Definition

Retrobulbar or retro-orbital tumors are tumors located behind the eyeball within the retro-orbital space. This space comprises eye muscles, nerves, blood vessels, and soft tissues. Retrobulbar tumors cause an increase in orbital cavity volume, exerting pressure on surrounding eye structures. These tumors can extend to affect the optic nerve, brain, or even bone marrow via blood vessels.

Clinically, the growth of retrobulbar tumors not only enlarges the volume of orbital cavity but also induces inflammation, affects the immune system, and enlarges adjacent normal cells. Expansion of tumor cells in the retrobulbar region may lead to outward protrusion of the eye (proptosis) and inward pressure on the optic nerve.

Causes

There are various types of retrobulbar tumors, including:

• Cavernous Hemangioma

A cavernous hemangioma is a benign tumor that can develop within the orbital cavity, typically located behind the eyeball, leading to proptosis as it pushes the eye forward.

This benign tumor grows slowly and causes gradual proptosis without any pain. They are usually unilateral, affecting one eye asymmetrically, while bilateral cases (tumors in both eyes) are uncommon.

• Glioma

Optic nerve gliomas are a type of brain tumor originating in glial cells and primarily affecting the optic nerve. These gliomas typically grow slower than other brain tumors and are often found at the chiasm, a place where the left and right optic nerves intersect.

Optic nerve gliomas are rare, usually occurring in children, and are seldom seen in individuals over 20 years old. Malignant forms, such as glioblastomas, are less common, predominantly affecting adult men. Glioblastomas have poor prognosis, often resulting in death within a year. Optic nerve gliomas constitute about 1% of all brain tumors.

• Meningioma

Meningiomas arise from arachnoid cells in the meninges, the layers covering the brain. This tumor can appear in the orbital cavity either as primary orbital meningiomas (originating from the optic nerve sheath) or secondary orbital meningiomas (spreading from the brain into the orbital cavity). These tumors generally grow slowly and are benign.

• Rhabdomyosarcoma

Orbital rhabdomyosarcoma (RMS) is the most prevalent primary orbital cancer in children, with approximately 35 new cases annually. RMS is commonly found in the head, neck, and orbital regions. It is a malignant tumor that, if diagnosed early, can significantly improve patient outcomes.

RMS mainly affects children, with 90% of cases occurring before age 16 and typically between ages 5 and 7. The male-to-female ratio for this cancer is 5:3, with no known racial predisposition.

RMS comprises striated muscle cells at various developmental stages and can manifest in several body parts, including the orbital area. Most orbital RMS cases originate in the orbital soft tissue rather than the extraocular muscles. RMS can also be secondary, spreading from other body regions to the orbital cavity, particularly developing in orbital soft tissues.

Risk Factor

Most retrobulbar tumors are hereditary. Therefore, individuals with a family history of eye tumors are at increased risk. In cavernous hemangiomas, no specific risk factors have been identified, although pregnancy is associated with accelerated tumor growth.

Increased risks of meningiomas are linked to a history of radiation therapy, neurofibromatosis type 2, and certain gene mutations. Rhabdomyosarcoma, on the other hand, typically arises spontaneously but can be associated with conditions such as neurofibromatosis, Li-Fraumeni syndrome, and developmental abnormalities like Beckwith-Wiedemann syndrome.

Symptoms

Proptosis, or exophthalmos, is the protrusion of the eyeball. This is a common symptom of retrobulbar tumors or cancer. It occurs due to an increase in volume in the eye socket, forcing the eyeball outward.

• Cavernous Hemangioma

Orbital cavernous hemangiomas are more commonly seen in middle-aged women. Typically found in the muscle conus (eye muscles with cone shape), but can also occur in other parts of the orbit. This tumor pressed on the optic nerve and can cause damage.

Outward eyeball protrusions caused by tumors will cause the outer layer of the eyes to lack protections from eyelids and the surrounding tissues. Symptoms include proptosis, dry eyes, irritation, increased risks of injury, double vision, visual field disturbances, impaired visual acuity, and impaired pupil and eye muscle function. Proptosis caused by cavernous hemangiomas is usually painless and progresses slowly.

