An 80-year-old female presented with a two-month history of binocular horizontal diplopia. Her symptoms started immediately following a motor vehicle accident. She lost consciousness at the time of the accident. Computed tomography of the head and orbits showed no acute intracranial or intraorbital abnormalities. After discharge from an outside hospital, she was seen by a local ophthalmologist and continued to complain of constant horizontal binocular diplopia. She was then referred for evaluation of possible extraocular muscle entrapment.
Past medical history was significant for psoriasis treated with ustekinumab. She denied any history of diabetes or hypertension. Past surgical history included an appendectomy in childhood and a remote history of unspecified knee and elbow surgeries. Her family history was significant for diabetes, hypertension, heart disease and thyroid disease. The patient denied tobacco and illicit drug use; she drank alcohol only socially.
The patient’s vital signs were within normal limits. Ophthalmologic examination demonstrated a visual acuity of 20/80 in the right eye, improving to 20/40 with pinhole, and 20/25 in the left eye with no improvement with pinhole. Pupils were equally round and briskly reactive to light, without relative afferent pupillary defect. Visual fields were full to confrontation bilaterally. Ishihara color plates were brisk and full (8/8) bilaterally. External examination showed deep superior sulci in both upper eyelids with symmetric lid position. Hertel exophthalmometry was symmetric. A right esotropia was present in primary gaze. Extraocular motility measurements revealed an incomitant strabismus (Figure 1). A mild right supraorbital hypesthesia was present and infraorbital nerve function was normal. Intraocular pressure by Goldmann tonometry was
9 mmHg on the right and 12 mmHg on the left.
Anterior segment slit lamp examination was unremarkable bilaterally. Dilated funduscopic examination of the right eye was normal. On the left, one intraretinal hemorrhage was noted nasally.
Forced duction and force generation testing were performed after instillation of viscous lidocaine. Forced duction testing of the right eye was normal. Force generation testing confirmed a paretic right lateral rectus.