Causes and risk factors
Bjerrum scotoma is caused as a result of damage to the arcuate temporal nerve fiber bundles located in the eye. The nerve fiber bundle defect occurs most commonly in the ‘Bjerrum area’ of the field of vision. The Bjerrum area is present superior and inferior to the blind spot to between 10 and 20 degrees of fixation point.
Glaucoma is the commonest underlying cause for the development of a Bjerrum scotoma. Other causes include optic nerve drusen, choroiditis, coloboma, retrobulbar neuritis, meningioma, arterial emboli, papilledema, and pituitary adenoma.
Clinical presentation
While looking at any object, the patient will notice a blurred or black spot in a fixed elliptical area of vision. The area adjacent to the blind spot will appear normal.
Investigations
Scotoma can be diagnosed on the basis of Visual Field Testing. In this test, mapping of the visual field of each eye is done. The patient is advised to look at a screen and press a button whenever he sees a light with his peripheral vision. This test helps to detect the location and dimensions of a scotoma.
The ‘Bjerrum tangent screen test’ is used to measure the central 30 degrees of the visual field.
Other investigations may be suggested in order to detect the cause of the scotoma. This includes ophthalmoscopic examination, imaging scans of the brain, necessary laboratory tests, and sometimes even an angiography.
Treatment
Treatment involves identifying and treating the underlying cause of scotoma. However, the scope for improvement of scotoma is very limited.
When to contact a doctor
Contact a doctor as soon as you experience any visual loss or blurring.
Systems involved
Ophthalmology, nervous.
Organs involved
Eyes, brain.
