- Email: [email protected]
Pediatric cataract surgery in Nepal
articles Pediatric cataract surgery in Nepal Jaya Thakur, MD, Harsha Reddy, M. Edward Wilson, Jr, MD, Govind Paudyal, MD, Rita Gurung, MD, Suman Thapa, MD, Geoffrey Tabin, MD, Sanduk Ruit, MD Purpose: To describe the first pediatric cataract surgery case series report from Nepal. Setting: Tilganga Eye Center, Kathmandu, Nepal. Methods: This study comprised a consecutive series of 112 eyes of 85 children having cataract surgery with intraocular lens (IOL) implantation. General anesthesia of ketamine combined with peribulbar block was used in all patients. Patients’ demographics, cataract type and presenting symptoms, surgical intervention, preoperative and postoperative visual acuities, and follow-up clinical examinations were recorded. Results: Seventy-three eyes (65.2%) of 53 patients had extracapsular cataract extraction with posterior capsulotomy, anterior vitrectomy, and posterior chamber IOL implantation (ECCE⫹PCAP⫹AV⫹PCIOL), and 39 eyes (34.8%) of 32 patients had cataract extraction and IOL implantation with an intact posterior capsule (ECCE⫹PCIOL). Of all patients, the mean age at surgery was 6.2 years ⫾ 4.3 (SD). The median age in the ECCE⫹PCAP⫹AV⫹PCIOL group was 4.7 years and in the ECCE⫹PCIOL group, 11.0 years. The mean follow-up was 5.4 ⫾ 5.3 months. The most common postoperative complication in the ECCE⫹PCIOL group was visual axis/posterior capsule opacification, which was seen in 18 eyes (46.2%) compared to 4 eyes (5.5%) in the ECCE⫹PCAP⫹AV⫹PCIOL group. Visual acuity improved with surgery in both groups. The leading cause of poor outcomes was deprivation amblyopia. There were no anesthesia-related complications. Conclusions: Implantation of an IOL at the time of cataract extraction under combined systemic ketamine and peribulbar lidocaine anesthesia appeared to be well tolerated and produced significant visual improvement in pediatric patients in Nepal. Primary posterior capsulotomy and AV helped prevent visual axis opacification without a significant increase in complications. J Cataract Refract Surg 2004; 30:1629–1635 2004 ASCRS and ESCRS
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he World Health Organization’s (WHO) global initiative for the elimination of avoidable blindness by the year 20201 has identified the control of childhood blindness as a priority. Cataract remains one of the most important causes of avoidable blindness in children. Worldwide, an estimated 200 000 children are currently Accepted for publication December 23, 2003. Reprint requests to M. Edward Wilson, Jr, MD, MUSC–Storm Eye Institute, 167 Ashley Avenue, Charleston, South Carolina 29425-5536, USA. E-mail [email protected]. 2004 ASCRS and ESCRS Published by Elsevier Inc.
blind from cataract, and every year 20 000 to 40 000 neonates are born with congenital cataract.2 The burden of illness disproportionately affects the developing world, where the prevalence of cataract blindness is 10 times higher than in developed countries.3 Pediatric cataract takes an enormous toll on developing countries in the form of human morbidity, economic loss, and social burden.4 Many infants with debilitating cataracts do not survive childhood. For those who do, the long-term burden of disability is tremendous. A child who goes blind today is likely to 0886-3350/04/$–see front matter doi:10.1016/j.jcrs.2003.12.047
PEDIATRIC CATARACT SURGERY IN NEPAL
live until 2050.1 Accordingly, restoring this child’s sight may be equivalent to restoring the sight of 10 elderly adults1 in terms of “blind years” avoided, gained productivity, and overall savings to society. In Nepal, as in other developing countries, cataract is believed to be a leading cause of blindness in children. Although no formal data on the prevalence of the disease have been published, many pediatric cataract cases are routinely seen in outpatient hospital settings and screening camps organized by local charities (Tilganga Eye Center Annual Report, 2001–2002, pages 10–13). A dedicated team effort with advanced technological resources is required to manage childhood cataract.4 Because of the lack of advanced technology in many developing countries, surgical outcomes there have traditionally been very poor. In Nepal, a significant barrier to effective cataract surgery has been a lack of equipment, in particular the automated suction-cutting (vitrector) machine. A shortage of trained anesthesiologists and the expense of advanced monitoring equipment have also made it difficult for ophthalmic surgical centers to set up and maintain advanced monitored-anesthesia protocols for children.4 As a result, few ophthalmic procedures are currently done under conventional general anesthesia in Nepal. In addition, implanting intraocular lenses (IOLs) in pediatric eyes has only recently been accepted, even in older children.5 Postoperative refractive change with ocular growth in children presents another challenge. However, the price and maintenance of contact lenses make them impractical for most families in the developing world and aphakic eyeglasses are often lost or damaged. The cost of replacing eyeglasses, especially given children’s frequent changes in refractive status, hinders appropriate correction of children’s refractive errors, giving them suboptimal vision even after surgery.6 In infants and very young children, appropriate lens fitting is difficult postoperatively. In addititon, many rural families do not return for refraction until many years later, if ever. As a result of these challenges, few institutions in the developing world have been able to adopt the recommended pediatric cataract surgical protocol4; that is, extracapsular cataract extraction (ECCE) with posterior capsulotomy (PCAP), anterior vitrectomy (AV), and IOL implantation. The purchase of a vitrector machine and the use of ketamine as a general anesthetic agent 1630
have enabled the Tilganga Eye Center in Kathmandu, Nepal, to become one of the first institutions in the country to routinely perform pediatric cataract surgery. After encouraging reports of the effectiveness of IOLs in children,5–12 posterior chamber IOLs (PCIOLs) have been implanted in nearly all children operated on for cataract at the Tilganga Eye Center over the past 2 years. For the first time, the results of a consecutive series of pediatric cataract surgery cases in Nepal are reported.
