A Study of the Human Anterior Lens Capsule (ALC) by Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM)

Abstract

Abstract: : Purpose:To study the structure and surface morphology of human ALC using atomic force microscopy (AFM) and the conventional scanning electron microscopy (SEM). Methods: ALCs (n=25) removed from senile cataract patients during the phaco–surgery were fixed in 10% formaline for more than 24 hrs. After being washed six times, five minutes each with distilled water, they were flat mounted onto the metal stubs with double adhesive tape. For SEM an electrical inductive tape was used. The specimens were examined directly under AFM or after vacuum coating with plated gold for SEM. Results: Under the SEM, the anterior surface of the ALC (the capsule side) was rather smooth. There was no obvious structure complexity except some folding. In contrast, the posterior surface of the ALC (the epithelium side) was seen to be rough. The lens epithelial cell bodies were clearly seen. Under high magnification, some blunt, bumpy ends of the lens fibers were seen. Cross–sectional view of the ALC revealed it to be homogenous and structureless. In most areas the matrix was even. Using the AFM, both the smoothness of the anterior surface, and the roughness of the posterior surface of the ALC were confirmed. Furthermore, lens fibers and its microfibrils on the posterior surface of the ALC that were undetectable under the SEM were clearly seen using the AFM. Conclusions: AFM is a powerful tool to study the surface structure and morphology of ocular tissues such as ALC. It is of higher resolving power than conventional SEM. The two techniques can be combined for exploration of the alteration of the ALC in various types of cataracts.

Keywords: microscopy: confocal/tunneling • microscopy: electron microscopy • imaging/image analysis: non-clinical