Scotoma (Blind Spot) - The Eye Care Advocate

A scotoma is a localised area of partial or complete blindness within an otherwise normal visual field. Depending on its location, it can be entirely harmless or a sign of severe eye disease.

Linguistic Context:
Type: Noun. UK Usage: Spelt “Scotoma.” Plural: “Scotomata.”, however, “Scotomas” is also accepted.

A scotoma represents a specific, localised area of depressed visual sensitivity or total blindness situated within a patient’s visual field.

Every human eye possesses a natural, physiological scotoma, universally known as the blind spot, corresponding to the optic disc where no photoreceptor cells exist.

However, pathological scotomata indicate distinct nerve or retinal damage. A “central scotoma” obliterates the very middle of the patient’s vision and is the devastating hallmark of advanced macular degeneration.

Conversely, an “arcuate scotoma” follows the arching anatomical path of the retinal nerve fibres and is a classic, definitive sign of progressing glaucoma.

Optometrists accurately map the exact size, shape, and depth of these visual field defects using sophisticated, computerised automated perimetry equipment during eye examinations and ophthalmology visits. These are called visual field screeners.

Frequently Asked Questions About Scotoma

What is a scotoma and does it mean I’m going blind?

A scotoma is simply a localised area of reduced or missing vision—essentially a “blind spot” in an otherwise normal field of view. While the word sounds serious, it doesn’t always mean you are going blind.

Some scotomata are permanent (like our natural blind spot), while others can be temporary, such as the shimmering “aura” some people experience before a migraine.

However, if you notice a new, fixed dark spot in your vision, you should have it checked urgently by an optometrist.

Why do we all have a natural blind spot in each eye?

Every human has a natural, physiological blind spot located about 15 degrees to the outside of their central vision. This exists because of how the eye is “wired.” All the nerve fibres from your retina bundle together to exit the eye and travel to the brain.

At this specific exit point (the optic disc), there is no room for light-sensitive cells. Because there is no retina there, that tiny spot is completely blind.

How can I find my own blind spot at home?

To find your natural blindspot, follow these simple steps.

You will need a piece of paper and a pen. Draw a cross on the centre of the piece of paper, then a dot 4 cm immediately to the right of it.

Close your left eye and stare at the cross with your right eye. Whilst looking at the cross, bring the paper towards your eyes. At about 14-10 cm away from your eye, you may notice the dor disappear. This is where your normal blind spot is in this eye.

Is it true that we have a massive “scotoma” behind our heads?

Technically, yes! While we don’t usually call it a “scotoma” in a clinical setting, we are all effectively “blind” to the world behind us. Because our eyes are positioned on the front of our faces and our retina only lines the back of the eye, our horizontal field of view is limited to about 200 degrees. Everything behind that (roughly 160 degrees of the world) is a massive gap where no visual information is captured. We only “see” behind us by turning our heads or using mirrors.

What is the difference between a positive and a negative scotoma

A positive scotoma is one that the patient “sees”—it appears as a dark spot, a shadow, or a blur in their vision (common in macular degeneration).

A negative scotoma is one the patient is unaware of; the brain simply “fills in” the gap with surrounding information. These are usually detected during a visual field test (perimetry) and are common in the early stages of glaucoma.

Medical Disclaimer: This glossary entry is intended for informational and educational purposes only. It does not constitute medical advice, diagnosis, or treatment. If you are experiencing changes in your vision or ocular discomfort, please consult a qualified optometrist or your primary care provider immediately.

UK Authority Resources & Clinical Guidelines:
NHS England | NICE Guidelines | The College of Optometrists | Association of Optometrists (AOP) | General Optical Council (GOC)