Summary   Summary
Featured Diseases & Conditions
Health Awareness Articles
Articles
Symptom Checker

Symptom Checker
Just click on a body part, choose your symptom and search through a world of health information.

 

Search Diseases

Search Disease

Cataracts


Overview :

The human eye has several parts. The outer layer of the eyeball consists of a transparent dome-shaped cornea and an opaque, white sclera. The cornea and sclera help protect the eye. The next layer includes the iris, pupil, and ciliary body. The iris is the colored part of the eye and the pupil is the small dark round hole in the middle of the iris. The pupil and iris allow light into the eye. The ciliary body contains muscles that help in the eye's focusing ability. The lens lies behind the pupil and iris. It is covered by a cellophane-like capsule. The lens is normally transparent, elliptical in shape, and somewhat elastic. This elasticity allows the lens to focus on both near and far objects. The lens is attached to the ciliary body by fibers (zonules of Zinn). Muscles in the ciliary body act on the zonules, which then change the shape of the lens. This process is called accommodation—the lens focuses images to help make vision clear. As people age, the lens hardens and changes shape less easily. As a result, the accommodation process becomes more difficult, making it harder to see things up close. This generally occurs around the age of 40 and continues until about age 65. The condition is called presbyopia. It is a normal condition of aging, generally resulting in the need for reading glasses.

The lens is made up of approximately 35% protein and 65% water. As people age, degenerative changes in the lens's proteins occur. Changes in the proteins, water content, enzymes, and other chemicals are some of the reasons for the formation of a cataract.

The major areas of the lens are the nucleus, the cortex, and the capsule. The nucleus is in the center of the lens, the cortex surrounds the nucleus, and the capsule is the outer layer. Opacities can occur in any area of the lens. Cataracts, then, can be classified according to location (nuclear, cortical, or posterior subcapular cataracts). The density and location of the cataract determine the amount of vision affected. If the cataract forms in the area of the lens directly behind the pupil, vision may be significantly impaired. A cataract that occurs on the outer edges or side of the lens will create less of a visual problem.

Cataracts in the elderly are so common that they are thought to be a normal part of the aging process. Between the ages of 52 and 64, there is a 50% chance of having a cataract, while at least 70% of those 70 and older are affected. In 2004, it was revealed that blacks are twice as likely to develop cataracts as whites. Cataracts associated with aging (senile or age-related cataracts) most often occur in both eyes, with each cataract progressing at a different rate. Initially, cataracts may not affect vision. If the cataract remains small or at the periphery of the lens, the visual changes may be minor.

Cataracts that occur in people other than the elderly are much less common. Congenital cataracts occur very rarely in newborns. Genetic defects or an infection or disease in the mother during pregnancy are among the causes of congenital cataracts. Traumatic cataracts may develop after a foreign body or trauma injures the lens or eye. Systemic illnesses, such as diabetes, may result in cataracts. Cataracts can also occur secondary to other eye diseases—for example, an inflammation of the inner layer of the eye (uveitis) or glaucoma. Such cataracts are called complicated cataracts. Toxic cataracts result from chemical toxicity, such as steroid use. Cataracts can also result from exposure to the sun's ultraviolet (UV) rays.




 Image Gallary
 
Search for information related to Health and wellness
Health Centers
Cardiology and HeartMen's HealthWomen's HealthMother + ChildDiabetesStressInfectious DiseaseSkinEyeCancerStop SmokingWeight ManagementSexual HealthBlood Pressure ManagementAsthmaPregnancy and Child BirthAllergyHair LossDengueCold and FluSore ThroatADHDDental & Oral HealthHigh CholesterolDepressionPolioBreast CancerFood PoisonSnoringConjunctivitisCervical CancerJaundiceGeneral HealthMigraine / HeadacheThyroidBlood SugarProstate CancerKidney DiseaseAnxietyArthritisAutismBipolar DisorderCOPDCaregivingCrohn's DiseaseEpilepsyErectile DysfunctionHealthy AgingIncontinenceMeningitisMenopauseMultiple SclerosisOsteoporosisPain ManagementParkinson's DiseaseRelationshipsSleep ManagementStomach & DigestiveOsteoarthritisPertussisOveractive BladderRheumatoid ArthritisTonsils
Search for information related to Health and wellness
 
Health Pages
blood pressure cancer cholesterol test diabetes diets erectile dysfunction hair loss health health articles healthy living heart diseases high cholesterol pregnancy reduce weight vagina weight wellness health plan sexual problems lower cholesterol heart attack women health asthma weight loss anxiety back problems disease symptoms immunization for children indian home remedies indian recipes Manage weight pathology tests stress intelligence test triglycerides exercise low cholesterol salma hayek breast feeding pros and cons on abortion perfect breasts symptoms of esophageal cancer tooth abcess lower high cholesterol abortion activists triglycerides and alcohol consumption cyclical breast pain cholesterol lipid healthy eating blood pressure symptoms