Disorders of the Conjunctiva

 

The conjunctiva is the thin, tough lining that covers the back of the eyelid and loops back to cover the sclera (the white of the eye). The conjunctiva helps protect the eye from foreign objects and infection but can itself become irritated by chemicals or allergic reactions or infected by viruses or bacteria. These conditions generally produce pain, itching, and redness on the surface of the eye.

Text A. Conjunctivitis

Conjunctivitis is an inflammation of the conjunctiva, usually caused by viruses, bacteria, or an allergy.

The conjunctiva can be inflamed by an allergic reaction to dust, mold, animal dander, or pollen and can be irritated by wind, dust, smoke, and other types of air pollution. It may also be irritated by a common cold or a bout of measles. The ultraviolet light of an electric welding arc, sunlamp, or even bright sunlight reflected by snow can irritate the conjunctiva.

Sometimes, conjunctivitis can last for months or years. This type of conjunctivitis may be caused by conditions in which an eyelid is turned outward (ectropion) or inward (entropion), problems with the tear ducts, sensitivity to chemicals, exposure to irritants, and infection by particular bacteria—typically chlamydia.

Symptoms and Diagnosis

When irritated, the conjunctiva becomes bloodshot, and a discharge often appears in the eye. In bacterial conjunctivitis, the discharge may be thick and white or creamy. In viral or allergic conjunctivitis, the discharge is usually clear. The eyelid may swell and itch intensely, especially in allergic conjunctivitis.

Usually conjunctivitis is easy to recognize because it commonly occurs with a cold or allergies. Sometimes, however, conjunctivitis resembles iritis, a more severe eye inflammation, or even acute glaucoma—serious conditions that can lead to a loss of vision. A doctor can usually distinguish the diseases. With the more serious eye conditions, the blood vessels closest to the colored part of the eye (iris) are very inflamed. Although conjunctivitis may cause a burning sensation, it's usually less painful than the more serious conditions. Conjunctivitis almost never affects vision unless the discharge temporarily covers the cornea.

Treatment

Treatment for conjunctivitis depends on the cause. The eyelids should be gently bathed with tap water and a clean washcloth to keep them clean and free of discharge. If the cause is a bacterial infection, antibiotic eyedrops or ointment may be prescribed. Sometimes the doctor takes a small sample of discharge with a cotton-tipped applicator for testing in a laboratory, then adjusts the prescription according to the test results. Corticosteroid eyedrops aren't used with antibiotics and should never be used by someone who might have a herpes infection because corticosteroids tend to make herpes worse.

Antibiotics don't help allergic or viral conjunctivitis. Antihistamines taken orally may relieve the itching and irritation. If not, corticosteroid eyedrops can help.

Because infective conjunctivitis is highly contagious, a person should wash the hands before and after bathing the eye or applying medication to it. Also, a person should be careful not to touch the infected eye and then touch the other eye. Towels and washcloths used to clean the eye should be kept separate from other towels and washcloths.

Surgery may be needed to correct the alignment of the eyelids or to open clogged tear ducts.

Inclusion conjunctivitis is a form of conjunctivitis caused by the bacterium Chlamydia trachomatis.

Newborns may be infected by their mother while passing through the birth canal; adults may be infected by being exposed to genital secretions containing the bacterium.

Symptoms and Treatment

About 5 to 14 days after birth, an infected newborn develops severe conjunctivitis with swelling of the eyelids and conjunctiva. A sticky discharge of pus runs from the eyes. Adults are usually infected in only one eye. The lymph nodes near the ear may swell. Occasionally, the condition damages the cornea, causing cloudy areas and a growth of blood vessels. Antibiotics usually don't reverse such damage, but they may help prevent it if they're given early.

Half of the children who have this condition also have a chlamydial infection of the throat and nose, and about 10 percent develop pneumonia. Regardless of the extent of infection, the antibiotic erythromycin generally cures it. In adults, erythromycin or other antibiotics, such as tetracycline and doxycycline, can be used. The mother of an infected child or the sex partner of an infected adult should also be treated.

Notes:

mould air pollution turn outward, inward discharge adjust alignment inclusion conjunctivitis

плесень; плесенный грибок загрязнение воздуха выворачиваться наружу, внутрь выделение регулировать, выверять выравнивание бленнорея с включениями

Text B. Trachoma

 

Trachoma (granular conjunctivitis, Egyptian ophthalmia) is a prolonged infection of the conjunctiva caused by the bacterium Chlamydia trachomatis.

Trachoma is common in poverty-stricken pars of the dry, hot Mediterranean countries and Far East. It occurs occasionally among people in mountainous areas of the southern United States. Trachoma is contagious in its early stages and may be transmitted by eye-hand contact, by certain flies, or by contaminated articles such as towels and handkerchiefs.

