Phenytoin toxicity can present with which ocular sign on a dilated examination?

Phenytoin toxicity can present with which ocular sign on a dilated examination?

• A. Retinal hemorrhage
• B. Conjunctival edema
• C. Diplopia
• D. Miosis

Answer: (C)

Phenytoin toxicity commonly disrupts ocular motor control, so extraocular movements can become misaligned and produce diplopia. When you perform a dilated exam and assess motility, you may observe impaired eye movements or a resultant double vision as the eyes fail to align properly due to CNS effects of the drug. This is the ocular sign most consistent with phenytoin toxicity. Retinal hemorrhage and conjunctival edema are not typical manifestations of phenytoin toxicity, and miosis would not be expected in this context. The optic and retinal findings aren’t the hallmark features here; the key clinical clue is diplopia from impaired extraocular muscle coordination.

Phenytoin toxicity commonly disrupts ocular motor control, so extraocular movements can become misaligned and produce diplopia. When you perform a dilated exam and assess motility, you may observe impaired eye movements or a resultant double vision as the eyes fail to align properly due to CNS effects of the drug. This is the ocular sign most consistent with phenytoin toxicity.

Retinal hemorrhage and conjunctival edema are not typical manifestations of phenytoin toxicity, and miosis would not be expected in this context. The optic and retinal findings aren’t the hallmark features here; the key clinical clue is diplopia from impaired extraocular muscle coordination.