Ординатура / Офтальмология / Английские материалы / Pediatric Ophthalmology Current Thought and A Practical Guide_Wilson, Saunders, Trivedi_2008

23.1 Introduction

The aim of pediatric cataract surgery is to provide and maintain a clear visual axis and a focused retinal image. The long-term visual outcome is often negatively affected by the development of amblyopia secondary to the cataract itself, or due to postoperative reopacification of the ocular media. Cataract surgery in children remains complex and challenging. One of the major challenges for pediatric cataract surgery has been the adaptation of techniques used for adult cataract surgery. However, pediatric cataract surgery is quite different from surgery for cataracts in the elderly (Figs. 23.1–23.3). A propensity for increased postoperative inflammation and capsular opacification, a refractive state that is constantly changing due to growth of the eye, difficulty in documenting anatomical and refractive changes due to poor compliance, and a tendency to develop amblyopia are among the factors that make cataract surgery in the child different from that in the adult. In addition, the lack of a hard nucleus, vastly reduced scleral and cor-

neal rigidity, and enhanced posterior vitreous pressure demand a surgical approach that differs in many ways from the adult procedure.

23.2Preoperative and Intraoperative Medications

It is important to apply antibiotic drops to the eye prior to beginning surgery. We begin topical application of a fourth-generation fluoroquinolone on checkin approximately 1 h prior to surgery. The drop is given every 5 min for a total of 4 times. While it may be ideal to start the antibiotic earlier than 1 h before surgery, we have found it logistically difficult and have settled for the plan as outlined above.

Dilating drops are also given preoperatively on check-in every 5 min for 3 times. We make up a peds combination drop that consists of 2 mL 2% cyclopentolate, 0.5 mL 10% phenylephrine, and 0.5 mL

Fig. 23.1a–e  Sequence showing cataract surgery without IOL implantation. a Preoperative view of cataract in an infant eye. b Vitrectorhexis. c Dense posterior capsule plaque noticed after removal of lens substance. d Both anterior and posterior

capsulorhexis. Leave behind adequate size of anterior and posterior capsulorhexis to facilitate secondary IOL implantation some years later. e Postoperative appearance of the aphakic eye

1% tropicamide in every 3 mL of drops. In essence, each drop delivered to the patient contains 1.3% cyclopentolate, 1.67% phenylephrine, and 0.17% tropicamide. To aid in maintaining dilation of the pupil throughout surgery, 0.5 mL epinephrine 1:1,000 solution (Hopsira, Lake Forest, IL) is added to each 500 mL bottle of irrigating solution prior to its intraoperative use during surgery. The intraoperative floppy iris syndrome (IFIS) has been reported in adults who take systemic alpha-1 antagonist medications such as tamsulosin (Flomax). IFIS is characterized by progressive pupillary miosis, and a billowing, floppy iris that prolapses easily into even the smallest of surgical entry wounds. It is caused when the pharmacological blockage from Flomax causes the normal dilator smooth muscle tone in the iris to be lost. In children, the dilator smooth muscle tone is reduced naturally, especially in infants with immature microphthalmic eyes. To combat IFIS, pediatric surgeons have used epinephrine in the intraocular irrigating fluid for more than 20 years. We recently published a pediatric case of IFIS in one eye and no IFIS in the other eye as a result of the inadvertent absence of epinephrine in the irrigating fluid of the eye demonstrating signs of IFIS [42]. We strongly recommend epinephrine in the irrigation fluid for all pediatric cataract surgeries.

Povidone iodine, diluted to a 5% solution, is applied to the eye at the end of the surgical skin and lash preparation. An additional drop is placed at the conclusion of surgery. These drops are not irrigated out after application.

