Key Features
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Two main approaches are used to remove cataracts in children: pars plana and corneolimbal approach.
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Intraocular lenses, contact lenses, and spectacles are the most readily available means to correct aphakia in children.
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Advances in contact lens technology results in improved visual outcomes.
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Use of intraoperative triamcinolone and better surgical techniques reduces inflammation.
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Postoperative glaucoma remains a major problem.
Introduction
Cataracts in childhood not only reduce vision but also interfere with normal visual development. The management of pediatric cataracts is far more complex than the management of cataracts in adults. The timing of surgery, the surgical technique, the choice of the aphakia correction, and amblyopia management are of utmost importance in achieving good, long-lasting results in children. Children’s eyes are not only smaller than adults’ eyes, but their tissues are much more reactive as well. The inflammatory response to surgical insult seems more pronounced in children, often because of iatrogenic damage to the iris. During the past 2 decades, the refinements that have occurred in adult cataract surgery have contributed to the further development of pediatric cataract surgery (PCS). Certain adaptations and modifications in surgical technique are required to achieve results similar to those achieved in adults. Furthermore, postoperative amblyopia management forms an integral part of visual rehabilitation in children.
Historical Review
Discission of soft cataracts was first described by Aurelius Cornelius Celsius, a Roman physician who lived 2000 years ago. Discission remained the method of choice until the middle of the twentieth century. The technique consisted of lacerating the anterior capsule and exposing the lens material to aqueous humor for resorption and/or secondary washout. Repeated discissions often were required to manage the inevitable secondary cataracts. Many early complications (e.g., plastic iritis, glaucoma, and retinal detachments) were associated with these early techniques. With the advent of vitrectomy machines and viscoelastic substances, as well as the refinements in cataract surgery, these complications have been reduced markedly over the past 2 decades.
Preoperative Evaluation and Diagnostic Approach
A careful history assists the clinician in selecting the investigations needed for determining the cataract’s etiology. Information on problems during pregnancy (e.g., infections, rashes or febrile illnesses, exposures to drugs, toxins, or ionizing radiation) should be elicited. Family history of cataracts in childhood or other ocular abnormalities can be relevant. Both parents and all siblings should be examined with a slit lamp to determine any lens abnormalities. When family history is positive, consultation with a geneticist is recommended. A thorough examination by a pediatrician to assess the child’s general health and to elicit information about other congenital abnormalities may be helpful
Laboratory tests in children who have bilateral cataracts in nonhereditary cases are listed in Box 5.15.1 . Most unilateral pediatric cataracts are idiopathic and do not warrant exhaustive laboratory tests.
Complete blood count
Random blood sugar
Plasma calcium and phosphorus
Urine assay for reducing substances after milk feeding
Red blood cell transferase and galactokinase levels
If Lowe’s syndrome is suspected, screening for amino acids in urine
Toxoplasmosis titer
Rubella titer
Cytomegalovirus titer
Herpes simplex titer
The ophthalmological part of the evaluation starts with a complete ocular examination, which includes an assessment of visual acuity, pupillary response, and ocular motility. Biomicroscopy follows and might necessitate sedation or even general anesthesia in very young patients. Indirect fundus examination with dilated pupils is made unless the cataract is complete. A- and B-scan ultrasonography is carried out in both eyes to compare axial lengths and to discover any posterior segment abnormalities.
Alternatives to Surgery
The development of metabolic cataracts, such as those found in galactosemia, can be reversed if they are discovered in the early phases. With the elimination of galactose from the diet, the early changes in the lens, which resemble an oil droplet in the center of the lens, can be reversed. Later on, lamellar or total cataracts develop and require surgery.
When lens opacities are confined to the center of the anterior capsule or the anterior cortex, dilatation of the pupils with cyclopentolate 1% twice daily can improve vision and postpone the need for surgery. Photophobia and partial loss of accommodation are side effects of this measure.
Anesthesia
General anesthesia is presently the only anesthetic option in PCS. It is extremely important to request deep anesthesia throughout the procedure to minimize iatrogenic damage to iris and cornea. Children’s sclera is particularly elastic; therefore, any tension on the extraocular muscles results in loss of anterior chamber depth and increased intraocular pressure (IOP). A useful marker for anesthesia depth is the position of the eye during surgery. If the cornea moves upward or downward, the anesthesia is too light and should be deepened. When this guidance is followed, surgery is easier to perform.
