Conjunctivitis, also known as pink eye, is a common eye condition that affects all age groups. It is particularly common in children as viral conjunctivitis tends to spread rapidly in day care centers and schools. However, not all cases of conjunctivitis are due to an infection. Conjunctivitis may not always appear with typical symptoms and sometimes the only presenting symptoms may be similar to other eye conditions. Most of the time conjunctivitis is not a serious condition but sometimes it can extend to the cornea and affect vision.
Eye tissue is very delicate but unlike the rest of the body it is not protected by skin when the eyelids are open. The conjunctiva is a thin clear membrane that lines the outer part of the eye and the inner eyelid. It produces fluid (tears and mucus) which helps to lubricate the eye. In addition the conjunctiva protects the eye against foreign bodies and microbes when the eyelids are open, although the protection by the conjunctiva is limited.
How is conjunctivitis spread?
Conjunctivitis is either classified as infectious or non-infectious. Some causes of infectious conjunctivitis can be spread from one person to another, either directly or indirectly. Non-infectious causes cannot be spread but the same factors may affect many people in the same environment at the same time. Infectious conjunctivitis may be due to bacteria or viruses. Both can be spread through various means and may even cause outbreaks.
Read more on conjunctivitis.
The eye discharge from a person with infectious conjunctivitis may transmit the bacteria or virus when it comes into contact with another person’s conjunctiva. It can cause an infection of one or both eyes. Apart from sharing contact lenses, the discharge is rarely spread directly from eye to eye. Instead discharge on personal items like towels can carry the infectious agent and cause an infection in a person who uses the item.
Therefore people with infectious conjunctivitis must limit contact with others and not share personal items like towels. Children should not attend daycare or school until the infection resolves. Contact lenses should never be shared. In addition, contact lens users must clean the lenses as directed and not use it for extended periods of time if it was not intended to be used in this manner.
How to Diagnose Conjunctivitis
Most of the time conjunctivitis is diagnosed by the presenting signs and symptoms. A medical history may also help to identify the type and cause of the conjunctivitis. However, in some cases further diagnostic testing may be necessary. A sample of the eye discharge may be collected and sent to a laboratory for further investigation and culture. This can help to identify the species of bacteria that causes bacterial conjunctivitis.
This is a typical sign of conjunctivitis and the reason why it is called pink eye. The redness is due to the tiny blood vessels becoming dilated (wider) with more blood flowing through it. This is a typical feature of inflammation that occurs in all types of conjunctivitis, irrespective of the cause.
However, it is important to note that eye redness is not the only due to conjunctivitis. It can occur with many other conditions, such as eye strain or a blow to the eye. Therefore eye redness needs to be correlated with other symptoms before conjuntivitis is suspected.
Read more on eye redness.
Another common sign of conjunctivitis is excessive tearing. The conjunctiva produces both mucus and tears, although the tear production is much lower than that of the tear glands. When inflamed, the tear-producing cells of conjunctiva become overactive.
As a result the eyes become watery due to this increased tear production. However, the conjunctiva alone may not be the only part of the eye that is affected. If the tear glands are also inflamed then the excessive tearing may be highly pronouced leading to very watery eyes.
Itching and Grittiness
Itchy of the eye and grittiness are other common symptoms. Sometimes one of these symptoms may be more prominent than the other. The inflammation of the conjunctiva can trigger the itch receptors, hence the itching sensation even without any foreign irritant in the eye. This is also the reason for the gritty sensation.
Children tend to describe this as a ‘sand in the eye’ feeling. Both sensations tend to lead to profuse rubbing although this should be avoided as it tends to worsen the irritation. Since the conjunctiva extends to the eyelid, it is not uncommon for itching and grittiness to be felt in the inner part of the eyelid.
Eye pain is not always present in every case of conjunctivitis. It tends to be more prominent in chemical injury, with sharp foreign bodies and sometimes with a bacterial infection of the conjunctiva. Pain is a feature of inflammation, along with the redness, swelling and a sensation of heat over the eye. In addition, inflammation of the cornea (keratitis) which may occur with conjunctivitis can also contribute to eye pain.
Crusty Eye Discharge
Apart from excessive tearing, there may also be an eye discharge. The conjunctiva produces excessive mucus when inflamed. Unlike tears, the mucus does not flush away or evaporate as easily. Mucus is much thicker and sticky in texture. In bacterial conjunctivitis, the eye discharge may also be due to pus (purulent discharge).
The excessive mucus, and pus when present, may adhere to the eyelid and around the eyes. With air exposure, the discharge dries up and becomes crusty. This drying of the discharge tends to occur during the course of the night. By the morning, the dried discharge may hamper eyelid movement and it may be difficult to open.
Spongy Eye and Eyelid
As part of inflammation, the conjunctiva becomes swollen. This can extend to the cornea and also involve the sclera. It causes a spongy feeling when there is extensive swelling of the conjunctiva and surrounding eye tissue. The eyelids may also be inflamed in conjunctivitis depending on the cause. An inflamed eyelid is known as blepharitis. It may also have a spongy feeling due to the associated swelling.