23.3 Surgical Steps

23.3.1 Incision

Children have thin sclera and, as mentioned above, markedly decreased scleral rigidity when compared with adults. Scleral collapse results in increased positive vitreous pressure (also known as “vitreous upthrust”). Collapse of the anterior chamber is much more common when operating on pediatric eyes. Pediatric cataracts can be removed through a relatively small wound, as the lens has no hard nucleus. Therefore, wounds should be constructed to provide a snug fit for the instruments that pass into the anterior chamber. When an intraocular lens (IOL) is not being implanted, two stab incisions are usually made at or near the limbus (Fig. 23.1b). These incisions should not be larger than necessary for the instruments being used. For instance, a micro vitreoretinal (MVR) blade can be used that creates a 20-gauge opening for a 20-gauge vitrector/aspirator to enter the anterior chamber. A 20-gauge blunt-tipped irrigating cannula can also be used through a separate MVR blade stab incision. If the instrument positions need to be reversed, the snug fit is maintained. If 23-gauge or 25-gauge instruments are used, an MVR for that gauge opening can be utilized. While some surgeons prefer phacoaspiration (aspiration utilizing a standard phacoemulsification handpiece), a bimanual technique using an irrigating handpiece and a separate aspiration handpiece is preferred by the authors (Fig. 23.1c). Anterior chamber stability is maintained

by limiting wound leak and using a high irrigation setting.

When a foldable IOL is being implanted, a corneal tunnel is preferred since it leaves the conjunctiva undisturbed (Fig. 23.2a–c). The corneal tunnel should begin near the limbus for maximum healing and should be sutured with a synthetic absorbable suture. We prefer to use a marked caliper to outline the dimensions of the tunnel and utilize an angled crescent blade to make a groove and then a tunnel (Fig. 23.2a–c). The blade is turned up on its end to make the groove and then turned over to continue the tunnel (Fig. 23.2c).

Unlike adults, corneal incisions do not usually self-seal in children. Our 2001 survey indicated that only 20% and 3% of the American Society of Cataract and Refractive Surgeons (ASCRS) and American Association for Pediatric Ophthalmology and Strabismus (AAPOS) responders, respectively, left both tunnel and paracentesis incisions unsutured [51]. According to one study [3], self-sealing wounds failed

to remain watertight in children below 11 years of age, especially when an anterior vitrectomy was combined with cataract extraction. In older (>11 years) children the wounds remained self-sealing. Even in these older children, suturing is recommended since postoperative eye rubbing is common. The authors attribute the poor self-sealing to low scleral rigidity resulting in fish mouthing of the wound leading to poor approximation of the internal corneal valve to the overlying stroma. The recommended closure material is a 10-0 synthetic absorbable suture.

In infants, a scleral tunnel is sometimes used because it heals more transparently than a corneal tunnel. In addition, a rigid IOL is implanted occasionally when sulcus placement over a large preexisting posterior capsulotomy is desired. In these instances, a scleral tunnel is utilized. An IOL exchange may require a scleral tunnel if the IOL to be removed is made of poly(methylmethacrylate) (PMMA) (Fig. 23.4). A half-thickness scleral incision is made initially approximately 2 or 2.5 mm from the limbus and dis-

sected into clear cornea. It is enlarged to the size necessary for IOL insertion. Closure is recommended using a 10-0 synthetic absorbable suture. We prefer to suture the wounds and use 10-0 polyglactic acid (Vicryl) absorbable sutures. It takes 60–90 days to completely absorb. Corneal vascularization requiring suture removal is less frequent using Vicryl suture, as opposed to non-absorbable suture (e.g., nylon). The use of non-absorbable sutures occasionally calls for an examination under anesthesia (EUA) for suture removal. Even when economic issues are a deciding factor in choice of suture material, it is better to use absorbable sutures rather than subject the child to additional anesthesia.

While the temporal wound presents the same advantages in children as it does in adults, the location is more easily traumatized by children. The superior approach allows the wound to be protected by the brow and the Bell’s phenomenon in the trauma-prone childhood years. Both scleral tunnels and corneal tunnels can be easily made from a superior approach since children rarely have deep set orbits or overhanging brows. Positioning the patients on the operating table with a slight chin-up posture also helps made the superior approach easier. Locating the site of the tunnel according to the preexisting astigmatism (e.g., temporally in against-the-rule astigmatism) has not been done as often in younger children since most of these patients will wear glasses after surgery anyway. Whether the preoperative astigmatism can be altered by the site of the tunnel incision has not been studied well in children. While wound-related astigmatism is common immediately after surgery in children, due to low scleral rigidity, these eyes tend to return to their preoperative state by 1 month after surgery.

