Ophthalmology ( / ˌ ɒ f θ æ l ˈ m ɒ l ə dʒ i / , OFF -thal- MOL -ə-jee ) is a clinical and surgical specialty within medicine that deals with the diagnosis and treatment of eye disorders. A former term is oculism .
104-528: Topcon Corporation ( 株式会社トプコン , Kabushiki-gaisha Topukon ) is a Japanese manufacturer of optical equipment for ophthalmology and surveying . TOPCON was established in September 1932 based the merger of the surveying instruments division of K. Hattori & Co., Ltd. (now known as Seiko Holdinge Corporation ) in order to manufacture the optical instruments for the Japanese Army . Initially,
208-832: A medical degree , a doctor specialising in ophthalmology must pursue additional postgraduate residency training specific to that field. This may include a one-year integrated internship that involves more general medical training in other fields such as internal medicine or general surgery. Following residency, additional specialty training (or fellowship) may be sought in a particular aspect of eye pathology. Ophthalmologists prescribe medications to treat ailments, such as eye diseases, implement laser therapy, and perform surgery when needed. Ophthalmologists provide both primary and specialty eye care—medical and surgical. Most ophthalmologists participate in academic research on eye diseases at some point in their training and many include research as part of their career. Ophthalmology has always been at
312-452: A 120 roll, and twice that number of a 220 film. These correspond to 6x9, 6x7, 6x6, and 6x4.5 respectively (all dimensions in cm). Notable manufacturers of large format and roll film SLR cameras include Bronica , Graflex , Hasselblad , Seagull , Mamiya and Pentax . However, the most common format of SLR cameras has been 35 mm and subsequently the migration to digital SLR cameras, using almost identical sized bodies and sometimes using
416-596: A 3D inspection technology development/design company, in Canada. Entry into the 3D measurement and high-end print board fields. March 2010—Acquired InlandGEO Holding S.L., the largest dealer in Spain, to enhance sales channels for precision agricultural systems in the European, Middle-Eastern, and African markets. July 2010—Expanded Chinese subsidiary and established Topcon (Beijing) Opto-Electronics Development Corporation as
520-417: A certain range, providing the convenience of adjusting the scene capture without moving the camera or changing the lens. A prime lens, in contrast, has a fixed focal length. While less flexible, prime lenses often provide superior image quality, are typically lighter, and perform better in low light. Focus involves adjusting the lens elements to sharpen the image of the subject at various distances. The focus
624-454: A commonplace activity. The century also marked the rise of computational photography , using algorithms and AI to enhance image quality. Features like low-light and HDR photography , optical image stabilization, and depth-sensing became common in smartphone cameras. Most cameras capture light from the visible spectrum , while specialized cameras capture other portions of the electromagnetic spectrum , such as infrared . All cameras use
728-521: A critical role as it determines how much of the scene the camera can capture and how large the objects appear. Wide-angle lenses provide a broad view of the scene, while telephoto lenses capture a narrower view but magnify the objects. The focal length also influences the ease of taking clear pictures handheld, with longer lengths making it more challenging to avoid blur from small camera movements. Two primary types of lenses include zoom and prime lenses. A zoom lens allows for changing its focal length within
832-595: A general ophthalmologist in the Philippines, a candidate must have completed a doctor of medicine degree (MD) or its equivalent (e.g. MBBS), have completed an internship in Medicine, have passed the physician licensure exam, and have completed residency training at a hospital accredited by the Philippine Board of Ophthalmology (accrediting arm of PAO). Attainment of board certification in ophthalmology from
936-528: A large textbook, The Polished Book on Experimental Ophthalmology , divided into two parts, On the Theory of Ophthalmology and Simple and Compounded Ophthalmic Drugs . Avicenna wrote in his Canon "rescheth", which means "retiformis", and Gerard of Cremona translated this at approximately 1150 into the new term "retina". In the seventeenth and eighteenth centuries, hand lenses were used by Malpighi , microscopes by Leeuwenhoek , preparations for fixing
1040-400: A magnifier loupe, view finder, angle finder, and focusing rail/truck. Some professional SLRs can be provided with interchangeable finders for eye-level or waist-level focusing, focusing screens , eyecup, data backs, motor-drives for film transportation or external battery packs. In photography, the single-lens reflex camera (SLR) is provided with a mirror to redirect light from the lens to
1144-860: A manufacturing base in the emerging Chinese market. July 2010—Reorganized sales subsidiary in Singapore, established Topcon Singapore Holdings Pte. Ltd. as a holding company. Established new Positioning and Eye Care sales companies. August 2010—Established Topcon Medical Laser Systems, Inc. by acquiring retina and glaucoma business of OptiMedica (U.S.A) and entered therapeutic laser market. January 2011—Established Topcon Positioning Middle East and Africa FZE to expand Positioning Business in Middle Eastern and African market. November 2014—Acquired Wachendorff Elektronik GmbH and Wachendorff Electronics Inc. September 2015—Toshiba sells its shares of Topcon. April 2018—Established Topcon Healthcare Solutions, Inc.
