No abstract

Purpose Corneal neovascularization (CNV) is the invasion of new blood vessels into the avascular cornea, leading to reduced corneal transparency and visual acuity, impaired vision, and even blindness. Current treatment options for CNV are limited. We developed a novel treatment method, termed photo-mediated ultrasound therapy (PUT), that combines laser and ultrasound, and we tested its feasibility for treating CNV in a rabbit model. Methods A suture-induced CNV model was established in New Zealand White rabbits, which were randomly divided into two groups: PUT and control. For the PUT group, the applied light fluence at the corneal surface was estimated to be 27 mJ/cm 2 at 1064-nm wavelength with a pulse duration of 5 ns, and the ultrasound pressure applied on the cornea was 0.43 MPa at 0.5 MHz. The control group received no treatment. Red-free photography and fluorescein angiography were utilized to evaluate the efficiency of PUT. Safety was evaluated by histology and immunohistochemistry. For comparison with the PUT safety results, conventional laser photocoagulation (LP) treatment was performed with standard clinical parameters: 532-nm continuous-wave (CW) laser with 0.1-second pulse duration, 450-mW power, and 75-µm spot size. Results In the PUT group, only 1.8% ± 0.8% of the CNV remained 30 days after treatment. In contrast, 71.4% ± 7.2% of the CNV remained in the control group after 30 days. Safety evaluations showed that PUT did not cause any damage to the surrounding tissue. Conclusions These results demonstrate that PUT is capable of removing CNV safely and effectively in this rabbit model. Translational Relevance PUT can remove CNV safely and effectively.

Objectives: Retinal neovascularization (RNV) is the growth of abnormal microvessels on the retinal surface and into the vitreous, which can lead to severe vision loss. By combining relatively low-intensity ultrasound and nanosecond-pulse-duration laser, we developed a novel treatment method, namely photo-mediated ultrasound therapy (PUT), which holds a potential to remove RNV with minimal or no damage to the adjacent tissues. Methods: RNV was created in both albino and pigmented rabbits (n = 10) through a single intravitreal injection with DL-α-aminoadipic acid. RNV was treated with PUT 8 weeks postinjection. After PUT treatment, animals were evaluated longitudinally for up to 6 weeks. Treatment outcomes were evaluated through fundus photography, red-free fundus photography, fluorescein angiography (FA), and histopathology. Results: In both albino and pigmented rabbits, there were no leakage in the treatment area immediately after PUT treatment as demonstrated by FA, indicating the cessation of blood perfusion of the RNV in the treated area. The fluorescence leakage did not recover in albino rabbits during the 6-week posttreatment monitoring period, and only 9.9 ± 9.8% of the neovascularization remained at the end of 6 weeks. In the pigmented rabbits, the fluorescence leakage partially returned, but the level of leakage decreased over time during the 6-week posttreatment monitoring period, and only 10.8 ± 9.8% of the neovascularization remained at the end of 6 weeks. Histology demonstrated removal of vasculature without damage to the surrounding neurosensory retina. Conclusions: These results demonstrate that PUT could precisely remove RNV without damage to the surrounding neurosensory retina in both rabbit strains.