Article Text
Abstract
Aim To report the results of paediatric cataract surgery with primary intraocular lens (IOL) implantation.
Methods Children with congenital or developmental cataract who underwent phacoaspiration with posterior chamber (PC) IOL implantation were retrospectively studied. Group A included children with polymethyl methacrylate, group B hydrophobic acrylic and group C silicone IOLs. Outcome measures were visual axis clarity, visual outcome and refractive changes.
Results There were 230 children (381 eyes) with the age ranging from 1 months to 15 years. Group A comprised 208, group B 144 and group C 29 eyes. Posterior capsule opacification was seen in 38/208 in group A and 21/144 in group B and 4/29 eyes in group C. The mean refractive error at 2 weeks, 1 year and 3 years after cataract surgery in the age group ≤2 years was +3.38±3.07 D (median +3.75 D), +1.72 D±3.19 (median +1 D) and −0.51 D±3.59 (median −0.5 D); in the age group >2–8 years +0.84±3.18 D (median+1.5 D), +0.27 D±3.14 (median +0.5 D) and −0.62 D±2.81(median −0.75D); and in the age group >8 years −0.44±1.73 D (median −0.5 D), −0.70±1.77 D (median −0.75 D) and −0.89 D±1.60 (median −0.75D) respectively. Children ≤2 years had a significant myopic shift (p<0.001). LogMAR visual acuity was ≥0.3 in 62.2% of eyes in bilateral and 30.90% in the unilateral group.
Conclusions Paediatric cataract surgery with primary PCIOL implantation is safe. Refractive changes and PCO are the main hurdles for achieving optimal visual outcome.
- Paediatric cataract
- intraocular lens
- cataract surgery
- posterior capsular opacification
- visual outcome
- posterior chamber
- lens and zonules
- vision
- treatment surgery
- child health (paediatrics)
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- Paediatric cataract
- intraocular lens
- cataract surgery
- posterior capsular opacification
- visual outcome
- posterior chamber
- lens and zonules
- vision
- treatment surgery
- child health (paediatrics)
Unilateral or bilateral paediatric cataract is a leading cause of treatable blindness.1–3 Management of childhood cataract remains a challenge. Posterior chamber (PC) intraocular lens (IOL) implantation is increasingly being used as a primary modality for management of cataracts among children with visually significant cataract.4–21 Patients with unilateral cataract and the second eye of a child with bilateral cataract should be operated on as early as possible to prevent the development of amblyopia.2–6 Phacoaspiration with posterior capsulotomy with anterior vitrectomy is usually performed in children younger than 6–8 years year.7 8 Posterior capsular opacification (PCO) is the commonest cause of decreased visual acuity (VA) after paediatric cataract surgery.2 4 5 7 12 Visually significant PCO requires surgical posterior capsulotomy with anterior vitrectomy or Nd:YAG laser capsulotomy to prevent amblyopia.9 Another notable change often seen postoperatively in growing eyes of young children is the change in refractive error.10 11 To our knowledge, this is the largest single-centre series assessing visual axis clarity, visual outcome and refractive changes after paediatric cataract surgery and IOL implantation.
Materials and methods
The records of children with congenital and developmental cataract in the age group 1 month to 15 years who underwent phacoaspiration with primary PCIOL implantation from 1999 to 2008 were retrieved. Children completing at least 1 year's follow-up were included. Approval was obtained from the Institute Ethics Committee. Children operated on for traumatic, subluxated or complicated cataract and eyes with axial length ≤16 mm were excluded from the study.
We followed a standard protocol for evaluation of children with cataract. All children underwent routine ocular evaluation including VA assessment wherever possible. The posterior segment was assessed using B-scan ultrasonography in dense cataracts. IOL power was calculated using SRK-II formula in cooperative children where keratometry was possible. In young and uncooperative children, the axial length of the eye was used for IOL power calculation using the Dahan formula.10
Preoperatively, topical antibiotic ofloxacin (0.3%) or moxifloxacin (0.5%) was instilled six times a day prior to the surgery. Mydriasis was achieved with 1% cyclopentolate and 5% phenylephrine (2.5% phenylephrine in children <2 years) instilled three times half hourly before the surgery. Informed consent was obtained from the parents/guardians. Cataract surgery was performed under general anaesthesia. A continuous curvilinear capsulorhexis (CCC) of approximately 5.0 mm was fashioned and followed by multiquadrant hydrodissection.22 After phacoaspiration, capsular bag implantation of IOL was performed. Primary posterior capsulotomy (size 3–3.5 mm) was performed with limited anterior vitrectomy in children ≤6 years. Intraocular lenses implanted were either single-piece square-edge polymethyl methacrylate (PMMA) (Aurolab SQ3602, Aravind, Madurai, India or 811C, Advanced Medical Optics, Santa Ana, California) or hydrophobic acrylic intraocular lens (Sensor Optiedge/Tecnis acrylic Abbott Medical Optics, Alcon MA60AC or Alcon SA60AT (Alcon Inc, Fort Worth, Texas, USA)) or silicone IOL (Tecnis Z9000, Abbott Medical Optics). All these IOLs have an optic diameter of 6 mm and an overall diameter of 13 mm except Aurolab SQ 3602 and 811C, which have an overall diameter of 12.5 mm and 12 mm respectively.
