Introduction

Pediatric cataract surgery offers unique challenges when compared to adult cataract surgery. These difficulties result from differences in the surgical technique, types of complications, and prevalence.¹ Pediatric aphakia can lead to a group of problems, such as anisometropic amblyopia, posterior capsular opacification, glaucoma, strabismus, and loss of binocular function.² Due to advances in operative techniques, an increasing number of ophthalmologists have accepted primary intraocular lens (IOL) implantation as a mode of aphakic rehabilitation in recent years.^3,4,5,6 For children older than 2 years who underwent cataract surgery, IOL implantation is considered to be the gold standard by most authors.⁷ However, although IOL implantation is the standard of care for adult patients, the minimum recommended age for implantation in children remains controversial.^1,7 Because the pediatric eye is still developing, refractive changes occur during the postoperative childhood or adolescent years in patients who underwent IOL implantation for cataracts.^8,9 Moreover, varying degrees of refractive myopic shift after pediatric cataract surgery and IOL implantation have been reported, with a moderate amount of individual variability.^{4,8,9,10,11,12,13} A postoperative increased inflammatory response in children is another serious problem which can lead to fibrinous reactions, pigment deposits on the IOL, decentration of the IOL, and posterior synechiae.¹⁴

This study was designed to evaluate the postoperative outcomes, such as visual acuity improvement, refractive changes, myopic shift, complications, and additional surgical interventions, following pediatric developmental cataract surgery with primary IOL implantation.

Materials and Methods

This was a retrospective study carried out on 65 consecutive pediatric patients between 2 and 16 years of age with developmental cataracts, who underwent cataract surgery with primary IOL implantation between January 1998 and May 2014 at the Ege University Faculty of Medicine, Department of Ophthalmology. All of the patients were followed for at least 6 months postoperatively. Eyes with cataracts due to trauma, surgery, or any other ocular pathologies were excluded from this research.

Data were collected from the patients’ charts, including gender, age at time of cataract surgery, laterality, surgical procedure, best corrected visual acuity (BCVA) via Snellen chart, the presence, type, and amount of ocular deviation, cycloplegic refraction, slit-lamp examination, fundus examination and B-scan ultrasonography (if needed), IOP measurement, the course of amblyopia therapy, and postoperative complications and management. Axial length measurement (Sonogage Eye Scan, Cleveland, OH, USA) and keratometric evaluation (Topcon KR-7000P; Topcon Europe BV, Netherlands) were performed preoperatively to calculate the IOL power. Because the postoperative myopic shift was anticipated, the postoperative refraction was targeted to be hyperopic in concordance with a survey performed among the members of the American Association for Pediatric Ophthalmology.⁶ The age-adjusted target refractions were calculated as recommended by Enyedi et al.⁹. We aimed for a postoperative refractive goal of +6 for a 1-year-old, +5 for a 2-year-old, +4 for a 3-year-old, +3 for a 4-year-old, +2 for a 5-year-old, +1 for a 6-year-old, and emmetropia for older ages. The SRK/T formula was used as recommended in a recent infant aphakia treatment study.¹⁵

All of the surgeries were performed under general anesthesia by one of the authors (E.D.B., O.U., or S.K.). The operative method involved two 1.1-mm side port incisions, anterior microcapsulorrhexis, hydrodissection, phacoaspiration, an additional 3.2-mm corneal incision, and in-the-bag hydrophilic acrylic IOL implantation. If the patient was younger than 5 years old, had mental retardation, or cooperated poorly, a routine posterior capsulorrhexis combined with anterior vitrectomy was performed. In the other cases, the posterior capsule was left intact. Posterior capsulotomy combined with anterior vitrectomy was not performed in 4 children <5 years old who were cooperative enough to undergo Nd:YAG laser capsulotomy. The incisions were closed with 10-0 nylon sutures.

