Corneal microcysts are best visualized via biomicroscopy with which method of illumination?

Corneal microcysts are best visualized using retroillumination because this technique enhances the visibility of subtle corneal structures. Retroillumination involves shining light at an angle from behind the cornea, allowing any irregularities or features within the cornea, such as microcysts, to stand out more prominently against the illuminated background. This method highlights the differences in refractive indices and optical density within the corneal layers, making conditions like microcysts more easily identifiable.

By using retroillumination, clinicians can better discern these cysts due to the way the light interacts with the surface of the cornea and the cysts themselves, often resulting in a contrast that facilitates their detection. This is particularly important in diagnosing and managing corneal conditions, thus enhancing patient care.