Cataract
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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 current word cataract, which means both an opacity of the lens and a torrent of water, comes from the Greek word υπόχυσις (kataráktēs) meaning the fall of water. The Latins called it suffusio, an extravasation and coagulation of humors behind the iris; and the Arabas, white water (Ascaso & Cristóbal, 2001). The old Egyptian name for the lens is not yet known and the medical literature does not let us conclude that old Egyptians were able to diagnose cataracts (Ghalioungui, 1973). The only possible reference to cataract is the ch.t disease mentioned in the Ebers Papyrus (about 1525 B.C.). Ebbel translated the ch.t disease as cataract (Ebbel, 1937). However, other distinguished linguistists interpreted it as a discharge or accumulation of water in the eyes (Hirschberg, 1899; Deines et al., 1958;Andersen, 1997). According to Ebers Papyrus, the old Egyptians tried to treat cases of ch.t disease by eye ointments and magic spells. It is hardly believable that such remedies had any effect on the cataract, since the extraction of the lens is the only effective measure. The ancient Greeks and Romans believed that the lens was the part of the eye responsible for the faculty of seeing. They theorized that the optic nerves were hollow channels through which “visual spirits” traveled from the brain to meet visual rays from the outside world at the lens, which theythought was located in the center of the globe. The visual information would then flow back to the brain. This concept was known as the emanation theory of vision. Celsus (25 BC–AD 50) drew thelens in the center of the globe, with an empty space called the locus vacuus anterior to it, in AD 30 These erroneous ideas about lens position and function persisted through the Middle Ages and into theRenaissance, as shown by the drawing of the Belgian anatomist Andreas Vesalius in 1543 ( Fig I-2). The true position of the crystalline lens was illustrated by the Italian anatomist Fabricius ab Aquapendente in 1600(Fig I-3) , and the Swiss physician Felix Plater (1536–1614) was the first to postulate that the retina, not thelens, was the part of the eye responsible for sight.Today, many areas of lens physiology and biochemistry are still subjects of active research. No medical treatment, for example, can yet prevent theformation or progression of cataract in the lens of theotherwise healthy adult eye, and theories about cataract formation and innovative forms of management continueto be controversial. Although various risk factors forcataract development have been identified (discussed in Chapter 1), data to develop guidelines for reducing the risk of cataract remain inconclusive.The prevalence of lens disorders and continuing developments in their management make the basic and clinical science of this structure a vital component of ophthalmology training. The goal of Section 11 is to provide a curriculum for the study of the structure and function of the normal lens, the features of diseases involving the lens, and the surgical management of cataract.
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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