Patients and Methods The study included consecutive patients younger than 15 years who had cataract surgery at Tilganga Eye Center between August 2001 and January 2003. Bilateral, unilateral, and traumatic cataract cases were included. In patients having surgery in both eyes, the second eye was operated on 2 weeks after the first eye. However, not all bilateral cataract cases had surgery in both eyes. Children presenting with acute penetrating trauma were referred to another medical center at which general endotracheal anesthesia was available. All children younger than 7 years had ECCE⫹PCAP⫹ AV⫹PCIOL, and most children older than 7 years had ECCE⫹PCIOL. A few children older than 7 years whose posterior capsule was disrupted from trauma had the former procedure. The surgical technique was standardized in each group. A scleral tunnel was made, followed by an anterior capsulotomy using a vitrector (a vitrectorhexis) in the ECCE⫹PCAP⫹ AV⫹PCIOL group and an unbent needle (V-shaped capsulotomy)13 in the ECCE⫹PCIOL group. Lens aspiration was accomplished using a Simcoe cannula or the vitrector machine set on aspiration. A separate infusion cannula was used with the vitrector aspiration to maintain the anterior chamber. In the ECCE⫹PCAP⫹AV⫹PCIOL group, the PC and AV were performed from the anterior approach before the IOL was implanted. All surgeries were done using ketamine general anesthesia with the addition of peribulbar lidocaine. The ketamine was administered intravenously by an anesthesiologist (when possible) or by someone who had been trained in airway management and resuscitation. The dose, 1 to 2 mg/kg, was given slowly over 20 to 30 seconds. Half the induction dose was given as needed throughout the course of surgery for maintenance. In children older than 2 years, 0.2 mg/kg diazepam was administered intravenously to reduce side effects after anesthesia. After the induction with ketamine, lidocaine 2% was injected into the peribulbar or retrobulbar space, followed by ocular massage for a few minutes. The patient’s vital signs and oxygen saturation were monitored throughout the procedure. Postoperatively, all eyes were given topical steroids for 6 weeks and topical tropicamide drops 3 times a day for the first few days. All children were given 1 mg/kg oral steroids
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Table 1. Distribution of pediatric patients by age group. Age (Y)
Patients
⬍1
12
1–5
21
5–10
35
10–15
17
for 7 days postoperatively. Patients had a preoperative examination by a pediatrician to confirm fitness for surgery and a postoperative examination to detect side effects from oral steroids given after surgery. Patients were examined 1 day, 1 week, 1 and 3 months, and 1 year postoperatively. At all visits, the best corrected visual acuity, fundus status, and postoperative complications were documented. When possible, intraocular pressure (IOP) was measured by Schiotz or applanation tonometry. Visual acuity in preverbal children was measured with Cardiff test cards. In children who could not cooperate, visual acuity was estimated using the child’s ability to fixate on a small, brightly colored object. In verbal children, visual acuity was measured using the Snellen E-chart or alphabetical chart. Patients were provided with spectacle prescriptions for residual distance refractive errors 1 month after surgery. No bifocals were given.
Results One hundred twelve eyes of 85 patients were operated on during the study period; 27 patients (31.8%) had bilateral surgery and 58 (68.2%), unilateral surgery. Fifty-nine patients (69.4%) were boys, and 26 (30.6%) were girls. The mean age at surgery was 6.2 years ⫾ 4.3 (SD) (range 0.25 to 15 years). The median age in the ECCE⫹PCAP⫹AV⫹PCIOL group was 4.7 years and in the ECCE⫹PCIOL group, 11.0 years. Table 1 shows the distribution of patients by age. The mean follow-up for all 112 eyes was 5.4 ⫾ 5.3 months (range 1.0 week to 1.5 years). Forty-two eyes (37.5%) had at least 1 year of follow-up. One hundred eyes (89.3%) had congenital or developmental cataract, 56 (50.0%) had total white cataract, 39 (34.8%) had lamellar or zonular cataract, and 5 (4.5%) had polar cataract. Twelve eyes (10.7%) presented with traumatic cataract. Fourteen patients (16.5%) had nystagmus before cataract surgery; the nystagmus did not completely resolve after surgery in any case. Twelve patients (14.1%) had strabismus, of which 6 (7.1%) had exotropia and 6 (7.1%) had esotropia. Four (33.3%) of the 12 patients with preoperative
strabismus had less deviation after cataract surgery. The deviation remained unchanged after surgery in the other patients. After anterior capsulotomy and lens matter aspiration, ECCE⫹PCAP⫹AV⫹PCIOL was performed in 73 eyes (65.2%) of 53 patients. Sixty-seven of these operations (91.8%) were in children younger than 7 years. In all patients in this group, the lens haptic was placed in the bag–sulcus with the optic pushed behind the posterior capsule (posterior optic capture). In 22 eyes (30.1%), the IOLs were successfully placed in the capsular bag. The IOLs were placed in the sulcus in the remainder of the cases. Thirty-nine eyes (34.8%) of 32 patients had ECCE⫹ PCIOL. After an anterior capsulotomy was created, manual lens aspiration was performed, preserving the posterior capsule. The IOL was implanted in the capsular bag. All 39 surgeries were in children older than 7 years. Methyl cellulose viscoelastic material was used in all cases. Biometry was done in 37 eyes (33.0%), all of cooperative children older than 8 years. The postoperative refractive goal in these eyes was emmetropia as not much change in refractive status is expected in older children. In eyes that did not have biometry, an IOL was implanted following these guidelines: younger than 1 year, 28.0 diopters (D); 1 to 2 years, 26.0 D; older than 2 years, 24.0 D. All eyes had a single-piece poly(methyl methacrylate) IOL (PMMA-FH 1064105) implanted. Lenses with a 5.5 mm optic and 12.5 mm overall size were used in children younger than 7 years, and IOLs with a 6.0 mm optic and 13.0 mm overall size were used in children older than 7 years. Table 2 shows the complications. The most common postoperative complication in the ECCE⫹PCIOL (posterior capsule intact) group was posterior capsule opacification (PCO), which occurred in 18 (46.2%) of 39 eyes. Most PCO cases were detected 3 months after surgery. The most common complications in the ECCE⫹PCAP⫹ AV⫹PCIOL group were visual axis opacification/PCO and distorted pupil, which occurred in 4 eyes (5.5%) each. The opacification was detected 3 months after surgery. A neodymium:YAG (Nd:YAG) capsulotomy cleared the PCO in 14 (63.6%) of the 22 eyes with visual axis opacification/PCO; in 8 cases (36.4%), the patient was taken to the operating room for vitrector removal of the opacification.
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Table 2. Postoperative complications.
Complication
ECCE⫹PCIOL Number of Eyes (%) (n ⫽ 39)
Visual axis/PCO
ECCE⫹PCAP⫹AV⫹PCIOL Number of Eyes (%) (n ⫽ 73)
18 (46.1)*
4 (5.5)*
Distorted pupil (posterior synechias)
4 (10.3)
4 (5.5)
Pupillary capture
4 (10.3)
0
Fibrinous exudates
4 (10.3)
2 (2.7)
Decentered IOL
0
2 (2.7)
AV ⫽ anterior vitrectomy; ECCE ⫽ extracapsular cataract extraction; PCAP ⫽ posterior capsulotomy; PCIOL ⫽ posterior chamber intraocular lens; PCO ⫽ posterior capsule opacification *Rate of complication statistically different between the 2 groups (P⬍.01)
There were no cases of endophthalmitis or retinal problems. There were no intraoperative complications from the ketamine. A few patients reported nausea and vomiting in the immediate postoperative period. Intraocular pressure was measured in 14 patients (16.5%); in most cases, these children were cooperative and older than 10 years. There were no cases of elevated IOP. In eyes in which the IOP could not be measured, cornea and fundus examinations revealed clear corneas and no progressive cupping of the optic disc. Of all 112 eyes, 29 (25.9%) had asymmetric amblyopia, defined as a difference in visual acuity between the 2 eyes of at least 0.2 logMAR units or clear preferential fixation in 1 eye. Asymmetric amblyopia occurred more frequently in unilateral cases (20 of 29 eyes; 69.0%) than in bilateral cataract cases (9 of 29 eyes; 31.0%). Amblyopia was managed by occlusion therapy. Of the 29 amblyopic eyes with a follow-up of at least 3 months, 24 had a visual acuity of 6/60 or better. Table 3 shows the visual acuity before and after cataract surgery.
