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Silicone intraocular lens implantation in children: preliminary results1
Silicone intraocular lens implantation in children: Preliminary results Sima Pavlovic, MD, Felix K. Jacobi, MD, Michael Graef, MD, Karl W. Jacobi, MD ABSTRACT Purpose: To evaluate the safety and outcome of foldable silicone intraocular lens (IOL) implantation in children. Setting: Department of Ophthalmology, University of Giessen, Giessen, Germany. Methods: The results of cataract extraction and silicone IOL implantation in children having surgery between 1992 and 1997 were retrospectively analyzed in 8 eyes (7 patients). All IOLs were implanted in the capsular bag through a 3.5 mm clear corneal incision. In 4 eyes, primary posterior capsulectomy and anterior vitrectomy were performed. Results: Mean patient age at the time of surgery was 5.1 years (range 8 months to 15 years). The surgeries were uneventful. All IOLs remained anatomically stable and well centered during the mean follow-up of 29.6 months (range 18 to 46 months). Postoperative inflammatory reaction was minimal. Neither fibrinoid exudation nor posterior synechias occurred postoperatively. Postoperative best spectacle-corrected visual acuity ranged from 20/800 to 20/20. All eyes with an intact posterior capsule developed posterior capsule opacification. In the 4 eyes that had primary posterior capsulectomy and anterior vitrectomy, the visual axis remained clear. Conclusions: These preliminary results suggest that silicone IOL implantation in children is a safe procedure with good and stable short-term anatomic results. Longer follow-up is necessary to answer questions about the long-term safety of silicone lens implantation in a child’s eye. J Cataract Refract Surg 2000; 26:88 –95 © 2000 ASCRS and ESCRS
C
ataract extraction with primary intraocular lens (IOL) implantation in children has became more popular in the past decade but still remains a challenge for many ophthalmic surgeons.1 The functional result after pediatric cataract surgery depends not only on the anatomic success of the operation and postoperative maintenance of a clear optical axis but even more on aphakic visual rehabilitation. Conventionally, optical correction is achieved by spectacles or contact lenses.2,3
Accepted for publication September 21, 1999. Reprint requests to Sima Pavlovic, MD, Department of Ophthalmology, Friedrichstrasse 18, 35392 Giessen, Germany. © 2000 ASCRS and ESCRS Published by Elsevier Science Inc.
The success of both relies significantly on parental compliance and the child’s acceptance.2–5 Intraocular lens implantation is theoretically superior to spectacle and contact lens use because it provides almost immediate optical correction that is significantly more reliable because it does not depend on parent or child compliance. Still, there are many controversies about IOL implantation in infants and young children, including IOL size,6 material,6,7 and power calculation8,9; prevention and management of the after cataract10 –14; and the long-term safety of IOLs in the child’s eye. In most reported pediatric cataract cases, poly(methyl methacrylate) (PMMA) IOLs were implanted. 0886-3350/00/$–see front matter PII S0886-3350(99)00333-8
SILICONE IOL IMPLANTATION IN CHILDREN
To our knowledge, primary silicone IOL implantation in infants and young children has not been reported. In 1992, we began primary implantation of silicone IOLs in selected cases of pediatric cataract. We analyzed these cases retrospectively to evaluate postoperative anatomic and functional results as well as complication rates.
Patients and Methods Between 1992 and 1997, cataract extraction and primary silicone IOL implantation were performed in 8 eyes (7 patients) with pediatric cataract. Preoperatively, a detailed history was taken including duration of ocular complaints and birth and family data. Other information obtained was age, sex, visual acuity with or without correction (when possible), slitlamp examination, indirect ophthalmoscopy, presence of squint, and ocular fixation. In older cooperative children, keratometry, intraocular pressure, and axial length measurements were performed in both eyes preoperatively. In younger uncooperative children, IOL power was calculated echographically after keratometry and a thorough examination under an operating microscope. In addition, applanation tonometry and indirect ophthalmoscopy were performed using general endotracheal anesthesia. Keratometry was obtained using the portable handheld auto keratometer, autorefractometer (Retinomax-Plus, Nikon), or both. The type of cataract extraction, intraoperative complications, and all surgical procedures were noted, including IOL style and haptic location as well as management of the posterior capsule and vitreous. Information on the best corrected visual acuity (BCVA) (when possible), refractive error, ocular fixation, and ophthalmic findings with slitlamp, tonometry, and indirect ophthalmoscopy was recorded at postoperative examinations. Recognition visual acuity was determined using optotypes. If the determination of recognition visual acuity was impossible because of poor cooperation, resolution acuity was assessed using the Teller acuity card tests (preferential looking). In younger uncooperative children, at least 1 examination using general endotracheal anesthesia was performed postoperatively under the operating microscope, including applanation tonometry, indirect ophthalmoscopy in mydriasis, and refraction of both eyes by retinoscopy, the portable handheld autorefractometer, or both. Other postopera-
