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The Heidelberg retina tomograph in glaucoma
Author(s) -
Hosking S. I.
Publication year - 1996
Publication title -
ophthalmic and physiological optics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.147
H-Index - 66
eISSN - 1475-1313
pISSN - 0275-5408
DOI - 10.1046/j.1475-1313.1996.96849726.x
Subject(s) - optic nerve , glaucoma , fundus (uterus) , visual field , ophthalmology , optic disc , medicine , retina , nerve fiber layer , optics , optometry , physics
Purpose: To establish the ability of the Heidelberg retina tomograph (HRT) to detect morphological change of the optic nerve head in glaucomatous optic neuropathy and to evaluate glaucomatous nerve fibre layer defects. Introduction: The HRT is a confocal laser scanning microscope designed for three‐dimensional imaging and measurement of the in vivo fundus. The light source is a diode laser operating at a wavelength of 670 mm. Thirty‐two single, two‐dimensional sectional images are recorded within 0.032 s with a repetition rate of 20 Hz, digitised in a frame of 25 × 256 pixels. Sequential viewing of the plates permits three‐dimensional resolution of the image. Use of the HRT enables comparison of change in optic nerve head morphology with change in visual function. Methods: The sample consists of 30 early primary open angle glaucoma subjects showing repeatable glaucomatous field defects on Humphrey 30‐2 analysis and 65 glaucoma suspects with normal Humphrey 30‐2 fields but with multiple risk factors for the development of glaucoma. All subjects are evaluated using white‐on‐white and blue‐on‐yellow visual fields as well as HRT analysis of the optic nerve head and retina at three‐month intervals over a 15‐month period. Discussion: We have demonstrated the need for consistent image scaling in prospective follow‐up (Hosking et al. , 1995), a facility to be incorporated in the next software revision; the importance of selecting an optimum scan; and that the correction of astigmatism required for quality image acquisition results in image distortion. The application of nerve head analysis software to demonstrate localised wedge‐shaped nerve fibre bundle defects is illustrated and further modification of the software to demonstrate more subtle subclinical nerve fibre layer defects will be discussed.