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Couching (ophthalmology) "Couching for cataract"; Wellcome Collection illustration of Indian doctors performing the technique. Couching is the earliest documented form of cataract surgery. It involves dislodging the lens of the eye, thus removing the cloudiness caused by the cataract. Couching was a precursor to modern cataract surgery and pars ...
Contact lenses. to correct refractive errors of the eye; a little invasive. Phoropter. used in refraction testing. Tonometers. used to determine the intraoccular pressure (IOP) - useful in glaucoma; video link for various types of tonometers. Speculum: to keep the eyes open during any operation. Universal eye speculum.
Cataract surgery is the most common application of lens removal surgery, and is usually associated with lens replacement. It is used to remove the natural lens of the eye when it has developed a cataract, a cloudy area in the lens that causes visual impairment. [ 4 ][ 10 ] Cataracts usually develop slowly and can affect one or both eyes. [ 4 ]
Global access to cataract surgery. Access to cataract surgery is very variable by country and region. Even in developed countries availability may vary significantly between rural and more densely populated areas. Cataract surgery is the removal of the natural lens of the eye that has developed a cataract, an opaque or cloudy area. [ 1]
In 1753, Samuel Sharp performed the first-recorded surgical removal of the entire lens and lens capsule, equivalent to what became known as intracapsular cataract extraction. The lens was removed from the eye through a limbal incision. [1] At the beginning of the 20th century, the standard surgical procedure was intracapsular cataract ...
Yoked prism can move the image away from primary gaze without the need for a constant head tilt or turn. [1] Prism correction is measured in prism dioptres. A prescription that specifies prism correction will also specify the "base". The base is the thickest part of the lens and is opposite from the apex. Light will be bent towards the base and ...
The intraocular lens did not find widespread acceptance in cataract surgery until the 1970s, when further developments in lens design and surgical techniques had come about. As of 2021, approximately four million cataract procedures take place annually in the U.S. and nearly 28 million worldwide, a large proportion in India.
Intraocular lenses that correct presbyopia are divided into two main categories: [1] Multifocal IOLs: achieve near and distance vision by having two (bifocal) or three (trifocal) focal points simultaneously. The function of multifocal IOL depends on the pupil size for refractive types. The concept is based on the principle that the pupil tends ...