Variations in optic nerve head morphology by intraocular pressure in open-angle glaucoma.

PURPOSE

To compare optic disc topography in eyes in three intraocular pressure (IOP) groups of <15 mmHg, 15-20 mmHg, and ≥21 mmHg using spectral domain optical coherence tomography (SD-OCT) and confocal scanning laser ophthalmoscopy, adjusting for the degree of damage, as measured by retinal nerve fiber layer (RNFL) thickness and average visual field loss.

METHODS

A total of 184 eyes of 112 patients with primary open-angle glaucoma were recruited into groups based on baseline untreated intraocular pressure (IOP) of <15 mmHg (normal-tension glaucoma [NTG], very low), 15-20 mmHg (NTG, medium), or ≥21 mmHg (high-tension glaucoma [HTG]). Patients underwent scanning laser ophthalmoscopy, SD-OCT, and Humphrey visual field testing. Univariate and multivariate models were created, accounting for degree of retinal ganglion cell (RGC) loss by either OCT RNFL thickness or visual field mean deviation (MD).

RESULTS

Univariate and multivariate analyses demonstrated no morphological differences in HRT or OCT parameters among IOP groups that met Bonferroni-corrected statistical significance when using either MD or OCT RNFL as the damage criterion (p < 0.0063). The mean cup depth was shallower for the IOP <15 mmHg group than the IOP ≥21 mmHg group (p < 0.05) for both MD (p < 0.011) and OCT RNFL (p < 0.014).

CONCLUSION

Normal-tension and high-tension glaucoma are not distinguishable by optic nerve head topography with HRT and OCT when the degree of damage by Humphrey visual field testing is taken into account.