CORNEAL ULCER
An erosion in the cornea, the transparent outer part of the front of the eyes, is called a corneal ulcer. These ulcers can be very painful and, if they are left untreated, may cause scarring and lead to permanently impaired vision, blindness, or even loss of the eye. People who wear contact lenses are at increased risk of corneal ulcers.
WHAT ARE THE CAUSES?
Corneal ulcers maybe caused by an eye injury, an infection, or a combination of both. A relatively small injury such as a corneal abrasion (left), can develop into a corneal ulcer if the damaged area becomes infected. A more severe injury, such as that caused by a caustic chemical, can produce an ulcer in the absence of infection. However, an ulcer that becomes infected may enlarge and penetrate more deeply into the cornea. Only rarely do infections cause corneal ulcers without prior injury. The most common of these infections are herpes zoster, known as shingles, and herpes simplex infections.
WHAT ARE THE SYMPTOMS?
If you have a corneal ulcer, you may experience the following symptoms:
□ Intense pain in the eye.
□ Redness and discharge from the eye.
□ Blurry vision.
□ Increased sensitivity to light.
With an untreated infected ulcer, the infection may spread and permanently damage the vision in that eye and the eye itself. Consult your doctor immediately if you develop a painful, red eye along with blurry vision.
WHAT MIGHT BE DONE?
Your doctor may place fluorescein eye-drops in the affected eye and examine it under blue light, using a slit lamp. Doctor may also take a swab to identify the cause. If the dye reveals an ulcer, you may be given antibiotic or antiviral eye-drops to treat the infection. Even severe ulcers usually clear up within 1 -2 weeks of treatment, but they can leave scars that permanently affect vision.
TRACHOMA
Trachoma is a serious, persistent eye infection that often causes permanent scarring of the cornea, the transparent front part of the eye. Although rare in developed countries, trachoma is one of the World’s main causes of blindness. It affects about 400 million people, of whom about 6 million are blind.
Trachoma is due to the bacterium chlamydia trachomatis, which is spread to the eyes by direct contact with contaminated hands or by flies. Trachoma is common in poor parts of the world, particularly in hot, dry countries that have poor sanitation and limited water supplies. Overcrowding encourages the spread of the trachoma infection.
To avoid becoming infected in a high-risk area, you should wash your hands and face regularly and avoid touching your eyes with dirty fingers.
WHAT ARE THE SYMPTOMS?
Initially, trachoma causes inflammation of the conjunctiva, the membrane that covers the white of the eye and lines of the eyelids. Later symptoms include:
□ Thick discharge from the affected eye that contains pus.
□ Redness of the white of the eye.
□ Gritty sensation in the eye.
Over time, repeated episodes of trachoma can cause scarring on the inside eyelids. The scars may pull the eyelids inward and cause the eyelashes to rub against the delicate cornea. Left untreated, the condition can lead to blindness.
WHAT IS THE TREATMENT?
In the early stages, trachoma is treated with antibiotic eyedrops or ointment. If the cornea has become scarred, sight may be restored by an operation called a corneal graft, in which a cornea from a donor is used to replace the scarred one.
CATARACT
If you have a cataract, the normally transparent lens of the eye is cloudy as a result of changes in protein fibres in the lens. The clouding affects the transmission and focusing of light entering the eye, reducing clarity of vision.
If cataracts are present from birth, total loss of vision may result. However, cataracts do not usually affect children or young adults. Most people over age 75 have some cataract formation, but visual loss is often minimal as only the outer edges of the lens are affected.
Cataracts usually develop in both eyes, but generally one eye is more severely affected. A cataract in the central part of the lens or one that affects the whole lens can cause total loss of clarity and detail in vision. However, the affected eye will still be able to detect light and shade.
WHAT ARE THE CAUSES?
All cataracts occur as a result of structural changes to protein fibres within the lens. These changes cause part or all of the lens to become cloudy.
Changes in the protein fibres are a normal part of the aging process, but cataracts that develop earlier in life may occur because of an eye injury or from prolonged exposure to sun light. They may occur due to diabetes mellitus, uveitis, or long-term treatment with the chromosomal abnormality down syndrome.
WHAT ARE THE SYMPTOMS?
Cataracts usually develop over a period of months or years. In most cases, they are painless and usually cause only visual symptoms, such as:
□ Blurry or distorted vision.
□ Star-shaped scattering of light from bright lights, particularly at night.
□ Altered colour vision—objects appear reddish or yellow.
□ Temporary improvement in near vision in people who were farsighted.
A severe cataract may make the pupil of the eye appear cloudy.
WHAT MIGHT BE DONE?
Your doctor may examine your eyes with a slit lamp and an ophthalmoscope. If your vision is affected significantly, he may recommend that the cataract is removed surgically and an artificial lens put in the eye. If there is no other reason for your visual deterioration, your sight should improve greatly after the operation. However, you may still need to wear glasses afterward.