In-the-bag intraocular lens placement via secondary capsulorhexis with radiofrequency diathermy in pediatric aphakic eyes

Reopening the capsular bag by removing the capsular proliferative membrane to enable secondary in-the-bag intraocular lens implantation in pediatric aphakic eyes

PURPOSE

To present a surgical technique for reopening the capsular bag in pediatric aphakia.

SETTING

Zhongshan Ophthalmic Center, Guangzhou, China.

DESIGN

Case series study.

METHODS

Consecutive pediatric patients with bilateral aphakia requiring secondary intraocular lens (IOL) implantation between July 2021 and June 2022 were included. The diameter of the capsular proliferative membranous ring (PMR) and position of IOL implantation were documented. Various parameters of capsular bag opening during primary cataract removal and secondary surgery were also analyzed.

RESULTS

48 eyes were included with a mean follow-up of 8.1 ± 4.4 months. Using the surgical technique developed in this study, the capsular bag was successfully reopened with in-the-bag (ITB) implantation in 43 eyes (89.6%). ITB implantation was accomplished in all eyes with an outer diameter of PMR ≤5.5 mm and in 3 of 8 eyes (37.5%) with an outer diameter of PMR >5.5 mm. A positive correlation was observed between the primary and secondary anterior capsular opening diameters (ACODs) ( r = 0.422, P = .007) and the primary and secondary posterior capsular opening diameters (PCODs) ( r = 0.619, P < .001). The inner diameter of PMR was found to be positively correlated with secondary PCOD ( r = 0.728, P < .001) and the outer diameter with secondary ACOD ( r = 0.669, P < .001).

CONCLUSIONS

This was a safe and effective surgical technique for pediatric secondary IOL implantation with maximum preservation of the peripheral capsule. Aphakic eyes with an outer diameter of PMR ≤5.5 mm are preferred for secondary ITB implantation.

Safety and efficacy in pediatric secondary intraocular lens implantation, in-the-bag versus sulcus implantation: a multicenter, single-blinded randomized controlled trial

BACKGROUND

Treatment of pediatric cataract remains challenging because of the extremely high incidence of postoperative adverse events (AEs), especially the AEs related to the locations of secondary implanted intraocular lens (IOL). There are two common locations for secondary IOL implantation in pediatric aphakic eyes: ciliary sulcus or in-the-bag implantation. However, there are currently no large, prospective studies comparing complication rates and visual prognosis of in-the-bag versus ciliarysulcus secondary IOL implantation in pediatric patients. Whether or how much secondary in-the-bag IOL implantation benefits the pediatric patients more than sulcus implantation and deserves to be performed routinely by surgeons remains to be elucidated. Here, we describe the protocol of a randomized controlled trial (RCT) designed to evaluate the safety and efficacy of two approaches of IOL implantation in pediatric aphakia.

METHODS

The study is a multicenter, single-blinded RCT with 10 years of follow-up. Overall, a minimum of 286 eyes (approximately 228 participants assuming 75% have two study eyes) will be recruited. This study will be carried out in four eye clinics across China. Consecutive eligible patients are randomized to undergo either secondary in-the-bag IOL implantation or secondary sulcus IOL implantation. Participants with two eyes eligible will receive the same treatment. The primary outcomes are IOL decentration and the incidence of glaucoma-related AEs. The secondary outcomes include the incidence of other AEs, IOL tilt, visual acuity, and ocular refractive power. Analysis of the primary and secondary outcomes is to be based on the intention-to-treat and per-protocol analysis. Statistical analyses will include the χ² test or Fisher's exact test for the primary outcome, mixed model and generalized estimated equation (GEE) model for the secondary outcome, Kaplan-Meier survival curves for the cumulative probability of glaucoma-related AEs over time in each group.

DISCUSSION

To the best of our knowledge, this study is the first RCT to evaluate the safety and efficacy of secondary IOL implantation in pediatric aphakia. The results will provide high-quality evidence for the clinical guidelines for the treatment of pediatric aphakia.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05136950. Registered on 1 November 2021.

In-the-Bag Versus Ciliary Sulcus Secondary Intraocular Lens Implantation for Pediatric Aphakia: A Prospective Comparative Study

PURPOSE

To compare outcomes of in-the-bag vs ciliary sulcus secondary intraocular lens (IOL) implantation for pediatric aphakia.

DESIGN

Prospective interventional case series.

