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Understanding Your Eyes Toolkit

Discover how your eyes work and why protecting vision matters

The human eye is a complex and remarkable organ that allows us to experience and understand the world around us. Vision depends on many different structures working together – from the cornea and lens that focus light to the retina and optic nerve that send information to the brain.

Understanding how our eyes function is an important first step in understanding retinal health.

Understanding Retina Conditions
Our Eyes

A Window Into the World

Vision is created through a complex interaction between the eye, the optic nerve, and the brain. When light enters the eye, it travels through several structures before being converted into signals that the brain interprets as images.
Parts of the Eye
Cornea

The cornea is the transparent outer layer at the front of the eye.

It helps:

  • Protect the eye
  • Focus incoming light
Pupil

The pupil is the dark hole in the centre of the eye that lets light in and  depending on whether this is bright or dim light, the pupil widen or narrow respectively.

Iris

The iris is the coloured part of our eye and is responsible for adjusting the size of the pupil and controlling how much light reaches the retina.

Lens

The lens is a transparent structure inside the eye that works with the cornea to focus light on the retina. The lens can change shape, flattening to focus on objects far away and bending to focus on objects that are close.

Retina

The retina is a light-sensitive tissue that lines the back of the eye. It consists of rod and cone cells (photoreceptor cells). These cells collect the light signals directed onto them and send them as electrical signals to the optic nerve at the back of our eye.

Macula

The macula is the central part of the retina that allows us to achieve high-quality and central vision, helping us to read, drive safely and to see the world in detail and colour. The macula is yellow due to the collection of pigment from coloured fruit and vegetables we eat as part of our daily diet.

Fovea

The fovea is the centre of the macula which provides the sharp vision.

Choroid

The choroid is a layer containing blood vessels that lines the back of the eye; it is located between the retina and the sclera.

Sclera

The sclera is the white outer coat of the eye, surrounding the iris.

Optic Nerve

The optic nerve carries information as electrical impulses from the retina to the brain where the visual images are formed.

Vitrous

This is the clear, jelly-like substance found in the middle of the eye that helps to regulate eye pressure and shape.

How We See

From Light to Sight

Vision is not created by the eye alone - it is the result of communication between the eye and the brain.
The process involves:
Step 1

Light enters the eye.

Step 2

The retina captures light information.

Step 3

Photoreceptors convert light into electrical signals.

Step 4

Signals travel through the optic nerve.

Step 5

The brain interprets these signals as images.

How Our Eyes Work

Light (from the sun or an artificial light source) travels in a straight line. It bounces off objects and into our eyes. Light first passes through the cornea, the clear, dome-shaped surface that covers the front of the eye. The cornea bends (refracts) the incoming light, which then passes through the pupil. The iris, the coloured part of the eye, regulates the size of the pupil by stopping too much light from entering the eye when it is bright and maximising the amount of light entering the eye when it is dark. The light then passes through the lens, which focuses the light onto the back surface of the eye, the retina. The eye changes the shape of the lens as we look at far or near objects to keep them in focus – this is called accommodation.

The retina is the thin, delicate, photosensitive tissue that lines the back of the eye. It contains “photoreceptor” cells that convert light into electrochemical signals. The signals are processed and travel from the retina to the brain through the optic nerve, a bundle of about one million nerve fibres. The brain processes the signal to create the image that you see. The image received on the retina is actually upside-down – as an infant, our brains learn to invert the image so we don’t get confused.

Understanding the Retina

The Retina: Where Vision Begins

The retina plays a central role in vision. It acts like a biological camera sensor, capturing light and transforming it into information that the brain can understand.
Key Parts of the Retina
Macula

The macula is the central area of the retina responsible for:

  • Sharp vision
  • Reading
  • Recognising faces
  • Seeing fine details

Conditions affecting the macula may impact central vision.

Peripheral Retina

The outer areas of the retina support:

  • Side vision
  • Awareness of surroundings
  • Seeing in low-light conditions
Photoreceptors

Photoreceptors are specialised cells that detect light.

Rod cells

Support:

  • Night vision
  • Peripheral vision
  • Movement detection

Cone cells

Support:

  • Colour vision
  • Detailed central vision
Visual Function

Understanding Different Types of Vision

Vision is more than simply seeing clearly. Different parts of the visual system contribute to different aspects of sight.
Central Vision

Used for:

  • Reading
  • Recognising faces
  • Seeing details
  • Colour perception

Conditions affecting the macula may impact central vision.

Peripheral Vision

Used for:

  • Awareness of surroundings
  • Navigation
  • Detecting movement

Some retinal conditions primarily affect peripheral vision.

Night Vision

Night vision depends largely on rod cells.

Changes in retinal function can affect:

  • Seeing in dim environments
  • Adjusting between light and dark
Colour Vision

Colour vision depends on cone cells within the retina.

Changes affecting cone function may impact colour perception.

Retinal Health

Why Eye Health Matters

The retina plays a critical role in vision, and changes affecting retinal health can impact quality of life. While not all retinal conditions can be prevented, maintaining eye health and attending regular eye examinations can help protect vision.
Eye Health Actions
Attend regular eye examinations

Early detection and intervention are key in preventing sight loss.

  • Detect changes early
  • Monitor eye health
  • Support timely care

According to the American Optometric Association, a regular eye exam can also detect early symptoms of more than 270 chronic diseases and systemic conditions such as cancer, diabetes, autoimmune diseases, high blood pressure, and other health issues.

For more information on eye issues that may indicate larger health problems, as well as which health issues can be spotted during an eye exam, visit this comprehensive guide from MyVision.org.

Understanding changes in vision

Seek advice if you experience:

  • Sudden vision changes
  • New distortion
  • Flashes or floaters
  • Loss of vision
  • Difficulty seeing clearly
Maintaining overall health

This includes:

  • Maintaining a healthy diet
  • Quitting smoking
  • Limiting screen time
  • Wearing good quality sunglasses and/or protective eyewear

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