Augeninnendruckmessungen im Tages- und Nachtverlauf bei Glaukompatienten und Normalprobanden mittels Goldmann- und Perkins-Applanationstonometrie

OBJECTIVE

Our aim was to evaluate intraocular pressure (IOP) levels in primary open angle glaucoma (POAG) patients and healthy controls during both the day and night while measuring in an upright as well as in a supine position.

METHODS

In a prospective clinical trial, 30 glaucoma patients on topical treatment and 50 healthy controls received IOP measurements every 4 h for a 24 h period starting at 8 am. Additionally, blood pressure and heart rate were measured and perfusion pressures were calculated. At 12 am IOP was initially measured in a sitting position and then, after 20 min, in a supine position. At midnight this was carried out conversely. At 4 am IOP was measured in a supine position; all other measurements were performed in a sitting position. Measurements in the sitting position were performed by Goldmann and Perkins tonometry and in a supine position by Perkins tonometry.

RESULTS

IOP was 1 mmHg lower in Perkins tonometry measurements compared to Goldmann tonometry. There was no difference between the two patient groups. In a supine position, IOP measured by Perkins tonometry was higher than in an upright position. At 12 am the difference was 1.8 mmHg+/-2.7 mmHg (p=0.001) in healthy subjects and 1.3+/-2.7 mmHg (p=0.013) in the POAG patients. At 12 pm the increase of IOP in the supine position was even more pronounced with 2.4+/-3.4 mmHg in healthy subjects and 5.6+/-3.2 mmHg in the POAG patients (p=0.001). The blood pressure and the perfusion pressure were lowest during night measurements.

CONCLUSIONS

During diurnal IOP measurements in an upright position there were no statistically significant differences in IOP changes between groups. However, in a supine position IOP was significantly higher than in a sitting position and increased more in the glaucoma patients than in healthy controls. This observation might be due to a faulty regulation of the fluid shift in glaucoma patients and could cause progression of glaucomatous damage.

[Papillary hemodynamics in patients with normal pressure glaucoma and hemorrhage of the optic papilla circumference]

BACKGROUND

Optic disc hemorrhages in patients with normal-pressure glaucoma (NPG) are usually regarded as a sign of vascular dysfunction and as an indicator for glaucoma damage progression.

METHODS

Optic nerve head blood flow was measured in 21 patients suffering from NPG with acute optic disc hemorrhages by scanning laser Doppler flowmetry at various locations of the optic disc. Intraocular pressure and mean deviation of the visual field were also monitored. Two groups served as control: 21 patients with NPG matched for age, sex, and stage of the disease and in addition the contralateral eye without any hemorrhages.

RESULTS

Optic nerve head blood flow as a mean of several locations was significantly lower in eyes with optic disc hemorrhages than in controls and differed significantly from the contralateral eye.

CONCLUSION

Optic nerve blood flow was lower in NPG eyes with optic disc hemorrhages than in the contralateral eye and in controls.

Effect of topical dorzolamide on optic nerve head blood flow

PURPOSE

The topical carbonic anhydrase inhibitor dorzolamide has proven effective in lowering intraocular pressure in glaucoma patients. Because an impaired blood supply of the optic nerve has to be regarded as a major pathogenic risk factor it seems important to examine the effect of this new antiglaucomatous drug on capillary optic nerve head blood flow.

METHODS

In a double-masked, randomized clinical trial, dorzolamide eye drops were applied to both eyes of 15 healthy subjects (8 female, 7 male, mean age 30.6 years) three times daily for 3 days. The control group (15 healthy volunteers, 9 female, 6 male, mean age 30.8 years) received a placebo preparation according to the same protocol. Intraocular pressure (IOP), blood pressure, heart rate, capillary optic nerve head blood flow and retinal blood flow were measured at baseline (1D0), 90 min after single instillation (1D90), and after 3 days of therapy (3D). Scanning laser Doppler flowmetry (Heidelberg Retina Flowmeter) and laser Doppler flowmetry according to Riva (Oculix 4000) were used to measure optic nerve head blood flow.

RESULTS

IOP dropped in dorzolamide-treated subjects from 12.5 mmHg to 11.0/10.5 mmHg (1D0, 1D90, 3DO) and in the control group from 13.0 mmHg to 12.5/12.5 mmHg. Optic nerve blood flow as measured by scanning laser Doppler flowmetry showed no significant changes in dorzolamide-treated volunteers (temporal 310/329/315 AU, nasal 387/402/399 AU) or in the placebo group (temporal 238/306/276 AU, nasal 356/382/379 AU). Also as measured by laser Doppler flowmetry optic nerve head blood flow did not show significant changes in dorzolamide-treated volunteers (temporal 12.98/12.6/11.7 AU, nasal 16.6/16.9/15.7 AU) or in the placebo group (temporal 11.9/12.4/12.4 AU, nasal 16.1/15.8/17.7 AU). The systemic parameters blood pressure and heart rate remained unchanged during the treatment period.

CONCLUSION

The results showed the expected drop in IOP. However, capillary optic nerve head blood flow, measured by two different techniques, did not change during therapy. This may be due to the effective autoregulation in human optic nerve head circulation, which seems not to be affected by dorzolamide.