Polarimetric Interferometry: New Technique for Assessment of Corneal Stromal Lamellae Orientation
To analyze corneal stromal lamellae orientation in normal subjects and in patients with various corneal conditions using a novel polarimetric interferometry device (Lumaxis, Phronema srl)
Observational study. 32 patients (62 eyes) healthy control subjects and 16 patients (25 eyes) with corneal affections/post-keratoplasty were included in the study. All patients were imaged using the Lumaxis interferometer and slit lamp photography. Corneal haze was graded semi-quantitatively on a scale from 0 to 4. Keratometry, central corneal pachymetry and corneal densitometry were also obtained with Scheimpflug corneal tomography (Pentacam, Oculus).
The Lumaxis interferometer produces an orthogonal cross-like image of stromal lamellae by illuminating the cornea in phase-light polarization angle. The cross-like image was observed in all healthy control subjects and in 13/16 patients (22/25 eyes) with total corneal neovascularization/scarring, central leukoma and failed DALK, respectively. Identification of the cross-like image was influenced by corneal haze grade and densitometry (p<0.05), but not by pachymetry or keratometry (p>0.05). There was no correspondence between the orientation of the corneal meridians and the position of the two arms of the cross-like image.
Corneal stromal lamellae orientation can be efficiently assessed and displayed as a cross-like image by the Lumaxis interferometer. Observation of the orientation pattern is consistent with previous X-rays and second harmonic generations studies on corneal stromal fibers orientation. Stromal lamellae orientation imaging could have potential implications in corneal diagnostics and surgery.