Short-Term Effects of Ginkgo biloba Extract on Peripapillary Retinal Blood Flow in Normal Tension Glaucoma

PURPOSE: Based on the vascular theory of glaucoma pathogenesis, we wanted to evaluate the effect of Ginkgo biloba extract (GBE) on peripapillary blood flow in patients with normal tension glaucoma (NTG). METHODS: Thirty patients with NTG were randomly placed in the GBE-treated or control groups. The GBE-treated group received 80 mg GBE orally, twice a day for four weeks, and the control group received a placebo twice a day for four weeks. Complete ocular examinations including visual field, Heidelberg retina flowmeter, and systemic examinations were performed on the first study day and on the day treatment was completed. RESULTS: After GBE treatment, the mean blood flow, volume, and velocity increased at almost all points, and there was a statistically significant increase in blood flow at almost all points, in comparison to the placebo. Blood volume significantly increased only in the superior nasal and superior temporal neuroretinal rim areas. GBE also significantly increased blood velocity in areas of the inferior temporal neuroretinal rim and superior temporal peripapillary area. CONCLUSIONS: GBE administration appears to have desirable effect on ocular blood flow in NTG patients.

Short-Term Effects of Ginkgo biloba Extract on Peripapillary Retinal Blood Flow in Normal Tension Glaucoma

PURPOSE: Based on the vascular theory of glaucoma pathogenesis, we wanted to evaluate the effect of Ginkgo biloba extract (GBE) on peripapillary blood flow in patients with normal tension glaucoma (NTG). METHODS: Thirty patients with NTG were randomly placed in the GBE-treated or control groups. The GBE-treated group received 80 mg GBE orally, twice a day for four weeks, and the control group received a placebo twice a day for four weeks. Complete ocular examinations including visual field, Heidelberg retina flowmeter, and systemic examinations were performed on the first study day and on the day treatment was completed. RESULTS: After GBE treatment, the mean blood flow, volume, and velocity increased at almost all points, and there was a statistically significant increase in blood flow at almost all points, in comparison to the placebo. Blood volume significantly increased only in the superior nasal and superior temporal neuroretinal rim areas. GBE also significantly increased blood velocity in areas of the inferior temporal neuroretinal rim and superior temporal peripapillary area. CONCLUSIONS: GBE administration appears to have desirable effect on ocular blood flow in NTG patients.

Macular Hemodynamics before and after Retinal Photocoagulation in Branch Retinal Vein Occlusion using Heidelberg Retina Flow meter(HRF )

To investigate the pathogenesis of macular edema in branch retinal vein occlusion(BRVO)and its attributing factors, we measured the macular circulation using HRF(Heidelberg Retina Flowmeter)before, 1 hour, 1 day, and 1 month after grid laser photocoagulation in 12 patients. After laser photocoagulation, the macula circulation significantly increased in 8 eyes(group 1), and remained unchanged in 4 eyes(group 2). Mean postoperative macular circulation of group 1 was blood volume 136.2%, blood flow 148.0%, and blood velocity 144.4%. And mean postoperative macular circulation of group 2 was blood volume 103.8%, blood flow 97.8%, and blood velocity 98.8%. The mean age of the patient was higher in group 1(group1:mean age 59.0, group 2:mean age 43.5, p=0.0008)and the interval between the onset of BRVO and photocoagulation was longer in group 1 than in group 2(group 1:12.4 months, group 2:4.3 months, p=0.0233). Our results suggest that retinal autoregulation may play an important role in the resolution of macular edema in BRVO after grid photocoagulation. Therefore the evaluation of retinal autoregulation using HRF is important in determining the treatment guide line and the prognosis of photocoagulation.

The Effects of Pa n retinal Photocoagulation on Macular Microcirculation in Diabetic Retinopathy(Short term follow up)

We investigated the effects of panretinal photocoagulation (PRP)on macular microcirculation in diabetic retinopathy. PRP using argon blue green laser was performed in 23 eyes of 15 patients with early proliferative diabetic etinopathy and very severe nonproliferative diabetic retinopathy without significant macular edema. The changes in volume, flow, velocity of macular microcirculation were measured before PRP, 1 hour, 1 day, 1 week, and 1 month following PRP, using Heidelberg Retina Flowmeter(HRF). Mean volume, flow, velocity of macular microcirculation decreased to a maximal degree 1 hour following PRP, from 14.87+/-0.40, 387.45 +/-101.40, 1.40+/-0.28(before PRP)to 12.44+/-1.39, 347. 33+/-100.39, 1.27+/-0.34(p<0.05). From 1hour to 1 month after PRP, macular microcirculation gradually increased. However, throughout this period, all parameters of macular microcirculation remained lower than pre-PRP level(p<0.05). Our study suggests that panretinal photocoagulation reduces the macular microcirculation in diabetic retinopathy.

