Purpose:
To evaluate the effect of myopia on the parapapillary retinal nerve fiber layer (RNFL) thickness measured by spectral-domain optical coherence tomography (SD-OCT) and scanning laser polarimetry (SLP).
Methods:
Myopic patients were invited to participate in this study. Through clinical examination, comprising visual acuity, slit lamp examination, indirect ophthalmoscopy, refraction, biometry (IOL Master, Carl Zeiss Meditec Inc., Dublin, CA). RNFL was evaluated, with SD-OCT, using Cirrus HD-OCT (software version 4.0, Carl Zeiss Meditec Inc., Dublin, CA) and Spectralis (software version 4.0, Heidelberg Engineering, Dossenheim, Germany), and with SLP, using the GDx VCC (software version 5.3.3, Carl Zeiss Meditec Inc., Dublin, CA). Parapapillary RNFL thicknesses were correlated with refraction and biometry. The correlations between these values and the axial length and spherical equivalent (SE) of refractive errors were analyzed, using the Spearman’s rank correlation coefficient. P < 0.05 was considered statistically significant.
Results:
Twenty-four eyes of twelve subjects were included. The mean spherical equivalent was -2.521 diopters (standard deviation [SD]: 1.966; range: -0.50 to -6.00). The mean axial length was 24.29 mm (SD: 1.29; range: 21.43 to 26.38). The mean (SD) RNFL measurements of the Cirrus, Spectralis, and GDx can be found in the table. The correlations between RNFL measurements and spherical equivalent as well as axial length ranged from weak to moderate (Table).
Conclusions:
The correlations between axial length and parapapillary RNFL thickness measured by Cirrus HD OCT were moderate and statistically significant for the Inferior Average and Average Thickness parameters. The other correlations analyzed were weak and had no statistical significance.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • myopia • nerve fiber layer