bubble_chart Overview

Retrobulbar neuritis is generally classified into acute and chronic types, with the latter being more common. Depending on the part of the optic nerve that is affected, retrobulbar neuritis can be divided into several different types: the lesion most commonly affects the fibers of the optic disc macular bundle, which is located in the central part of the retrobulbar orbital segment of the optic nerve, hence it is also known as axial neuritis; when the lesion invades the peripheral fiber bundles of the optic nerve from the nerve sheath membrane, it is called perineural stromal neuritis, which is only a pathological change and is difficult to diagnose clinically; if the entire transverse section of the optic nerve fibers is affected, there is no light perception and it appears as amaurosis, known as transverse optic neuritis.

bubble_chart Etiology

The aforementioned causes of neuritis can all serve as pathogenic factors for this disease. Acute cases are often caused by nearby inflammatory lesions, such as sinusitis, particularly inflammation or cysts in the posterior ethmoid and sphenoid sinuses, which are more prone to misdiagnosis. Poisoning from lead, arsenic, methanol, ethanol, as well as orbital cellulitis and basal meningitis can also lead to the condition. Chronic cases are frequently due to vitamin B deficiency, pregnancy and lactation, diabetes, demyelinating diseases (multiple sclerosis is not rare in China, though significantly less common than in the West. Optic neuromyelitis is now mostly considered a variant of multiple sclerosis), and familial optic atrophy (Leber's disease), with idiopathic cases still accounting for about half.

bubble_chart Clinical Manifestations

The condition often affects one eye but can also involve both eyes, typically presenting with a rapid decline in vision, even to the point of no light perception. The pupil is moderately dilated, with a sluggish or absent direct light reflex. There may be traction pain or deep orbital pain during eye movement. In the early stages, the fundus appears normal, but in advanced stages, there may be varying degrees of pallor on the temporal side of the optic disc. Visual field defects include central, paracentral, and dumbbell-shaped scotomas, as well as peripheral visual field constriction. It is crucial to emphasize the examination of the central visual field rather than the peripheral field, and to use red targets with as small a stimulus as possible. Transient blurring of vision during exercise or hot baths, with improvement in vision at cooler temperatures or after consuming cold drinks, is known as Uhthoff's sign. This phenomenon is commonly seen in optic neuritis caused by multiple sclerosis and Leber's disease, but can also occur in other forms of optic neuritis. It is hypothesized that this sign is related to the direct interference of increased body temperature with axonal conduction and the release of chemical substances.

bubble_chart Diagnosis

Based on visual acuity and fundus examination, especially visual field testing, typical cases are easily diagnosed. Tests such as color vision contrast sensitivity and VEP also have certain auxiliary diagnostic significance. The presence of abnormal cells in the cerebrospinal fluid, elevated gamma globulin, and increased viral antibody titers may suggest multiple sclerosis. Monoclonal antibodies in the cerebrospinal fluid can be elevated in 90% of cases, but non-specific HLA-A₃

and B₇ are also helpful in diagnosis.

bubble_chart Treatment Measures

Optic neuritis. For severe cases that do not respond to hormone therapy, a maxillary sinus approach can be used to open the ethmoid and sphenoid sinuses. Under a surgical microscope, the inferior wall of the optic canal is removed to decompress the optic nerve, improve nerve nutrition, and facilitate the recovery of optic nerve function. Generally, good results can be achieved in the acute phase, but severe cases may lead to temporal optic nerve atrophy or even complete atrophy and blindness. The chronic phase progresses slowly and is often bilateral. It is frequently caused by delayed treatment or prolonged disease course, leading to significant temporal optic nerve atrophy, with a poorer prognosis.

bubble_chart Differentiation

This disease should be differentiated from the following conditions:

1. Refractive errors, especially farsightedness and astigmatism, may cause eye pain, headache, and blurred vision. The optic disc changes resemble those of optic neuritis, making misdiagnosis highly likely. Refraction and retinoscopy can confirm the diagnosis, and wearing corrective lenses can alleviate the symptoms.

2. Corneal nebula or posterior capsule grade I confusion, often due to clinical oversight, can be diagnosed through slit-lamp examination.

3. Hysterical amaurosis, with no change in the pupils and episodic characteristics. Visual field examination shows a spiral-like constriction. There is a clear history of predisposing factors. It can be treated with suggestive therapy.

4. Malingering, although the patient complains of significant visual impairment, long-term objective examinations show no positive findings. Various malingering tests can aid in differentiation, and a normal VEP can immediately rule it out.

5. Intracranial tumors, especially those in the sellar region, may present with changes similar to retrobulbar optic neuritis in the early stages. Visual field and skull X-rays can aid in diagnosis, and cranial CT and MRI are more helpful for early detection.