HMME-PDT药物剂量和光剂量对正常视网膜和脉络膜结构的影响

Influence of drug and light dosage on normal retina and choroid structure during HMME-PDT

目的观察血卟啉单甲醚-光动力疗法(HMME-PDT)过程中不同药物剂量和激光剂量对照光区域视网膜和脉络膜组织结构的影响。方法以新西兰兔为实验动物,药物剂量分别为2.5、5和10mg/kg体重耳缘静脉注射,在注射药物结束后5min内分别使用光斑能量密度5、20、40和60J/cm2进行照射,并在第1d、7d行眼底观察、荧光素眼底血管造影(FAA)和组织病理学方法检测照射部位的结构变化。结果在3种药物剂量、4种能量密度情况下,在PDT后第1d都有脉络膜毛细血管闭塞现象发生。随着药物剂量和激光剂量的增加,发生脉络膜毛细血管闭塞的光斑增多,维持到第7d。结论提高药物剂量或能量密度能够促进并保持脉络膜毛细血管闭塞,但同时使非选择性损伤加重。药物剂量和激光剂量的良好匹配能获得良好治疗效果,而同时对视网膜损伤最小。

Objective Aging macular degeneration （AMD） is one of the most common reasons leading to visual loss in elder population. Photodynamic therapy is an effective approach to treating AMD. The present study was to observe the microstructural change of retina and choroid following different dye and laser dosage irradiation during hematoporphyrin mono methyl ether photodynamic therapy （HMME-PDT）. Methods Fundi of the normal New Zealand rabbits were irradiated by 532 nm laser with a fluence of 5, 20, 40 and 60 J/cm^2 within 5 minutes after the drug injection of 2.5, 5 and 10 mg/kg from the marginal ear vein. At the 1 st and 7 th day after PDT, the structural alteration of irradiated retina and choroid was observed by funduscope, fundus fluorescein angiography （FFA） and histological examination. Results At day 1 after PDT, the irradiated area became whitish and showed hyperfluorescein, the choriodal capillaries of some irradiated area became occlusive at above different dye dose and four laser dose under the light microscope. In the 7 th day, the whitish retina was gradually recovered, and the occlusive choriocapillaris could be clearly seen to be hypofluorescein by FFA. Conclusion Higher dosage of light irradiation or drug induces more desirable effect but is likely to bring damage of adjacent normal structure. The maximal matching of used drug and light dose will be a valid approach to reaching the satisfactory therapeutic effect sparing the normal retina.