An ophthalmologic appliance being an ultrasound probe positioning immersion shell for use in ultrasonic measurement of axial length of the eye ophthalmology and other procedures. Support members in an upper chamber and a lower chamber each provides accommodating support along and about a central axis of the ultrasound probe positioning immersion shell and about vertically spaced regions of ultrasound probes to provide for perpendicular alignment of ultrasound probes to the corneal plane. Vents in the chamber structure allow for introduction of fluid medium and for the expelling of air from the chambers to inhibit bubble formation.