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#17327875025021248-399: A mechanical or electronic shutter, the latter of which is common in smartphone cameras. Electronic shutters either record data from the entire sensor simultaneously (a global shutter) or record the data line by line across the sensor (a rolling shutter). In movie cameras, a rotary shutter opens and closes in sync with the advancement of each frame of film. The duration for which the shutter
1352-518: A medical software company based in Oakland, New Jersey. Their primary focus is the eye-care industry. July 2021—Topcon Corporation acquired VISIA Imaging S.r.l, an ophthalmic device manufacturer headquartered in suburban Florence, Italy. Tokyo Kogaku produced cameras , beginning with a 6×4.5 cm medium format model, Lord in 1937. A 127 film camera followed the next year. The Primoflex I twin-lens reflex camera came out in 1951. The Topcon 35A
1456-523: A nationwide GPS continuous observation system to Geographical Survey Institute, Ministry of Construction, Japanese Government. July 2000—Acquired Javad Positioning Systems Inc. in the United States and started selling precision GPS receivers and related system products. July 2001—Established Topcon America Corporation in New Jersey, U.S.A., as a holding company. Reorganized the subsidiaries in
1560-556: A residency in ophthalmology. Ophthalmologists typically perform optical, medical and surgical eye care. In Australia and New Zealand , the FRACO or FRANZCO is the equivalent postgraduate specialist qualification. The structured training system takes place over five years of postgraduate training. Overseas-trained ophthalmologists are assessed using the pathway published on the RANZCO website. Those who have completed their formal training in
1664-409: A section is devoted to eye diseases. Prior to Hippocrates , physicians largely based their anatomical conceptions of the eye on speculation, rather than empiricism . They recognized the sclera and transparent cornea running flushly as the outer coating of the eye, with an inner layer with pupil, and a fluid at the centre. It was believed, by Alcamaeon (fifth century BC) and others, that this fluid
1768-409: A short burst of bright light during exposure and is a commonly used artificial light source in photography. Most modern flash systems use a battery-powered high-voltage discharge through a gas-filled tube to generate bright light for a very short time (1/1,000 of a second or less). Many flash units measure the light reflected from the flash to help determine the appropriate duration of the flash. When
1872-429: A small display, offering a wider range of information such as live exposure previews and histograms, albeit at the cost of potential lag and higher battery consumption. Specialized viewfinder systems exist for specific applications, like subminiature cameras for spying or underwater photography . Parallax error , resulting from misalignment between the viewfinder and lens axes, can cause inaccurate representations of
1976-405: A specialized trade in the 1850s, designs and sizes were standardized. The latter half of the century witnessed the advent of dry plates and roll-film , prompting a shift towards smaller and more cost-effective cameras, epitomized by the original Kodak camera, first produced in 1888. This period also saw significant advancements in lens technology and the emergence of color photography, leading to
2080-563: A surge in camera ownership. The first half of the 20th century saw continued miniaturization and the integration of new manufacturing materials. After World War I, Germany took the lead in camera development, spearheading industry consolidation and producing precision-made cameras. The industry saw significant product launches such as the Leica camera and the Contax , which were enabled by advancements in film and lens designs. Additionally, there
2184-462: A surgical procedure. An eye surgeon is responsible for selecting the appropriate surgical procedure for the patient and for taking the necessary safety precautions. Ophthalmology includes subspecialities that deal either with certain diseases or diseases of certain parts of the eye. Some of them are: Medical retina and vitreo-retinal surgery sometimes are combined and together they are called posterior segment subspecialisation The Greek roots of
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#17327875025022288-1061: A surveying instrument sales company. December 1976—Established Topcon Medical Japan Co., Ltd., a medical instrument sales company. April 1978—Started selling an electric distance meter DM-C1 adopting a near-infrared. October 1978—Started selling a refractometer RM-100 incorporating near-infrared beam and a television system. March 1979—Established Topcon Singapore Pte. Ltd. in Singapore. April 1986—Established Topcon Optical (H.K.) Ltd. in Hong Kong. September 1986, listed on First Sections of Tokyo and Osaka Stock Exchanges. April 1989—Changed its corporate name to TOPCON CORPORATION. April 1991—Entry into electron beam business. December 1991—Built an engineering center in corporate premises. September 1994—Established Topcon Laser Systems, Inc. (currently Topcon Positioning Systems, Inc.) in California, U.S.A., acquired Advanced Grade Technology, advanced into machine control business. October 1994—Delivered
2392-673: A takeover bid for shares of Sokkia Co., Ltd. and made it a subsidiary to enhance competitiveness of the positioning business in the global market. July 2008—Established in Turin (Italy) TIERRA SPA, a joint venture with Divitech spa entering in the Telematic and Remote Diagnostic market segments. June 2009—Acquired shares of Italian wireless communications manufacturer DESTURA s.r.l. to strengthen operations in mobile communications, machine controls, and agricultural IT market segments. October 2009—Established Topcon 3D Inspection Laboratories, Inc.,
2496-403: Is a non-invasive medical imaging technique for mapping the anterior curvature of the cornea , the outer structure of the eye . Ultrasonography of the eyes may be performed by an ophthalmologist. Eye surgery , also known as ocular surgery, is surgery performed on the eye or its adnexa by an ophthalmologist. The eye is a fragile organ, and requires extreme care before, during, and after
