Purpose:
To evaluate the false-positive (FP) rate in retinal nerve fiber layer thickness using both RNFL and axonal-N site protocol color code results from spectral-domain optical coherence tomography (Spectralis SD-OCT) and to determine the factors that contribute to this FP rate.
Methods:
A prospective, cross-sectional study including 80 eyes from 40 healthy participants without previous ocular surgery or family history of glaucoma. Participants who were consecutively enrolled from October 2011 to December 2011, underwent Spectralis OCT and were tested by RNFL and N-site axonal protocol. Definition of normal eyes was based in global VF parameters. Recorded demographic and clinical factors included age, gender, eye side, intraocular pressure, central corneal thickness, spherical equivalent, axial length. Quadrant and clock-hour maps with ≥ 1 yellow or red sectors were considered abnormal. The influence of clinical and demographic factors on the incidence of false-positive RNFL or axonal-N site color codes was assessed using linear mixed model analysis.
Results:
The incidence of FP for the quadrant map was 15% and 18.75% for RNFL and N-site axonal protocol respectively. The supero-nasal quadrant map exhibited the highest incidence of FP witn both protocols. There were no significant correlation between FP rate and central cornea thickness, axial length or spherical equivalent.
Conclusions:
FP rate in RNFL or axonal acquisition protocols of Spectralis-OCT seems to be lower than previously reported by Kim et al with Cirrus- OCT (26%) and contrary to that report axial length and spherical equivalent did not affected that rate. Similar to Cirrus-OCT, the highest FP rate was found in the superior quadrant.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • ganglion cells • optic nerve