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At Issue: best age and technique for implanting IOLs in pediatric patients
At Issue posed the following question to a panel of experts: “What is the best age to implant IOLs in pediatric patients, and what is your technique and IOL of choice?”
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Contacts, then IOLs
Thomas F. Neuhann, MD: I don’t know if there is a “best” age for pediatric implantation, but I would consider 2 years the earliest age for implantation under “normal” circumstances. The human eye grows rapidly up to age 2 and only minimally thereafter. Therefore, under the aspect of amblyopia prevention – which pediatric cataract surgery and postoperative treatment is all about – implantation before that age does not, in my opinion, make any sense.
Implanting the right lens for about 30 cm to 60 cm, which is a baby’s most important visual distance, will make the child massively myopic with ongoing rapid growth, while it really expands its visual world to farther distances. Making the baby emmetropic miscorrects it for its needs at that time; ongoing myopisation is counterproductive as outlined above.
Undercorrecting the baby, that is, leaving it hyperopic to an arbitrary degree as is often proposed, in order to let the baby “grow into” its refraction, makes the least sense of all. Before it has grown into the correct refraction, it is hyperopic: that is, has no finite distance at which it is in focus. By the time it reaches the refraction — which it does only if the estimation is correct — it is so deeply amblyopic that it doesn’t really need the lens at all anymore.
Overcorrecting the induced refractive deficit with glasses is impractical and optically undesirable. Babies’ eyes are 16 mm to 17 mm long and therefore the remaining hyperopia will be extreme. When overcorrecting with a contact lens, one might as well put the entire refraction into the contact lens and not implant a lens at all into these eyes, which are not only immature optically, but also immature in regard to the collagen and the size, which makes them extremely unsuitable for the implantation of IOLs designed and sized for adult eyes.
I therefore advise contact lens correction up to age 2, and thereafter advise secondary implantation, when the contact lens option is no longer practical. Above age 2 I normally implant primarily for a residual refraction of about –1 D; this covers the widest range of practically useful visual distances and of tolerable aniseikonia — both with progressive glasses for overcorrection and for the usual case of at best occasional overcorrection in the monocular pediatric cataract patient.
It is well understood that this is the rule, for which there are – rarely — exceptions under unusual circumstances.
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Acrylic IOL early
Lucio Buratto MD: Generally speaking, studies confirm that monolateral congenital cataract should be operated within the first 15 weeks of life in order to obtain visual acuity of at least 2/10 after treatment of amblyopia, in the years that follow. With bilateral cataracts, surgery can be performed later, depending on cataract density and the extent of visual impairment.
Since I use foldable acrylic IOLs (Alcon AcrySof MA30BA or MA60BM), I perform a small (2.7 to 3.2 mm) temporal incision in clear cornea. High molecular weight viscoelastic injection combined with viscoadhesive facilitates the stability of the anterior chamber for the capsulotomy. The anterior capsulorrhexis must be large in order to decrease the risk of cellular proliferation and secondary opacification of the anterior and posterior capsules.
In order to create a laminar flow, I use a cannula with a curved tip for hydrodissection and a rectangular hole. In the majority of cases, after hydrodissection, the nucleus and cortex can be removed with an irrigation and aspiration probe, as congenital cataracts are usually soft. In the event of harder cataracts, the nucleus must be fragmented with ultrasound.
In children under 6 years of age, I perform posterior capsulorrhexis and anterior vitrectomy to obtain a clear optical axis and to reduce the need for a second operation. Before IOL fixation I extend the corneal incision to 3.6 mm, and I inject viscoelastic into the capsular bag, making sure that the lens is securely implanted in the bag. I fix the IOL under the edge of the posterior capsulorrhexis; the optic disc is pressed nasally first and then temporally, until it settles down under the posterior capsulorrhexis. This helps keep the visual axis free of opacity. The viscoelastic behind the IOL is left in place, and only the material in front of the IOL is removed after a suture has been applied to the principal incision.
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Depends on the status of the opposite eye
Stephen S. Lane, MD: The best age to implant IOLs in pediatric patients depends on the status of the opposite eye. Infants less than 1 year old with bilateral cataracts undergoing cataract surgery may be left aphakic since spectacles can be successfully worn and secondary implantation performed at a later time. Unilateral cataracts are probably best implanted at the time of cataract surgery to avoid anisometropia and subsequent amblyopia.
Children over age 2 have nearly adult-sized eyes. Studies have shown that axial length and corneal curvature at age 2 or older is close to fully mature and unlikely to significantly change. In my own experience, children over age 2 do extremely well with acrylic posterior chamber IOLs placed within the lens capsule without the need for primary posterior capsulectomy and/or vitrectomy at the time of the original procedure. My experience with these truncated edge acrylic lenses is that posterior capsular opacification, while not being eliminated, is certainly delayed for at least 2 years following implantation. This allows the child a number of opportunities to be seen in the office and feel comfortable with the ophthalmic office setting. Subsequently, if YAG laser should become necessary these children, even at age 4, can successfully undergo the procedure as an adult would.
