Safran A B, Bader C, Brazitikos P D, de Weisse C, Désangles D
Neuro-Ophthalmology Unit, Geneva University Hospital, Switzerland.
Am J Ophthalmol. 1992 Feb 15;113(2):193-7. doi: 10.1016/s0002-9394(14)71534-x.
An increase in short-term fluctuation is a clinically useful clue in the diagnosis of acquired disorders of the visual pathways. However, short-term fluctuation can also be increased in normal subjects by several factors. We found an increase in short-term fluctuation occurred in normal subjects when the visual field was tested using a bright fixation aid. Eight normal subjects underwent automated perimetry with the Octopus 2000R, in which the dimmest (12.5 candelas/m2) and brightest (435 cd/m2) available fixation aids were used. Mean short-term fluctuation values were 1.63 +/- 0.27 dB with the dimmest aid, and were 2.65 +/- 1.26 dB with the brightest aid. The difference was significant using the paired t-test (P = .037). Moreover, mean sensitivity was reduced from 35.67 +/- 2.26 dB to 33.66 +/- 1.71 dB when the brightest fixation aid was used (P = .004). In six of eight subjects, the relative changes in short-term fluctuation after an increase in brightness of the fixation aid were more pronounced than those in mean sensitivity. An increase in intensity of the fixation aid may cause visual changes in normal subjects that resemble those induced by disorders in the visual pathways. Whenever possible, minimal intensity of the fixation aid should be used to allow for an adequate interpretation of short-term fluctuation values.
短期波动增加是诊断后天性视觉通路疾病的一个临床有用线索。然而，正常受试者的短期波动也可能因多种因素而增加。我们发现，当使用明亮的固视辅助工具测试视野时，正常受试者的短期波动会增加。8名正常受试者使用Octopus 2000R进行自动视野检查，其中使用了最暗（12.5坎德拉/平方米）和最亮（435坎德拉/平方米）的固视辅助工具。使用最暗辅助工具时，平均短期波动值为1.63±0.27 dB，使用最亮辅助工具时为2.65±1.26 dB。采用配对t检验，差异具有统计学意义（P = 0.037）。此外，使用最亮的固视辅助工具时，平均敏感度从35.67±2.26 dB降至33.66±1.71 dB（P = 0.004）。在8名受试者中的6名中，固视辅助工具亮度增加后短期波动的相对变化比平均敏感度的变化更明显。固视辅助工具强度的增加可能会在正常受试者中引起类似于视觉通路疾病所诱发的视觉变化。只要有可能，应使用最低强度的固视辅助工具，以便对短期波动值进行充分解读。
