Ординатура / Офтальмология / Английские материалы / The Encyclopedia of Blindness and Vision Impairment_Sardegna, Shelly, Shelly, Steidl_2002

The posterior chamber is the site of surgery for posterior intraocular lens implantations. As a part of CATARACT surgery, a plastic lens is often placed either in front of, or behind, the iris to replace the portion of natural lens lost to surgery. Posterior lens implantation places the artiÞcial lens behind the iris.

Posterior is also a term used to describe the back portion of the eye behind the lens. This area is Þlled with the vitreous, a clear gel-like material that makes up 80 percent of the volume of the eye. The vitreous gives volume to the eye and supports the other organs within the globe.

The expanded deÞnition or boundaries of the posterior area may include the RETINA, OPTIC NERVE, and portions of the CHOROID and SCLERA, which are positioned in the back of the eye. This area may be injected with antibiotics or other medications in the treatment of disease or infection. It may be the site of surgery as in RETINAL DETACHMENT operations, or vitrectomies. In retinal detachment surgery, the retina is reattached to the epithelial layer next to the choroid. During vitrectomy, the chamber behind the lens is drained of diseased vitreous gel and Þlled with a sterile saline solution.

The posterior section behind the lens may be subject to ßoaters, bits of debris or blood in the vitreous. Light passing through the vitreous casts shadows of the debris onto the retina, causing images of the debris to ßoat through the Þeld of vision. Floaters appear in normal vision and are not considered as a symptom of disease unless they appear suddenly or in large numbers.

potential acuity meter (PAM) A slit-lamp attachment used to assess the potential, usable vision of those with cataractous lenses or corneal opacities.

The PAM uses a prism system and self-illumina- tion to project a small SNELLEN CHART through a clear section of the cornea or lens and onto the retina of the person being examined. In by-passing the opacities, the examiner can efÞciently use the Snellen chart to measure visual acuity.

presbyopia Aging of the eyes. As the eye ages, the lens deteriorates and loses the ability to focus

near objects. The Þrst symptoms usually arise after 40 years of age and include difÞculty in reading or doing close work.

Prescriptive convex lenses in reading glasses or bifocals may correct the problem. In addition, a Texas-based company called Presby Corp. has developed and is marketing a surgical technique called Surgical Reversal of Presbyopia. The procedure uses a tiny device called a scleral expansion band to expand the diameter of the sclera. This causes the distance between the scleral and the lens to increase, restoring the effective working distance of the muscle, as in a younger eye. The company is conducting investigational clinical trials at six universities to test the procedure.

President’s Committee on Employment of People with Disabilities See

PLOYMENT POLICY.

Prevent Blindness America The oldest national voluntary health organization working to prevent blindness. Founded in 1908, it has been formerly known as the National Committee for the Prevention of Blindness, the National Society for the Prevention of Blindness, and the National Society to Prevent Blindness. The goal of the organization is to preserve sight and prevent blindness through community-service programs, public and professional education, and research.

Prevent Blindness America activities include preschool vision testing, distributing a family home eye test called ÒHowÕs Your Vision?,Ó local glaucoma screening and educational programs, and promoting industrial and recreational eye-safety programs. The organization also promotes cooperative public and educational programs with governmental and voluntary health and social-service agencies, and sponsors the National Center for Sight, a toll-free number for eye health and safety information. The line is open from 8:30 A.M. to 5 P.M. Central time, and can be reached at 800-331- 2020. Prevent Blindness America also maintains a website with extensive information and links to other eye careÐrelated sites. In addition, it sponsors research projects to Þnd the causes and treatments for eye diseases and disorders.

Publications include Insight, an annual report, and a wide range of pamphlets and brochures dealing with eye safety, home-vision screening, eye health, and industrial and recreational eye safety. The organization also publishes Prevent Blindness News, a 12-page newsletter printed three times a year.

Contact:

Prevent Blindness America 500 E. Remington Road Schaumburg, IL 60173 800-331-2020 www.preventblindness.org

prevention of blindness According to the Prevent Blindness America there are currently more than half a million legally blind people in the United States, and more than 50,000 people become blind each year. Prevent Blindness America estimates that 50 percent of blindness can be prevented with current medical knowledge and techniques and that 90 percent of all accidental eye damage can be averted with proper eye-safety practices and appropriate eyewear.

