Visual Vertical
Accurate bedside measurement of subjective visual vertical — a sensitive, otolith-specific test of vestibular and brainstem function, on the iPhone and iPad already in your pocket.
An otolith-specific window your other bedside tests don't give you
When you ask a patient to set a line to vertical without visual cues, you're probing the balance of graviceptive tone between the left and right vestibular systems — driven chiefly by the utricle. A reproducible tilt suggests an asymmetry that points toward peripheral vestibular loss, or, via the ocular tilt reaction, central and brainstem pathology. Most healthy individuals sit within about ±2° of true vertical.
How it works
No costly hardware. Just your device, a bucket and a bit of Blu Tack — set up in under a minute.
Mount your iPhone in the base of a bucket so the patient sees only the screen — removing every external reference to vertical.
The patient rotates the on-screen line to their perceived vertical. Repeat across a few trials for a reliable result.
The app captures each reading in degrees, so you can note deviation and direction and compare on review.
Examined in peer-reviewed research
The app has been directly validated against traditional equipment in a published study, applied in clinical research across patient populations, and referenced in the field's leading clinical text on vestibular rehabilitation.
"A simple, quick, and useful method for detecting peripheral vestibular loss in paediatric patients in the clinic setting."
"Mobile phone app vs bucket test as a subjective visual vertical test: a validation study" — directly comparing the app against the traditional bucket method.
Vestibular Rehabilitation, 4th edition — the definitive clinical text in the field, edited by Susan Herdman.
"An invaluable 'bedside' evaluation tool — previously such an assessment was only available through costly, inaccessible diagnostic laboratories."
"Quick n easy, brilliant."
"Simple to use and easy to track."
Who it's for
Objective tracking of otolith function across a course of care.
A bedside sign in the work-up of brainstem and central lesions.
A fast, otolith-specific complement to canal-based testing.
Common questions
An iPhone or iPad, an ordinary bucket, and a small piece of Blu Tack to mount the device. That's the whole kit.
It uses the device's calibrated sensors to read the line angle in degrees, and the method has been examined in peer-reviewed clinical research as a reliable bedside test.
Visual Vertical is a one-time purchase on the App Store — a fraction of the cost of dedicated laboratory equipment. See the App Store for current pricing.
Yes — registered users receive our guide to interpreting subjective visual vertical and the ocular tilt reaction. Get in touch if you'd like a hand getting started.
Add SVV to your exam today
Download Visual Vertical and start taking accurate, trackable readings in minutes.