Symptoms and Treatment

In the early stages of the disease, the conjunctiva is inflamed, reddened, and irritated, and a discharge appears. In the later stages, the conjunctiva and cornea become scarred, causing the eyelashes to turn inward and vision to become impaired.

When trachoma is suspected, a doctor swabs the eye or scrapes the area to obtain a specimen, which is sent to a laboratory, where the infecting organism is identified. Treatment consists of applying antibiotic ointments containing tetracycline or erythromycin for 4 to 6 weeks. Alternatively, these antibiotics can be taken orally. If the condition causes deformities of the eyelid, conjunctiva, or cornea, surgery may be needed.

 

Notes:

poverty-stricken	бедствующий, сильно нуждающийся
swab	смазывать, наносить тампоном
specimen	образец, препарат (для исследования)

 

Corneal Disorders

 

The cornea, the domed covering in the front of the eye that protects the iris and lens and helps focus light on the retina, consists of cells and fluid and is normally clear. Corneal disease or damage can cause pain and a loss of vision.

Text.

Corneal Ulcer. A corneal ulcer is a pitting of the cornea, generally from an infection by bacteria, fungi, viruses, or the protozoan Acanthamoeba, and sometimes from an injury.

Bacteria (often staphylococci, pseudomonades; or pneumococci) can infect and ulcerate the cornea after the eye is injured, a foreign object lodges in the eye, or the eye is irritated by a contact lens. Other bacteria, such as gonococci, and viruses, such as herpes, can also cause corneal ulcers. Fungi may cause slowly growing ulcers. Rarely, vitamin A or protein deficiency may lead to corneal ulceration.

When the eyelids don't close properly to protect and moisten the cornea, corneal ulcers may develop from dryness and irritation, even without an infection.

Symptoms and Treatment

Corneal ulcers cause pain, sensitivity to light, and increased tear production, all of which may be mild. A whitish yellow spot of pus may appear in the cornea. Sometimes, ulcers develop over the entire cornea and may penetrate deeply. Additional pus may accumulate behind the cornea. The deeper the ulcer, the more severe the symptoms and complications.

Corneal ulcers may heal with treatment, but they may leave a cloudy, fibrous material that causes scarring and impairs vision. Other complications include deep-seated infection, perforation of the cornea, displacement of the iris, and destruction of the eye.

A corneal ulcer is an emergency that should be treated immediately by an eye doctor (ophthalmologist).To see an ulceration clearly, a doctor may apply eyedrops that contain a dye called fluorescein. Antibiotic therapy and surgery may be required.

Herpes Simplex Infection. When a corneal herpes simplex infection (herpes simplex keratoconjunctivitis, keratitis) begins, it may resemble a mild bacterial infection because the eyes are slightly painful, watery, red, and sensitive to light. Corneal swelling makes vision hazy. However, the herpes infection doesn't respond to antibiotics, as a bacterial infection would, and often it continues to worsen.

Most often, the infection produces only mild changes in the cornea and goes away without treatment. Rarely, the virus deeply penetrates the cornea, destroying its surface. The infection may recur, further damaging the surface of the cornea. Several recurrences may result in ulceration, permanent scarring, and a loss of feeling when the eye is touched. The herpes simplex virus can also cause an increased growth of blood vessels, visual impairment, or total loss of vision.

A doctor may prescribe an antiviral drug such as trifluridine, vidarabine, or idoxuridine. These drugs are usually prescribed as an ointment or a solution to be applied to the eye several times a day. However, they're not always effective; sometimes, other drugs must be taken by mouth. Sometimes, to help speed healing, an ophthalmologist may have to gently swab the cornea with a soft cotton-tipped applicator to remove dead and damaged cells.

Herpes Zoster Infection. Herpes zoster is a virus that grows in nerves and may spread to the skin, causing shingles. The condition doesn't necessarily threaten the eye, even when it appears on the face and forehead. But if the ophthalmic division of the fifth cranial nerve (trigeminal nerve) becomes infected, the infection is likely to spread to the eye. The infection produces pain, redness, and eyelid swelling. An infected cornea can become swollen and severely damaged and scarred. The structures behind the cornea can become inflamed, a condition called uveitis, and the pressure in the eye can increase, a condition called glaucoma. Common complications of a corneal infection include a lack of feeling when the cornea is touched and permanent glaucoma.

