Altered retrobulbar vascular reactivity in early diabetic retinopathy

AIM/BACKGROUND—In diabetic eye disease the factors leading to compromised circulation and the resulting loss of visual function are poorly understood. Although retinal circulation has been widely investigated, it accounts for only a fraction of total eye blood flow. Blood flow was investigated in the larger vessels feeding the eye in patients with early diabetic retinopathy.
METHODS—Eleven patients with early diabetes with minimal or no retinopathy and 11 healthy controls were evaluated for retrobulbar blood flow velocity using colour Doppler imaging for the ophthalmic and central retinal arteries. Patients and subjects were tested while breathing room air and again under conditions of isocapnic hyperoxia.
RESULTS—Hyperoxia induced a significant change in the central retinal artery end diastolic velocity (EDV) (p = 0.008) and resistance index (RI) (p = 0.032) in normal subjects, but not in diabetic patients. Consequently, during hyperoxia, the diabetic patients were significantly higher for EDV (p = 0.006) and significantly lower for RI (p = 0.002) compared with normal controls. Hyperoxia caused no significant change in either group in the ophthalmic artery; nevertheless, under isocapnic hyperoxia conditions the diabetic patients had lower peak systolic velocity (p = 0.05) and lower RI (p = 0.05) than normal subjects.
CONCLUSIONS—Imposition of isocapnic hyperoxia produces significant differences in the ophthalmic and central retinal artery blood flow velocities in diabetic patients with early disease when compared with normal subjects. These results demonstrate that diabetic patients with minimal or no retinopathy suffer from irregular ocular vascular function in the major vessels feeding the eye.

     

Effect of breathing 100% oxygen on retinal and optic nerve head capillary blood flow in smokers and non-smokers

AIM—The effect of breathing 100% oxygen on retinal and optic nerve head capillary blood flow in smokers and non-smokers was investigated using scanning laser Doppler flowmetry (SLDF) as a new non-invasive method to visualise and quantify ocular blood flow.
METHOD—10 eyes of 10 young healthy non-smoking volunteers (mean age 26 (SD 3) years) and nine eyes of nine young healthy smoking volunteers (mean age 26 (4) years) were investigated. All participants were asked not to smoke or consume caffeine containing drinks for at least 4 hours before the measurements. Blood flow measurements were performed before and after 100% oxygen was applied to the subjects through a mask over a period of 5 minutes (6 litres per minute). Juxtapapillary retinal and optic nerve head blood flow were determined in arbitrary units using SLDF representing a combination of laser Doppler flowmetry and a scanning laser system allowing visualisation and quantification of the retinal and optic nerve head blood flow. Blood flow was determined in an area of 100 µm × 100 µm. The level of carboxyhaemoglobin was determined in all subjects. A Wilcoxon matched pairs signed ranks test (non-parametric) was used for statistical evaluation.
RESULTS—In the non-smoking group, retinal `flow' was reduced by 33% (p = 0.005), optic nerve head `flow' by 37% (p = 0.005). In the smoking group retinal flow was reduced by 10% (p = 0.01), optic nerve head flow by 13% (p <0.008). The difference in reactivity to oxygen breathing between smokers and non-smokers was highly significant (p <0.00001). Increased carboxyhaemoglobin levels were not found in either of the groups. A significant reduction of the mean arterial blood pressure of 6% (5%) (p <0.02) was observed in the non-smoking group after administration of oxygen.
CONCLUSION—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 smokers do not respond to oxygen breathing as non-smokers do. The findings might be based on factors such as long term effects of nicotine on the sympathetic and parasympathetic nervous system.

     

Correlation Between Higher Blood Flow Velocity in the Central Retinal Vein than in the Central Retinal Artery and Severity of Nonproliferative Diabetic Retinopathy

Purpose

To assess the correlation between a higher blood flow velocity in the central retinal vein (CRV) than in the central retinal artery (CRA) and the severity of nonproliferative diabetic retinopathy (non-PDR).

Methods

We evaluated both eyes of 20 non-PDR patients with higher peak systolic velocity (PSV) in the CRV than in the CRA unilaterally as determined by color Doppler imaging (CDI). The eyes with higher PSV in the CRV were placed in group D2-H, and the fellow eyes were placed in group D2-L. The stage of non-PDR was determined by the guidelines of the Early Treatment Diabetic Retinopathy Study. Normal subjects and non-PDR patients without higher PSV in the CRV were evaluated as CDI controls.