tive data included duration of follow-up, reasons for poor BCVA, and subsequent postoperative procedures (e.g., capsulotomy, suture removal). Preoperatively, pupils were dilated with phenylephrine hydrochloride 5%, cyclopentolate hydrochloride 1%, tropicamide 0.5%, and flurbiprofen sodium 0.03% eyedrops. All children had surgery under general endotracheal anesthesia. Detailed informed consent was obtained from each child’s parents after they had been fully informed about the nature and risks of the procedure; the unknown long-term risks associated with silicone IOL implantation in children were emphasized. In all cases, the opaque lens was removed through 2 paracenteses, followed by IOL implantation through a 3.5 mm clear corneal incision at the superior limbus. Two paracenteses were made with a stiletto knife at 10 and 2 o’clock. If the pupil was not sufficiently dilated, 0.5 cc of preservative-free epinephrine 1:10000 was injected into the anterior chamber. The anterior chamber was filled with a highly viscous viscoelastic substance (Healon GV威). A vitrector with side-port cutting capability and a diameter of 0.6 mm was used to perform a nearly circular anterior capsulectomy in 6 cases. Irrigation was provided by the irrigation device through the second paracentesis. Continuous curvilinear capsulorhexis (CCC) was performed using a cystotome needle in 2 eyes. After anterior capsulectomy, the lens nucleus was removed using the vitrector, combining aspiration and cutting. The residual cortex was removed through the 2 paracenteses using the bimanual irrigation/aspiration (I/A) device. After the anterior chamber was refilled with viscoelastic substance, a 3.5 mm wide and 1.5 to 2.0 mm long 3-step clear corneal incision was made at the superior limbus. A silicone IOL was folded and implanted under viscoelastic material through the clear corneal tunnel. The IOL was inserted with the leading haptic followed by rotating the trailing haptic into the capsular bag. In all cases, a 3-piece biconvex silicone IOL with a 6.0 mm optic and 13.0 mm overall length was used. In 4 eyes, an IOL with PMMA loops was implanted (SI40NB, Allergan Medical Optics) and in 4 eyes, an IOL with polypropylene loops (SI-30NB, Allergan Medical Optics). The corneal incision was sutured with interrupted 10-0 monofilament nylon sutures in 5 eyes or a 10-0 polyglactin suture (Vicryl威) in 3 eyes.
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After IOL implantation, primary central posterior capsulectomy and shallow anterior vitrectomy were performed bimanually in 4 patients by introducing the vitrector through 1 paracentesis behind the IOL optic. Irrigation was provided by the irrigation device through a second paracentesis. The viscoelastic material was then completely removed from the anterior chamber with a bimanual I/A device. The pupil was constricted with intracameral carbachol 0.01%. The paracenteses were closed by hydrotamponade. If either paracentesis was leaking, an additional interrupted 10-0 suture was placed at this site to ensure a watertight wound. All patients received broad-spectrum antibiotics intravenously at the time of surgery. Subconjunctival gentamicin sulfate (10 mg) and dexamethasone sodium phosphate (2 mg) were administered at the end of the surgery. Postoperatively, the eyes were treated with topical dexamethasone 0.1% and neomycin sulfate 0.5% 6 times daily and flurbiprofen 4 times daily. Patching for amblyopia was instituted when indicated, depending on the fixation preference, visual acuity, or both.
Results At the time of surgery, mean patient age was 5.1 years (range 8 months to 15 years). The timing of the cataract extraction was primarily determined by the patient’s referral to the clinic. All but 1 child were older than 1 year at presentation. Most patients presented without adequate records of previous examinations; in many cases it was not possible to establish the age of cataract onset with certainty. Mean follow-up was 29.6 months (range 18 and 46 months). Patient demographics are shown in Table 1. Morphologically, nuclear cataract was most common. In 4 of 7 patients, the cataract was bilateral (Table 2). In 1 patient, a persistent hyaloid artery was present. Three patients had strabismus preoperatively. In 1 patient, a silicone IOL was implanted bilaterally. In 3 other patients with bilateral cataract, a single-piece PMMA IOL was implanted in the fellow eye. The targeted postoperative refraction was ⫹3.00 diopters (D) in children younger than 2 years, ⫹2.00 D in children between 2 and 4 years, and emmetropia in children older than 5 years. Table 3 shows the functional 90
Table 1. Patient demographics.
Sex
Age (Years)
Follow-up (Months)
1
F
8.5
46
2
M
2.0
34
3
M
3.4
32
4
M
4.7
35
5
M
0.7
18
6
M
1.4
33
7
F
15.0
20
8
F
15.0
19
Case
Table 2. Types of cataract.
