Showing papers by "Philip J. Rosenfeld published in 2008"

Predicted Biological Activity of Intravitreal VEGF TRAP

Abstract: Aim: To compare the intravitreal binding activity of VEGF Trap with that of ranibizumab against vascular endothelial growth factor (VEGF) using a time-dependent and dose-dependent mathematical model. Methods: Intravitreal half-lives and relative equimolar VEGF-binding activities of VEGF Trap and ranibizumab were incorporated into a first-order decay model. Time-dependent VEGF Trap activities (relative to ranibizumab) for different initial doses (0.5, 1.15, 2 and 4 mg) were calculated and plotted. Results: Seventy-nine days after a single VEGF Trap (1.15 mg) injection, the intravitreal VEGF-binding activity would be comparable to ranibizumab at 30 days. After injection of 0.5, 2 and 4 mg VEGF Trap, the intravitreal VEGF-binding activities (comparable to ranibizumab at 30 days) would occur at 73, 83 and 87 days, respectively Conclusion: On the basis of this mathematical model, VEGF Trap maintains significant intravitreal VEGF-binding activity for 10–12 weeks after a single injection.

Long-term safety and efficacy of intravitreal bevacizumab (avastin) for the management of central retinal vein occlusion

Abstract: PURPOSE To evaluate the long-term safety and efficacy of intravitreal bevacizumab injections (Avastin, Genentech Inc., San Francisco, CA) for the treatment of macular edema secondary to central retinal vein occlusions. METHODS A retrospective review was performed of eyes treated from May 2005 to August 2006 with follow-up through February 2007. The dose of bevacizumab was 1.25 mg (0.05 mL). Retreatment was performed at monthly or longer intervals at the discretion of the treating physician. RESULTS Fifty-seven eyes received intravitreal bevacizumab at baseline. Visual acuity improved by a mean of 14 letters (N = 53; P < 0.001) at 1 month, 13 letters at 3 months (N = 53; P < 0.001), 9 letters at 6 months (N = 30; P = 0.001), 9 letters at 12 months (N = 17; P = 0.004). The mean optical coherence tomography thickness decreased by 299 microm at 1 month (N = 53; P < 0.001), 144 microm at 3 months, (N = 53; P < 0.001), 127 microm at 6 months (N = 30; P = 0.011), and 276 microm at 12 months (N = 17; P < 0.001). No ocular or systemic adverse events were observed. CONCLUSION Improvements in visual acuity and optical coherence tomography were observed during the first year following intravitreal bevacizumab for macular edema secondary to central retinal vein occlusions. These retrospective results provide additional evidence to support the perceived safety and efficacy of intravitreal bevacizumab in this disorder.

Imaging serpiginous choroidopathy with spectral domain optical coherence tomography.

Abstract: The use of spectral domain optical coherence tomography (SD-OCT) in the study of chronic serpiginous choroiditis was evaluated. Two patients with chronic serpiginous choroiditis were imaged using two prototype SD-OCT systems (6-microm axial resolution). Raster scans covering 6 x 6 X 2-mm regions of the retina were obtained, enabling the study of different retinal cross-sectional images. Thickness maps were obtained after segmentation of retinal layers, which could be compared with those on follow-up. SD-OCT allowed the visualization of the cross-sectional retinal architecture at different horizontal positions. Superimposition of SD-OCT generated reconstructed fundus images with fundus photographs provided accurate images registration. Segmentation of retinal layers provided thickness maps and higher-density improved visualization of photoreceptor layer, cysts, and atrophy, which was useful in following change in disease activity over time. The researchers concluded that SD-OCT is a useful tool to study disease morphology and follow-up of chronic serpiginous choroiditis.

Calibration of fundus images using spectral domain optical coherence tomography.

Abstract: Background and objective Measurements performed on fundus images using current software are not accurate. Accurate measurements can be obtained only by calibrating a fundus camera using measurements between fixed retinal landmarks, such as the dimensions of the optic nerve, or by relying on a calibrated model eye provided by a reading center. However, calibrated spectral domain OCT (SD-OCT) could offer a convenient alternative method for the calibration of any fundus image. Patients and methods The ability to measure exact distances on SD-OCT fundus images was tested by measuring the distance between the center of the fovea and the optic nerve. Calibrated SD-OCT scans measuring 6 X 6 X 2 mm centered on the fovea and the optic nerve were analyzed in 50 healthy right eyes. The foveal center was identified using cross-sectional SD-OCT images, and the center of the optic nerve was identified manually. The SD-OCT scans were registered to each other, and the distances between the center of the optic nerve and fovea were calculated. The overlay of these SD-OCT fundus images on photographic fundus images was performed. Results Any image of the fundus could be calibrated by overlaying the SD-OCT fundus image, and the measurements were consistent with previously defined calibration methods. The mean distance between the center of the fovea and the center of the optic nerve was 4.32 +/-0.32 mm. The line from the center of the optic nerve to the foveal center had a mean declination of 7.67 +/- 3.88 degrees. Mean horizontal displacement and vertical displacement were 4.27 +/- 0.29 mm and 0.58 +/- 0.29 mm, respectively. Conclusions The overlay of the SD-OCT fundus image provides a convenient method for calibrating any image of the fundus. This approach should provide a uniform standard when comparing images from different devices and from different reading centers.

