Optic Disc Drusen - Symptoms, Causes, Diagnosis, and Treatment

Introduction

The optic disc is the connection between the brain and the eye. The image recorded in the eye is transmitted to the brain through nerve impulses through the optic disc. Optic disc drusen are disc swelling secondary to the benign optic process. This optic disc swelling occurs due to the calcification of mucopolysaccharides and mucoproteins around the disc. These calcifications can also be remnants of the axonal transport of retinal ganglion cells.

Optic disc drusen may also be known as pseudo papilledema of optic nerve head drusen. Unlike papilledema, this condition generally has no symptoms. Patients very rarely present with visual symptoms. This condition can occur in one or both of the eyes.

What Is the Occurrence of Optic Disc Drusen?

Optic disc drusen are known to occur in two to five percent of the population, but symptoms can only be seen in 0.35 percent of the affected cases. Hence, this condition is asymptomatic in most cases. However, it is seen to be associated with progressive vision loss. This condition is not associated with any particular race or sex. It can occur at any age, but its progression can be seen.

What Are the Symptoms of Optic Disc Drusen?

Optic disc drusen are mostly asymptomatic but rarely may present with visual symptoms such as:

1. Loss of Visual Field: Loss of the visual field can occur if other pupil defects accompany this defect. However, optic disc drusen can remain asymptomatic.

2. Transient Visual Disturbance: Few patients suffering from optic disc drusen may experience transient visual flickering. This flickering may feel like “blacking out” or “graying out.” These symptoms may also be seen in patients with papilledema.

3. Visual Acuity: Visual acuity is the ability of the eye to distinguish shapes and letters at a distance. Visual acuity may gradually reduce in conditions like optic disc drusen.

What Causes Optic Disc Drusen?

Optic disc drusen can be caused by various factors such as:

1. A Different Course of the Optic Nerve: The optic nerve may enter the optic cavity at an angle higher than usual. This can give an elevated appearance to the optic nerve hence giving rise to optic disc drusen.

2. A Mismatch Between the Eye and the Optic Disc: The eye can be bigger when compared to the optic disc, or the optic disc can be smaller when compared to the eye. This size parity can cause the axons to look crowded, giving rise to optic disc drusen.

3. Partial Myelination of the Nerve Fiber: Partial myelination of the nerve fiber can give an appearance of a bigger optic disc with blurred margins. This can give an appearance of pseudo papilledema.

4. Buried Disc: Calcification of the optic disc can occur with polysaccharides and other proteinaceous materials that are otherwise normal components of the optic disc. This calcification occurs with age. This can develop into a tumor that can make the disc look elevated. As this progresses, it can cause a loss of visual field and visual acuity.

5. Remnants of Congenital Hyaloid: Optic disc drusen can be formed due to remnants of congenital hyaloid. However, this is a very rare occurrence.

6. Tumor of the Optic Disc: Optic disc drusen can be caused due to any tumor of the optic disc. This tumor can be primary or metastatic. But this type of pseudo papilledema may also be associated with other symptoms.

7. Inflammatory Conditions: Optic disc drusen can be caused due to any inflammatory condition of the body, such as syphilis (sexually transmitted), Lyme disease (it is a tick-borne infection), or cat-scratch disease (an infection caused by the saliva of the cat).

How to Diagnose Optic Disc Drusen?

Optical disk drusen are generally asymptomatic and may be diagnosed during a routine eye examination. A doctor may suggest various tests to study the extent of the progression of the disease. Some of the tests that can be done are:

1. Physical Examination: The doctor may examine the eyes using an ophthalmoscope to check for abnormalities. The eyes may be dilated to view the optic nerve.

2. CT (Computed Tomography) Scan: A CT scan can be done to see the area of calcification.

3. Fluorescein Angiography: A dye can be injected into the eye to study its components. This test aids in the visualization of dilated vessels.

4. Visual Field Test: A regular check-up of the eye is necessary in the case of optical disc drusen. In this condition, there is a gradual progressive loss of vision. Hence periodic check-up of the visual field is necessary. This aids in the early diagnosis of visual field loss and loss of visual acuity.

What Is the Treatment for Optical Disc Drusen?

There is no specific treatment for optic disc drusen as it is considered a normal physiological variant. If any other conditions are associated with it, it may require treatment. If this condition progresses to loss of visual field, it may require treatment. Some doctors may suggest eye drops to relieve the pressure on the eyes. The exact cause of the condition has to be found out for appropriate treatment to be given. Hence periodic management of the condition is necessary.

Conclusion:

Optical disc drusen is a progressive disorder of the optic disc that may be asymptomatic for a long time before it starts showing symptoms. If left untreated, it may even progress to losing the visual field. Hence periodic check-up of the eye is necessary to have optimal health.