The leading causes of blindness in the United States are GLAUCOMA, MACULAR DISEASE, CATARACT,

OPTIC NERVE ATROPHY, DIABETIC RETINOPATHY, and RE-

TINITIS PIGMENTOSA. These causes represent an estimated 51 percent of blindness cases. The leading causes of new cases of blindness are macular degeneration, glaucoma, diabetic retinopathy, and cataract.

There are approximately 11.4 million visually impaired persons in the United States, those who have serious vision problems but who cannot be classiÞed as legally blind. Of this group, 1.4 million have severe vision impairments that hinder them from reading ordinary newsprint even with the aid of corrective lenses.

The most common causes of vision impairment are cataract, INJURIES, glaucoma, and CONGENITAL DISORDERS. Cataract is responsible for up to onethird of all new cases of vision impairment. Injuryrelated vision impairments number close to nearly 1 million, with an estimated 40,000 new cases caused by injury each year.

The best defense against blindness or vision impairment due to disease or disorder is an annual

or biannual eye examination after the age of 35. Many diseases are easiest to control and have the best success records when diagnosed and treated in the early stages.

Injury-related vision impairments may be prevented by wearing protective eye wear and improving eye-safety practices, such as improving contact-lens hygiene and overwear time and wearing seat belts while traveling in the car. The materials and products most commonly associated with injuries to the eyes are metal fragments, contact lenses, motor vehicles, and chemicals.

Work-related accidents account for at least 61,000 eye injuries each year. Prevention of blindness due to occupational hazards or injuries is closely monitored by the Occupational Safety and Health Administration (OSHA), which enforces occupational health and safety standards, and the American National Standards Institute, which speciÞes manufacturing standards for protective eyewear.

Work-related injuries may be prevented by the consistent use of appropriate eye-protection gear. A recent survey by the Bureau of Labor Statistics showed that three out of Þve workers who suffered an eye injury wore no eye protection. Of those who did, 40 percent wore the wrong kind. Protective eye-safety wear includes safety goggles or glasses, side shields, eye-cup side shields, ventilated goggles, face shields, and helmets. Safety glasses or goggles are made of impact-resistant glass, plastic, or polycarbonate prescription or non-prescription lenses. The glasses frames are reinforced more strongly than normal types and are heat resistant.

Side shields that attach to, or that are part of, the safety goggle frame protect the eyes from ßying particles or objects from the front and sides of the wearer. Eye-cup side shields protect the wearer from ßying objects from the front, side, top, and bottom.

Goggles Þtted with regular or indirect ventilation protect the wearer from chemical splashes, dust, sparks, and ßying particles. Face shields protect from splashes, heat, glare, and ßying objects and must be worn over safety goggles or glasses. Welding helmets with appropriate Þlter plates or lenses protect the wearer from splashes of molten metal, sparks and the intense heat and light of

welding. The helmets are worn over safety glasses or goggles.

Sports-related injuries account for more than 40,000 emergency room eye treatments annually. Sports with the highest injury frequencies are baseball, basketball, racquet sports, and football. More than 90 percent of all eye injuries and resulting vision impairments may be prevented in sportrelated activities by wearing safety eyeguards or industrial-quality safety glasses.

Over 420,000 persons in the United States have lost some sight due to home eye injuries, nearly 45 percent of all injuries. Home injuries are usually product related and are due generally to home structure or construction materials such as nails and lumber, home-maintenance products such as glues and bleaches, personal-use products including contact lenses and sun lamps, and home shop equipment such as batteries and manual tools. Household products cause more than 32,000 serious injuries each year.

Home eye injuries can be prevented by wearing eye protection such as safety glasses (ANSI Z-87) when using hazardous materials or working with tools. Safety goggles should be worn as a protection against battery fragments or acid when jump-start- ing a car.