2600-422: Is a medical technological platform used to assess ocular structures. The information is then used by physicians to assess staging of pathological processes and confirm clinical diagnoses. Subsequent OCT scans are used to assess the efficacy of managing diabetic retinopathy, age-related macular degeneration, and glaucoma. Optical coherence tomography angiography (OCTA) and Fluorescein angiography to visualize
2704-475: Is adjusted through the focus ring on the lens, which moves the lens elements closer or further from the sensor. Autofocus is a feature included in many lenses, which uses a motor within the lens to adjust the focus quickly and precisely based on the lens's detection of contrast or phase differences. This feature can be enabled or disabled using switches on the lens body. Advanced lenses may include mechanical image stabilization systems that move lens elements or
2808-416: Is adjusted, the opening expands and contracts in increments called f-stops . The smaller the f-stop, the more light is allowed to enter the lens, increasing the exposure. Typically, f-stops range from f / 1.4 to f / 32 in standard increments: 1.4, 2, 2.8, 4, 5.6, 8, 11, 16, 22, and 32. The light entering the camera is halved with each increasing increment. The wider opening at lower f-stops narrows
2912-617: Is also considered the founding father of the German Ophthalmological Society. Numerous ophthalmologists fled Germany after 1933 as the Nazis began to persecute those of Jewish descent. A representative leader was Joseph Igersheimer (1879–1965), best known for his discoveries with arsphenamine for the treatment of syphilis. He fled to Turkey in 1933. As one of eight emigrant directors in the Faculty of Medicine at
3016-462: Is an assembly of multiple optical elements, typically made from high-quality glass. Its primary function is to focus light onto a camera's film or digital sensor, thereby producing an image. This process significantly influences image quality, the overall appearance of the photo, and which parts of the scene are brought into focus. A camera lens is constructed from a series of lens elements, small pieces of glass arranged to form an image accurately on
3120-408: Is an instrument used to capture and store images and videos, either digitally via an electronic image sensor , or chemically via a light-sensitive material such as photographic film . As a pivotal technology in the fields of photography and videography, cameras have played a significant role in the progression of visual arts, media, entertainment, surveillance, and scientific research. The invention of
3224-440: Is assessed by both highly qualified Pakistani and eminent international ophthalmic consultants. As a prerequisite to the final examinations, an intermediate module, an optics and refraction module, and a dissertation written on a research project carried out under supervision is also assessed. Moreover, a two-and-a-half-year residency program leads to an MCPS while a two-year training of DOMS is also being offered. For candidates in
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3328-433: Is correctly placed. The photographer then winds the film, either manually or automatically depending on the camera, to position a blank portion of the film in the path of the light. Each time a photo is taken, the film advance mechanism moves the exposed film out of the way, bringing a new, unexposed section of film into position for the next shot. The film must be advanced after each shot to prevent double exposure — where
3432-464: Is dictated by the sensor's size and properties, necessitating storage media such as Compact Flash , Memory Sticks , and SD (Secure Digital) cards . Modern digital cameras typically feature a built-in monitor for immediate image review and adjustments. Digital images are also more readily handled and manipulated by computers, offering a significant advantage in terms of flexibility and post-processing potential over traditional film. A flash provides
3536-487: Is measured using a built-in light meter or exposure meter. Taken through the lens (called TTL metering ), these readings are taken using a panel of light-sensitive semiconductors . They are used to calculate optimal exposure settings. These settings are typically determined automatically as the reading is used by the camera's microprocessor . The reading from the light meter is incorporated with aperture settings, exposure times, and film or sensor sensitivity to calculate
3640-574: Is now called Moorfields Eye Hospital . Clinical developments at Moorfields and the founding of the Institute of Ophthalmology (now part of the University College London ) by Sir Stewart Duke-Elder established the site as the largest eye hospital in the world and a nexus for ophthalmic research. In Berlin, ophthalmologist Albrecht von Graefe introduced iridectomy as a treatment for glaucoma and improved cataract surgery, he
3744-400: Is open is called the shutter speed or exposure time . Typical exposure times can range from one second to 1/1,000 of a second, though longer and shorter durations are not uncommon. In the early stages of photography, exposures were often several minutes long. These long exposure times often resulted in blurry images, as a single object is recorded in multiple places across a single image for
3848-465: Is pulled across the film plane during exposure. The focal-plane shutter is typically used in single-lens reflex (SLR) cameras, since covering the film (rather than blocking the light passing through the lens) allows the photographer to view the image through the lens at all times, except during the exposure itself. Covering the film also facilitates removing the lens from a loaded camera, as many SLRs have interchangeable lenses. A digital camera may use
3952-547: Is replaced by the film to make the exposure; they are suitable for static subjects only and are slow to use. The earliest cameras produced in significant numbers were plate cameras , using sensitized glass plates. Light entered a lens mounted on a lens board which was separated from the plate by extendible bellows. There were simple box cameras for glass plates but also single-lens reflex cameras with interchangeable lenses and even for color photography ( Autochrome Lumière ). Many of these cameras had controls to raise, lower, and tilt
