bubble_chart Overview

Compressive optic neuropathy is caused by direct compression or infiltration from intraorbital or intracranial tumors or metastatic cancers, and can sometimes be misdiagnosed clinically, warranting vigilance.

bubble_chart Etiology

Intraocular conditions include optic nerve gliomas, meningiomas, hemangiomas, lymphangiomas, teratomas, and malignant tumors (carcinoma, lymphoma, fleshy tumor, multiple myeloma). Intracranially, space-occupying lesions in the sellar region are more common, such as pituitary adenomas and craniopharyngiomas. Other meningiomas in the anterior clinoid process, middle sphenoid wing, tuberculum sellae, sphenoid ridge, and olfactory groove are also observed. Internal carotid artery tortuosity, sclerosis, or aneurysms occurring at the terminal branches of the internal carotid artery, anterior cerebral artery, or anterior communicating artery can gradually compress the unilateral optic nerve. Metastatic cancers such as nasopharyngeal carcinoma, lymphoreticular cell sarcoma (Hodgkin's disease), frontal lobe gliomas, astrocytomas, hamartomas, subcutaneous nodule tumors, syphilitic gummas, cryptococcosis, sarcoidosis, and carcinomatous meningitis can also cause such compression. Pituitary apoplexy can lead to sudden unilateral vision loss. Sinus cysts and polyps, especially those in the sphenoid sinus and posterior ethmoid sinus, can be particularly insidious in causing compression. Thyroid disorders causing extraocular muscle hypertrophy, retro-orbital edema, and skeletal deformities can also compress the optic nerve.

bubble_chart Clinical Manifestations

The main clinical features are unilateral progressive and painless insidious vision loss. Vision often presents as a hazy blur, and transient amaurosis may occur immediately when gazing at a certain position, caused by direct compression of the optic nerve or vascular interference. Vision loss is often discovered incidentally. Tumors causing a {|###|}stirred pulse{|###|} may present with eye pain. Early-stage fundus examination may show no changes, and it may take a year or longer to observe pallor of the optic disc, eventually leading to optic nerve pallor, which may appear as a cup-shaped depression. Tumors located near the posterior part of the optic disc may rarely be accompanied by optic disc {|###|}edema{|###|}. Central retinal vein occlusion is rare. Intracranial tumors (particularly olfactory groove meningiomas at the base of the frontal lobe) can compress the ipsilateral optic nerve, leading to optic atrophy. In the late stage [third stage], due to intracranial hypertension, the contralateral eye may exhibit optic disc {|###|}edema{|###|}, clinically known as Foster Kennedy syndrome. Visual field testing is of great significance. Early-stage examinations may reveal a central scotoma, which can quickly expand to the periphery, maintaining peripheral vision for a period before complete vision loss occurs. In some cases, depending on the site of compression, segmental visual field defects may occur as an early feature, expanding inward and eventually affecting central vision. Contralateral superior temporal visual field defects are often mild, resulting from involvement of the nasal fibers of the optic chiasm. Since the inferior nasal fibers loop forward to connect with the anterior part of the {|###|}myopia{|###|} bundle, the presence of an ipsilateral central scotoma is almost diagnostic of compressive optic neuropathy. Rarely, a crossed homonymous hemianopia may occur due to ipsilateral optic tract involvement, and other findings may include paracentral arcuate, vertical nasal, or temporal hemianopia.

Pituitary dysfunction is a common symptom of sellar space-occupying lesions, particularly pituitary adenomas and craniopharyngiomas, manifesting as {|###|}amenorrhea{|###|}, erectile dysfunction, smooth skin, and loss of pubic hair, whereas meningiomas and {|###|}stirred pulse{|###|} tumors may not present with endocrine symptoms.

bubble_chart Diagnosis

It is difficult to diagnose based solely on clinical symptoms and signs, as there is no distinction from optic neuritis or retrobulbar optic neuritis caused by inflammation. Neuroradiological examinations are of great importance for detecting orbital and intracranial space-occupying {|###|} lesions. Plain radiographs of the orbit, skull, or multi-slice sections, as well as imaging of the optic nerve canal, are all quite valuable. The recent advancements in cranial CT and MRI have epoch-making significance, providing definitive diagnoses for intraorbital and intracranial space-occupying {|###|} lesions. For suspected cases caused by {|###|} disease, carotid {|###|} angiography should be performed. There is a misconception that CT scans can diagnose all intracranial pathologies. Small {|###|} tumors with a diameter of 1 cm may yield negative results in all examinations, and follow-up ultrasound exploration may reveal characteristic findings for compressive lesions at the orbital apex. Contrast sensitivity testing holds certain value for compressive optic neuropathy. Sometimes, even when visual acuity remains normal, abnormal changes may be detected earlier than visual field or color vision tests. When other examinations reveal abnormalities, this test may show a general decline across all spatial frequencies. Electrophysiological examinations of vision aid in diagnosis and can provide qualitative insights, though localization remains challenging. They are particularly meaningful for cases with normal visual acuity and optic discs but only blurred vision, especially when comparing both eyes for a clearer diagnosis. In middle-aged individuals, if one eye shows progressive optic atrophy, a short history, and visual field defects progressing vertically, while ruling out glaucoma, vascular disease, or spinal cord tumors, the presence of a {|###|} tumor should be considered. For bilateral vision loss without myelitis, intracranial compressive {|###|} lesions should be suspected. Notably, cases resembling retrobulbar optic neuritis with fluctuating vision should raise suspicion of craniopharyngioma or {|###|} tumor. The former may show temporary improvement after cyst treatment, while the latter may exhibit unstable changes.

In summary, for unexplained unilateral or bilateral progressive vision loss that does not improve or only temporarily improves with treatment, and is clinically diagnosed as optic neuritis, retrobulbar optic neuritis, or optic atrophy, the possibility of intracranial space-occupying {|###|} lesions compressing the optic nerve should be considered.

bubble_chart Treatment Measures

For orbital tumors located in the posterior orbit, surgical removal is generally feasible. For tumors at the junction of the orbit and skull, neurosurgical intervention, particularly a frontal craniotomy, is often combined. This approach offers a wide surgical field, facilitating complete tumor removal and has become widely adopted due to its advantages. Intracranial space-occupying sexually transmitted diseases require neurosurgical treatment, with meningiomas being the most common cause of unilateral optic nerve compression. Early-stage cases can be completely cured through removal. Ophthalmologists are often the first to identify such patients, thus bearing greater responsibility. In more advanced stages [third stage], if the tumor extends to involve the anterior cerebral stirred pulse and internal carotid stirred pulse, complete surgical removal becomes challenging. If intracranial space-occupying sexually transmitted disease is suspected despite negative results from multiple tests, exploratory surgery may be performed. If the optic nerve is not entirely damaged post-surgery, vision can rapidly improve. Pre- and post-operative monitoring can be conducted using electrophysiological methods such as visual evoked potentials. Stirred pulse tumors can be directly occluded and ligated via craniotomy.