23.3.2 Anterior Capsulotomy

The anterior capsule in children is highly elastic and poses challenges in the creation of the capsulotomy

[45, 48, 52]. While a manual continuous curvilinear capsulorhexis (CCC) is ideal for adults, it is more difficult to perform in young eyes. Overall, the vitrectorhexis is most commonly used in the first few years of life (Fig. 23.1b, d). Manual CCC is used most often in older children. The vitrectorhexis is very stable in the

very young but can tear out to the equator more easily when used in older children (Fig. 23.5).

When performing a manual CCC in a child, the following technical recommendations are offered. Use of a highly viscous ophthalmic viscosurgical device

(OVD) is recommended to fill the anterior chamber and flatten the anterior capsule (Fig. 23.2f). A slack anterior capsule will be easier to tear in a controlled fashion. Re-grasp the capsulorhexis edge frequently and begin with a smaller capsulotomy than desired. Because of the elasticity, the opening will be larger than it appears once the capsular flap is released. In order to control the turning of the CCC edge along a circular path, the tear must often be directed more toward the center of the pupil than would be necessary in an adult eye. If the capsule begins to extend peripherally, stop before the edge is out of sight under the iris. Re-grasp the capsule edge and pull directly toward the center of the pupil to recover the tear. Converting to a vitrectorhexis or a radio frequency diathermy capsulotomy may also be warranted. Using small incision capsulorhexis forceps (Fig. 23.2g) that fits easily through a paracentesis will allow conversion to vitrector instruments when needed without leakage around the vitrector handpiece during use. Recently, modifications of the manual anterior CCC technique have been published and popularized. The most common is called the two-incision push-pull (TIPP) technique. An MVR blade or a cystotome is used to puncture the anterior capsule at the superior and inferior ends of the planned CCC. The superior flap is pushed down and the inferior flap is pulled up until they meet each other. This technique keeps the tearing force directed more toward the center of the pupillary space and less toward the lens equator. The four-incision technique is similar except that four punctures are made initially and all of the ends are connected. These modifications are designed to allow more control of the CCC when the capsule is very elastic [22, 25].

While a CCC using the techniques described above is a reasonable option beyond age 4 years, it will be moredifficultwhenattemptedonchildrenaged4years and younger. The vitrectorhexis is an alternative anterior capsulotomy method that will be more consistently successful than manual CCC in the youngest patients.

The vitrectorhexis has been tested in both laboratory and clinical settings by the authors. This technique has proved to be very effective for young children where the CCC may be difficult to control [41, 43, 44, 48,

52]. When creating a vitrectorhexis (Fig. 23.1b), the following surgical caveats are offered. Use a vitrector supported by a Venturi pump, if possible. Peristaltic pump systems will not cut anterior capsule as easily. A bimanual technique with a separate infusion port is recommended (Fig. 23.1b). Maintain a snug fit of the instruments in the incisions through which they are placed. The anterior chamber of these soft eyes will collapse readily if leakage occurs around the instruments, making the vitrectorhexis more difficult to complete. An MVR blade can be used to enter the eye.

The vitrector and a blunt-tipped irrigating cannula fit snugly into the MVR openings. We recommend either a 20-gauge Grieshaber irrigation handpiece (Alcon)

(Fig. 23.6) or a Nichamin cannula (Storz). Disposable irrigation handpieces from Alcon-Grieshaber are now available as well. These work well and are beginning to replace the reusable type of cannula. An anterior chamber maintainer can also be used if the surgeon prefers. We have found that it is not necessary to begin the capsulotomy with a bent-needle cystotome. Merely place the vitrector, with its cutting port positioned posteriorly, in contact with the center of the intact anterior capsule. Turn the cutter on and increase the suction using the foot pedal until the capsule is engaged and opened. A cutting rate of 150–300 cuts per minute and an aspiration maximum of 150–250 are recommended. These settings are for currently utilized Venturi pump machines. Adjustments may be needed for other machines, especially those utilizing a peristaltic pump.

