|Year : 2016 | Volume
| Issue : 2 | Page : 54-59
Primary versus secondary intraocular lens implantation in the management of congenital cataract
Thanaa H Mohamed, Rania G Eldin Zaki, Mohamed H Hashem
Ophthalmology Department, Ain Shams University, Cairo, Egypt
|Date of Submission||05-Dec-2015|
|Date of Acceptance||10-Feb-2016|
|Date of Web Publication||4-Nov-2016|
Rania G Eldin Zaki
17 Soliman Azmy Street, Heliopolis, Cairo, 11511
Source of Support: None, Conflict of Interest: None
This study aimed to compare the efficacy of primary intraocular lens (IOL) implantation following removal of congenital cataract in patients with aphakia younger than 2 years of age, followed by secondary implantation after the age of 2 years.
Patients and methods
This was a comparative prospective study that included patients with congenital cataract (28 eyes) who underwent lensectomy and anterior vitrectomy in the first year of life; 14 eyes were subjected to primary IOL implantation. Fourteen eyes with left aphakia were subjected to visual rehabilitation until the age of 2 years. Secondary implantation was performed and the two groups were followed for 2 years after implantation by a full ophthalmological examination.
Postoperative significant uveitis occurred in 14.2% of patients in group A and 35.7% of patients in group B; the difference between the two groups was statistically insignificant. Fixation was good in 71% of patients in group A and in 57% of patients in group B; this difference was nonsignificant. Increasing intraocular pressure was noted in four cases in group B that was statistically significant and the diagnosis of glaucoma was confirmed and managed, whereas in group A, none of the cases had an intraocular pressure higher than 18 mmHg.
Primary IOL implantation was found to be safe and effective in the management of congenital cataract; it leads to lower incidence of complications and better visual outcomes compared with aphakia and secondary IOL implantation.
Keywords: aphakia, intraocular lens implantation, intraocular pressure, significant uveitis
|How to cite this article:|
Mohamed TH, Eldin Zaki RG, Hashem MH. Primary versus secondary intraocular lens implantation in the management of congenital cataract. J Egypt Ophthalmol Soc 2016;109:54-9
|How to cite this URL:|
Mohamed TH, Eldin Zaki RG, Hashem MH. Primary versus secondary intraocular lens implantation in the management of congenital cataract. J Egypt Ophthalmol Soc [serial online] 2016 [cited 2019 Jul 19];109:54-9. Available from: http://www.jeos.eg.net/text.asp?2016/109/2/54/193401
| Introduction|| |
Cataract surgery with intraocular lens (IOL) implantation in children has witnessed marked changes during the last three decades, largely as a result of advances in technological and microsurgical techniques . However, postoperative complications associated with pediatric cataract-IOL surgery continue to be a major concern. The risk of postoperative complications is higher because of the greater inflammatory response after pediatric intraocular surgery. Although amblyopia from delayed treatment remains the most common cause of a poor visual outcome, these complications are the primary reason for poor vision in many cases . In some cases, the complications appear to be intrinsically related to associated ocular anomalies that coexist with the developmental cataract. Close follow-up and early detection and management of the complications are mandatory .
The surgical indications and techniques for congenital cataract are well established. However, controversy on the method of correction of the resulting aphakia remains, with the method depending on the age of the child at the time of surgery . A number of factors may influence the surgical outcomes including patient age; type of cataract; laterality; timing of surgery; technical surgical aspects; changing refraction; functional outcome and amblyopia; choice of aphakia correction and IOL implantation; the active lens epithelial cells and resultant posterior capsular opacification (PCO); the presence of thick vitreous in the pediatric age group, which protects against cystoid macular edema; and finally, parental care and compliance .
Surgery for congenital visually significant cataract must be performed as early as possible to prevent irreversible amblyopia and the timing of surgery needs to balance the effect on visual development and the surgical risks . Recently, refined surgical techniques and options for optical correction of aphakia improved both the technical and the functional outcomes of pediatric cataract surgery. Optical correction includes aphakic glasses, contact lenses, and primary IOL implantation. Each of the options has its own advantages and disadvantages .