The Effect of Hyperoxia on the Retinal and Optic Nerve Head Microcirculation in Smoke rs and Non-Smokers

The effect of hyperoxia and smoking on retinal and optic nerve head microcirculation, and O2 reactivity in smokers and non-smokers were investigated using HRF(Heidelberg Retinal Flowmeter). 10 eyes of 10 young healthy non-smoking volunteers and 10 eyes of 10 young healthy smoking volunteers were investigated. Blood flow measurements were performed using HRF before and after 100% oxygen was applied to the subjects. In the non-smoking group, retinal flow was reduced by 33%, retinal volume by 24%, optic nerve head flow by 16% and optic nerve head volume by 18%. In the smoking group, retinal flow was reduced by 19%, retinal volume by 16%, optic nerve head flow by 16% and optic nerve head volume by 16%. The difference of O 2 reactivity between smokers and non-smokers was statistically significant in the retinal blood flow and volume, but not significant in the optic nerve head flow and volume. These results indicate that hyperoxia leads to a decrease in capillary blood flow of the retina and optic nerve head secondary to vasoconstriction, and that smoking decreases O2 reactivity in retinal microcirculation. The findings might be based on the long term effects of nicotine on the vascular system in smokers.

The Effects of 2% Dorzolamide(Trusopt) and 0.12% UF-021(Rescula)on Intraocular Pressure and Peripapillary Retinal and Optic Nerve Head Microcirculation

We investigated the effect of 2% dorzolamide and 0.12% UF-021 on intraocular pressure and peripapillary and optic nerve head microcirclation with Heidelberg Retina Flowmeter. The 40 eyes of 40 normal subjects were divided 2 groups. 2% Borzolamide and 0.12% UF-021 were instilled in each group. The IOP and microcirculation of peripillary retina and optic nerve head were measured before and 90min, 4, 8, 12, 24 hours after instillation. The IOP was decreased at 90 minutes, 4, 8 hours after instillation of 2% dorzolamide and maximal reduction of IOP was observed at 90 minutes (P0.05). We suggest that 2% dorzolamide and 0.12% UF-021 reduce the IOP, but do not alter the mictocirculation of peripapillary retina and optic nerve head.

The Acute Effect of Betaxolol and Difivefrin on Optic Nerve Head and Retinal Blood Flow in Normal Tension Glaucoma

The effect of betaxolol and dipivefrin on microcirculation of peripapil lary reina and optic disc in normal tension glaucoma was assessed. Betaxolol, selective beta-1 blocker, was known to improve the blood flow of retrobulbar arteries, and dipivefrin was known to decrease the flow of ciliary body. Total subjects were 29 normal tension glaucoma patients; 18 subjects with no previous IOP reducing eye drops during 4 weeks were assigned for betaxolol group, and 11 subjects with using timolol for dipivefrin group. The intraocular pressure was significantly reduced after instillation in betaxolol group(p<0.01), and in dipivefrin group(p<0.05). But systemic blood pressure and pulse rate were not changed after instillations in both groups. Blood flow, volume, velocity of optic disc and peripapillary retina of betaxolol group and dipivafrin group were not significantly changed. From the above results, we concluded that betaxolol and dipiverin with timolol did not influenced the microcirculation of peripapillary retina and opit disc.

The Influence of Age on Retinal and Optic Nerve Microcirculation in Normal Subjects

Perfusion disorder of the optic nerve head has been thought to be one of the risk factors glaucoma and studies on optic nerve perfusion have been performed recently. Heidelberg Retina Flowmeter(HRF: Heidelberg Engineering GbmH, heidelberg, Germany) is known to be useful in the evaluation of retinal and optic nerve head microcirculation. The objective of this study is to present the changes of retinal and optic nerve head blood flow with regard to the age in normal subjects, thus providing the reference values of retinal and optic nerve head microcirculation. Twenty subjects of each decade from third to eighth, total 120 were included in this study. Microcirculations were measured by HRF at nasal and temporal juxtapapillary retina, nasal and temporal neuroretinal rim, and optic cup area. The mean flow was measured to be 385.14 at temporal neuroretinal rim, 432.62 at nasal neuroretinal rim, and 157.12 at optic cup area. Student`s t-test revealed that there was o significant difference in flow between nasal and temporal neuroretinal rim(0.45), and between nasal and temporal juxtapapillary retina(p=0.36). Pearson`s correlation analysis revealed significant linear inverse relationship between the age and flow at neuroretinal rim(NRR) and juxtapapillary retina(JPR)(correlation coefficient r=-0.83, p=0.034 for NRR and r=-0.87, p=0.012 for JPR), but not at optic cup(r=-0.62, p=0.13).

The Acute Effects of Timolol and Betaxolol on the Peripapillary Retinal and Optic Nerve Head Microcirculation

We investigated the acute effects of timolol (beta-adrenergic non-selective) and betaxolol (beta1-adrenergic selective) on the retinal and optic nerve head (ONH) microcirculation in healthy subjects with Heidelberg Retina Flowmeter (HRF). Intraocular pressure (IOP), heart rate, blood pressure, and retinal and ONH microcirculation were measured in 7 healthy subjects (3 F/ 4 M; mean age=27.2 +/- 1.1 years) before and 90 minutes after instillation of each drug on separate occasions at 2 weeks apart. Volume, flow, and velocity of microcirculation in the peripapillary retina and neural rim of ONH were measured using HRF. Both drugs significantly reduced IOP (Wilcoxon signed rank test; p=.03) without affecting heart rate or blood pressure. It had no effect on the volume, flow, and velocity of blood flow in the peripapillary retina and ONH (Wilcoxon signed rank test; p>.1), From the above results, we concluded that both timolol and betaxolol did not alter retinal and ONH microcirculation.