Elastic microfibril distribution in the cornea: Differences between normal and keratoconic stroma.

Area of Science:

• Ocular Biomechanics
• Corneal Histology
• Connective Tissue Biology

Background:

• The corneal stroma's collagenous structure dictates optical and biomechanical properties.
• Keratoconus involves stromal disorganization, leading to ectasia and vision loss.
• Elastic fiber networks (microfibril bundles, MBs) are present in the normal cornea.

Purpose of the Study:

• To compare elastic fiber distribution in normal versus keratoconic corneas.
• To investigate the role of microfibril bundles (MBs) in keratoconus pathogenesis.

Main Methods:

• Serial block face scanning electron microscopy.
• Transmission electron microscopy.
• Analysis of post-surgical keratoconic corneal buttons.

Main Results:

• Microfibril bundle (MB) distribution differs significantly in keratoconus.
• MBs are absent anterior to Descemet's membrane in keratoconic corneas.
• MBs are concentrated below the epithelium in keratoconic corneas, unlike normal corneas.

Conclusions:

• Altered MB distribution in keratoconus may represent a biomechanical response to anterior stromal weakening.
• The absence of MBs anterior to Descemet's membrane could contribute to keratoconus progression.
• Understanding MB changes offers insights into keratoconus pathogenesis and potential therapeutic targets.