Alteration in epithelium and stroma of Post-INTACS cornea: Ultrastructure and 3D transmission electron tomography

This study was conducted to investigate the ultrastructure of the epithelium and stroma of post-INTACS corneas. INTACS were surgically inserted into the corneas of three patients to remodel the keratoconus shape. INTACS were inserted with the IntraLase femtosecond laser. Patients 1, 2, and 3 returned to the clinic 8, 6, and 9 years, respectively, after surgery due to their deteriorating vision. The lamellae above the INTACS were removed surgically and processed for light and electron microscopy. 2D and 3D digital images of lamellae, collagen fibrils (CFs), and proteoglycans (PGs) were captured by a bottom-mounted camera and analysed using iTEM software. The epithelium and stromal lamellae had degenerated. A large number of aggregates of microfilaments were present in the Bowman's layer (BW) and throughout the stroma. In the stroma, just above the INTACS insertion, lamellae were completely disorganised and running randomly in the large electron-lucent spaces. The CF diameter was significantly smaller than in the normal cornea. 3D images showed microfibrils within the CF were less in the post-INTACS cornea than in the normal cornea. We believe that insertion of the INTACS disturbed the lamellar organisation and uniform distribution of CFs. This non-uniform CF distribution increased over time, resulting in vision impairment.