Cerebral Artery Occlusion
Cerebral artery occlusion presents with varying ocular manifestations depending on the affected site. Occlusion of the common carotid artery or internal carotid artery may result in transient monocular visual loss (amaurosis fugax) or permanent vision loss in the affected eye. Homonymous hemianopia on the side opposite the lesion may occur in both eyes, or there may be total blindness in the ipsilateral eye combined with temporal hemianopia in the contralateral eye. Ischemic optic neuropathy may also occur on the affected side. Fundoscopic findings may vary, showing no significant changes or presenting with mildly pale optic discs and retina alongside narrowing of retinal arteries.
Middle cerebral artery occlusion often manifests as contralateral homonymous hemianopia without macular sparing, and it may also present as lower nasal quadrant hemianopia. Posterior cerebral artery occlusion leads to contralateral homonymous hemianopia with macular sparing, cortical blindness, or quadrantanopia. Basilar artery occlusion is associated with pupil constriction and cranial nerve paralysis involving cranial nerves III (oculomotor), IV (trochlear), and VI (abducens).
Intracranial Aneurysms
Intracranial aneurysms are a primary cause of spontaneous subarachnoid hemorrhage and can occur in any location within the intracranial arteries, with a predilection for the bifurcation of the internal carotid artery and posterior communicating artery. Symptoms often include periorbital and frontal pain, diplopia, reduced vision, and proptosis. Additional ocular findings may include eyelid congestion and swelling, lower eyelid eversion, conjunctival edema, engorged and tortuous scleral veins, and subconjunctival hemorrhages. Pupils may be unequal bilaterally. Fundoscopic changes may reveal optic disc edema, dilated and tortuous retinal veins, and retinal hemorrhages. Chronic cases may show ipsilateral optic atrophy and pulsating of the eyeball.
Ocular motility disturbances may occur due to cranial nerve impairment. If an aneurysm compresses the lateral part of the optic chiasm or the junction of the optic chiasm and optic nerve, nasal scotomas or defects in the ipsilateral eye may occur, along with superior temporal visual field defects in the contralateral eye. When an aneurysm compresses one side of the optic chiasm, causing displacement toward the contralateral side, bitemporal hemianopia may arise.
Intracranial Hemorrhage
Subarachnoid Hemorrhage
Subarachnoid hemorrhage may involve cranial nerve paralysis, retinal arteriolar narrowing or segmental constriction, engorgement and dilation of retinal veins, and retinal or preretinal hemorrhages. Severe cases may present with optic disc edema.
Intracerebral Hemorrhage
Intracerebral hemorrhage most commonly occurs in the basal ganglia region (approximately 80% of cases).
- Putaminal or External Capsule Hemorrhage: Presents with unequal pupils, homonymous hemianopia on the side opposite the lesion, and optic disc edema.
- Thalamic Hemorrhage: Presents with small, unequal pupils, loss of the pupillary light reflex, impaired vertical eye movements, and downward or nasal downward gaze in both eyes. If the hemorrhage extends into the third ventricle, gaze deviation toward the paralyzed side, optic disc edema, and, less commonly, hemianopia may occur.
- Ventricular Hemorrhage: Presents with unequal pupils, sluggish or absent pupillary light reflex, conjugate gaze paralysis, and optic disc edema.
- Brainstem Hemorrhage: Presents with small, bilaterally constricted pupils and reduced or absent pupillary light reflexes. In severe cases, there may be dilated or unequal pupils, central gaze fixation of both eyes, and cranial nerve paralysis involving cranial nerves V (trigeminal), VI (abducens), VII (facial), and VIII (vestibulocochlear). Gaze deviation toward the lesion side or ocular bobbing and unilateral or bilateral ptosis may be present.
Venous Sinus Thrombosis
Cavernous Sinus Thrombosis
Cavernous sinus thrombosis often includes visual impairment, orbital pain, eyelid swelling, conjunctival congestion and edema, engorgement, and tortuosity of conjunctival and scleral veins. Additional features may include proptosis, optic disc edema, dilated retinal veins, and retinal hemorrhages. Cranial nerve paralysis may also be present.
Superior Sagittal Sinus Thrombosis
Superior sagittal sinus thrombosis may manifest with visual impairment, transient vision loss, or diplopia. Unilateral or bilateral abducens nerve palsy may also occur, along with hemianopia, optic disc edema, and retinal hemorrhages.