Similar to von Graefe's sign, it is observed in people with Graves-Basedow disease, a type of hyperthyroidism. In this disease, the immune system attacks the thyroid gland and the soft tissues surrounding the eyes. As a result, the eyes are often pushed forward in the eye sockets, a condition known as exophthalmos.
- Cline D; Hofstetter HW; Griffin JR. Dictionary of Visual Science. 4th ed. Butterworth-Heinemann, Boston 1997. ISBN 0-7506-9895-0