For children between 1 and 2 years old, early posterior capsular opacification and/or the occurrence of vitreous membranes is quite common. My preferred technique is to place the truncated acrylic lens within the lens capsule and close the wound using several 9-0 Vicryl sutures. Then, using a pars plana approach, a limited vitrectomy is performed as well as a primary posterior capsulectomy using the vitreous cutter. This assures that no vitreous comes forward and that an appropriately-sized posterior capsular opening is made. An injection of sub-Tenon steroid is given at the conclusion of surgery and frequent topical steroids are used in the immediate postoperative period to limit inflammation. This approach is also used for those children with disabilities who cannot or will not be capable of cooperating in the future (eg, a child with mental retardation). While my personal experience is limited in those children less than 1 year old, I would tend to perform cataract surgery, pars plana vitrectomy and posterior capsulectomy, leaving enough posterior capsule to place a secondary IOL at a later age, leaving the patient initially aphakic. However, if this is a unilateral cataract a lens implant should be considered.
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Implant IOL when extracting cataract
Mark Packer, MD: I believe there is a growing body of evidence to support IOL implantation at the time of cataract extraction in the pediatric population regardless of the patient’s age. Early results of the Infant Aphakia Treatment Study reported by Scott Lambert indicate no serious complications, although frequent reoperation (up to 50%) was necessary due to opacities and posterior synechiae. Further, Ed Buckley and Sharon Freedman retrospectively reported a decreased incidence of glaucoma in eyes having primary IOL implantation compared to eyes remaining aphakic or having secondary IOL implantation.
My technique begins with IOL power selection based on keratometry and axial length measurement performed under anesthesia if necessary. Planned overcorrection adjusted for anisometropia is employed to compensate for the expected myopic shift. Alternatively, polypseudophakia with temporary implantation of a sulcus IOL may be appropriate in selected cases. In general I favor a foldable acrylic IOL such as the AcrySof (Alcon) or the Sensar (Allergan).
The irrigation fluid includes 5 units/cc heparin in addition to epinephrine. A clear corneal incision is followed by instillation of viscoelastic and anterior capsular vitrectorhexis. Following aspiration of the cataract the IOL is implanted in the capsular bag. I then initiate a posterior capsulotomy with the cystotome beneath the IOL and perform a limited anterior vitrectomy through the corneal incision. In cooperative patients over age 5 I may defer primary posterior capsulotomy in favor of postoperative YAG capsulotomy. The corneal incision is closed with a single stitch of 10-0 Vicryl. Postoperatively I prescribe a combination antibiotic/steroid ointment and atro pine ointment. I perform retinoscopy at 2 weeks after surgery and prescribe spectacle or contact lens correction as needed.
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Use IOL with lowest inflammatory potential
Priscilla E. Perry, MD, FACS: Unfortunately, the surgeon rarely has the option to decide a preferred age for pediatric cataract surgery. The need for surgery is usually somewhat urgent whether for visual deprivation rehabilitation or secondary to trauma, so there usually is not much choice waiting until the child is older.
If the child is 3 years or older, an IOL would almost always be used because it is difficult to maintain maximal visual rehabilitation with contact lens or aphakic spectacle correction, especially in the case of monocular cataract. Special problems may be encountered in children with chronic inflammatory disease such as juvenile rheumatoid arthritis. Every effort must be made to control this inflammation before and following surgery.
In the infant-to-3 year-old child, the surgical decision is more problematic. Not only are these eyes more technically challenging, but IOL calculation and selection is more inaccurate, since one is trying to predict a future refractive error as well as allow for the rapidly changing current correction. Some have advocated piggyback IOL implantation, with later removal of the anterior IOL, but I have not done this personally. The best choice may be to aim for mild hyperopic overcorrection and use spectacles for “fine-tuning.” The younger the child, the more problematic the care, and I believe a pediatric ophthalmologist should be involved in this situation. Currently there is an Infant Aphakia Treatment Trial in development to help answer these questions.
In considering the IOL type to be implanted, the material with the lowest inflammatory potential is preferred. A heparin surface-modified PMMA lens may be used, especially with trauma, but I would generally choose an acrylic IOL. The lens material performs well from the inflammatory standpoint and minimizes capsule opacification if it is left intact, and a small incision (3.5 mm) can be used. I think this is a distinct advantage in pediatric surgery. Lastly, I would refer the reader to Focal Points, Vol. 17(1), March 1999 by Ed Wilson, MD, for an excellent discussion of this complicated issue.
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The older the better
R. Bruce Wallace III, MD: A general rule of thumb for pediatric cataract surgery is “the older the better.” Children older than 1 year of age stand a better chance of suffering fewer complications during cataract surgery, especially anesthesia complications.
Modern IOL designs and materials allow us to offer safer methods of replacing the cataractous lens with biocompatible materials with good optical quality. For monofocal IOLs, I prefer to use acrylic lenses such as AcrySof and Sensar. Because of low scleral rigidity and possible postoperative eye rubbing, I use a scleral tunnel incision and expect to close these wounds with 10-0 nylon suture. Depending on the age of the child, there may be need for a posterior capsulotomy at the time of surgery and an anterior vitrectomy. This can be followed by the insertion of the optic of the IOL through the posterior capsulotomy leaving the haptics in the bag. I have been surprised at the level of cooperation in older pediatric patients during YAG capsulotomy and therefore reserve this technique generally for patients less than 5 years old.
Multifocal IOLs, like the Allergan ARRAY, have become a popular choice for pediatric patients, especially for monocular cataracts. These lenses can help to preserve stereopsis at near, therefore reducing the possibility of amblyopia and monofixation.
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