Anat Lowenstein

Reduced retinal blood flow velocity in diabetic retinopathy.

Purpose: The purpose of this study was to compare the retinal blood flow velocities of patients with diabetes and healthy control subjects. We used a novel device offering a noninvasive diagnostic of retinal function. Methods: Flow velocities in retinal arterioles and venules were quantitatively analyzed by retinal function imager scanning in 58 eyes of 42 patients with nonproliferative diabetic retinopathy and 51 eyes of 32 normal subjects. Group differences were assessed by the mixed-model effect. Results: Average velocity in arterial compartments (in mm/s) was 3.74 ± 1.09 for the diabetic group and 4.19 ± 0.99 for the control subjects. The average velocity of all segments, taking associated heart rate and individual segment widths into account, was 17% slower in the diabetic group (P < 0.0001). In both groups, average venous compartment velocity was lower than the arterial velocity (2.61 ± 0.65 for the diabetic group; 3.03 ± 0.59 for the control subjects). Individual vein velocities, taking heart rate and segment widths into account, was 17% slower, on average, in the diabetic group (P < 0.0001). Conclusion: Our measurement showed significantly decreased flow velocities in the retinal arterioles and venules of patients with diabetes compared with healthy control subjects, supporting the view of abnormal vessel function in eyes with nonproliferative diabetic retinopathy.

Increased retinal blood flow velocity in patients with early diabetes mellitus.

Purpose: To compare retinal blood flow velocity in small vessels of patients with early diabetes mellitus (DM), without any morphologic changes related to diabetic retinopathy, with that in a control group. Methods: The authors used the retinal function imager to measure blood flow velocities, from many small vessels, simultaneously. Twenty-three eyes of 14 patients with early DM and 51 eyes of 31 healthy subjects were enrolled. Differences between the patients and the control group were assessed by mixed linear models. Results: Venous average velocity significantly increased in the DM group (3.8 ± 1.2 vs. 2.9 ± 0.5 mm/second, P < 0.0001) than in the healthy subjects. Arterial velocity of DM patients was also significantly higher (4.7 ± 1.7 vs. 4.1 ± 0.9 mm/second, P = 0.03). There was no statistically significant difference between groups in age, gender, heart rate, and systolic blood pressure. The diastolic blood pressure in the DM patients was lower than that in the healthy group (P = 0.03). Conclusion: There was an increase in arterial and venous retinal blood flow velocities of patients with early DM with no diabetic retinopathy. These findings support the notion that abnormalities in vessel function exist in diabetic eyes before the development of structural changes. This noninvasive approach facilitated the assessment of early hemodynamic abnormalities and may assist in screening and monitoring.

The correlation between retinal blood flow velocity measured by the retinal function imager and various physiological parameters.

BACKGROUND AND OBJECTIVE The retinal function imager (RFI) (Optical Imaging Ltd., Rehovot, Israel) measures retinal blood flow velocity non-invasively. The authors studied the reproducibility of these measurements and assessed the effect of physiological components on them. PATIENTS AND METHODS Sixty-seven individuals with no retinal pathology were recruited. Velocity reproducibility was verified by comparing repeated RFI measurements. The correlation of the velocity with physiological parameters was assessed by mixed linear and Gaussian models. RESULTS The average velocity was 4.2 ± 0.9 mm/sec arterial and 3.3 ± 0.8 mm/sec venous. Variability was 7.5% ± 3.7% and interclass correlation coefficient was r = 0.744. Venous velocity decreased after 40 years of age (0.32 mm/sec per decade, P < .01). Arterial velocity increased as mean arterial pressure increased (0.25 mm/sec per 10 mm Hg, P < .01). There was also a positive association between velocities and heart rate (arteries: 0.21 mm/sec per 10 bpm, P < .05; veins: 0.22 mm/sec per 10 bpm, P < .01). CONCLUSION The RFI provides a reproducible, non-invasive technique to assess retinal velocities.

Ophthalmologists, suicide bombings and getting it right in the emergency department

BackgroundThe number and extent of worldwide suicide attacks has risen sharply in recent years. The objectives of this retrospective study are: to determine the prevalence and outcome of the victims who sustained ocular injury, to describe the activities of ophthalmologists in the setting of an emergency department (ED) receiving mass casualties of a suicide bombing attack and to illustrate some of the treatment obstacles that they encountered and the protocol.MethodsA single-centre, retrospective, interventional case series.ParticipantsParticipants were the victims of 13 suicide bombing attacks (2000–2004), treated at a level I trauma center of an Israeli tertiary care, municipal medical center.Main outcome measuresThe study includes a description of the ophthalmologist’s role in the setting of mass evacuation to emergency facilities, prevalence and outcome of patients managed according to the recommended guidelines, and reemphasis of logistic and therapeutic guidelines for management of ocular injuries.ResultsThe trauma center database yielded information on a total of 352 casualties from 13 suicide bombing attacks, including 17 surviving patients with any ocular/periocular trauma resulting from suicide bombing attacks. Six eyes required and underwent urgent primary closure of laceration for primary repair of open globe, one unsalvageable eye underwent primary enucleation, and two eyes underwent exploration of subconjunctival hemorrhage. Four eyes required additional surgical intervention, which was performed within 7 days (large intravitreal foreign bodies were extracted from three eyes whose final visual acuity was poor, and an intra-lenticular foreign body was extracted from the fourth eye whose final visual acuity was 6/12). The remaining eight patients received medical treatment as indicated and were continued to be followed up.DiscussionOcular trauma management under conditions of mass injuries requires special utilization of manpower and resources. Guidelines for efficacious patient management, description of the ophthalmologist’s role, and the experience of one emergency facility are presented.

Influence of Non-Toxic Doses of Bevacizumab and Ranibizumab on Endothelial Functions and Inhibition of Angiogenesis

Purpose: Ranibizumab (Lucentis) is an antibody fragment developed against all fragments of vascular endothelial growth factor (VEGF) that was approved by the FDA for treating age-related macular degeneration (AMD). Bevacizumab, a full-length anti-VEGF antibody approved for use in colon cancer, is non-FDA approved at this time but it is widely used for treating AMD. The purpose of this study was to compare the influence of Bevacizumab and Ranibizumab on angiogenesis in an in vitro model. Methods: A model consisting of H5V cells derived from murine hearts capillary endothelial cells (ECs) was used. The H5V cells were treated with three concentrations of Bevacizumab and Ranibizumab (0.125 mg/mL, 0.25 mg/mL, and 0.50 mg/mL) for 24 hr before all experiments. The effects of Bevacizumab and Ranibizumab on EC proliferation were compared by 3H-thymidine incorporation essay. Toxic effects and the safety of each drug in clinical concentrations were assessed by annexin 5 staining. The effects of the drugs on ECs functions were assessed by their ability to adhere to fibronectin and by evaluation of the cells’ tube formation capacity on matrigel. Results: Both Bevacizumab and Ranibizumab equally suppressed the adhesive properties of ECs to fibronectin, and similarly inhibited ECs’ proliferation capacity in a dose-dependent manner. Both Bevacizumab and Ranibizumab inhibited the ECs’ tube formation capacity on matrigel, and were equally safe. Conclusions: Ranibizumab and Bevacizumab at low, non-toxic doses similarly inhibit several properties of the angiogenesis process. Inhibition of ECs adhesion to fibronectin and tube formation capacity does not seem to be directly related to the anti-angiogenic effects as indicated by inhibition of VEGF. Further studies for delineating the exact mechanism of action of Ranibizumab and Bevacizumab in angiogenesis are warranted.