METHODS

This institutional study was conducted in 202 children (355 aphakic eyes) diagnosed as having congenital cataracts and who underwent cataract extraction before age 24 months. Pediatric aphakic eyes underwent in-the-bag or ciliary sulcus secondary IOL implantation according to the amount of residual lens capsule and were monitored for 3 years postoperatively. The main outcome measures were adverse events (AEs), IOL tilt and decentration, and best corrected visual acuity (BCVA) in the operative eye.

RESULTS

A total of 144 eyes (40.6%, 89 children) received in-the-bag IOL implantation (capsular group), and 211 eyes (59.4%, 132 children) underwent ciliary sulcus IOL implantation (sulcus group). Kaplan-Meier curves showed that the time-dependent incidence of glaucoma-related AEs (GRAEs) (P = .005) and any AEs (P = .002) were higher in the sulcus group. In-the-bag IOL implantation was a strong protective factor against GRAE (hazard ratio, 0.08; 95% CI, 0.01-0.53; P = .009) and any AEs (hazard ratio, 0.21; 95% CI, 0.08-0.57; P = .002). Clinically significant IOL decentration (>0.4 mm) was more common in the sulcus group compared with the capsular group (vertical decentration: 29.8% vs 15.7%, P = .005; horizontal decentration: 30.3% vs 9.35%, P < .001). BCVA in the capsular group was better than that in the sulcus group (logMAR, 0.56 vs 0.67, P = .014).

CONCLUSIONS

Compared with ciliary sulcus secondary IOL implantation, in-the-bag IOL implantation reduced AEs and yielded better IOL centration and BCVA for pediatric aphakia.

Microperipheral Iridectomy for Troublesome Posterior Synechiolysis in Secondary Intraocular Lens Implantation

Purpose

To introduce an effective method for separating extensive posterior synechiae and those located under or adjacent to surgical incisions.

Methods

Pediatric patients who had been subjected to cataract surgery and developed troublesome posterior synechiae requiring secondary intraocular lens (IOL) implantation were recruited. All patients underwent microperipheral iridectomy at the 12 o'clock position. Then, an ophthalmic viscosurgical device was injected into the posterior chamber through the iris fistula to mechanically separate the posterior synechiae, using scissors to cut robust posterior synechiae if necessary. The results of posterior synechiolysis and the position of the implanted IOL were analyzed.

Results

Sixteen patients (median age, 51.56 months; range, 28–80 months) were included. The scope of posterior synechia in clock was 4.42 (range, 1–10). All troublesome posterior synechiae were successfully separated using the microperipheral iridectomy method, and all patients underwent IOL implantation in the ciliary sulcus. There was one case of peripheral iridectomy-related early intraoperative bleeding; no bleeding was observed at the end of surgery.

Conclusions

Microperipheral iridectomy is a useful method for the management of troublesome posterior synechiae during secondary IOL implantation in pediatric patients, which makes secondary IOL implantation an easier and safer method in some challenging cases.

Lens regeneration in humans: using regenerative potential for tissue repairing

The crystalline lens is an important optic element in human eyes. It is transparent and biconvex, refracting light and accommodating to form a clear retinal image. The lens originates from the embryonic ectoderm. The epithelial cells at the lens equator proliferate, elongate and differentiate into highly aligned lens fiber cells, which are the structural basis for maintaining the transparency of the lens. Cataract refers to the opacity of the lens. Currently, the treatment of cataract is to remove the opaque lens and implant an intraocular lens (IOL). This strategy is inappropriate for children younger than 2 years, because a developing eyeball is prone to have severe complications such as inflammatory proliferation and secondary glaucoma. On the other hand, the absence of the crystalline lens greatly affects visual function rehabilitation. The researchers found that mammalian lenses possess regenerative potential. We identified lens stem cells through linear tracking experiments and designed a minimally invasive lens-content removal surgery (MILS) to remove the opaque lens material while preserving the lens capsule, stem cells and microenvironment. In infants with congenital cataract, functional lens regeneration in situ can be observed after MILS, and the prognosis of visual function is better than that of traditional surgery. Because of insufficient regenerative ability in humans, the morphology and volume of the regenerated lens cannot reach the level of a normal lens. The activation, proliferation and differentiation of lens stem cells and the alignment of lens fibers are regulated by epigenetic factors, growth factors, transcription factors, immune system and other signals and their interactions. The construction of appropriate microenvironment can accelerate lens regeneration and improve its morphology. The therapeutic concept of MILS combined with microenvironment manipulation to activate endogenous stem cells for functional regeneration of organs in situ can be extended to other tissues and organs with strong self-renewal and repair ability.

