What is the structure of an eye? – I'm a Scientist 2024

Question: What is the structure of an eye?
- Keywords:
  eye,
  structure
Asked by Emmanuel to Zoe V, Philippa H, Michael S, Hradini K on 7 Feb 2024. This question was also asked by Lorena.
- Michael Schubert answered on 7 Feb 2024:
  
  Human eyes are quite complicated, but they have a few basic parts. From front to back, it looks a little like this:
  
  – a cornea, which covers the front of your eye for protection and to help bend light so you can see properly
  – a bit behind the cornea, but in front of the pupil and iris, called the “anterior cavity,” which makes and contains a liquid that helps give the eye its shape and also bends light
  – a pupil, which is a hole to let in the light
  – an iris, which has muscles that control the size of the pupil and how much light it lets in (this is also the part of your eye that gives it its colour)
  – a lens behind the pupil that also bends light and is attached to muscles that help change its shape so you can adjust your vision to see things at different distances
  – a bit behind all that called the “posterior cavity,” which contains a jelly-like substance that helps give the eye its shape and focus light
  – a retina, which is a layer (made up of lots of other layers with different types of cells in them) at the back of your eye that detects and processes light into a signal that your brain can interpret
  – an optic nerve to carry that signal from your eye to your brain
  
  Of course, there’s a lot more to it than that. For instance, your eye has blood vessels to bring nutrients to all of those parts, immune cells to help protect it against invaders, and different types of protective layers and muscles and connective tissue that hold everything in place. Eyes are surprisingly complicated organs!
  
  Here’s a diagram to look at:
- Philippa Harding answered on 20 May 2024:
  
  As Michael as said so well, the eye is made up of lots of parts.
  
  I work on the retina, which is at the back of the eye. When light goes through your pupil it hits the retina, and this is the part of the eye which allows us to see.
  
  The retina has layers of different types of cells, which turn the light into an electric signal which can be sent to the brain.
  
  The most important cell type in the retina is the photoreceptors, as they are the cell which can detect light and turn it into an electric signal. People have 2 main types of photoreceptors, rods and cones. Rods look like a stick, and they are important for peripheral vision and seeing at night. Cones are pointy, like an ice cream cone, and they allow us to see colour and details.
  
  Humans have 3 types of cone cell, so we can see blue, green and red light. Some people who are colour blind are missing one of those types of cone, so they don’t see all colours. Some animals also only have 2 types of cone, like dogs, while other animals have 4 or more different types of cone which allows them to see colours we can’t see, like bees which can see UV light!