Case
Cataract Type
Cataract Presence
1
Total
Unilateral
Clear lens
2
Total
Bilateral
PMMA IOL
3
Nuclear
Bilateral
PMMA IOL
4
Nuclear
Bilateral
PMMA IOL
5
Nuclear
Unilateral
Clear lens
6
Nuclear⫹P.Lent⫹PHA
Unilateral
Clear lens
7
Nuclear
Bilateral
Silicone IOL
8
Nuclear
Bilateral
Silicone IOL
Fellow Eye
P.Lent ⫽ posterior lentiglobus; PHA ⫽ persistent hyaloid artery; IOL ⫽ intraocular lens
outcomes and the predicted and obtained postoperative refractions. Postoperative best spectacle-corrected visual acuity ranged from 20/800 to 20/20. Postoperative visual acuity could not be assessed in 1 child with trisomy 21 because of mental retardation. Visual acuity improvement after cataract extraction depended on the type of cataract (bilateral or unilateral) and timing of the cataract surgery. Visual acuity was worse in children with unilateral congenital cataract. Three patients had severe amblyopia in the operated eye (visual acuity 20/200 or less), diagnosed on the basis of a poor fixation pattern in the presence of clear media and evident normal anterior and posterior segments. In all 3 patients, the cataract was unilateral and surgery was performed after they were 8 months old (range 8 months to 8.5 years). Deprivation amblyopia was thought to be present before surgery in 4 eyes. For 5 eyes, occlusion therapy was prescribed post-
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Table 3. Postoperative acuities and refractions. Postoperative BSCVA
Refraction (SE) (D)
Case
Preoperative BSCVA
Operated Eye
Fellow Eye
Operated Eye
Fellow Eye
1
HM
20/800
1.2
⫺0.25
⫹0.90
2
NP
NP
NP
⫹1.50
⫹2.00
3
20/400
20/50
20/32
⫹3.00
⫹1.75
4
20/200
20/63
20/200
⫹0.50
⫺2.00
5
NP
20/200
20/50
⫹2.00
⫹0.50
6
NP
20/800
20/20
⫺0.75
⫹0.25
7
0.3
20/25
—
⫺1.00
—
8
0.3
20/20
—
⫺0.50
—
BSCVA ⫽ best spectacle-corrected visual acuity; HM ⫽ hand movements; NP ⫽ not possible; SE ⫽ spherical equivalent
operatively; of these, 2 showed good compliance based on parental reporting. In all patients, cataract surgery and IOL implantation were uneventful. All IOLs were implanted in the capsular bag. Postoperative inflammatory reaction was minimal. Neither fibrinoid exudation nor posterior synechias were seen postoperatively. All IOLs were well centered and remained anatomically stable during the follow-up. No pigment or cell deposits were seen on the IOL surface. All 4 eyes with an intact posterior capsule developed functionally significant posterior capsule opacification (PCO). Surgical capsulotomy with anterior vitrectomy was performed using general anesthesia in 2 cases because the children did not cooperate during an attempt to perform a neodymium:YAG (Nd:YAG) laser capsulotomy. An Nd:YAG capsulotomy was performed in 2 eyes. Mean time between cataract surgery and capsulotomy in eyes with a silicone IOL was 10.25 months (range 7 to 15 months). One of the 3 fellow eyes with PMMA IOLs required surgical capsulotomy and anterior vitrectomy because of PCO that developed 13 months after cataract surgery. (The fellow eye with a silicone IOL developed PCO after 15 months.) In 2 other fellow eyes with a PMMA IOL, primary posterior capsulotomy and anterior vitrectomy were performed during cataract surgery. These 2 eyes did not develop PCO. One eye with a PMMA IOL developed postoperative pigment deposits on the IOL surface and tiny posterior synechias on the anterior capsule. The remaining 3 fellow eyes with a PMMA IOL did not have postoperative complications.
In all 4 eyes with a silicone IOL that had primary posterior capsulectomy and elective anterior vitrectomy during cataract surgery, the visual axis remained clear during the follow-up. The IOLs remained well centered despite the large posterior capsule opening in all patients. In 1 patient, squint surgery was performed 15 months after cataract surgery. In 4 eyes, the corneal suture was removed (in 2 children using general anesthesia and in 2 at the slitlamp using topical anesthesia). No eye developed glaucoma postoperatively. In 4 uncooperative children at least 1 examination, including applanation tonometry and indirect ophthalmoscopy, was performed postoperatively using general anesthesia. No eye developed corneal or macular edema, hyphema, or retinal detachment.
Discussion Cataract surgery and IOL implantation in infants and young children have improved over the past few decades. However, the elasticity of the sclera and the small eye of the child make cataract extraction significantly more difficult than in adults. Surgery is frequently accompanied by vitreous pressure and a shallow anterior chamber, which increase trauma to the iris and corneal endothelium and cause a more pronounced postoperative inflammatory reaction. In the current study, these problems were solved by removing the opaque lens through 2 paracenteses using bimanual I/A or irrigation/vitrectomy, as well as implanting a foldable IOL through a 3.5 mm corneal incision. Filling the anterior chamber with a highly viscous
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viscoelastic material counteracts the vitreal pressure and facilitates instrument and IOL insertion in the anterior chamber. The viscoelastic substance remains in the anterior chamber during the entire procedure. Bimanual I/A kept the anterior chamber formed and reduced the instruments’ contact with the corneal endothelium and the iris. The capsule’s extreme elasticity, increased intravitreal pressure, and small eye in infants and young children make manual CCC difficult. The leading edge of the CCC tends to extend outward, and capsulotomy size is difficult to control. Mechanized capsulectomy using bimanual irrigation/vitrectomy results in smooth, slightly scalloped capsulectomy edges that are not sharp or broken.15 As shown by Wilson and coauthors15,16 and Wang et al.,17the method of anterior capsulectomy used in our study does not cause radial tears, which can also be avoided by maintaining a circular capsulectomy. According to our clinical experience, this anterior capsulectomy configuration is stable during subsequent foldable IOL implantation. In our series, no radial tears developed intraoperatively. Performing anterior capsulotomy and lens removal in the closed eye through the 2 paracenteses controlled vitreal pressure and maintained a deep anterior chamber throughout surgery in all 7 patients. All eyes had a low postoperative inflammatory reaction and a clinically well-centered IOL. We believe this is not directly the result of the silicone IOL but rather of the small incision cataract surgery. In infants and young children, we recommend using a suture even with a small tunnel incision. We advise using a 10-0 polyglactin suture in small uncooperative children, eliminating the need for later suture removal. Anterior capsule fibrosis and capsule contraction seem more pronounced in eyes with plate-haptic silicone IOLs.18 –20 The incidence of postoperative anterior capsule contraction is probably higher in children than in older patients. This complication did not occur in our study. Masket21 found IOL decentration when loss of loop-shape memory occurred with polypropylene loops. Blotnick et al.22 found distorted and compressed polypropylene loops, resulting in decentration of 3-piece silicone IOLs. We implanted silicone IOLs with a polypropylene haptic in 4 eyes. Optimal IOL support and centration were maintained during the entire follow-up. In our patients, care was taken to maintain the 92
