Pediatric Cataract Management with Variations in Surgical Technique and Aphakic Optical Correction

Pediatric Cataract Management with Variations in Surgical Technique and Aphakic Optical Correction fohn R. Ainsworth, FRCS, FRCOphth/ Sandi Cohen,2 Alex V. Levin, MD, FRCSC,2 David S. Rootman, MD, FRCSC2 Purpose: The purpose of the study was to compare the results of three techniques of cataract surgery in children. Two methods included intraocular lens (IOL) implantation and one used contact lens correction of aphakia. Design: Nonrandomized clinical trial. Participants: Seventy-seven eyes of 50 children between the ages of 2 %and 16 years who had cataract surgery for the treatment of uncomplicated cataract. Intervention: Thirty-one eyes underwent a "conventional" style of implantation, and a "phaco-style" of surgery was used in 24 eyes. A contact lens was used as the primary means of aphakic correction in 22 eyes. Main Outcome Measures: The visual results and complications of each type of surgery were compared. Results: Corrected visual acuities did not differ significantly between the three groups 6 months after surgery. The incidence and type of complications were significantly different. Better lens centration, less long-term iris changes, or wound-related problems were observed with "phaco-style" modification of the technique of IOL insertion. Conclusions: Pediatric IOL insertion eliminated the need for contact lens wear and did not lead to a significantly different corrected visual acuity 6 months after surgery compared with lensectomy with contact lens correction. Adoption of some of the techniques of modern small-incision cataract surgery for pediatric IOL procedures produces a significant reduction in postoperative anterior segment complications compared with a standard limbal approach. Such modifications allow pediatric IOL insertion to be a safe alternative for the correction of pediatric aphakia. Ophthalmology 1997; 104:1096-1101

Cataract removal in children poses unique operative and postoperative challenges. A satisfactory success rate has been reported 1,2 using the standard technique of lensectomy, primary posterior capsulotomy, anterior vitrecOriginally received: March 6, 1996. Revision accepted: March 3, 1997, 1 Birmingham Children's Hospital, Birmingham, England, 2 Department of Ophthalmology, The Hospital for Sick Children, University of Toronto, Toronto, Canada.

The authors have no financial interest in any product mentioned in the article, Reprint requests to John R. Ainsworth, FRCS, FRCOphth, Department of Ophthalmology, Birmingham Children's Hospital, Ladywood Middleway, Birmingham, Bl6 8ET, England,

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tomy, and subsequent contact lens wear, although practical and theoretical concerns in relation to effects on the posterior segment and contact lens usage remain. 3 ,4 Intraocular lens (IOL) use in children has increased over the past 20 years. Uncertainty of long-term biocompatibility slowed the spread of IOL implantation in children,s but the development of improved materials, design, and insertion technique6 ,7 has led to greater acceptance. Initial use had been limited largely to unilateral and traumatic cataracts, with variable success. 8 ,9 More recently, excellent visual results have been reported in which posterior chamber intraocular lenses (PCIOLs) have been implanted in children older than 2 to 3 years of age undergoing surgery7,10,11 for nontraumatic bilateral cataracts. It is not yet clear whether primary PCIOL implantation

Ainsworth et al . Techniques of Pediatric Cataract Surgery Table 1. putcome Data Surgery type Surgery details

Number of eyes Number of patients Mean age at surgery (yrs) Standard deviation (yrs) Mean logMAR best visual acuity 6 mos after surgery (Snellen) Standard deviation (Snellen) Number (%) of eyes with complications Number (%) of eyes requiring reoperation

Group A

Group B

Group C

Lensectomy/vitrectomy Lensectomy Posterior capsulotomy Anterior vitrectomy Gas-permeable contact lens

Extracapsular Limbal incision Can opener capsulotomy Lensectomy PClOL insertion 31 19 9.1 4.0 0.20 (20/32)

Phaco-style Tunnel incision Capsulorrhexis Endocapsular PCIOL

22 15 7.5

3.2 0.21 (20/32)

0.16 9 (40) 5 (23)

0.17 12 (39) 8 (26)

24

16

8.8

4.8

0.18 (20/30)

0.12 3 (13) o (0)

perOL = posterior chamber intraocular lens.

or lensectomy with contact lens rehabilitation has the least risk of complication or produces the best visual function. Although results of particular surgical techniques have been published,I ,6.7,12 no study has attempted to compare the results of these different surgical approaches. The high surgical workload and former variation in technique undertaken at The Hospital for Sick Children in Toronto has made possible a comparative study of three methods of pediatric cataract management.