4056-598: Is required after completing an MBBS degree. The postgraduate degree in ophthalmology is called medical doctor in ophthalmology. Currently, this degree is provided by Tilganga Institute of Ophthalmology, Tilganga, Kathmandu, BPKLCO, Institute of Medicine, TU, Kathmandu, BP Koirala Institute of Health Sciences, Dharan, Kathmandu University, Dhulikhel, and National Academy of Medical Science, Kathmandu. A few Nepalese citizens also study this subject in Bangladesh, China, India, Pakistan, and other countries. All graduates have to pass
4160-590: Is required before eligibility to work in consultant posts. Some trainees take extra time to obtain MSc , MD or PhD degrees and to undertake clinical fellowships in the UK, Australia, and the United States. In Pakistan , after MBBS, a four-year full-time residency program leads to an exit-level FCPS examination in ophthalmology, held under the auspices of the College of Physicians and Surgeons, Pakistan. The tough examination
4264-783: Is undertaken. The residency typically lasts five years, which culminates in fellowship of the Royal College of Surgeons of Canada (FRCSC). Subspecialty training is undertaken by approximately 30% of fellows (FRCSC) in a variety of fields from anterior segment , cornea , glaucoma , vision rehabilitation , uveitis , oculoplastics , medical and surgical retina, ocular oncology , Ocular pathology , or neuro-ophthalmology . Approximately 35 vacancies open per year for ophthalmology residency training in all of Canada. These numbers fluctuate per year, ranging from 30 to 37 spots. Of these, up to ten spots are at French-speaking universities in Quebec. At
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4368-526: The Canon Pellix and others with a small periscope such as in the Corfield Periflex series. The large-format camera, taking sheet film, is a direct successor of the early plate cameras and remained in use for high-quality photography and technical, architectural, and industrial photography. There are three common types: the view camera, with its monorail and field camera variants, and
4472-659: The College of Ophthalmology and Allied Vision Sciences , in Lahore and the Pakistan Institute of Community Ophthalmology in Peshawar. Subspecialty fellowships also are being offered in the fields of pediatric ophthalmology and vitreoretinal ophthalmology. King Edward Medical University , Al Shifa Trust Eye Hospital Rawalpindi, and Al- Ibrahim Eye Hospital Karachi also have started a degree program in this field. In
4576-581: The Royal College of Surgeons of Edinburgh grant MRCOphth/FRCOphth and MRCSEd/FRCSEd, (although membership is no longer a prerequisite for fellowship), the Royal College of Glasgow grants FRCS. Postgraduate work as a specialist registrar and one of these degrees is required for specialization in eye diseases . Such clinical work is within the NHS, with supplementary private work for some consultants. Only 2.3 ophthalmologists exist per 100,000 population in
4680-648: The Royal College of Surgeons of Ireland grants membership (MRCSI (Ophth)) and fellowship (FRCSI (Ophth)) qualifications in conjunction with the Irish College of Ophthalmologists. Total postgraduate training involves an intern year, a minimum of three years of basic surgical training, and a further 4.5 years of higher surgical training. Clinical training takes place within public, Health Service Executive -funded hospitals in Dublin , Sligo , Limerick , Galway , Waterford , and Cork . A minimum of 8.5 years of training
4784-461: The University of Istanbul , he built a modern clinic and trained students. In 1939, he went to the United States, becoming a professor at Tufts University . German ophthalmologist, Gerhard Meyer-Schwickerath is widely credited with developing the predecessor of laser coagulation, photocoagulation. In 1946, Igersheimer conducted the first experiments on light coagulation. In 1949, he performed
4888-412: The press camera . They have extensible bellows with the lens and shutter mounted on a lens plate at the front. Backs taking roll film and later digital backs are available in addition to the standard dark slide back. These cameras have a wide range of movements allowing very close control of focus and perspective. Composition and focusing are done on view cameras by viewing a ground-glass screen which
4992-686: The tear ducts . The Indian surgeon Sushruta wrote the Sushruta Samhita in Sanskrit in approximately the sixth century BC, which describes 76 ocular diseases (of these, 51 surgical) as well as several ophthalmological surgical instruments and techniques. His description of cataract surgery was compatible with the method of couching . He has been described as one of the first cataract surgeons. Medieval Islamic Arabic and Persian scientists (unlike their classical predecessors) considered it normal to combine theory and practice, including
5096-558: The European market - one overseeing eye care business and the other overseeing positioning business - with Topcon Europe B.V. as the holding company. July 2005—Transferred from part of the Hoya Corporation Vision Care Company's ophthalmic instruments segment in Japan. April 2006—Implemented two-for-one stock split. August 2006—Acquired ANKA Systems, Inc., in the United States for full-fledged entry into
5200-486: The Greek philosopher of the second century AD gave a detailed description of cataract surgery by the couching method. The Greek physician Galen (second century AD) remedied some mistaken descriptions, including about the curvature of the cornea and lens, the nature of the optic nerve, and the existence of a posterior chamber . Although this model was a roughly correct modern model of the eye, it contained errors. Still, it
5304-551: The Nepal Medical Council Licensing Exam to become a registered ophthalmologists in Nepal. The concurrent residency training is in the form of a PG student (resident) at a medical college, eye hospital, or institution according to the degree providing university's rules and regulations. Nepal Ophthalmic Society holds regular conferences and actively promotes continuing medical education. In Ireland ,