When herpes zoster infects the face and threatens the eye, early treatment with acyclovir taken by mouth for 7 days reduces the risk of eye complications. Corticosteroids, usually in eyedrops, may also help. Atropine drops are often used to keep the pupil dilated and help keep pressure in the eye from increasing. People over age 60 who are in generally good health may find that taking corticosteroids for 2 weeks helps prevent the pain that may occur after the herpes sores disappear; this pain is called postherpetic neuralgia.

Notes:

whitish	беловатый, белесоватый, белесый
impairment	ухудшение; повреждение
shingles	опоясывающий лишай
lack	нехватка, недостаток

Cataracts

 

Text.

A cataract is cloudiness (opacity) in the eye's lens that impairs vision.

Cataracts produce a progressive, painless loss of vision. Their cause usually isn't known, although they sometimes result from exposure to x-rays or strong sunlight, inflammatory eye dis­eases, certain drugs (such as corticosteroids), or complications of other diseases such as diabetes. They're more common in older people; babies can be born with cataracts (congenital cataracts).

Symptoms

Because all light entering the eye must pass through the lens, any part of the lens that blocks, distorts, or diffuses light can cause poor vision.

How much vision deteriorates depends on where the cataract is and how dense (mature) it is.

In bright light, the pupil constricts, narrowing the cone of light entering the eye, so that it can't easily pass around the cataract. Thus, bright lights are especially disturbing to many people with cataracts, who see halos around lights, glare, and scattering of light. Such problems are particularly troubling when a person moves from a dark to a brightly lit space or tries to read with a bright lamp. People with cataracts who also take glaucoma medication that constricts the pupils may have greater vision loss.

A cataract at the back of the lens (posterior subcapsular cataract) particularly interferes with vision in bright light. It affects vision more than other cataracts because the opacity is at the point where light rays cross.

Surprisingly, a cataract in the central part of the lens (nuclear cataract) may improve vision at first. The cataract causes light to be refocused, improving vision for objects close to the eye. Older people, who generally have trouble seeing things that are close, may discover that they can read again without glasses, a phenomenon often described as gaining second sight.

Although cataracts usually aren't painful, rarely they cause swelling in the lens and increased pressure in the eye (glaucoma), which can be painful.

Diagnosis and Treatment

A doctor can see a cataract while examining the eye with an ophthalmoscope (an instrument used to view the inside of the eye). Using an instrument called a slit lamp; a doctor can see the exact location of the cataract and the extent of its opacity.

Usually, people who have a cataract can determine when to have it surgically removed. When people feel unsafe, uncomfortable, or unable to perform daily tasks, they may be ready for surgery. There's no advantage to having surgery before then.

Before deciding on surgery, a person with a cataract can try other measures. Eyeglasses and contact lenses may improve vision. For certain kinds of cataracts in people who don't have glaucoma, medications that keep the pupil dilated may help. Wearing sunglasses in bright light and using lamps that provide reflected lighting rather than direct lighting decrease glare and aid vision.

Cataract surgery, which can be performed on a person of any age, usually doesn't require general anesthesia or an overnight hospital stay. During the operation, the lens is removed, and usually a new plastic or silicone lens is inserted; this artificial lens is called a lens implant. Without a lens implant, people usually need a contact lens. If they can't wear a contact lens, they can try eyeglasses, which are very thick and tend to distort vision.

Cataract surgery is common and usually safe. Rarely, after the operation, a person may develop an infection or a hemorrhage in the eye, which can lead to a serious loss of vision. Older people in particular should make arrangements in advance to get extra help at home for a few days after surgery. For a few weeks after surgery, eyedrops or ointment is used to prevent infection, reduce inflammation, and promote healing. To protect the eye from injury, the person wears glasses or a metal shield until healing is complete, usually a few weeks. The person visits the doctor the day after surgery and then typically every week or two for 6 weeks.

Sometimes people develop an opacity behind a lens implant weeks or even years after it is implanted. Usually, such an opacity can be treated with a laser.

 

Notes:

cloudiness	помрачение
deteriorate	ухудшать
scattering	рассеивание
gaining second sight	прирост ясного видения
slit lamp	щелевая лампа
glare	ослепительный яркий свет; сияние
shield	защита

 

Retinal Disorders

 

The retina is the light-sensitive membrane on inner surface of the back of the eye. The optic nerve extends from the brain to about the center of the retina and then branches out. The central area of the retina called the macula contains the highest density of light-sensing nerves and thus produces the sharpest visual resolution. The retinal vein and artery reach the retina near the optic nerve and then branch out, following the paths of the nerves. Like the optic nerve and its branches, the retina itself has a rich supply of vessels that carry blood and oxygen.

The cornea and lens near the front of the eye focus light onto the retina. Then the branches of the optic nerve sense the light, and the optic nerve transmits it to the brain, where it's interpreted as visual images.