With the cutting port facing down against the capsule, engage the capsule and enlarge the round capsular opening in a spiral fashion to the desired shape and size. Any lens cortex that escapes into the anterior chamber during the vitrectorhexis is aspirated easily without interrupting the capsulotomy technique. Care should be taken to avoid leaving any

Fig. 23.6a, b  Bimanual irrigation/aspiration handpiece

right-angle edges, which could predispose to radial tear formation. The completed vitrectorhexis should be slightly smaller than the size of the IOL optic being implanted. The vitrector edge in very young children is very smooth as a result of the elasticity of the capsule. In slightly older children, the vitrector creates a slightly scalloped edge but inspection by both the dissecting microscope and the scanning electron microscope has revealed that the scallops roll outward to leave a smooth edge. Any capsular tags or points created at the apex of a scalloped cut from the vitrector are located in an area of low biomechanical stress much like an irregular outside-in completion of a CCC. These tags do not predispose to radial tear formation as demonstrated by finite element method computer modeling [16].

A third option for creating an anterior capsulotomy in a child is available with the use of high-frequency endodiathermy (Kloti radio frequency endodiathermy). This instrument cuts the capsule efficiently but results in an edge that tears easily if stretched. The Fugo plasma blade has also been used to make an anterior capsulotomy. Our experience with the Fugo blade in children is only a few cases, but the capsulotomy edge created in those cases was not very different clinically from that produced by the Kloti instrument mentioned above [48].

The use of capsular dyes has also started attracting the attention of pediatric cataract surgeons

(Fig. 23.7). Visualization of the capsular flap is important to maintain control of any tears and to ensure that the edge is continuous. A report from the American Academy of Ophthalmology has concluded that “it is reasonable to consider the use of dye in cataract surgery in cases in which inadequate capsule visualization or inexperience with capsule visualization may compromise the outcome. The use of dye in routine cases cannot be recommended until a lack of toxicity is more clearly demonstrated in the event of longer duration exposure or posterior segment exposure” [14]. Both trypan blue and indocyanine green dyes provide excellent visualization of the anterior capsule flap during CCC. The United States Food and Drug Administration (FDA) approved use of trypan blue dye in December 2004 specifically as an aid in ophthalmic surgery to stain the anterior capsule of the lens. When injecting under air, the dye should be injected after the paracentesis, but prior to creating the main incision, to help with anterior chamber stability. It has been reported that staining under air versus under OVD has similar efficacy and safety [53]. In addition to better visualization, trypan blue has been reported to minimize epithelial cell proliferation in pediatric cataract surgery [15]. Staining the anterior capsule with trypan blue affected the density and viability of lens epithelial cells (LECs) [24]. The use of dyes is not advised when using hydrophilic IOLs, to avoid permanent discoloration of the IOL

[40].

23.3.3Lens Substance Aspiration (Phacoaspiration)

Thorough removal of lens substance is especially crucial for pediatric eyes. When any cortical matter, which clinically may resemble a harmless strand or fiber, is left behind, it actually leaves behind a large number of mitotically active cells. These cells have the potential to grow and cause a proliferative form of visual axis opacification (VAO). The best means of reducing the incidence of this is to remove as many of these cells as possible at the time of surgery. Since VAO is one of the most frequent postoperative complications in pediatric cataract surgery, meticulous

Fig. 23.7  Trypan blue for better visualization while performing manual CCC in a child with white cataract

removal of the lens substance is a crucial step in the management of pediatric cataracts.

