Comparison of indocyanine green and fluorescein angiography of choroidal neovascularization

FITC-Labeled RGD Peptides as Novel Contrast Agents for Functional Fluorescent Angiographic Detection of Retinal and Choroidal Neovascularization

The development of choroidal neovascularization (CNV) is a crucial factor in the pathophysiology and prognosis of exudative age-related macular degeneration (AMD). Therefore, the detection of CNV is essential for establishing an appropriate diagnosis and treatment plan. Current ophthalmic imaging techniques, such as fundus fluorescent angiography and optical coherence tomography, have limitations in accurately visualizing CNV lesions and expressing CNV activity, owing to issues such as excessive dye leakage with pooling and the inability to provide functional information. Here, using the arginine-glycine-aspartic acid (RGD) peptide's affinity for integrin α_vβ₃, which is expressed in the neovascular endothelial cells in ocular tissues, we propose the use of fluorescein isothiocyanate (FITC)-labeled RGD peptide as a novel dye for effective molecular imaging of CNV. FITC-labeled RGD peptides (FITC-RGD₂), prepared by bioconjugation of one FITC molecule with two RGD peptides, demonstrated better visualization and precise localization of CNV lesions than conventional fluorescein dyes in laser-induced CNV rodent models, as assessed using various imaging techniques, including a commercially available clinical fundus camera (Optos). These results suggest that FITC-RGD₂ can serve as an effective novel dye for the diagnosis of neovascular retinal diseases, including AMD, by enabling early detection and treatment of disease occurrence and recurrence after treatment.

Tetrahedral framework nucleic acids-based delivery of microRNA-155 inhibits choroidal neovascularization by regulating the polarization of macrophages

Choroidal neovascularization (CNV) is a common pathological feature of various eye diseases and an important cause of visual impairment in middle-aged and elderly patients. In previous studies, tetrahedral framework nucleic acids (tFNAs) showed good carrier performance. In this experiment, we developed microRNA-155-equipped tFNAs (T-155) and explored its biological effects on CNV. Based on the results of in-vitro experiments, T-155 could regulate macrophages into the antiangiogenic M1 type. Then, we injected T-155 into the vitreous of laser-induced CNV model mice and found that T-155 significantly reduced the size and area of CNV, inhibited blood vessel leakage. In summary, we prove that T-155 could regulate the inflammatory process of CNV by polarizing macrophages, thereby improving the symptoms of CNV. Thus, T-155 might become a new DNA-based drug with great potential for treating CNV.

•

T-155 could regulate the inflammatory process of CNV by polarizing macrophages, thereby improving the symptoms of CNV.

•

Thus, T-155 might become a new DNA-based drug with great potential for treating CNV.

In Vivo Efficacy of an Injectable Microsphere-Hydrogel Ocular Drug Delivery System

PURPOSE

Demonstrate in vivo that controlled and extended release of a low dose of anti-vascular endothelial growth factor (anti-VEGF) from a microsphere-hydrogel drug delivery system (DDS) has a therapeutic effect in a laser-induced rat model of choroidal neovascularization (CNV).

METHODS

Anti-VEGF (ranibizumab or aflibercept) was loaded into poly(lactic-co-glycolic acid) microspheres that were then suspended within an injectable poly(N-isopropylacrylamide)-based thermo-responsive hydrogel DDS.The DDS was shown previously to release bioactive anti-VEGF for ~200 days. CNV was induced using an Ar-green laser. The four experimental groups were as follows: (i) non-treated, (ii) drug-free DDS, (iii) anti-VEGF-loaded DDS, and (iv) bolus injection of anti-VEGF. CNV lesion areas were measured based on fluorescein angiograms and quantified using a multi-Otsu thresholding technique. Intraocular pressure (IOP) and dark-adapted electroretinogram (ERG) were also obtained pre- and post-treatment (1, 2, 4, 8, and 12 weeks).

RESULTS

The anti-VEGF-loaded DDS group had significantly smaller (60%) CNV lesion areas than non-treated animals throughout the study. A small transient increase in IOP was seen immediately after injection; however, all IOP measurements at all time points were within the normal range. There were no significant changes in ERG maximal response compared to pre-treatment measurements for the drug-loaded DDS, which suggests no adverse effects on retinal cellular function.