circular shape of the mechanized anterior capsulectomy to reduce the risk of postoperative IOL decentration. Plate-haptic silicone IOLs have been reported to dislocate into the vitreous after posterior capsulotomy.23 However, to our knowledge, this complication has not been associated with 3-piece silicone IOLs. Several methods have been proposed to keep the optical axis clear in infants and young children.10 –14 In our series, the optical axis remained clear in all eyes that had primary posterior capsulectomy and elective anterior vitrectomy during initial surgery. In contrast, all eyes in which the posterior capsule was left intact developed PCO during the follow-up. A higher incidence of postoperative inflammation and opacification of the optical axis has been reported after pediatric cataract surgery.24 –28 Foldable IOLs enable implantation through a smaller incision, possibly reducing intraoperative trauma, postoperative astigmatism, and postoperative inflammatory reaction. In our clinical experience, clear corneal incisions appear to be appropriate for pediatric cataract surgery. Because the incision is performed in avascular tissue, postoperative inflammatory reaction is minimal.29,30 The low postoperative inflammation in our patients was presumably influenced by both the small wound and the clear corneal incision. It has been reported that inflammatory reaction is less after phacoemulsification using the small incision technique.31–33 We believe that the functional outcome in our series could have been considerably better. The possible cause of a poor postoperative visual outcome was deprivation amblyopia. Severe deprivation amblyopia was thought to be present at the time of referral in 4 eyes. This shows that despite pediatric routine screening, the cataracts were detected too late. Compliance with occlusion therapy was less than desirable in 3 children. At present, PMMA is still the standard IOL optic material in pediatric cataract surgery. There are more recent reports of foldable acrylic IOL implantation in infants and young children8 (D. Stager, “Foldable Acrylic Intraocular Lenses in Children,” presented at the annual meeting of the American Academy of Ophthalmology, San Francisco, California, USA, October 1997; M.E. Wilson, D.R. Holland, “In-the Bag Secondary Intraocular Lens Implantation in Children,” presented at the Symposium on Cataract, IOL and Refractive Surgery, San Diego, California, USA, April 1998).
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Both silicone and acrylic IOLs allow implantation through a small incision. Acrylic IOLs are associated with a lower PCO rate than silicone or PMMA lenses.34 The truncated edge of the acrylic IOLs is thought to be responsible for this. The barrier effect of the square optic edge, in addition to the material itself, may inhibit lens epithelial cell migration over the visual axis. The future will show whether new silicone IOLs with square-edged optics will result in less PCO and thus lower Nd:YAG rates. In infants and young uncooperative children, it is important to prolong the development of visually significant PCO to an age when an Nd:YAG capsulotomy can be performed. If the future IOL design and materials prevent PCO or extend the latent period to the age when the child is cooperative, all currently used surgical methods to prevent postoperative opacification of the optical axis would become superfluous. Until then, in our clinical experience, the central posterior capsulectomy and anterior vitrectomy should be performed during the cataract surgery in every uncooperative child. Besides postoperative anatomic IOL stability, important prerequisites in pediatric cataract surgery are that the IOL’s refractive power and clarity are retained and that the IOL material remains biologically inert during the long life-span after cataract removal in pediatric cases. As an IOL material, PMMA has a track record of biocompatibility of almost 50 years. Compared with the life expectation after cataract removal in children, even this period of observation is relatively short to make conclusions about the material’s biocompatibility and stability. Clinical experience with silicone IOLs is much shorter than with PMMA IOLs. We were unable to find previous reports of silicone IOL implantation in infants and small children in the literature. Laboratory data suggest that silicone has the appropriate chemical, optical, and mechanical properties for use as an IOL.35 Clinical experience of cataract surgery in adults confirms this.36 –39 Experimental data show that silicone is resistant to hydrolytic and ultraviolet degradation over a simulated 20 years in the eye.35 Silicone seems to possess at least the same biological interactions as PMMA as measured by cell adhesion in vitro and in vivo.40 – 43 A study of the modulation transfer function showed that the optical performance of silicone IOLs was not as good as that of PMMA IOLs and
that contrast acuity was slightly better with PMMA IOLs.38 Regarding the long life expectancy after cataract removal in children, slightly less contrast and a less sharp image in the macula must not be considered disadvantageous. The IOL need not produce a retinal image that is superior to that of the natural crystalline lens. One report found that eyes with a PMMA IOL were twice as likely to develop worsening of age-related macular degeneration than eyes with silicone IOLs (M. Paul, “The Effects of Silicone Versus PMMA IOLs on Macular Degeneration,” presented at the Symposium on Cataract, IOL and Refractive Surgery, San Diego, California, USA, April 1998). Silicone IOLs have been in use for only about 15 years. We are aware that our small number of cases and short follow-up cannot answer questions about stability and long-term biocompatibility of silicone IOLs in a child’s eye. Our preliminary results suggest, however, that silicone IOL implantation in children is a safe procedure with good and stable short-term anatomic results. Longer follow-up will be necessary to answer questions about the long-term safety of silicone IOLs in children’s eyes.
