PURPOSE: To analyze the findings observed using the Humphrey Field Analyzer in patients with subtle visual field defects caused by chiasmal compression and study the best strategy for their detection. METHODS: Twelve patients with chiasmal compression were prospectively studied by manual and automated perimetry. Seventeen eyes with subtle defects on Goldmann perimetry were studied with the Humphrey Field Analizer, 24-2 threshold test. Analyzed items included: the gray scale drawing, the mean deviation, the number of missing points in the temporal as well as on the nasal hemi-field observed both on the total as well as on the pattern deviation. A mean deviation index was calculated using 12 points in the superior temporal quadrant and 12 points in the superior nasal quadrant. Findings from the nasal field were compared with those of the temporal field using Student's t test. RESULTS: Analysis of the gray scale pattern failed to identify the field defect in six eyes. Calculated superior temporal and nasal temporal mean deviation were respectivelly -9.65 ± 6.48 e -3.98 ± 2.30. Statistical analysis showed a significant difference between the two values. The mean number of missing points in the temporal hemifield observed on the total deviation was 11.64 ± 7.35 and in the nasal 8.11 ± 5.07. There was no significant difference between these data. On pattern deviation, the mean number of missing points in the temporal hemi-field was 5.82 ± 5.42 and in the nasal 2.41 ± 2.64. Statistical analysis showed significant differences between them. CONCLUSIONS: A simple analysis of the gray scale of visual fields fails to identify early defect from chiasmal compression in a significant number of patients. The observation of missing points on total deviation also seems to be insufficient to identify such field defects. The comparison between the mean deviation calculated in the nasal and temporal quadrants and the observation of a higher number of missing points in the temporal field compared to the nasal field on pattern deviation seem to be useful to detect such field defects.
Perimetry; Diagnostic techniques ophthalmological; Pituitary neoplasms