The capability of the IOL to provide a constant visual stimulus led to the acceptance of IOL implantation as an alternate form of optical correction. Despite controversies, IOL implantation is being performed in infants with increasing frequency .
In this study, we compared the functional results in children who were subjected to early (before 12 months old) IOL implantation with patients who had primary aphakia, followed by secondary implantation (after the age of 2 years). The goal was to determine the best timing of IOL implantation for correction of aphakia in children with congenital cataract by comparing the visual outcomes and complications such as glaucoma, uveitis, membrane formation, synechia, and secondary interventions.
| Patients and methods|| |
A comparative prospective nonrandomized study was carried out at the Ophthalmology Department. After receiving approval from the ethical committee, children under 1 year of age (28 eyes) were operated upon for significant congenital cataract; they were divided into two groups: group A (14 eyes) was subjected to lensectomy with primary IOL implantation of a three-piece foldable hydrophobic acrylic IOL in the bag and group B (14 eyes) was subjected to the same procedure without IOL implantation with postoperative visual rehabilitation by extended wear contact lenses until the age of 2 years. Then, secondary implantation of a three-piece foldable hydrophobic acrylic IOL in the bag was performed. Following IOL implantation, all patients were followed up for 2 years.
- Significant congenital cataract bilateral and unilateral cases.
- Normal corneal diameter.
- Normal intraocular tension.
- No squint or nystagmus at presentation.
- Micro cornea.
- Micro ophthalmia or other ocular abnormalities.
- Large corneal diameter at presentation.
- Anterior or posterior synechia.
- Elevated intraocular pressure (IOP) more than 20 mmHg.
- Optic disc cup–disc ratio more than 0.4 or a more than 0.2 difference between the two eyes.
- Poor fixation.
- Squint or nystagmus at presentation.
All patients were subjected to a preoperative full ophthalmic examination under general anesthesia with pupillary dilatation, anterior segment evaluation, horizontal corneal diameter, and intraocular tension measurement with a handheld applanation tonometer (Kowa applanation tonometer HA-2; Japan); fundus examination if seen by indirect ophthalmoscopy and B scan ultrasound were performed in patients with dense cataract.
Holladay II formula was used to calculate the IOL power  then the target post operative refraction was determined according to child age, under 1 year of age to be +4 D hypermetropia, up to 2 years of age to be +3.5 D, from 3 to 5 years old to be +2.5 D .
Group A was subjected to lensectomy, posterior capsulorrhexis, and anterior vitrectomy with peripheral iridectomy through the limbus with implantation of a three-piece foldable hydrophobic acrylic IOL in the bag at the time of cataract extraction. Group B was subjected to the same procedure without IOL implantation with postoperative visual correction by wearing of contact lenses for an extended period of time for both unilateral cases and bilateral cases until the age of 2 years. Then, secondary implantation of a three-piece foldable hydrophobic acrylic IOL in the bag was performed. Following secondary implantation, all patients were followed up for 2 years.
Topical steroids were used as frequently as 10–12 times a day during the first postoperative week and tapered over a period of 6 weeks to decrease the incidence of uveitis. Topical antibiotics were instilled three times a day for 10–14 days. Cyclopentolate eye drops 0.5% or atropine eye ointment had to be used for about 4 weeks to prevent posterior synechia formation.
