Pediatric cataract and posterior capsular opacification: Can trypan blue be the solution?

We read with great interest this article reporting the histopathological images showing the effects of trypan blue on lens epithelial cells (LECs), which can potentially lead to a fall in the incidence of posterior capsular opacification (PCO). The approach to prevent PCO is dual-faceted. The first aspect involves inhibiting the growth of LECs, while the second focuses on stopping any proliferated LECs in the capsular fornix from migrating to the visual axis. The latter can be accomplished by ensuring an adequately sized capsulorhexis covering the intraocular lens (IOL) optic all around, selecting the right IOL material, and having a 360° square edge that confines the LECs to the capsular periphery, thereby preserving the optical clarity of the visual axis.[1-3] The removal of a maximum number of LECs with a good cortical cleanup and capsular polish can be supplemented with the use of specific agents (antimitotic agents; e.g. mitomycin C, lidocaine, and trypan blue) that are toxic to LECs. A sealed irrigation bag system has also been introduced to wash the capsular fornices with various antimitotic agents to limit the antimitotic activity in the capsular bag and prevent endothelial damage. However, these devices did not gain popularity due to limited applicability and the short-lasting effect of chemical agents in preventing the occurrence of PCO.[4,5] There are reports of staining of IOL material with vital dyes, especially for expandable hydrophilic IOLs.[6] The cases are rare these days; however, a surgeon using trypan blue to wash the capsular bag needs to be careful about the same. The hydrophilic IOLs tend to absorb the fluid in the vicinity, and minor traces of trypan blue in the anterior chamber can lead to permanent staining of these IOLs with the dye. Joshi et al.[5] reported no advantage of trypan blue in PCO prevention at the end of 3 months post cataract surgery. In addition, there are concerns over endothelial and retinal pigment epithelial toxicity of trypan blue, thus mandating the need for an air cushion while staining the anterior capsule or capsular bag and the need to avoid its use in patients with compromised zonules. With most of the modern IOLs with hydrophobic material and square edge profile, the incidence of VAO in adults can be markedly mitigated by ensuring adequate cortical cleanup and appropriate positioning of the IOL in the bag with capsulorhexis margins covering the optic all around well. Even if VAO occurs, it can be managed well with Neodymium-doped Yttrium Aluminum Garnet (Nd YAG) capsulotomy, which has good outcomes. However, the development of VAO in children is not that easy to treat, and if left untreated, it can have grave visual outcomes.[7] We conducted a study to identify risk factors associated with the development of VAO in the pediatric age group. The important factors that appeared in our study were lower age and poor socioeconomic status. Cataracts with anterior and posterior capsular plaques and the presence of posterior synechiae and pupillary membranes are associated with a higher prevalence of development of VAO. Small posterior capsulorhexis, inadequate anterior vitrectomy and malposition of IOL (single piece in sulcus or decentered IOL with capsulorhexis not covering the IOL all around) have been associated with VAO [Fig. 1]. We also studied the histopathological and electron microscopic images of patients with pediatric cataracts and anterior capsular plaques. The plaques showed signs of epithelial-mesenchymal transition. Histopathology of anterior capsules with plaque showed fibrosis and calcification [Fig. 2]. The LECs were found to be dilated, with an increased number of organelles, intermediate and tonofilaments, and fragmented phagosomes [Fig. 3].[8] In conclusion, the histopathological evidence of the epitheliotoxic effect of trypan blue on LECs in terms of degeneration and detachment of LECs from the basement membrane as found by the authors of this study presents a convincing rationale for further exploration of the effectiveness of trypan blue in preventing VAO in pediatric cataract cases. This could lead to a new addition to the current armamentarium for preventing VAO, thereby improving visual outcomes in the pediatric population. However, the potential risks and benefits must be carefully weighed, keeping in mind the unique challenges posed by pediatric cases. As we continue to refine our techniques and understanding, the goal remains clear – to preserve and enhance visual function in all patients.Figure 1: Various morphological features of fibrotic VAO. (a) Combined inflammatory with fibrotic VAO in a patient with decentered IOL with inferior pupillary capture; (b) Fibrotic VAO with posterior synechiae; (c) Dense fibrotic VAO with posterior synechiae in a pseudophakic eye; (d) Fibrotic VAO with posterior synechiae in an aphakic eyeFigure 2: Histopathological images of anterior capsules with plaque. (a) Anterior lens capsule showing calcification; (b) Anterior lens capsule showing calcification along with fibrosis; (c) Anterior lens capsule showing marked proliferation of lens epithelial cells; (d) Uniformly thickened anterior lens capsule, randomly scattered LECs with subepithelial fibrosisFigure 3: Electron microscopy images of anterior capsules with plaques. (a) Randomly arranged collagen fibers in the region of capsular plaque; (b) Increased number of organelles with swollen rough endoplasmic reticulum (black arrow), mitochondria (white arrow), and lysosome (red arrow); (c) Swollen lens epithelial cell with clumped up chromatin; (d) Metaplastic lens epithelial cells with clumped chromatin and fragmented nuclei