Retina of the Eye

What is the Retina?

The retina is a thin tissue lining the inside back wall of the eye. Within the retina are millions of light-sensitive cells known as cones and rods.

Rods and cones receive visual information and send signals to the brain for interpretation. This enables you to see.

For you to see clearly, the cornea and lens must focus light rays precisely on the retina.

Anatomy

The human retina measures 30 to 40 mm and covers roughly 1,100 square mm in each eye.¹ 

The retina is about 0.5 millimeters thick. It’s thicker towards the optic nerve head and increasingly thinner at the ora serrata. 

The ora serrata is the junction between the non-light-sensitive area and the light sensitive area of the retina.

During an eye examination, an ophthalmologist will look at the following important parts of the eye:

The Posterior Pole

The posterior pole is the back part of the retina that includes the macula and optic nerve.²

The optic nerve is a bundle of fibers that transmit visual messages to the brain for interpretation, which enables you to see.³

Macula

The macula is 5mm in diameter and is responsible for your central vision, color vision, and fine detail.

The macula contains a high concentration of photoreceptor cells (cones and rods).

Optic Nerve Head

Also known as the optic disc, the optic nerve head is the face of the optic nerve bundle as it enters the back of the eye.

It allows the exit of the retinal ganglion cell axons and the entry and exit of the retinal blood vessels. 

Ganglion cell axons are long fibers that make up the optic nerve.

Functions

The retina functions much like a camera. The Images come in through the cornea and eye lens and are focused on the retina. 

The retina converts the images into electrical signals.⁴ The signals are then sent to the brain through the optic nerve.

The brain interprets the signals into images, enabling you to see the shape, design, color and other details of the objects you look at.

Retinal Problems & Diseases

Retinal diseases vary widely, and they can affect any part of your retina. In most cases, visual issues may occur.

Below are common retinal problems:

Diabetic retinopathy

If you have diabetes, the tiny blood vessels at the back of your eye may weaken and leak into the retina, causing it to swell. This may affect your ability to see.

Macular degeneration

Macular degeneration affects the center of the retina.

This affects central vision, causing a blurry, distorted view or a blind spot at the center of your visual field.

Retinal Tear or Detachment

A retinal tear or detachment occurs when the retina is torn or detached from other parts of the eye that provide nourishment and function.

A retinal tear or detachment is considered an ocular emergency.

Central Serous Retinopathy (CSR)

CSR is a condition where a cyst develops in the central retina. This leads to distorted vision.

This condition mainly affects men in their 30s and 40s.⁵

Macular hole

This is a minor defect characterized by a small hole at the center of the macula. The hole may develop due to trauma or abnormal traction within the eye.

Retinitis Pigmentosa

This is a rare genetic disorder that involves loss of retinal cells.⁶ 

Retinitis pigmentosa causes night blindness and loss of side vision (peripheral vision)

When to See a Doctor

Seek medical advice if you experience flashes, reduced vision, floaters, or persistent pain in your eye.

Treatment Options

Treatment for retinal diseases is focused on either stopping or slowing the progression of damage, improving or restoring your vision, or managing a chronic condition.

They include:

• Laser surgery. Used to repair retinal holes.
• Scatter laser photocoagulation. This is the shrinking of abnormal cells, such as in the case of diabetic retinopathy.
• Cryopexy. This is a freezing process used to treat retinal tears. Cryopexy involves freezing the retina to allow healing.⁷
• Air or gas injection (pneumatic retinopexy). This may be used together with cryopexy or laser photocoagulation to treat retinal detachment.
• Scleral buckle. It’s used to repair retinal detachment using silicone material. 
• Injection of medicines. Your eye doctor may suggest injecting medication into your eye. This is common, especially if you have wet macular degeneration or diabetic retinopathy.
• Retinal implants. If you have severe vision loss, your retinal specialist may suggest surgery. The surgery involves implanting a tiny electrode chip or retinal prosthesis into the retina. 
• Vitrectomy. This involves the replacement of the vitreous to prevent further damage to the retina. 

Why Routine Eye Exams are Important 

During routine eye examinations, your eye doctor examines for signs of any defects or diseases. These include macular degeneration, detached retina, your ability to see, and more.

Regular examinations enable your doctor to detect any issues early before they become serious. Most eye issues are treatable during the early stages.

Your eye doctor will also offer you some medical education regarding eye health. This will help you detect any issues once they occur.

Other Parts of the Eye

Other important parts of the eye include:

• The cornea. The clear bulging surface of the eye.
• Sclera. The white part of the eye.
• Conjunctiva. Covers the sclera.
• Iris. The color part that surrounds the pupil.
• The lens of the eye. Clear part of the eye that helps to focus.
• Pupil. Opening through which light passes into the eye.
• Vitreous Humor. The fluid-filled space between the lens and the retina.