Pediatric cataracts are soft but they may be

“gummy.”Phacoemulsificationisnotneededandmay be harmful in the setting of chamber instability. Lens cortex and nucleus can be aspirated in every case with an irrigation/aspiration or vitrectomy handpiece. We prefer the bimanual approach using separate irrigation and aspiration. Separate irrigation and aspiration help maintain the anterior chamber stability, decrease fluctuations of the anterior chamber, and help thorough removal of lens substance. When using the vitrector, bursts of cutting can be used intermittently to facilitate the aspiration of the more “gummy” cortex of young children. The advantage of using the vitrector is that it is possible to perform vitrectorhexis, irrigation/aspiration, posterior capsulectomy, and vitrectomy all with one instrument (the setting needs to be changed appropriately) (Fig. 23.1). This avoids extra manipulation and repeated entry into and exit from the eye. In older children, after a manual CCC we prefer 20-gauge bimanual irrigation/aspiration handpieces (Fig. 23.6) that are tapered and curved (Alcon/Grieshaber 170-01 for irrigation and Alcon/ Grieshaber 170-02 for aspiration). Nearly identical disposable irrigation/aspiration handpieces are now replacing the reusable instruments mentioned here. We have not noted any technical difference when we use the disposable Alcon/Grieshaber handpieces.

Maintenance of the anterior chamber is critical when removing lens substance. Aspiration of fluid from the anterior chamber must be balanced by adequate infusion. Some surgeons also use Aqualase (Alcon) for phacoaspiration in children. It may have the advantage of better cortical clean-up with fewer mitotically active cells left behind. Further study is needed.

The addition of 0.5 mL adrenaline to the infusion bottle (1:1,000 for cardiac use) helps to maintain mydriasis and perhaps improves iris tissue tone and decreases iris floppiness [42]. Although we do not have personal experience of using heparin sodium in the

irrigating fluid, reports showing a beneficial role in preventingpostoperativeinflammationhaveappeared in the literature [4, 49]. The use of heparin should be avoided in eyes with a compromised blood-aqueous barrier (e.g., previous ocular surgery) as they are at high risk of developing postoperative hyphema.

Hydrodissection has been thought to be less useful in children than in adults. However, one study [39] has shown the intraoperative benefits of performing multiquadrant hydrodissection. The potential benefits are an overall reduction in the operative time and a reduction in the amount of irrigating solution used to facilitate lens substance removal. A fluid wave can sometimes be generated in older children but not reliably in infants and toddlers. Cortical material strips easily from the pediatric capsule even in the absence of hydrodissection if the proper technique is used (Fig. 23.2h). Attempts at hydrodelineation should be discouraged in children since it does not aid in lens removal and may lead to capsular rupture. Hydrodissection should not be done in children with posterior polar cataracts because of the fragility of the posterior capsule in these cases.

23.3.4Posterior Capsulectomy and Vitrectomy

In young children who undergo pediatric cataract surgery, posterior capsule opacification (PCO) is rapid

and virtually inevitable if the posterior capsule is left intact (Figs. 23.8, 23.9) [6, 36, 37]. PCO occurs much faster and is much more amblyogenic in younger children as compared with older children. The advent of vitreous suction cutting devices for removing the center of the posterior capsule and a portion of the anterior vitreous during the initial surgery in young children undergoing cataract surgery dramatically decreased the need for secondary surgery. A primary posterior capsulectomy and anterior vitrectomy during IOL implantation in the pediatric cataract gives the best chance for maintaining a long-term clear visual axis. Neodymium-yttrium-aluminum-garnet

(Nd:YAG) laser posterior capsulotomies are usually necessary in children when the posterior capsule is left intact. Larger amounts of laser energy are often needed as compared to adults, and the posterior capsule opening may close, requiring repeated laser treatments or a secondary pars plana membranectomy.

As of 2008, primary posterior capsulectomy and anterior vitrectomy is common practice while managing younger children with cataract. An important question that remains is, when should the posterior capsule be left intact? We answer this question looking at several factors (age, association of posterior capsule plaque or defect, availability of YAG laser, expected cooperation of child approximately

12–24 months after cataract surgery for YAG). As a rough guideline, in children below 5 years of age, we prefer to do primary posterior capsulectomy and vitrectomy (Figs. 23.1, 23.3). In children, 5–8 years of age, we will do a posterior capsulectomy with or with-

