1300 164 990
Cornea: Anatomy, Function, and Associated Eye Problems
Published on January 19th, 2024
Updated on September 10th, 2024
Australia
The cornea is a very important part of the eye’s anatomy. The cornea is the outermost layer of the eye, protecting the structures in the eye. Another cornea function is to focus light that enters the eye, helping the human eye see. The anatomy of the cornea consists of five layers which are the epithelium, Bowman’s layer, the stroma, Descemet’s membrane and the endothelium. Eye problems related to the cornea, also known as corneal diseases, include keratitis, corneal dystrophy, dry eyes and eye injuries.
What is the Cornea?
The cornea is the outermost part of the eye that acts as a protective covering for the structures inside the eye. It is a transparent structure that covers the iris, pupil and anterior chamber. The cornea also functions by bending and refracting light that the eye receives.
The cornea is composed of five layers, the epithelium, Bowman’s layer, the stroma, Descemet’s membrane and the endothelium. Keep reading to learn more about what is a cornea.
Are Cornea and Corneal the Same?
Cornea describes a part of the eye’s anatomy that is located at the front of the eye and corneal refers to anything concerning the cornea such as corneal diseases.
What is the Structure of the Cornea?
The cornea is a transparent structure that is located at the front of the eye. The structure of the cornea is made up of five layers which are the epithelium, Bowman’s layer, the stroma, Descemet’s membrane and the endothelium. Below is an image demonstrating the five layers of the cornea.
What is the Cornea Made of?
The cornea is made of cellular and acellular components which include keratocytes, epithelial cells, endothelial cells, collagen and glycosaminoglycans, according to an article published in the National Library of Medicine titled, Anatomy of cornea and ocular surface.
Is the Cornea the Most Sensitive Eye Part?
Yes, the cornea is considered to be the most sensitive structure in the eye as it has the greatest density of nerve fibres of any tissue in the human body, according to an article titled, The Sensitivity of the Cornea in Normal Eyes by Michel Millodot, published in Frontiers in Visual Science.
Where is the Cornea Located?
The cornea is located at the front of the eyeball and covers the iris, pupil and anterior chamber. Due to its location as the outermost part of the eye, it acts as a protective shell for the structures inside the eye.
What are the Different Layers of the Cornea?
Five main layers of the cornea make up the anatomy of the cornea. The cornea layers are the epithelium, Bowman’s layer, stroma, Descemet’s membrane and the endothelium. These layers and their definitions are listed below.
- Epithelium: The epithelium is the cornea's outermost layer and stops materials from entering the eye.
- Bowman’s layer: Bowman’s layer is located directly under the epithelium layer and consists of protein fibres known as collagen.
- Stroma: Stroma is the next layer of the cornea, under Bowman’s layer and is the thickest layer.
- Descemet’s membrane: Descement’s membrane is a strong but thin layer of the cornea and functions as a barrier against eye injuries and infection.
- Endothelium: The final, innermost layer of the cornea is called the endothelium, which is a very thin cell layer.
1. Epithelium
The epithelium is the cornea's outermost layer and stops materials from entering the eye. The epithelium is important as it absorbs nutrients and oxygen from tears. These nutrients are then distributed to the rest of the cornea through the epithelium layer.
2. Bowman's Layer
Bowman’s layer is located directly under the epithelium layer. This transparent layer of tissue consists of protein fibres known as collagen, according to the Ophthalmic Consultants of Vermont. Bowman’s layer is strong as it keeps the cornea from swelling forward.
3. Stroma
Stroma is the next layer of the cornea, under Bowman’s layer and according to the article, Anatomy of cornea and ocular surface, published in the National Library of Medicine, it accounts for approximately 80%-90% of the cornea’s thickness.
4. Descemet's Membrane
Descement’s membrane is a strong but thin layer of the cornea and functions as a barrier against eye injuries and infection. According to the Ophthalmic Consultants of Vermont, this layer is primarily comprised of collagen fibres.
5. Endothelium
The final, innermost layer of the cornea is called the endothelium, which is a very thin cell layer. This is a crucial layer as it stops the cornea from getting too wet by pumping excess fluid out of the stroma.
What is the Function of the Cornea in the Eye?
There are three main functions of the cornea in the eye. The first function is protecting the structures inside the eye, acting as a protective shell on the outside of the eye. The next function is contributing to the refractive power of the eye which means it refracts or bends light as it enters the eye. Finally, the cornea focuses light onto the retina as it enters the eye, with minimum optical degradation and scatter according to the National Library of Medicine.
How Does the Cornea Help the Human Eye See?
The cornea helps the human eye see as it helps the eye focus by refracting light that enters the eye, according to the Cleveland Clinic. The cornea is the first contact light has with the human eye and serves to focus the majority of the light the eye receives. The cornea also protects the eye by filtering out harmful glare such as ultraviolet rays from sunlight.
