Some patients may be asymptomatic because they avoid carrying out those tasks which result in asthenopia, in other words the presence or absence of symptoms cannot always be relied up to help in the differential diagnosis of a decompensated heterophoria.

In the history and symptoms it may be appropriate in some cases to ask if the patient avoids doing any tasks because of eye problems. Classically, some children and young adults avoid reading because of visual discomfort and therefore on first questioning may seem to be asymptomatic.

They have stopped doing whatever it was that caused them to have eye aches and/or headaches.