Relationship Between Optic Nerve Head Drusen Volume and Structural and Functional Optic Nerve Damage
The purpose of this study is to assess the relationships between optic nerve head drusen (ONHD) volume, retinal nerve fiber layer (RNFL) thickness and visual field (VF) loss.Methods:
Patients with ONHD and no other ocular or systemic conditions that can affect RNFL or VF were enrolled. Serial enhanced depth imaging (EDI) optical coherence tomography (OCT) B-scans of the optic nerve head (interval between scans, ~30 μm) were obtained from each participant. ONHD volume was calculated for each eye by delineating the ONHD masses in each OCT B-scan using 3-dimensional reconstruction software.Results:
A total of 47 eyes (28 patients) with ONHD were included (mean age, 57±16 y). ONHD volume varied considerably [0.265±0.227 (range, 0.005 to 0.855)] mm3. Linear and quadratic regression analyses demonstrated that ONHD volume is significantly associated with both global average RNFL thickness (linear R2=0.531, quadratic R2=0.557; P<0.001) and VF mean deviation (linear R2=0.519, quadratic R2=0.522; P<0.001). ONHD were most prevalent in the nasal quadrant (46 eyes, 98%), followed by superior, inferior and temporal quadrants [35 (74%), 30 (64%), and 16 (34%) eyes respectively]. The proportion of eyes with OCT RNFL defects (81%; 38/47 eyes) was significantly greater than that with VF defects (60%; 28/47 eyes) (P<0.001). RNFL defects were detected in 10 of the 19 eyes with no VF defects. RNFL defects were detected in all 28 eyes with VF defects.Conclusions:
ONHD volume generally correlates with structural and functional optic nerve damage.