Patients and Methods All patients undergoing cataract surgery between January 1990 and December 1994 were identified retrospectively from operating room data at The Hospital for Sick Children, Toronto. Eyes with preoperative contraindication to PCIOL implantation (crystalline lens subluxation, iritis, previous intraocular surgery) were not included in any of the three study groups. We identified 208 eyes of 164 children between 2 1/2 and 16 years of age eligible for IOL implantation who had undergone cataract surgery with a minimum of 6 months postoperative review. Further exclusion of patients with confounding factors affecting vision (perforating injury, unilateral congenital cataract, the worse eye of asymmetric cataract, developmental delay precluding recognition acuity testing) left a group of 77 eyes of 50 patients, the cataracts of which were predominantly either congenital, requiring removal due to progression or increasing visual requirements, or developmental in nature. Forty-four patients had bilateral cataracts. In 17 patients, 1 eye only was included, as the fellow eye had a greater degree of cataract or underwent surgery outside of the study period or at a different hospital. The six patients with unilateral cataract were at least 6 years old with a mean age of 9.6 years and had lens opacities of relatively recent onset. The 77 cases were divided into 3 groups on the basis of type of surgery performed (Table 1). Surgery was performed by one staff ophthalmologist in group B and a

different staff ophthalmologist in group C, both of whom used their preferred approach. Operations in group A were undertaken by one of three surgeons, using a technique they were using regularly on children of a younger age than those in the study. The surgical technique depended on which ophthalmologist was managing the case, subject to informed parental consent, rather than differences in the type of cataract or patient characteristics. The median preoperative acuities for the three groups were not significantly different (group A =: 0.9 log of the minimum angle of resolution [logMAR), group B = 1.0 10gMAR, group C =: 1.0 logMAR). Surgical Techniques Group A: Lensectomy-Vitrectomy with Contact Lens Rehabilitation

22 Cases. A smalilimbalconjunctival peritomy incision was created, and the anterior chamber was entered at the surgical limbus via a 3.2-mm wound. A small stab incision was created in the superior one third of the anterior capsule and the anterior chamber filled with viscoelastic (Healon; Pharmacia, Uppsala, Sweden). An endocapsular aspiration of lens material followed by widening of the anterior capsu10tomy, posterior capsulotomy, and limited anterior vitrectomy were performed with a DAISY digital irrigation-aspiration system with cutter fitted with an irrigation sleeve (Storz, St. Louis, MO), A 2- to 3mm rim of peripheral anterior and posterior capsule was retained. The wound was cleared of any vitreous strands, if present, and was closed with two 8-0 Vicryl sutures (Ethicon, Peterborough, Ontario). A rigid gas-permeable contact lens was fitted 1 to 2 weeks after surgery. General anesthesia was used, if necessary, to allow keratometry, fitting of contact lens, and overrefraction. Group B: Extracapsular Extraction with Intraocular Lens 31 Cases. Preoperative biometry and keratometry were obtained in all cases, either in the office or with the patient under anesthesia immediately before commence-

