Where does a blind spot in the retina occur?

Answer 1

Most commonly, blind spots in the retina are on or nearby the pupil/iris. It should be looking "clouded" and they might even get a blue tint to them.

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The above answer makes very little sense at all but I'll leave it in for now just in case it is somehow what was wanted. It'd be fairer to let an objective adjudicator decide.

Anyhow....a blindspot on the retina occurs at the optic nerve. This is because as light enters the eye (through the pupil) it is projected onto the retina, which is essentially the back wall of the eye.

Your retina is covered in tiny little sensors known as rods and cones (generally speaking cones allow colour vision during the day and rods allow the grainy black and white sight in the dark). So when light hits these cells, it breaks down pigments inside the cell according to wavelength (thus colour!) and that sends signal from that cell to the brain.

There are millions of these in each eye and when you add them all up, you get a complete picture of that which is projected upon the back of your eye.

However! All of these cells must have nerves running from them to the brain so these signals can be sent. All of these nerves from the retina are bundled together, where they meet at a certain point in the retina and then lead out the back of the eye into the brain. This bundle is called the optic nerve and obviously at that point on the retina, there's no rods or cones...meaning no light at that point is actually collected or processed, giving you a blind spot.

To demonstrate this, you can do a classic blind spot test. You can do it with paper and a pencil, or there's a web version here:

http://www.blindspottest.com/

Answer 2

The 'blind spot' is the area where the eye connects to the optic nerve. There are no light sensitive cells here.