Prescriptions for postoperative topical tobramycin and dexamethasone sodium phosphate every two hours, and cyclopentolate hydrochloride three times each day were tapered during the first postoperative month. All of the patients were routinely examined 1 day and 5 days after surgery, then once a week for 1 month, every 1-3 months during the first year, then every 6 months during the postoperative follow-up period. The extra visits and routine follow-up visit intervals were arranged for each patient individually. Amblyopia therapy was carried out as needed. During every postoperative visit, a comprehensive ophthalmologic examination was repeated, including BCVA, refractive assessment, evaluation of ocular deviation, IOL measurement, and slit-lamp and fundus examinations.

For the analysis, the patients were divided into 3 groups according to their age at surgery: 2 to 5 years old, 5 to 8 years old, and 8 to 16 years old. All of the refractive data represented the spherical equivalent refraction (sphere plus one-half of the cylinder). Moreover, the eyes with unilateral cataracts were compared with the normal fellow eyes according to the mean refractive changes during the follow-up period.

Statistical Analysis

Statistical analysis was performed with SPSS for Windows version 18.0 (SPPS Inc., Chicago, IL, USA). All of the data were reported as the average ± standard deviation. Statistical comparisons were performed with the Mann-Whitney U and Student’s t-tests, and a p value of <0.05 was considered to be statistically significant.

The research protocol adhered to the Declaration of Helsinki for research involving human subjects. All of the parents or guardians of the children studied provided written consent to the screening and follow-up assessments.

Results

A total of 101 eyes of 65 patients were included in this study; 36 patients had bilateral cataract surgery. The average age at the time of surgery was 76±40 months (range 25-192 months) and the average follow-up time was 44±30 months (range 6-174 months). Both the pre- and postoperative visual acuities (Snellen chart) could be evaluated in 78 eyes of 52 patients. BCVA improved by ≥2 lines in 61 eyes (78.2%), and improved by 1 line in 6 eyes at the last follow-up when compared with their preoperative measurements. Six of the eyes showed no changes in visual acuity. At the last follow-up, 71 eyes of 47 patients had visual acuities of ≥0.5.

The visual acuity improvements were also analyzed according to laterality (Table 1). Among those patients who had unilateral cataract surgery, visual acuity improvement could be assessed in 26 eyes. BCVA improved by ≥2 lines in 19 eyes (73.1%) and by 1 line in 2 eyes at the last follow-up when compared with their preoperative measurements; however, 5 eyes showed no changes in visual acuity. The visual acuity improvement could be evaluated in 52 eyes of 26 patients among the 36 patients who had bilateral cataract surgery. The BCVA improved by ≥2 lines in 47 eyes (90.4%), and improved by 1 line in 4 eyes at the last follow-up when compared with preoperative measurements. One eye showed no change in visual acuity.

Ten patients had monocular sensory strabismus preoperatively. The visual acuity improvement could be assessed in 7 of the 10 patients with monocular strabismus. In 6 eyes (85.7%), BCVA improved by ≥2 lines. Three patients had nystagmus preoperatively. One of them had an improvement of ≥2 lines in both eyes. 

Among 42 children (64.6%) that were prescribed occlusion therapy after surgery, 36 could be evaluated during the follow-up period with regard to their visual acuity improvement; 18 (50%) showed ≥2 lines of improvement in response to the occlusion therapy.

The patients were divided into 3 groups according to their ages at time of surgery: 43 eyes of 25 patients 2 to 5 years old in the first group, 28 eyes of 18 patients 5 to 8 years old in the second group, and 30 eyes of 22 patients 8 to 16 years old in the third group. Refractive changes were analyzed according to these age groups (Table 2). The mean refractive change and refractive change per year of follow-up were calculated among only the cases with myopic shift. Although these values were observed to be greatest in the younger age groups, only the difference in the mean refractive change between the 2-5 years old and 8-16 years old age groups were found to be statistically significant (p=0.009). However, the mean refractive change per year was not significant between the 2-5 years old and 8-16 years old age groups (p=0.335).