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ment of cataract surgery. The IOL powers were calculated using axial length and keratometry using the SRKI formula. Lens power was selected to achieve emmetropia. A Fleiringa ring was sutured to the globe in some instances to provide scleral support. A conjunctival peritomy incision was created, and a partial-depth 6.5-mm incision was made at the limbus. The anterior chamber was entered at the limbus via a 3.2-mm wound, the anterior chamber was filled with viscoelastic (Healon), and a "can opener" anterior capsulotomy was performed with a 25-gauge bent-needle cystotome. Lens material was aspirated with either the DAISY automated aspiration-irrigation instrument with irrigation sleeve (Storz) or a manual Simcoe double-barreled irrigation-aspiration cannula. The limbal wound was enlarged to 6.5 to 7 mm, and a 6.5-mm optic polymethylmethacrylate one-piece intraocular lens (sp24ub or sp13ub; Intraoptics, Chiron, Richmond Hill, Ontario) was inserted under viscoelastic (Heal on) into the ciliary sulcus. The limbal wound was closed with interrupted lO-O nylon sutures after viscoelastic removal. Group C: "Phaco-style" Surgery 24 Cases. Preoperative biometry and keratometry were obtained as in group B. A small fornix-based conjunctival flap was created, and a linear 6.5-mm wide 2mm long scleral tunnel extending into cornea was created with a crescent blade. The anterior chamber was entered with a 2.8-mm keratome followed by a paracentesis displaced 60° from the principal incision. Anterior continuous curvilinear capsulorrhexis (CCC) was performed with forceps under viscoelastic (Healon). The lens was aspirated with manual irrigation-aspiration technique using a Simcoe cannula. The wound then was enlarged to 6.5 mm while preserving a tunnel configuration, and a bimanual technique was used to insert a 6.5-mm optic single piece polymethylmethacrylate intraocular lens (sp24ub or sp13ub; Intraoptics) into the capsular bag. Viscoelastic was replaced with balanced salt solution (Alcon, Ft. Worth, TX), and the scleral wound was closed with a continuous 10-0 nylon suture. Patients of all three groups used eye protection after surgery and received topical antibiotic for 2 weeks and topical steroid and atropine for 6 weeks after surgery. Topical steroids were prescribed hourly for 1 to 2 weeks. Best-corrected visual acuity and anterior segment findings at 6 months after surgery were used for comparison. A list of intraoperative events and postoperative complications was drawn up before data acquisition, and instances of these during surgery or the first 6 months after surgery were recorded. Adverse intraoperative events included inadvertent posterior capsule tear or vitreous loss, loss of lens material into vitreous space, and vitreous hemorrhage persisting more than 1 month. The following were recorded as postoperative complications: IOL subluxation, capsular opacification not possible to treat with YAG laser, posterior synechia, IOL-pupil capture, persisting astigmatism of greater than 3 diopters not present before surgery, iritis persisting for more than 2 months after surgery, endophthalmitis, vitreous hemorrhage, iris prolapse, precipitates on IOL, and vitreous strands extending to incision. Reoperations during the 6-month

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postoperative period were recorded. Anesthesia to allow contact lens fitting was not regarded as a reoperation. Data were entered into an Excel spreadsheet (Microsoft, Seattle, W A). Mean 10gMAR values for best-corrected linear visual acuity in each group were calculated and compared using Student's t test for unpaired data. The number of eyes suffering intraoperative or postoperative complications and the number requiring reoperation were compared among the three groups using a chi-square (X 2 ) test.

Results Mean 10gMAR visual acuity, incidence of complications, and number of secondary operations were calculated for each group (Table 1). Mean best-corrected visual acuity 6 months after cataract removal did not differ significantly among the groups, with mean linear Snellen acuities of approximately 20/30 (logMAR 0.20) in all three. Regression analysis of each group suggested there was no significant relation within the parameters of the study between age at surgery and best visual acuity at 6 months after surgery. Group B showed a trend toward a lower acuity in children undergoing surgery at an early age. Table 2 details the complications encountered in each group. The X2 testing results showed significantly more complications encountered in group B compared to those of group C (X 2 = 4.33, 0.05 > P > 0.02), and fewer reoperations in group C than those of group A (X 2 = 5.88, 0.02 > p > 0.01) or B (X 2 = 6.97, 0.01 > P > 0.001). Group A eyes most commonly developed a permanent intolerance of contact lens (18% of cases) or isolated instances of intraoperative and immediate postoperative problems such as macular edema (one case), persisting vitreous hemorrhage (one case), or severe uveitis with hypopyon (one case). The most common complications encountered in group B were posterior synechiae with or without pupil capture (10% of cases), postoperative lens subluxation (3% of cases), and recurrent posterior capsule opacification after neodymium: YAG (Nd: YAG) capsulotomy. In group C, there was one case of posterior synechia with pupil capture (4%), a case of suspected endophthalmitis (4%), and precipitates on one IOL (4%). Failure of compliance with contact lens wear, despite the support of a highly experienced contact lens clinic staff and trials of different lens types, was the most common reason for reoperation in group A (18% of cases). A secondary PCIOL was inserted in each case. Woundrelated problems such as astigmatism or iris prolapse required reoperation in 13% of cases in group B. No reoperations were required in group C cases.

