Contact glass
As a contact lens special are ophthalmic examination instruments referred to, which have the shape of a funnel-shaped magnifying glass. Inside there can be one to four differently inclined mirrors on the edge. The contact lens is a technically high-quality solution for biomicroscopic fundoscopy for assessing the fundus , the middle sections of the eye and especially the outer periphery of the retina , as well as for inspecting the chamber angle ( gonioscopy ). It enables a binocular , stereoscopicViewing at a high magnification. It is used together with a slit lamp .
variants
- The Goldmann three-mirror contact lens has three mirrors: two mirrors for examining the retinal periphery and another for examining the chamber angle (inclination angle of 59 °). The examination is carried out on the slit lamp after surface anesthesia, whereby a viscous substance is required between the cornea and the contact glass. By rotating the three-mirror contact glass by 360 °, the chamber angle can be viewed in a circular manner.
- The Zeiss glass has 4 mirrors with an inclination angle of 64 °. It is therefore used exclusively to examine the chamber angle. It is not necessary to turn the glass during the examination. Due to the flatter radius of curvature, a viscous substance is not required. By applying pressure to the cornea, the Zeiss glass can be used to redistribute fluid in the anterior chamber so that the chamber angle is widened. As a result, an acute-angled, invisible chamber angle can be widened so far that goniosynechiae can be seen. This so-called single gonioscopy can be used to differentiate acute angle-closure glaucoma without goniosynechiae from chronic angle-closure glaucoma with goniosynechiae.
handling
Contact glasses are placed on the patient's cornea, which has previously been locally anesthetized , with the view through the slit lamp microscope. The investigation of the posterior pole is done through the central part of the funnel. The least inclined mirror allows a view of the area of the globe equator . The middle mirror enables the peripheral areas of the retina to be assessed in front of the equator. The most inclined mirror is responsible for assessing the chamber angle.
development
The three-mirror contact lens was developed by the Austrian-Swiss ophthalmologist and inventor Hans Goldmann .
swell
- Franz Grehn: Ophthalmology. Berlin: Springer Verlag, 30th edition, 2008, page 41 ff. ISBN 978-3-540-75264-6
- Th. Axenfeld (conception), H. Pau (ed.): Textbook and atlas of ophthalmology. With the collaboration of R. Sachsenweger et al., Stuttgart: Gustav Fischer Verlag, 1980, page 274. ISBN 3-437-00255-4
