Optical Coherence Tomography (OCT) and Ultrasonic Biomicroscopy in corneal diseases

Abstract

Abstract Purpose: To present the utility of ultrasound biomicroscopy (UBM) and anterior segment optical coherence tomography Visante (AS‐OCT) in the imaging of the human cornea. Methods: UBM and OCT analysis of healthy and pathological corneas are investigated, with the aim to define morphological/morphometric patterns of clinical relevance. Results: Cross sectional scans provided by UBM and Visante OCT enable morphological investigations of the cornea, ocular surface, and anterior chamber. Particularly AS‐OCT allows morphometric and quantitative analysis of the entire cornea, without invasiveness, together with corneal pachymetric maps. The anatomical relationships between the cornea and the adjacent anterior segment structures can be evaluated also in cases of loss of corneal transparency. Quantitative parameters can be obtained in cases of progressive corneal thinning, in degenerative and ulcerative diseases, descemetoceles, corneal oedema, and in the evaluation of post‐surgical corneal anatomy, such as lamellar interfaces, keratoplasties, ocular surface reconstruction, and amniotic membrane transplantation. Dynamic evaluations, over time, clearly allows clinicians to objectively assess variations of the corneal parameters (i.e. overall and sublayer thicknesses, lesion size, wound healing of stromal and transplanted tissues). Conclusions: UBM and AS‐OCT are complementary analysis to biomicroscopy, and furnish morphometric and objective parameters also when the cornea is opaque. Being non‐contact, and providing a higher resolution, AS‐OCT should be preferred in the investigation of acutely diseased or surgically treated corneas. Cross sectional morphology, tissue reflectivity assessment and precise measurements are the main advantages over traditional slit‐lamp examination.