van Best J A, Putting B J, Oosterhuis J A, Zweypfenning R C, Vrensen G F
Department of Ophthalmology, Leiden University Hospital, The Netherlands.
Microsc Res Tech. 1997 Jan 15;36(2):77-88. doi: 10.1002/(SICI)1097-0029(19970115)36:2<77::AID-JEMT1>3.0.CO;2-S.
The purpose of this study was to determine the threshold energy for light-induced functional damage of the retinal pigment epithelium at various wavelengths. Retinas of 58 pigmented and 21 albino rabbits were exposed to low intensity broadband blue light (400-520 nm), yellow light (510-740 nm), and narrowband blue light (408, 417, 439, 455, 485, 501 nm, respectively; deltalambda = 10-13 nm). The intensity values were 50, 280, and 5 mW x cm (-2), respectively, and the illumination time was 0.5 up to 5 h. The cumulative dose of light energy was calculated from these data (J x cm(-2)). The blood-retinal barrier dysfunction was evaluated in vivo using fluorophotometry to measure the leakage of fluorescein into the vitreous after intravenous injection and in vitro using light and electron microscopy after an in vivo intraarterial injection of horseradish peroxidase (HRP). The threshold energy for fluorescein leakage was 50 J x cm (-2) for blue light and 1,600 J x cm(-2) for yellow light. After broadband blue light exposure, the HRP reaction product was seen in the cytoplasm of the retinal pigment epithelium (RPE) cells and in the subretinal space but only if fluorescein leakage had been observed. Threshold energy and fluorescein leakage as a function of light energy were similar for albino and pigmented rabbits (P > 0.5). Only after yellow light exposure in excess of 3,700 J x cm(-2) was fluorescein leakage found. In that case complete disruption of the RPE was seen, but no HRP was observed in the RPE cytoplasm. Of the narrow-band blue light exposures, only that at lambda = 418 nm caused a significant increase in fluorescein leakage; the threshold energy was 18 J x cm(- 2). Blue light was found to be at least 30 times more efficient than yellow light in causing dysfunction of the blood-retinal barrier. The most efficient wavelength was 418 nm, corresponding with the absorption spectrum of cytochrome c oxidase. Melanin seemed to play no role. The presence or absence of melanin in the RPE appeared to have no influence on the threshold energy.
本研究的目的是确定不同波长下光诱导视网膜色素上皮功能损伤的阈值能量。对58只有色家兔和21只白化家兔的视网膜进行低强度宽带蓝光（400 - 520 nm）、黄光（510 - 740 nm）和窄带蓝光（分别为408、417、439、455、485、501 nm；Δλ = 10 - 13 nm）照射。强度值分别为50、280和5 mW·cm⁻²，照射时间为0.5至5小时。根据这些数据计算光能的累积剂量（J·cm⁻²）。采用荧光光度法在体内评估血视网膜屏障功能障碍，即静脉注射荧光素后测量荧光素向玻璃体的渗漏情况；在体内动脉注射辣根过氧化物酶（HRP）后，采用光学显微镜和电子显微镜在体外评估血视网膜屏障功能障碍。蓝光导致荧光素渗漏的阈值能量为50 J·cm⁻²，黄光为1600 J·cm⁻²。宽带蓝光照射后，仅在观察到荧光素渗漏时，才在视网膜色素上皮（RPE）细胞的细胞质和视网膜下间隙中看到HRP反应产物。白化家兔和有色家兔的阈值能量和作为光能函数的荧光素渗漏情况相似（P > 0.5）。仅在黄光照射超过3700 J·cm⁻²后才发现荧光素渗漏。在这种情况下，可见RPE完全破坏，但在RPE细胞质中未观察到HRP。在窄带蓝光照射中，仅波长为418 nm的照射导致荧光素渗漏显著增加；阈值能量为18 J·cm⁻²。发现蓝光导致血视网膜屏障功能障碍的效率至少是黄光的30倍。最有效的波长为418 nm，与细胞色素c氧化酶的吸收光谱相对应。黑色素似乎不起作用。RPE中黑色素的存在与否似乎对阈值能量没有影响。
