blindness among adults/elderly
It is a clouding of the natural lens, the part of the eye responsible for focusing light and producing clear, sharp images. The lens is contained in a sealed bag or capsule. As old cells die they become trapped within the capsule. Over time, the cells accumulate causing the lens to cloud, making images look blurred or fuzzy. For most people, cataracts are a natural result of aging. In fact, they are the leading cause of visual loss among adults 55 and older. Eye injuries, certain medications, and diseases such as diabetes and alcoholism have also been known to cause cataracts.
In the early stages of cataract it does not mean that the eye is blind. It is called ‘immature’ cataract. Eventually the lens becomes totally opaque, the eye goes blind and this is called a ‘mature’ cataract. Progression of lens opacities varies. Sometimes it matures in a few months others take years.
Causes of cataract
1) Aging-most common
2) Eye injuries
*perforating - may spread to involve the whole lens and
*non-perforating - may produce after a delay of some months or even years
3) Diabetes - irreversible
4) Secondary cataracts may develop after any other intraocular disease
5) Corticosteroid drugs used over a long period of time
6) Exposure to certain types of radiation. e.g. people working near furnaces may develop cataracts from infrared radiation.
Patients who have received radiotherapy may develop cataracts from x-rays.
7) Congenital cataracts may be present at birth
Symptoms of cataract
1) Gradual and progressive loss of visual acuity. When the cataract is mature there is only perception of light.
2) Dazzling occurs. In bright light the pupil constricts and the vision deteriorates. In dim light the pupil dilates, light enters the eye around the opaque part of the lens and the vision improves.
3) Refractive changes. Multiple images are caused by poor refraction of the lens. The patient sees one or more blurred ‘ghost’ images along with the true image.
Treatment of cataract
Numerous drops are available which claim either to stop or reverse the formation of cataract but there is no evidence that any of them work. There is however some unconfirmed evidence that taking very small doses of aspirin regularly may slow down the progress of cataract.
Basic treatment for cataract is surgical removal of the lens. The correct time for cataract removal is when the loss of vision has become a significant handicap to the patient.
Cataract extraction is the most common of all eye operations.
Two different ways in removing the lens:
1. Intracapsular – the entire lens is removed.
2. Extracapsular - the posterior capsule and suspensory ligament are left intact.
Pterygium is a raised, wedge-shaped growth of the conjunctiva. Occurs in the exposed part of the cornea between the eyelids in the 3 o’clock or 9 o’clock position. Stimulus to grow is excessive exposure to ultraviolet sunlight. It is most common among those who live in tropical climates or spend a lot of time in the sun.
Symptoms may include irritation, redness, and tearing.
Pterygiums are nourished by tiny capillaries that supply blood to the tissue. For some, the growth remains dormant; however, in other cases it grows over the central cornea and affects the vision. As the pterygium develops, it may alter the shape of the cornea, causing astigmatism. If the pterygium invades the central cornea, it is removed surgically.
Since pterygiums are most commonly caused by sun exposure, protecting the eyes from sun, dust and wind is recommended. Instilling artificial tears liberally is also helpful to decrease irritation. In some cases, steroid drops are prescribed to reduce inflammation.
Glaucoma is a disease caused by increased intraocular pressure (IOP) resulting either from a malformation or malfunction of the eye’s drainage structures. Left untreated, an elevated IOP causes irreversible damage to optic nerve and retinal fibers resulting in a progressive, permanent loss of vision. However, early detection and treatment can slow, or even halt the progression of the disease.