Normally, the eyes move together in concert: when the left eye moves left, the right eye moves left, too. The brain takes the input from each eye and puts it together to form a single image. This coordinated movement depends on 6 extraocular muscles that insert around the eyeballs, allowing the eyeballs to move in all directions. Each muscle is innervated by one of 3 cranial nerves (CN): CN III-Oculomotor, CN IV-Trochlear and CN VI-Abducens.
During the physical exam, the patient is asked to track a pen or the provider’s finger to evaluate the movements of the eye in all the directions of gaze. Any restrictions or weakness in eye movements may be due to nerve palsies, myopathies, or even fractures of the orbital bones.
In the majority of cases, a remark regarding extraocular movements, such as extraocular movements normal or extraocular movements intact (EOMI) can be construed to be a test of the cranial nerves, and thus, a neurological exam finding. However, be aware that in some other cases, especially in cases of injury or muscular disorders, this exam finding might be more appropriately qualified as a finding for the Eye organ system under the 1995 E/M Documentation Guidelines. Appropriate application of this exam finding will be dependent upon the nature of the patient’s presenting problem.