Cone of light

Not to be confused with the Light cone.

The Cone of light, or light reflex, is a visible phenomemon which occurs upon examination of the tympanic membrane with an otoscope.[1] Shining light on the tympanic membrane causes a cone-shaped reflection of light to appear in the anterior inferior quadrant. This corresponds to the 4 o'clock to 5 o'clock position in the right eardrum and the 7 o'clock to 8 o'clock position in the left eardrum.[2] The apex of the cone is at the most depressed part of the tympanic membrane, known as the umbo.[3]

Absence of a cone of light

The absence of a cone of light does not necessarily signify an ear disorder, as it could be due to the slope of the tympanic membrane or the shape of the ear canal.[4] However, distortions in the cone of light can also be a sign of increased inner ear pressure or otitis media.

References

  1. ↑ Stanley Gelfand (19 March 2009). Essentials of Audiology. Thieme. p. 40. ISBN 978-1-60406-155-0.
  2. ↑ Cone of Light Anatomy - http://www.webster.edu/~davittdc/ear/tympanic/tympanic.htm
  3. ↑ Advanced Therapy in Otitis Media. PMPH-USA. 2004. p. 56. ISBN 978-1-55009-201-1.
  4. ↑ Robert Thayer Sataloff; Joseph Sataloff (24 April 2006). Occupational Hearing Loss, Third Edition. CRC Press. p. 38. ISBN 978-1-4200-1547-8.
This article is issued from Wikipedia - version of the Saturday, January 25, 2014. The text is available under the Creative Commons Attribution/Share Alike but additional terms may apply for the media files.