Last updated date: 11-Feb-2023

Originally Written in English

All you need to know about Pinkeye

    Conjunctivitis, more commonly known as pinkeye, is the inflammation of eye mucosa secondary to bacterial or viral infections or to an allergic reaction. 

    A pinkeye viral or bacterial infection can be very contagious and is caused by germs that spread in the community in different ways. Whether you come into close personal contact, such as touching or shaking hands, or you touch your eyes before washing your hands after holding an object with germs on it pinkeye prevention is the best course of action if you’re trying to avoid getting infected. This article explores the causes of pink eye, its symptoms, and prevention strategies. 


    The basic structure of the eye

    There are multiple parts that make up the anatomy of the eye. These parts must work together in order to allow us to see clearly: the sclera is the main protector of the eyeball, and it has an opaque white color; the pupil is the dark spot at the center of the eye, and it allows light in; the iris is the colorful part of the eye surrounding the pupil; the cornea covers the iris and the pupil, and also provides protection. There are two more internal parts of the visual apparatus: a clear lens, behind the pupil, and the retina at the back of the eye. The conjunctiva is a thin membrane that covers the sclera and the inside of the eyelids. Its function is the production of mucus and tears and protection against microorganisms.


    Production of tears

    The tear film is comprised of three layers: an external lipid layer, a center fluid layer, and an inward mucous layer. The various organs that encompass the eye - different sorts of orbital glands - all contribute to the tear film. The meibomian organs and to a lesser degree the organs of Zeis and Moll discharge the lipids of the external layer. Other contributors to the tear film are the corneal and conjunctival epithelia. This type of tissue transports electrolytes and water, and alterations in the permeability of blood vessels that feed it may change the structure of the tear film.


    Common causes of pink eye

    Some of the most frequent etiological factors are represented by bacteria such as Staphylococcus aureus, or Streptococcus pneumoniae. Adenovirus is the most common cause of the infection, which is typically highly contagious and can be spread by contact with towels, linens, or even by close contact. Another cause of pinkeye in adults is Neisseria gonorrhoeae and Chlamydia trachomatis after sexual contact. Inoculation with the latter two can also occur in the perinatal period if the mother is infected, associating other risks, like neonatal sepsis and increased risk of spontaneous abortion.


    Staphylococcus aureus infections

    Out of all common staphylococcal bacteria, Staphylococcus aureus is the most dangerous one, being present on the skin and in the nose of many healthy adults, without ever causing any symptoms. Health workers or hospitalized people have a higher amount of bacteria on them than other people. Asymptomatic people who have these bacteria on them are called carriers. A carrier can infect an immuno-compromised person, causing, for example, pinkeye. Certain conditions can put you at risk of getting a staphylococcal infection: the flu, chronic disorders, tumors, transplants, or medical devices such as pacemakers, surgery, burns, diabetes, or undergoing radiation therapy. Infections caused by this bacterium may be difficult to treat, because of resistance to antibiotics. All staphylococcal skin infections have been proven to be extremely contagious, so certain activities such as handling food should be avoided.


    Streptococcus pneumoniae

    Also known by the name of pneumococcus, S. pneumoniae is a Gram-positive bacterium. It is the most frequent cause of pneumonia, and it resides in the respiratory tract, nose, and sinuses of healthy individuals. Although considered part of the normal respiratory flora, it can become pathogenic under the right conditions.


    Non-infectious pinkeye

    Non-infectious pinkeye

    Conjunctivitis may also occur for non-infectious reasons. The most common type of non-infectious pinkeye is allergic conjunctivitis. People with hay fever or other types of allergies typically deal with this health issue during allergies season. The second most common type is caused by different kinds of irritants, such as chlorine (swimming pools) or even air pollution. For this type of conjunctivitis, treatment usually consists of avoiding any further exposure to the irritant or the allergen.


