Heidelberg Retina Tomography
Quick scan produces a 3-dimensional image of the optic nerve head
Early detection of glaucomatous change
The Heidelberg Retina Tomograph allows us to examine the head of the optic nerve at the back of the eye. The machine takes a series of images which scan into the end of the nerve at different depths using a technique called 'confocal microscopy.' Once the scan is complete, the computer assembles the images into a 3-dimensional image. Using other information about the eye, we can take measurements within the nerve head which can then be compared with a database on the machine. Images are stored in order that comparisons can be made at a later date, if neccessary.
Research projects, such as the OHTS Ocular Hypertension Treatment Study, have shown that the Heidelberg Retina Tomograph can detect early changes to the optic nerve before changes to the vision can be detected making this a good early-warning device.
The patient places their chin on a chin-rest and looks into the lens of the machine at a target. We may take several scans depending on what information is required. The HRT analyses the data in a number of different ways looking at the inside of the nerve head as well as the surrounding nerve fibre layer. The machine makes use of the Moorfields' Regression Analysis, a simple but powerful way of detecting abnormalities.
How Long Does This Take?
A typical set of scans may take about 5-10 minutes. This may take longer if there is a poor view of the back of the eye.