Discussion Blindness in children remains the second leading cause of “blind-person years” worldwide.6 Visually impaired children have higher morbidity and mortality rates. Moreover, in developing countries, they face a dearth of social services for their needs. Special education for visually impaired children is unavailable and expensive in most developing countries, including Nepal. Historically, the leading cause of blindness among Nepali children has been corneal scarring secondary to measles and vitamin A deficiency.14 However, bilateral corneal blindness of these etiologies has been significantly reduced in recent years as a result of better primary health care and the success of international health promotion efforts, such as the WHO/UNICEF Extended Program of Immunization, in developing countries.15–18 In contrast, data from hospitals and screening camps suggest that the rate of childhood cataract has not decreased in recent years and that it remains a
Table 3. Visual acuity before and after cataract surgery. Postoperative 3 Mo
1Y
Visual Acuity
Preoperative Eyes (%) (n ⫽ 112)
1 Mo Eyes (%) (n ⫽ 105)
Eyes (%) (n ⫽ 71)
Eyes (%) (n ⫽ 42)
6/18 or better
6 (5.4)
26 (24.7)*
26 (36.6)*
17 (40.5)*
6/18 to 6/36
9 (8.0)
9 (8.6)
11 (15.5)
8 (19.0)
6/36 to 6/60
8 (7.1)
9 (8.6)
11 (15.5)
4 (9.5)
6/60 to 3/60
16 (14.3)
15 (14.3)
2 (2.8)
2 (4.8)
3/60 or worse
73 (65.2)
46 (43.8)†
21 (29.6)†
11 (26.2)†
*Percentage significantly higher than in preoperative group (P⬍.01) †Percentage significantly lower than in preoperative group (P⬍.01)
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leading causes of blindness in Nepal (Tilganga Eye Center Annual Report 2001–2002, pages 10–13). Our study revealed 100 eyes with congenital or developmental cataract and only 12 eyes with traumatic cataract. The number of traumatic cataracts was low because Tilganga Eye Center does not provide 24-hour surgical emergency services because of the lack of general anesthesia. Such emergency cases were referred to a tertiary-care center. There were high rates of bilateral and unilateral blindness. Details of the etiology could not be conclusively determined because of a lack of advanced genetic screening facilities. However, the absence of grossly phenotypic abnormalities or systemic disease in any patient makes major chromosomal or metabolic anomalies unlikely. The decision to operate was made on the basis of visual acuity and the likelihood of impending visual impairment. No operations were performed in children younger than 2 months because of the risks of anesthesia in very small infants in a setting in which specialized pediatric anesthesia services are unavailable. In addition, most patients presented at an older age (median 11.0 years, posterior capsule intact; 4.7 years, PCAP and vitrectomy). Sixteen percent of patients had nystagmus preoperatively. The nystagmus did not appear to improve after surgery (based on clinical observation), which is in contrast to reports in a recent study from Africa.6 Twelve (14.1%) of the 85 patients had strabismus preoperatively, which improved after surgery in 4 cases (33.3%). This is comparable to outcomes reported in the literature.6,9 Our complication rates compared favorably to those reported in the literature.3,6–9,11,12 Postoperative PCO is nearly universal in children after extracapsular cataract surgery. A study in India showed that most children required capsulotomy after lens aspiration.8 In our series, only 4 of 73 eyes (5.5%) having ECCE⫹PCAP⫹ AV⫹PCIOL had visual axis opacification/PCO compared to 18 of 39 eyes (46.2%) in the ECCE⫹PCIOL group. This series confirms previous work4,6,7,9 that recommended PCAP and AV in children. Although an Nd:YAG capsulotomy is easier to perform in older children, a surgical capsulotomy at the time of lens aspiration might be recommended in developing countries, where many patients are lost to follow-up. Regarding time of onset of PCO, it has been reported to peak around 18 months after surgery in eyes with an intact posterior
capsule19; in our series PCO occurred much earlier, an average of 3 months after surgery. In contrast, it has been reported that visual axis opacification occurs within 6 months after surgery in eyes having ECCE⫹PCAP⫹ AV⫹PCIOL,20 which corresponds to our data showing that opacification appeared at an average of 3 months after surgery in the AV group. Fibrinous uveitis occurred in less than 10% of the 112 eyes, a rate lower than that in other studies.7,8 No eye in the ECCE⫹PCAP⫹AV⫹PCIOL group and 4 eyes (10.3%) in the ECCE⫹PCIOL group had pupillary capture, primarily because the optic was pushed behind the capsule (posterior optic capture) in the former group. The distorted pupils in both groups were the result of posterior synechias, most commonly secondary to postoperative inflammation, which may have resulted from poor patient compliance with steroid drops and oral steroids. There were 2 cases of a decentered IOL in eyes having AV and in no eyes in which the posterior capsule was intact. The 2 dislocated IOLs were the result of a lack of posterior capsule support, allowing the lens to dislocate slightly inferiorly. Both cases were in eyes with traumatic cataract with extensive disruption of the posterior capsule. Glaucoma was not detected in either group. The IOP could be recorded in 14 patients and was normal in all of them. Moreover, all patients had clear corneas and no progressive cupping on fundus examination. There were no cases of retinal detachment or hemorrhage. However, the mean followup was only 5.4 months and more complications may be seen over a longer period. The visual results are encouraging. Of eyes with a minimum follow-up of 3 months, 68% had a visual acuity of 6/60 or better at the last visit. The worse results in younger children are probably because there was a greater frequency of mature cataract in this age group, leading to more severe visual deprivation during the critical period of visual development. A higher percentage of eyes with an intact posterior capsule than eyes that had an AV achieved a visual acuity of 6/18 or better, probably because of the preponderance of lamellar cataract in the former group. These patients had not developed as much deprivation amblyopia as the latter group, in which most eyes had total cataract at the time of surgery. In addition, the AV group consisted of many infants and toddlers who were still preverbal at their last follow-up visit. Among these often
