Relationship between ocular perfusion pressure and retrobulbar blood flow in patients with glaucoma with progressive damage

PURPOSE: To evaluate the relationship between ocular perfusion pressure and color Doppler measurements in patients with glaucoma. MATERIALS AND METHODS: Twenty patients with primary open-angle glaucoma with visual field deterioration in spite of an intraocular pressure lowered below 21 mm Hg, 20 age-matched patients with glaucoma with stable visual fields, and 20 age-matched healthy controls were recruited. After a 20-minute rest in a supine position, intraocular pressure and color Doppler measurements parameters of the ophthalmic artery and the central retinal artery were obtained. Correlations between mean ocular perfusion pressure and color Doppler measurements parameters were determined. RESULTS: Patients with glaucoma showed a higher intraocular pressure (P <.0008) and a lower mean ocular perfusion pressure (P <.0045) compared with healthy subjects. Patients with deteriorating glaucoma showed a lower mean blood pressure (P =.033) and a lower end diastolic velocity in the central retinal artery (P =.0093) compared with normals. Mean ocular perfusion pressure correlated positively with end diastolic velocity in the ophthalmic artery (R = 0.66, P =.002) and central retinal artery (R = 0.74, P <.0001) and negatively with resistivity index in the ophthalmic artery (R = -0.70, P =.001) and central retinal artery (R = -0.62, P =.003) in patients with deteriorating glaucoma. Such correlations did not occur in patients with glaucoma with stable visual fields or in normal subjects. The correlations were statistically significantly different between the study groups (parallelism of regression lines in an analysis of covariance model) for end diastolic velocity (P =.001) and resistivity index (P =.0001) in the ophthalmic artery, as well as for end diastolic velocity (P =.0009) and resistivity index (P =. 001) in the central retinal artery. CONCLUSIONS: The present findings suggest that alterations in ocular blood flow regulation may contribute to the progression in glaucomatous damage.     

Topical treatment for 1 week with latanoprost but not diclofenac reduces the diameter of dilated retinal arterioles in patients with type 1 diabetes mellitus and mild retinopathy

Purpose: Diabetic retinopathy is characterised by morphological lesions secondary to retinal vascular impairment, and it is assumed that changes in the diameter regulation of retinal arterioles are involved in the disease pathogenesis. It has previously been shown that prostaglandin F2α can constrict retinal arterioles in vitro. In the present study, we investigated whether a similar effect could be achieved by topical administration in diabetic patients with dilated retinal arterioles and retinopathy. Methods: Twenty‐two type 1 diabetic patients with mild retinopathy and twenty‐four matched normal controls were randomized to topical treatment with the prostaglandin F2α agonist latanoprost twice daily for 1 week, followed by similar treatment with the cyclo‐oxygenase inhibitor diclofenac, or to receive the two medications in the reverse order. The Dynamic Vessel Analyzer was used to assess the effect of the interventions on the resting diameter of retinal vessels and on the diameter response of retinal arterioles to increased blood pressure (BP) induced by isometric exercise and flicker stimulation. Results: Latanoprost reduced the resting diameter of retinal arterioles significantly in patients with diabetes (p = 0.01), but had no effect on normal persons. Diclofenac had no effect on the resting diameter of arterioles in either of the groups. The diameter responses to increased BP and flicker stimulation were not significantly changed by any of the treatments. Conclusion: Long‐term prospective studies are needed to study the effect of topical treatment with latanoprost on the consequences of retinal hyperperfusion in retinal vascular diseases such as diabetic retinopathy.     

The interaction between intracranial pressure,intraocular pressure and lamina cribrosal compression in glaucoma

This review examines some of the biomechanical consequences associated with the opposing intraocular and intracranial forces. These forces compress the lamina cribrosa and are a potential source of glaucomatous pathology. A difference between them creates a displacement force on the lamina cribrosa. Increasing intraocular pressure and/or decreasing intracranial pressure will increase the trans‐lamina cribrosa pressure difference and the risk of its posterior displacement, canal expansion and the formation of pathological cupping. Both intraocular pressure and intracranial pressure can be elevated during a Valsalva manoeuvre with associated increases in both anterior and posterior lamina cribrosa loading as well as its compression. Any resulting thinning of or damage to the lamina cribrosa and/or retinal ganglion cell axons and/or astrocyte and glial cells attached to the matrix of the lamina cribrosa and/or reduction in blood flow to the lamina cribrosa may contribute to glaucomatous neuropathy. Thinning of the lamina cribrosa reduces its stiffness and increases the risk of its posterior displacement. Optic nerve head posterior displacement warrants medical or surgical lowering of intraocular pressure; however, compared to intraocular pressure, the trans‐lamina cribrosa pressure difference may be more important in pressure‐related pathology of the optic nerve head region. Similarly important could be increased compression loading of the lamina cribrosa. Reducing participation in activities which elevate intraocular and intracranial pressure will decrease lamina cribrosa compression exposure and may contribute to glaucoma management and may have prognostic significance for glaucoma suspects.     