• Glioma

Symptoms result from glioma pressure on the optic nerve and may include:

• • Nausea and vomiting
  • Balance problems
  • Gradual and painless proptosis
  • Visual impairment
  • Headache
  • Involuntary eye movements
  • Memory impairment
  • Daytime sleepiness
  • Loss of appetite
  • Growth retardation
  • Hormonal issues due to tumor close proximity to brain areas that regulate hormone
  • Gradual loss of vision

• Rhabdomyosarcoma

Symptoms generally include:

• • Proptosis (80-100%) on one side of the eye, progressing rapidly over weeks
  • Eyeball displacement (80%)
  • Swelling of the conjunctiva and eyelids (60%)
  • Palpable lump (25%)
  • Ptosis or drooping of the eyelids (25%)
  • Pain and minimal vision loss in advanced stages

Diagnosis

• Cavernous Hemangioma

This type of tumor typically grows slowly and can be observed before taking treatments into consideration if no eye damage is present. Ultrasound and CT scans can help detect oval or round mass with clear borders. Doppler examination shows slow blood flow within the tumor.

Tissue examination reveals enlarged, tightly connected blood vessels with diameters of up to 1 mm, lined with a single layer of cells.

• Glioma

Neurological examination may show partial or complete vision loss or optic nerve changes. Other considered diagnostic tests are CT scans, MRI of the brain, and nerve biopsies. These procedures assist in diagnosing optic nerve gliomas. MRI often reveals optic nerve enlargement and bending, also useful for detecting brain metastasis (spread of tumors to the brain).

• Meningioma

Symptoms in meningiomas include gradual and painless vision loss, proptosis, double vision, headaches, and pain behind the eyes. Eye examination may reveal a pale and swollen optic nerve, decreased visual acuity, visual field disturbances, eyeball displacement, and limited eye movement. CT and MRI scans are used for further examination.

• Rhabdomyosarcoma

Symptoms of rhabdomyosarcoma include proptosis, eyeball displacement, eyelid protrusion, swelling, redness, and a palpable lump. Initially, the tumor does not affect the bone, but larger tumors can erode bone and spread to the nasopharynx or sinuses. CT scans can show bleeding or tissue death.

Nerve biopsy supports the diagnosis. Excisional or incisional biopsy can be chosen based on tumor location and size. Excisional biopsy is chosen if tumor removal can be done without damaging vital eye structures (eye nerves and muscles), while incisional biopsy is selected for large tumors located at the back of the eye socket to avoid damaging vital structures.

Management

Treatment options for retrobulbar cancer include various methods. Some surgical procedures that can be recommended include:

• Orbitotomy: Tumor removal by opening the orbital tissue.
• Enucleation: Complete removal of the eyeball.
• Orbital exenteration: Partial or complete removal of orbital tissue.
• Endonasal endoscopic surgery: Surgical procedure using a small camera inserted through the nostrils.

Chemotherapy is another treatment option for retrobulbar eye cancer, typically administered intravenously over three to six cycles.

Complications

Nasal polyps can lead to complications by obstructing airflow and hindering sinus fluid drainage. Long-term irritation and inflammation associated with nasal polyps can also contribute to these complications:

• Obstructive sleep apnea. A potentially serious condition where breathing stops temporarily during sleep.
• Asthma attacks. Chronic sinusitis and nasal polyps can exacerbate asthma symptoms.
• Sinus infections. Nasal polyps increase susceptibility to frequent sinus infections.

Prevention

There is no definite way to prevent tumors or eye cancer, including retrobulbar tumors. However, sun rays are believed to be associated with the risk of cancer. You can limit sun exposure to the eyes by wearing a hat or sunglasses with ultraviolet (UV) light protection. In addition, limit exposure to harmful chemicals, especially during pregnancy, to prevent gene mutations caused by chemicals.

When to See a Doctor?

Seek immediate medical attention if you experience signs and symptoms of retrobulbar tumors, particularly proptosis, especially if no other cause is found.

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