Results

Advanced non-PDR (P = 0.001) and cystoid macular edema (P = 0.02) were statistically more frequent in group D2-H. The velocities in the ophthalmic artery and the short posterior ciliary artery were not statistically different among all groups. The velocities in the CRA were similar in all non-PDR groups and significantly lower than in the normal subjects (P < 0.05). The velocities in the CRV were significantly higher only in group D2-H (P < 0.001).

Conclusion

Higher PSV in the CRV than in the CRA was significantly correlated with the severity of non-PDR, especially in the presence of cystoid macular edema.?Jpn J Ophthalmol 2006;50:312–317 © Japanese Ophthalmological Society 2006     

Ocular vasodynamic changes in light and darkness in smokers

PURPOSE: To determine whether smokers have a reduced capacity for increased retinal blood flow velocity in darkness. METHODS: The peak systolic flow velocities (V(S)) and end diastolic flow velocities (V(D)) were measured by ultrasound (i.e., color Doppler equipment), in light and darkness in the ophthalmic and central retinal arteries in 20 cigarette smokers and 20 matched nonsmokers. The resistive index (RI) was calculated as RI = (V(S) - V(D))/V(S). RESULTS: In the ophthalmic artery in nonsmokers, the V(D) was markedly increased in darkness and the RI was correspondingly reduced. After the subject was re-exposed to light, the RI was markedly increased. In smokers the V(S) and V(D) did not change significantly in the different conditions of light and darkness. In the central retinal artery in nonsmokers, the V(S) and V(D) were markedly increased in darkness and decreased after re-exposure to light. In smokers, the corresponding changes were much smaller and not significant. CONCLUSIONS: The normal capacity for increased blood flow velocity in the central retinal artery in darkness was markedly reduced in smokers. This finding may explain the reduced dark vision after recent smoking reported in several studies and probably reflects the combined effects of an increased blood viscosity, the vasoconstrictive action of nicotine, and a reduced capacity of the blood to transport oxygen, as the hemoglobin is partly occupied by carbon monoxide.     

Acute effect of metipranolol on the retinal circulation

AIM—To assess the effect of topical and systemic application of a β adrenergic receptor blocker on retinal haemodynamics.
METHODS—24 healthy subjects were included in this double masked, randomised, placebo controlled crossover study. Metipranolol, a non-selective β adrenergic receptor blocking agent was used as test drug. In all subjects arm-retina time, arteriovenous passage time, arterial mean dye velocity, the arterial vessel diameters, and capillary flow velocity were quantified from digital video fluorescein angiograms.
RESULTS—A significant effect was observed on the arteriovenous passage time (p<0.05), the arterial mean dye bolus velocity (p<0.05), and capillary blood velocity (p<0.05), but not on the arterial vessel diameter. The arterial mean dye bolus velocity and capillary blood velocity increased after application of the test drug (topical and systemic). In tandem with this a decrease of the arteriovenous passage time was observed. The perfusion pressure increased after topical application and remained unchanged after systemic application of metipranolol.
CONCLUSIONS—This study shows that systemic as well as topical application of metipranolol leads to increased retinal blood flow velocities. The implications of these results for treatment with β adrenergic receptor blockers is not clear. However, in view of these data it is very unlikely that treatment with metipranolol has a negative effect on retinal blood flow.

Keywords: retinal microcirculation; β adrenergic blockers; scanning laser ophthalmoscopy     

Orbital blood flow parameters in unilateral pseudoexfoliation syndrome

Purpose The evaluation of orbital blood flow parameters in patients with unilateral pseudoexfoliation syndrome (XFS) and in age–sex-matched control subjects using color Doppler imaging. Methods This prospective, comparative case series included 33 unilateral XFS patients and 33 age–sex-matched control subjects. Color Doppler imaging was used to evaluate the XFS-affected (Group 1) and -unaffected (Group 2) eyes that were matched with the corresponding side (Groups 3 and 4) of control subjects. All subjects were given a complete ophthalmological examination. A masked radiologist obtained the peak systolic velocity (PSV) and end diastolic velocity (EDV) of ophthalmic (OA), central retinal (CRA), nasal posterior ciliary (NPCA) and temporal posterior ciliary arteries (TPCA) as well as mean velocity of central retinal vein (CRV). Resistivity indices (RI) were calculated. Results Analysis of peak systolic and end diastolic velocity (PSV, EDV) and RI between Groups 1–2 and 3–4 did not show any significant difference. Comparing Groups 1–3 (corresponding eyes of pseudoexfoliation-affected and control subjects) and Groups 2–4 (corresponding eyes of pseudoexfoliation-unaffected and control subjects) revealed significantly low values for OA, PSV and EDV in both eyes of the XFS patients. The OA RI value in Group 1 was found to be significantly higher than that in Group 3 with the cut-off value of 0.72. Conclusion These findings suggest that ophthalmic artery hemodynamic parameters change in both eyes of unilateral XFS patients, illustrating out the systemic nature of the disease. We conclude that XFS decreases OA blood flow velocities and increases vascular resistance through progressive build-up.     