Postoperative follow-up was performed after 1 week, every 3 months in the first year, and then every 6 months in the second year. At each visit, a full ophthalmic examination was performed, child fixation and examination of any degree of squint. The assessment was performed binocularly and then monocularly by drawing the child’s attention to a handheld toy. Resistance to occlusion of the child eye is useful to judge the relative vision in each eye. Fixation behavior is recorded for each eye as ‘fixates, follows, maintain.’ Ocular alignment is assessed using the corneal light reflection and the cover test. Objective refraction was assessed under general anesthesia until the age of 2 years in the patients in group A and until the age of 4 years in the patients in group B. Examination of both anterior and posterior ocular segments, corneal diameter, and IOP measurement were performed. The diagnosis of glaucoma was confirmed by repeated measurements of corneal diameter and increasing IOP; any reaction in the anterior chamber was recorded following IOL implantation in both groups and any IOL decentration or pupillary capture was also recorded.
Visual correction for aphakia for the patients in group B was performed by wearing of contact lenses for an extended period of time for both unilateral cases and bilateral cases until secondary IOL implantation was performed.
Residual refractive error resulting from targeted postoperative hypermetropia after secondary implantation was fixed by wearing of contact lens for an extended period of time for unilateral cases and by wearing of spectacles for bilateral cases.
All data were collected and analyzed statistically using SPSS for windows, version 13.0 (SPSS Inc., Chicago, Illinois, USA). Qualitative data were expressed as number and percentage; a comparison was carried out using the χ2-test. Quantitative data were expressed as mean and SD. An independent t-test was used for the comparison of quantitative variables between two groups. The significance of the data was determined by the probability. P greater than 0.05 was considered insignificant, P less than or equal to 0.05 was considered significant, and P less than or equal to 0.01 was considered highly significant.
| Results|| |
Group A included patients with an average age at surgery of 4.11±1.86 months (14 eyes), whereas group B included patients with an average age at primary surgery of 4.96±1.5 months (14 eyes); then, secondary implantation was performed at the age of 2 years. There was no statistically significant difference between the groups in terms of sex; four cases in the first group were subjected to bilateral primary implantation and five patients in group B were subjected to bilateral secondary implantation [Table 1].
Postoperative significant uveitis after primary IOL implantation occurred in group A and after secondary IOL implantation in group B in the form of a fibrinous reaction in two cases (14.2%) in group A and in five cases in group B (35.7%); the difference between the two groups was statistically insignificant using the χ2-test [Table 2].
|Table 2: Comparison between groups A and B in the incidence of significant uveitis after IOL implantation|
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In terms of vision improvement after implantation of IOL, fixation by the operated eye was diagnosed as good if the child could fix on and follow an object by the eye and resist occlusion; if not, the fixation was diagnosed as poor. By the end of 2 years of follow-up in both groups, in group A, fixation was good in 71.43% of patients whereas in group B, fixation was good in 57.14% of patients; this difference was nonsignificant (P=0.127) [Table 3].
|Table 3: Comparison between groups A and B as in fixation after IOL implantation|
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All patients with poor fixation of the operated eye in group A were unilateral cases (66.7% of unilateral cases), with absence of poor fixation of the operated eye in bilateral cases. In group B, all unilateral cases had poor fixation in the operated eye (100% of unilateral cases), whereas in group B, poor fixation of the operated eye was observed in only 20% of bilateral cases. There was a statistically significant difference between the two groups in postoperative fixation (P=0.015) [Table 4].
|Table 4: Comparison between groups A and B in fixation after IOL implantation in unilateral and bilateral cases in both groups|
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Increasing IOP was noted in four cases in group B (28.6%) that was statistically significant; the diagnosis of glaucoma was confirmed and IOP was controlled by submacular surgery trials surgery for these cases in this group, whereas in group A, none of the cases had IOP higher than 18 mmHg during all follow-up visits. The average age of the patients at diagnosis of glaucoma was 16±3.4 months postoperatively after IOL implantation and the average IOP at the time of glaucoma surgery was 28±2 mmHg.