CONCLUSIONS

The current study demonstrates that the DDS can effectively decrease laser-induced CNV lesions in a murine model. Controlled and extended release from our DDS achieved greater treatment efficacy using an order of magnitude less drug than what is required with bolus administration. This suggests that our DDS may provide a significant advantage in the treatment of posterior segment eye diseases.

Affinity of Indocyanine Green in the Detection of Colorectal Peritoneal Carcinomatosis

Indocyanine green (ICG) is increasingly being used in digestive oncology. In colorectal cancer, ICG can be used to detect lymph node metastasis and hepatic metastasis on the surface of the liver. In peritoneal carcinomatosis, it was previously suspected that the diffusion of ICG in the tumor mass was due to the enhanced permeability and retention effect; however, this phenomenon has not been clearly demonstrated. Using bevacizumab, an antibody directed against vascular endothelial growth factor that consequently inhibits neoangiogenesis, we sought to confirm the mode of ICG diffusion. We compared the fluorescence of peritoneal carcinomatosis nodules from patients who had previously received bevacizumab during their oncologic treatment with those who did not receive this therapy. The sensitivity of the carcinomatosis nodule fluorescence was higher in the patients who did not receive bevacizumab compared with those who received the drug (76.3% and 65.0%, respectively). The rate of false-negative results was higher in the bevacizumab group than in the group that did not receive the drug (53.8% and 42.9%, respectively). Using bevacizumab, we demonstrate that the enhanced permeability and retention effect causes ICG accumulation in peritoneal carcinomatosis resulting from colorectal cancer.

Minimizing projection artifacts for accurate presentation of choroidal neovascularization in OCT micro-angiography

Current optical coherence tomography (OCT) based micro-angiography is prone to a projection (or tailing) effect due to the high scattering property of blood within overlying patent vessels, creating artifacts that interfere with the interpretation of retinal angiographic results. In this work, the projection effect in OCT micro-angiography is examined and its causality is explained by strong light scattering and photon propagation within blood. A simple practical approach is then introduced to minimize these artifacts presented in the outer retinal avascular space, especially useful for examining clinical cases with choroidal neovascularization (CNV). Demonstrated through in-vivo human posterior eye imaging of healthy and CNV subjects, the proposed method is shown effective to eliminate the projection artifacts in outer retinal space of OCT micro-angiography, resulting in better visualization of the pathological neovascularization when compared with the current common approaches. In addition, it is also shown that the proposed method is applicable to minimize the projection artifacts appearing in deep retinal layers.

A rat model for choroidal neovascularization using subretinal lipid hydroperoxide injection

The purpose of this study was to develop and characterize a rat model of choroidal neovascularization (CNV) as occurs in age-related macular degeneration. The lipid hydroperoxide 13(S)-hydroperoxy-9Z,11E-octadecadienoic acid (HpODE) is found in submacular Bruch's membrane in aged humans and has been reported to generate neovascularization in a rabbit model. Three weeks after a single subretinal injection of 30 microg of HpODE, eyes of Sprague-Dawley rats were harvested. Follow-up fluorescein angiography was done on other animals until 5 weeks postinjection. Histological studies, immunohistochemical staining, and flatmount choroids for CNV measurements were performed. In addition, we used murine neuronal, bovine endothelial, and human ARPE19 cells for testing the in vitro effects of HpODE. CNV developed in 85.7% of HpODE-injected eyes. The neovascular areas were significantly greater in HpODE-injected eyes compared with those in control eyes (P = 0.023). The CNV had maximum dye leakage at 3 weeks, which subsided by the 5th week. Histologically, CNV extended from the choriocapillaris into the subretinal space. ED1-positive macrophages were recruited to the site. In vitro assays demonstrated that only 30 ng/ml HpODE induced cell proliferation and migration of endothelial cells. HpODE-induced CNV was highly reproducible, and its natural course seems to be ideal for evaluating therapeutic modalities. Because HpODE has been isolated from aged humans, the HpODE-induced rat model seems to be a relevant experimental model for CNV in age-related macular degeneration.

Early subfoveal choroidal neovascularization secondary to an accidental stage laser injury

PURPOSE

To report a case of early subfoveal choroidal neovascularization secondary to an accidental stage laser injury.

METHODS

A 22-year-old female technician complained of visual loss and an immovable shadow in her right central vision after being irradiated accidentally by a laser light beam with a wavelength of 532 nm while aligning a stage laser light. She underwent a full ophthalmologic examination 5 days later; including visual acuity, color fundus photography and fluorescein angiography. Eight months later these examinations were repeated, accompanied by optical coherence tomography.

