The primary function of the crystalline lens is to the transmission of incident light and the focus on the retina. This requires that the lens is a transparent, condition, which is highly dependent on the regular holding of cells of the lens and a high degree of protein in the cytoplasm of the lens. The concentration of protein in the cells of the lens fibers, which is an extremely high refractive index significantly higher than in surrounding fluids and so allows the lens refracts incident light. Cataract occurs when the lens loses the transparency of the variance, or absorbing light, so that is at risk of Visual acuity. Cataracts may be due to genetic, metabolic, nutritional and environmental insults, or may be secondary to another disease of the eye, or system, such as diabetes or retinal degenerative diseases (see box). By far the most important risk factor is age; relating to the ageing of the cataract is the great majority of all turbidity and the problem of public health, which are all over the world. In developing countries where limited availability of equipment for surgical, relating to the ageing of the cataract is the leading cause of blindness. Because there is currently no effective-surgical therapy for cataract, the problem is expected to increase in size in the coming decades as the world population becomes progressively older.
Causes of turbidity
-The Ageing Of The
– Inheritance
-Metabolic Disorders, for example. Lowe syndrome, hypocalcaemia
-Diabetes
-The toxicity, for example, for drugs (steroids, amiodarone), chemical, metal ions
-Nutrition
-Natural dehydration
-Trauma
-Radiation
-Eye diseases, for example. glaucoma, uveitis, post-vitrectomy
– Systemic illness, for example. atopy, renal failure
Lens growth
Although the lens grows in the course of his life, none of the cells. Part of the cells are added to the lens, as time goes by, with those in the Centre are as old as the individual. The lens grows by adding regular fibres lens weight. The pace of growth is not uniform throughout the length of human life, and it seems that the maximum of the fruit of life. A Fetal lens mass increases by about 180 mg/year (the lens mass is 90 mg at birth), but the growth rate is declining significantly after birth and is 1.3 mg/year between 10 and 90 years old. Estimates of density, the diameter of the lens indicates that the protein content remained relatively constant at around 33% wet weight above the age range. The dimensions of the lens to change complex manner, as the lens is growing. In foetal youth lens is almost perfectly, but from birth in sagittal profile is an ellipse of Equatorial growth outstrips economic growth in the sagittal plane. On the birth of Equatorial lens diameter is about 6,5 mm, while the sagittal width is about 3 mm. in the age of 90 years it becomes about 10 mm in the Equatorial plane and 6 mm in the sagittal plane.
Classification of turbidity
It seems that the three main types of aging nuclear, cortical cataracts and rear subcapsular, which differ both in the place in which the opacity is initially and could be the basis for pathology. Many risk factors can be common for all three types of aging, cataracts, and although turbidity often begin as pure type, like ripe usually become mixed turbidity. The main types of cataracts in clinical practice are summarized in the box below. An objective classification schemes (see box) using photographic standards divide each main type into classes. These classes are based on the density and color (in the case of kernel), or according to the anatomical area of cataract (cortical Prior and posterior subcapsular area). One directly compare patient lens, as the slot the lamp with a photographic copy of the standard classes, as in the various classifications (clinical grading), or it may have one photo of the lens is to study and later class photos according to the classification scheme (photographic grading).
Types of cataracts
-Cortical
-Nuclear
-Rear subcapsular
-Mixed
-Mature, and hypermature
-Capsular
-Front subcapsular
– Retrodots
– Congenital and juvenile total or partial
-Traumatic
An objective classification schemes for turbidity
-The lens cover classification system II, and III (Sociedad Unión II and III)
Cataract classification system – Oxford
-Beaver Dam eye study
Of age related eye disease Study (AREDS)
According To Dr. Adam Adel
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