Purpose:
To investigate the role of OCT in differentiating between optic nerve head drusen and optic disk edema using both quantitative and qualitative measures.
Methods:
OCTs from 60 eyes of 60 patients (20 disk drusen, 20 disk edema, and 20 normal) were assessed quantitatively and qualitatively. The width of the hyporeflective space between the sensory retina and the retinal pigment epithelium/choriocapillaris complex on the OCT image was measured circumferentially at 30° spacing from a radius of 0.75mm, 1.5mm, and 2.0mm from the optic disk center (i.e., 36 total measurements, 12 for each radius from the disk). Qualitatively, 3 examiners, who were unaware of the diagnoses, viewed the OCT images and independently assessed the presence of optic disk edema, disk drusen, or normal optic nerve using morphologic characteristics on OCT (e.g., recumbent "V" sign, "lumpy bump" optic nerve head, etc.).
Results:
The mean hyporeflective space width was significantly different (See Table 1; *P<0.05) between disk edema and normal, and between disk edema and drusen at 0.75mm, 1.5mm, and 2.0mm; and between drusen and normal at 0.75mm and 1.5mm.The accuracy of differentiating disk edema, disk drusen, and normal optic nerve head using OCT morphology for the 3 examiners combined was 64.4% initial test and 70.0% at retest.
Conclusions:
Both disk edema and disk drusen are associated with increased thickening of the hyporeflective space within 1.5mm from the central optic disk. Increased thickness at 2.0mm was present only for disc edema. Qualitative assessment of the OCT morphology and quantitative evaluation of the thickness of the hyporeflective space on OCT may help clinicians more accurately and easily differentiate disk edema from disk drusen.
Keywords: optic nerve • neuro-ophthalmology: diagnosis • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)