out vitrectomy, as needed. In children above 8 years of age, we keep an intact posterior capsule more often (Fig. 23.2). Anterior segment surgeons are often more accustomed to, and more comfortable with, a limbal (or anterior) approach. Our current strategy is to perform these procedures via the pars plana/plicata preferentially, whenever we intend to use a primary vitrectomy in pediatric eyes receiving IOL implantation (Fig. 23.3). The size of the posterior capsule opening should be large enough to help avoid VAO, but small enough that sufficient peripheral capsular support remains for capsular fixation of an IOL. Even if the surgeon is not planning to implant an IOL in a specific eye, it is important to leave behind sufficient anterior and posterior capsular support at the time of cataract surgery to facilitate subsequent in-the- bag or sulcus-fixated IOL implantation (if needed) (Fig. 23.1d) [33, 50]. Ideally, the surgeon should aim for a central, circular opening in the posterior capsule about 1–1.5 mm smaller than the IOL optic. We use a Venturi vacuum pump system, as in our hands it cuts the capsule more easily than a peristaltic pump. Readers should follow the manufacturer’s instruction manual for using a specific machine and setting.

On the Accurus machine (Alcon Laboratories, Fort

Worth, Texas), an irrigation rate of 30+ cc/min and a cutting rate of 600 cuts/min have proven effective at our setting. When the pars plana/plicata approach is chosen, the IOL should be inserted into the capsular bag using OVD, while the posterior capsule is still intact (Fig. 23.3a, b). The OVD can be removed without fear of engaging vitreous, because removal precedes the posterior capsulectomy. While the irrigation cannula remains in the anterior chamber, an MVR blade is used to enter the pars plana/plicata 2–3 mm (2 mm in patients less than 1 year old, 2.5 mm in patients 1–4 years old, and 3 mm in patients over 4 years old) posterior to the limbus. The vitrector is then inserted through this incision and used to open the center of the posterior capsule. The endpoint for the vitrectomy is difficult to define. Sufficient vitreous should be removed centrally so that the LEC cannot use the vitreous face as a scaffold for VAO. Any vitreous that tracks forward past the plane of the posterior capsulectomy needs to be removed. VAO after primary posterior capsulectomy and vitrectomy is often blamed on an inadequate posterior capsule opening or an inadequate vitrectomy. These assertions have not been verified scientifically. In cataract with as-

sociated blood vessel anomalies, such as persistent fetal vasculature, vitrectomy instrumentation is used to remove the posterior lens capsule, abnormal membrane, and anterior vitreous. Intraocular scissors and intraocular cautery are also used as needed.

Intracameral triamcinolone (Kenalog) may have a potential benefit in the management of pediatric cataract. Kenalog injection into the anterior chamber provides the anterior segment surgeon with a means to localize and identify any vitreous strands remaining in the anterior chamber which otherwise might have gone unnoticed [7]. Sutureless, pars plana vitrectomy through self-sealing sclerotomies has been reported in the literature [5, 8]. No difference in the amount of visible vitreous incarceration between sutured and sutureless sclerotomies was reported, using ultrabiomicroscopy [19]. However, wound leakage, extension, dehiscence, hemorrhage, vitreous and/or retinal incarceration, retinal tear, and dialysis have been reported with this technique. Difficulty with the passage of instruments has also been observed when tunnel incisions are used. A case of successful removal of PCO in a child using a 25-gauge transconjunctival sutureless vitrectomy has been reported

[21]. Although scleral rigidity in children is lower, self-sealing was seen, with the integrity of the eyes well maintained.

23.3.5 Intraocular Lens Implantation

Intraocular lens implantation in children has the benefit of providing, intraocularly, at least a partial optical correction to replace the refracting power of the crystalline lens, which is an important advantage to the visual development in amblyopia-prone eyes.

While there is certainly a benefit to IOL implantation by reducing the dependency on compliance with other external optical treatments (aphakic glasses and contact lenses), implantation in pediatric eyes has remained somewhat controversial. A general consensus exists that IOL implantation is appropriate for most older children undergoing cataract surgery. In contrast, the advisability of IOL implantation during the first year of life is still being questioned. We showed a nearly 5-fold increase in the number of the ASCRS respondents and more than a 13-fold increase in the number of the AAPOS respondents implanting IOLs

in children 2 years old and younger from 1993 to

2001 [51].

It is well known that the majority of the eye’s axial growth occurs during the first 2 years of life. This rapid eye growth makes selection of an IOL power for an infant difficult. Selecting the best IOLpower to implant in a growing child presents unique challenges.

