Red Eye

 Red Eye

PKGhatak, MD

Eyes develop from the forebrain as an extension of the central nervous system but mystics believe eyes are portals to the soul. Some others claim they can judge a man whether is innocent or guilty by looking into his eyes. Poets, writers and musicians love to associate eyes with all the beautiful things in this universe. Eyes are really remarkable by any measure.

But the physicians see the eyes as specialized organs but like other organs are subject to infection and diseases.

The tiny blood vessels on the surface of the layer of the eyes are colorless and the underlying layer is called the sclera which is the white of the eye. In the center of the sclera is a transparent cornea through which light passes without distortion to the retina where the process of vision begins.

Eyes turn red due to congestion of conjunctival blood vessels or actual rupture of blood vessels. The oxygen of air binds with hemoglobin separated by the thin layer, and so bleeding or congestion of conjunctiva looks so red. Some call it bloodshot eyes, commonly seen sleep deprived students before examinations, or those who had too much to drink at a fraternity party.

Red eyes are common in conjunctivitis, keratitis (inflammation of the cornea), corneal scratches, foreign bodies in the eyes, glaucoma, subconjunctival hemorrhage, chemical burns, and certain systemic diseases.

Conjunctivitis is of three categories: acute, chronic, and a part of systemic diseases.

Acute conjunctivitis: conjunctivitis can develop acutely from viral or bacterial, parasitic infections, or from chemical irritation like tear gas or pepper spray. Allergic red eyes are a common occurrence in spring and fall. There are many other causes of red eye.

Viruses.

Many viruses can produce conjunctivitis and common among them are Enterovirus, coxsackie, adenovirus, herpes virus, rubella and measles viruses. Rare but locally endemic viruses like Dengue, Hantavirus and Ebola can produce conjunctivitis. Ophthalmic herpes zoster is a serious disease that requires careful medical management.

Adenovirus 8,19 and 37 produce a severe type of acute painful conjunctivitis known as Keratoconjunctivitis. Enterovirus 70 and coxsackievirus A24 produce hemorrhagic conjunctivitis in tropical and subtropical countries. Herpes simplex can cause blisters on the conjunctiva.

Bacterial conjunctivitis.

In adults, a severe form of infection is seen in Neisseria gonorrhea and N. meningitis infection. Purulent discharges are loaded with bacteria and very contagious. The infection of the eyes spread very rapidly. Before the days of prenatal care, gonococcus eye infection in newborns took place during birth and was a major cause of infant blindness. Children are susceptible to H. influenzae, strep pneumonia, staphylococcus and Moraxella conjunctiva.

Chlamydia trachomatis produces recurrent conjunctivitis, scarring of the inner aspect of eyelids and cornea. It is common in the poorest parts of the world. It is an important cause of blindness and it is preventable by the timely administration of antibiotics. Reiter's syndrome is also produced by Chlamydia in young adults. This is a combination of arthritis, conjunctivitis and urethritis.

Chronic Conjunctivitis.

When conjunctivitis persists over 4 weeks it becomes chronic in nature and the eyelids are infected producing redness along the eyelashes and shedding of flake derbies and swelling of the eyelash margin. Common bacteria causing the chronic infection are streptococcus and Moraxella.

Allergic conjunctivitis.

Besides pollen, other common causes of allergic conjunctivitis are mascara, contact lens and lens solution, animal dander, molds, mites and cigarette smoke.

Vernal keratoconjunctivitis is an IgE mediated allergic, self limited but recurrent episodes of inflammation of the cornea and conjunctiva.

Dry eyes.

It is commonly seen in the elderly from decreased tear formation. In others chronic inflammation due to autoimmune disease, Sjogren's syndrome, scleroderma, psoriasis and use of cholinergic drugs. The dryness of conjunctiva produces a gritty sensation and burning sensation and produces redness of the eyes.

Subconjunctival hemorrhage. 

It is common in the elderly, particularly those taking Aspirin and blood thinners. Vigorous rubbing of eyes, staining like cough or sneezing ruptures blood vessels of the conjunctiva. Usually, one eye is affected. The patient may be alarmed but it is a benign condition and the blood disappears in a few days.

Transitional causes of red eyes.

Crying spell. hot showers, emotional upset, trauma, eye drops, dust or eyelashes in the eye, frequent touching of eyes.

Parasitic conjunctivitis.

Loiasis.

Loa loa is a nematode, a parasitic worm. Larvae of loa loa enter unman flesh through bites of a female deer fly and mango fly, called Chrysops demidita and C.silacia. The mature worms migrate through the body and at times pass underneath the conjunctiva and produce severe conjunctivitis. WHO estimates about 10 million people suffer from Loiasis.

Acanthamoeba.

It is a protozoan present in soil and tap water. If tap water is used to clean contact lenses then the infection may occur.

Damodex folliculorum. 

It is a mite, lives under the eyelashes and eyebrows. Infestation produces itching, red eyes and shedding of dry skin. It usually becomes chronic.

Toxoplasmosis.

Toxoplasma gondii is a facultative intracellular parasite, infection is usually acquired congenitally and immunosuppressed people can get infected from cat litter. The infection is mainly located in the retina but may also infect the cornea and conjunctiva.

Myiasis.

 A fly that usually feeds on Caribou called Botfly, can bite humans and lay eggs in the wound. Hatched eggs, maggots, feed on living human tissues. Maggots develop into adult worms and migrate throughout the body.  In the eyes, adult worms cause severe conjunctival inflammation, glaucoma and detached retina.  

Systemic diseases.

The following diseases are often associated with eye involvement and the red eye is just a part of them.

 Systemic Lupus Erythematosus, Rheumatoid Arthritis, Scleroderma. Temporal Arteritis, Periarterites Nodosa, Sarcoidosis, Migraine,

Venous obstruction. Central retinal vein occlusion, Superior vena cava obstruction, constrictive pericarditis.

Graves disease of the thyroid gland. Hyper-viscosity syndrome from multiple myeloma. Sickle cell disease. Serum sickness, Steven-Johnson syndrome, etc.

Glaucoma. Glaucoma is usually seen in the elderly but no group is immune from acquiring it, even a rare congenital form exists. In glaucoma, the hydrostatic pressure of the eyeball exceeds venous pressure resulting in damage of the retinal structure mainly in and around the Macula, a special area of acuity and color vision of the retina. This is a major cause of vision problems and blindness. Glaucoma is effectively treated before much damage has taken place.

*************************