Photoreceptors: Function, Types, and How to Care for Them

What are Photoreceptors?

Photoreceptors are cells in the retina that detect light and turn this light into electrical signals that are then sent to the brain. The retina is the light-sensitive layer at the back of the eye. There are two main types of photoreceptors; cone cells and rod cells. Cone cells are responsible for colour vision. Rod cells help people to see in low light conditions.

What are the Types of Photoreceptors?

There are two types of photoreceptors found in the retina; rod cells and cone cells. According to the American Academy of Ophthalmology, the retina has approximately 120 million rods and 6 million cones. Both rod cells and cone cells contribute to the process of converting light into electrical signals, that are then sent to the brain to help us see. The type of photoreceptors and their functions are listed below.

• Cone cells: Cone cells are a type of photoreceptor that provides colour vision.
• Rod cells: Rod cells are a type of photoreceptor that provide vision in low light conditions as well as peripheral vision.

What Eye Conditions Can Affect the Photoreceptors?

There are several eye conditions that can affect the photoreceptors including retinitis pigmentosa, cone dystrophy and colour blindness. The eye conditions that can affect photoreceptors are listed below.

• Retinitis Pigmentosa: Retinitis pigmentosa is a group of eye conditions that affect the retina, causing its cells to gradually break down. Retinitis pigmentosa changes how the retina responds to light and causes vision issues or vision loss. Symptoms of retinitis pigmentosa include loss of peripheral vision, loss of night vision, or loss of central vision.
• Cone Dystrophy: Cone dystrophy refers to a group of rare eye disorders that affect the cone cells. Cone dystrophy can cause symptoms such as decreased visual acuity, lack of colour perception and light sensitivity.
• Colour Blindness: Colour blindness is an eye condition in which a person struggles to distinguish between certain colours.

What Tests Can Be Done to Check Photoreceptors?

The main test used to check whether the photoreceptors are working properly is called an electroretinogram or an electroretinography. An electroretinogram measures the electrical response of the light-sensitive cells in the retina, or the rods and cones. According to the Mount Sinai Medical Organisation, an electroretinogram works by placing an electrical sensor or electrode on the eye which measures how the eye reacts to light stimulus. A light will then flash and the electrode will send the eye activity to a computer-like monitor. Another test that can be done to check how the photoreceptors are working, specifically cone cells, is a colour vision test. Issues with the cone cells may lead to colour blindness or colour vision deficiency. If a person is having trouble distinguishing colours, an optometrist may conduct a colour vision test. Colour vision tests can include the Ishihara test (colour plate test) and a colour hue test (colour arrangement test).

How to Take Care of Photoreceptors?

The way to take care of photoreceptors is to take care of eye health in general. The ways to take care of the health of your eyes, including the photoreceptors, are to get regular eye tests, eat a healthy and balanced diet, exercise regularly and not smoke. The ways to take care of the photoreceptors are listed below.

• Regular eye tests: Regular eye tests are a hugely important part of taking care of the overall health of the eyes, including the photoreceptors. Regular eye tests allow your optometrist to assess vision and the health of the eye, as well as detect, diagnose and monitor possible eye conditions.
• Eating a healthy and balanced diet: Eating a balanced diet is a way to take care of the eyes, including the photoreceptors. A healthy and balanced diet is described as a diet that is high in fruits and vegetables, whole foods, proteins and healthy fats. A healthy and balanced diet is good for your overall health and provides important nutrients to the eyes.
• Exercise regularly: Exercising regularly, whether walking, running, pilates or playing sports, is a good way to take care of overall health, including the health of the eyes and photoreceptors. Regular exercise helps reduce the risk of developing health conditions and eye conditions such as age-related macular degeneration (AMD).
• Not smoking: Not smoking is a way to take care of your overall health, as well as being of huge benefit to the eye, including the photoreceptors. Smoking has been linked to reduced eye functionality and an increased risk of several eye diseases, including age-related macular degeneration (AMD) and cataracts. Quitting smoking if you smoke, or not starting, is a good way to take care of the health of the eyes and the photoreceptors.