General Techniques
Unlike in adults, pediatric cataracts are soft. Their lens material can be aspirated through incisions that are 1–1.5 mm long at the limbus or can be subjected to lensectomy through the pars plana. When intraocular lens (IOL) implantation is intended, a larger limbal wound is needed to introduce the IOL. With the use of foldable implants, the incision is not more than 3 mm. A scleral tunnel is better than a clear corneal incision (CCI). Unlike in adults, the wound should be securely sutured with 10.0 vicyrl sutures to prevent wound dehiscence with iris incarceration—a common complication in children.
Specific Techniques
Two main approaches exist for the removal of cataracts in children: the pars plana approach and the corneolimbal approach.
Both techniques have advantages and disadvantages. The pars plana approach was developed with the advent of vitrectomy machines in the late 1970s. It was intended to deal mainly with very young infants in whom surgery is more difficult. With the continuing refinements in cataract and implant surgery in adults, the pars plana approach gradually is being abandoned in favor of the limbal approach because the latter allows better preservation of the capsular bag for lens-in-the-bag IOL placement.
Pars Plana Approach
The pars plana approach is indicated mainly for neonates and infants under 2 years of age, particularly for those who have bilateral congenital cataracts, in which case immediate IOL implantation is not intended. The technique requires a guillotine-type vitrectomy and balanced salt solution (BSS) containing epinephrine (adrenaline) 1:500 000. The location of the pars plana in infants can be 1.5–3.5 mm from the limbus. In the last decade, surgeons have largely abandoned the 20-gauge vitrectomy apparatus in favor of the 23-gauge or the 25-gauge version. A lensectomy–anterior vitrectomy is completed, sparing a 2- to 3-mm peripheral rim of anterior and posterior capsules. These capsule remnants are used to create a shelf to support a posterior chamber IOL that may be implanted later on in life. It is important to avoid vitreous incarceration in the wounds by turning off the infusion before withdrawing the vitrectomy cutter from the eye. This precaution reduces the chances of suffering retinal traction and detachment later in life.
This technique is rapid and allows for a permanently clear visual axis. The postoperative course is normally less complicated than that after the limbal approach because fewer maneuvers occur in the anterior chamber. Consequently, the iris and the corneal endothelium suffer less iatrogenic damage. In cases of children with bilateral cataracts, where an anesthetic risk exists because of unstable medical status, both eyes can be operated on sequentially at the same surgery, but treating both eyes as separate operations. This is now a procedure practiced by some pediatric ophthalmologists even when there is no anesthesia-related risk. This has the additional advantage of reducing the risk of relative amblyopia and freeing up operating room time, thus reducing trauma to the child.
Corneolimbal Approach
The corneolimbal approach is the most widely used surgical technique. A long tunnel limbal incision reduces the risk of iris prolapse. Sometimes, the pupil is meiotic and will not dilate well. This requires intracameral phenylephrine 2.5% and/or iris hooks. Viscoelastic materials are necessary to maintain the anterior chamber depth. Some use an anterior chamber maintainer (ACM) to maintain the chamber, and it can provide a steady intraoperative IOP and helps keep the pupil dilated throughout the procedure because of positive hydrostatic pressure.
Two limbal incisions are made with a 23-g micro-vitreo-retinal blade (MVR; Alcon Laboratories Inc., Fort Worth, TX). These allow for use of a bimanual technique with one cannula infusing fluid to the anterior chamber and the opposite one aspirating the lens material.
Various techniques have been described to open the anterior capsule. The younger the child, the more difficult it is to perform a capsulorrhexis. Infants have a very elastic anterior capsule that easily tears toward the periphery. A manual capsulorrhexis using a push/pull technique has been described. A more practical alternative is to use a vitrectomy probe to create a small central opening in the anterior capsule ( Fig. 5.15.1 ). This hole can be enlarged gradually by biting into the anterior capsule with the vitrector until the desired 4- to 5-mm opening is achieved. Another alternative is the Oertli diathermy system, which has the effect of creating a controlled central 5-mm round capsulectomy ( Fig. 5.15.2 ). Gentle hydrodissection and hydrodelineation free the lens material, which can be aspirated by using the bimanual technique or with the vitrector. The management of the posterior capsular bag is determined by the age of the patient and as to whether an implant should be inserted. Most surgeons agree that infants under 6 years of age should receive an elective posterior capsulectomy and anterior vitrectomy. Posterior capsulorrhexis is performed manually or with a vitrector.
