The pink eye or the red eye is a general term used by the people to refer to the infection of the Conjunctiva also called Conjunctivitis in medical terms. The other synonym is “Eye Flu”. Before dealing with “the pink eye or the conjunctivitis”, let us take an insight into as what conjunctiva is.
What is conjunctiva
Conjunctiva is a transparent membrane which covers the white of the eye and posterior or back part of the eyelids. The white portion of the eye is called sclera. The transparent membrane which would cover this sclera would be called conjunctiva. The back or the posterior portion of the eyelid is seen when we evert the eyelid.
The membrane covering this back portion of the eyelid is called the conjunctiva. Thus the conjunctiva covering the white or the sclera is also called the bulbar conjunctiva and the conjunctiva covering the posterior or back portion of the eyelid is called the palpebral conjunctiva and the junction between these two types of conjunctiva is called ‘fornix’ in singular and ‘fornices’ in pleural.
What protects the conjunctiva from infections and invasions?
There are some natural mechanisms which protect the conjunctiva from infections by the harmful microorganism. These are as follows:
1. The low temperature of the conjunctiva due to constant exposure to air. Any increase in the temperature would result in conditions favourable for growth of microorganisms.
2. Physical protection by the eyelids.
3. Flushing action of tears.
4. Lysosomes which are the enzymes present in tears which kill the bacteria.
5. There are some protective proteins in the tears called ‘immunoglobulins’ which protect the conjunctiva.
Any breach in these protective mechanisms and also other factors would lead to the pink eye or red eye or eye flu or conjunctivitis.
Types of conjunctivitis
1. Infective: due to infection by bacteria, virus, fungi, chlamydia or from granulomatous conditions like tuberculosis, syphilis, leprosy etc.
2. Allergic: from allergens like pollen, smoke, dust, drugs,or endogenous allergens etc.
Predisposing Factors or the factors that increase the risk of bacterial conjunctivitis are flies, poor hygienic conditions, poor sanitation and dirty habits. The disease is highly contagious.
Causative organisms include: Staphylococcus aureus, streptococcus pneumoniae, Streptococcus pyogenes, Haemophilus influenzae, Haemophilus aegyptius also called KOCH -Weeks Bacillus, Moraxella axenfeld, Pseudomonas pyocyanea, Neisseria gonorrhoeae, Corynebacterium diphtheriae.
Mode of Infection: Infection spreads through close contacts, can be airborne or waterborne through flies, by touching infected material, through infected fingers of the doctors, nurses, infected handkerchiefs, towels or infected opd instruments like tonometers. Infection can also take place from already existing infection of some other part of the eye such as infected lid or infected lacrimal sac.
Viral Conjunctivitis is caused by Adenoviruses, Herpes simplex virus type 1 and type 2, Picornaviruses, Poxviruses, paramyxoviruses.
Basic mechanism for development of symptoms
The mechanism is that of a basic inflammation. Mainly three sites are affected in the conjunctiva due to which the symptoms of the”pink or red” eye development. These sites are:
1. The blood vessels of the conjunctiva due to infection by the bacteria dilate and there is increase space between the cells of the blood vessels such that the fluid inside the blood vessels starts to leak which leads to oedema or swelling of the conjunctiva. Also capillaries begin to proliferate,so there is redness in the conjunctiva leading to the common name ” red eye or the pink eye”.
2. The neutrophils and other kinds of white blood cells, also called the inflammatory cells start to leak out from the dilated blood vessels into the conjunctiva leading to formation of mucopurulent discharge or the white pus like discharge from the eye which is another symptom of the “pink or red eye”.
3. Due to infection by the bacteria, some cells of the conjunctiva itself degenerate, these also form part of the discharge and as a result of the degeneration of these cells there is increase in number of mucin secreting goblet cells which also results in pus like consistency of the discharge.
2. Stickiness (morning stickiness characteristic of bacterial conjunctivitis).
3. Foreign body sensation or grittiness.
4. Lacrimation (watering from the eye).
5. Photophobia (sometimes).
6. Blurring of vision if cornea is involved.
1. Hyperaemia of the Conjunctiva: In bacterial conjunctivitis, it is usually seen more in Palpebral conjunctiva, fornices and peripheral part of bulbar conjunctiva.