Ultraviolet absorbing sunglasses should be worn in sunlight, due to evidence that UV rays can damage the eyes and contribute to the development of various disorders, including macular degeneration and cataracts.

Public education programs organized by nonproÞt associations, state departments of education, public health-care providers, and civic and service groups serve to prevent blindness by alerting and educating the public about eye care, eye safety, and eye diseases. Many such organizations perform free eye examinations, provide training and education programs for professionals in the eye-care Þeld, support research into eye diseases, and work for legislation to enforce and extend existing laws for eye protection and safety. (See VITAMINS, WORLD BLINDNESS.)

Krames Communications. A Guide to Eye Safety. Daly City, California: KC, 1987.

Prevent Blindness America. ÒSafety.Ó www.preventblindness.org, 2000.

Prevent Blindness America. ÒFacts and Figures.Ó

www.preventblindness.org, 2000.

prisms Prisms are inexpensive optical additions to prescriptive lenses that maximize use of remaining vision. They are used to improve ocular conditions such as NYSTAGMUS, DIPLOPIA, macular disease, or peripheral-Þeld defects.

Prisms are horizontally incorporated into frames for prescriptive lenses or noncorrective spectacles to treat nystagmus, an uncontrollable jerking of the eyes that impairs focusing on an object. The prisms may relieve symptomatic headache and improve acuity and stabilization of vision.

Vertically applied prisms are used to treat diplopia, or double vision, due to retinal surgery. The prisms compensate for the impaired abilities of the extraocular muscles.

Those with macular disease may be helped by prisms. If the MACULA, or central section of sight, is impaired or destroyed, prisms can be placed to move the image from the FOVEA (central macular region) to an area outside the fovea that is usable.

Prisms such as the Fresnel prism are used for peripheral-field (side vision) defects. They are incorporated into prescription lenses or pressed onto noncorrective spectacles in sections above and below or to the sides of the usable central visual Þeld. By moving the eyes or the head slightly, the user can see through the prisms into the restricted Þeld.

progressive addition lenses Seamless, multifocal lenses that allow the wearer a smooth transition from the distance portion of the lens into the reading portion. No line is visible, either to the wearer or anyone else. The power of a progressive addition lens gradually increases as the wearer looks from the distance portion to the reading portion, creating an appropriate lens power for every distance. A disadvantage of these lenses is that the sides tend to become distorted, making side vision appear to be wavy. Technology for creating these lenses, which Þrst appeared in the late 1970s, continues to improve, however, and wearers Þnd the distortion to be less troublesome as they get accustomed to the lenses.

proliferative retinopathy A retinal disorder that occurs as a complication of DIABETES. It is a serious disease that can result in permanent vision impairment or blindness.

Proliferative retinopathy is one of three types of DIABETIC RETINOPATHY, which also include exudative, or background retinopathy, and preproliferative retinopathy. Diabetic retinopathy is a circulatory disorder that causes the blood vessels that nourish the RETINA, a light-sensitive inner lining in the back layer of the eye, to weaken, disintegrate or become blocked. The vessels may leak ßuid, bleed, grow unnaturally, bulge, or stop functioning completely.

Exudative retinopathy is a Þrst stage of diabetic retinopathy in which small hemorrhages occur from the retinal vessels. Hard exudates form rings around the damaged vessels. This condition rarely affects vision and may last indeÞnitely or progress to a more serious stage. The preproliferative stage is marked by an increasing number of hemorrhages, dilation of the retinal vein, and the occurrence of soft exudates. Preproliferative retinopathy is a serious condition that may rapidly progress to the proliferative stage.

Proliferative retinopathy involves neovascularization or development of abnormal blood vessels within the retina and VITREOUS. The vessels develop as a result of ischemia, tissue anemia due to an obstruction to the ßow of blood. The new, weak vessels grow between the vitreous and the retina, near the OPTIC DISC. They leak and cause retinal and vitreal hemorrhages. The vitreous may shrink and pull the vessels with it, causing hemorrhaging, Þbrous-tissue development, retinal tears, retinal detachment, and secondary glaucoma. At Þrst, a person with proliferative retinopathy may notice few symptoms of the disorder. As the condition progresses, ßoaters may be seen, and vision may become blurred or lost.

