Abstract
Purpose: :
to perform frequency doubling technology (FDT) perimetry in patients with pituitary tumors and subtle and moderate visual field (VF) defect on conventional perimetry, in order to evaluate its performance as a screening method of chiasmal compression.
Methods: :
Fifty one eyes (23 from 18 patients with pituitary tumors and 28 from 14 normal controls) were examined. Patients should have in at least one eye: visual acuity of 20/20 and mild or moderate temporal VF loss. On Goldmann perimetry, VF defect should be limited to the upper temporal field with I/3e, I/2e or I/1e targets. On automated perimetry mean deviations, calculated by averaging the most central upper temporal quadrant 12 points, should be scored as mild (–3.0 to –6.0 decibels) or moderate (–6.01 to –20.0 decibels). FDT testing was performed using the C–20–5 screening and the C–20 full–threshold test of an FDT device (Humphrey–Welch Allyn, Dublin, CA). Several criteria were used define abnormality for the screening as well as for the threshold test. Sensitivity and specificity was calculated for each criteria. Furthermore the number of missing points in each hemifield, the mean deviation and the mean value for sensitivity in each hemifield were calculated and compared between the two groups
Results: :
for the screening test sensitivity ranged from 21,74% (two abnormal adjacent points one < 5% and one < 1%) to 43,48% (two abnormal temporal points both < 5%) and specificity was 100% for all diagnostic criteria. For the threshold test sensitivity ranged from 52,17% (specificity of 85,71% for two abnormal adjacent points one < 5% and one < 1%) to 82,61% (specificity of 60,71% for two abnormal temporal points both < 5%) for the total deviation and from 30,43% (specificity of 96,42% for two abnormal adjacent points one < 5% and one < 1%) to 73,91% (specificity of 64,28% for two abnormal temporal points both < 5%) for the pattern deviation analysis. There was a significantly higher number of missing points in the temporal hemifield and on the temporo–nasal difference in missing points of patients both on the screening as well as in the full threshold test.
Conclusions: :
The screening test had a poor sensitivity but had a high specificity. The threshold test was very sensitive although less specific. FDT seems to be a promissing instrument for the detection of chiasmal compression.
Keywords: perimetry • neuro-ophthalmology: diagnosis • neuro-ophthalmology: optic nerve