In cases of angular bacterial conjunctivitis which is a chronic conjunctivitis caused by Moraxella axenfeld, there is a characteristic hyperaemia of the bulbar conjunctiva near the canthi and hyperaemia of the lid margins near the angles hence the name.
In case of Trachoma, there is congestion of upper tarsal conjunctiva (part of palpebral conjunctiva), and fornices.
2. Conjunctival Discharge: It is a prominent feature of conjunctivitis and is defined as formation of excessive secretion. It is mainly watery or mucoid in viral and allergic conjunctivitis, and purulent in bacterial conjunctivitis, it is ropy in a specific kind of allergic conjunctivitis, discharge is thick and copious and may even trickle down the cheeks in adult gonococcal conjunctivitis.
3. Follicles: They could be seen as yellowish white, round elevations in 1-2 mm in diameter and are seen in cases of trachoma, viral conjunctivitis particularly acute follicular conjunctivitis in cases of Epidemic keratoconjunctivitis, Acute herpetic conjunctivitis, Newcastle conjunctivitis, Pharyngoconjunctival fever.
They provide a particular red velvety appearance to the palpebral conjunctiva. They are particularly seen in adult Gonococcal Conjunctivitis, trachoma.
5. Subconjunctival Haemorrhage: It is due to rupture of conjunctival blood vessels. It is particularly seen in bacterial conjunctivitis caused by streptococcus pneumoniae, and acute haemorrhagic conjunctivitis caused by rna virus picornavirus ( Enterovirus type 70).
6. Chemosis: It is defined as the swelling (oedema) of the conjunctiva. It occurs due to the exudation from abnormally permeable capillaries and it is seen in all types of conjunctivitis. It is caused by the rubbing of eyes, viral infections and some allergies.
1. Topical Antibiotics: These are administered as eye ointments or eyedrops for mainly controlling the infection particularly in bacterial conjunctivitis. These include Gentamicin(0.3%), Ciprofloxacin or ofloxacin 0.3%) or Moxifloxacin(0.3%). These are given for application 3-4 times a day and eye ointment to be applied at night to prevent morning stickiness.
2. Systemic Antibiotics: That is oral or iv antibiotic must be given as the mainstay if the conjunctivitis is due to any systemic disease or microorganisms such as trachoma, gonococcal conjunctivitis, ophthalmia neonatorum etc.
3. Irrigation of the Conjunctiva: Irrigation is done with warm sterile saline once or twice a day to remove any harmful flakes or material. Earlier frequent eye wash was encouraged but now it is contraindicated because it will wash away the lysozymes in the tears which have a protective function.
4. No Bandaging should be done as it will increase the temperature of the conjunctiva due to non exposure of air and flare up the infection.
5. No Steroids should be applied in bacterial conjunctivitis as they flare up the infection.
6. Dark goggles can be worn to prevent photophobia.
7. Analgesics can be given to relieve the pain.
8. To prevent conjunctivitis, advocate hygienic practices.
9. Use separate handkerchiefs and towels.
10. Do not frequently rub the eye especially with dirty hands.
11. Wash hands before touching the eyes.
Other Causes of Red Eye
1. Causes in the Eyelid: Blepharitis, Trichiasis, Internal Hordeolum.
2. Causes in the Conjunctiva: Bacterial Conjunctivitis, Allergic Conjunctivitis, Viral Conjunctivitis, Toxic Conjunctivitis.
3. Causes in the Cornea: Corneal Ulcer (particularly bacterial), Exposure keratopathy.
4. Causes in the Sclera: Episcleritis, Scleritis.
5. Causes in the Uveal Tract: Anterior Uveitis.
6. Glaucoma (acute congestive narrow angle).
7. Endophthalmitis, Panophthalmitis etc.
1. A.K Khurana, MD “Ophthalmology” (New Age International Publisher, Inc 2012) p54-70.
2. Bulbar Conjunctiva image used on this page is copyright to Anatomy Atlases (www.anatomyatlases.org)
3. Palpebral Conjunctiva image is copyright to World Health Organization (www.apps.who.int)
4. Bacterial Conjunctivitis image is copyright to Mark J. Mannis and Ronald D. Plotnik (www.oculist.net)
5. Acute Haemorrhagic Conjunctivitis image is copyright to Mochizuki (www.fukushima-diary.com).
6. How to get rid of pink eye (www.cureforsure.us)