: all of them have been created for adults.

Experience has shown the Barrett formula to be more reliable than other formulas. It is worth noting that the ideal target refraction in very young infants seems to be a slight myopia as they primarily focus on near objects like their toys or their mother’s face.

The operation is the first step to visual recovery for a child with cataract, to be followed by long-term care provided by the ophthalmologist. The parents (or caretakers) must be educated about the need for continuous follow-up so that complications such as inflammation, glaucoma and PCO can be detected and treated as soon as they arise, refractive errors can be corrected and amblyopia therapy can be pursued.

For this first step, we should use all our expertise and (when indicated) the best technology available. In my view, this is—more often than not—the femtosecond laser.

1. Chang P, Lin L, Li Z, et al. Accuracy of 8 intraocular lens power calculation formulas in pediatric cataract patients. 

2. Self JE, Taylor R, Solebo AL, et al. Cataract management in children: a review of the literature and current practice across five large UK centres. 

3. Dick HB, Schultz T. Femtosecond laser-assisted cataract surgery in infants. 

4. Gerste RD, Schultz T, Dick HB. Pediatric cataract surgery with the femtosecond laser. In: Dick HB, Gerste RD, Schultz T (eds.) Femtosecond laser surgery in ophthalmology. Thieme: New York. 2018:162-166.

5. Dick HB, Schelenz D, Schultz T. Femtosecond laser-assisted pediatric cataract surgery: Bochum formula. 

6. Dick HB, Canto AP, Culbertson WW, Schultz T. Femtosecond laser–assisted technique for performing bag-in-the-lens intraocular lens implantation. 

7. Saifee M, Kong L, Yen KG. Outcomes of cataract surgery in children with Down syndrome. 

8. Schultz T, Ezeanosike E, Dick HB. Femtosecond laser-assisted cataract surgery in pediatric Marfan syndrome. 

9. Mohammadpour M, Shaabani A, Sahraian A, et al. Updates on managements of pediatric cataract.

Cataract surgery on very small children presents some unique challenges that can be overcome with the use of a femtosecond laser.

The role of the femtosecond laser in paediatric cataract surgery

Sometimes, a little background music helps one to come to grips with one’s feelings. Whilst I was thinking of a particular patient one day, the juke box in my brain started playing Cher’s 1980s hit ‘If I could turn back time’.

If I had been able to turn the clock back just a couple of weeks earlier, I would have recommended to the 50-something year-old patient, after the initial examination, to go somewhere else, maybe to one of the (very) few colleagues I am not on the best terms with and have that surgeon implant those trifocal IOLs. But time travel being a dream, I undertook the procedure myself and was now facing the consequences.

His vision was 20/20, the IOL could not have been better positioned and there was, two days after the operation of the second eye, not the slightest hint of inflammation. But the patient was, as I now learned, a born complainer – the slight haze really bothered him and the intermediate vision was not as he had hoped it would be. I told myself that a person with such a mentality would probably have been better served with monofocal IOLs (mIOLs). But of course, it was too late.

At least I could counter his complaining over the money he had spent. I showed him the newspaper I had kept, reporting that the United States FDA had approved a gene therapy for the treatment of relatively rare inherited disease – the effects being that the patients were, in some cases, able to put away their navigational canes and recognise the faces of loved ones again.

The price tag was a whopping $850,000 for a one-time treatment. It at least allayed the financial aspect of his discontent.

Reversing the result of an operation has, over the long course of medical history, mostly been tainted by the feeling of failure on the part of the physician. However, in 21st century ophthalmology, with a large segment of the population more demanding than ever before (particularly those interested in refractive surgery), doing some revision or re-adjustment of an earlier intervention is no longer-fortunately-an admission that something went wrong.

It is, rather, a tribute to the sometimes overly high expectations we have to meet – when, for instance, a three-quarter diopter beyond the target refraction is a serious problem, or the challenges of a mIOL turn out to be greater than anticipated. Therefore, it is another milestone in the already breath-taking development of current ophthalmology when postoperative corrections and adjustments become part of our service portfolio.

A couple of years ago, we began implanting light-adjustable IOLs and had satisfying results in patients who were a bit off the desired refractive status. Now, our hopes rest on a new concept, in large part due to the endeavours of Professor Josef Bille and his admirable sense of innovation: refractive index shaping (RIS); if it works in clinical practice as it has so far in experiments, it will not only enable the surgeon to add or distract from the refractive power of an implanted IOL, but also change a multifocal optic into a monofocal, if need be – and back again, if the complaining never stops.

Such readjustments have the potential to satisfy even the most critical patient, maybe even my complainer-in-chief. And the fitting tune to celebrate this development when facing a discontented patient might be Guns N’ Roses’ ‘November Rain’: 

Nothin’ lasts forever, and we both know hearts can change...

Prof. Dick is director and chairman at the University Eye Hospital, Bochum, Germany. Prof. Dick is a member of the 

Author | Prof. H. Burkhard Dick

Articles

Preventing posterior capsule opacification in paediatric cataract surgery

The role of the femtosecond laser in paediatric cataract surgery

Nothing lasts forever