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#17327875025025408-567: The PBO is essential in acquiring privileges in most major health institutions. Graduates of residency programs can receive further training in ophthalmology subspecialties, such as neuro-ophthalmology, retina, etc. by completing a fellowship program that varies in length depending on each program's requirements. In the United Kingdom , three colleges grant postgraduate degrees in ophthalmology. The Royal College of Ophthalmologists (RCOphth) and
5512-592: The Philippines, Ophthalmology is considered a medical specialty that uses medicine and surgery to treat diseases of the eye. There is only one professional organization in the country that is duly recognized by the PMA and the PCS: the Philippine Academy of Ophthalmology (PAO). PAO and the state-standard Philippine Board of Ophthalmology (PBO) regulates ophthalmology residency programs and board certification. To become
5616-955: The Topcon R, with semi-auto lens and an interchangeable finder. March 1960—Became an affiliate of Tokyo Shibaura Electric Co., Ltd. (currently Toshiba Corporation ). May 1963—Released the first single-lens reflex camera with through the lens metering (TTL), the TOPCON RE Super. October 1969—Established Tokyo Kogaku Seiki Kabushikikaisha (currently OPTONEXUS Co., Ltd.) in Tamura-gun, Fukushima Prefecture. April 1970—Established Topcon Europe N.V.(currently Topcon Europe B.V.) in Rotterdam, The Netherlands. September 1970—Established Topcon Instrument Corporation of America (currently Topcon Medical Systems, Inc.) January 1975—Established Topcon Sokki Co., Ltd. (currently Topcon Sales corporation),
5720-548: The UK and have the CCST or CCT, usually are deemed to be comparable. In Bangladesh to be an ophthalmologist the basic degree is an MBBS. Then they have to obtain a postgraduate degree or diploma in an ophthalmology specialty. In Bangladesh, these are diploma in ophthalmology, diploma in community ophthalmology, fellow or member of the College of Physicians and Surgeons in ophthalmology, and Master of Science in ophthalmology. In Canada , after medical school an ophthalmology residency
5824-664: The UK – fewer pro rata than in any nations in the European Union. Ophthalmologists typically complete four years of undergraduate studies, four years of medical school and four years of eye-specific training (residency). Some pursue additional training, known as a fellowship - typically one to two years. Ophthalmologists are physicians who specialize in the eye and related structures. They perform medical and surgical eye care and may also write prescriptions for corrective lenses. They often manage late stage eye disease, which typically involves surgery. Camera A camera
5928-562: The United States by 2003. In contrast, the film camera industry in the UK, Western Europe, and the USA declined during this period, while manufacturing continued in the USSR, German Democratic Republic, and China, often mimicking Western designs. The 21st century witnessed the mass adoption of digital cameras and significant improvements in sensor technology. A major revolution came with the incorporation of cameras into smartphones, making photography
6032-510: The United States dividing them into the ophthalmic and medical instrument business and the positioning business. July 2002—Liquidated Topcon Singapore Pte. Ltd. and established Topcon South Asia Pte. Ltd. in Singapore. February 2004—Established Topcon (Beijing) Opto-Electronics Corporation in Beijing, China. July 2005—Reorganized sales subsidiaries in Europe and newly established two firms in
6136-413: The camera dates back to the 19th century and has since evolved with advancements in technology, leading to a vast array of types and models in the 21st century. Cameras function through a combination of multiple mechanical components and principles. These include exposure control, which regulates the amount of light reaching the sensor or film; the lens, which focuses the light; the viewfinder, which allows
6240-760: The camera line into the US, with the RE-Super being rebranded as the Super-D. In about 1965, the US Navy tested cameras from several Japanese and German manufacturers (including the Nikon F ). The Topcon Super D was the winner of this competition, and was used exclusively by the Navy until 1977. Ophthalmology An ophthalmologist is a physician who undergoes subspecialty training in medical and surgical eye care. Following
6344-410: The camera through an aperture, an opening adjusted by overlapping plates called the aperture ring. Typically located in the lens, this opening can be widened or narrowed to alter the amount of light that strikes the film or sensor. The size of the aperture can be set manually, by rotating the lens or adjusting a dial or automatically based on readings from an internal light meter. As the aperture
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#17327875025026448-520: The company produced surveying instruments, binoculars and cameras, as well as sniper scopes used mainly by the Army. In April 1933, TOPCON built their head offices and main factory at 180, Shimura-motohasunuma-cho, Itabashi-ku , Tokyo. In August 1945, TOPCON temporalily closed their factories after the end of World War II , but soon gained the authorization from the Tokyo Governor to convert
6552-533: The composition, lighting, and exposure of their shots, enhancing the accuracy of the final image. Viewfinders fall into two primary categories: optical and electronic. Optical viewfinders, commonly found in Single-Lens Reflex (SLR) cameras, use a system of mirrors or prisms to reflect light from the lens to the viewfinder, providing a clear, real-time view of the scene. Electronic viewfinders, typical in mirrorless cameras, project an electronic image onto
6656-402: The crafting of precise instruments, and therefore, found it natural to combine the study of the eye with the practical application of that knowledge. Hunayn ibn Ishaq , and others beginning with the medieval Arabic period, taught that the crystalline lens is in the exact center of the eye. This idea was propagated until the end of the 1500s. Ibn al-Nafis , an Arabic native of Damascus, wrote