    So, how can allergies affect your eyes? An allergy is ultimately a hypersensitive response of the immune system to a harmless external nonself molecule in the body, such as plant pollen, a specific food, or a medicine. Whatever the foreign material, or "allergen", the immune system reacts by initiating a specific form of immunological response as if it were responding to a real threat. This reaction can occur in any part of the body. Your immune system encourages the manufacture of antibodies termed Immunoglobulins because it believes it is dangerous to you. These antibodies cause an allergic reaction, causing your eyes to become swollen and uncomfortable.

    If your eyes become irritated when pollen begins to fall, you may have allergic conjunctivitis, also known as ocular allergy. When something you're allergic to affects your conjunctiva, it's called allergic conjunctivitis. Eye allergies are not threatening to your vision and they are not infectious. It’s not the same as pink eye, although the hyperemia of the conjunctiva may make it appear like it. On the other hand, allergic reactions can severely affect sufferers’ quality of life, still. When the weather gets hot, blurry vision and continuous scratching of the eyes can make it difficult to work and enjoy time outside. This can be extremely disheartening, which is why the majority of people who experience it seek help from their general practitioner.

    When this happens, a thorough eye exam will be performed by an optometrist or eye doctor. This exam will involve questioning your symptoms as well as a thorough examination of your eyes with eye tools to clear out any other problems. If your optometrist suspects seasonal allergies as the source of your eye irritation, he or she may recommend an allergy test. The results of your allergy test will indicate that your eye issues are caused by pollen or mold spores.


    SAC (seasonal allergic conjunctivitis) is the most frequent type of allergic conjunctivitis that affects the eyes. This type of conjunctivitis is more common in the spring and fall, when pollen from grass, trees, flowers, and ragweed is plentiful. On the palpebral conjunctiva area, the lids may be puffy and papillae may be present.


    Perennial allergic conjunctivitis (PAC) is a type of allergy that occurs all year. Animal dander, bug detritus, and dust mites are the most common causes. Because of the factors involved, these are also called environmental allergies.


    Pinkeye incubation period

    The incubation period refers to the amount of time between exposure to a certain pathogen, and the appearance of symptoms. For conjunctivitis, this timespan is between 24 to 72 hours. The reason this happens is that germs need to multiply in order to cause symptoms in an otherwise healthy person. For viral conjunctivitis, in this incubation period the virus is replicating, and it represents one of the stages of pinkeye. It is commonly known that viral pinkeye takes a longer time to heal and can cause more severe symptoms than the bacterial version. Also, the incubation period is shorter in toddlers and children than in adults.


    Pinkeye symptoms in adults

    Pinkeye symptoms in adults

    Normally, adults will have some of the following symptoms: 

    • runny eyes
    • itchy and swollen eyelids
    • waking up with a yellow or green discharge around the eyes that may cause lashes to stick together
    • a constant gritty feeling in the infected eye, which may be the first symptom you get. 

    More severe symptoms which require an urgent visit to the doctor’s office are intense sensitivity to light, pain, or pressure in or behind your eyes, high fever and chills, extremely blurred vision that doesn’t get better with blinking. Pinkeye symptoms should not cause extreme discomfort.


    Pinkeye symptoms in toddlers

    Pinkeye in babies may sometimes be difficult to assert, so if you suspect your child is suffering, the most important thing to do is see a doctor as soon as possible. If you’re not sure whether you should take your toddler to the doctor’s office, some of the giveaway signs may be the following:

    • your child may rub their eye, because of itchiness
    • constant blinking and eye movements, because of grittiness in the child’s eye
    • watery, yellow, or green discharge and sticky lashes in the morning or after sleeping
    • edema around the child’s eyes
    • sudden sensitivity to light

    Allergic and irritant pinkeye usually accompany other symptoms, like a runny nose and sneezing, while not causing pus formation or sticky lashes.


