Keith Ong

Purpose
To report the histopathological features of a postoperative anterior capsular specimen from a 29-year-old man with atopic dermatitis and bilateral anterior subcapsular cataract (ASC).

Methods
The ASC tissue was obtained as an anterior capsulorhexis flap during routine cataract surgery. The anterior capsule with adherent lens epithelial cells (LECs) were fixed immediately in formalin and prepared as a wholemount. Phase-contrast microscopy was used to examine morphological features while detailed cellular characteristics were analysed by means of immunofluorescent staining for alpha-smooth muscle actin (_-SMA) and Hoechst 33342.

Results
The wholemount consisted of a well-demarcated central white plaque surrounded by transparent capsule, corroborating the slit-lamp biomicroscopic appearance. Ultrastructural evaluation of the plaque revealed a fibrous and amorphous mass of extracellular matrix (ECM) and the presence of irregularly arranged bundled strands suggestive of collagen fibrils. An evenly distributed monolayer of cuboidal LECs was evident directly adjacent to the plaque. Hoechst immunofluorescence of these LECs showed uniform round nuclei that differed significantly from the nuclei at the plaque which were more elongated and irregular, suggestive of myofibroblastic cells. Furthermore, these cell nuclei at the plaque were unevenly distributed with areas of multilayering. Elongated cells at the plaque were positive for _-SMA staining validating the presence of myofibroblastic cells.

Conclusions
The presence of _-SMA positive elongated cells at the plaque suggests that the cuboidal LECs may have transdifferentiated into spindle-shaped myofibroblastic cells that produce and deposit aberrant ECM. This transdifferentiation process, more commonly known as epithelial-mesenchymal transition, contributes to the development of human ASC.