Effects of 0.5% apraclonidine on optic nerve head and peripapillary retinal blood flow

AIMS—To examine the effects of 0.5% apraclonidine on optic nerve head (ONH) and peripapillary retinal blood flow by scanning laser Doppler flowmetry (SLDF).
METHODS—ONH and peripapillary retinal blood flow of 17 healthy subjects were measured by SLDF before and 1 hour and 3 hours after unilateral administration of 0.5% apraclonidine. The fellow eyes were treated with balanced salt solution and the examiners were masked as to which eye was treated with apraclonidine. On each occasion, three scans were obtained and haemodynamic variables (volume, flow, and velocity) were analysed at eight locations, four in the neural rim and four in the peripapillary retina, avoiding ophthalmoscopically visible vessels. The statistical significance of changes from the baseline value of variables and the differences in the measured quantities between apraclonidine treated eyes and fellow eyes at each time point were evaluated using Wilcoxon signed rank test.
RESULTS—The intraocular pressure was reduced significantly in apraclonidine treated eyes by 15.0% (p=0.001) at 1 hour and 30.0% (p=0.000) at 3 hours after administration. In the volume, flow, or velocity of ONH and peripapillary retinal blood flow, there were no significant changes from the baseline values at 1 hour and 3 hours after apraclonidine administration in either apraclonidine treated eyes (p >0.4) or fellow eyes (p >0.2). Also, no significant differences were found in the measured quantities between apraclonidine treated eyes and fellow eyes at each time point (p >0.1).
CONCLUSION—A single dose of topical apraclonidine 0.5% in healthy subjects does not have adverse effects on the ONH and peripapillary retinal blood flow.

     

Value of color doppler imaging in the diagnosis of occlusive retinal venous lesions

A hundred and twenty-five patients aged 47 to 72 years who had retinal venous occlusions were examined. Occlusion of the central retinal vein (CRV) was observed in 82 (65.6%) patients and that of CRV branches was seen in 43 (34.4%) patients. In all the patients, color Doppler imaging (CDI) was performed to study blood flow in the ophthalmic artery, central retinal artery (CRA), CRV, and short posterior ciliary arteries. The study indicated a marked reduction in diastolic velocity, no diastolic component of the Doppler blood flow spectrum, and a significant increase in the CRA resistance index (from 0.9 to 1.0), and a pronounced decrease in the maximum systolic velocity in the CRV, as well as a considerable reduction in blood flow velocity parameters, and a rise in the resistance index in the ophthalmic artery and short posterior ciliary arteries. CDI is a highly informative, non-invasive technique that makes it possible to study the blood flow in the CRA and CRV for the evaluation the severity of disease and the efficiency of therapy for occlusive retinal venous lesions.     

Hemodynamic evaluation of the posterior ciliary circulation in exfoliation syndrome and exfoliation glaucoma

BACKGROUND: Previous studies have reported impaired blood flow in the ophthalmic artery (OA) and central retinal artery (CRA) in exfoliation syndrome and exfoliation glaucoma. This study evaluates blood flow at the long and short posterior ciliary arteries (LPCA and SPCA, respectively) in these conditions. METHODS: Consecutively examined candidates for cataract surgery were included. Only one eye (OD) was included in the analyses for consistency. Patients were classified into non-glaucoma and non-exfoliation (controls), primary open angle glaucoma (POAG), exfoliation syndrome and exfoliation glaucoma groups, based on the findings of the OD. Sixty-eight patients (41 males, 60.3%) were included. Color Doppler imaging (CDI) of the nasal and temporal branches of LPCA and SPCA was performed using a 7.5 Mhz probe. The peak systolic velocity (PSV), end diastolic velocity (EDV) and resistivity index (RI) were recorded for the examined vessels. RESULTS: EDV at the LPCA was significantly lower in exfoliation syndrome and glaucoma, compared with controls and POAG respectively. EDV was significantly lower and RI was significantly higher at the SPCA in exfoliation glaucoma, compared with exfoliation, whereas respective differences were statistically not significant between controls and POAG. CONCLUSIONS: The hemodynamic impairment at the LPCA in exfoliation syndrome and glaucoma supports an association between exfoliation and ischemic stress at the anterior ocular segment.     