All children were examined on the first postoperative day, 1 week, 2 weeks, 1 month and then 3 months and 6 months. All patients with unilateral cataract were given an occlusion in the normal eye for 6 h daily. In bilateral cases, an occlusion was given in the eye with significantly better vision. Maintenance patching 2 h a day was initiated when the VA was within two lines of the better eye and was continued until the child reached 10 years of age. The primary outcome measures were visual axis clarity and refractive error changes. The secondary outcome measures were final VA achieved and evaluation of complications.
Examination for visual axis obscuration consisted of slit-lamp examination under retro-illumination wherever possible. Younger or uncooperative children were examined under anaesthesia. The posterior capsule opacification was considered visually significant if the visual axis was involved. The criteria used for the diagnosis of glaucoma included presence of sustained rise in IOP of >20 mm Hg (normal value under halothane anaesthesia is approximately 9–10 mm Hg) and any one of the following:
progressive optic disc changes suggestive of glaucomatous damage;
increase in horizontal corneal diameter;
corneal clouding;
retinoscopic myopic shift.
A diagnosis of optic capture was made when a part of the optic of the intraocular lens was entrapped in the pupil.
In young children with PCO, a membranectomy was performed through the parsplana route. In cooperative children, Nd:YAG capsulotomy of around 3.5–4 mm in diameter was performed.
Postoperatively, the refractive status of the children was assessed by retinoscopy at 2 weeks after surgery and repeated thereafter every 2–3 months. Toddlers were prescribed glasses with near add of +3.0 D added to the retinoscopy value. However, schoolchildren were given bifocals. In case of significant anisometropia (difference of 5 D or more), eyes were considered for IOL exchange or piggyback IOL. Visual acuities were converted to the logarithm of the minimum angle of resolution (logMAR) for statistical analysis.
A statistical analysis was performed using SPSS for Windows 2000, version 11.0.1 (SPSS, Chicago, Illinois). Chi-square and Mann–Whitney tests were used to compare the posterior capsulotomy rates in the three groups and logMAR VA in unilateral and bilateral cases respectively. The Wilcoxon test was used to compare the difference in refractive errors in the three age groups statistically. Significance was set at 95% CI (p≤0.05).
Results
Two hundred and thirty children (167 males and 63 females) fulfilled the inclusion criteria. Seventy-nine children had unilateral cataract and 151 bilateral cataract. The age of children at the time of surgery ranged from 1 month to 15 years with the mean being 50.59±46.46 months (median 36 months). The mean follow-up period was 31.08±22.89 months (12 to 102 months, median 36 months). The mean preoperative axial length was 20.52±2.09 mm (16.01–27.02 mm, median 20.5 mm). IOL fixation was capsular bag in 374 and sulcus–sulcus in 7 eyes.
In group A, 208 eyes were implanted with PMMA IOL. The mean age of children in group A was 51.34±46.23 months (1 month to 15 years, median 36 months). In 157 eyes of children aged ≤6 years, a primary posterior capsulotomy with anterior vitrectomy was performed, and in 51 eyes the posterior capsule was left intact (age >6 year).
In group B, 144 eyes were implanted with hydrophobic acrylic IOL. The mean age of children in this group was 50.28±49.45 months (1 month to 15 years, median 36 months). A total of 129 eyes underwent posterior capsulotomy with anterior vitrectomy (age ≤6 years), and 15 eyes (age >6 years) were left with intact PC.
In group C, 29 eyes were implanted with silicone IOL. The mean age of children in this group was 46.5±30.9 months (3 months to 9 years, median 42 months). Twenty-five eyes underwent posterior capsulotomy with anterior vitrectomy (age ≤6 years), and four eyes were left with intact PC.
In group A with PMMA IOL, visually significant visual axis obscuration (VAO) was observed in 39/208 (18.75%) eyes (figure 1). All eyes with VAO underwent a parsplana membranectomy or Nd: YAG laser capsulotomy. Visually significant PCO developed in 29 (18.47%) of 157 eyes where a primary posterior capsulotomy and anterior vitrectomy was performed and in 10 (19.60 %) of 51 eyes with intact posterior capsule. In group B with hydrophobic acrylic IOL, 21 out of 144 eyes (14.58%) developed visually significant VAO. Posterior capsule opacification developed in 18/129 (13.9%) eyes despite primary posterior capsulotomy with anterior vitrectomy and 3/15 (20%) eyes with intact PC. In group C with silicone IOL, four (16%) eyes developed visually significant VAO despite primary posterior capsulotomy and anterior vitrectomy (figure 1).
