97th DOG Annual Meeting 1999
EFFECT OF CARBON DIOXIDE ON VISUAL FUNCTION IN NORMAL
PRESSURE AND HIGH PRESSURE GLAUCOMA
A. G. Böhm, A. U. Koeller, L. E. Pillunat
Purpose: It was previously shown that a provoked vasodilation (calcium channel blockers, carbon dioxide) improves ocular hemodynamics in normal pressure glaucoma patients. In an attempt to evaluate the effect of vasodilation on visual function, 23 normal pressure glaucoma patients and 204 patients suffering from high pressure glaucoma (HPG) were examined.
Methods: The Carbogen-test (95 % O2 and 5 % CO2 in a partly closed rebreathing system) was used to provoke vasodilation during visual field testing (Humphrey 30-2-visual fields). One randomly choosen eye of visual field-experienced patients was choosen and a visual field under room air condition or under the carbogen-condition was performed in a random sequence. 204 patients suffering from primary high pressure glaucoma (age = 66 years, 110 female, 94 male) and 23 patients with normal pressure glaucoma (age 62 years, 14 female, 9 male) were included in the study. A change of the visual field exceeding the actual short time fluctuation was regarded as a positive response to provoked vasodilation. For statistical analysis the Mann-Whitney-U-Test was used.
Results: The visual field of 49 patients (24 %) suffering from primary open angle glaucoma improved significantly (p < 0,001) during carbogen breathing (MD-Baseline x =-13,52; MD-visual field (MD-Baseline: x = -13,21; MD-Carbogen: x = -13,68). In the normal pressure glaucoma group there was found a visual field improvement in 8 (35 %) out of 23 patients. In these patients the MD improved from -13,49 to -3,79 dB (p < 0,01) whereas the other normal pressure glaucoma patients did not show any significant changes of their visual field (MD-Baseline: x = -13,58; MD-Carbogen: x = -13,19 dB).
Conclusion: The results presented, demonstrate some evidence that a subgroup of normal pressure glaucoma patients (35%) but also of high pressure glaucoma patients (24%) suffer from an ocular vasospasm which is released by carbogen breathing.
University Eye Hospital Hamburg, Martinistr. 52, D-20246 Hamburg