Because the measurement of the retinal nerve fiber layer thickness is very sensitive to the position of measurement, it may be incorrect in patients with the tilted disc. In the present study, the corrected RNFL thickness by the optic nerve head configuration using the Cirrus HD OCT will be evaluated. If the corrected RNFL thickness is more sensitive to detect the localized RNFL defect, the present software should be upgrade to reflect the optic nerve head configuration.

Finding the localized retinal nerve fiber layer (RNFL) defect and measuring the RNFL thickness are two main issues for early glaucoma detection. A recently developed imaging device, the Cirrus HD OCT, offers more detailed informations about retina architecture including optic nerve head. To calculate the RNFL thickness, the software of the Cirrus HD OCT supposes an ideal optic nerve head. However, in the cases with not ideal optic disc configuration, the measurement of the RNFL thickness is not correct. Because the measurement of the RNFL thickness is extremely sensitive to the position of measurement, patients with the tilted disc are in danger of misdiagnosis. In the present study, we want to correct the RNFL thickness measurement according to the optic nerve head configuration using the Cirrus HD OCT. If the corrected RNFL thickness is more sensitive to detect the localized RNFL defect, the present software should be upgrade to reflect the optic nerve head configuration.

Inclusion Criteria:

• normal controls or glaucoma patients
• signal intensity of the OCT image > 8
• cooperative subjects

Exclusion Criteria:

• spherical equivalent refractive errors > +4 diopters or < -4 diopters
• significant media opacity
• previous intraocular surgery

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