This Week's Eye-Openers

American Journal of Ophthalmology Case Reports

Pupil-sparing third-nerve palsy: more than meets the eye

While a pupil-sparing third nerve palsy is often thought to indicate an ischemic etiology, it can sometimes be a red flag for infectious causes. A 37-year-old man with HIV and a CD4 count of 61 cells/μL presented with two months of worsening headaches, a seizure three weeks prior, new binocular diplopia, and days of increasing drowsiness. Exam revealed a partial right third nerve palsy, ptosis with limited adduction, elevation, and depression, but with the pupil fully spared and reactive, which originally suggested ischemic microvascular disease over compressive or infiltrative etiologies. However, neuroimaging revealed multiple enhancing intracranial lesions with surrounding vasogenic edema. Cerebrospinal fluid was positive for varicella zoster virus, but stereotactic brain biopsy ultimately confirmed a diagnosis of cerebral toxoplasmosis. The patient improved with combined antimicrobial therapy.

“Pupil-sparing” in the setting of third-nerve palsy often reassures clinicians that the etiology is ischemic rather than compressive. However, this case illustrates the reverse in an immunocompromised patient, in whom opportunistic intracranial infections may selectively affect the nerve's somatic fibers while leaving the superficial pupillomotor fibers untouched, ultimately leading to a pupil-sparing third-nerve palsy. In HIV-positive patients, especially with advanced immunosuppression, a pupil-sparing pattern shouldn't delay an urgent workup for infectious or mass-occupying intracranial disease. Resolving real diagnostic uncertainty may ultimately require a biopsy.

You are a resident seeing patients in a comprehensive clinic. Your next patient is a 68-year-old Caucasian woman who presents after “noticing brown spots when looking at the white of her eye in the mirror.” She first noticed the brown spots about 1 month ago. She feels that they have changed shape and have possibly been getting larger. She denies any family history of similar eye lesions. Likewise, she has no family history of any cancer. Slit lamp exam is notable for 1+ NS in both eyes and pigmented lesions only in the right eye (see image below). The pigmented lesions appear flat and without fluid. The lesions are located on the temporal bulbar conjunctiva with involvement of about 3-4 clock hours at the limbus with minimal extension onto the peripheral cornea. 

What is the best initial approach for management?

A) Observation and reassurance

B) Topical MMC alone

C) Surgical excision with cryotherapy

D) PET-CT

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