The Heidelberg Retina Tomograph (HRT) is one of the most common laser scanning tomographs currently in use. It is also referred to as a laser scanning ophthalmoscope. The HRT is an ophthalmic procedure that allows three-dimensional topographic structural analysis of the optic disc (exit site of the optic nerve from the eyeball) and the surrounding retina.
Indications (areas of application)
The Heidelberg Retina Tomograph is of diagnostic importance primarily in the early detection of glaucoma. The following aspects of the examination should be emphasized:
- Measurement of the optic disc
- Detection of an excavation (hollowing) of the optic disc (an excavation of the optic disc is caused by increased intraocular pressure and is characteristic of glaucoma. However, this usually occurs long before visual field loss occurs, thus early diagnosis provides valuable time for treatment).
- Progress monitoring of optic disc findings (recording of individual changes in individual optic discs. Especially here, the clarity of the imaging of the HRT is very advantageous, as it simplifies the comparison).
- Derivation of visual field defects (detection of damage on the three-dimensional images leading to visual field defects (scotomas)).
The procedure Laser scanning tomography belongs to the group of imaging techniques. The optic disc area and the surrounding retina are scanned with a laser and imaged layer by layer at high magnification. This procedure is non-invasive, which means it is particularly gentle. The patient rests his or her head on a chin rest and fixes a predetermined point while the examining ophthalmologist applies the procedure. Pupil-dilating eye drops are usually not necessary. A computer calculates a spatial profile of the tissue from the intensity of the reflected light. The images produced are particularly characterized by a high depth of field and richness of contrast; in addition, media opacities (e.g., opacity of the vitreous body of the eye) have only minor effects on the quality. The data obtained can be compared with data sets of healthy patients or used to monitor the course of a progressive disease such as glaucoma.
Note: Drug-induced pupil dilation (mydriasis) is not required.
Possible complications
Because the HRT does not touch the eye and uses only low-level light that does not damage these cells, it is not expected to cause direct damage if used properly.
