Artikel
Local retinal arterial reaction to moderate artificial reduction of perfusion pressure in normals and glaucoma patients
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Autoren
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K. E. Kotliar
- Department of Ophthalmology, Munich University of Technology
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E. Nagel
- Eye Consultant Rudolstadt
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W. Vilser
- Biomedical Engineering, Ilmenau University of Technology
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I. M. Lanzl
- Department of Ophthalmology, Munich University of Technology
| Veröffentlicht: | 22. September 2004 |
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Gliederung
Text
Objective
Whether the local reaction to moderate artificial IOP increase in retinal branch arteries differs between healthy subjects and glaucoma patients is investigated with Retinal Vessel Analyzer (RVA).
Methods
14 untreated primary open angle glaucoma patients (61,2±7,6 years old, IOP: 22,4±6,0 mmHg) and 13 age matched normal volunteers (62,6±6,7 years old, IOP: 13,8±2,9 mmHg) were examined. Baseline RVA measurement was performed for 2 minutes. IOP was then moderately artificially increased for 100 s by suction cup and then released. The IOP increase amounted to 21,2±3,5 mmHg in normals and to 16,5±2,4 mmHg in glaucoma patients by equal experimental design. After the provocation the measurements were continued for further 10 minutes. Changes in vessel diameter of branch retinal arteries were assessed along a 1,5 mm long segment. The characteristic parameters of local vessel behavior were analyzed mathematically and statistically.
Results
No significant difference was found in spectral edge frequency of the power spectrum (SEF) between baseline measurements in normal volunteers (0,102±0,036 MU-1 and glaucoma patients (0,100±0,041 MU-1) (p>0,3). In the dilation phase no statistically significant difference in SEF between normals (0,134±0,039 MU-1) and glaucoma patients (0,119±0,045 MU-1; p>0,2) was found. SEF values did also not differ significantly between the groups during the reactive constriction phase after the provocation (p>0,3): normals: 0,114±0,026 MU-1; glaucoma: 0,103±0,039 MU-1.
Conclusions
We termed the frequency in amplitude change of vessel width "vessel thickness change frequency" (VTCF). As a characteristic description for this parameter we employed the SEF of local retinal vessel diameters. In the present study we did not find any significant difference in VTCF between normals and glaucoma patients. In an earlier study with short-term suprasystolic IOP provocation VTCF was significantly less in normals than in glaucoma patients during dilation phase in arteries. One can speculate therefore, that moderate IOP-peaks in normals as well as in glaucoma patients can be compensated by retinal vascular autoregulative mechanisms. However extreme IOP-peaks in glaucoma cannot be completely compensated by vascular regulation.
