Encephalitis
In cases of encephalitis, ocular symptoms may include eye pain and photophobia. Lesions in the brainstem, occipital, or temporal lobes may lead to ptosis, nystagmus, extraocular muscle palsy, and incomplete eyelid closure. Conjunctivitis and corneal hypoesthesia or anesthesia may also occur. Pupillary changes may include dilation or constriction, anisocoria, and reduced or absent pupillary light reflexes. In severe cases, fundoscopic findings may show optic disc hyperemia and edema, dilated retinal veins, significantly narrowed retinal arteries, and retinal edema in the posterior pole. Rare cases may present with optic neuritis, optic atrophy, or cortical blindness.
Meningitis
In meningitis, ocular motor nerve involvement may result in extraocular muscle palsy, conjunctivitis, superficial corneal ulcers, and stromal infiltration of the cornea. Optic neuritis, neuroretinitis, optic atrophy, metastatic endophthalmitis, or panophthalmitis may occasionally be observed. Exposure keratitis may develop in comatose individuals. During respiratory failure, pupillary abnormalities may present, such as early-stage pupillary constriction, variable pupillary size, followed by pupillary dilation with reduced or absent light reflexes.