Discussion Pediatric cataract surgery has inherited techniques and instrumentation that were introduced initially for use in adults. Historically, the greatest advance probably occurred with the adoption of irrigation-aspiration and automated vitrectomy instruments. 3 Subsequently, many

Ainsworth et al . Techniques of Pediatric Cataract Surgery Table 2. Visual Outcome in Eyes with Complications: LogMAR Best-corrected Acuity (Snellen Equivalent) Group A Complication

Number

Mean Acuity

Wound related Astigmatism Iris prolapse Vitreous to wound IOL related Pupil capture Synechia Lens precipitates Subluxation Recurrent capsule opacity Posterior segment related Vitreous loss Vitreous hemorrhage Macular edema Inflammatory Contact lens intolerance

4

0.17 (20/30)

Total

9

0.25 (20/36)

0.48 (20/60)

2

0.36 (20/46) 0.17 (20/30) 0.17 (20/30)

Group B Number

Group C

Mean Acuity

1 2

0.1 (20/25) 0.29 (20/39)

2 1 1 1 1

0.36 0.0 0.17 0.48 0.1

Number

(20/46) (20/20) (20/30) (20/60) (20/25)

Mean Acuity

0.1

(20/25)

0.0 (20/20)

0.0 (20/20) 2

0.0 (20/20)

12

0.18 (20/30)

0.17 (20/30) 3

0.09 (20/25)

IOL = intraocular lens.

variations in technique have developed in different centers. Meanwhile, the management of cataract in the adult population has attained new standards of excellence. 13 We have shown that modem lens extraction in children older than 2 to 3 years of age suffering uncomplicated cataracts can achieve excellent mean visual acuity results that are similar to those obtained in the adult population. In contrast, a high complication rate was found, similar to that reported in all equivalent studies of pediatric cataract management. 7 ,IO.14-20 Their severity was not such as to cause a major reduction in vision within the period of the study. A long-term study would ascertain whether differences in outcome may develop in subsequent years. We have shown that "traditional" lensectomy with contact lens correction leads to a satisfactory visual outcome in children fulfilling the criteria of the current study, with the disadvantage that almost one-fifth of children will fail to tolerate the contact lens and an occasional patient will encounter significant complications. Although it may be the case that infants fitted with contact lenses may have a rebellious period as toddlers in which temporary noncompliance may be tolerated with expectation of a return to lens use, the children in the current study were older and difficulties of compliance and tolerance dated from the first weeks of contact lens use. Implantation of a PCIOL at the time of cataract surgery did not compromise the medium-term visual outcome in our patients. The increased capsular fibrosis and greater iris adhesiveness seen in children,24 along with the type of incision, may have led to the problems encountered in group B. Use of a tunnel incision in group C was crucial in eliminating wound-related complications. Children are prone to accidental or self-inflicted trauma in the postoperative period25 ,26 despite parental instruction and eye protection. A carefully sutured self-sealing tunnel incision

