GLAUCOMA
Fluid continually moves into and out of the eye to nourish its tissues and maintain its shape. In glaucoma, the flow of fluid out of the eye becomes blocked and pressure inside the eye rises. This high pressure may permanently damage nerve fibres in the light-sensitive retina and in the optic nerve, which carries nerve signals from the retina to the brain. Glaucoma becomes more common with age, and mainly affects people over age 60. If untreated, the condition may cause blindness.
WHAT ARE THE TYPES?
There are two common types and two rare types of glaucoma. Acute glaucoma develops suddenly, causing rapid loss of vision and severe eye pain. In contrast, chronic glaucoma develops slowly and painlessly, often over many years. It may not cause noticeable symptoms until the eyes are badly damaged. Both types can run in families.
Secondary glaucoma occurs because of an underlying disorder, such as uveitis, or from using certain drugs such as corticosteroid eyedrops.
The other rare form, congenital glaucoma, is due to a defect in the drainage apparatus of the eye. Congenital glaucoma is present from birth and can lead to blindness. Secondary glaucoma can also result in blindness.
Glaucoma is diagnosed by measuring pressure in the eye using an instrument called a tonometer. Treatment should always be given urgently. Eyedrops are used first to reduce pressure in the eye. In some cases, surgery is then necessary to increase drainage of fluid and prevent the buildup of pressure in the eye. Correct treatment normally prevents further vision loss.
RETINAL DETACHMENT
The light-sensitive retina of the eye is normally attached to the underlying tissue, but in retinal detachment part of the retina peels away from this tissue. The condition usually affects one eye only but, without rapid treatment, can cause partial or total blindness.
Retinal detachment usually begins with a small tear in the retina. Fluid is then able to pass through the hole and separates the retina from the supporting tissues underneath. Tears may be caused by disorders such as severe near sightedness or eye injuries. In some people, tears appear as a result of scarring after a vitreous hemorrhage. Retinal detachment sometimes runs in families.
WHAT ARE THE SYMPTOMS?
Retinal detachment is painless, but its visual symptoms may include:
□ Flashing lights in the cornea of the eye.
□ Large numbers of dark spots in the field of vision.
If a large area of the retina has become detached, you may experience a cloudy ring or a black area across your field of vision. If you experience any of these symptoms, you should go to the emergency of your local hospital or call your doctor immediately.
WHAT MIGHT BE DONE?
Retinal detachment is diagnosed by ophthalmoscopy, which is a technique used to examine the eye’s internal structures. If only a small area of retina has detached, the tear may be sealed by laser treatment under local anesthesia. However, if a large area has detached, an operation under general anesthesia is necessary. If treated early, normal vision may be restored, but delayed treatment is less effective.
RETINOPATHY
Some long-standing diseases can damage small blood vessels throughout the body. If the blood vessels in the retina (the light-sensitive membrane at the back of the eye) are affected, the damage is known as retinopathy. Retinal damage varies according to the under lying disorder but can include leakage of blood from damaged vessels, loss of blood flow to some areas, and abnormal development of new blood vessels. Retinopathy may cause loss of vision.
One of the most common causes of retinopathy is diabetes mellitus. The condition can also occur as a result of high blood pressure, although vision is not usually affected in this case. Less frequently, retinopathy may be caused by AIDS, oxygen therapy in premature babies, or by sickle-cell anemia. Usually, only the underlying disease is treated. However, in diabetic retinopathy, laser surgery treatment of the retina itself can save vision.
EYE INJURIES
The eyelid-closing reflex and the bony socket around the eye help protect the eye from injury. However, eye injuries are still common, and in some cases blindness may result if the injuries are not treated promptly.
The most common injury to the eye is a scratch on the transparent cornea caused by a foreign body in the eye. Minor injuries of this type rarely damage vision permanently unless they develop an infection that remain untreated. However, penetrating injuries in which the eye is pieraced by a tiny, fast-moving object, such as a metal chip from machinery, can lead to total loss of sight. Blunt injuries, such as those due to a blow from a fist or ball, may also endanger vision. Injuries can also occur by using caustic chemicals or by looking directly at the sun.
Most eye injuries can be prevented by the use of protective eyewear when working with dangerous machines or chemicals or when participating in athletic activities. Never look directly at the sun, even while wearing sunglasses.
WHAT ARE THE SYMPTOMS?
The symptoms of eye injuries differ according to the type and severity of damage, but symptoms may include:
□ Pain and watering of the eye.
□ Inability to open the eye.
□ Bleeding under the front surface of the eye.
□ Bruising and swelling of the skin around the eye.
□ Reduced vision in the affected eye.
In the majority of minor eye injuries, first aid will often be helpful, but you should always seek medical attention for any eye injuries. If the injury was caused by a blow to the eye, involves a penetrating foreign body, or results in reduced vision, hold a clean, dry cloth over the injured eye and go to the nearest hospital emergency.
WHAT MIGHT BE DONE?
Your doctor will probably assess the eye by ophthalmoscopy and a slit lamp examination. Ultrasound scanning may also be used to look for a foreign body in the eye.
Most eye injuries only need treatment under local anesthesia, although some will require surgery under general anesthesia. Chemical injuries maybe treated with corticosteroids.
Most eye injuries heal completely with prompt treatment. Sometimes corneal injuries leave a scar, and, if the lens is damaged, part of it may become cloudy. Sunlight may cause permanent damage to the retina, and separation of the retina from its underlying layer due to a heavy blow requires urgent treatment to prevent loss of sight. A serious eye injury can cause permanent blindness.
STYE
An infection at the root of an eyelash may result in the formation of a pusfilled swelling called a stye. Most styes are caused by Staphylococcus aureus, a bacterium found on the skin of many healthy people. Adults are less likely than children to develop styes, but, if you use eye makeup or wear contact lenses, you may be at increased risk.
A stye begins as a red lump on the edge of the eyelid. Over the next few days, the eyelid becomes swollen and tender, and a yellow spot may form at the centre of the swelling.
WHAT IS THE TREATMENT?
Styes usually rupture, drain, and heal in a few days without treatment. You may be able to speed the process by placing a clean, warm, damp cloth on the stye for about 20 minutes, four times a day. To avoid infecting other people or reinfection yourself, always wash your hands after touching the infected eyelid and avoid sharing or reusing perosnal items such as towels or cloths.
If a stye does not heal in a few days or if the swelling becomes worse, see your doctor. He or she may prescribe a topical antibiotic, which should be put directly on the stye and the skin surrounding it. However, if the stye persists, you may also need to take an oral antibiotic, after which the stye should clear up within 2-3 days. Styes are unlikely to cause long-term damage, but they tend to recur in some people who are prone to them.