The differences between the mean IOP measurements in groups A and B were only significant preoperatively (before primary implantation in group A and in aphakic patients before secondary implantation in group B), P value 0.009, whereas at all follow-up postoperative visits after IOL implantation, the mean IOP between the two groups was insignificant using an independent sample t-test, with a P value less than 0.05 considered significant [Table 5].
|Table 5: Comparison between groups A and B in the average IOP before IOL implantation and at all follow-up visits after IOL implantation|
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[Figure 1] shows the bar chart between primary and secondary implantation of IOL in terms of IOP preoperatively to IOL implantation and all follow-up visits after IOL implantation every 3 months in the first year and every 6 months in the second year of follow-up.
|Figure 1: Bar chart of groups A and B showing the mean IOP before IOL implantation and during follow-up visits after IOL implantation. IOL, intraocular lens; IOP, intraocular pressure.|
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| Discussion|| |
The incidence of glaucoma following pediatric cataract surgery varies from 3 to 41% . Glaucoma that develops soon after surgery is usually because of pupillary block or peripheral anterior synechia formation, whereas open-angle glaucoma may occur late, which emphasizes the need for life-long follow-up of these children . A peripheral iridectomy may prevent pupillary block in pseudophakic glaucoma. IOP should be recorded periodically to detect and treat this vision-threatening complication ,.
In this study, none of the patients who had been subjected to primary IOL implantation in group A developed glaucoma, whereas four patients in group B developed glaucoma following secondary IOL implantation. Open-angle glaucoma was observed in these patients that could not be treated medically; surgical treatment was required to lower IOP. Glaucoma was diagnosed on the basis of the following criteria: IOP more than 22 mmHg using a handheld applanation tonometer, optic nerve cup–disc ratio more than 0.4 or a more than 0.2 difference between the two eyes, and corneal diameter more than 12 mm. One patient had an IOP of 26 mmHg after 1 year of secondary implantation, two patients had IOP of 28 and 30 mmHg 1.5 years after IOL implantation, the fourth patient had an IOP of 32 mmHg after 2 years. Glaucoma occurred up to 2 years following secondary implantation, which emphasizes the importance of long-term follow-up in these patients, and the importance of primary implantation of IOL in preventing an increase in IOP was evident. These four patients of group B with uncontrolled IOP underwent a subscleral trabeculectomy operation to control IOP. After the procedure, the IOP of the operated eyes returned to normal.
Comparable primary data from Asrani and Wilensky  reported a decreased incidence of open-angle glaucoma in eyes that were primarily pseudophakic compared with those that remained aphakic after cataract surgery; they found that only one patient developed glaucoma among 377 eyes with primary pseudophakia (mean age of the patient 5.1±4.7 years; mean follow-up duration 3.9±2.7 years). A total of 14 eyes (11.3%) out of 124 aphakic eyes developed glaucoma (mean age of the patient 2.7±2.6 years; mean follow-up duration 7.2±3.9 years). IOL implantation was commonly performed in eyes with a corneal diameter more than 10 mm.
Carter et al.  also reported that the incidence of aphakic glaucoma has been reported to be as high as 41%, with an onset of disease averaging from 3.1 to 6.8 years after lensectomy. Patients presenting with nuclear cataracts or persistent fetal vasculature have been noted to have an increased frequency of development of postoperative glaucoma, but this association is likely more closely linked to the associated microphthalmos.
The data reported above are consistent with the data of our study, suggesting that early primary implantation may have the advantage of resulting in a lower incidence of glaucoma in the pediatric age group.
Postoperative significant uveitis (fibrinous or exudative) is a common complication because of increased tissue reactivity in children . In this study, as a result of use of microsurgical techniques, closed-chamber surgery, use of hydrophobic acrylic IOL, inclusion of posterior capsulorrhexis with anterior vitrectomy as a step in the surgery to avoid the need for another intervention for PCO, and frequent use of topical steroids over a period of 6 weeks, lower incidence of significant uveitis was noted in group A (14.29%); repeated intraocular surgery may play a role in the increased incidence of uveitis in group B (35.71%) as the IOL material was the same in both groups. Uveitis was diagnosed in the form of anterior uveitis with a fibrinous reaction of the anterior chamber. Topical steroid eye drops were used as frequently as 10–12 times a day in the first week and tapered over a period of 6 weeks to control uveitis. Cyclopentolate eye drops 0.5% was used for about 4 weeks to prevent posterior synechiae formation and systemic oral steroid (dexamethasone 0.5 mg) 2.5 ml three times per day for 1 week and then tapered over 1 week.
