Cataract, what is it?
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The cataract is one of the most common eye disorders among people of old age. The human crystalline lens is in fact a "natural lens" which refracts light rays. The lens is located inside the eyeball between the iris and the vitreous body of the eye. In a young eye, the crystalline lens is transparent and elastic with a capacity to change shape instantly and provide focus which allows the eye to see well both at close and far distances. Cataract leads to partial or complete dimness of the crystalline lens, thus, only part of the light rays are able to enter the eye. This means that the affected person has poor vision and the images are unclear and blurred.
With years, the disorder develops, the sphere of dimness grows and vision deteriorates further. Failure to undergo cataract treatment in time may lead to complete blindness. This disorder may occur at any age. There is congenital cataract, traumatic cataract, complicated cataract, radiation cataract, and the disorder caused by general diseases of the organism. More often, the cataract is age-related and develops in people over 50.
According to the World Health Organization, there are about 17 million people worldwide with cataract, mainly at the age of over 60. At the age of 70-80, there are 260 men and 460 women with cataract for every 1,000 of the population. Over 80 years of age, it is practically everyone who suffers from the disorder. There are statistical data saying that 20 million people all over the world have been blinded by cataract.
Causes for cataract development
Among the factors stimulating the development of cataract, we may distinguish:
- genetic predisposition;
- facial traumas (chemical, mechanical, contusion);
- various eye diseases (including glaucoma, high myopia);
- endocrine disorders (metabolism failure, diabetes, avitaminosis);
- radiation, UHF, and ultraviolet irradiation;
- long-term administration of various medications;
- unfavorable ecological situation;
- toxic poisoning (naphthalene, dinitrophenol, thalium, mercury, ergot);
Symptoms of cataract
Ancient Greeks named this disorder kataraktes, which means ‘waterfall’. Cataract leads to blurred vision and the person sees objects as if through a screen of falling water or through a steamy glass. The development of the disease results in growing number of flashes of stripes, spots and haloes in the eyes around visible objects in bright light. There is also photophobia and doubling of images. It becomes difficult to read, write, or sew. As the cataract ‘matures’, the colour of the pupil changes from black to white.
Stages of age-related cataract
- The initial stages of cataract are manifested by dimness of the crystalline lens along the peripheral zone – outside the optical zone.
- A non-mature cataract is manifested by dimness advancing into the central optical zone. The crystalline lens dimness reduces vision acuity.
- A mature cataract displays dimness of the entire crystalline lens. The vision acuity is reduced to the level of light perception.
- An over mature cataract leads to the disintegration of the lens fibers, lens substance liquefies and the lens acquires a homogenous milky white colour.
How long does it take for a cataract to mature?
Ophthalmology observations indicate that there is a rapidly progressing maturity of the cataract in 12% of patients. It takes between 4 and 6 years from the beginning of the disorder to full dimness of the crystalline lens which requires urgent surgery.
About 15% of patients have a slowly progressing cataract which develops over a period of 10-15 years.
In 70% of cases, the development of the cataract takes 6-10 years. This requires an obligatory surgical treatment.
Diagnostics of cataract
The cataract is an insidious disorder, one which only a qualified specialist can identify whether you have it or not. Unfortunately, many patients begin paying attention to health of their eyes only after it starts to worry them.
The key method of diagnostic testing deals with examination of the fundus of the eye. Sometimes, this testing identifies definite problems. A more detailed examination is done with help of a so-called ‘slit lamp’ – biomicroscopy of the eye – which provides a directional illumination and magnified view. The light ray of the lamp is a slit-shaped.
The development of this technology was provoked by the discovery of Swedish physicist Gullstrand. It dates back to 1911, when he developed a device intended for lighting the fundus of the eye which later became known as a slit lamp. In order to light up the eye, the Swedish scientist used not the source of light but its reverse image projected into the zone of the slit diaphragm. The narrow beam of light rays created a clear cut contrast between the examined (illuminated) and dark sections of the eye. Later, specialists called it light activity. Biomicroscopy allows the ophthalmologist to discern all the elements of the eyeball and study in detail not only the external tissues but also the deeply imbedded tissue structures of the eye.
Along with the examination of the fundus with help of the slit lamp, the diagnostics of cataract also include methods which make it possible to estimate the power of the artificial crystalline lens (intra-ocular lens). This individual calculation of visual parameters is done with help of the unique “IOL-master” apparatus manufactured by the ZEISS company. This instrument makes it possible to simultaneously measure not only the length of the eye, curvature of the cornea, depth of the anterior chamber, and a state of the natural lens, but also to make an optimum calculation of the parameters of the artificial crystalline lens.
Treatment for cataract
Present day ophthalmology centers and clinics conduct treatment for the cataract using the method of ultrasonic phacoemulsification with implantation of an artificial intra-ocular lens. The operation deals with replacing the dimmed and cataract affected crystalline lens with an artificial intra-ocular lens. The local anaesthetic applied in the course of the operation is easily tolerated by patients of different ages and does not exert loads upon the cardio-vascular system.
Do not postpone treatment of the cataract under any circumstances!
At the late stages of the cataract, the swollen crystalline lens occupies the greater part of the anterior chamber of the eye, thus hampering the outflow of aqueous humor. This may lead to serious cataract complications, which is a secondary glaucoma. This is very dangerous since without proper surgical treatment, the vision is lost irreversibly.
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Recommended read: http://www.excimerclinic.ru