OPTIC CHIASM WIDTH IN NORMAL-TENSION AND HIGH-TENSION GLAUCOMA.

Abstract

The aim of our study was to find out whether in patients with hypertensive glaucoma (HTG) and normotensive glaucoma (NTG), there is achange in the size of the chiasm depending on the changes in the visual field. Therefore, we retrospectively measured the width of the chiasm in the patients to whom we measured the size of the corpus geniculatum laterale in 2013. The group consisted of two groups of patients. Nine with hypertensive glaucoma (HTG) and nine with normotensive glaucoma (NTG). The diagnosis was based on acomplex ophthalmological examination and in NTG and electrophysiological examination. The visual field was examined by arapid threshold program on the Medmont M700. The sum of the sensitivity from both visual fields in the range of 0-22 degrees was compared with the width of the chiasm obtained by the magnetic resonance imaging using the eight channel head coil. The measured values of all subjects were analyzed using apaired t-test and acorrelation coefficient. We found areduction in the chiasma width in both glaucoma groups. We found astatistically significant difference in the size of the chiasm (p=0.0003) between the control group and the HTG group (p=0.001). The narrowing of the chiasm showed aslight correlation in HTG with changes in the field of vision (r=0.139) and in NTG amoderate correlation (r=0.375). We found areduction in the size of the chiasm in both HTG and NTG. The sum of sensitivities in the central parts of the visual field, however, more correlated with the reduction in the size of the chiasm in NTG. This finding shows that there are two different diagnostic groups.