Cataract
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Cataract Microchapters |
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American Roentgen Ray Society Images of Cataract |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Kenneth J. Hoffer, M.D. [2], Clinical Professor of Ophthalmology, UCLA, St. Mary's Eye Center Associate Editor(s)-in-Chief: Rohan Bir Singh, M.B.B.S.[3]
Overview
A cataract is an opacification of the natural intraocular crystalline lens that transmits the light entering the eye onto the retina in the posterior part of the eye. The opacification leads to a decrease in vision and may lead to complete vision loss if left untreated for long. Cataracts are the leading cause of preventable blindness in the world . At present, there is no preventive intervention for the progression of cataracts. The modern cataract surgery, which is the removal of the opacified lens and implantation of a clear intraocular lens (IOL), is the only known and approved treatment for cataract. The cataract surgery involving removal of natural lens and implantation of IOL is the most effective procedure performed in ophthalmology with 3 million Americans choosing to have cataract surgery each year, and with a success rate of 97 percent or higher.
Historical Perspective
The word cataract, is derived from the Greek word υπόχυσις (kataráktēs) meaning the fall of water. The Latins have known it as "suffusio", which translates to an extravasation and coagulation of humors behind the iris; and the Arabs, call it white water . There is no mention of cataract in ancient Egyptian medical literature, except a similar disease, mentioned in the Ebers Papyrus (about 1525 B.C.).
The ancient Greeks believed that the lens was the part of the eye responsible for vision. It led to development of the emanation theory of vision. They believed that the optic nerves were hollow channels through which “visual spirits” were from the brain to meet visual rays from the outside world at the lens, in the center of the globe. The visual information would then flow back to the brain.
Around 30 AD, the Greek philosopher, Celsus drew the lens in the center of the globe, with an empty space called the locus vacuus anterior to it. This model about lens position and function persisted through the Middle Ages and into the Renaissance, as shown by the drawing of the Belgian anatomist Andreas Vesalius in 1543. The first accurate position of the crystalline lens was illustrated by the Italian anatomist Fabricius ab Aquapendente in 1600.
Swiss physician Felix Plater was the first to the challenge the emanation theory, and suggested that retina was the part of the eye responsible for sight.
Classification
Pathophysiology
Causes
Differentiating Cataract from other Diseases
Epidemiology and Demographics
Risk Factors
Screening
Natural History, Complications and Prognosis
Diagnosis
History and Symptoms | Physical Examination | Laboratory Findings | X Ray | CT | MRI | Other Imaging Findings | Other Diagnostic Studies
Treatment
Medical Therapy | Surgery | Primary Prevention | Secondary Prevention | Cost-Effectiveness of Therapy | Future or Investigational Therapies
Case Studies
Related Chapters
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