Its diameter should be at least 4 mm ( Fig. 5.15.3 ). The anterior vitrectomy should be generous, removing one third of the vitreous to ensure a permanently clear visual axis. Smaller posterior capsulectomies and shallow anterior vitrectomies close, especially in neonates. Posterior capsulectomies, either alone or combined with shallow anterior vitrectomy, does not guarantee a permanent clear visual axis because lens epithelial cells regrow and can form new membranes.
A modification of the technique includes a translimbal capsulorrhexis and lens aspiration, then insertion of the IOL into the capsular bag. The wound is closed, and the anterior chamber is maintained with either viscoelastic or ACM. The surgeon then goes through the pars plana to perform a posterior capsulorrhexis and anterior vitrectomy by using a vitrector. Leaving the posterior capsule intact, especially in neonates and children under 2 years of age, results in very early posterior capsule opacification. The use of yttrium–aluminum–garnet (YAG), either immediately after surgery or later, has had limited success. Because of logistics, it is not possible unless the surgeon has access to a horizontal laser system.
Pars Plana Approach
The pars plana approach is indicated mainly for neonates and infants under 2 years of age, particularly for those who have bilateral congenital cataracts, in which case immediate IOL implantation is not intended. The technique requires a guillotine-type vitrectomy and balanced salt solution (BSS) containing epinephrine (adrenaline) 1:500 000. The location of the pars plana in infants can be 1.5–3.5 mm from the limbus. In the last decade, surgeons have largely abandoned the 20-gauge vitrectomy apparatus in favor of the 23-gauge or the 25-gauge version. A lensectomy–anterior vitrectomy is completed, sparing a 2- to 3-mm peripheral rim of anterior and posterior capsules. These capsule remnants are used to create a shelf to support a posterior chamber IOL that may be implanted later on in life. It is important to avoid vitreous incarceration in the wounds by turning off the infusion before withdrawing the vitrectomy cutter from the eye. This precaution reduces the chances of suffering retinal traction and detachment later in life.
This technique is rapid and allows for a permanently clear visual axis. The postoperative course is normally less complicated than that after the limbal approach because fewer maneuvers occur in the anterior chamber. Consequently, the iris and the corneal endothelium suffer less iatrogenic damage. In cases of children with bilateral cataracts, where an anesthetic risk exists because of unstable medical status, both eyes can be operated on sequentially at the same surgery, but treating both eyes as separate operations. This is now a procedure practiced by some pediatric ophthalmologists even when there is no anesthesia-related risk. This has the additional advantage of reducing the risk of relative amblyopia and freeing up operating room time, thus reducing trauma to the child.
Corneolimbal Approach
The corneolimbal approach is the most widely used surgical technique. A long tunnel limbal incision reduces the risk of iris prolapse. Sometimes, the pupil is meiotic and will not dilate well. This requires intracameral phenylephrine 2.5% and/or iris hooks. Viscoelastic materials are necessary to maintain the anterior chamber depth. Some use an anterior chamber maintainer (ACM) to maintain the chamber, and it can provide a steady intraoperative IOP and helps keep the pupil dilated throughout the procedure because of positive hydrostatic pressure.
Two limbal incisions are made with a 23-g micro-vitreo-retinal blade (MVR; Alcon Laboratories Inc., Fort Worth, TX). These allow for use of a bimanual technique with one cannula infusing fluid to the anterior chamber and the opposite one aspirating the lens material.
Various techniques have been described to open the anterior capsule. The younger the child, the more difficult it is to perform a capsulorrhexis. Infants have a very elastic anterior capsule that easily tears toward the periphery. A manual capsulorrhexis using a push/pull technique has been described. A more practical alternative is to use a vitrectomy probe to create a small central opening in the anterior capsule ( Fig. 5.15.1 ). This hole can be enlarged gradually by biting into the anterior capsule with the vitrector until the desired 4- to 5-mm opening is achieved. Another alternative is the Oertli diathermy system, which has the effect of creating a controlled central 5-mm round capsulectomy ( Fig. 5.15.2 ). Gentle hydrodissection and hydrodelineation free the lens material, which can be aspirated by using the bimanual technique or with the vitrector. The management of the posterior capsular bag is determined by the age of the patient and as to whether an implant should be inserted. Most surgeons agree that infants under 6 years of age should receive an elective posterior capsulectomy and anterior vitrectomy. Posterior capsulorrhexis is performed manually or with a vitrector.