In the unilateral cases, the operated eye showed a greater mean refractive change and greater mean refractive change per year. However, there was no significant difference between the operated and nonoperated eyes regarding the mean of these values (mean refractive change -1.05±1.64 vs. -0.58±0.66, mean refractive change per year -0.36±0.87 vs. -0.22±0.53; p values 0.18 and 0.48, respectively).

No intraoperative complications were observed. In 52 of 101 eyes, at least one postoperative complication was observed during the follow-up period. The most common ocular complication was visual axis opacity, which was observed in 49 eyes, including posterior capsule opacification (PCO) in 23 eyes (22.8%), secondary membrane or lens reproliferation in 15 eyes, and capsular phimosis in 11 eyes.

Posterior capsulotomy and anterior vitrectomy were performed in 67 eyes. Visual axis opacification (PCO in 11 eyes, secondary membrane or lens reproliferation in 4 eyes, and capsular phimosis in 8 eyes) was seen in 23 of those 67 eyes (34.3%) and 15 of them required additional intervention (22.3%). Among 34 eyes without primary posterior capsulotomy, visual axis opacification (PCO in 22 eyes, secondary membrane or lens reproliferation in 1 eye, and capsular phimosis in 3 eyes) was observed in 26 eyes (76.4%) and 22 of them required further intervention (64.7%) (Figure 1).

Pediatric pseudophakic glaucoma was observed in 2 eyes (1.98%), and medical antiglaucomatous treatment was effective in both cases.

Discussion

In this study, we reported good visual outcomes after cataract surgery with primary IOL implantation in pediatric patients between 2 and 16 years of age. We were able to assess the visual acuity changes after surgery in 78 eyes, and of those, 72 eyes (92.3%) showed improvements in visual acuity. In a study by Kleinman et al.¹, the authors reported that over 80% of the eyes had improvements in visual acuity, and more than 50% of the eyes achieved visual acuities of ≥20/40 at the last follow-up. In another study by Crouch et al.², out of 52 pediatric pseudophakic eyes, 85% had 20/40 vision or better. Inatomi et al.¹⁶ observed visual acuities of 20/40 or better in 79% of the operated eyes in their study of 15 unilateral cases. We observed 2 lines or more of visual acuity improvement in 78.2% of our patients, while 91% of the patients had visual acuities of 20/40 or better at the last follow-up, in concordance with the literature.

Myopic shifts following pediatric cataract surgery and IOL implantation have been reported in the literature to varying degrees.^{8,9,10,11,13,17} In our study, we found myopic shifts in all of the age groups; however, the differences in the mean refractive change and mean refractive change per year, especially in the 2-5 years old age group, were found to be much greater, which was statistically significant. Plager et al.¹⁷ reported refractive changes in 38 eyes that underwent primary IOL implantation and were followed for an average of 6 years. They stated that the rate of myopic shift decreased with age, and the variability among individuals decreased with age. Crouch et al.² observed a myopic shift that continued even until early adolescence following cataract surgery in their long-term study, with an average follow-up of 5.45 years. Although in previous reports the myopic shift in pseudophakic eyes has been attributed to excessive axial elongation by amblyopia and visual deprivation,^18,19 Enyedi et al.⁹ reported that they did not believe that the trend of myopia in pseudophakia was the result of excessive elongation, but rather of normal eye growth with a fixed IOL power. They suggested that the myopic shift that they and other authors have observed is consistent with this growth pattern.⁹ Dahan and Drusedau¹⁰ also reported that pseudophakic eyes showed the most axial elongation during the first 2 years, and continued to grow more slowly up to the age of 8 years old, as in normal phakic eyes.

