Outcomes of paediatric cataract surgery with and without the use of trypan blue

Author: AbdulRahman A, Bascaran C, Buchan J.

Geographical coverage: Not reported

Sector: Cataracts

Sub-sector: Treatment

Equity focus: Not reported

Study population: Children 0–16 years with congenital or developmental cataracts

Review type: Effectiveness review

Quantitative synthesis method: Narrative synthesis

Qualitative synthesis method: Not applicable

Background:
Cataract remains the leading cause of avoidable blindness in children globally. In paediatric cataract surgery, techniques often require preservation of the anterior and posterior lens capsules to support intraocular lens (IOL) implantation. However, leaving the posterior capsule intact can lead to posterior capsule opacification (PCO), a common complication that affects vision. To prevent this, a posterior capsulorhexis combined with anterior vitrectomy is typically performed, which is a technically challenging step requiring clear visualisation of the capsule. Trypan blue, a dye used to stain the transparent and elastic lens capsule, enhances visualisation, reduces elasticity, and increases stiffness, aiding in successful capsulorhexis creation. Despite being well-described in the surgical literature, the use of trypan blue in paediatric cataract surgery had not been systematically reviewed.

Objective:
To evaluate the evidence base regarding the effects of trypan blue as an intervention to aid posterior capsulorhexis and posterior chamber IOL (PCIOL) implantation during paediatric cataract surgery.

Main findings:
Two randomised controlled trials (RCTs) were included in the review, involving a total of 42 participants and 56 eyes. Both studies used parallel group designs and were conducted in different geographical settings, although the exact countries were not specified in the review. One study had a 3-month follow-up and included children aged 5–12 years, while the other had a 12-month follow-up and included children aged 0.5–4 years. The risk of bias was similar across both studies.

For the primary outcomes, trypan blue staining resulted in >90% success rates for completeness of posterior capsulorhexis and optimal PCIOL positioning in both studies. In contrast, the control groups (no staining) achieved 65%–70% for PICOL placement and 65%-80% for the completion of posterior capsulorhexis.

Methodology:

The search was conducted in Embase, Medline, Cochrane Library, ClinicalTrials.gov, International Clinical Trials Registry Platform, and International Standard Randomised Controlled Trial Number Registry to identify prospective RCTs conducted on children aged 0-16 years with congenital or developmental cataracts and comparing trypan blue versus no stain. The studies were included if they were peer-reviewed and published in English between 1st January 1946 and 23rd March 2021. Reference lists of the relevant articles were screened to identify additional relevant publications.

Two reviewers independently screened the potentially relevant articles against the eligibility criteria. Disagreements between the reviewers were resolved by contacting a third reviewer. The data was extracted by one reviewer and checked by a second reviewer. Any errors or differences were discussed to arrive at a consensus. Two reviewers independently assessed the methodological quality of the included studies using The Critical Appraisal Skills Program for Randomised Controlled Trials checklist and resolved disagreements through discussions. The findings were synthesised narratively.
Only one study reported the size of the posterior capsulorhexis, and differences in PCIOL positioning techniques limited direct comparison between studies, thus preventing meta-analysis.
Applicability/external validity:
The authors acknowledged that the review included only two studies involving children from different age groups (0–4 and 5–12 years) and that differences in surgical outcomes could be due to age-related anatomical variations. They also identified key methodological limitations, including unclear randomisation procedures and lack of masking, which could introduce bias. Consequently, the review highlighted the need for well-designed, large-scale randomised controlled trials to enhance the reliability and generalisability of its findings.
Geographic focus: The authors did not apply any geographical limits. However, they did not report the geographical location of the two included studies.
Summary of quality assessment: Overall, there is medium confidence in the review’s conclusions. The review was methodologically robust, with clearly defined inclusion and exclusion criteria. Searches were comprehensive, and two reviewers independently screened studies, extracted the data and assessed the risk of bias using established tools. Findings were synthesised narratively, and heterogeneity among included studies was thoughtfully addressed. However, the review was limited to peer-reviewed articles published in English, and a list of excluded studies was not provided.