Its diameter should be at least 4 mm ( Fig. 5.15.3 ). The anterior vitrectomy should be generous, removing one third of the vitreous to ensure a permanently clear visual axis. Smaller posterior capsulectomies and shallow anterior vitrectomies close, especially in neonates. Posterior capsulectomies, either alone or combined with shallow anterior vitrectomy, does not guarantee a permanent clear visual axis because lens epithelial cells regrow and can form new membranes.
A modification of the technique includes a translimbal capsulorrhexis and lens aspiration, then insertion of the IOL into the capsular bag. The wound is closed, and the anterior chamber is maintained with either viscoelastic or ACM. The surgeon then goes through the pars plana to perform a posterior capsulorrhexis and anterior vitrectomy by using a vitrector. Leaving the posterior capsule intact, especially in neonates and children under 2 years of age, results in very early posterior capsule opacification. The use of yttrium–aluminum–garnet (YAG), either immediately after surgery or later, has had limited success. Because of logistics, it is not possible unless the surgeon has access to a horizontal laser system.
Choices for Correction of Aphakia in Children
Spectacles, contact lenses, and IOLs are the most readily available means to correct aphakia in children.
Spectacles
Aphakic spectacles provide satisfactory correction only in cases of bilateral aphakia in which anisometropia does not represent a problem. Most of the patients develop good visual acuity with the use of spectacles, provided that the eyes are not excessively microphthalmic. The disadvantages of spectacles are cosmetic concerns and the poor optical quality of high-plus lenses.
Contact Lenses
During the 1970s and 1980s, contact lenses were described as the method of choice to correct unilateral and bilateral aphakia in childhood. Contact lenses provide better optical correction compared with spectacles, and their dioptric power can be adjusted throughout life. However, the management of contact lenses in children can be very difficult and costly because of frequent loss of lenses, recurrent infections, and poor follow-up. The Infant Aphakia Treatment Study (IATS) was a multicenter randomized clinical trial comparing cataract surgery with or without IOL implantation in infants ages 1–6 months with clinical congenital cataracts. The IATS authors concluded that there was no significant difference in the median visual acuity between eyes that underwent primary IOL implantation and those left aphakic. However, significantly more adverse events occurred, and a need existed for additional intraoperative procedures in the IOL group. Those authors concluded that primary IOLs should be reserved for those cases where, in the opinion of the surgeon, the use of handling of a contact lens would result in significant periods of uncorrected aphakia. During the last 2 decades, many technical problems have been overcome. One such recent advance is the introduction of extended wear silicone elastomer and custom rigid gas permeable contact lenses that are a great advance. Some problems, such as cost of replacement and need for frequent replacement because of changes in refractive error and lens loss, have persisted.
Intraocular Lenses
The IOL option was originally advocated in cases of unilateral pediatric cataracts because it facilitates amblyopia management by providing more permanent correction. Implanting an IOL in a growing eye is not an ideal solution. The aim in the IOL option, unlike in the contact lens alternative, is to correct most, but not all, of the aphakia; the residual refractive error has to be corrected with the use of spectacles, which can be adjusted throughout life.
The implantation of anterior chamber angle supported IOLs in children was discontinued in the mid-1980s. Devastating complications, such as secondary glaucoma and corneal decompensation, were attributed to these IOLs, especially in younger patients. Posterior chamber intraocular lens (PCL) implantation represents, by far, the best method for the correction of aphakia.
Selection of Intraocular Lenses
The choice of the dioptric power of IOL for young children is the main difficulty faced by the ophthalmologist. Pediatric IOLs are not yet readily available, and the rapid growth of the eye during the first 2 years of life makes an effective choice difficult ( Box 5.15.2 ). Nevertheless, in the 1990s, increasingly positive reports were published on the use of PCLs in children and even in neonates.