Geometric Deformable Model Driven by CoCRFs: Application to Optical Coherence Tomography

Abstract: We present a geometric deformable model driven by dynamically updated probability fields. The shape is defined with the signed distance function, and the internal (smoothness) energy consists of a C1continuity constraint, a shape prior, and a term that forces the zero-level of the shape distance function towards a connected form. The image probability fields are estimated by our collaborative Conditional Random Field (CoCRF), which is updated during the evolution in an active learning manner: it infers class posteriors in pixels or regions with feature ambiguities by assessing the joint appearance of neighboring sites and using the classification confidence. We apply our method to Optical Coherence Tomography fundus images for the segmentation of geographic atrophies in dry age-related macular degeneration of the human eye.

Comparison of 2.5 mg/kg and 5 mg/kg systemic bevacizumab in neovascular age-related macular degeneration: twenty-four week results of an uncontrolled, prospective cohort study.

Abstract: Background: To compare safety, visual acuity (VA), and anatomic outcomes of 2.5 mg/kg and 5 mg/kg intravenous bevacizumab in patients with neovascular age-related macular degeneration. Methods: In an institutional cohort study, 16 patients (2 cohorts, 27 eyes) with neovascular age-related macular degeneration were treated with 5 mg/kg intravenous bevacizumab and 2.5 mg/kg, respectively. All patients received 3 initial intravenous infusions at 2-week intervals. The main outcome measures were VA, optical coherence tomography, and fluorescein angiography. Results: No serious systemic or ocular adverse events were identified. By Day 7, mean VA increased from 56 letters (20/80+1) at baseline to 60 letters (20/63) in the 5 mg/kg group and mean central retinal thickness decreased by 83 [mu]m. In the 2.5 mg/kg group, mean VA increased from 55 letters (20/80) to 66 letters (20/50+1) and mean central retinal thickness decreased by 93 [mu]m. By Month 3, VA improved by 10 letters compared to baseline in the 5 mg/kg group and by 9 letters in the 2.5 mg/kg group. Central retinal thickness was reduced by 128 [mu]m in the 5 mg/kg group and by 127 [mu]m in the 2.5 mg/kg group. These benefits were sustained through 6 months. No statistically significant difference was found between both treatment groups regarding safety, VA, and anatomic outcomes. Conclusion: Similar VA, optical coherence tomography, and angiographic improvements were observed in both treatment groups up to 6 months. Further follow-up is required to evaluate the long-term durability and safety of both treatment regimens.

Ultra High-Resolution Optical Coherence Tomography for Non-contact Ocular Imaging of Small Animals

Abstract: An ultra-high resolution spectral domain OCT system was built for non-contact imaging of retina and anterior segment of small animals. Short imaging time and high imaging quality make the system promising for high throughput applications.

Imaging Serpiginous Choroidopathy With Spectral-Domain Optical Coherence Tomography

Abstract: The use of spectral domain optical coherence tomography (SD-OCT) in the study of chronic serpiginous choroiditis was evaluated. Two patients with chronic serpiginous choroiditis were imaged using two prototype SD-OCT systems (6-µm axial resolution). Raster scans covering 6 × 6 × 2-mm regions of the retina were obtained, enabling the study of different retinal cross-sectional images. Thickness maps were obtained after segmentation of retinal layers, which could be compared with those on follow-up. SD-OCT allowed the visualization of the cross-sectional retinal architecture at different horizontal positions. Superimposition of SD-OCT generated reconstructed fundus images with fundus photographs provided accurate images registration. Segmentation of retinal layers provided thickness maps and higher-density improved visualization of photoreceptor layer, cysts, and atrophy, which was useful in following change in disease activity over time. The researchers concluded that SD-OCT is a useful tool to study disease morphology and follow-up of chronic serpiginous choroiditis. [Ophthalmic Surg Lasers Imaging 2008;39:S95-S98.]