Proliferative retinopathy is diagnosed by an eye examination. FLUORESCEIN ANGIOGRAPHY may be used to aid diagnosis and locate areas of greatest proliferation. During this procedure, ßuorescein dye is injected into a vein in the arm and monitored as it ßows through the retina. B-SCAN ultrasonography, or sonar vision, may be applied if the

transparent tissues have become opaque due to hemorrhage.

Treatment consists of photocoagulation or laser therapy. Originally, the treatment involved areas of the retina in which the neovascularization had occurred. Now, the photocoagulation is applied extensively in the retina in a method called panretinal photocoagulation (PRP). During this treatment, over 1,000 laser burns are placed on the retina, excluding the macular area. These areas are destroyed, allowing the limited blood supply to reach and nourish the MACULA, or area of sharpest sight.

Vitrectomy may be necessary in cases of extreme vitreal hemorrhage or traction detachment. A specialized instrument is inserted into the vitreous where it breaks down blood deposits and scar tissue. It then removes the matter and the diseased vitreous ßuid by suction. Simultaneously, a sterile saline ßuid is injected to replace the vitreous ßuid. Approximately two thirds of those who undergo vitrectomy gain improved vision.

Proliferative retinopathy may regress spontaneously. In cases of progressive proliferative retinopathy, early treatment of the ocular condition and the underlying diabetes may prevent or limit vision loss.

Galloway, N. R. Common Eye Diseases and Their Management. Berlin: Springer-Verlag, 1985.

Rhoade, Stephen J., and Stephen P. Ginsberg. Ophthalmic Technology. New York: Raven Press, 1987.

Vaughn, Daniel, and Taylor Asbury. General Ophthalmology. Los Altos, California: Lange Medical Publications, 1977.

proptosis See EXOPHTHALMOS.

prosthesis A prosthetic or artiÞcial eye is used to replace an eye that has been enucleated, or surgically removed. Prosthetic eyes have been in existence for centuries. Ancient Egyptian cultures fashioned wax, plasteror precious-stone eyes to adorn their dead.

Roman surgeon priests made artiÞcial eyes for the living out of wood, shells, bone, ivory, stone, and precious metals. In the 16th century, Venetians developed the Þrst glass eyes, but the precursor of

the modern type of prosthetic was developed in the 17th century by French surgeons.

Before World War II, most prosthetic eyes were manufactured of glass in Germany and exported to other countries. After the war, plastic prosthetics were invented and manufactured throughout the world. Modern prosthetic eyes are made from glass or plastic by ocularists. They are custom shaped to match the eye socket of the individual and the coloring of the natural eye. Prosthetic eyes are generally nondistinguishable from natural eyes.

Two or more days after enucleation the eye socket is Þtted with a plastic shell that will cradle the prosthesis. Three or four weeks later, the prosthetic eye is Þtted. The eye is attached to the remaining extrinsic muscles in the orbit to ensure natural movement.

The prosthetic eye is worn constantly to prevent contraction of the eye socket. It is cleansed daily and may be lubricated with drops for this purpose. A slight mucous discharge is a normal characteristic of prosthesis wearers, but profuse discharge could indicate an infection.

Infection often stems from roughening of the prosthesis. The prosthesis should be polished once or twice a year to buff out scratches and reduce irritation, and should be checked for wear by a specialist at regular intervals. Most plastic prosthetic eyes last Þve years on average.

pterygium See CONJUNCTIVA.

ptosis A sagging of the upper eyelid. It may be congenital or acquired and can affect one or both eyes. The disorder may appear congenitally in children or in adults due to aging, nerve palsy, inßammation, styes, tumors, cysts, MYASTHENIA GRAV- IS, oculomotor palsy, HornerÕs syndrome, or use of guanethidine eyedrops.

Mild ptosis that does not affect vision may require no treatment. Severe forms of the condition may affect vision by obstructing the pupil or may be cosmetically unattractive. After careful diagnosis as to the cause, ptosis may be corrected surgically in some congenital, nerve palsy, or age-related cases.

