Numerous ancillary studies can be performed on a patient with strabismus. This section covers some of the more common tests that are readily available.
It is often useful to determine if a patient has the potential to fuse, especially if surgery is anticipated. This can be determined with prism correction of the deviation or with an amblyoscope
Patients with good motor fusional amplitudes are more likely to be able to fuse following surgery.
Each of the cyclovertical muscles has a complex set of primary and secondary actions including torsional ocular movements. Therefore, testing for the presence of a concurrent cyclotropia is important in the management of a patient with vertical strabismus. Cyclotorsion can be estimated objectively by evaluation of the fundus for evidence of cyclotorsion and can be measured subjectively with double Maddox rods. Use of Double Maddox Rod Test to Assess Cyclotropia Binocular Visual Field Testing This test can be useful in quantifying the size and location of the field of single binocular vision in a patient who is able to achieve fusion in some positions of gaze. Binocular Visual Field Assessment Using a Goldmann Perimeter Evaluation of Limited Ductions
Forced duction testing can be performed in the office with the patient awake or in the operating room prior to the start of surgery.
Laboratory testing is indicated when we believe that the patient’s strabismus is either caused by or complicated by the presence of systemic disease. The onset of an acute cranial nerve palsy, for example, should prompt consideration for evaluation of the patient for diabetes, hypertension, and/or other microvascular disease. Testing for myasthenia gravis should be considered for patients with variable strabismus, especially if associated with ptosis and/or evidence of systemic muscle weakness. The presence of other concurrent neurological signs or symptoms should prompt consideration of neuroimaging and/or neurological evaluation, performed in collaboration with the patient’s primary care physician.