Purposes: To evaluate the effects of axial length and age on the circumpapillary retinal nerve fiber layer (cpRNFL) and the inner macular parameters measured using 3 spectral-domain optical coherence tomography (OCT) instruments.
Methods: A total of 102 normal eyes (1 eye per subject) were imaged using Cirrus, RTVue, and 3D-OCT. The cpRNFL and the macular retinal nerve fiber layer (mRNFL), the ganglion cell layer+inner plexiform layer (GCLIPL), and the mRNFL+GCLIPL ganglion cell complex, GCC thicknesses were analyzed. The correlations between these values and the axial length or age were evaluated using a partial correlation analysis. These correlations were corrected using the axial length-related magnification effect.
Results: All but the nasal quadrant cpRNFL thicknesses and GCC thicknesses obtained using the 3 OCT instruments were significantly correlated with age. The average cpRNFL thickness and GCC thickness measured using the Cirrus and RTVue, but not by the 3D-OCT, had a negative correlation with the axial length. The temporal quadrant cpRNFL thickness measured using the 3 instruments was positively correlated with the axial length. The magnification correction made the most correlations positive.
Conclusions: The average cpRNFL and GCC thicknesses measured using these 3 instruments decreased with age. The axial length affected the cpRNFL and GCC thicknesses as measured using the Cirrus and RTVue; this effect likely depended on the fundus area of analyses.