The main problem with primary implantation was IOL power calculation in terms of the expected growth rate of the eye; the small size and changing power of the pediatric eye make it difficult to calculate the required IOL power. Formulae for IOL power in small pediatric eyes may be not very accurate . During the first weeks and months of life, keratometry changes rapidly over several diopters . Therefore, an arbitrary K-value may be most useful if an IOL is to be implanted in these very young infants. Many authors have reported an age-dependent myopic shift in children with IOL implants . However, others suggest that pseudophakic patients show less myopic shift than aphakic patients . SRK, SRKII, SRKT, Hoffer Q, and Holladay formulae have all been used successfully in children. Many authors suggest that in children younger than 6 years of age, the IOL power should be chosen to provide for some degree of hypermetropia on the basis of the expected myopic shift for that child’s age ,. Correction with spectacles or contact lenses can be performed and then adjusted appropriately to compensate for the myopic shift over the ensuing years . Others suggest that IOL power should be chosen for emmetropia to facilitate immediate amblyopia therapy . Trivedi and colleagues studied the accuracy of Holladay II formula in the absence of preoperative refraction in 45 eyes (mean age 3.9±2.9 years; range 0.1–10.4 years). They compared the predicted error in the Holladay II formula with Hoffer Q, Holladay I, and the SRK T formulas. The Holladay II formula (without preoperative refraction) yielded the least predicted error of the four formulas, followed by the Hoffer Q formula, especially in eyes shorter than 22 mm .
In this study, we chose to use the Holladay II formula, followed by calculation of postoperative target refraction for the children 1 year of age to be +4 D hypermetropia, 2 years +3.5 D, 3–5 years +2.5 D making the child hypermetrope to compensate for IOL power changes, and postoperative immediate correction of residual refractive error by glasses or contact lenses together with occlusion therapy, if needed, to treat amblyopia. Posterior capsulorrhexis and anterior vitrectomy were performed for all patients to avoid PCO; if this occurred, surgical intervention was required to avoid visual axis opacification.
In group A, four patients had poor fixation in the operated eye; all were unilateral cases, with no cases of poor fixation in bilateral cases, which could be attributed to amblyopia or negligent use of a method to correct postoperative residual error. However, in group B, six patients had poor fixation. In group B, all unilateral cases had poor fixation in the operated eye, which was also attributed to amblyopia or negligent use of a method to correct postoperative residual error, and only 20% of bilateral cases showed poor fixation, mostly caused by uveitis or development of glaucoma or amblyopia. Poor fixation was managed by correction of any residual refractive error and occlusion therapy.
Autrata et al.  reported that children treated during their first year of life for unilateral congenital cataract showed improved visual outcomes with primary IOL implantation compared with infants with contact lenses. He suggested that this is because IOLs enable full-time correction of an aphakic eye with optics that closely simulate those of a crystalline lens. Primary IOL implantation provides a stable retinal image with minimal aniseikonia and offers a permanent method of optical correction.
| Conclusion|| |
This study recommends that primary implantation is safe and effective in cases of congenital cataract as it leads to better visual outcomes and lower incidence of postoperative glaucoma and uveitis. The incidence of glaucoma increases each year after primary surgery without IOL implantation; also, the incidences of uveitis and poor fixation were higher after secondary IOL implantation. Long-term glaucoma surveillance, starting immediately after an operation, is mandatory. Recommended frequent follow-up visits including anterior segment examination using a handheld slit lamp, IOP measurement, and fundus examination, particularly during the first 4 months after surgery, are also mandatory.
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Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]