Use of a confocal laser scanning ophthalmoscope to detect glaucomatous cupping of the optic disc.

PURPOSE

The aim of the present study was to test the hypothesis that the three-dimensional (3-D) topography of the optic disc contains sufficient information to diagnose glaucoma with a high degree of reliability.

METHODS

The Zeiss 'Confocal Laser Scanning Ophthalmoscope' (CLSO) was used to obtain digitized samples of 3-D images of optic nerve heads from the following three groups of patients: (i) 40 normals with normal optic discs, normal Humphrey 24-2 full threshold visual fields and an intraocular pressure (IOP) < or = 21 mmHg, (ii) 20 established glaucoma patients with cupping, glaucomatous field loss and an IOP > 21 mmHg; and (iii) 20 early glaucoma patients with early cupping, field loss with a mean defect less than -10 dB and IOP > 21 mmHg. The cupping in these patients was paramaterized by spherical harmonics and was classified by multivariate statistical analysis.

RESULTS

Of 40 glaucoma patients, 39 were correctly classified. Of 40 normal patients one was classified as glaucoma.

CONCLUSIONS

This study demonstrates that the CLSO, with the use of spherical harmonics, can differentiate glaucomatous from normal optic discs in this selected group of patients without the need for a skilled observer. This constitutes a promising technique to be tested on a large, unselected body of patients as a screening tool.