Techniques of anterior capsulotomy in cataract surgery

Optimal outcomes of a cataract surgery largely depend on the successful performance of an anterior capsulotomy. It is one of the most important steps of modern cataract surgery which reduces the risk of capsular tears and ensures postoperative stable intraocular lens (IOL). Anterior capsulotomy is considered ideal if it is round, continuous, well-centered, and overlaps the implanted IOL around its circumference. If any of these features is missing, it can be a cause of impedance for desired surgical and visual outcomes. Manual can opener and manual capsulorhexis are the routine standard techniques employed for manual extracapsular cataract extraction and phacoemulsification, respectively. Recent increasing use of femtosecond laser cataract surgery has allowed cataract surgeons to obviate inherent inaccuracies of manual anterior capsulotomy techniques. There is an ongoing quest to find an ideal, risk free, and surgeon-friendly technique of anterior capsulotomy that can be employed for surgery in all types of cataracts.

Screening, genetics, risk factors, and treatment of neonatal cataracts

Neonatal cataracts remain the most common cause of visual loss in children worldwide and have diverse, often unknown, etiologies. This review summarizes current knowledge about the detection, treatment, genetics, risk factors, and molecular mechanisms of congenital cataracts. We emphasize significant progress and topics requiring further study in both clinical cataract therapy and basic lens research. Advances in genetic screening and surgical technologies have improved the diagnosis, management, and visual outcomes of affected children. For example, mutations in lens crystallins and membrane/cytoskeletal components that commonly underlie genetically inherited cataracts are now known. However, many questions still remain regarding the causes, progression, and pathology of neonatal cataracts. Further investigations are also required to improve diagnostic criteria for determining the timing of appropriate interventions, such as the implantation of intraocular lenses and postoperative management strategies, to ensure safety and predictable visual outcomes for children. Birth Defects Research 109:734-743, 2017. © 2017 Wiley Periodicals, Inc.

Interocular anatomical and visual functional differences in pediatric patients with unilateral cataracts

Background

Congenital cataracts are often complicated by anterior segment dysgenesis. This study aims to compare bilateral anterior segment parameters, macular thickness, and best-corrected visual acuity (BCVA) in pediatric cataract patients at 3 months after unilateral cataract extraction with intraocular lens implantation.

Methods

Fifty-three pediatric patients with uncomplicated unilateral total cataracts were included. At 3 months post-surgery, bilateral corneal thickness at the thinnest location (CTTL), anterior chamber depth (ACD), and anterior chamber volume (ACV) were measured using Pentacam. Central macular thickness (CMT) was evaluated using spectral-domain optical coherence tomography. BCVA was measured by experienced optometrists concurrently. Descriptive statistics and bivariate corrections were performed to analyze the interocular differences in bilateral anatomic parameters and their relationships with BCVA.

Results

For all 53 included patients (mean age 5.2 ± 2.3 years), the median BCVA was 10/40 in the operated eyes and 40/40 in the contralateral eyes, which indicates a significant interocular difference. BCVA values in the contralateral eyes were significantly correlated with patient age at surgery, but this result differed for BCVA in the operated eyes. The Pentacam analysis revealed no significant interocular differences in bilateral CTTL and ACV, but significant differences were found for ACD.

Conclusions

At 3 months after surgery, unilateral pediatric cataract patients exhibited no significant interocular differences in identified anatomical parameters (except for ACD), and these parameters were not significantly correlated with BCVA in bilateral eyes. Therefore, amblyopia, but not anatomical factors, might be the main cause of interocular visual functional differences in our study population.

Trial registration

ClinicalTrial.gov, NCT02765230, 05/05/2016, retrospectively registered.

Electronic supplementary material

The online version of this article (doi:10.1186/s12886-016-0371-5) contains supplementary material, which is available to authorized users.

Capsular Outcomes After Pediatric Cataract Surgery Without Intraocular Lens Implantation: Qualitative Classification and Quantitative Measurement