Retrobulbar circulation in myopic patients with or without myopic choroidal neovascularisation

AIM: To investigate the effect of myopia and myopic choroidal neovascularisation (CNV) on retrobulbar circulation in central retinal artery (CRA) and vein (CRV) and posterior ciliary artery (PCA). METHODS: 52 subjects with and without myopia were included in the study. Retrobulbar circulation was measured using colour Doppler imaging. Analysis of correlation of degree of myopia with blood flow velocity parameters was done. Circulatory differences between eyes of patients with unilateral neovascular degenerative myopia were estimated. RESULTS: The analysis of correlation between dioptry and blood flow velocity in the CRA, CRV, and PCA showed a significant positive correlation. Axial length was also significantly correlated with CRA and CRV blood velocity and had a tendency to be correlated with PCA blood velocity. When compared with the fellow eye, the eye with myopic CNV had significantly higher resistivity index (RI) (p=0.048) in the PCA and no significant difference in the circulatory parameters of the CRA and CRV. CONCLUSION: Central retinal and posterior ciliary blood velocity decreases with the increase of the degree of myopia. PCA RI is higher in myopic CNV.     

Orbital color Doppler imaging in Behçet’s disease with or without ocular involvement

Purpose

To investigate the value of color Doppler imaging (CDI) of orbital vasculature in the assessment of ocular involvement in patients with Behçet’s disease (BD) without clinical ophthalmologic abnormalities.

Methods

CDI of the orbital vessels were performed on 26 eyes of 13 patients who were diagnosed as having BD with ocular involvement (group 1), 65 eyes of 33 patients who had BD without ocular involvement (group 2) and 40 eyes of 20 healthy volunteers (group 3). Peak systolic (PSV) and end-diastolic (EDV) blood flow velocities and resistivity index (RI) measurements were obtained for the ophthalmic artery (OA) and central retinal artery (CRA). The mean velocity of the central retinal vein (CRV) was also measured.

Results

For the OA, PSV and EDVs were significantly lower and RIs were significantly higher in group 2 than in control subjects. In group 1, only the EDVs of OA were significantly lower than in healthy subjects. For the CRA, PSV and EDVs were significantly lower, and RIs were significantly higher in both BD groups than those in group 3. When group 1 and group 2 were compared, the differences between PSV, EDV and RI measurements for the CRA and OA were statistically insignificant. There was no significant difference in blood flow velocity of the CRV between the three groups.

Conclusion

Major hemodynamic changes were observed in the ophthalmic vasculature of Behçet’s patients with or without ocular involvement by CDI. CDI may detect ocular blood flow alterations before initial clinical manifestations.

     

The Effect of Tilted Disc Syndrome on Ocular Hemodynamic Measurements

Background: The purpose of this study was to assess ocular hemodynamics in patients with unilateral tilted disc syndrome (TDS) using color Doppler ultrasonography (CDUS). Methods: Fifteen consecutive patients with unilateral TDS and normal-appearing contralateral optic nerves were enrolled. Both eyes of all participants underwent detailed ophthalmological examination including automated visual field testing. CDUS was performed in the eyes with tilted discs and fellow unaffected eyes. Peak systolic velocities, end diastolic velocities, and vessel resistance were measured in the ophthalmic artery (OA), central retinal artery (CRA), nasal posterior ciliary artery (NPCA), and temporal posterior ciliary artery (TPCA). The minimum and maximum blood flow velocities were also measured in the central retinal vein (CRV). Results: No statistically significant differences were found between eyes with tilted discs and fellow normal eyes in terms of OA, CRA, NPCA, or TPCA mean peak systolic or end diastolic velocities, resistivity indices, and the mean maximal and minimal CRV blood flow velocities. Conclusion: Ocular hemodynamic measurements determined by CDUS do not appear to be altered in tilted disc syndrome.     