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uncooperative patients, visual acuity was difficult to record objectively and accurately. Therefore, despite having clear visual axes, their acuities were recorded as 0.5/60 or worse, overestimating poor visual outcomes in the AV group. Finally, worse visual outcomes in younger children could be because parents were somewhat less likely to provide corrective lenses in younger children than in older ones, especially if the child’s prescription changed over time. Late presentation leading to deprivation amblyopia was the primary cause of a poor visual outcome. Most children operated on before the age of 6 years would have had some degree of amblyopia in both eyes. Asymmetric amblyopia was treated by occlusion. Amblyopia occurred more often in unilateral cases than in bilateral cases. Biometry was not uniformly performed in our series as most patients were unable to cooperate sufficiently to obtain accurate keratometry readings. Moreover, biometry was not performed when the children were sedated because of technical and logistical limitations. Most important, Tilganga Eye Center has only 1 set of keratometry/biometry machines, which are in great demand to meet the heavy adult patient volume. Additional machinery will be needed to do biometry under anesthesia in younger children. During the current study, it was not feasible to carry these machines from the adult clinic to the operating theater for pediatric cataract cases. The use and regimen of steroids after pediatric cataract surgery have been debated. Our patients received a higher dose of steroids because it is hypothesized that young, more heavily pigmented eyes have more postoperative inflammation than eyes with lighter irides.21 No patient showed obvious side effects from the 7-day course of oral steroids, and we believe the oral regimen led to less inflammation. As reported elsewhere,22 our study suggests that ketamine is an effective agent for ocular surgery in pediatric patients. No child in our series needed resuscitation or intubation, and the ophthalmic surgery was performed safely. Ketamine is cost effective, and patients recover quickly after surgery. In settings in which there is a scarcity of trained anesthesiologists, ketamine can be administered by a person with basic training in resuscitation protocol, making it a good anesthesia choice in developing countries.23–25 1634
The rates of follow-up in our study are somewhat lower than those reported elsewhere.6,7,9 Although the underlying reasons are many, the cost of travel to the clinic and of follow-up care, as well as the wage-earning hours the parents lose, are among the most significant. As most families in Nepal have several children, parents are reluctant to take scarce resources for health care and education away from their “normal” children and use them for a child who may not become economically independent. Nonetheless, the results of this first large study of pediatric cataract surgeries in Nepal are promising and show that ECCE⫹PCIOL implantation (with or without AV and PCAP) under ketamine anesthesia is a safe procedure with a low complication rate and good visual outcomes.
Conclusion Cataract is a leading cause of blindness in children in the developing world. This study demonstrates that good results can be obtained in countries like Nepal by using IOLs. In the short term, there appears to be little risk for blinding complications from the presence of an IOL; thus, IOL implantation can be made a standard treatment of choice for most children with cataract in Nepal. This treatment will be cost effective and will reduce the problems associated with lost and broken aphakic glasses or expensive contact lenses. Ketamine in conjunction with peribulbar anesthesia can also be made the standard choice of general anesthesia in developing countries when other sources of general anesthesia are unavailable.
References 1. Thylefors B, Negrel AD, Pararajasegaram R, Dadzie KY. Global data on blindness. Bull World Health Organ 1995; 73:115–121 2. Foster A, Gilbert C, Rahi J. Epidemiology of cataract in childhood: a global perspective. J Cataract Refract Surg 1997; 23:601–604 3. Rahi JS, Gilbert CE, Foster A, Minassian D. Measuring the burden of childhood blindness [commentary]. Br J Ophthalmol 1999; 83:387–388 4. Wilson ME, Pandey SK, Thakur J. Paediatric cataract blindness in the developing world: surgical techniques and intraocular lenses in the new millennium. Br J Ophthalmol 2003; 87:14–19
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5. Wilson ME. Intraocular lens implantation: has it become the standard of care for children? [guest editorial] Ophthalmology 1996; 103:1719–1720 6. Yorston D, Wood M, Foster A. Results of cataract surgery in young children in east Africa. Br J Ophthalmol 2001; 85:267–271 7. Basti S, Ravishankar U, Gupta S. Results of a prospective evaluation of three methods of management of pediatric cataracts. Ophthalmology 1996; 103:713–720 8. Venkataswamy G. Intraocular lens implantation in India [letter]. Ophthalmic Surg 1990; 21:866–867 9. Eckstein M, Vijayalakshmi P, Gilbert C, Foster A. Randomised clinical trial of lensectomy versus lens aspiration and primary capsulotomy for children with bilateral cataract in south India. Br J Ophthalmol 1999; 83:524–529 10. Markham RHC, Bloom PA, Chandna A, Newcomb EH. Results of intraocular lens implantation in paediatric aphakia. Eye 1992; 6:493–498 11. Young TL, Bloom JN, Ruttum M, et al. The IOLAB, Inc Pediatric Intraocular Lens Study; AAPOS Research Committee. J AAPOS 1999; 3:295–302 12. Er H, Doganay S, Evereklioglu C, et al. Retrospective comparison of surgical techniques to prevent secondary opacification in pediatric cataracts. J Pediatr Ophthalmol Strabismus 2000; 37:294–298 13. Ruit S, Tabin GC, Nissman SA, et al. Low-cost, highvolume extracapsular cataract extraction with posterior chamber intraocular lens implantation in Nepal. Ophthalmology 1999; 106:1887–1892 14. Brilliant GE. The epidemiology of blindness in Nepal: report of the 1981 Nepal blindness survey. Chelsea, MI, Seva Foundation, 1988 15. Pokharel GP, Pant CR, Tilden RL, et al. Nutrition education and mega-dose vitamin A supplementation in Nepal. Indian J Pediatr 1998; 65:547–555 16. Pant CR, Pokharel GP, Curtale F, et al. Impact of nutrition education and mega-dose vitamin A supplementation on the health of children in Nepal. Bull World Health Organ 1996; 74:533–545 17. Fiedler JL. The Nepal National Vitamin A Program: prototype to emulate or donor enclave? Health Policy Plan 2000; 15:145–156
18. Foster A, Yorston D. Corneal ulceration in Tanzanian children: relationship between measles and vitamin A deficiency. Trans R Soc Trop Med Hyg 1992; 86:454– 455 19. Plager DA, Lipsky SN, Snyder SK, et al. Capsular management and refractive error in pediatric intraocular lenses. Ophthalmology 1997; 104:600–607; discussion by AW Biglan, 607 20. Trivedi RH, Wilson ME, Bartholomew LR, et al. Opacification of the visual axis after cataract surgery and single acrylic intraocular lens implantation in the first year-oflife. J AAPOS 2004; 8:156–164 21. Yorston D. Intraocular lens (IOL) implants in children. Community Eye Health 2001; 14:57–58 22. Pun MS, Thakur J, Poudyal G, et al. Ketamine anaesthesia for paediatric ophthalmology surgery. Br J Ophthalmol 2003; 87:535–537 23. Green SM, Rothrock SG, Lynch EL, et al. Intramuscular ketamine for pediatric sedation in the emergency department: safety profile in 1,022 cases. Ann Emerg Med 1998; 31:688–697 24. Adesunkanmi AR. Where there is no anaesthetist: a study of 282 consecutive patients using intravenous, spinal and local infiltration anaesthetic techniques. Trop Doct 1997; 27:79–82 25. Green SM, Clem KJ, Rothrock SG. Ketamine safety profile in the developing world: survey of practitioners. Acad Emerg Med 1996; 3:598–604 From Tilganga Eye Center (Thakur, Reddy, Paudyal, Gurung, Thapa, Tabin, Ruit), Kathmandu, Nepal; Harvard Medical School (Reddy), Boston, Massachusetts, Storm Eye Institute, Medical University of South Carolina (Wilson), Charleston, South Carolina, and University of Vermont (Tabin), Burlington, Vermont, USA. Supported in part by NIH EY014793 and an unrestricted grant to MUSC–Storm Eye Institute from Research to Prevent Blindness, New York, New York, USA. None of the authors has a financial or proprietary interest in any material or method mentioned. Anil Paudyal, ophthalmic assistant, Tilganga Eye Center, assisted in the completion of this paper, and Dr. Luanna Bartholomew provided critical review.