What are the Eye Conditions that Can Affect the Cornea?
Corneal diseases are a categorisation of eye conditions that affect the cornea. The conditions that affect the cornea include keratitis, corneal dystrophy, dry eyes and eye injuries. These eye conditions and their definitions are listed below.
- Keratitis: Keratitis is a corneal condition that is characterised by inflammation of the cornea caused by an infection or an injury to the eye. Symptoms of keratitis include red eyes, blurry vision and eye pain. Keratitis is mainly treated with eye drops.
- Corneal Dystrophy: Corneal dystrophy refers to a group of rare conditions that cause changes to the shape of the cornea. Some forms of corneal dystrophy can cause vision loss and pain. This eye condition can be treated with laser treatment.
- Dry Eye: Dry eye is a condition where tears are unable to properly lubricate the eyes. According to Johns Hopkins Medicine, if dry eye is left untreated, it can cause lasting damage to the cornea and a decline in vision. Dry eye symptoms include blurry vision, burning eyes and red eyes.
- Eye Injuries: Eye injuries that affect the cornea can be considered corneal conditions. A corneal abrasion is a type of eye injury that occurs when there is a scratch or tear on the cornea that may be caused by foreign bodies in the eye such as wood chips or sand.
Are Corneal Diseases Common in Older People
Corneal diseases can affect a range of individuals, including older people. People around the age of 20 and above can develop corneal diseases, however, many corneal diseases are rare and, therefore, are not commonly experienced. Common corneal diseases include keratitis and corneal abrasions with rare conditions being corneal ectasia and iridocorneal endothelial syndrome.
How to Take Care of Your Cornea?
To take care of your cornea, you should book regular eye tests with an optometrist who can monitor the health of your eyes as well as your vision. This allows them to detect eye diseases early which can be crucial in preventing vision loss. You should also not smoke as it can negatively impact your eye health including your cornea. Finally, it is essential to wear sunglasses whenever you are outside to protect your eyes from the UV rays emitted by the sun. Sun exposure is thought to be one of the causes of a pterygium which is a corneal condition.
What is the Importance of an Optometrist in Diagnosing Corneal Conditions?
Optometrists play a crucial role in diagnosing corneal conditions and maintaining eye health. Optometrists can diagnose many eye conditions through regular eye tests by assessing the patient’s vision and eye health. For more complex corneal conditions, an optometrist will refer patients to an ophthalmologist for further treatment. The importance of an optometrist demonstrates why eye tests are necessary for taking care of your eyes.
How Important is a Regular Eye Test for the Cornea?
Regular eye tests are very important for maintaining the health of your cornea as well as your overall eye health. Regular eye tests allow your optometrist to monitor any changes in your vision or eye that could indicate signs of a corneal condition or other eye condition. We recommend everyone have an eye test at least every two years and if you are over the age of 65, then a yearly review is advised.
Can You Still See Without a Cornea?
A clear, healthy cornea is necessary for good vision, according to the American Academy of Ophthalmology. A corneal transplant may be a necessary option for people with a scarred or swollen cornea that affects their vision. In a corneal transplant, the damaged cornea is removed and replaced with a clear donor cornea.
How Can Oscar Wylee Help You Take Care of Your Cornea?
Oscar Wylee can help you take care of your cornea as our optometrists are available in-store to provide comprehensive eye tests to assess your vision and eye health. They will examine your cornea as well as the other structures of your eye to determine if there are any signs of corneal conditions or other eye conditions.
Does Wearing Prescription Eyeglasses Help Protect the Cornea?
While prescription glasses will not specifically protect the cornea, glasses and sunglasses in general can prevent dirt or debris from entering the eye and potentially scratching the cornea, known as a corneal abrasion. The main reason for wearing prescription eyeglasses is to correct a person’s vision so they can see clearly and comfortably, not to protect their cornea.
What is the Difference Between the Cornea and the Conjunctiva?
The cornea and the conjunctiva are different parts of the eye’s anatomy and have their own functions and different makeup. The conjunctiva is a thin layer of tissue that covers the whites of the eye and also lines the inside of the eyelid. The conjunctiva secretes fluids that keep the eyes lubricated and protected from infections as well as outside bacteria and bodies including dust and debris. The cornea is the clear outer layer at the front of the eye and controls how much light passes through the eye while also protecting the structures inside the eye.
What is the Difference Between the Cornea and the Sclera?
The cornea and the sclera are both parts of the eye’s anatomy and have similarities and differences. According to an article published in the National Library of Medicine, the cornea and sclera constitute the outer covering of the eyeball and both protect the structures inside the eye. The sclera is located at the back of the outer covering, whereas the cornea is located at the front.
Read Cornea: Anatomy, Function, and Associated Eye Problems in other Oscar Wylee regions and their languages.
Australia