Eye Alignment Examination

    • Assessment of the alignment of the eyes
    • Step 1: assess the amplitude of horizontal and vertical pursuit and saccadic movements, which might give you a clue to any ocular misalignment (See Eye Movements Examination )
    • Tip: remember that even if the amplitude of eye movements is normal, you must measure alignment because it may be abnormal
    • Step 2: measure alignment with the Cover Test
    • Tip: the Cover Test will fail to detect an ocular misalignment if patients are unable to make fixational movements because of poor vision or severely impaired eye movements; even if they are able to make those fixational movements, they may not do so unless advised that they must try to “make the target appear distinct”
    • Step 3: if the patient reports diplopia, use the Single Maddox Rod Test in addition to the Cover Test (or instead of the Cover Test) to measure alignment
    • Tip: the Single Maddox Rod Test will fail if the patient is unable to see the red line with one eye and the white fixation light with the other eye
    • Step 4: if the patient is reporting vertical diplopia, use the Double Maddox Rod Test to assess torsional alignment
    • Step 5: if the patient cannot cooperate with the Cover Test or the Maddox Rod Test, estimate eye alignment crudely by observing the corneal light reflections
    • Comitant eye misalignment means that the degree of misalignment does not vary with gaze position
    • Incomitant eye misalignment means that the degree of misalignment varies with gaze position
    • Comitant eye misalignment with diplopia: this is caused by a breakdown of the brain’s ability to maintain ocular alignment (“fusional force”) because of one of the following conditions
      • Poor vision in one or both eyes
      • Foveal distortion, creating dissimilar images as seen by each eye
      • Brainstem lesion
      • High intracranial pressure
      • Sleepiness
      • Meningoencephalitis
      • Aging
      • Convergence weakness
    • Incomitant eye misalignment with diplopia: this is caused by one of the following conditions
      • Extraocular myopathy
      • Neuromuscular transmission failure
      • Ocular motor cranial nerve palsy
      • Internuclear ophthalmoplegia
      • Skew deviation
    • Comitant or incomitant misalignment without diplopia: this is caused by one of the following conditions
      • Misalignment present at birth or in early childhood, so that the image viewed by the deviating eye has been suppressed
      • Patients have such poor vision in at least one eye that they will not have diplopia despite eye misalignment
      • Patients do not appreciate diplopia because the images are minimally or very widely separated
      • Patients cannot express diplopia because they have a language or cognitive deficiency
      • Tip: even very alert patients may report diplopia as “blurred (indistinct) vision”

    Additional Examination Techniques

    Visual Acuity Examination Color Vision Examination Pupil Examination Eye Movement Examination Eye Alignment Examination