The association of ocular blood flow with haemorheological parameters in primary open‐angle and exfoliative glaucoma

Purpose: To evaluate the ocular blood flow velocities and haemorheological parameters in patients with primary open‐angle glaucoma (POAG), exfoliative glaucoma (XFG) and exfoliation syndrome (XFS) and to compare their results with those of healthy controls. Methods: Twenty‐five patients with POAG (group 1), 25 patients with XFG (group 2), 25 patients with XFS (group 3) and 25 healthy controls (group 4) were included in the study. Ocular blood flow velocities of ophthalmic artery (OA), central retinal artery (CRA) and short posterior ciliary arteries (SPCAs) were measured using colour Doppler imaging (CDI). Haemorheological parameters (erythrocyte elongation and aggregation index, aggregation amplitude, aggregation half‐life, plasma viscosity, haematocrit) were measured in venous blood samples of all patients. Results: The peak systolic velocity (PSV) and end‐diastolic velocity (EDV) values were lower and resistive indices (RI) were higher for the OA, CRA and SPCA of glaucomatous (groups 1 and 2) patients compared with those of controls (group 4) (PSV: OA, 40.4 ± 11.3 versus 52.6 ± 12.8 cm/second, p < 0.001; CRA, 12.9 ± 2.9 versus 15.3 ± 4.2 cm/second, p = 0.02; SPCA, 21.7 ± 6.6 versus 26.6 ± 8.3 cm/second, p = 0.013) (EDV: OA, 10.3 ± 4.3 versus 14.2 ± 5.1 cm/second, p < 0.001; CRA, 3.7 ± 1.1 versus 4.5 ± 1.3 cm/second, p = 0.025; SPCA, 5.2 ± 1.8 versus 7.7 ± 3.2 cm/second, p = 0.001) (RI: OA, 0.75 ± 0.05 versus 0.66 ± 0.07, p < 0.001; CRA, 0.73 ± 0.08 versus 0.68 ± 0.10, p = 0.223; SPCA, 0.70 ± 0.10 versus 0.63 ± 0.11, p = 0.004). There were no statistically significant differences between the haemorheological parameters of glaucomatous and non‐glaucomatous patients. The reduction in ocular blood flow velocities in groups 1, 2 and 3 were not associated with changes in haemorheological parameters. Conclusion: Our results suggest that impairment of the retrobulbar blood flow in POAG and XFG is not associated with alterations in haemorheological parameters.     

拉坦前列素联合噻吗心安对开角型青光眼视觉功能、眼压、眼血流的影响

目的：：研究拉坦前列素联合噻吗心安治疗方案对开角型青光眼视觉功能、眼压、眼血流的影响。方法：将2012-01/2014-05期间在我院眼科收治的开角型青光眼患者50例59眼纳入研究对象,采用数字表法随机分为观察组和对照组,观察组患者给予拉坦前列素联合噻吗心安治疗,对照组患者给予噻吗心安治疗,比较两组患者的视觉功能、眼压、眼血流情况。结果：治疗后1,2,3,4wk,观察组患眼白天平均眼压、夜间平均眼压均明显低于对照组,视力水平(0.27±0.03,0.36±0.06,0.44±0.06,0.63±0.13)明显高于对照组;观察组患眼的收缩期峰值血流速度(14.41±1.73cm/s)、舒张末期血流速度(4.18±0.67cm/s)均明显高于对照组,血管阻力指数(0.58±0.07)明显低于对照组。结论：拉坦前列素联合噻吗心安能够更为有效降低眼压,增加视网膜中央动脉的血流量,降低血管阻力,改善视力水平。     

原发性开角型青光眼眼动脉,视网膜中央动脉血流速度与血液粘度的关系

本文分析了原发性开角青光眼７４只眼眼动脉和视网膜中央动脉血流速度的关系，结果表明眼动脉收缩最大血流速度与血液度无相关关系，舒张末期血流速度与血浆粘度有关；视网膜中央动脉收缩了大血流速度和舒张末期血流速度和低切变率下全血表观粘度密切相关。提示视网膜动脉血流速度受血液粘度影响较大。     

The effects of moxaverine on ocular blood flow in patients with age‐related macular degeneration or primary open angle glaucoma and in healthy control subjects

Purpose: The phosphodiesterase inhibitor moxaverine has been shown to increase choroidal blood flow (BF) in young healthy subjects. The present study was performed to investigate the effect of intravenously administered moxaverine on ocular BF in patients with age‐related macular degeneration (AMD), primary open angle glaucoma (POAG) and in age‐matched control subjects. Methods: Twenty patients with AMD, 20 patients with POAG and 20 control subjects were included. Moxaverine 150 mg was applied intravenously over 30 min. BF was measured in the choroid and in the optic nerve head (ONH) using laser‐Doppler flowmetry and in retinal vessels combining laser‐Doppler velocimetry with retinal vessel analysis before and 30, 60 and 90 min after start of drug administration. BF velocities in the retrobulbar vessels were measured using colour Doppler imaging. Results: Moxaverine increased choroidal BF by 9 ± 22% (p = 0.012), ONH BF by 13 ± 33% (p = 0.021), mean flow velocity in the ophthalmic artery by 23 ± 34% (p < 0.001) and in the posterior ciliary arteries by 25 ± 35% (p < 0.001). Moxaverine had no significant effect on retinal vessel diameters and retinal BF. There were no significant differences in any of the measured parameters between the three groups. Conclusion: The present study indicates that systemic administration of moxaverine increases choroidal and ONH BF in elderly patients with eye diseases associated with hypoperfusion and in age‐matched controls. Further studies in patients are needed to investigate whether long‐term treatment with moxaverine is clinically beneficial for patients with ocular diseases.