Color Doppler Imaging of the Orbital Vessels in Ankylosing Spondylitis

Abstract

Purpose: To analyze the hemodynamic features of orbital blood flow velocities using Doppler ultrasonography in ankylosing spondiylitis (AS) patients, as well as to compare these results with those of healthy controls. Methods: 33 AS patients and 32 healthy controls were consecutively included in the study groups. The same radiologist performed ocular blood flow measurements. Peak systolic velocity (PSV), end diastolic velocity (EDV), and resistive index (RI) were measured in the central retinal artery (CRA), posterior ciliary arteries (PCAs), and ophthalmic artery (OA). Resistive index was used to assess arterial resistance; it was automatically calculated as RI [(PSV–EDV)/PSV]. Results: There were no significant differences in the PSV, EDV, and RI of the OA, CRA, and PCAs between AS patients and controls. Conclusion: This result suggests no possible contributory role of vascular structures in formation of uveitis in AS. We believe that our preliminary results need to be complemented with further studies, particularly including AS patients with uveitis and rheumatic diseases with other ocular involvement.     

视网膜静脉阻塞眼底血流超声初步研究

目的：观察视网膜静脉阻塞患者视网膜中央血管系统的微循环变化。方法：运用超声多普勒技术对视网膜静脉阻塞患者47眼作视网膜中央动脉（CRA）和视网膜中央静脉（CRV）血流速度的检测。结果：患者CRA,CRV的血流速度下降明显（P＜0.01）,与眼别、年龄、性别无明显差别;舒张末期血流速度（EDV）、收缩期血流加速度（A）反应灵敏,早期 即有变化（P＜0.01）;收缩期峰值血流速度（PSV）下降则相对滞后;阻力指数（RI）变化不大。部分静脉郁滞性视网膜病变（VSR）患者的各测值以后均回升,而出血性网膜病变（HR）者却不变。早期综合治疗对部分VSR患者的预后有利。结论：血流速度超声检测指数敏感地反映了视网膜微循环情况,可作为病情、预后及疗效观察的参考依据。     

Ocular blood flow velocities in patients with proliferative diabetic retinopathy and healthy volunteers: a prospective study.

BACKGROUND--Diabetes affects the vascular ocular circulation. Colour Doppler imaging allows for simultaneous two dimensional anatomical imaging and Doppler evaluation of blood flow velocity; with this technique ocular blood flow velocity can be evaluated in normal and diabetic patients. METHODS--A prospective study compared blood flow velocity in ocular vessels (ophthalmic artery, posterior ciliary arteries, central retinal vessels, and vortex veins) of 25 patients with proliferative diabetic retinopathy and 30 age matched normal subjects using a colour Doppler imaging unit (Toshiba Sonolayer SSA-270 A with a 5.0 MHz PLF-503 ST phased array scanning head). RESULTS--The diabetic patients had lower blood velocities than the volunteers. There were significant differences in ophthalmic artery; systolic (p < 0.01), diastolic (p < 0.001), mean velocity (p < 0.05), and central retinal artery; systolic (p < 0.001), diastolic (p < 0.001), mean velocity (p < 0.05). No significant correlations were found between age and blood velocities. CONCLUSION--Ocular blood flow velocity was decreased in diabetic patients with proliferative diabetic retinopathy.     

玻璃体切割联合眼内全视网膜光凝对PDR合并虹膜新生血管的视网膜供血影响

目的：探讨玻璃体切割联合眼内全视网膜光凝对增殖性糖尿病视网膜病变( proliferative diabetic retinopathy,PDR)合并虹膜新生血管( iris neovascularization,NVI)患者视网膜供血的影响及其临床价值。
　　方法：采用彩色多普勒超声血流显像技术( color doppler flow imaging,CDFI)检测21例21眼PDR合并NVI患者行玻璃体切割联合眼内光凝术前、术后3 mo视网膜中央动脉( central retinal artery, CRA )、睫状后短动脉( shot posterior ciliary artery, sPCA )、眼动脉( ophthalmic artery, OA)的收缩期峰值流速( peak systolic velocity,PSV)、舒张末期血流速度( end diastolic velocity, EDV )、阻力指数( resistance index,RI)的变化。
　　结果：玻璃体切割联合眼内全视网膜光凝术后3 mo CRA的PSV、EDV较术前明显升高,而RI值下降,有统计学差异( P<0.05)。 sPCA及OA各项血流参数手术前后改变无统计学差异(P>0.05)。
　　结论：玻璃体切割联合眼内光凝可以提高PDR合并NVI患者术后CRA的血流速度,降低远端视网膜血管的RI,改善眼视网膜的血液供应,延缓或阻止患者向新生血管性青光眼( NVG)的发展与发生。     

Retrobulbar and common carotid artery haemodynamics and carotid wall thickness in patients with non-arteritic anterior ischaemic optic neuropathy

Purpose

To evaluate retrobulbar and common carotid artery (CCA) haemodynamics and CCA wall thickness in the patients with acute unilateral non-arteritic anterior ischaemic optic neuropathy (NAION) by colour Doppler imaging (CDI).

