Abstract
Purpose: :
Unlike the Stratus time-domain optical coherence tomography which allows only total macular thickness measurements, the RTVue (Optovue, Fremont, CA), a Fourier domain optical coherence tomography device (FD-OCT), can provide automatic measurements of inner retinal layer (IRL) thickness, which is the sum of nerve fiber, ganglion cell and innerplexiform layers. In order to evaluate usefulness of IRL thickness measurements, we analyzed difference in the IRL thickness in macular region between superior and inferior hemisphere and also analyzed correlation with visual filed defects in glaucomatous eyes with hemifield defects.
Methods: :
Twenty-three eyes of 18 glaucoma patients with visual field defects located dominantly in either superior or inferior hemifield were enrolled (superior hemifield defects: 16 eyes, inferior hemifield defects: 7 eyes). All subjects were scanned with the RTVue’s Macular Mapping 7mm (MM7) scan pattern to obtain an IRL thickness map centered on the fovea. The difference in IRL thickness measurements was compared between the hemisphere corresponding to the hemifield with visual field defects (worse hemisphere) and that corresponding to the hemifield without defects (better hemisphere). The correlation of the IRL thickness with the sum of total deviation (TD) or pattern deviation (PD) value in the Humphrey visual filed corresponding to each hemisphere was also evaluated.
Results: :
The IRL thickness in the worse hemisphere was significantly thinner (73.5 ± 9.6 µm) than that in the better hemisphere (83.5 ± 10.3 µm) (p=0.001). The IRL thickness in the worse hemisphere significantly correlated with the PD in the hemifield with visual field defects (r=0.418, p=0.047). The IRL thickness in the better hemisphere showed a weak correlation with the PD in the hemifiled without visual field defects (r=0.398, P=0.06).
Conclusions: :
The macular IRL thickness mapped by the FD-OCT associated significantly with visual field damages in glaucomatous eyes with hemifield defects. This suggests usefulness of the macular IRL mapping for diagnosing glaucomatous optic nerve damages.
Keywords: imaging/image analysis: clinical • nerve fiber layer