St. Thomas' Hospital, Westminster Bridge Road, London, UK SE1 7EH.
Graefes Arch Clin Exp Ophthalmol. 2013 Jan;251(1):35-9. doi: 10.1007/s00417-012-2033-5. Epub 2012 May 6.
There is sudden and dramatic visual function deterioration in 1-10 % of eyes filled with silicone oil at the time of removal of silicon oil. Transmission of high-energy blue light is increased in eyes filled with silicone oil. We sought to identify if increased foveal light exposure is a potential factor in the pathophysiology of the visual loss at the time of removal of silicone oil.
A graphic ray tracing computer program and laboratory models were used to determine the effect of the intraocular silicone oil bubble size on the foveal illuminance at the time of removal of silicone oil under direct microscope light. The graphic ray tracing computer program revealed a range of optical vignetting effects created by different sizes of silicone oil bubble within the vitreous cavity giving rise to an uneven macular illumination. The laboratory model was used to quantify the variation of illuminance at the foveal region with different sizes of silicone oil bubble with in the vitreous cavity at the time of removal of silicon oil under direct microscope light. To substantiate the hypothesis of the light toxicity during removal of silicone oil, The outcome of oil removal procedures performed under direct microscope illumination in compared to those performed under blocked illumination.
The computer program showed that the optical vignetting effect at the macula was dependent on the size of the intraocular silicone oil bubble. The laboratory eye model showed that the foveal illuminance followed a bell-shaped curve with 70 % greater illuminance demonstrated at with 50-60 % silicone oil fill. The clinical data identified five eyes with unexplained vision loss out of 114 eyes that had the procedure performed under direct microscope illumination compared to none out of 78 eyes that had the procedure under blocked illumination.
Foveal light exposure, and therefore the potential for phototoxicity, is transiently increased at the time of removal of silicone oil. This is due to uneven macular illumination resulting from the optical vignetting effect of different silicone oil bubble sizes. The increase in foveal light exposure may be significant when the procedure is performed under bright operating microscope light on already stressed photoreceptors of an eye filled with silicon oil. We advocate the use of precautions, such as central shadow filter on the operating microscope light source to reduce foveal light exposure and the risk of phototoxicity at the time of removal of silicone oil. The graphic ray tracing computer program used in this study shows promise in eye modeling for future studies.
在取出硅油时，有 1-10%的填充硅油的眼睛会突然出现戏剧性的视力恶化。填充硅油的眼睛中高能蓝光的传输增加。我们试图确定在取出硅油时，黄斑光暴露增加是否是视觉丧失的病理生理学中的一个潜在因素。
使用图形光线追踪计算机程序和实验室模型来确定在直接显微镜光下取出硅油时，眼内硅油气泡大小对黄斑照度的影响。图形光线追踪计算机程序揭示了不同尺寸的硅油气泡在玻璃体腔内产生的一系列光学渐晕效应，导致黄斑照明不均匀。实验室模型用于定量测量在直接显微镜光下取出硅油时，玻璃体腔内不同大小的硅油气泡对黄斑区域照度的变化。为了证实取出硅油过程中的光毒性假说，将直接显微镜照明下进行的油去除程序的结果与在阻塞照明下进行的油去除程序的结果进行了比较。
计算机程序显示，黄斑的光学渐晕效应取决于眼内硅油气泡的大小。实验室眼球模型显示，黄斑照度呈钟形曲线，50-60%硅油填充时，照度增加 70%。临床数据显示，在 114 只直接显微镜照明下进行手术的眼中，有 5 只眼睛视力下降原因不明，而在 78 只阻塞照明下进行手术的眼中，没有一只眼睛视力下降。
在取出硅油时，黄斑光暴露增加，因此存在光毒性的潜在风险。这是由于不同硅油气泡大小的光学渐晕效应导致黄斑照明不均匀。当在充满硅油的眼睛已经处于应激状态的感光器上，用明亮的手术显微镜进行手术时，黄斑光暴露的增加可能会很显著。我们主张使用预防措施，如在手术显微镜光源上使用中央阴影滤波器，以减少取出硅油时的黄斑光暴露和光毒性风险。本研究中使用的图形光线追踪计算机程序在眼球建模方面具有很大的潜力，可用于未来的研究。
