The Quantitative Evaluation of Optic Ne rve Head of Normal Tension Glaucoma

ABSTRACT

It is known that optic disc morphology is different between high tension glaucoma[HTG]and normal tension glaucoma[NTG]. We quantitatively evaluated optic nerve head by confocal scanning laser ophthalmoscope [CSLO]to determine if substantial morphological differences between the HTG and the NTG could be identified. 21 patients[21 eyes]in the early NTG and 32 patients[32 eyes]in the early HTG were matched for visual field defect[MD>-10dB].The optic nerve head was evaluated by Heidelberg Retina Tomograph[HRT]and 12parameters provided by HRT were compared between NTG and HTG. The mean age of patients was 56.6 +/-13.6 years in NTG and 48.9 +/-14.7 years in HTG, respectively[p>0.05].Mean MD was -5.4 +/-1.9dB in the NTG, -5.0 +/-2.5dB in the HTG, respectively[p>0.05]. Disc area was slightly lager in the NTG than in the HTG, but the difference did not reach statistical significance[p>0.05].The neuroretinal rim area was significantly larger in the NTG than in the HTG[p<0.05], whereas the mean cup depth was significantly smaller in the NTG than in the HTG[p<0.05].Among the 12 parameters, cup area, rim area, cup volume, mean cup depth, and maximum cup depth in the NTG had significant correlations with CPSD in the visual field index.These findings further support the hypothesis that there may be different mechanisms in the glaucomatous optic nerve damage.