[Comparative analysis of changes in the visual field in primary open-angle glaucoma and glaucoma with normal tension]

To compare the pattern and the depth of visual field defects of POAG and NTG patients.

The visual fields in two groups of POAG and NTG patients, each counting 25 eyes, were analysed statistically. All eyes were tested at least twice, employing full threshold G2 test of Octopus 101 (Interzeag) automatic perimeter. The tests with the highest reliability level were included. The analysis was performed using Peridata (Interzeag) statistical package. Mean values of mean defect (MD), corrected loss variance (CLV) and compound index (CI) for each group were acquired. Furthermore, main values of MD for upper and lower hemifield, quadrants and 10 degrees concentric rings, were obtained. The differences between the two groups were tested for the statistical significance.

Values of all three above parameters (MD, CLV i CI) were significantly lower in the group of eyes with POAG as compared with those with NTG. In both groups mean MD was higher in the upper hemifield, but the upper/lower hemifield ratio was significantly higher in the POAG group (1.50) as compared with NTG group (1.05). In POAG group the highest mean MD was found in the upper-temporal quadrant whereas in NTG group the lower-nasal quadrant was the most affected. In both groups the highest values of mean MD were found in the outer ring between 20 degrees and 30 degrees of visual field but the difference between the centre and periphery was considerably lower in NTG group.

The results support the opinion that there exist differences between the patterns of visual field changes in POAG and NTG. The loss tends to be more diffuse in POAG, showing deeper defects in the periphery and stronger tendency to affect the upper hemifield.