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of the biocompatibility and fixation of a new silicone intraocular lens in the feline model. J Cataract Refract Surg 1989; 15:545–553 42. Fogle JA, Blaydes JE, Fritz KJ, et al. Clinicopathologic observations of a silicone posterior chamber lens in a primate model. J Cataract Refract Surg 1986; 12:281– 284 43. Yamanaka A, Kazusa R, Takayama S. Cells on the various kinds of intraocular lens implants. Eur J Implant Refract Surg 1989; 1:15–17
From the Department of Ophthalmology, Justus-Liebig-University, Giessen, Germany. Presented in part at the Symposium on Cataract, IOL and Refractive Surgery, San Diego, California, USA, April 1998. None of the authors has a financial or proprietary interest in any product or company mentioned.
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C
ataract extraction with primary intraocular lens (IOL) implantation in children has became more popular in the past decade but still remains a challenge for many ophthalmic surgeons.1 The functional result after pediatric cataract surgery depends not only on the anatomic success of the operation and postoperative maintenance of a clear optical axis but even more on aphakic visual rehabilitation. Conventionally, optical correction is achieved by spectacles or contact lenses.2,3
Accepted for publication September 21, 1999. Reprint requests to Sima Pavlovic, MD, Department of Ophthalmology, Friedrichstrasse 18, 35392 Giessen, Germany. © 2000 ASCRS and ESCRS Published by Elsevier Science Inc.
The success of both relies significantly on parental compliance and the child’s acceptance.2–5 Intraocular lens implantation is theoretically superior to spectacle and contact lens use because it provides almost immediate optical correction that is significantly more reliable because it does not depend on parent or child compliance. Still, there are many controversies about IOL implantation in infants and young children, including IOL size,6 material,6,7 and power calculation8,9; prevention and management of the after cataract10 –14; and the long-term safety of IOLs in the child’s eye. In most reported pediatric cataract cases, poly(methyl methacrylate) (PMMA) IOLs were implanted. 0886-3350/00/$–see front matter PII S0886-3350(99)00333-8
SILICONE IOL IMPLANTATION IN CHILDREN
To our knowledge, primary silicone IOL implantation in infants and young children has not been reported. In 1992, we began primary implantation of silicone IOLs in selected cases of pediatric cataract. We analyzed these cases retrospectively to evaluate postoperative anatomic and functional results as well as complication rates.
Patients and Methods Between 1992 and 1997, cataract extraction and primary silicone IOL implantation were performed in 8 eyes (7 patients) with pediatric cataract. Preoperatively, a detailed history was taken including duration of ocular complaints and birth and family data. Other information obtained was age, sex, visual acuity with or without correction (when possible), slitlamp examination, indirect ophthalmoscopy, presence of squint, and ocular fixation. In older cooperative children, keratometry, intraocular pressure, and axial length measurements were performed in both eyes preoperatively. In younger uncooperative children, IOL power was calculated echographically after keratometry and a thorough examination under an operating microscope. In addition, applanation tonometry and indirect ophthalmoscopy were performed using general endotracheal anesthesia. Keratometry was obtained using the portable handheld auto keratometer, autorefractometer (Retinomax-Plus, Nikon), or both. The type of cataract extraction, intraoperative complications, and all surgical procedures were noted, including IOL style and haptic location as well as management of the posterior capsule and vitreous. Information on the best corrected visual acuity (BCVA) (when possible), refractive error, ocular fixation, and ophthalmic findings with slitlamp, tonometry, and indirect ophthalmoscopy was recorded at postoperative examinations. Recognition visual acuity was determined using optotypes. If the determination of recognition visual acuity was impossible because of poor cooperation, resolution acuity was assessed using the Teller acuity card tests (preferential looking). In younger uncooperative children, at least 1 examination using general endotracheal anesthesia was performed postoperatively under the operating microscope, including applanation tonometry, indirect ophthalmoscopy in mydriasis, and refraction of both eyes by retinoscopy, the portable handheld autorefractometer, or both. Other postopera-
tive data included duration of follow-up, reasons for poor BCVA, and subsequent postoperative procedures (e.g., capsulotomy, suture removal). Preoperatively, pupils were dilated with phenylephrine hydrochloride 5%, cyclopentolate hydrochloride 1%, tropicamide 0.5%, and flurbiprofen sodium 0.03% eyedrops. All children had surgery under general endotracheal anesthesia. Detailed informed consent was obtained from each child’s parents after they had been fully informed about the nature and risks of the procedure; the unknown long-term risks associated with silicone IOL implantation in children were emphasized. In all cases, the opaque lens was removed through 2 paracenteses, followed by IOL implantation through a 3.5 mm clear corneal incision at the superior limbus. Two paracenteses were made with a stiletto knife at 10 and 2 o’clock. If the pupil was not sufficiently dilated, 0.5 cc of preservative-free epinephrine 1:10000 was injected into the anterior chamber. The anterior chamber was filled with a highly viscous viscoelastic substance (Healon GV威). A vitrector with side-port cutting capability and a diameter of 0.6 mm was used to perform a nearly circular anterior capsulectomy in 6 cases. Irrigation was provided by the irrigation device through the second paracentesis. Continuous curvilinear capsulorhexis (CCC) was performed using a cystotome needle in 2 eyes. After anterior capsulectomy, the lens nucleus was removed using the vitrector, combining aspiration and cutting. The residual cortex was removed through the 2 paracenteses using the bimanual irrigation/aspiration (I/A) device. After the anterior chamber was refilled with viscoelastic substance, a 3.5 mm wide and 1.5 to 2.0 mm long 3-step clear corneal incision was made at the superior limbus. A silicone IOL was folded and implanted under viscoelastic material through the clear corneal tunnel. The IOL was inserted with the leading haptic followed by rotating the trailing haptic into the capsular bag. In all cases, a 3-piece biconvex silicone IOL with a 6.0 mm optic and 13.0 mm overall length was used. In 4 eyes, an IOL with PMMA loops was implanted (SI40NB, Allergan Medical Optics) and in 4 eyes, an IOL with polypropylene loops (SI-30NB, Allergan Medical Optics). The corneal incision was sutured with interrupted 10-0 monofilament nylon sutures in 5 eyes or a 10-0 polyglactin suture (Vicryl威) in 3 eyes.
