非消融性193纳米准分子激光辐射所致的光性角膜炎

Krueger R R, Sliney D H, Trokel S L

Harkness Eye Institute, Columbia-Presbyterian Medical Center, New York, NY.

Refract Corneal Surg. 1992 Jul-Aug;8(4):274-9.

BACKGROUND

Photokeratitis is a side effect of UV light exposure whereby the corneal epithelium is photochemically injured in a time delayed fashion. UV light exposure in the far ultraviolet wavelength range has not previously been observed. This study addresses the concern of photokeratitis from subablative 193-nanometer excimer laser light.

METHODS

Dutch belted rabbit corneas were irradiated with subablative 193-nanometer excimer laser light over a wide range of total energy exposures, and examined by slit lamp biomicroscope for signs of photokeratitis. Photokeratitis was identified by epithelial haze and stippling, and rose bengal and fluorescein staining at varied time intervals between 1/2 to 26 hours post exposure.

RESULTS

At threshold energy exposures of 1.0 to 1.5 J/cm2, an immediate superficial epithelial haze was seen which disappeared within several hours. At higher energy exposures of 10 J/cm2, a delayed photokeratitis with deep rose bengal and even fluorescein staining was seen. This latter delayed photokeratitis resembles that of longer UV wavelengths and is due to excimer laser fluorescence, whereas the former is a direct response of the 193-nanometer light. The percentage of excimer laser light undergoing fluorescence is calculated as less than 1%.

CONCLUSIONS

The potential side effects and hazards of scattered 193-nanometer radiation during excimer laser surgery are extremely limited because of the shorter penetration depth of direct excimer radiation and the minimal fluorescent emission of longer UV wavelengths for energy exposures within the realm of clinical use.

背景

光性角膜炎是紫外线暴露的一种副作用，在此过程中角膜上皮会以时间延迟的方式受到光化学损伤。此前尚未观察到远紫外线波长范围内的紫外线暴露情况。本研究探讨了准分子激光非消融性193纳米激光照射引发光性角膜炎的问题。

方法

用准分子激光非消融性193纳米激光对荷兰带兔角膜进行广泛的总能量照射，并用裂隙灯显微镜检查光性角膜炎的迹象。通过上皮混浊和点染，以及在暴露后1/2至26小时的不同时间间隔进行孟加拉玫瑰红和荧光素染色来确定光性角膜炎。

结果

在阈值能量照射为1.0至1.5 J/cm²时，可见立即出现的浅层上皮混浊，数小时内消失。在更高能量照射为10 J/cm²时，可见延迟性光性角膜炎，伴有深层孟加拉玫瑰红染色和均匀的荧光素染色。后一种延迟性光性角膜炎类似于较长紫外线波长引起的情况，是由于准分子激光荧光所致，而前者是193纳米光的直接反应。经计算，发生荧光的准分子激光光的百分比小于1%。