Surgery may be performed on children of three or four years of age or younger if the ptosis is uni-

lateral and causing AMBLYOPIA. The surgery may be performed under local anesthetic for adults and general anesthetic for children. The type of surgical procedure used depends on the severity and underlying cause of each case.

Three surgical procedures are most commonly used. The Fansanella-Servat involves the removal of a portion of the lid from the inside. The outer skin is not incised. The shortened lid is lifted off the eye. This procedure is used to treat mild cases of ptosis. The levator resection is used to treat moderate cases. During this procedure several incisions are made in the lid. A sling is placed inside the lid to permanently lift it. The frontalis suspension is reserved for severe cases of ptosis. A section of the muscle that raises the eyelid is removed. The surface skin of the eyelid is usually involved in the incision. The shortened muscle keeps the lid elevated. Complications from eyelid surgery may include infection, bleeding, scarring, and corneal drying. Overand undercorrections may occur.

Treatment of other forms of ptosis involves treating the underlying cause. Neostigmine may be prescribed in cases of myasthenia gravis. When surgery is contraindicated, special spectacles with an attached crutch to raise the eyelid may be prescribed.

pupil The small opening centered in the IRIS of the eye. It allows light to pass into the eye. The pupil can change size to accommodate different light extremes. The iris, or colored part of the eye, regulates the size of the pupil by using adjacent dilator and sphincter muscles to open and close it. In bright light, the pupil constricts to screen out excess light. In low light, it opens up to allow the maximum amount of light to enter the eye.

The pupil may open wider in response to a stimulus other than light. Emotions of fear, excitement and delight, and loud noises may dilate the pupil. Drugs may artiÞcially dilate or constrict the pupil. Cycloplegic drops dilate the pupil. Different types such as tropicamide, cyclopentolate, or atropine are effective from three hours to seven days. The pupil is dilated to examine the back of the eye and to treat conditions such as IRITIS and CYCLITIS. Occasionally, dilation of the pupils can bring about an

attack of GLAUCOMA in eyes with narrow ANTERIOR CHAMBERS.

Meiotic drops constrict the pupil. Pilocarpine, ecothiopate, or phospholine iodide may constrict the pupil from 4 to 12 hours. The pupils are constricted to reduce intraocular pressure.

The pupil is black because the inside of the eye showing through it is dark. Any change in the color

or shape of the pupil may indicate a disorder within the eye or the body. A light-colored pupil, called leukokoria, may indicate the presence of a tumor.

A constricted or misshapen pupil may be evidence of iritis. An enlarged pupil may indicate glaucoma or increased intracranial pressure. Pupils of unequal size may also be the result of anisocoria, a congenital defect.

radial keratotomy (RK) A type of CORNEA surgery developed in the Soviet Union by Dr. Syvatoslav Fyodorov. The surgery is designed to improve myopia (nearsightedness). The ultimate goal of the surgery is to restore the patientÕs vision to 20/20 without the use of contact lenses or eyeglasses. The words radial keratotomy refer to the radial cuts or incisions made on the cornea during surgery.

Those with mild myopia can expect the best results from radial keratotomy. Possible candidates must require glasses or contact lenses to correct their vision. The best results are for those with a refraction between -2.00 to -4.00 diopters and a visual acuity level of 20/80 to 20/200. Those with high myopia (-5.00 or greater) will not achieve the same results.

Although prospective RK patients must be mildly myopic, people with very slight myopia are discouraged from undergoing surgery for such minimal correction. Those with corneal disorders, GLAUCOMA or pre-glaucomatous conditions, lenticular astigmatism, or other eye disorders are also often not considered good candidates for this surgery.

The presurgical examination involves an external examination of the eye, a vision acuity test, and a refraction test. Additional tests may include corneascope photographs, a slit-lamp examination, intraocular-pressure testing, motility studies, and cornea measurement and depth testing.

Approximately one hour before surgery, the patient is treated with two or more sets of eye drops to dilate and anesthetize the eye. Many surgeons also administer an antibiotic such as gentamicin sulfate.

