Jamara Richard J, Van De Velde Frans, Peli Eli
Department of Specialty and Advanced Care, New England College of Optometry, Boston, Massachusetts, USA.
Optom Vis Sci. 2003 Jul;80(7):495-504. doi: 10.1097/00006324-200307000-00011.
Sparing or partial recovery of visual fields in hemianopic patients is frequently difficult to document. This is because when testing large field losses, the standard automated or manual visual field testing systems have limited fixation controls. Measured visual field recovery in these cases may not be real but instead may be due to an artifact such as scanning eye movement. This article illustrates a way to separate the actual visual field sparing from scanning eye movement artifact by using perimetry testing with the scanning laser ophthalmoscope (SLO). During the SLO perimetry, the examiner has a direct and magnified view of the retinal fixation locus. This direct view allows for the added ability to monitor the fixation stability during target presentation. When eye movements larger than 1 degrees are noted, the examiner can repeat the trial. During static perimetry, our SLO records the retinal position of the fixation target at the end of the stimulus presentation and corrects scanning eye movements that occur during stimulus presentation. These special features enable us to identify when the apparent sparing of the visual field is due to the artifact of scanning. To demonstrate this, we selected the records of four hemianopic patients whose fields were examined by both standard perimetry and the SLO. We then compared the clinical visual fields with the SLO perimetry fields. One of the patients had a complete homonymous hemianopia on both the clinical perimetry and the SLO perimetry. A second patient was found by the SLO to have unstable fixation during testing. The SLO perimetry revealed that the apparent spared fields seen in standard perimetry were the result of eye scanning and not an actual enlargement of the visual field. Two other patients were confirmed by the SLO findings to have valid partial recovery of the visual field, one with and one without scanning eye movements. The advantages and limitations of SLO perimetry in analyzing hemianopic field sparing are discussed.
偏盲患者视野的保留或部分恢复情况常常难以记录。这是因为在检测大范围视野缺损时，标准的自动或手动视野检测系统的注视控制能力有限。在这些情况下测得的视野恢复可能并非真实情况，而可能是由诸如眼球扫描运动等伪迹导致的。本文阐述了一种通过使用扫描激光检眼镜（SLO）进行视野检查来区分实际的视野保留与眼球扫描运动伪迹的方法。在SLO视野检查过程中，检查者可以直接且放大地观察视网膜注视位点。这种直接观察使得在呈现目标时能够额外监测注视稳定性。当发现眼球运动大于1度时，检查者可以重复试验。在静态视野检查期间，我们的SLO会在刺激呈现结束时记录注视目标的视网膜位置，并校正刺激呈现期间发生的眼球扫描运动。这些特殊功能使我们能够识别视野的明显保留何时是由扫描伪迹引起的。为了证明这一点，我们选择了四名偏盲患者的记录，他们的视野通过标准视野检查和SLO都进行了检查。然后我们将临床视野与SLO视野检查结果进行了比较。其中一名患者在临床视野检查和SLO视野检查中均表现为完全同向偏盲。第二名患者在SLO检查中被发现测试期间注视不稳定。SLO视野检查显示，在标准视野检查中看到的明显保留视野是眼球扫描的结果，而非实际视野扩大。另外两名患者经SLO检查结果证实有有效的视野部分恢复，其中一名有眼球扫描运动，一名没有。文中还讨论了SLO视野检查在分析偏盲视野保留方面的优势和局限性。
