Anatomical and functional impairment of the nerve fiber layer in patients with optic nerve head drusen

Objective To evaluate anatomical and functional impairment of the retinal nerve fiber layer (RNFL) using optical coherence tomography (OCT) and automated perimetry in patients with optic nerve head drusen (ONHD). Materials and methods Sixty-six eyes (66 patients) were studied with ONHD — confirmed by ultrasound B scan — and 70 eyes (70 subjects) of healthy control subjects. ONHD cases were categorised as visible or hidden. Average RNFL thickness and measurements in terms of the quadrants were analysed using both time-domain optical coherence tomography (TD-OCT) and spectral-domain optical coherence tomography (SD-OCT). Anatomical and visual field alteration of RNFL between visible and hidden ONHD and control groups were compared. Results Average RNFL thickness in ONHD patients was 94 μm (TD-OCT) and 88 μm (SD-OCT), and in controls 107 μm (TD-OCT) and 96 μm (SD-OCT), with statistically significant differences between both OCTs. All quadrants analysed showed significant differences except the temporal quadrant. The differences were not significant between hidden drusen and controls.Visual field examination in ONHD showed alterations in 56 %. Alterations were greater in visible drusen in relation to non-visible drusen, but there were no significant differences.The association between RNFL defects in superior, inferior and temporal quadrants and visual field defects showed a statistical relation with visible ONHD, but not in hidden ONHD. Conclusions ONHD caused anatomical and functional damage of the RNFL, with a clear association between the alteration in ONHD and visual field defects in visible drusen cases.