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T
he World Health Organization’s (WHO) global initiative for the elimination of avoidable blindness by the year 20201 has identified the control of childhood blindness as a priority. Cataract remains one of the most important causes of avoidable blindness in children. Worldwide, an estimated 200 000 children are currently Accepted for publication December 23, 2003. Reprint requests to M. Edward Wilson, Jr, MD, MUSC–Storm Eye Institute, 167 Ashley Avenue, Charleston, South Carolina 29425-5536, USA. E-mail [email protected]. 2004 ASCRS and ESCRS Published by Elsevier Inc.
blind from cataract, and every year 20 000 to 40 000 neonates are born with congenital cataract.2 The burden of illness disproportionately affects the developing world, where the prevalence of cataract blindness is 10 times higher than in developed countries.3 Pediatric cataract takes an enormous toll on developing countries in the form of human morbidity, economic loss, and social burden.4 Many infants with debilitating cataracts do not survive childhood. For those who do, the long-term burden of disability is tremendous. A child who goes blind today is likely to 0886-3350/04/$–see front matter doi:10.1016/j.jcrs.2003.12.047
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live until 2050.1 Accordingly, restoring this child’s sight may be equivalent to restoring the sight of 10 elderly adults1 in terms of “blind years” avoided, gained productivity, and overall savings to society. In Nepal, as in other developing countries, cataract is believed to be a leading cause of blindness in children. Although no formal data on the prevalence of the disease have been published, many pediatric cataract cases are routinely seen in outpatient hospital settings and screening camps organized by local charities (Tilganga Eye Center Annual Report, 2001–2002, pages 10–13). A dedicated team effort with advanced technological resources is required to manage childhood cataract.4 Because of the lack of advanced technology in many developing countries, surgical outcomes there have traditionally been very poor. In Nepal, a significant barrier to effective cataract surgery has been a lack of equipment, in particular the automated suction-cutting (vitrector) machine. A shortage of trained anesthesiologists and the expense of advanced monitoring equipment have also made it difficult for ophthalmic surgical centers to set up and maintain advanced monitored-anesthesia protocols for children.4 As a result, few ophthalmic procedures are currently done under conventional general anesthesia in Nepal. In addition, implanting intraocular lenses (IOLs) in pediatric eyes has only recently been accepted, even in older children.5 Postoperative refractive change with ocular growth in children presents another challenge. However, the price and maintenance of contact lenses make them impractical for most families in the developing world and aphakic eyeglasses are often lost or damaged. The cost of replacing eyeglasses, especially given children’s frequent changes in refractive status, hinders appropriate correction of children’s refractive errors, giving them suboptimal vision even after surgery.6 In infants and very young children, appropriate lens fitting is difficult postoperatively. In addititon, many rural families do not return for refraction until many years later, if ever. As a result of these challenges, few institutions in the developing world have been able to adopt the recommended pediatric cataract surgical protocol4; that is, extracapsular cataract extraction (ECCE) with posterior capsulotomy (PCAP), anterior vitrectomy (AV), and IOL implantation. The purchase of a vitrector machine and the use of ketamine as a general anesthetic agent 1630
have enabled the Tilganga Eye Center in Kathmandu, Nepal, to become one of the first institutions in the country to routinely perform pediatric cataract surgery. After encouraging reports of the effectiveness of IOLs in children,5–12 posterior chamber IOLs (PCIOLs) have been implanted in nearly all children operated on for cataract at the Tilganga Eye Center over the past 2 years. For the first time, the results of a consecutive series of pediatric cataract surgery cases in Nepal are reported.
Patients and Methods The study included consecutive patients younger than 15 years who had cataract surgery at Tilganga Eye Center between August 2001 and January 2003. Bilateral, unilateral, and traumatic cataract cases were included. In patients having surgery in both eyes, the second eye was operated on 2 weeks after the first eye. However, not all bilateral cataract cases had surgery in both eyes. Children presenting with acute penetrating trauma were referred to another medical center at which general endotracheal anesthesia was available. All children younger than 7 years had ECCE⫹PCAP⫹ AV⫹PCIOL, and most children older than 7 years had ECCE⫹PCIOL. A few children older than 7 years whose posterior capsule was disrupted from trauma had the former procedure. The surgical technique was standardized in each group. A scleral tunnel was made, followed by an anterior capsulotomy using a vitrector (a vitrectorhexis) in the ECCE⫹PCAP⫹ AV⫹PCIOL group and an unbent needle (V-shaped capsulotomy)13 in the ECCE⫹PCIOL group. Lens aspiration was accomplished using a Simcoe cannula or the vitrector machine set on aspiration. A separate infusion cannula was used with the vitrector aspiration to maintain the anterior chamber. In the ECCE⫹PCAP⫹AV⫹PCIOL group, the PC and AV were performed from the anterior approach before the IOL was implanted. All surgeries were done using ketamine general anesthesia with the addition of peribulbar lidocaine. The ketamine was administered intravenously by an anesthesiologist (when possible) or by someone who had been trained in airway management and resuscitation. The dose, 1 to 2 mg/kg, was given slowly over 20 to 30 seconds. Half the induction dose was given as needed throughout the course of surgery for maintenance. In children older than 2 years, 0.2 mg/kg diazepam was administered intravenously to reduce side effects after anesthesia. After the induction with ketamine, lidocaine 2% was injected into the peribulbar or retrobulbar space, followed by ocular massage for a few minutes. The patient’s vital signs and oxygen saturation were monitored throughout the procedure. Postoperatively, all eyes were given topical steroids for 6 weeks and topical tropicamide drops 3 times a day for the first few days. All children were given 1 mg/kg oral steroids
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Table 1. Distribution of pediatric patients by age group. Age (Y)
Patients
⬍1
12
1–5
21
5–10
35
10–15
17
for 7 days postoperatively. Patients had a preoperative examination by a pediatrician to confirm fitness for surgery and a postoperative examination to detect side effects from oral steroids given after surgery. Patients were examined 1 day, 1 week, 1 and 3 months, and 1 year postoperatively. At all visits, the best corrected visual acuity, fundus status, and postoperative complications were documented. When possible, intraocular pressure (IOP) was measured by Schiotz or applanation tonometry. Visual acuity in preverbal children was measured with Cardiff test cards. In children who could not cooperate, visual acuity was estimated using the child’s ability to fixate on a small, brightly colored object. In verbal children, visual acuity was measured using the Snellen E-chart or alphabetical chart. Patients were provided with spectacle prescriptions for residual distance refractive errors 1 month after surgery. No bifocals were given.
