Clinical microscopy of the cornea utilizing optical sectioning and a high-numerical-aperture objective.

A doublet contact element was added to a long-working-distance objective to increase the numerical aperture to 0.75 and to maintain the focus during in vivo examination of the eye. Optical sectioning by use of confocal slits permits visualization of weakly scattering structures within the cornea. With photographic film and a 1/60-s exposure time to limit the effect of eye movement, an effective optical section half-thickness of approximately 20 microns was realized. Structures observed in the cornea include epithelial cells (surface, wing, and basal cells), nerve-fiber bundles in the subepithelial region, keratocytes and inflammatory cells in the stroma, and endothelial cells.