combined with eye shielding would therefore seem appropriate to prevent incidents of wound dehiscence following implantation. The posterior suture placement in group C compared with that of group B prevented astigmatism and suture protrusion, thereby eliminating the need for suture removal, which sometimes must be performed with the patient under general anesthesia. We believe that the use of a tunnel incision produced a deeper anterior chamber during IOL insertion and prevented intraoperative iris prolapse, thus reducing iris trauma and consequent postoperative inflammation. Long-term IOL centration is achieved more consistently in the presence of endocapsular implantation and an intact CCC 27 ,28 as described by Gimbel et a1. 7 No cases of IOL subluxation occurred in group C. Creating a CCC in children is more difficult than in the aging eye29 and requires a modification in technique. 30 An intact CCC was achieved in all cases in group C, showing that the technique can be performed reliably in children older than 21/2 years by a surgeon operating regularly on pediatric cataracts. An attempt was made to create a CCC of approximately 5 mm so that the edge of the IOL optic would be enclosed within the capsular bag. Interestingly, the CCC did not fully cover the optic edge in the patient in group C in whom posterior synechia developed. Accurate haptic placement within the capsular bag was not possible in group B because of the collapsible nature of the child' s eye in the absence of a tunnel incision. 18 - 21 It is possible that implantation may increase the amount of postoperative inflammation,24 although we suspect that use of modern endocapsular-fixated IOLs, avoidance of iris trauma,17 and vigorous use of topical medication6 reduces the risk of severe postoperative uveitis. Nevertheless, control of iritis in the presence of an IOL is essential to prevent potentially serious sequelae. 8,24

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Widely differing regimens of anti-inflammatory and cycloplegic agents have been advocated5,6,31 to avoid the potentially serious consequences of posterior synechia formation,21,24 Centers reporting high rates of this complication may be expected to treat a high proportion of patients with heavily pigmented irides, 16,23,32 It may be possible to reduce iris-lens synechiae and lens precipitates with the use of surface-modified polymethylmethacrylate 17 or hydrogel 25 ,33 lenses. Further research is indicated to ascertain the most effective postoperative therapy, optimal lens type and dimension, and groups at increased risk of complications. No child required anesthesia for Nd: YAG laser capsulotomy, despite a high rate of capsule opacification. Prompt treatment of capsule opacity, contact lens intolerance, and residual refractive error prevented the development of amblyopia in all three groups after surgery. Analysis of cataract extraction outcome in children is more difficult than in adult patients, because pediatric cataracts are uncommon, amblyopia may be present, and accurate best visual acuity can be difficult to obtain. We have sought to minimize these extraneous variables and confounding factors by our selection criteria for recruitment, excluding patients with developmental delay, those with likely pre-existing amblyopia or with other ocular abnormalities. Consequently, we cannot extrapolate our results to surgery undertaken in the first 2 years of life or in which such factors as developmental delay, amblyopia, penetrating trauma or other ocular abnormalities are present before cataract removal. Other studies have explored these areas to some extent. 34-36 It may be argued that the validity of any difference in outcome among the three groups may be compromised by the fact that different ophthalmologists were responsible for each of the three types of operation. However, all were experienced surgeons who were performing their preferred technique. Such an approach may be more relevant than a single surgeon undertaking a variety of surgical approaches, some of which the surgeon may not be using routinely. It would have been difficult to allocate patients randomly to different surgeons and techniques for similar reasons, and we think that the composition of the three groups was sufficiently homogeneous to allow statistical comparison by case-control methodology. We would argue that modification of surgical technique, not surgeon, was the key factor in producing the different outcomes in the three groups. The majority of patients in all three groups have continued to be reviewed after the initial 6 months used for analysis in the current study. Average follow-up interval is now more than 18 months (range, 6-53 months). It is not possible currently to compare outcome data over a longer period than 6 months because of differences in length of follow-up between groups and patients. No new problems have appeared after the initial 6 months, although there has been progression of a minority of the complications observed within the first 6 months after surgery, particularly in group B. Two eyes in group B are likely to require further surgery to remove capsular fibrosis leading to progressive IOL subluxation or recurrent visual pathway opacity. Group C continues to have

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minimal problems after surgery, although recurrent capsular opacification continues to appear; this has led to the performance of primary posterior capsulotomy and anterior vitrectomy in selected cases. The style of surgery performed in group B has ceased since the conclusion of the study with the intention of minimizing postoperative complications. Despite the encouraging initial results now achievable in pediatric lens implantation, the long-term effects of IOL use in this group are not fully known. The most likely source for late visual compromise may prove to originate in some of the minor complications encountered during the patients' initial management, and we advocate surgical modifications to reduce or eliminate these.

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