Results One hundred twelve eyes of 85 patients were operated on during the study period; 27 patients (31.8%) had bilateral surgery and 58 (68.2%), unilateral surgery. Fifty-nine patients (69.4%) were boys, and 26 (30.6%) were girls. The mean age at surgery was 6.2 years ⫾ 4.3 (SD) (range 0.25 to 15 years). The median age in the ECCE⫹PCAP⫹AV⫹PCIOL group was 4.7 years and in the ECCE⫹PCIOL group, 11.0 years. Table 1 shows the distribution of patients by age. The mean follow-up for all 112 eyes was 5.4 ⫾ 5.3 months (range 1.0 week to 1.5 years). Forty-two eyes (37.5%) had at least 1 year of follow-up. One hundred eyes (89.3%) had congenital or developmental cataract, 56 (50.0%) had total white cataract, 39 (34.8%) had lamellar or zonular cataract, and 5 (4.5%) had polar cataract. Twelve eyes (10.7%) presented with traumatic cataract. Fourteen patients (16.5%) had nystagmus before cataract surgery; the nystagmus did not completely resolve after surgery in any case. Twelve patients (14.1%) had strabismus, of which 6 (7.1%) had exotropia and 6 (7.1%) had esotropia. Four (33.3%) of the 12 patients with preoperative
strabismus had less deviation after cataract surgery. The deviation remained unchanged after surgery in the other patients. After anterior capsulotomy and lens matter aspiration, ECCE⫹PCAP⫹AV⫹PCIOL was performed in 73 eyes (65.2%) of 53 patients. Sixty-seven of these operations (91.8%) were in children younger than 7 years. In all patients in this group, the lens haptic was placed in the bag–sulcus with the optic pushed behind the posterior capsule (posterior optic capture). In 22 eyes (30.1%), the IOLs were successfully placed in the capsular bag. The IOLs were placed in the sulcus in the remainder of the cases. Thirty-nine eyes (34.8%) of 32 patients had ECCE⫹ PCIOL. After an anterior capsulotomy was created, manual lens aspiration was performed, preserving the posterior capsule. The IOL was implanted in the capsular bag. All 39 surgeries were in children older than 7 years. Methyl cellulose viscoelastic material was used in all cases. Biometry was done in 37 eyes (33.0%), all of cooperative children older than 8 years. The postoperative refractive goal in these eyes was emmetropia as not much change in refractive status is expected in older children. In eyes that did not have biometry, an IOL was implanted following these guidelines: younger than 1 year, 28.0 diopters (D); 1 to 2 years, 26.0 D; older than 2 years, 24.0 D. All eyes had a single-piece poly(methyl methacrylate) IOL (PMMA-FH 1064105) implanted. Lenses with a 5.5 mm optic and 12.5 mm overall size were used in children younger than 7 years, and IOLs with a 6.0 mm optic and 13.0 mm overall size were used in children older than 7 years. Table 2 shows the complications. The most common postoperative complication in the ECCE⫹PCIOL (posterior capsule intact) group was posterior capsule opacification (PCO), which occurred in 18 (46.2%) of 39 eyes. Most PCO cases were detected 3 months after surgery. The most common complications in the ECCE⫹PCAP⫹ AV⫹PCIOL group were visual axis opacification/PCO and distorted pupil, which occurred in 4 eyes (5.5%) each. The opacification was detected 3 months after surgery. A neodymium:YAG (Nd:YAG) capsulotomy cleared the PCO in 14 (63.6%) of the 22 eyes with visual axis opacification/PCO; in 8 cases (36.4%), the patient was taken to the operating room for vitrector removal of the opacification.
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Table 2. Postoperative complications.
Complication
ECCE⫹PCIOL Number of Eyes (%) (n ⫽ 39)
Visual axis/PCO
ECCE⫹PCAP⫹AV⫹PCIOL Number of Eyes (%) (n ⫽ 73)
18 (46.1)*
4 (5.5)*
Distorted pupil (posterior synechias)
4 (10.3)
4 (5.5)
Pupillary capture
4 (10.3)
0
Fibrinous exudates
4 (10.3)
2 (2.7)
Decentered IOL
0
2 (2.7)
AV ⫽ anterior vitrectomy; ECCE ⫽ extracapsular cataract extraction; PCAP ⫽ posterior capsulotomy; PCIOL ⫽ posterior chamber intraocular lens; PCO ⫽ posterior capsule opacification *Rate of complication statistically different between the 2 groups (P⬍.01)
There were no cases of endophthalmitis or retinal problems. There were no intraoperative complications from the ketamine. A few patients reported nausea and vomiting in the immediate postoperative period. Intraocular pressure was measured in 14 patients (16.5%); in most cases, these children were cooperative and older than 10 years. There were no cases of elevated IOP. In eyes in which the IOP could not be measured, cornea and fundus examinations revealed clear corneas and no progressive cupping of the optic disc. Of all 112 eyes, 29 (25.9%) had asymmetric amblyopia, defined as a difference in visual acuity between the 2 eyes of at least 0.2 logMAR units or clear preferential fixation in 1 eye. Asymmetric amblyopia occurred more frequently in unilateral cases (20 of 29 eyes; 69.0%) than in bilateral cataract cases (9 of 29 eyes; 31.0%). Amblyopia was managed by occlusion therapy. Of the 29 amblyopic eyes with a follow-up of at least 3 months, 24 had a visual acuity of 6/60 or better. Table 3 shows the visual acuity before and after cataract surgery.