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After IOL implantation, primary central posterior capsulectomy and shallow anterior vitrectomy were performed bimanually in 4 patients by introducing the vitrector through 1 paracentesis behind the IOL optic. Irrigation was provided by the irrigation device through a second paracentesis. The viscoelastic material was then completely removed from the anterior chamber with a bimanual I/A device. The pupil was constricted with intracameral carbachol 0.01%. The paracenteses were closed by hydrotamponade. If either paracentesis was leaking, an additional interrupted 10-0 suture was placed at this site to ensure a watertight wound. All patients received broad-spectrum antibiotics intravenously at the time of surgery. Subconjunctival gentamicin sulfate (10 mg) and dexamethasone sodium phosphate (2 mg) were administered at the end of the surgery. Postoperatively, the eyes were treated with topical dexamethasone 0.1% and neomycin sulfate 0.5% 6 times daily and flurbiprofen 4 times daily. Patching for amblyopia was instituted when indicated, depending on the fixation preference, visual acuity, or both.
Results At the time of surgery, mean patient age was 5.1 years (range 8 months to 15 years). The timing of the cataract extraction was primarily determined by the patient’s referral to the clinic. All but 1 child were older than 1 year at presentation. Most patients presented without adequate records of previous examinations; in many cases it was not possible to establish the age of cataract onset with certainty. Mean follow-up was 29.6 months (range 18 and 46 months). Patient demographics are shown in Table 1. Morphologically, nuclear cataract was most common. In 4 of 7 patients, the cataract was bilateral (Table 2). In 1 patient, a persistent hyaloid artery was present. Three patients had strabismus preoperatively. In 1 patient, a silicone IOL was implanted bilaterally. In 3 other patients with bilateral cataract, a single-piece PMMA IOL was implanted in the fellow eye. The targeted postoperative refraction was ⫹3.00 diopters (D) in children younger than 2 years, ⫹2.00 D in children between 2 and 4 years, and emmetropia in children older than 5 years. Table 3 shows the functional 90
Table 1. Patient demographics.
Sex
Age (Years)
Follow-up (Months)
1
F
8.5
46
2
M
2.0
34
3
M
3.4
32
4
M
4.7
35
5
M
0.7
18
6
M
1.4
33
7
F
15.0
20
8
F
15.0
19
Case
Table 2. Types of cataract.
Case
Cataract Type
Cataract Presence
1
Total
Unilateral
Clear lens
2
Total
Bilateral
PMMA IOL
3
Nuclear
Bilateral
PMMA IOL
4
Nuclear
Bilateral
PMMA IOL
5
Nuclear
Unilateral
Clear lens
6
Nuclear⫹P.Lent⫹PHA
Unilateral
Clear lens
7
Nuclear
Bilateral
Silicone IOL
8
Nuclear
Bilateral
Silicone IOL
Fellow Eye
P.Lent ⫽ posterior lentiglobus; PHA ⫽ persistent hyaloid artery; IOL ⫽ intraocular lens
outcomes and the predicted and obtained postoperative refractions. Postoperative best spectacle-corrected visual acuity ranged from 20/800 to 20/20. Postoperative visual acuity could not be assessed in 1 child with trisomy 21 because of mental retardation. Visual acuity improvement after cataract extraction depended on the type of cataract (bilateral or unilateral) and timing of the cataract surgery. Visual acuity was worse in children with unilateral congenital cataract. Three patients had severe amblyopia in the operated eye (visual acuity 20/200 or less), diagnosed on the basis of a poor fixation pattern in the presence of clear media and evident normal anterior and posterior segments. In all 3 patients, the cataract was unilateral and surgery was performed after they were 8 months old (range 8 months to 8.5 years). Deprivation amblyopia was thought to be present before surgery in 4 eyes. For 5 eyes, occlusion therapy was prescribed post-
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Table 3. Postoperative acuities and refractions. Postoperative BSCVA
Refraction (SE) (D)
Case
Preoperative BSCVA
Operated Eye
Fellow Eye
Operated Eye
Fellow Eye
1
HM
20/800
1.2
⫺0.25
⫹0.90
2
NP
NP
NP
⫹1.50
⫹2.00
3
20/400
20/50
20/32
⫹3.00
⫹1.75
4
20/200
20/63
20/200
⫹0.50
⫺2.00
5
NP
20/200
20/50
⫹2.00
⫹0.50
6
NP
20/800
20/20
⫺0.75
⫹0.25
7
0.3
20/25
—
⫺1.00
—
8
0.3
20/20
—
⫺0.50
—
BSCVA ⫽ best spectacle-corrected visual acuity; HM ⫽ hand movements; NP ⫽ not possible; SE ⫽ spherical equivalent
operatively; of these, 2 showed good compliance based on parental reporting. In all patients, cataract surgery and IOL implantation were uneventful. All IOLs were implanted in the capsular bag. Postoperative inflammatory reaction was minimal. Neither fibrinoid exudation nor posterior synechias were seen postoperatively. All IOLs were well centered and remained anatomically stable during the follow-up. No pigment or cell deposits were seen on the IOL surface. All 4 eyes with an intact posterior capsule developed functionally significant posterior capsule opacification (PCO). Surgical capsulotomy with anterior vitrectomy was performed using general anesthesia in 2 cases because the children did not cooperate during an attempt to perform a neodymium:YAG (Nd:YAG) laser capsulotomy. An Nd:YAG capsulotomy was performed in 2 eyes. Mean time between cataract surgery and capsulotomy in eyes with a silicone IOL was 10.25 months (range 7 to 15 months). One of the 3 fellow eyes with PMMA IOLs required surgical capsulotomy and anterior vitrectomy because of PCO that developed 13 months after cataract surgery. (The fellow eye with a silicone IOL developed PCO after 15 months.) In 2 other fellow eyes with a PMMA IOL, primary posterior capsulotomy and anterior vitrectomy were performed during cataract surgery. These 2 eyes did not develop PCO. One eye with a PMMA IOL developed postoperative pigment deposits on the IOL surface and tiny posterior synechias on the anterior capsule. The remaining 3 fellow eyes with a PMMA IOL did not have postoperative complications.