While Gordon and Donzis [11] have documented the axial growth pattern of normal eyes in children, the axial growth of cataractous eyes is different. In the normal phakic child, there is little change in refraction (0.9 diopters from birth through adulthood on average) because the power of the natural lens decreases dramatically as the eye grows axially. However, an

IOL placed in a child’s eye cannot change in power to match the growth of the eye. An IOL chosen for emmetropia in early childhood is likely to leave the patient highly myopic in adulthood. For children beyond the age of 2 years, studies are available to help the surgeon predict average growth of the eye. When operating on children, many surgeons have advised selecting an IOL power that will leave mild to moderate hyperopia, leaving less hyperopia with increasing age (see Chap. 22). Other authors have advocated aiming for emmetropia regardless of age when operating beyond 2 years of age. This approach avoids potentially amblyogenic residual hyperopia but is likely to lead to the development of significant myopia later.

When placing an IOL in a child’s eye, in-the-bag implantation is strongly recommended. Care should be taken to avoid asymmetrical fixation with one haptic in the capsular bag and the other in the ciliary sulcus. This can lead to decentration of the IOL. In contrast to adults, dialing of an IOL into the capsular bag can be difficult in children. Often the IOL will dial out of the capsular bag rather than into it. This tendency can be blunted somewhat by the use of highly viscous OVDs. Foldable hydrophobic acrylic IOLs are used increasingly in children. The AcrySof hydrophobic acrylic IOL (Alcon Laboratories, Fort

Worth, Texas) has been shown to be very biocompatible for pediatric eyes [13, 46, 47]. The one-piece

AcrySof is especially suited for small soft eyes and can be inserted into the capsular bag with ease. We use the AcrySof SN-60-IQ which has a blue-blocker chromophore and is designed using Wavefront technology. It is important to customize the “A”-constant after analysis of your own results. The “A”-constant on the IOL package is calculated using contact “A”-

scan ultrasound globe axial length measurements. We recommend using immersion “A”-scan in children because of higher accuracy. The “A”-constant will usually be higher (by 0.2–0.3) when immersion measurements are used. We utilize a 118.7 “A”-constant for the SN-60-IQ IOL.

While silicone IOLs are infrequently utilized in children, the second-generation silicone material appears to be an acceptable alternative for older children. When capsular fixation is not possible, sulcus placement of an IOL in a child is acceptable. To avoid decentration, a rigid PMMA IOL should be considered or when a foldable lens (such as the three-piece AcrySof IOL) is used, optic capture through the anterior or combined anterior/posterior capsulorhexis should be attempted. Optic capture of an IOL maintained better IOL centration but was reported to predispose to an increased inflammatory response in one study [36].

Some other authors report that although technically challenging, it ensured clear visual axis and centration [9, 10, 12]. The PMMA IOL we prefer is the MC- 60-BM (Alcon Laboratories, Fort Worth, Texas).

Tassignon and colleagues reported the outcome of a surgical procedure they called “bag-in-the-lens” in eyes with pediatric cataract [32]. In this technique, the anterior and posterior capsules are placed in the groove of a specially designed IOL after a capsulorhexis of the same size is created in both capsules [31, 32]. The authors reported a clear visual axis in all pediatric patients with an average follow-up of

17months.

The ongoing development in adjustable IOL tech-

nology may prove very useful in the future of the surgical management of pediatric cataracts. The possibility of a lens that could be adjusted to counter the myopia induced by ocular growth is potentially exciting. An ideal pediatric adjustable IOL implant should be biocompatible, allow for safe repeatable adjustment procedures performed at any time after cataract surgery, and have an adequate refractive error adjustment range. As of today, this ideal adjustable IOL does not exist. However, the concept of such an IOL is being developed and, after certain modifications, such an IOL may become available [26].

The FDA recently approved the Crystalens (Eyeonics), AcrySof ReSTOR (Alcon), and ReZoom (Advanced Medical Optics) IOLs. The Crystalens accommodating IOL is engineered with a hinge designed to allow the optic to move back and forth in