Discussion Blindness in children remains the second leading cause of “blind-person years” worldwide.6 Visually impaired children have higher morbidity and mortality rates. Moreover, in developing countries, they face a dearth of social services for their needs. Special education for visually impaired children is unavailable and expensive in most developing countries, including Nepal. Historically, the leading cause of blindness among Nepali children has been corneal scarring secondary to measles and vitamin A deficiency.14 However, bilateral corneal blindness of these etiologies has been significantly reduced in recent years as a result of better primary health care and the success of international health promotion efforts, such as the WHO/UNICEF Extended Program of Immunization, in developing countries.15–18 In contrast, data from hospitals and screening camps suggest that the rate of childhood cataract has not decreased in recent years and that it remains a
Table 3. Visual acuity before and after cataract surgery. Postoperative 3 Mo
1Y
Visual Acuity
Preoperative Eyes (%) (n ⫽ 112)
1 Mo Eyes (%) (n ⫽ 105)
Eyes (%) (n ⫽ 71)
Eyes (%) (n ⫽ 42)
6/18 or better
6 (5.4)
26 (24.7)*
26 (36.6)*
17 (40.5)*
6/18 to 6/36
9 (8.0)
9 (8.6)
11 (15.5)
8 (19.0)
6/36 to 6/60
8 (7.1)
9 (8.6)
11 (15.5)
4 (9.5)
6/60 to 3/60
16 (14.3)
15 (14.3)
2 (2.8)
2 (4.8)
3/60 or worse
73 (65.2)
46 (43.8)†
21 (29.6)†
11 (26.2)†
*Percentage significantly higher than in preoperative group (P⬍.01) †Percentage significantly lower than in preoperative group (P⬍.01)
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leading causes of blindness in Nepal (Tilganga Eye Center Annual Report 2001–2002, pages 10–13). Our study revealed 100 eyes with congenital or developmental cataract and only 12 eyes with traumatic cataract. The number of traumatic cataracts was low because Tilganga Eye Center does not provide 24-hour surgical emergency services because of the lack of general anesthesia. Such emergency cases were referred to a tertiary-care center. There were high rates of bilateral and unilateral blindness. Details of the etiology could not be conclusively determined because of a lack of advanced genetic screening facilities. However, the absence of grossly phenotypic abnormalities or systemic disease in any patient makes major chromosomal or metabolic anomalies unlikely. The decision to operate was made on the basis of visual acuity and the likelihood of impending visual impairment. No operations were performed in children younger than 2 months because of the risks of anesthesia in very small infants in a setting in which specialized pediatric anesthesia services are unavailable. In addition, most patients presented at an older age (median 11.0 years, posterior capsule intact; 4.7 years, PCAP and vitrectomy). Sixteen percent of patients had nystagmus preoperatively. The nystagmus did not appear to improve after surgery (based on clinical observation), which is in contrast to reports in a recent study from Africa.6 Twelve (14.1%) of the 85 patients had strabismus preoperatively, which improved after surgery in 4 cases (33.3%). This is comparable to outcomes reported in the literature.6,9 Our complication rates compared favorably to those reported in the literature.3,6–9,11,12 Postoperative PCO is nearly universal in children after extracapsular cataract surgery. A study in India showed that most children required capsulotomy after lens aspiration.8 In our series, only 4 of 73 eyes (5.5%) having ECCE⫹PCAP⫹ AV⫹PCIOL had visual axis opacification/PCO compared to 18 of 39 eyes (46.2%) in the ECCE⫹PCIOL group. This series confirms previous work4,6,7,9 that recommended PCAP and AV in children. Although an Nd:YAG capsulotomy is easier to perform in older children, a surgical capsulotomy at the time of lens aspiration might be recommended in developing countries, where many patients are lost to follow-up. Regarding time of onset of PCO, it has been reported to peak around 18 months after surgery in eyes with an intact posterior
capsule19; in our series PCO occurred much earlier, an average of 3 months after surgery. In contrast, it has been reported that visual axis opacification occurs within 6 months after surgery in eyes having ECCE⫹PCAP⫹ AV⫹PCIOL,20 which corresponds to our data showing that opacification appeared at an average of 3 months after surgery in the AV group. Fibrinous uveitis occurred in less than 10% of the 112 eyes, a rate lower than that in other studies.7,8 No eye in the ECCE⫹PCAP⫹AV⫹PCIOL group and 4 eyes (10.3%) in the ECCE⫹PCIOL group had pupillary capture, primarily because the optic was pushed behind the capsule (posterior optic capture) in the former group. The distorted pupils in both groups were the result of posterior synechias, most commonly secondary to postoperative inflammation, which may have resulted from poor patient compliance with steroid drops and oral steroids. There were 2 cases of a decentered IOL in eyes having AV and in no eyes in which the posterior capsule was intact. The 2 dislocated IOLs were the result of a lack of posterior capsule support, allowing the lens to dislocate slightly inferiorly. Both cases were in eyes with traumatic cataract with extensive disruption of the posterior capsule. Glaucoma was not detected in either group. The IOP could be recorded in 14 patients and was normal in all of them. Moreover, all patients had clear corneas and no progressive cupping on fundus examination. There were no cases of retinal detachment or hemorrhage. However, the mean followup was only 5.4 months and more complications may be seen over a longer period. The visual results are encouraging. Of eyes with a minimum follow-up of 3 months, 68% had a visual acuity of 6/60 or better at the last visit. The worse results in younger children are probably because there was a greater frequency of mature cataract in this age group, leading to more severe visual deprivation during the critical period of visual development. A higher percentage of eyes with an intact posterior capsule than eyes that had an AV achieved a visual acuity of 6/18 or better, probably because of the preponderance of lamellar cataract in the former group. These patients had not developed as much deprivation amblyopia as the latter group, in which most eyes had total cataract at the time of surgery. In addition, the AV group consisted of many infants and toddlers who were still preverbal at their last follow-up visit. Among these often
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uncooperative patients, visual acuity was difficult to record objectively and accurately. Therefore, despite having clear visual axes, their acuities were recorded as 0.5/60 or worse, overestimating poor visual outcomes in the AV group. Finally, worse visual outcomes in younger children could be because parents were somewhat less likely to provide corrective lenses in younger children than in older ones, especially if the child’s prescription changed over time. Late presentation leading to deprivation amblyopia was the primary cause of a poor visual outcome. Most children operated on before the age of 6 years would have had some degree of amblyopia in both eyes. Asymmetric amblyopia was treated by occlusion. Amblyopia occurred more often in unilateral cases than in bilateral cases. Biometry was not uniformly performed in our series as most patients were unable to cooperate sufficiently to obtain accurate keratometry readings. Moreover, biometry was not performed when the children were sedated because of technical and logistical limitations. Most important, Tilganga Eye Center has only 1 set of keratometry/biometry machines, which are in great demand to meet the heavy adult patient volume. Additional machinery will be needed to do biometry under anesthesia in younger children. During the current study, it was not feasible to carry these machines from the adult clinic to the operating theater for pediatric cataract cases. The use and regimen of steroids after pediatric cataract surgery have been debated. Our patients received a higher dose of steroids because it is hypothesized that young, more heavily pigmented eyes have more postoperative inflammation than eyes with lighter irides.21 No patient showed obvious side effects from the 7-day course of oral steroids, and we believe the oral regimen led to less inflammation. As reported elsewhere,22 our study suggests that ketamine is an effective agent for ocular surgery in pediatric patients. No child in our series needed resuscitation or intubation, and the ophthalmic surgery was performed safely. Ketamine is cost effective, and patients recover quickly after surgery. In settings in which there is a scarcity of trained anesthesiologists, ketamine can be administered by a person with basic training in resuscitation protocol, making it a good anesthesia choice in developing countries.23–25 1634
The rates of follow-up in our study are somewhat lower than those reported elsewhere.6,7,9 Although the underlying reasons are many, the cost of travel to the clinic and of follow-up care, as well as the wage-earning hours the parents lose, are among the most significant. As most families in Nepal have several children, parents are reluctant to take scarce resources for health care and education away from their “normal” children and use them for a child who may not become economically independent. Nonetheless, the results of this first large study of pediatric cataract surgeries in Nepal are promising and show that ECCE⫹PCIOL implantation (with or without AV and PCAP) under ketamine anesthesia is a safe procedure with a low complication rate and good visual outcomes.
