Heidelberg Retina Tomograph in Glaucoma

The Heidelberg Retina Tomograph (HRT) has been available in the clinical practice for over a decade. The device utilizes the principle of confocal scanning laser ophthalmoscopy to acquire three-dimensional topographical images of the optic nerve head. The basic principles of image acquisition are discussed, along with the use of the HRT in assisting clinicians to discriminate between normal and glaucomatous optic discs and to detect glaucomatous progression. The native software incorporates a number of easily interpreted classification algorithms such as the ‘Moorfields Regression Analysis’ and the ‘Glaucoma Probability Score’. When using the HRT to aid diagnosis, clinicians should use clinical information to judge the ‘pre-test probability’ that glaucoma is present together with the information supplied by the HRT to derive the ‘post-test probability’ of a patient having a diagnosis of glaucoma. Methods to improve the signal to noise ratio are central in improving the detection of progression using longitudinal HRT imaging.

Keywords: Glaucoma, optic disc, optic cup, cup-to-disc ratio, neuroretinal rim, retinal nerve fibre layer, glaucoma diagnosis, glaucoma progression, rim area, rim volume, cup volume, optic nerve head, glaucoma monitoring, imaging, laser.