In the operating room, the surgeon takes a number of exact readings and measurements of the

R

eye to determine the surgical plan. The cornea is stamped with a trephine, a cookie-cutter-like instrument that marks an incision pattern that the surgeon uses as a guide. The pattern includes a center circular clear zone and a variable number of incision lines radiating out from the clear zone. The surgeon uses a diamond blade to cut from the clear zone circle outward. The procedure ßattens or shortens the cornea, to produce better refraction and improved vision.

The surgery is done on an outpatient basis (without overnight hospitalization) and generally requires 30 minutes per eye. The eye is covered with a patch for 24 hours, and eye drops such as pilocarpine hydrochloride are used for a week.

After surgery the patient may experience pain, sensitivity to light, tearing, decrease or ßuctuation of visual acuity, overor undercorrection, and astigmatism. Patients may achieve from 20/20 vision to 20/200 vision, or experience no improvement at all.

Studies indicate that radial keratotomy improves vision in the majority of cases. However, the procedure remains a controversial one and the prospective candidate for RK is encouraged to research the procedure, its risks and beneÞts and the surgeon involved to develop a reasonable expectation.

Waring, A. O., et al. ÒResults of the Prospective Evaluation of Radial Keratotomy (PERK) Study on Year After Surgery.Ó Ophthalmology, vol. 92, no. 2 (February 1985): 177.

radiation burns Burns caused by light. Ocular radiation burns can be caused by ultraviolet rays, infrared rays, X rays, microwaves, laser beams, and gamma rays.

Burns due to ultraviolet rays include SNOW BLINDNESS, weldersÕ ßash, and sun-lamp injuries. Ultraviolet waves do not penetrate the globe and therefore deliver a burn to the CORNEA, or clear, outermost covering of the eye. Symptoms of these burns are usually delayed two to nine hours and include extreme pain, a sensation of sand in the eyes, and severe light sensitivity. The burns heal themselves within two to three days but antibiotics or steroid drops may be prescribed. Ultraviolet burns can be prevented by wearing protective eyeglasses or goggles.

Eclipse blindness is an ultraviolet burn caused by watching the sun during an eclipse. Although the ultraviolet rays of the sun do not enter the globe, the heat generated within the eye during prolonged exposure to these rays produces a burn to the MACULA. The macula is the area of clearest sight within the RETINA, the light-sensitive layer at the back of the eye. The damage to the macula from an eclipse burn is irreversible and causes loss of central vision. An eclipse cannot be safely viewed directly. Sunglasses, photographic film, or film negatives afford no protection to the eyes. An eclipse may be safely viewed indirectly by observing the image of the sun projected onto a flat surface through a small hole in a piece of paper.

Infrared rays can penetrate the eye and may cause CATARACTS. In the past, ocular infrared burns were found among steel workers and glass blowers. The adoption of safety goggles and eyeshields has virtually eliminated the problem.

X rays may produce cataracts in threshold doses of approximately 1,000 rad but may vary with exposure times. Simple dental or diagnostic X rays will not endanger the eyes. X rays that are used therapeutically to treat lesions near the eyes should be given only when the eyes are appropriately shielded.

Microwaves may cause cataracts but only when the eye is in the direct line of the beam. According to current knowledge, microwave ovens constitute no threat to vision.

LASERS are intense beams of light that can enter the globe of the eye. They are used therapeutically in ophthalmology to heal hemorrhages in the retina. The beam is focused directly onto the point

of therapy that is exposed to the light for a speciÞc amount of time. Industrial lasers can produce retinal burns when viewed directly or by reßection off other objects.

Gamma rays can produce cataracts and loss of vision. The rays released by atomic bomb explosions resulted in mass amounts of cataract cases following the bombings of Hiroshima and Nagasaki during World War II.

radio information services Radio channels and programs that provide news and information on community events. Many services read sections or complete issues of local newspapers and offer information of interest to visually impaired listeners.

Radio services may be broadcast on open, freely accessible channels or on closed channels that require a reception box available to the user through the broadcasting station. State radio information services are often titled Radio Reading Service, Radio Talking Book, or Radio Information Service. (See Appendix for listing by state.) Local cable television stations may provide similar services.