Methods

Twenty-two patients with acute unilateral NAION and 28 age- and sex-matched controls were included in this prospective study. By CDI, the peak-systolic velocity (PSV) and end-diastolic velocity (EDV) of the ophthalmic artery (OA) and central retinal artery (CRA) in both eyes were measured or calculated. Intima-media thickness (IMT) and blood flow velocity were measured in both CCAs. Measurements on the affected side of the patients were compared to the contralateral healthy side and the controls.

Results

Compared to the controls, the blood flow velocities in the CRA were significantly decreased (p?<?0.05), and IMT of CCA was greater (p?<?0.001) on the affected side, while the blood flow velocities in the OA and CCA showed no statistically significant difference. The blood flow velocities in the CRA tended to be reduced bilaterally in the patients with NAION, and the difference of PSV and EDV was insignificant between the affected eyes and fellow eyes (p?=?0.69, 0.86 respectively). No marked differences between the controls and the unaffected sides were detected, neither for the blood flow velocities in CRA, OA, CCA nor for the IMT of CCA.

Conclusion

Decreased blood velocities of CRA and increased carotid wall thickness were found on the affected side of acute NAION compared to healthy controls. These findings might be potentially useful in the treatment monitoring of NAION.     

Human ocular vasodynamic changes in light and darkness.

PURPOSE: To determine whether changes in the retinal blood flow in light and darkness occur in humans. METHODS; The systolic and diastolic flow velocities were measured by color Doppler in the ophthalmic and the central retinal arteries in 12 healthy individuals in light and darkness. RESULTS: In the ophthalmic artery there was a trend toward lower systolic velocity in darkness compared with that in the light, but there was no change in diastolic velocity. In the central retinal artery the systolic and the diastolic flow velocities were markedly increased in darkness. After re-exposure to light the systolic flow velocity decreased. CONCLUSIONS: Darkness is associated with increased blood flow velocity in the central retinal artery, probably reflecting increased retinal metabolic demands by the photoreceptors.     

Smoking and neovascular form of age related macular degeneration in late middle aged males: findings from a case-control study in Japan

AIMS—The risk of smoking habits for developing the neovascular form of age related macular degeneration (neovascular form of AMD) were studied by a case-control study in Japan.
METHODS—56 male patients with the neovascular form of AMD and 82 healthy male controls, aged 50 to 69 years, were enrolled. A self administered questionnaire provided necessary information for the study subjects. Questions on smoking included whether the study subjects have ever smoked or not, and if smoked, depth of smoke inhalation, use of extra filter, age at starting smoking, average number of cigarettes smoked per day, and duration of smoking. When a smoker had stopped smoking, age at cessation was also recorded. Unconditional logistic analysis was adapted to calculate age adjusted odds ratios and their 95% confidence intervals (CIs) for smoking related factors.
RESULTS—Age adjusted odds ratio of developing the neovascular form of AMD was 2.97 (95% CI 1.00-8.84) for current smokers and 2.09 (0.71-6.13) for ex smokers, compared with non-smokers. All smoking habit/smoking history related variables such as use of extra filter, smoke inhalation level, age at starting smoking, duration of smoking, and Brinkman index were found to be significantly related to an increased risk of the neovascular form of AMD.
CONCLUSIONS—Suggested is the strong possibility that cigarette smoking enhances the neovascular form of AMD risk in late middle aged males, though the magnitude of risk by smoking variables might be overestimated, in part, because of health oriented controls.

     

激光治疗糖尿病视网膜病变后眼血流动力学的改变

目的 探讨激光治疗对糖尿病视网膜病变（DR）患眼血流动力学的影响。方法采用Zeiss Visulas 532s眼科激光治疗仪对35例（56眼）DR行泛视网膜光凝治疗,用彩色多普勒超声检测激光治疗前后DR患眼眼动脉（OA）和视网膜中央动脉（CRA）的血流状态。并与30例（60眼）正常人的OA和CRA血流进行对照。结果DR组与对照组相比,OA和CRA的收缩期血流峰速,舒张末期流速及平均流速均降低,阻力指数增高;激光治疗后DR患眼OA和CRA收缩期血流峰速,舒张末期流速,平均流速均降低,阻力指数增高。结论糖尿病视网膜病变患者OA和CRA的血流速度降低,视网膜循环阻力升高,视网膜血液供应不良。激光治疗导致DR患眼视网膜血流降低。