RESULTS

Best-corrected visual acuity in her right eye was 0.08 at 5 days after the injury and hand motion 8 months later; acuity remained at 1.2 in the left throughout follow-up. A small grayish-yellow lesion with exudation was present at the foveal area in the right eye 5 days after the injury. Eight months later the lesion had enlarged and hemorrhage had appeared. A classic choroidal neovascularization was detected in the subfovea on both fluorescein angiography and optical coherence tomography. Another 4 months later the visual acuity had increased to 0.01. Funduscopic examination revealed the lesion unchanged and the hemorrhage diminished.

CONCLUSIONS

Stage laser light with a wavelength of 532 nm may cause early subfoveal choroidal neovascularization when used inappropriately.

Selective occlusion of subfoveal choroidal neovascularization in angioid streaks by using a new technique of ingrowth site treatment

PURPOSE

To evaluate the visual and angiographic effects, as well as optical coherence tomography (OCT) findings, after a new treatment-neovascular ingrowth-site photothrombosis-in patients with subfoveal choroidal neovascularization (CNV) secondary to angioid streaks.

DESIGN

Prospective noncomparative small case series.

PARTICIPANTS

Five eyes of 5 patients with angioid streaks in whom fluorescein and conventional indocyanine green (ICG) angiography clearly demonstrated distinct CNV vessels supplying the subfoveal neovascular complex.

INTERVENTION

All five eyes were submitted to ICG-mediated photothrombosis of the neovascular ingrowth site. This novel, laser/dye-mediated technique uses large-spot, lower-intensity 810-nm light for continuous application of laser energy to ICG concentrated in vascular lesions.

MAIN OUTCOME MEASURES

Visual outcome and the results of fluorescein angiography, ICG angiography, and OCT evaluation.

RESULTS

Fluorescein and conventional ICG angiography were sufficient to identify the CNV ingrowth site, which was juxtafoveal in 2 and extrafoveal in 3 of the 5 eyes in this series. Obliteration of the entire neovascular lesion was achieved in all patients within the first hour after ICG-mediated photothrombosis of the CNV ingrowth site. At 1 week, the mean change in best-corrected visual acuity from baseline was +3.2 (+/-1.4) lines. Twelve months after treatment, visual acuity improved by 3 or more lines in all patients, and decreased leakage of fluorescein from the CNV, as well as OCT evidence of reduced or resolved retinal edema, was seen at the last follow-up visit. Major complications, such as immediate severe visual loss and retinal vessel occlusion in the early posttreatment period, were not identified in the 5 patients submitted to the procedure.

CONCLUSIONS

Photothrombosis of the CNV ingrowth site by using lower-intensity light to direct laser energy continuously after IV ICG infusion is a safe and effective technique for rapid induction of CNV hypoperfusion in selected patients and is associated with considerable improvement in visual acuity and partial restoration of the retinal architecture up to 12 months after treatment.

Inhibition of experimental choroidal neovascularization by irsogladine, an anti-gastric ulcer agent

PURPOSE

To determine whether irsogladine inhibits experimental choroidal neovascularization (CNV) induced by laser photocoagulation in pigmented rats.

METHODS

Focal laser photocoagulation (argon green 50 mW, 0.04 s, 200 microm) was applied to the retinochoroid of normal Brown Norway rats. Oral administration of irsogladine (5 mg/kg/day or 50 mg/kg/day) was started 1 week before and continued for 2 weeks after laser photocoagulation. Choroidal vascular casts were made 2 weeks after laser photocoagulation and were examined with a scanning electron microscope (SEM). CNV formation was classified according to three grades and evaluated.

RESULTS

Laser-induced CNV formation was significantly reduced in rats given 5 mg/kg/day (p < 0.01) or 50 mg/kg/day of irsogladine (p < 0.001). Administration of 50 mg/kg/day of irsogladine was more effective in preventing CNV formation than 5 mg/kg/day (p < 0.001). The development of the vascular bud was especially inhibited by 50 mg/kg/day of irsogladine (p < 0.001). CNVs in rats treated with 50 mg/kg/day of irsogladine looked less well developed than those in controls. There was no significant side effect of irsogladine.

CONCLUSIONS

Irsogladine inhibits the development of experimental CNV induced by photocoagulation in pigmented rats.