Normal 10-2 Visual Fields Over Time
The most important ancillary test used in hydroxychloroquine screening is the 10-2 visual field. For it to be useful, one must be aware of the normal range of variability of the test over time. This series of three 10-2 visual fields taken over a four year interval shows that the points in the visual field with abnormally high thresholds are not reproducible from study to study. Note the paired red arrows and the paired green arrows. In the top field from 3-6-2007, the point indicated by the red arrow has an elevated threshold seen normally in <2% of normal subjects (see the symbol legend at the bottom). This same point has a normal threshold in the follow-up field of 10-21-2009. Now there is a new point, indicated with the green arrow, with an elevated threshold seen normally in <5% of normal subjects. However, in the follow-up field of 10-7-2011, this same point has reverted to normal. Persistent elevated thresholds at the same points would indicated an abnormality. Inconsistent, isolated points with elevated thresholds are commonly seen in 10-2 visual fields of normal subjects.