[Analysis of topograph and relevant factors of optic nerve head in normal subjects]

To study the optic nerve head (ONH) parameters and topograph features of normal subjects, and analyze the effect of gender, laterality, age and disc size on the topograph of ONH.

Heidelberg Retina Tomograph (HRT) was used to obtain the optic nerve head parameters and topograph images in 216 eyes of 116 normal volunteers. The impact of gender, laterality, age and disc size on the topograph was analyzed. The optic disc was divided into three groups by their size, small (less than 1.5 mm2), middle and large disc (equal or larger than 2.5 mm2), to evaluate the differences of parameters.

The parameters of ONH in normal eyes were as following: disc area (DA) (2.208 +/- 0.411) mm, cup area (CA) (0.466 +/- 0.355) mm2, cup/disk area ratio (C/DAR) (0.217 +/- 0.137), rim area (RA) (1.563 +/- 0.339) mm2, height variation contour (HVC) (0.404 +/- 0.096) mm, cup volume (CV) 0.127 mm3, rim volume (RV) (0.446 +/- 0.173) mm3, mean cup depth (MCD) (0.196 +/- 0.096) mm, maximum cup depth (MxCD) (0.559 +/- 0.228) mm, cup shape measure (CSM) (-0.213 +/- 0.076), mean retinal nerve fiber layer thickness (mRNFLT) (0.272 +/- 0.076) mm, and retinal nerve fiber layer cross section area (RNFLA) (1.364 +/- 0.375) mm2. There were significant differences between right and left eyes in C/DAR, RA and RV, but no difference between different genders in all parameters. A negative correlation was found between mRNFLT, RNFLA and age. There were significant differences in most parameters among three groups with different disc size, such as CA, C/DAR, CV, RA and CSM, but not in mRNFLT, RNFLA and RV.

Significant variations were found in parameters of ONH in normal subjects. Some parameters of ONH were affected by age and optic disc size. There were differences in some parameters between right and left eyes, but not between different genders. There were differences of parameters between different quadrants of ONH.