One should always examine both eyes. This can be very helpful in patients with presumed pupillary block angle closure in one eye. If corneal edema precules a view of the iridocorneal angle looking at the fellow eye can be instructive. If the opposite eye has a wide-open angle one might need to reconsider diagnosis. Similarly, angle recession can be difficult to differentiate from the deep anterior chambers of highly myopic eyes. Comparing the two eyes can help to make the appropriate diagnosis.