Orthoptic Measurements: How do Canadian Ophthalmology Residents Interpret Them in the Context of Cranial Nerve Palsy?

Patients who develop acute problems with ocular misalignment often present urgently to resident-run ophthalmology clinics with complaints of diplopia. Correct diagnosis of the etiology of ocular misalignment is essential to select appropriate subsequent investigations and interventions. Classic neuro-ophthalmic teaching for identifying cranial nerve palsies uses a picture of a patients eye positions in nine fields of gaze to teach the trainee to identify the presence of an eye misalignment and which nerve is involved. In the pictures the deviated eye is evident, the presentation is classical and clear cut and identification of the affected cranial nerve relies on simple pattern recognition. In clinical practice, patients presentation can be less than classical and orthoptic measurements are helpful to make the diagnosis. To use these measurements appropriately, the trainee must have the knowledge required to interpret them. Currently there are few resources commonly available and used by ophthalmology residents.