| Objective: To determine if there is any differences in visual field characteristics among chronic angle-closure glaucoma (CACG) , primary open angle glaucoma(POAG) and normal tension glaucoma(NTG).To evaluate the characteristic of the visual field defects in patients with CACG..Methods: Twenty-seven eyes of 27 CACG cases , 19 eyes of 19 NTG cases and 35 eyes of 35 POAG cases with early to moderately advanced visual field damagei which mean defect is smaller than 15 decibels (dB), were included. There were no significant difference in mean defect and age among the 3 groups. The visual field of each subject were measured by OCTOPUS 101 G2 program. Get rid of 1 point just in the comparison's center, divide the comparison chart into superior and inferior hemifields from 0° to 180° horizontal line, thus there are 29 points in superior or inferior hemifield, respectively. We input value of each point, which is the difference between the measured threshold and the age-corrected normal reference at each test point of the OCTOPUS 101 G2 program, in the comparison chart intocomputer as original data, and fix "+" as 0 dB and "■" as 32dB. We used the data above to calculate the value of mean defect (MD) and loss variance (LV) of the superior or inferior hemifield, and to determine any differences in the characteristics of hemifield mean defect among the three groups. The value of each test point was used for pointwise among the three groups. To discover if there are any differences in central 6?(9 points) visual field damage among the three groups, we evaluate the rate of central 6?visual field damage of each group. Patients had a central 6?visual field damage if they had at least: one of the 9 points depressed by at least 10 dB, or three adjacent points depressed by 5 dB. The results were analyzed.Results: The CACG cases and POAG cases had a significantly greater amount of MD in the superior hemifield than the inferior hemifield (P=0.024 and 0.010, respectively), but NTG cases had no statistically significant difference in the amount of MD between the superior and the inferior hemifield (P=0. 077). There were no statistically significant differences in the amount of LV in either superior or inferior hemif ield in CACG and NTG groups (P=0. 124 and 0. 481, respectively), however, the POAG cases had a significantly greater amount of LV in the superior hemifield than that in the inferior hemifield (P=0. 004). Expect 4 test points, there were no significant differences among the three groups at a majority of the 59 test points. There were no statistically significant differences in the amount of MD or LV in the superior or inferior hemifield among the three groups. There was found a significant difference in the number of patients with central visual field damage among the three groups. The NTG cases had the greatest rate of central visual field damage (57.9%), followed by POAG(54. 3%), and the central visual field of CACG is the least suffered (25.9%).Conclusion: Although there was no statistically significant difference in the amount of MD or LV in NTG between its superior hemifield and inferior hemifield, NTG cases had the greatest rate of central visual field damage than POAG and CACGcases. Comparison with the inferior hemifield, the superior hemifield of CACG had a greater amount of MD, and which central 6?visual field was least been damaged; POAG, as CACG, had a greater amount of superior hemifield MD, and also a greater amount of superior hemifield LV than its inferior hemifield. However, we found no statistically significant difference in the amount of MD or LV in the superior or inferior hemif ields among the three groups, which suggested there was some collective mechanism of optic nerve damage among the three groups.
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