6760-422: The degree of magnification expected of the final image. The shutter, along with the aperture, is one of two ways to control the amount of light entering the camera. The shutter determines the duration that the light-sensitive surface is exposed to light. The shutter opens, light enters the camera and exposes the film or sensor to light, and then the shutter closes. There are two types of mechanical shutters:
6864-410: The duration of the exposure. To prevent this, shorter exposure times can be used. Very short exposure times can capture fast-moving action and eliminate motion blur. However, shorter exposure times require more light to produce a properly exposed image, so shortening the exposure time is not always possible. Like aperture settings, exposure times increment in powers of two. The two settings determine
6968-430: The end of the five years, the graduating ophthalmologist must pass the oral and written portions of the Royal College exam in either English or French. In India , after completing MBBS degree, postgraduate study in ophthalmology is required. The degrees are doctor of medicine, master of surgery, diploma in ophthalmic medicine and surgery, and diplomate of national board. The concurrent training and work experience are in
7072-528: The evolution of the technology in the 19th century was driven by pioneers like Thomas Wedgwood , Nicéphore Niépce , and Henry Fox Talbot . First using the camera obscura for chemical experiments, they ultimately created cameras specifically for chemical photography, and later reduced the camera's size and optimized lens configurations. The introduction of the daguerreotype process in 1839 facilitated commercial camera manufacturing, with various producers contributing diverse designs. As camera manufacturing became
7176-408: The exposure value (EV), a measure of how much light is recorded during the exposure. There is a direct relationship between the exposure times and aperture settings so that if the exposure time is lengthened one step, but the aperture opening is also narrowed one step, then the amount of light that contacts the film or sensor is the same. In most modern cameras, the amount of light entering the camera
7280-528: The eye for study by Ruysch , and later the freezing of the eye by Petit . This allowed for detailed study of the eye and an advanced model. Some mistakes persisted, such as: why the pupil changed size (seen to be vessels of the iris filling with blood), the existence of the posterior chamber , and the nature of the retina. Unaware of their functions, Leeuwenhoek noted the existence of photoreceptors, however, they were not properly described until Gottfried Reinhold Treviranus in 1834. Jacques Daviel performed
7384-442: The eye, not one. One tube from each eye met within the skull. The Greek physician Rufus of Ephesus (first century AD) recognised a more modern concept of the eye, with conjunctiva , extending as a fourth epithelial layer over the eye. Rufus was the first to recognise a two-chambered eye, with one chamber from cornea to lens (filled with water), the other from lens to retina (filled with a substance resembling egg whites). Celsus
7488-498: The eyes or eyelids. The first ophthalmic surgeon in the UK was John Freke , appointed to the position by the governors of St. Bartholomew's Hospital in 1727. A major breakthrough came with the appointment of Baron de Wenzel (1724–90), a German who became the oculist to King George III of Great Britain in 1772. His skill at removing cataracts legitimized the field. The first dedicated ophthalmic hospital opened in 1805 in London; it
7592-586: The factory for production of civil products. By the end of the year, the factory reopened to manufacture binoculars and surveying instruments. They established Yamagata Kikai Kyogo Kabushikikaisha (currently Topcon Yamagata Co., Ltd.) in 1946 in Yamagata-shi, Yamagata Prefecture . In December 1947, TOPCON started selling lens meters and an Ophthalmic and Medical Instruments business. In May of 1949, they listed their stock on Tokyo and Osaka Stock Exchanges . 1957—released its first single-lens reflex camera,
7696-543: The finger pressure was released. The Asahiflex II , released by Japanese company Asahi (Pentax) in 1954, was the world's first SLR camera with an instant return mirror. In the single-lens reflex camera, the photographer sees the scene through the camera lens. This avoids the problem of parallax which occurs when the viewfinder or viewing lens is separated from the taking lens. Single-lens reflex cameras have been made in several formats including sheet film 5x7" and 4x5", roll film 220/120 taking 8,10, 12, or 16 photographs on
7800-588: The first documented planned primary cataract extraction on Sep. 18, 1750 in Cologne. Georg Joseph Beer (1763–1821) was an Austrian ophthalmologist and leader of the First Viennese School of Medicine. He introduced a flap operation for treatment of cataract (Beer's operation), as well as having popularized the instrument used to perform the surgery (Beer's knife). In North America, indigenous healers treated some eye diseases by rubbing or scraping
7904-459: The first successful treatment of a retinal detachment with a light beam (light coagulation) with a self-constructed device on the roof of the ophthalmic clinic at the University of Hamburg-Eppendorf . Polish ophthalmology dates to the thirteenth century. The Polish Ophthalmological Society was founded in 1911. A representative leader was Adam Zamenhof (1888–1940), who introduced certain diagnostic, surgical, and nonsurgical eye-care procedures. He
8008-556: The flash is attached directly to the camera—typically in a slot at the top of the camera (the flash shoe or hot shoe) or through a cable—activating the shutter on the camera triggers the flash, and the camera's internal light meter can help determine the duration of the flash. Additional flash equipment can include a light diffuser , mount and stand, reflector, soft box , trigger and cord. Accessories for cameras are mainly used for care, protection, special effects, and functions. Large format cameras use special equipment that includes
8112-612: The forefront of medical research with a long history of advancement and innovation in eye care. A brief list of some of the most common diseases treated by ophthalmologists: The most valued pharmaceutical companies worldwide whose leading products are in Ophthalmology are Regeneron (United States) for Macular degeneration (AMD) treatment and Bausch Health (Canada) for Front of eye. Following are examples of examination methods performed during an eye examination that enables diagnosis Optical coherence tomography (OCT)
