The United States of America, also known as the United States, the U.S., the U.S.A., the U.S. of A, the States, and America, is a country in North America. A federal republic, the United States shares land borders with Canada and Mexico, and extends from the Atlantic Ocean to the Pacific Ocean. Its capital is Washington, D.C.
The present-day continental United States has been inhabited for at least 15,000 years by Native Americans. After 16th-century European exploration and settlement, the English established new colonies, and gained control of others, in the eastern portion of the continent in the 17th and early 18th centuries. On 4 July 1776, at war with Britain over fair governance, thirteen of these colonies declared their independence; in 1783, the war ended in British acceptance of the new nation. Since then, the country has more than quadrupled in size: it now consists of 50 states, one federal district, and a number of overseas territories.
At over 3.7 million square miles (over 9.1 million km²), the U.S. is the third largest country by area. It is also the world's third most populous nation, with nearly 300 million people.
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United States :: North America

American Academy of Ophthalmology - Providing authoritative information about eye care for the public and members.
Meta Description: [ American Academy of Ophthalmology ]
American Board of Ophthalmology - Information on certification and recertification of ophthalmologists in the United States.
American Society of Cataract and Refractive Surgery - Offers information on general eye care, cataract and refractive surgery.
Meta Description: [ ASCRS is an international educational and scientific organization whose 9,000 member ophthalmologists specialize in cataract and refractive surgery ]
American Society of Ophthalmic Plastic and Reconstructive Surgery - Advancing education, research and the quality of clinical practice in plastic and reconstructive surgery.
Meta Description: [ The purpose of ASOPRS is to advance education, research and the quality of clinical practice in the fields of aesthetic, plastic and reconstructive surgery specializing in the face, orbits, eyelids, and lacrimal system ]
American Society of Ophthalmic Registered Nurses - Promote excellence in ophthalmic patient care and support the ophthalmic team through individual development, education, and evidence based practice.
American Society of Ophthalmic Ultrasound (ASOU) - A forum for exchange of ideas and experience, scientific communication and discussion of ophthalmic ultrasound system design, microimaging, experimental applications and the clinical practice of ophthalmic ultrasonography.
California Optometric Association - Health care for the public through the advancement of optometry.
Meta Description: [ For more than a century, California Optometric Association has been dedicated to making optometry a stronger, better, and more visible profession. ]
Central Florida Lions Eye Bank - Non-profit charitable organization dedicated to the recovery, evaluation and distribution of eye tissue for transplantation, research and education.
Meta Description: [ Central Florida Lions Eye & Tissue Bank Inc ]
Chicago Ophthalmological Society - Updates from Chicago ophthalmologists.
Council for Refractive Surgery Quality Assurance - Consumer organization providing information about wavefront, LASIK, and other refractive surgery techniques. Includes a database of certified practitioners.
Meta Description: [ Nonprofit Lasik patient advocacy, list of Lasik doctors certified by USAEyes.org, detailed Lasik eye surgery information. 50 Tough Questions For Your... ]
Deicke Center for Visual Rehabilitation - A comprehensive program of visual rehabilitation.
Donor Network of Arizona - Federally designated, not-for profit organ recovery organization for the state of Arizona.
Georgia Eye Bank - Provides corneal transplants and eye tissue to Georgia residents.
Meta Description: [ The Georgia Eye Bank prevents blindness and restores vision by recovering, processing and distributing donor eye tissue for corneal transplants and
by providing eye tissue for education and for research. ]
Houston Ophthalmological Society - Promotes dissemination of advanced ophthalmic knowledge to ophthalmologists from Houston and the surrounding region.
Joint Commission on Allied Health Personnel in Ophthalmology - The certifying agency for ophthalmic medical personnel.
Louisiana Lions Eye Foundation - Works in conjuction with local Lions clubs and The LSU Medical Center to research eye care.
Minnesota Academy of Ophthalmology - Association of eye surgeons in Minnesota.
NASA Vision Group - A team of scientists and engineers who conduct research on human vision and visual technology for NASA missions.
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National Alliance for Eye and Vision Research - Non-profit advocacy organization made up of a coalition of professional, consumer, and industry organizations involved in research in eye and vision disorders.
National Federation of Opticianry Schools - Promotion of formal opticianry education in the United States.
New Jersey Academy of Ophthalmology - Advocate the uniqueness of the profession of ophthalmology by educating both its members and the public in order to enable ophthalmologists to provide the highest quality of service to the public.
New York State Ophthalmological Society - Non-profit organization whose member Ophthalmologists are medical doctors (MDs) or doctors of osteopathy (DOs) specializing in the total care and treatment of the eye and visual system.
North American Neuro-Ophthalmology Society - Promotes the field of neuro-ophthalmology by supporting all forms of education, encouraging research, fostering clinical expertise and maintaining cordial exchanges.
Meta Description: [ North American Neuro-Ophthalmology Society is a professional organization with more than 400 members who are fully trained neurologists or ophthalmologists. ]
Ohio Ophthalmological Society - A group of professionals dedicated to ophthalmology in Ohio. Membership, education and referral services details are provided.
Oklahoma Academy of Ophthalmology - Official site of the Oklahoma Academy of Ophthalmology
Meta Description: [ The Oklahoma Academy of Ophthalmology is a 501(c)6 organization founded in 1986 to promote and advance the science and art of medical eye care in the state of Oklahoma. ]
Oregon Lions Sight and Hearing Foundation - Improves the quality of life in the areas of sight, hearing, diabetes and positive youth development.
Philadelphia Retina Endowment Fund - Established by members of the Retina Service of Wills Eye Hospital, located in Philadelphia, PA. The Fund is devoted to medical research related to diseases of the retina, macular degeneration (Bower Laboratory), the development of a resource guide for PA.
Texas Ophthalmological Association - Provide background information on ophthalmologists and on the TOA to non-ophthalmologist health care providers and the general public.
Meta Description: [ The Texas Ophthalmological Association is a non-profit (501(c)6) organization founded in 1956 to promote and advance the science and art of medical eye care in Texas. Among state ophthalmological societies in the US, the TOA has risen to prominence alongside the state of Texas, which boasts the ... ]
Virginia Society of Ophthalmology - A statewide nonprofit organization. News, articles, activities, calendar, and membership details.
Meta Description: [ The Virginia Society of Ophthalmology, a statewide nonprofit organization of ophthalmologists (Eye MDs), advocates for the best quality eye care through education, legislative efforts and community service. ]
Vision Share - A not-for-profit consortium of eye banks cooperating to provide mutually beneficial support services to its members.
Meta Description: [ Vision Share is a not-for-profit consortium of eye banks cooperating to provide mutually beneficial support services to its members. ]
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