Conclusion Cataract is a leading cause of blindness in children in the developing world. This study demonstrates that good results can be obtained in countries like Nepal by using IOLs. In the short term, there appears to be little risk for blinding complications from the presence of an IOL; thus, IOL implantation can be made a standard treatment of choice for most children with cataract in Nepal. This treatment will be cost effective and will reduce the problems associated with lost and broken aphakic glasses or expensive contact lenses. Ketamine in conjunction with peribulbar anesthesia can also be made the standard choice of general anesthesia in developing countries when other sources of general anesthesia are unavailable.
References 1. Thylefors B, Negrel AD, Pararajasegaram R, Dadzie KY. Global data on blindness. Bull World Health Organ 1995; 73:115–121 2. Foster A, Gilbert C, Rahi J. Epidemiology of cataract in childhood: a global perspective. J Cataract Refract Surg 1997; 23:601–604 3. Rahi JS, Gilbert CE, Foster A, Minassian D. Measuring the burden of childhood blindness [commentary]. Br J Ophthalmol 1999; 83:387–388 4. Wilson ME, Pandey SK, Thakur J. Paediatric cataract blindness in the developing world: surgical techniques and intraocular lenses in the new millennium. Br J Ophthalmol 2003; 87:14–19
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5. Wilson ME. Intraocular lens implantation: has it become the standard of care for children? [guest editorial] Ophthalmology 1996; 103:1719–1720 6. Yorston D, Wood M, Foster A. Results of cataract surgery in young children in east Africa. Br J Ophthalmol 2001; 85:267–271 7. Basti S, Ravishankar U, Gupta S. Results of a prospective evaluation of three methods of management of pediatric cataracts. Ophthalmology 1996; 103:713–720 8. Venkataswamy G. Intraocular lens implantation in India [letter]. Ophthalmic Surg 1990; 21:866–867 9. Eckstein M, Vijayalakshmi P, Gilbert C, Foster A. Randomised clinical trial of lensectomy versus lens aspiration and primary capsulotomy for children with bilateral cataract in south India. Br J Ophthalmol 1999; 83:524–529 10. Markham RHC, Bloom PA, Chandna A, Newcomb EH. Results of intraocular lens implantation in paediatric aphakia. Eye 1992; 6:493–498 11. Young TL, Bloom JN, Ruttum M, et al. The IOLAB, Inc Pediatric Intraocular Lens Study; AAPOS Research Committee. J AAPOS 1999; 3:295–302 12. Er H, Doganay S, Evereklioglu C, et al. Retrospective comparison of surgical techniques to prevent secondary opacification in pediatric cataracts. J Pediatr Ophthalmol Strabismus 2000; 37:294–298 13. Ruit S, Tabin GC, Nissman SA, et al. Low-cost, highvolume extracapsular cataract extraction with posterior chamber intraocular lens implantation in Nepal. Ophthalmology 1999; 106:1887–1892 14. Brilliant GE. The epidemiology of blindness in Nepal: report of the 1981 Nepal blindness survey. Chelsea, MI, Seva Foundation, 1988 15. Pokharel GP, Pant CR, Tilden RL, et al. Nutrition education and mega-dose vitamin A supplementation in Nepal. Indian J Pediatr 1998; 65:547–555 16. Pant CR, Pokharel GP, Curtale F, et al. Impact of nutrition education and mega-dose vitamin A supplementation on the health of children in Nepal. Bull World Health Organ 1996; 74:533–545 17. Fiedler JL. The Nepal National Vitamin A Program: prototype to emulate or donor enclave? Health Policy Plan 2000; 15:145–156
18. Foster A, Yorston D. Corneal ulceration in Tanzanian children: relationship between measles and vitamin A deficiency. Trans R Soc Trop Med Hyg 1992; 86:454– 455 19. Plager DA, Lipsky SN, Snyder SK, et al. Capsular management and refractive error in pediatric intraocular lenses. Ophthalmology 1997; 104:600–607; discussion by AW Biglan, 607 20. Trivedi RH, Wilson ME, Bartholomew LR, et al. Opacification of the visual axis after cataract surgery and single acrylic intraocular lens implantation in the first year-oflife. J AAPOS 2004; 8:156–164 21. Yorston D. Intraocular lens (IOL) implants in children. Community Eye Health 2001; 14:57–58 22. Pun MS, Thakur J, Poudyal G, et al. Ketamine anaesthesia for paediatric ophthalmology surgery. Br J Ophthalmol 2003; 87:535–537 23. Green SM, Rothrock SG, Lynch EL, et al. Intramuscular ketamine for pediatric sedation in the emergency department: safety profile in 1,022 cases. Ann Emerg Med 1998; 31:688–697 24. Adesunkanmi AR. Where there is no anaesthetist: a study of 282 consecutive patients using intravenous, spinal and local infiltration anaesthetic techniques. Trop Doct 1997; 27:79–82 25. Green SM, Clem KJ, Rothrock SG. Ketamine safety profile in the developing world: survey of practitioners. Acad Emerg Med 1996; 3:598–604 From Tilganga Eye Center (Thakur, Reddy, Paudyal, Gurung, Thapa, Tabin, Ruit), Kathmandu, Nepal; Harvard Medical School (Reddy), Boston, Massachusetts, Storm Eye Institute, Medical University of South Carolina (Wilson), Charleston, South Carolina, and University of Vermont (Tabin), Burlington, Vermont, USA. Supported in part by NIH EY014793 and an unrestricted grant to MUSC–Storm Eye Institute from Research to Prevent Blindness, New York, New York, USA. None of the authors has a financial or proprietary interest in any material or method mentioned. Anil Paudyal, ophthalmic assistant, Tilganga Eye Center, assisted in the completion of this paper, and Dr. Luanna Bartholomew provided critical review.
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