In all 4 eyes with a silicone IOL that had primary posterior capsulectomy and elective anterior vitrectomy during cataract surgery, the visual axis remained clear during the follow-up. The IOLs remained well centered despite the large posterior capsule opening in all patients. In 1 patient, squint surgery was performed 15 months after cataract surgery. In 4 eyes, the corneal suture was removed (in 2 children using general anesthesia and in 2 at the slitlamp using topical anesthesia). No eye developed glaucoma postoperatively. In 4 uncooperative children at least 1 examination, including applanation tonometry and indirect ophthalmoscopy, was performed postoperatively using general anesthesia. No eye developed corneal or macular edema, hyphema, or retinal detachment.
Discussion Cataract surgery and IOL implantation in infants and young children have improved over the past few decades. However, the elasticity of the sclera and the small eye of the child make cataract extraction significantly more difficult than in adults. Surgery is frequently accompanied by vitreous pressure and a shallow anterior chamber, which increase trauma to the iris and corneal endothelium and cause a more pronounced postoperative inflammatory reaction. In the current study, these problems were solved by removing the opaque lens through 2 paracenteses using bimanual I/A or irrigation/vitrectomy, as well as implanting a foldable IOL through a 3.5 mm corneal incision. Filling the anterior chamber with a highly viscous
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viscoelastic material counteracts the vitreal pressure and facilitates instrument and IOL insertion in the anterior chamber. The viscoelastic substance remains in the anterior chamber during the entire procedure. Bimanual I/A kept the anterior chamber formed and reduced the instruments’ contact with the corneal endothelium and the iris. The capsule’s extreme elasticity, increased intravitreal pressure, and small eye in infants and young children make manual CCC difficult. The leading edge of the CCC tends to extend outward, and capsulotomy size is difficult to control. Mechanized capsulectomy using bimanual irrigation/vitrectomy results in smooth, slightly scalloped capsulectomy edges that are not sharp or broken.15 As shown by Wilson and coauthors15,16 and Wang et al.,17the method of anterior capsulectomy used in our study does not cause radial tears, which can also be avoided by maintaining a circular capsulectomy. According to our clinical experience, this anterior capsulectomy configuration is stable during subsequent foldable IOL implantation. In our series, no radial tears developed intraoperatively. Performing anterior capsulotomy and lens removal in the closed eye through the 2 paracenteses controlled vitreal pressure and maintained a deep anterior chamber throughout surgery in all 7 patients. All eyes had a low postoperative inflammatory reaction and a clinically well-centered IOL. We believe this is not directly the result of the silicone IOL but rather of the small incision cataract surgery. In infants and young children, we recommend using a suture even with a small tunnel incision. We advise using a 10-0 polyglactin suture in small uncooperative children, eliminating the need for later suture removal. Anterior capsule fibrosis and capsule contraction seem more pronounced in eyes with plate-haptic silicone IOLs.18 –20 The incidence of postoperative anterior capsule contraction is probably higher in children than in older patients. This complication did not occur in our study. Masket21 found IOL decentration when loss of loop-shape memory occurred with polypropylene loops. Blotnick et al.22 found distorted and compressed polypropylene loops, resulting in decentration of 3-piece silicone IOLs. We implanted silicone IOLs with a polypropylene haptic in 4 eyes. Optimal IOL support and centration were maintained during the entire follow-up. In our patients, care was taken to maintain the 92
circular shape of the mechanized anterior capsulectomy to reduce the risk of postoperative IOL decentration. Plate-haptic silicone IOLs have been reported to dislocate into the vitreous after posterior capsulotomy.23 However, to our knowledge, this complication has not been associated with 3-piece silicone IOLs. Several methods have been proposed to keep the optical axis clear in infants and young children.10 –14 In our series, the optical axis remained clear in all eyes that had primary posterior capsulectomy and elective anterior vitrectomy during initial surgery. In contrast, all eyes in which the posterior capsule was left intact developed PCO during the follow-up. A higher incidence of postoperative inflammation and opacification of the optical axis has been reported after pediatric cataract surgery.24 –28 Foldable IOLs enable implantation through a smaller incision, possibly reducing intraoperative trauma, postoperative astigmatism, and postoperative inflammatory reaction. In our clinical experience, clear corneal incisions appear to be appropriate for pediatric cataract surgery. Because the incision is performed in avascular tissue, postoperative inflammatory reaction is minimal.29,30 The low postoperative inflammation in our patients was presumably influenced by both the small wound and the clear corneal incision. It