Out of 64 children developing VAO, 51 were ≤6 years, and the remaining 13 were >6 years of age. The intragroup difference in posterior capsulotomy rates between children ≤6 years and >6 years and between three IOL groups was not statistically significant (p>0.5; chi square test).
The mean refractive error at 2 weeks in children ≤2 years, >2–8 years and >8 years was +3.38±3.07 D (median +3.75 D), +0.84±3.18 D (median +1.5 D) and −0.44±1.73 D (median −0.5 D) respectively (table 1). Six eyes had refractive surprises (residual refractive error +8 D in three eyes, +7.5 D, +13 D and −8.25 D in one eye each).
The mean refractive error was +1.72 D±3.19 (median +1 D), +0.27 D±3.14 (median +0.5 D) and −0.70 D±1.77 (median −0.75 D) at 1 year and −0.51 D±3.59 (median −0.5 D), −0.62 D±2.81(median −0.75 D) and−0.89 D±1.60 (median −0.75 D) at 3 years in the age group ≤2 years, >2–8 years and >8 years respectively (table 2). The change in refractive error was highly statistically significant (p<0.0001, figure 2). Five eyes underwent intraocular lens exchange, and one eye had a piggyback-implanted IOL to achieve the desired refractive error. Patients with bilateral unexpected refraction but without anisometropia did not undergo IOL exchange.
The mean logMAR VA at last follow-up in 209 eyes was 0.4604±0.429 (median 0.3). Overall, 55.9% (117/209) of eyes had a VA of 0.3 or better. The mean logMAR VA in children with bilateral cataract was 0.4184±0.423 (median 0.3) with 62.2% of eyes with a VA of 0.3 or better. The mean logMAR VA in children with unilateral cataract was 0.6271±0.422 (median 0.6) with 30.90% of eyes having ≤0.3 (figure 3). The difference in logMAR VA between the two groups was highly statistically significant (p=0.001).
Two eyes (two children) developed glaucoma. The first child was operated on at 5 months of age and was implanted with a PMMA IOL in the sulcus; a peripheral iridectomy was not performed. The child presented at around 3 years after surgery with total synechial angle closure and underwent Ahmed Glaucoma valve implantation. In case 2, the child was operated on at the age of 4 years and had a PMMA IOL implantation in the capsular bag. The child was lost to follow-up for over 6 years and presented with total retinal detachment and neovascular glaucoma. This eye underwent diode laser cyclophotocoagulation.
Discussion
Primary PCIOL implantation has become the procedure of choice for the management of paediatric cataract.4–20 In our study, the higher male-to-female ratio (2.65:1) may be attributed to the sociocultural environment in north India where male children receive better family and medical care attention than females. Major factors affecting outcome are PCO obscuring the visual axis9 and refractive error.10 11 In this series, out of 208 eyes implanted with PMMA IOLs, significant PCO was seen in 18.75%. The capsulotomy rate was 18.47% in the children ≤6 years, despite the primary posterior capsulotomy with anterior vitrectomy and 19.6% in children >6 years with intact PC. O'Keefe et al13 reported a posterior capsulotomy rate of 40% in five eyes implanted with acrylic IOL and PPC without anterior vitrectomy. Aasuri et al14 reported visually significant PCO of 75% where PPC and anterior vitrectomy were not done. Rowe et al15 reported capsulotomy rates of 60% in patients who underwent PPC and anterior vitrectomy with PMMA intraocular lens implantation. In one of our earlier studies, we reported visually significant PCO rates of 13.3% in children with PMMA IOL where PPC with anterior vitrectomy was performed.7
Hydrophobic acrylic intraocular lenses are increasingly being used for paediatric implantation.13 14 16–18 Visually significant PCO was observed in 14.58% of eyes implanted with hydrophobic acrylic IOL. Eighteen eyes (13.9%) of 129 eyes despite PPC with anterior vitrectomy and 3/15 (20%) eyes with intact PC required membranectomy or Nd:YAG laser posterior capsulotomy. Trivedi et al16 reported PCO in 37.9% eyes in children <1 year, despite PPC and anterior vitrectomy. Aasuri et al14 reported a posterior capsulotomy rate of 17.39% in eyes implanted with acrylic IOLs (PPC and anterior vitrectomy not done). Nihalani et al17 showed that 9.1% of children <6 years implanted with AcrySof acrylic IOL who developed visually significant PCO underwent a posterior capsulotomy (only PPC was performed, and anterior vitrectomy was not done), while 14.7% of children >6 years needed posterior capsulotomy. Wilson et al reported YAG capsulotomy rates of 45.4% in children and infants implanted with AcrySof IOL and 50% in eyes implanted with PMMA IOL where PPC and anterior vitrectomy was not done.18
In our study, 29 eyes were implanted with silicone IOL, and 4/29 (13.79%) eyes developed visually significant VAO. In a study by Pavlovic et al,19 4/4 eyes without posterior capsulotomy and anterior vitrectomy developed PCO.
