Electron microscopical study of the Fleisher ring

Area of Science:

• Ophthalmology
• Electron Microscopy
• Corneal Diseases

Background:

• The Fleischer ring is a characteristic sign observed in keratoconus, an ectatic corneal disorder.
• The precise composition and origin of the Fleischer ring have been areas of ongoing research.
• Understanding the ultrastructural basis of the Fleischer ring may provide insights into keratoconus pathology.

Purpose of the Study:

• To investigate the ultrastructural characteristics of the Fleischer ring in keratoconus using transmission electron microscopy.
• To identify the location and nature of ferritin particle accumulations within the cornea.
• To compare findings in keratoconus with normal human corneal and conjunctival tissues.

Main Methods:

• Transmission electron microscopy (TEM) was employed to examine four corneal buttons from patients with keratoconus.
• Normal human corneas and conjunctivas were also analyzed using TEM for comparative purposes.
• Detailed ultrastructural analysis focused on identifying and localizing ferritin particles.

Main Results:

• Accumulations of ferritin particles were identified in widened intercellular spaces and cytoplasmic vacuoles of the corneal epithelium in keratoconus.
• These ferritin deposits were predominantly found in the basal epithelial layers, with some observed in wing cell layers.
• Ferritin particles were also noted scattered over the corneal epithelium, in basal conjunctival cells, and within macrophages in the conjunctival stroma, but not in corneal stroma or endothelium.

Conclusions:

• The Fleischer ring in keratoconus is characterized by the deposition of ferritin particles within the corneal epithelium.
• The presence of ferritin in various corneal and conjunctival cell types suggests a complex deposition process.
• Further research is warranted to elucidate the exact origin and pathogenic role of these ferritin deposits in keratoconus.