has been reported that inflammatory reaction is less after phacoemulsification using the small incision technique.31–33 We believe that the functional outcome in our series could have been considerably better. The possible cause of a poor postoperative visual outcome was deprivation amblyopia. Severe deprivation amblyopia was thought to be present at the time of referral in 4 eyes. This shows that despite pediatric routine screening, the cataracts were detected too late. Compliance with occlusion therapy was less than desirable in 3 children. At present, PMMA is still the standard IOL optic material in pediatric cataract surgery. There are more recent reports of foldable acrylic IOL implantation in infants and young children8 (D. Stager, “Foldable Acrylic Intraocular Lenses in Children,” presented at the annual meeting of the American Academy of Ophthalmology, San Francisco, California, USA, October 1997; M.E. Wilson, D.R. Holland, “In-the Bag Secondary Intraocular Lens Implantation in Children,” presented at the Symposium on Cataract, IOL and Refractive Surgery, San Diego, California, USA, April 1998).
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Both silicone and acrylic IOLs allow implantation through a small incision. Acrylic IOLs are associated with a lower PCO rate than silicone or PMMA lenses.34 The truncated edge of the acrylic IOLs is thought to be responsible for this. The barrier effect of the square optic edge, in addition to the material itself, may inhibit lens epithelial cell migration over the visual axis. The future will show whether new silicone IOLs with square-edged optics will result in less PCO and thus lower Nd:YAG rates. In infants and young uncooperative children, it is important to prolong the development of visually significant PCO to an age when an Nd:YAG capsulotomy can be performed. If the future IOL design and materials prevent PCO or extend the latent period to the age when the child is cooperative, all currently used surgical methods to prevent postoperative opacification of the optical axis would become superfluous. Until then, in our clinical experience, the central posterior capsulectomy and anterior vitrectomy should be performed during the cataract surgery in every uncooperative child. Besides postoperative anatomic IOL stability, important prerequisites in pediatric cataract surgery are that the IOL’s refractive power and clarity are retained and that the IOL material remains biologically inert during the long life-span after cataract removal in pediatric cases. As an IOL material, PMMA has a track record of biocompatibility of almost 50 years. Compared with the life expectation after cataract removal in children, even this period of observation is relatively short to make conclusions about the material’s biocompatibility and stability. Clinical experience with silicone IOLs is much shorter than with PMMA IOLs. We were unable to find previous reports of silicone IOL implantation in infants and small children in the literature. Laboratory data suggest that silicone has the appropriate chemical, optical, and mechanical properties for use as an IOL.35 Clinical experience of cataract surgery in adults confirms this.36 –39 Experimental data show that silicone is resistant to hydrolytic and ultraviolet degradation over a simulated 20 years in the eye.35 Silicone seems to possess at least the same biological interactions as PMMA as measured by cell adhesion in vitro and in vivo.40 – 43 A study of the modulation transfer function showed that the optical performance of silicone IOLs was not as good as that of PMMA IOLs and
that contrast acuity was slightly better with PMMA IOLs.38 Regarding the long life expectancy after cataract removal in children, slightly less contrast and a less sharp image in the macula must not be considered disadvantageous. The IOL need not produce a retinal image that is superior to that of the natural crystalline lens. One report found that eyes with a PMMA IOL were twice as likely to develop worsening of age-related macular degeneration than eyes with silicone IOLs (M. Paul, “The Effects of Silicone Versus PMMA IOLs on Macular Degeneration,” presented at the Symposium on Cataract, IOL and Refractive Surgery, San Diego, California, USA, April 1998). Silicone IOLs have been in use for only about 15 years. We are aware that our small number of cases and short follow-up cannot answer questions about stability and long-term biocompatibility of silicone IOLs in a child’s eye. Our preliminary results suggest, however, that silicone IOL implantation in children is a safe procedure with good and stable short-term anatomic results. Longer follow-up will be necessary to answer questions about the long-term safety of silicone IOLs in children’s eyes.
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of the biocompatibility and fixation of a new silicone intraocular lens in the feline model. J Cataract Refract Surg 1989; 15:545–553 42. Fogle JA, Blaydes JE, Fritz KJ, et al. Clinicopathologic observations of a silicone posterior chamber lens in a primate model. J Cataract Refract Surg 1986; 12:281– 284 43. Yamanaka A, Kazusa R, Takayama S. Cells on the various kinds of intraocular lens implants. Eur J Implant Refract Surg 1989; 1:15–17
From the Department of Ophthalmology, Justus-Liebig-University, Giessen, Germany. Presented in part at the Symposium on Cataract, IOL and Refractive Surgery, San Diego, California, USA, April 1998. None of the authors has a financial or proprietary interest in any product or company mentioned.
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