Panjaphongse Ronakorn, Liu Weifeng, Pongsachareonnont Pear, Stewart Jay M
1 Department of Ophthalmology, University of California , San Francisco, San Francisco, California.
J Ocul Pharmacol Ther. 2015 Apr;31(3):174-8. doi: 10.1089/jop.2014.0134. Epub 2015 Jan 8.
To analyze the kinematics of a dexamethasone intravitreal implant, Ozurdex, after its injection in a balanced salt solution (BSS) at different release angles to simulate its movement in BSS/aqueous-filled eyes.
Eighteen Ozurdex implants were injected into a BSS-filled box at different release angles (15°, 30°, 45°), using 6 implants/group. The movement of injected implants was recorded by a high-speed video camera. Each implant's trajectory was graphically demonstrated by plotting over time. By using a distance-time function graph, the implant's velocity and normalized energy were calculated.
The high-speed video revealed that implants injected at 15° followed a more horizontal trajectory compared to those injected from 30° and 45°, respectively. The implant injected at 15° also achieved the highest mean initial velocity and mean initial normalized energy. The implant velocity from each injection angle decreased exponentially over time and reached nearly zero at 0.1 s. An injection of the implant at a flatter angle was also associated with higher mean retinal impact normalized energy.
An implant injected at a flatter angle tends to travel farther in the horizontal plane and has more initial velocity, which theoretically generates higher initial normalized energy and retinal impact normalized energy. The accidental injection at a flatter angle, which results in shortening of the effective travel distance, may carry the potential risk of direct retinal injury from the injected implant. The amount of energy necessary to cause direct retinal injury, and whether this would be clinically significant, requires further study.
分析地塞米松玻璃体内植入剂Ozurdex在平衡盐溶液（BSS）中以不同释放角度注射后，模拟其在充满BSS/房水的眼中的运动的运动学情况。
将18个Ozurdex植入剂以不同释放角度（15°、30°、45°）注射到充满BSS的盒子中，每组6个植入剂。通过高速摄像机记录注射后植入剂的运动。通过随时间绘制图表，以图形方式展示每个植入剂的轨迹。利用距离-时间函数图，计算植入剂的速度和归一化能量。
高速视频显示，与分别从30°和45°注射的植入剂相比，以15°注射的植入剂的轨迹更水平。以15°注射的植入剂还实现了最高的平均初始速度和平均初始归一化能量。每个注射角度的植入剂速度随时间呈指数下降，并在0.1秒时几乎降至零。以更平缓角度注射植入剂也与更高的平均视网膜撞击归一化能量相关。
以更平缓角度注射的植入剂在水平面上倾向于移动得更远，并且具有更高的初始速度，从理论上讲会产生更高的初始归一化能量和视网膜撞击归一化能量。以更平缓角度意外注射会导致有效移动距离缩短，可能会带来注射的植入剂直接损伤视网膜的潜在风险。造成直接视网膜损伤所需的能量大小以及这在临床上是否具有重要意义，需要进一步研究。