    Pinkeye treatment

    Pinkeye treatment

    Pinkeye medicine is usually centered on symptom relief. If you have a mild bacterial infection, it may go away on its own without the use of any medicine. Conversely, your doctor may prescribe antibiotics, usually, an ointment form or eye drops, for bacterial conjunctivitis. These may be necessary in case of infections that cause pus formation, or in immunocompromised patients. In the case of viral infections, antiviral medication may be prescribed, and the infection may clear up in 7 to 21 days. If you suffer from allergic conjunctivitis, there are many over-the-counter treatments for pinkeye that contain antihistaminic agents or mast cell stabilizers which will reduce redness and itchiness. Some pinkeye symptoms baby medicine may be prescribed in case your toddler is very uncomfortable and can’t sleep through the night.

    Other remedies that might help as well, can include:  

    • Artificial tears may be used for keeping the conjunctiva well hydrated. This will help with the sensation of grittiness or “sand in eye” that comes with conjunctivitis. 
    • Applying a wet cloth to the eyes may also ease the discomfort. 
    • For people who typically wear contact lenses, taking a break until the infection goes away may be advised.  


    Differential diagnoses

    Differential diagnoses

    Many conjunctivitis symptoms may be non-specific, which leads to the necessity of differential diagnosis. Conditions include the following:

    Atopic Keratoconjunctivitis (AKC) - Atopic keratoconjunctivitis (AKC) is a moderately uncommon but possibly blinding eye disease. Atopy occurs in 5 to 20% of the general population. It is more often found in men than women and it affects adults of all ages.


    Epidemic keratoconjunctivitis (EKC) - Epidemic keratoconjunctivitis (EKC) represents a type of conjunctivitis that is caused by adenoviruses. It is highly contagious and has a tendency to appear during epidemics. It is a self-limiting disease and treatment is usually symptomatic.


    Giant Papillary Conjunctivitis - Giant papillary conjunctivitis is also called contact-lens induced papillary conjunctivitis. Many contact-lens wearers suffer from this condition at least once during their lifetimes. All kinds of contact lenses can trigger this condition (rigid, hydrogel or silicone hydrogel, scleral, prosthetic, etc.).


    Herpes Simplex Virus (HSV) Keratitis – this disease is the most common cause of blindness due to illness of the cornea layer in the United States of America. If treated aggressively, the prognostic can be good. One of the first signs is the appearance of small bumps or clear vesicles. Most herpes simplex virus infections occur in adults, all over the world. It is estimated that one-third of the population suffers from recurrent infections. Herpetic keratitis in kids usually involves the corneal lining and stroma and is marked by a higher chance of bilateral disease, higher recurrence rate, and lazy eye.


    Superior Limbic Keratoconjunctivitis (SLK) – this condition represents the inflammation of the superior limbus of the bulbar conjunctival layer, keratitis, and hypertrophy. It has an excellent prognosis, with 100% remission rates, but symptoms may last for years before total resolution.


    Neonatal Conjunctivitis (Ophthalmia Neonatorum) – Neonatal conjunctivitis presents during the first month of life and it can be blinding, depending on the rapidity of treatment. The most common causes of neonatal conjunctivitis are bacteria such as Chlamydia (most frequent) and Neisseria (most severe). Babies can get this infection as they are being born through natural parturition.

    • Chlamydia trachomatis is a microorganism that causes a sexually transmitted disease (STD).

    It usually doesn’t cause any symptoms and is easily curable with antibiotics. If not treated promptly, it can spread to other areas of the human body and cause severe long-term health issues. Chlamydia is most commonly spread during unprotected vaginal, anal, or oral intercourse. Chlamydia can be spread from one person to the next through genital contact. If you come into contact with contaminated sperm or vaginal fluid, or if you get them in your eye, you can acquire chlamydia as well. Kissing, embracing, exchanging towels, or using the same restroom as someone with chlamydia will not spread the illness. Many persons who have chlamydia do not show any signs or symptoms. If you do show symptoms, they may not appear for some weeks after the disease. Others may go months without experiencing any symptoms.