Five patients with anisometropia (>5 D) underwent IOL exchange, and one eye underwent piggyback IOL implantation. We found significant myopic shift in children ≤2 years compared with >2 years (Figure 2). The change in refractive error was highly statistically significant (p<0.0001; Wilcoxon test). Fan et al11 showed refractive errors on first follow-up and 3 years as +4.53±1.45 D and −2.49±3.08 in infants implanted with IOL. Dahan and Drusedau10 reported a final refraction of −0.83 D, 0.90 D and −0.40 D in children aged 1–18 months, 19–36 months and 47 months to 8 years, respectively. Nischal et al described several reasons for myopic shift in pseudophakic children.23 Age is the significant influencing factor, with younger children exhibiting a larger and more unpredictable myopic shift.10 11 24 25
The mean logMAR VA in children with bilateral cataract was 0.4184±0.423, with 62.2% of eyes having 0.3 or better (figure 2). The mean logMAR VA in children with unilateral cataract was 0.6271±0.422, with 30.90% of eyes having 0.3 or better. The difference in logMAR VA between the two groups was highly statistically significant (p=0.001). Gimbel et al20 reported a final BCVA of 20/40 or better in 79.2% of first eyes and 66.7% or better in second operated eye in bilateral cataract. In a study by Dahan and Drusedau,10 children with unilateral cataract with IOL had a mean VA of 20/60. In another study by Chak et al21 the median postoperative VA was 6/18 (range 6/5—no perception of light) in bilateral and 6/60 (range 6/5—no perception of light) in unilateral cases.
Two eyes in our series developed glaucoma (one secondary angle closure glaucoma and another neovascular glaucoma).
Trivedi et al26 reported an incidence of glaucoma of 3.8% in pseudophakic eyes and 17% in aphakic eyes. Wong et al27 reported that eyes implanted with the rigid polymethylmethacrylate group had an increased glaucoma risk compared with the AcrySof group after infant cataract extraction with and without intraocular lens implantation. The low rate of glaucoma in our study may be ascribed to a relatively short follow-up and attrition rate in our study. It may also be due to the refined surgical technique and ‘in-the-bag’ IOL implantation in almost all patients, and the fact that only pseudophakic patients were included in the study, not the aphakic one. In addition, our study included only patients with congenital cataract with no other associated ocular abnormality, and all eyes except two had an axial length greater than 17 mm at the time of surgery. The above cited reasons explain the low rate of glaucoma in our study.
Rabiah et al28 reported an incidence of 3.2% of retinal detachment in aphakic patients after paediatric cataract surgery, which was diagnosed 6.8±4.4 years postcataract surgery. In our study, seven patients had a pupillary capture of the IOL optic. Several studies reported the incidence of optic capture, ranging from 4.4% to 40% in children after paediatric cataract surgery.2 4 29
Our study is one of the large series of paediatric cataract surgery with intraocular lens implantation reporting visual axis clarity, refractive error changes and visual outcome. We found that capsular bag fixation of IOL (rigid PMMA or foldable) is safe in all age groups. The incidence of complications is low, and these are treatable, thus achieving the goal of clear visual axis and minimising the risk of amblyopia. This study adds to the previous literature on the efficacy and safety of IOLs for the correction of aphakic refractive error in children and supports the use of primary IOL implantation in any age group. We were able to reduce the visual axis obscuration in our study by performing primary posterior capsulotomy and anterior vitrectomy in children <6 years. We feel that PCO can be further reduced by performing PPC+AV up to 8 years of age. Using the Dahan formula in children 2 years or older, we observed predictable refractive results, but in children ≤2 years, the IOL power calculation based on the Dahan formula remains less accurate. The limitations of our study were that it was a retrospective review, and the duration of follow-up was short, as children particularly in the ≤3 years age group are expected to show a more myopic shift. Further prospective studies with a longer follow-up are required to study the long-term refractive change after paediatric cataract surgery with IOL implantation.
Acknowledgments
We are thankful to our Chairman, A Gupta, for his constant guidance and help.
References
Footnotes
Competing interests None.
Ethics approval Ethics approval was provided by the Institute Ethics Committee, Advanced Eye Centre, Post Graduate Institute of Medical Education and Research, Chandigarh, India.
Provenance and peer review Not commissioned; externally peer reviewed.
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