Television descriptive services such as Descriptive Video Service (DVS) and Washington Ear provide narration describing various visual features of dramatic television programs. During the program, the narrator supplies details of the costuming, lighting and physical actions taking place. The service uses a separate channel accessible through an adapter that is compatible with standard television and video cassette recorders with stereo capabilities.

Contact:

Descriptive Video Service, WGBH-TV 125 Western Avenue

Boston, MA 02134 617-300-5400 (ph) 617-300-1026 (fax) http:\\main.wgbh.org

The Metropolitan Washington Ear, Inc. 35 University Boulevard East

Silver Spring, MD 20901 301-681-6636 (ph) 301-681-5227 (fax) www.washear.org

Rail Passenger Service Act The Rail Passenger Service Act, as amended by the Amtrak Improvement Act of 1973, founded the National Railroad Passenger corporation. The corporation must ensure that no elderly or disabled person is denied transit on any intercity passenger train operated in connection with the corporation.

The corporation was instructed to renovate existing facilities and equipment to make them accessible to elderly or disabled persons, to ensure that new facilities or equipment comply with accessibility standards, to provide special employee training dealing with traveling needs or concerns of the elderly and disabled, and to assist elderly and disabled passengers in the terminal and as they board and alight the trains.

Amtrak was instructed in 1990 to make access improvements at some stations that it shared with a commuter authority. Those instructions were a result of the Americans with Disabilities Act of 1990. They were noted in AmtrakÕs 1997 Reform and Accountability Act.

U.S. Department of Education. Summary of Existing Legislation Affecting Persons with Disabilities. Washington, D.C.: USDE, 1988.

Amtrak Reform Council. ÒThe Amtrak Reform and Accountability Act of 1997.Ó www.amtrakreformcouncil.gov, 1997.

Raised Dot Computing (RDC) See DUXBURY

SYSTEMS, INC.

raised-line drawing kit A tactual aid used to make pictures or graphs. It consists of a board covered with a soft underlay of rubber. The user places a sheet of acetate over the board and draws on it, creating raised lines and an embossed picture.

Randolph-Sheppard Act The Randolph-Shep- pard Act of 1938 established an employmentopportunities program in which blind individuals could operate vending facilities on federal property. Amendments to the act, legislated in 1974, extended its scope to include federal property operated by all federal agencies or departments and added operational guidelines to be authorized by state licensing agencies.

The act amendments outlined procedures and regulations to ensure fair treatment between blind vendors, the licensing agencies, and the federal government, and established greater control and participation by the Rehabilitation Services Administration. In cases in which vending machines directly compete with blind vendors, the amendments allowed the income from the machines to accrue to the vendor or to be used by the state licensing agency as a sick fund or vacation/ retirement fund. (See BUSINESS ENTERPRISE PRO- GRAM.)

U.S. Department of Education. Summary of Existing Legislation Affecting Persons with Disabilities. Washington, D.C.: USDE, 1988.

reading machines Machines that ÒreadÓ printed material aloud via a voice synthesizer. They are used by visually impaired and blind persons who are unable to read with magniÞcation.

Most reading machines, such as the Kurzweil Reading Machine, employ a computer-controlled camera that scans the lines of print and recognizes words from its programmed computer memory. These machines can read textbooks, articles, and tests, as well as a userÕs own written work. The voice synthesizer says each word aloud. The user puts the text on the glass plate of the scanner and pushes buttons on a control panel to activate the voice synthesizer. On several models, the user can control the speed, volume, and pitch of voice and can direct the machine to repeat material or to read punctuation marks.

The Optacon is an optical-to-tactual converting reading machine. It translates print into letter conÞgurations that are read with the Þngertips. The user slides a camera across a line of print with the right hand. Simultaneously, the left hand feels the letter conÞguration formed on an array of vibrating pins. The user must be extensively trained to use the machine.

Recording for the Blind and Dyslexic (RFB&D)

A non-proÞt, national service organization that records and lends educational books free of cost to the blind and the physically or perceptually handicapped. Based in New Jersey, the organization