8216-587: The form of a junior residency at a medical college, eye hospital, or institution under the supervision of experienced faculty. Further work experience in the form of fellowship, registrar, or senior resident refines the skills of these eye surgeons. All members of the India Ophthalmologist Society and various state-level ophthalmologist societies hold regular conferences and actively promote continuing medical education. In Nepal , to become an ophthalmologist, three years of postgraduate study
8320-440: The front and the back of the human eye. The resulting signal is called the electrooculogram. Primary applications are in ophthalmological diagnosis and in recording eye movements . Visual field testing to detect dysfunction in central and peripheral vision which may be caused by various medical conditions such as glaucoma , stroke , pituitary disease , brain tumours or other neurological deficits. Corneal topography
8424-438: The image sensor itself to counteract camera shake, especially beneficial in low-light conditions or at slow shutter speeds. Lens hoods, filters, and caps are accessories used alongside a lens to enhance image quality, protect the lens, or achieve specific effects. The camera's viewfinder provides a real-time approximation of what will be captured by the sensor or film. It assists photographers in aligning, focusing, and adjusting
8528-498: The introduction of the affordable Ricohflex III TLR in 1952 to the first 35mm SLR with automatic exposure, the Olympus AutoEye in 1960, new designs and features continuously emerged. Electronics became integral to camera design in the 1970s, evident in models like Polaroid's SX-70 and Canon's AE-1 . Transition to digital photography marked the late 20th century, culminating in digital camera sales surpassing film cameras in
8632-426: The late 20th and early 21st century, use electronic sensors to capture and store images. The rapid development of smartphone camera technology in the 21st century has blurred the lines between dedicated cameras and multifunctional devices, profoundly influencing how society creates, shares, and consumes visual content. Beginning with the use of the camera obscura and transitioning to complex photographic cameras,
8736-467: The leaf-type shutter and the focal-plane shutter. The leaf-type uses a circular iris diaphragm maintained under spring tension inside or just behind the lens that rapidly opens and closes when the shutter is released. More commonly, a focal-plane shutter is used. This shutter operates close to the film plane and employs metal plates or cloth curtains with an opening that passes across the light-sensitive surface. The curtains or plates have an opening that
8840-437: The light-sensitive surface. Each element is designed to reduce optical aberrations , or distortions, such as chromatic aberration (a failure of the lens to focus all colors at the same point), vignetting (darkening of image corners), and distortion (bending or warping of the image). The degree of these distortions can vary depending on the subject of the photo. The focal length of the lens, measured in millimeters, plays
8944-578: The military, a stringent two-year graded course, with quarterly assessments, is held under Armed Forces Post Graduate Medical Institute in Rawalpindi. The M.S. in ophthalmology is also one of the specialty programs. In addition to programs for physicians, various diplomas and degrees for allied eyecare personnel are also being offered to produce competent optometrists, orthoptists, ophthalmic nurses, ophthalmic technologists, and ophthalmic technicians in this field. These programs are being offered, notably by
9048-583: The ophthalmic network business in the United States. October 2006—Acquired KEE Technologies Pty Ltd., in Australia for entry into field of agriculture. April 2007—In order to build a global group and quick business expansion, Topcon adopted three business structures, Positioning Business Unit, Eye Care Business Unit and Finetech Business Unit. May 2007—Business rights for mobile control (navigation systems, ITS and others) transferred to U.S. subsidiary from Javad Navigation Systems, Inc. February 2008—Conducted
9152-429: The optimal exposure. Light meters typically average the light in a scene to 18% middle gray. More advanced cameras are more nuanced in their metering—weighing the center of the frame more heavily (center-weighted metering), considering the differences in light across the image (matrix metering), or allowing the photographer to take a light reading at a specific point within the image (spot metering). A camera lens
9256-407: The range of focus so the background is blurry while the foreground is in focus. This depth of field increases as the aperture closes. A narrow aperture results in a high depth of field, meaning that objects at many different distances from the camera will appear to be in focus. What is acceptably in focus is determined by the circle of confusion , the photographic technique, the equipment in use and
9360-408: The same basic design: light enters an enclosed box through a converging or convex lens and an image is recorded on a light-sensitive medium. A shutter mechanism controls the length of time that light enters the camera. Most cameras also have a viewfinder, which shows the scene to be recorded, along with means to adjust various combinations of focus , aperture and shutter speed . Light enters
9464-429: The same lens systems. Almost all SLR cameras use a front-surfaced mirror in the optical path to direct the light from the lens via a viewing screen and pentaprism to the eyepiece. At the time of exposure, the mirror is flipped up out of the light path before the shutter opens. Some early cameras experimented with other methods of providing through-the-lens viewing, including the use of a semi-transparent pellicle as in
