![image.png](https://images.hive.blog/DQmZeq6jWwPdxenGrFoWMp5wQhENFizLt281nnWgT9ej89z/image.png)
[Source](https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.wired.com/2015/02/5-things-every-human-know-light/&ved=2ahUKEwj9pY6M4sj5AhXmQfEDHe3sCNYQ8g16BAgWEAA&usg=AOvVaw3kYUq8ooZztJWedELA08Yi)


I wondered for a long while that what was the science behind me not seeing in dark, it was so funny but I being an inquisitive person wondered so much about it and I had to read about it.

**The Eye as an organ of sight**

An organ is a group of similar **tissues** forming a layer in an organism 
which is specialized to perform a function in an organism. 
> A **tissue** is made up of similar cells which is specialized to perform a function. In other words, tissues are similar cells that work together to perform a role in an organism. 


![image.png](https://images.hive.blog/DQmPCAYT5WJSeXsdYkS6ZyWhFHgTiqk8ETYFmtqsNnN2HiJ/image.png)
[Source](https://www.google.com/url?sa=t&source=web&rct=j&url=https://my.clevelandclinic.org/health/body/21823-eyes&ved=2ahUKEwiziuv34sj5AhVTYPEDHUr0CCAQFnoECA4QAQ&usg=AOvVaw0csr5YJgrC9D4wlMRibo67)

The parts of the eye are all made up of cells and most of these cells in the eye are sensitive to light. The cells of the eye become inactive when there is no light stimulus and this makes us conclude that light acts as an essential element in sight.

**Processes By Which Light Helps in Vision**

The labelled parts of the eyes in the image above helps in sight and they all give a response whenever they receive light stimulus. 

>Living things(cells) are characterized to be sensitive

*Parts of the eyes from anterior(front) to the posterior(back) view as labelled in the vertical section of the eye*

>Conjunctiva 
Cornea
Aqueous humour
Sclera(white eye)
Iris 
Pupil
Lens
Ciliary muscle
Vitreous humour
Retina - yellow spot
Blind spot 
Optic nerve

Back to our subtitle, lets look at the processes by which light helps in sight. When light touches a thing, it gives a reflection of that thing 

 
![image.png](https://images.hive.blog/DQmaJcXCpnmj6xu8PUjoiAWmzM37WzW7pP2TKJm4jRBAbyp/image.png)
[Source](https://leverageedu.com/blog/reflection-of-light/)



I would use the image above to explain what I stated above. The girl looking at the mirror could only see her image on the mirror because of the effect of light in the environment, if the environment was dark, she wouldn't have seen her image. This explains why one can't see in dark, light gives the **retina** the ability to form an image of the object which has been seen. Either dim light or bright light has the ability to form an image but the difference in their image clarity will be seen.

For an object to be seen, Light enters 
 firstly enters the **pupil** and the **iris** controls the amount of light entering **pupil**. The **conjunctiva, cornea, aqueous humour , lens ,vitreous humour and the retina** allow light to pass through them in order for **REFRACTION** of the light rays to take place. The refraction of the light rays causes convergence of the light rays on the retina.

> Refraction is the bending of light rays as a result of the change of speed of light when it travels from one medium to another

When the light rays convergences at the retina, an image is formed. Now the image formed on the **retina** is inverted and smaller than the object but there is a solution to this which is - the optic nerve sends information to the brain that the eye just received this kind of stimuli from light, then the brain interprets this information correctly, that is, the size and orientation of the image correctly. The brain makes us know the exact size of the object and also orientates us of the object correctly.
For a sharp image of the object to be formed, all the light rays reflected from a particular point on the object must meet again exactly at the retina(**yellow spot**)


*Therefore, we can say that without light there is no sight because an image as to be formed on the retina for an object to be seen*