We used the Humphrey Ultrasound Biomicroscope (UBM System 840 by Zeiss-Humprey Instruments, San Leandro, Calif. USA) to study various corneal oedemas and leucomas. This UBM system, using a high-resolution probe of 50 Mhz, has an axial and lateral resolution of about 50 micrometer. We analysed 36 eyes divided into two groups, 27 (group A) affected by corneal oedema caused by traumatic-mechanic or phlogistic-toxic lesions, 9 (group B) affected by postsurgery oedema. Thanks to its high-resolution power, we could study their pathogenesis and their clinical evolution and so arrange a suitable therapy and perform an accurate follow-up of these pathologies.