9568-873: The same section of film is exposed to light twice, resulting in overlapped images. Once all frames on the film roll have been exposed, the film is rewound back into the cartridge, ready to be removed from the camera for developing. In digital cameras, sensors typically comprise Charge-Coupled Devices (CCDs) or Complementary Metal-Oxide-Semiconductor (CMOS) chips, both of which convert incoming light into electrical charges to form digital images. CCD sensors, though power-intensive, are recognized for their excellent light sensitivity and image quality. Conversely, CMOS sensors offer individual pixel readouts, leading to less power consumption and faster frame rates, with their image quality having improved significantly over time. Digital cameras convert light into electronic data that can be directly processed and stored. The volume of data generated
9672-404: The shutter is briefly opened to allow light to pass during the exposure. Loading film into a film camera is a manual process. The film, typically housed in a cartridge, is loaded into a designated slot in the camera. One end of the film strip, the film leader, is manually threaded onto a take-up spool. Once the back of the camera is closed, the film advance lever or knob is used to ensure the film
9776-402: The subject's position. While negligible with distant subjects, this error becomes prominent with closer ones. Some viewfinders incorporate parallax-compensating devices to mitigate that issue. Image capture in a camera occurs when light strikes a light-sensitive surface: photographic film or a digital sensor . Housed within the camera body, the film or sensor records the light's pattern when
9880-734: The user to preview the scene; and the film or sensor, which captures the image. Several types of cameras exist, each suited to specific uses and offering unique capabilities. Single-lens reflex (SLR) cameras provide real-time, exact imaging through the lens. Large-format and medium-format cameras offer higher image resolution and are often used in professional and artistic photography. Compact cameras, known for their portability and simplicity, are popular in consumer photography. Rangefinder cameras , with separate viewing and imaging systems, were historically widely used in photojournalism. Motion picture cameras are specialized for filming cinematic content, while digital cameras , which became prevalent in
9984-408: The vascular networks of the retina and choroid. Electroretinography (ERG) measures the electrical responses of various cell types in the retina , including the photoreceptors ( rods and cones ), inner retinal cells ( bipolar and amacrine cells), and the ganglion cells . Electrooculography ( EOG ) is a technique for measuring the corneo-retinal standing potential that exists between
10088-428: The viewfinder prior to releasing the shutter for composing and focusing an image. When the shutter is released, the mirror swings up and away, allowing the exposure of the photographic medium , and instantly returns after the exposure is finished. No SLR camera before 1954 had this feature, although the mirror on some early SLR cameras was entirely operated by the force exerted on the shutter release and only returned when
10192-481: The word ophthalmology are ὀφθαλμός ( ophthalmos , "eye") and -λoγία (- logia , "study, discourse"), i.e., "the study of eyes". The discipline applies to all animal eyes, whether human or not, since the practice and procedures are quite similar with respect to disease processes, although there are differences in the anatomy or disease prevalence. In the Ebers Papyrus from ancient Egypt dating to 1550 BC,
10296-455: Was a marked increase in accessibility to cinematography for amateurs with Eastman Kodak's production of the first 16-mm and 8-mm reversal safety films. The World War II era saw a focus on the development of specialized aerial reconnaissance and instrument-recording equipment, even as the overall pace of non-military camera innovation slowed. In the second half of the century, Japanese manufacturers in particular advanced camera technology. From
10400-419: Was a polymath who made contributions to many fields of science and invented the ophthalmoscope in 1851. They both made theoretical calculations on image formation in optical systems and also had studied the optics of the eye. Ophthalmologists are physicians ( MD/DO in the U.S. or MBBS in the UK and elsewhere or DO /DOMS/DNB, who typically complete an undergraduate degree, general medical school, followed by
10504-674: Was executed by the German Nazis in 1940. Zofia Falkowska (1915–93) head of the Faculty and Clinic of Ophthalmology in Warsaw from 1963 to 1976, was the first to use lasers in her practice. The prominent physicists of the late nineteenth and early twentieth centuries included Ernst Abbe (1840–1905), a co-owner of at the Zeiss Jena factories in Germany, where he developed numerous optical instruments. Hermann von Helmholtz (1821–1894)
10608-453: Was not advanced upon again until after Vesalius . A ciliary body was then discovered and the sclera, retina, choroid, and cornea were seen to meet at the same point. The two chambers were seen to hold the same fluid, as well as the lens being attached to the choroid. Galen continued the notion of a central canal, but he dissected the optic nerve and saw that it was solid. He mistakenly counted seven optical muscles, one too many. He also knew of
10712-438: Was the medium of vision and flowed from the eye to the brain by a tube. Aristotle advanced such ideas with empiricism. He dissected the eyes of animals, and discovering three layers (not two), found that the fluid was of a constant consistency with the lens forming (or congealing) after death, and the surrounding layers were seen to be juxtaposed. He and his contemporaries further put forth the existence of three tubes leading from
10816-729: Was unveiled in 1953. In 1960 the company produced a 6x9 press camera on order from the Tokyo Metropolitan Police Department . It initially used a Mamiya lens; civilian models became available with Topcon lenses. With the 35 mm Topcon RE Super of 1963, the company pioneered full-aperture, through-the-lens metering. Round about 1973 the production of the SLR IC-1 AUTO started; „IC“ means „Integrated Circuit“, used for aperture control. The company continued to innovate until leaving that line of business in 1981. The Charles Beseler Company imported
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