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Friday, October 25, 2019

Cataract: Definition, Symptoms, Causes and Diagnosis




Cataract: Definition, Symptoms and Diagnosis






Cataracts are currently the main cause of avoidable blindness, especially in developing countries, which represent around three quarters of blindness. Phacoemulsification is the primary method of performing cataract surgery in developed countries. However, in many developing countries involving most of the cataract blindness in the world today, phacoemulsification is not possible due to the cataract density involved and the high cost of the equipment

Cataract is used to define the opacifying condition of the lens of the eye. In other words, any opacity of the lens or its capsule, both congenital and acquired, is known as cataract. When lens transparency decreases enough to disturb vision, clinically significant cataract occurs. Since the target is an avascular structure, inflammatory disease cannot develop

The most common lens disease is the development of clouding of the lens fibers leading to the formation of different types of cataract. The decrease in lens transparency and the resulting cataract formation is generally the result of light scattering or absorption foci in the axial part of the lens. The term cataract is often used to indicate a change in the color of the target, as well as a decrease in its transparency


Cataract Definition 


The term cataract derives from the Latin cataract and from the Greek katarrakte which indicate a waterfall or a gate. Likewise, a cataract is a complete or partial opacification of sufficient severity, on or in the human lens or capsule, to impair vision

A cataract is a clouding or clouding of the normally transparent crystalline lens of the eye. This cloudiness can cause loss of vision and can lead to blindness (the objective is a transparent biconvex structure whose functions are: to maintain one's clarity, to refract light, to provide accommodation)


Cataract  Symptoms 



As cataracts develop slowly, symptoms are gradually detected. Symptoms in general, it affects only one eye (although cataracts can develop simultaneously in both eyes) and can include : 

• Gradual and painless start of blurred, dull or blurry vision

• Poor central vision

• Frequent changes in the prescription of glasses

• Changes in color vision

• Increased glare from the lights, in particular when approaching the headlights during night driving

• Improvement of "second vision" in near vision (reading glasses are no longer needed), but a reduction of distance vision

• Poor vision in sunlight

• In the pupil, is formeda milky whiteness as the cataract progresses


Cataract Causes 


• Most cataracts develop according to aging.This is when Protein structures change within the body, including the lens of the eye

• Inheritance

• Metabolic disorders, Lowe syndrome, hypocalcaemia

• Diabetes cataract is a common cause of visual impairment in patients with diabetes, acute diabetic cataract or cataract with snowflakes, consisting of bilateral and widespread changes in the sudden onset subcapsular lens, typically in young people with non-diabetes mellitus controlled

• Toxicity, induced by drugs (steroids, amiodarone), chemicals, metal ions

• Nutrition It has been more difficult to identify specific food deficiencies that lead to cataracts and supplements that protect against cataracts. Some studies have suggested that taking multivitamins, vitamin A, vitamin C, vitamin E, niacin, thiamine, riboflavin, beta carotene or increased protein may have a protective effect on cataract development

• Physical dehydration

• Traumatic cataract can be an early or late manifestation of eye trauma. Rupture of the lens capsule generally leads to rapid hydration of the lens cortex, causing the formation of a milky white cataract


The crystalline proteins can escape into the aqueous and vitreous and can cause uveitis and / or glaucoma

  • Radiation
  • Eye disease, glaucoma, uveitis, post-vitrectomy
  • Systemic disease, atopy, kidney failure


Cataract Diagnosis 



Both ophthalmologists and optometrists can detect and control cataract growth and prescribe prescription lenses to detect visual deficits. However, only an ophthalmologist can perform cataract removal

Cataracts are easily diagnosed by reporting symptoms:


• Snellen's visual acuity for near and far vision must be assessed with appropriate glasses

• Non-Snellen visual acuity Some patients complain of poor visual function despite Snellen's good visual acuity. Cataracts can lead to a reduction in the perception of contrast resulting in visual dysfunction. Especially subcapsular and posterior cortical cataract can cause debilitating glare

• Lens and pupil examination When using a bright flashlight, lens opacities do not affect direct and agreed pupillary responses. But in the dim light test, the answer may be less pronounced when the eye is illuminated by dense cataract

• Direct ophthalmoscopy In direct ophthalmoscopy, nuclear cataracts are visible as lenses inside a lens when viewed against the red glow of the background

• Slit lamp biomicroscopy, as previously described, allows a detailed examination of the anterior segment of the eye

• Refraction and retinoscopy The patient with nuclear cataract shows an index myopia in the early stages. It can be detected by routine refractive examination. Patients can be corrected for years with stronger close-range glasses and standard reading glasses for near vision

• Ultrasonography A-scan and B-scan ultrasound are standard methods for accurately measuring the thickness and position of lens opacities. The B-scan ultrasound is particularly useful for evaluating abnormalities of the posterior segment of the eye with a very dense cataract. the use of ultrasound help  to determine the anatomical state of the eye behind the lens


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