Visual Outcomes of Secondary Lens Implants in Children with Different Etiologies

This study investigated visual outcomes and factors that impact vision in children receiving secondary intraocular lens (IOL) implants. including and Moreover, necessity varies according a Moreover, crucial to are noted among different

In infants, intraocular lens (IOL) implantation can be beneficial in terms of visual rehabilitation and reduce postoperative complications. However, the timing of implanting lens in children with congenital cataract must be carefully decided by considering age during surgery, postoperative complication risks, and treatment affordability of patients' families along with the selection of suitable IOL power and type. IOL can be safely and effectively implanted in infants aged ≥6 who have well-developed eyeballs and satisfactory systemic conditions. Otherwise, surgeons can opt for secondary lens implants.
Congenital cataract, which is characterized by vision loss and amblyopia formation, is a treatable cause of loss of vision in childhood [1]. Visual rehabilitation can be successful when performed when children are aged <3 months, which is considered the amblyogenic window [2]. The axial length rapidly increases until 2 to 3 years of age in healthy children [2]. Moreover, lens implantation after cataract removal can cause myopic shift in patients aged <2 years. Furthermore, these children can develop cosniderable uveal inflammation [9,10] and intensive posterior capsule opacification. Because the safety and efficacy of IOL implantation remain controversial, primary cataract removal is preferred in cases detected early. Subsequently, contact lenses or spectacles can be employed for aphakia correction combined with amblyopia management [11,12]. In the Infant Aphakia Treatment Study, no differences in visual acuities were noted between children who had unilateral cataract and received primary lens implants and those using contact lenses for surgical aphakia correction [10]. Secondary lens implantation is opted when aphakic children aged >2 years cannot tolerate wearing contact lenses or spectacles [13]. Limited studies have examined secondary IOL implantation's long-term vision outcomes. This study investigated secondary IOL implantation's long-term vision-related outcomes in children with aphakia aged >2 years and potential factors impacting visual acuity postoperatively.
Secondary lens implantation result in satisfactory outcomes in vitrectomized eyes. After vitrectomy, spectacles can be employed for correcting vision. However, the technique and timing of secondary lens implantation to correct vitrectomized aphakia remain unclear, particularly for the loss of capsule integrity and zonular dialysis. Primary lens implantation performed during initial reconstruction resulted in satisfactory outcomes in injured eyes [8][9][10][11]. However, primary lens implantation can lead to complications including synechiae, fibrinous uveitis, retinal detachment, pupillary capture, and those related to the posterior segment [14][15][16][17].

Methods
We retrospectively evaluated the medical details of children receiving secondary lens implants between 2000 and 2019. The ethical committee approved this study. To ensure the identification of eligible children, a chronological surgery list was cross-referenced by performing a database search of children receiving treatment for traumatic or nontraumatic cataract. Children who were aged between 0 and 18 years during their secondary lens implantation, which was performed by a single surgeon, were examined. Children with congenital glaucoma or retinopathy of prematurity were excluded. In addition, those with incomplete data regarding cataract removal or postimplantation follow-up were excluded. Intra-and post-operative complications and visual outcomes at the final visit were evaluated.
Information regarding sex, age during surgery, ethnicity, cataract type, laterality, corneal diameter, keratometry, axial length determined through immersion A-scanning, age during IOL implantation, IOL power and type implanted, reason for IOL implantation, and site of IOL fixation was collected. All data were exported in the online pretest format and added in an Excel sheet; all data were examined using SPSS 22. Descriptive analysis, cross tabulation, and t test were performed for statistical analyses. A P value of <0.05 was considered to be statistically significant.

Discussion
Aphakia is caused due to many factors in children. This study examined factors such as congenital cataract, openglobe ocular trauma, and congenital anomalies such as ectopia lentis unlike other studies that focused on congenital cataracts, traumatic cataracts, or ectopia lentis [3][4][5][6][7][8]. Here, we compared visual outcomes for all categories. The nontraumatic category exhibited more favorable outcomes possibly due to comorbidities in traumatic cases (p=0.004; Table ).
Secondary lens were implanted in different locations, namely the bag and sulcus; scleral-fixated and posterior chamber iris claw lens were implanted. No significant differences were observed (p=0.09). According to Wood et al., secondary lens implanted in the capsular bag resulted in fewer complications than did those in the ciliary sulcus.
Many patients recruited to this study received implants in the capsular bag (69.4%). This finding may be responsible for low complication rates and indicates that capsular bag preservation is crucial for secondary lens implantation. However, this finding limits the generalizability of study results to other centers where a higher proportion received implants in the bag and sulcus [18].
The major complication or cause of nonimprovement of vision in this study was corneal opacity (12/84 patients, 14.29%, Table). A study reported VAO, secondary glaucoma, and refractive problem as causes in 5.4%, 16.4%, and 8.1% of patients, respectively. The current study included many (32/84) posttrauma cases causing corneal opacities (  [18,19]. This might be attributed to the lack of awareness in rural areas and ignorant parents. Owing to the low socioeconomic status, compliance of aphakic spectacles and contact lenses is poor, thus affecting the outcome because of amblyopia. The mean follow-up period was 3.53 ± 5.6 years in this study, 57.6 ± 33. 6  These results are similar to those reported by previous studies [16,17] including that conducted by Nihalani and Vanderveen [14] who demonstrated that 50% eyes had a BCVA of ≥20/40 and Shenoy et al. who found that 35% eyes had a BCVA of ≥20/40 [20]. Hu et al. demonstrated that secondary iris claw lens implantation resulted in satisfactory vision [21]. Forlini indicated that retro pupillary iris claw lens is a suitable option for scleral-fixated or angle-supported lens [22]. Retropupillary iris claw lens implantation can safely and effectively correct aphakia without capsule support [23,24].
He et al indicated that secondary lens implants can safely correct aphakia in for open-globe injury patients undergoing vitrectomy. This finding is in agreement with that of this study; we noted no differences in outcomes among various lens positions [25]. Secondary sulcus IOL could be implanted after preserving the anterior lens capsule during primary implantation in children with anterior PFV; this procedure resulted in favorable vision outcomes after operation and a compatible proportion of complications [26][27][28]. Yu [29,30]. Edelstein S reported successful outcomes of scleral-fixated lens implants in congenital ectopia lentis, which is similar to this study [31]. This study compared the outcomes of various lens positions in different etiologies and exhibited no significant differences.
Strength of the present study is that the same surgeon operated all eyes. The study is limited by its retrospective nature; however, incomplete records were excluded. Future studies should include more patients and examine different postoperative complications. In addition, because young patients were enrolled, we could not perform BCVA Snellen measurements. A more standardized method for measuring visual acuity can be beneficial.

Conclusion
Secondary lens implantation significantly improved vision in aphakic children. Young patients and those with nontraumatic cataracts demonstrated more favorable visual outcomes