Abstract
Purpose :
Corneal neovascularization (CNV) causes blindness in 7 million people worldwide. Laser photocoagulation treatment (LPT) results in transient treatment effects with numerous side effects, including hemorrhage, corneal thinning, and damage surrounding tissues. A novel, controllable, imaging-guided photo-mediated ultrasound therapy (PUT) is developed. PUT can selectively treat blood vessels using synchronized low intensity nanosecond pulse duration laser and ultrasound without damaging surrounding tissue under real-time image guidance.
Methods :
An integrated therapeutic ultrasound (0.5 MHz bursts of 10% duty cycle at a rate of 10 Hz, H107 Sonic Concepts, Bothell, WA), laser treatment system and CCD camera system was devised. A standard Nd:YAG laser (Continuum Powerlite DLS 8010) was employed to produce laser pulses with 5-ns pulse duration, 10-Hz pulse repetition rate at a wavelength of 1064 nm at the beginning of each ultrasound burst focused on the cornea with 3 millimeters spot size. LPT was performed using the Vitra 532 Photocoagulator using settings of 0.1 millisecond pulse duration, 75 μm spot size, and 450 mW power. New Zealand white rabbits (n=21) were treated with one 7-0 nylon suture surgically placed into the cornea to generate a rabbit CNV model. 9 rabbits were treated with multiple PUT settings, 6 rabbits were treated with LPT, and the remaining 6 served as controls. The animals were monitored for up to 4 weeks after PUT with anterior segment photography, red free photography, and fluorescein angiography (FA).
Results :
In the PUT group, the corneal neovascularization in the treated area was selectively removed without causing collateral tissue damage to the corneal stroma, epithelium, limbus, or endothelium. In the LPT group, the corneal neovascularization can be removed transiently, but significant damage to the surrounding tissue are noted. In the control group, the corneal neovascularization remained largely stable over 4 weeks. After 30 days, 71.4%±7.2% neovascular was left in control group, compared to 28.6%±12.5% in LPT group,1.8%±0.8% in PUT group.
Conclusions :
The experimental results demonstrate that PUT can selectively treat corneal neovascularization without damaging the surrounding tissue. This could offer significant advantage in improving the clinical management of eye diseases by selectively treating of pathologic vessels with minimized side effects.
This is a 2020 ARVO Annual Meeting abstract.