Comparison of OCT and HRT findings among normal, normal tension glaucoma, and high tension glaucoma

To evaluate the relationship between optic disc and retinal nerve fiber layer (RNFL) measurements obtained with the optical coherence tomography (OCT) and the Heidelberg retina topography (HRT) in normal, normal tension glaucoma (NTG), and high tension glaucoma (HTG).

Normal, NTG and HTG subjects who met inclusion and exclusion criteria were evaluated retrospectively. One hundred seventy eyes of 170 patients (30 normal, 40 NTG, and 100 HTG) were enrolled. Complete ophthalmologic examination, HRT, OCT, and automated perimetry were evaluated.

Disc area, cup area and cup/disc area ratio measured with HRT were significantly different between NTG and HTG (all p < 0.05). Mean RNFL thickness measured by OCT with ascanning diameter of 3.4 mm was larger in NTG than HTG (84.97+/-24.20 micrometer vs. 73.53+/-27.17 micrometer, p = 0.037). Four quadrant RNFL thickness measurements were not significantly different between NTG and HTG (all p > 0.05). Mean deviation and corrected pattern standard deviation measured by automated perimetry was significantly correlated with mean and inferior RNFL thickness in both NTG and HTG (Pearson's r, p < 0.05). Mean RNFL thickness/disc area ratio was significantly larger in HTG than NTG (35.21+/-18.92 vs. 31.30+/-10.91, p = 0.004).

These findings suggest that optic disc and RNFL damage pattern in NTG may be different from those of HTG.