A cataract is a clouding of the lens, converging lens located inside the eye. This clouding is responsible for a gradual reduction of vision, accompanied by early embarrassment to light (photophobia). This decrease in vision may be rapid (few weeks) due to trauma.
This disease is known since antiquity (it is observed both in animals than humans). It has been described in various forms and often used painting from Claude Monet to illustrate how it can influence the perception of images and colors (Monet painted series of the same subject over the years while his illness distorted gradually see).
Cataracts are the leading cause of blindness in the Third World: it explains nearly 40% of 37 million blind people around the world. It is therefore a problem of major public health in these countries, especially as the treatment is known and its application is limited only by the issue of cost. Contributing factors are malnutrition, dehydration, exposure to sunlight. It occurs in the subject while relatively young.
In the "rich", cataract is mainly observed in the elderly.
Types and causes
Cataracts are differentiated by their location: capsular or subcapsular, cortical, or nuclear equatorial or polar.
They are also differentiated by their causes:
* The vast majority of cataracts occurs naturally with age after 70 years, very gradually, without releasing cause particular. Some factors may have a role aggravate and hasten the onset of illness: overexposure to ultraviolet radiation, smoking, heredity, certain treatments such as prolonged corticosteroid therapy, diabetes and metabolic diseases, etc..
* Cataract hereditary, familial affection, whose early discovery in the very young child will bear the surgery faster or slower depending on the size of the opacity of the lens.
* The traumatic cataract development is usually rapid.
* Cataract secondary to serious diseases of the eye (uveitis old retinal detachment old).
Molecular origin suspected
The molecular recently discovered, for a patient through the examination of the membrane of the lens by an atomic force microscope (AFM). Two families of proteins are studied in the membranes of healthy and pathological crystalline: aquaporins and connexons. Aquaporins (proteins 5 nanometers) serve as channels for water. In pathological tissue, lack of connexons (assuring the passage of metabolites and ions) prevents the formation of channels to ensure communication between cells. These molecular changes explain the lack of grip, waste accumulation in cells and defects in transport of water, ions and metabolites in the affected tissue and cataract.
The only effective treatment for cataract is surgery. The operation was invented by the surgeon Franco in the sixteenth century. The procedure involves removing the cloudy lens and replace it with an artificial lens (intraocular implant) that takes place in the "envelope" of the lens (called the capsule) left partially in place during surgery (extraction Extra capsular). This intervention is now well developed and is typically under topical anesthesia or local. The operation is usually done for younger patients (below 30 years) under general anesthesia. The procedure takes about ten minutes, is painless, and vision returns quickly, subject to the normality of other ocular structures.
The operation is usually done on an outpatient basis, that is to say, without hospitalization, or only at very short hospitalization, as appropriate.
The implant may be focal, multiple a correct vision both near and far.
The most common complication of the intervention is secondary cataract may appear days to years after surgery. It corresponds to a clouding of the capsule. This cloudiness is treated by capsulotomy, mostly YAG laser. Impacts focused on the capsule will tear and go immediately normal vision. It also happens that one of the stitches on the cornea no longer be perfectly sealed. The surgeon then observes the sign of Seidel, reflecting the leakage of aqueous humor through the perforation. Care must be responsive and timely, the eye being exposed to great risk of infection.
Prudence dictates that we never dealt with both eyes during the same session.
In third world countries, intervention preference (for cost reasons) remains intra-capsular extraction of the lens, where the envelope (the capsule) is removed along with it. The results are worse than the extracapsular extraction.
Cataract surgery is the removal of the natural lens of the eye (also called "crystalline lens") that has developed an opacification, which is referred to as a cataract. Metabolic changes of the crystalline lens fibers over the time lead to the development of the cataract and loss of transparency, causing impairment or loss of vision. During cataract surgery, a patient's cloudy natural lens is removed and replaced with a synthetic lens to restore the lens's transparency.
Following surgical removal of the natural lens, an artificial intraocular lens implant is inserted (eye surgeons say that the lens is "implanted"). Cataract surgery is generally performed by an ophthalmologist (eye surgeon) in an ambulatory (rather than inpatient) setting, in a surgical center or hospital, using local anesthesia (either topical, peribulbar, or retrobulbar), usually causing little or no discomfort to the patient. Well over 90% of operations are successful in restoring useful vision, with a low complication rate. Day care, high volume, minimally invasive, small incision phacoemulsification with quick post-op recovery has become the standard of care in cataract surgery all over the world.
Read also Ophthalmology