Compromised autoregulatory control of ocular hemodynamics in glaucoma patients after postural change.

PURPOSE: The autoregulatory control of retrobulbar blood flow in response to postural challenge was investigated in normal-tension glaucoma (NTG) patients in comparison with primary open-angle glaucoma (POAG) patients and healthy volunteers. DESIGN: Prospective cohort study. PARTICIPANTS AND CONTROLS: Twenty POAG patients, 20 NTG patients, and 20 control subjects. METHODS: Peak systolic velocity (PSV), end diastolic velocity (EDV), and resistivity index (RI) in the short posterior ciliary artery (SPCA), central retinal artery (CRA) and ophthalmic artery (OA) were recorded after a change from sitting upright to a supine body position using color Doppler imaging. MAIN OUTCOME MEASURES: Peak systolic velocity, EDV, and RI. RESULTS: Ten minutes after postural change to a supine position, blood flow velocities in the SPCA remained unchanged in controls, whereas a significant increase of PSV and EDV was found in both glaucoma groups. The RI in the SPCA was significantly lowered in the NTG group. Recordings for the OA and CRA showed a significant increase in EDV and significant decrease in RI in all 3 groups; a significant increase in PSV in the CRA was detected only in the NTG group. CONCLUSIONS: The unaltered flow velocities in the SPCA of healthy controls may indicate tight autoregulatory control, whereas the flow velocities in the CRA and OA appeared to follow alterations in hydrostatic pressure. In contrast, NTG and POAG patients demonstrated an insufficient compensatory response to postural change, leading to accelerated flow in the SPCA. This compromised autoregulatory control could represent another contributing factor in the pathogenesis of glaucoma.

Effects of glaucoma drugs on ocular hemodynamics in normal tension glaucoma: a randomized trial comparing bimatoprost and latanoprost with dorzolamide [ISRCTN18873428].

BACKGROUND: Reduced choroidal perfusion is hypothesized to play a role in the pathogenesis of normal tension glaucoma. Thus the impact of antiglaucomatous eye drops on ocular perfusion has been the focus of recent research and the subject of intensive investigations. The present study investigates whether topically applied latanoprost or bimatoprost influence ocular perfusion in patients with normal tension glaucoma and compares these effects with that changes detected after the treatment with dorzolamide. METHODS: Ocular hemodynamics were assessed by color Doppler imaging (CDI) shortly before and after a one-month treatment with either latanoprost, bimatoprost or dorzolamide. Primary end-points of the study were peak systolic and end-diastolic blood flow velocities in the short posterior ciliary artery (SPCA) under the new therapy. Intraocular pressure (IOP) and additional perfusion parameters in the SPCA and other retrobulbar vessels were tracked as observational parameters. n = 42 patients with normal tension glaucoma were enrolled in the study. RESULTS: Systolic and diastolic blood flow velocities in the SPCA showed no significant alteration after the treatment with latanoprost or bimatoprost. Dorzolamide lead to increase of peak systolic velocity. IOP was reduced by all three agents in a range reported in the literature. CONCLUSION: Topically applied latanoprost and bimatoprost act in a hemodynamically neutral manner and have the capability to lower IOP even in patients with normal tension glaucoma and low initial IOP level. Dorzolamide accelerates blood flow in systole. None of the tested compounds has a negative impact on hemodynamics in the short posterior ciliary arteries.

Estimation of choroid perfusion by colour Doppler imaging vs. other methods.

Ocular haemodynamics play a prominent role in several ocular diseases. Recently, new methods for the determination of ocular perfusion were developed. Colour Doppler imaging (CDI) of orbital vessels has come up in the past decade and was shown to be useful in ophthalmological diagnostics. Little is known about measurement of choroid perfusion by CDI in comparison with other methods. Therefore, 49 eyes were examined with CDI, laser Doppler flowmetry (LDF) and the method of Langham (LOBF). Correlations between the methods were identified by the Spearman correlation coefficient (r). LDF readings correlated with time-averaged mean velocity assessed by CDI in the long posterior ciliary artery (r = 0.47; p = 0.039; n = 20), but not in the short posterior ciliary artery. LOBF measurements correlated with pulsatility index (PI) of CDI in short (r = 0.50; p = 0.005; n = 30) and long posterior ciliary arteries (r = 0.41; p = 0.024; n = 30). Methods strengthened each other by partial correlation. The study demonstrates that CDI allows a more detailed insight into ocular perfusion.

[Estimation of ocular perfusion: a practical oriented comparison of different methods]. / Abschätzung der okulären Perfusion: Ein praxisorientierter Vergleich aktueller Methoden.

BACKGROUND: Ocular haemodynamics play a prominent part in many ocular diseases. This leads to the need to determine ocular perfusion. Several studies reveal advantages of colour Doppler imaging (CDI) in ophthalmologic diagnostics. Little is known about correlation of CDI results with other methods. PATIENTS AND METHODS: N = 56 eyes were examined with CDI, laser Doppler flowmetry (LDF) and Langham-OBF (LOBF). Correlations between the methods were identified by the Spearman correlation coefficient (R). RESULTS: LDF correlated with time average maximum (TAMx) and mean (TAMn) velocity assessed by CDI in the long posterior ciliary artery (TAMx: R = 0.466, p = 0.038, n = 20; TAMn: R = 0.462; p = 0.040, n = 20), but not in the short posterior ciliary artery. LOBF correlated with pulsatility index (PI) and resistive index (RI) of CDI in short (PI: R = 0.514, p = 0.002, n = 35; RI: R = 0.438, p = 0.008, n = 35) and long posterior ciliary arteries (PI: R = 0.436, p = 0.009, n = 35; RI: R = 0.506, p = 0.002, n = 35). DISCUSSION: Methods strengthen each other by partial correlation. CDI allows a more detailed insight into ocular perfusion than the other methods.

[Therapy of normal tension glaucoma: effect of brinzolamide on ocular haemodynamics]. / Therapie des Normaldruckglaukoms: Hämodynamische Effekte von Brinzolamid am Auge.

BACKGROUND: Altered ocular perfusion plays a role in the pathophysiology of normal tension glaucoma. Dorzolamide, a locally applied inhibitor of carbonic anhydrase, is thought to increase ocular blood flow. Less data are available regarding the influence exercised on ocular perfusion by brinzolamide, another and different, locally administered, inhibitor of carbonic anhydrase. PATIENTS AND METHODS: n = 15 eyes of 8 normal tension glaucoma patients were subjected to colour Doppler imaging and Langham-OBF (LOBF) before and during a therapy for 3 - 5 weeks with brinzolamide. RESULTS: Brinzolamide reduces intraocular pressure from 15.8 +/- 0.9 to 12.6 +/- 0.9 mm Hg (n = 15; P < 0.05). Systolic as well as diastolic blood flow velocities, resistive (RI) and pulsatility index (PI), measured by CDI, remained unchanged in the presence of brinzolamide. LOBF values are also not influenced by brinzolamide (1014 + 115 before vs. 1113 +/- 178 microl under therapy; n = 15; n. s.). DISCUSSION: Brinzolamide does not exercise any impact on ocular haemodynamics. This is different from the properties of dorzolamide that had been reported previously.