Abstract
Purpose: :
To evaluate the ability of optical coherence tomography (OCT) to detect defects in patients with optic nerve head drusen (ONHD), in whom disc evaluations are often difficult.
Methods: :
14 patients (61.8 +/– 10.2 yrs) with ONHD and 17 control subjects (53.8 +/– 14.7 yrs) underwent a full ophthalmic examination including achromatic automated perimetry (AAP, SITA–Std 24–2), multifocal visual evoked potentials (mfVEP) and OCT [Fast RNFL (3.4)]. All ONHD were visible on clinical examination and/or by B–scan ultrasonography. For the mfVEP, the display was a "standard" pattern–reversal dartboard, which contained 60 sectors. The mfVEPs were analyzed with custom software. [1] Defects in the AAP total deviation plot and the mfVEP were defined, within a hemifield, as the presence of a cluster with > or = 3 spots with a P value of <5%, one of which had a P value of <1%, or 2 spots with a P value of <1%. In AAP, no more than 1 spot could fall on the rim of the plot. The OCT was considered abnormal if one of 5 sectors within a hemifield (the sectors at 3 and 9 o'clock were excluded) was at < 1% or two sectors at < 5%.
Results: :
The AAP mean deviations were –6.13 +/– 7.51 dB for the ONHD eyes and 0.26 +/– 0.80 dB for the control eyes. OCT detected a defect in 65% (34/52) of the hemifields, as compared to 54% (28/52) detected by AAP and 38% (20/52) detected by mfVEP. The OCT agreed with the AAP in 69% (36/52) of cases. When both the AAP and mfVEP were abnormal, OCT was abnormal in 94% (16/17) of the hemifields. When both were normal, OCT was abnormal in 48% (10/21). When the functional tests differed, OCT was abnormal in 57% (8/14). In controls, OCT showed a false positive rate of 1.7%.
Conclusions: :
The OCT detected a defect in more hemifields than did either AAP or mfVEP. While the OCT tended to be abnormal when both functional tests were abnormal, it was abnormal 48% of the time when both were normal and 51% when one or both of these tests were normal. Given the low false positive rate, it appears that OCT may be useful in detecting damage in patients with ONHD. 1. Hood & Greenstein, PRER, 2003.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • electrophysiology: clinical • visual fields