The objective of this study was to investigate capsular outcomes 12 months after pediatric cataract surgery without intraocular lens implantation via qualitative classification and quantitative measurement.This study is a cross-sectional study that was approved by the institutional review board of Zhongshan Ophthalmic Center of Sun Yat-sen University in Guangzhou, China.Digital coaxial retro-illumination photographs of 329 aphakic pediatric eyes were obtained 12 months after pediatric cataract surgery without intraocular lens implantation. Capsule digital coaxial retro-illumination photographs were divided as follows: anterior capsule opening area (ACOA), posterior capsule opening area (PCOA), and posterior capsule opening opacity (PCOO). Capsular outcomes were qualitatively classified into 3 types based on the PCOO: Type I-capsule with mild opacification but no invasion into the capsule opening; Type II-capsule with moderate opacification accompanied by contraction of the ACOA and invasion to the occluding part of the PCOA; and Type III-capsule with severe opacification accompanied by total occlusion of the PCOA. Software was developed to quantitatively measure the ACOA, PCOA, and PCOO using standardized DCRPs. The relationships between the accurate intraoperative anterior and posterior capsulorhexis sizes and the qualitative capsular types were statistically analyzed.The DCRPs of 315 aphakic eyes (95.8%) of 191 children were included. Capsular outcomes were classified into 3 types: Type I-120 eyes (38.1%); Type II-157 eyes (49.8%); Type III-38 eyes (12.1%). The scores of the capsular outcomes were negatively correlated with intraoperative anterior capsulorhexis size (R = -0.572, P < 0.001), but no significant correlation with intraoperative posterior capsulorhexis size (R = -0.16, P = 0.122) was observed. The ACOA significantly decreased from Type I to Type II to Type III, the PCOA increased in size from Type I to Type II, and the PCOO increased from Type II to Type III (all P < 0.05).Capsular outcomes after pediatric cataract surgery can be qualitatively classified and quantitatively measured by acquisition, division, definition, and user-friendly software analyses of high-quality digital coaxial retro-illumination photographs.

Capsular Outcomes Differ with Capsulorhexis Sizes after Pediatric Cataract Surgery: A Randomized Controlled Trial

Capsular outcomes of anterior/posterior capsulorhexis opening (ACO/PCO) are essential for performing a secondary in-the-bag intraocular lens implantation. To compare the capsular outcomes with different primary capsulorhexis sizes, Thirty-eight eligible patients (45 eyes) were randomly assigned to three groups by anterior capsulorhexis diameter (Group A: 3.0-3.9, Group B: 4.0-5.0, and Group C: 5.1-6.0 mm). The areas of ACO/PCO and posterior capsule opening opacity (PCOO) as primary outcomes, while, the incidence of visual axis opacity (VAO) as secondary outcome were measured at follow-up visits. Among the thirty eyes included in the final analysis, the mean area of the ACO decreased significantly, whereas the PCO enlarged with time. Group A had the highest anterior capsule constriction and percentage reduction, which increased with time. There were significant differences in the percentage reductions at 6 months and 1 year compared to 1 month in Group A and B. Group C had the highest posterior capsule enlargement. The percentage of PCOO to PCO area and the incidence of VAO was highest in Group A and lowest in Group C. Thus, Capsulorhexis diameter of 4.0-5.0 mm may yield better capsular outcomes, considering moderate contraction of ACO, moderate enlargement of PCO, and lower percentage of PCOO and VAO.

Congenital cataract: prevalence and surgery age at Zhongshan Ophthalmic Center (ZOC)

Congenital cataract (CC) is the primary cause of treatable childhood blindness. Population-based assessments of prevalence and surgery age of CC, which are critical for improving management strategies, have been unavailable in China until now. We conducted a hospital-based, cross-sectional study of the hospital charts of CC patients younger than 18 years old from January 2005 to December 2010 at Zhongshan Ophthalmic Center (ZOC) in Guangzhou, China. Residence, gender, age at surgery, hospitalization time, and the presence of other ocular abnormalities were extracted and statistically analyzed in different subgroups. The search identified 1314 patients diagnosed with CC from a total of 136154 hospitalizations, which accounted for 2.39% of all the cataract in-patients and 1.06% of the total in-patients over the six-year study period. Of the identified CC patients, 9.2% had ≥ 2 hospitalizations due to the necessity of additional surgeries, with a total ratio of boys to girls of 1.75 ∶ 1. Based on a subgroup analysis according to age, patients 2-6 years old constituted the highest proportion (29.22%) of all hospitalized CC patients, and those 13-18 years old constituted the lowest proportion (13.47%) of the total number. The average age at surgery was 27.62 ± 23.36 months, but CC patients ≤ 6 years old (especially ≤ 6 months old) became increasingly prevalent throughout the 6-year study period. A total of 276 cases (20.93%) of CC were associated with one or more other ocular abnormalities, the highest incidence rates were observed for exotropia (6.24%), nystagmus (6.16%), and refractive error (3.65%). In conclusion, CC patients accounted for 2.39% of all cataract in-patients in a review of 6 years of hospitalization charts from ZOC. The age at the time of surgery decreased over the 6-year study period, which probably reflects the continuing improvement of public awareness of children's eye care in China.