The effects of vıtal dyes on mechanıcal propertıes of the human anterıor lens capsule

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

OBJECTIVE

This systematic review was undertaken to answer the research question: "In children with primary cataracts, what are the outcomes (posterior continuous curvilinear capsulorhexis + posterior chamber intraocular lens implantation) of surgery when performed with and without trypan blue staining of the posterior lens capsule?"

METHODS

An electronic search in six biomedical databases was conducted to identify randomised controlled trials that compared trypan blue with no stain during surgery in children 0 -16 years with primary cataracts. Titles and abstracts of studies published between 1946 and 2021 in English language were screened. Data extraction, risk of bias assessment and synthesis of findings were done by two independent reviewers, while conflicts were discussed and resolved with a third.

RESULTS

115 of 153 articles were screened after de-duplication. Of these, 113 were excluded while two randomised controlled trials involving 56 eyes of 42 partcipants were included in the review. The risk of bias was similar across all domains in both. Staining of the capsule led to complete posterior capsulorhexis and optimal placement of the implant in >90% of study eyes, while the control arms had 65% - 80% for both outcomes.

CONCLUSION

Use of trypan blue in paediatric cataract surgery probably leads to better outcomes, but more well-conducted randomised controlled trials on this important topic are needed.

Pathological Changes of the Anterior Lens Capsule

The anterior lens capsule (ALC), as the thickest basement membrane in the body, is an acellular, soft, smooth, transparent membrane secreted by lens epithelial cells. The ALC has its unique biomechanical properties to serve as a barrier and separate the lens from infectious viruses and bacteria together with the posterior capsule and pericapsular membrane. However, the biomechanical and ultrastructural properties of the ALC can be changed under certain conditions. Here, we provide a brief review of the pathological changes of the ALC in several eye disorders, including cataract, aniridia, climatic droplet keratopathy, exfoliation syndrome, true exfoliation syndrome, Alport syndrome, and silicone oil tamponade.

Mechanical properties of anterior lens capsule assessed with AFM and nanoindenter in relation to human aging, pseudoexfoliation syndrome, and trypan blue staining

The purpose of this study is the mechanical characterization of the mid-to- old-age human anterior lens capsules (ALCs) obtained by capsulorhexis using Atomic Force Microscopy (AFM) and a nanoindenter at different spatial scales. The dependencies on the human age, presence or absence of pseudoexfoliation syndrome (PEX), and application of trypan blue staining during the surgery were analyzed. The measurements on both the anterior (AS) and epithelial (ES) sides of the ALC were conducted and the effect of cells present on the epithelial side was carefully accounted for. The ES of the ALC had a homogenous distribution of the Young's modulus over the surface as shown by the macroscale mapping with the nanoindenter and local AFM indentations, while the AS was more heterogeneous. Age-related changes were assessed in groups ranging from the mid-age (from 48 years) to old-age (up to 93 years). We found that the ES was always stiffer than the AS, and this difference decreased with age due to a gradual decrease in the Young's modulus of the ES and an increase in the modulus of the AS. No significant changes were found in the mechanical properties of ALCs of PEX patients versus the PEX-free group, as well as in the properties of the ALC with and without trypan blue staining.

Research Progress of Drug Prophylaxis for Lens Capsule Opacification after Cataract Surgery

Phacoemulsification combined with intraocular lens (IOL) implantation is the international standard operation procedure for cataract and has been generalized worldwide. However, lens capsule opacification, one of the common complications after cataract surgery, impacts the recovery of patients' visual function to a large extent. Lens capsule opacification has two types, anterior capsule opacification (ACO) and posterior capsule opacification (PCO), according to the location. There is not an accepted approach to treat ACO. Nd : YAG laser capsulotomy, the common treatment of PCO, can effectively improve the vision, but may cause a series of complications and is inappropriate for children who are too young to cooperate with this treatment. It is generally known that the responses of lens epithelial cells (LECs) after cataract surgery, including cell proliferation, migration, and epithelial-mesenchymal transition (EMT), play a key role in the pathogenesis of lens capsule opacification. Scholars found that substantial drugs can reduce the occurrence of lens capsule opacification by inhibiting, clearing, or killing LECs, and made great efforts as well as innovations on the exploration of drug species or modes of administration. This article is a systematic interpretation and elaboration about how to prevent lens capsule opacification after cataract surgery via different drugs.