Exophthalmometer
An exophthalmometer is an ophthalmological examination device with which the protrusion of the eyeballs ( protrusio bulbi, exophthalmus ) can be measured and quantified. This is a necessary diagnostic measure , especially in the clinical picture of endocrine orbitopathy .
The exophthalmometer, named after the German ophthalmologist Ernst Hertel , which works with a mirror system, has established itself as the most common method. During the investigation which is sagittal spacing of cornea ( cornea ) from the lateral edge of the bony orbit ( orbit measured). Values over 20 millimeters or a side difference of more than 2 millimeters are considered pathological.
Another device that is easy to use and provides easily reproducible values is the Luedde exophthalmometer . It is a transparent ruler that is calibrated on both sides and placed on the lateral edge of the orbit. The scales on both sides prevent an equatorial shift when reading and thus allow an accurate measurement.
The exophthalmometry using ultrasound according to Buschmann is combined with the measurement according to Hertel in order to determine the position of the globe in the orbit. Here, too, the lateral limitation of the eye sockets is used as a reference point. Since the axial length of the eye is also included in the ultrasound measurement, incorrectly interpretable measurements can be avoided with higher axial ametropia , as they occasionally occur with measurements exclusively with the Hertelian exophthalmometer.
Due to various factors such as the spread of the standard values, different measurement results from different examiners, asymmetries of the facial skull and so on, the absolute values must be evaluated with care. Rather, the clinical significance lies in the comparative measurements over time . In addition, you should only ever compare results that have been determined using identical methods.
literature
- Theodor Axenfeld (founder), Hans Pau (ed.): Textbook and atlas of ophthalmology. With the collaboration of Rudolf Sachsenweger and others 12th, completely revised edition. Gustav Fischer, Stuttgart et al. 1980, ISBN 3-437-00255-4 .
- Lothar Andreas Hotze, Petra-Maria Schumm-Draeger: Thyroid diseases. Diagnosis and therapy. 5th, enlarged and completely revised edition. BMV Berlin Medical Publishing House, Berlin 2003, ISBN 3-88040-002-4 .
- Dagmar Reiche (Red.): Roche Lexicon Medicine. 5th, revised and expanded edition. Elsevier, Urban & Fischer, Munich 2009, ISBN 978-3-437-15157-6 .
