Relationship Between Optic Nerve Head Drusen Volume and Structural and Functional Optic Nerve Damage

Abstract

Purpose: 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)] mm. Linear and quadratic regression analyses demonstrated that ONHD volume is significantly associated with both global average RNFL thickness (linear R=0.531, quadratic R=0.557; P<0.001) and VF mean deviation (linear R=0.519, quadratic R=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.