In 15 unilateral cases, long-term (4 to 15 years) changes in refraction, axial length, and refractive power of the cornea were evaluated and compared with nonoperated eyes, and no significant differences in the axial length or refractive power of the cornea between the operated and nonoperated eyes were detected, although there was significant myopic change in the operated eyes.¹⁶ Enyedi and other authors (like Crouch) explained that this was because the IOL power was stable in the operated eye, while the normal phakic lens retained accommodation and compensated for developmental elongation.^2,9 In developing phakic eyes, it was reported that the progressive flattening of the crystalline lens decreased the refractive consequences of axial elongation.²⁰ McClathey et al.²¹ inferred that the myopic shift of an operated eye was an optical phenomenon; as the eye grows, the IOL moves farther and farther from the retina. Analogous to the effects of the vertex distance with high-power lenses, the anterior movement of the IOL as the child grows induces a myopic shift by itself.²¹ When we evaluated our unilateral cases and compared the operated eyes with the fellow eyes, we found a higher myopic shift in the operated eyes than the nonoperated fellow eyes, in concordance with these studies, but the difference was not statistically significant. However, since we did not measure axial length in the follow-up visits, we could not discuss how axial elongation influenced the refractive state in the pseudophakic eyes during the children’s development. This is a major limitation of our research.

Postoperative complications were another focus of our study. We determined that the most common ocular complication was visual axis opacity, including PCO, secondary membrane or lens reproliferation, and capsular phimosis, as previously reported.^1,14 The prevalence of PCO has been reported to range between 14% and 72% in different studies with different age groups, surgical techniques, and IOL types.^1,2,22 We observed PCO in 22.8% of our cases, secondary membrane or lens reproliferation in 14.9%, and capsular phimosis in 10.9%. However, all of these complications were successfully treated using appropriate interventions. The preventive measures for visual axis opacification following pediatric cataract surgery include a primary posterior capsulectomy with or without anterior vitrectomy.²³ In our clinic, we routinely perform a posterior capsulotomy with an anterior vitrectomy post-IOL implantation in children under 5 years old. In patients older than this, we leave the posterior capsule intact because, in most of those cases, it is easier to treat PCO with Nd:YAG laser. In our study, all of the eyes in patients older than 5 years with significant PCO were successfully treated with Nd:YAG laser.

Glaucoma is one of the most important and common complications of congenital cataract surgery. It is reported that the incidence of glaucoma in cases of aphakia ranges from 0.9% to 32%, which is less common than in pseudophakic patients.^24,25 In a recent study among pediatric patients, glaucoma incidence was reported as 33.3% in aphakia and 34.8% in patients with secondary IOL implantation, whereas no glaucoma was detected in patients with primary IOL implantation.²⁶ Our glaucoma incidence was 1.98%, in concordance with the literature.

Conclusion

In conclusion, this study demonstrated that good visual outcomes can be achieved after pediatric cataract surgery with IOL implantation, even in patients with monocular sensorial strabismus and nystagmus. Occlusion therapy can play a great role in the improvement of visual acuity. Refractive changes after pediatric cataract surgery are inevitable, and predicting a future myopic shift remains difficult. Physicians must be aware of the variability of refractive changes, and must adjust for this with appropriate spectacles. Surgeons should also be aware of the possible postoperative complications after pediatric cataract surgery, and must pay close attention. Careful long-term follow-up and informing parents of any possible complications are essential for the care of these patients.

Ethics

Ethics Committee Approval: Ege University, Clinical Research Ethics Committee (approval no: 17-11.1/76).

Informed Consent: The research protocol adhered to the Declaration of Helsinki for research involving human subjects. All of the parents or guardians of the children studied provided written consent to the screening and follow up assessments.

Peer-review: Externally peer-reviewed.

Authorship Contributions

Surgical and Medical Practices: Elif Demirkılınç Biler, Önder Üretmen, Süheyla Köse, Concept: Elif Demirkılınç Biler, Design: Elif Demirkılınç Biler, Önder Üretmen, Data Collection or Processing: Şeyda Yıldırım, Elif Demirkılınç Biler, Analysis or Interpretation: Elif Demirkılınç Biler, Önder Üretmen, Süheyla Köse, Literature Search: Şeyda Yıldırım, Elif Demirkılınç Biler, Writing: Elif Demirkılınç Biler, Öner Üretmen, Şeyda Yıldırım.

Conflict of Interest:No conflict of interest was declared by the authors.

Financial Disclosure:The authors declared that this study received no financial support.