    • The pathogen Neisseria gonorrhea is spread through sexual contact (STI). It was previously known as 'the clap.' Antibiotics can be used to treat and cure gonorrhea. If left untreated, gonorrhea can lead to infertility (the inability to produce offspring) as well as other health problems. Pregnant mothers can transmit the disease to their unborn children. If you're pregnant and suspect you have gonorrhea, you should get tested right away so you can be healed before the infant is born.


    FAQ - Here are some frequently asked questions by conjunctivitis patients 


    What to expect during an eye exam?

    You will first be asked if you have any vision or eye concerns. You'll be asked to describe the issues you're having, how long you've had them, and any circumstances that have helped or hurt them.

    Your eyeglass or contact lens history will be examined as well. The eye specialist will then inquire about your general wellbeing, including any medications you are taking and the medical history of your family.

    A common test is a Snellen chart. As your eyes go down the chart, you'll be told to read random letters that get tinier line by line. Some Snellen charts are video displays with text or images projected on them. If needed, the optician will position multiple lenses in front of your eye, one at a time, to see if you need glasses, and will ask you when the Snellen letters start becoming easier to read. This is referred to as refraction.

    Your vision will be clouded if you are administered eye dilating drops for the ophthalmoscopy. If so, wear sunglasses to shield your eyes from the sun, which can cause more damage while your pupils are dilated. Make arrangements for someone to drive you home. The effect from the drops normally disappears within a few hours.


    How common is pinkeye?

    In highly developed countries, infectious conjunctivitis is as common as 15 cases per 1000 patients that show up at the doctor’s office per year. This disease represents a major health issue in the developing world, even more so in countries or cities with poor public water supplies. Due to the highly contagious nature of the disease, more than 30 million people are affected by it outside of the United States. Another factor for this high number is the repeatability of infection – once infected, you can infect others and reinfect yourself. An example of a very severe type of bacterial conjunctivitis is trachoma and it represents the most preventable cause of blindness in the world, with more than 2 million cases of blindness or visual impairment per year.


    Can pinkeye cause fever?

    Fever is very unlikely with typical pinkeye. If you experience high fever, chills and other generalized symptoms, you should contact your doctor for a consultation.


    How to prevent pinkeye?

    There are several steps that you can take in order to prevent this highly infectious disease. The first and most important step revolves around washing your hands. Proper handwashing technique is important for good sanitization and it is comprised of five phases: wetting your hands with clean water, regardless of temperature, lathering your palms, the back of your hands, between your fingers and under your nails, scrubbing for at least twenty seconds, rinsing well under clean water, and drying your hands well with a clean towel. If you can’t use soap and water to wash your hands, you can use an alcohol-based sanitizer with at least 60% alcohol content.

    You have to pay extra attention when applying an infected child’s eye treatment or if you’re changing their sheets because you run the risk of getting infected, so you will have to thoroughly wash your hands after doing any of those things. If you cannot sanitize your hands, you must avoid touching your eyes with your hands. Do not share any personal items, such as eye makeup, face makeup, glasses, pillows, and towels with the infected person.


    Preventing the spread of pinkeye conjunctivitis    

    If you have pinkeye, the same sanitary rules apply, so washing your hands often is still the most important thing you can do to prevent reinfection and spread. However, even if your symptoms are mild, you should be cautious and avoid certain activities, such as going to a public swimming pool. Furthermore, since many pinkeye cases occur unilaterally, you should also avoid transmitting the infection to the healthy eye. To do so, make sure you wash your pillowcase as often as possible, be aware that makeup products like mascara, eyeshadow or even face brushes can spread the infection, and do not use the same eye drop dispenser for both your infected and your healthy eye. If you take all the necessary safety measures, there’s a high chance that you will not spread the infection to the people around you or to your healthy eye.



    Pink eye or conjunctivitis is not a life-threatening disease and normally will not leave any sequelae on your eyes, if you happen to become infected. The most important steps you can take to avoid infection are washing your hands thoroughly and making sure your hands stay away from your face as much as you can. Do not use someone else’s makeup brushes or mascara and try not to dry your face with unclean towels.