Laser in Ophthalmic surgery<br />Surgery to improve your eyesight is known as refractive surgery or vision correction. There are 2 different types: laser eye surgery and lens surgery. Both types of surgery can make you less dependent on glasses or contact lenses. Research shows that both are safe and effective. What type of refractive surgery will suit you best depends on a range of things, including your eyesight, eye health, age, budget and lifestyle. <br />Laser in Ophthalmic surgery:Tonometer<br />Tonometry is the procedure eye care professionals perform to determine the intraocular pressure (IOP), the fluid pressure inside the eye. It is an important test in the evaluation of patients at risk from glaucoma.[1] Most tonometers are calibrated to measure pressure in millimeters of mercury (mmHg)<br />Applanation tonometry<br />application tonometry the intraocular pressure (IOP) is inferred from the force required to flatten (applanate) a constant area of the cornea, for the Impart-Fick law.[2] The Maklak off tonometer was an early example of this method, while the Goldman tonometer is the most widely used version in current practice.[3] Because the probe makes contact with the cornea, a topical anesthetic, such as proxymetacaine, is introduced on to the surface of the eye in the form of an eye drop.<br />Goldmann tonometry<br />tonometry is considered to be the gold standard IOP test and is the most widely accepted method. A special disinfected prism is mounted on the tonometer head and then placed against the cornea. The examiner then uses a cobalt blue filter to view two green semicircles. The force applied to the tonometer head is then adjusted using a dial connected to a variable tension spring until the inner edges of the green semicircles in the viewfinder meet. When the area of a circle with diameter 3.06 mm (0.120 in) has been flattened, the opposing forces of corneal rigidity and the tear film are roughly approximate and cancel each other out allowing the pressure in the eye to be determined from the force applied. Like all non-invasive methods, it is inherently imprecise and may need to be adjusted.<br /> <br />Glaucoma and tonometry<br />Tonometry is a diagnostic test that measures the pressure inside your eye, which is called intraocular pressure (IOP). This measurement can help your doctor determine whether or not you may be at risk of glaucoma.<br />Glaucoma is a serious eye disease that can eventually lead to vision loss if untreated. In most cases of glaucoma, the fluid that normally bathes and nourishes the eye drains too slowly, causing pressure to build up. Without treatment, the increased pressure can eventually harm your optic nerve and cause vision loss. According to the American Academy of Ophthalmology (AAO), glaucoma is one of the leading causes of blindness in adults over the age of 60. The changes caused by glaucoma are often painless and can progress for years without you noticing. A tonometry test is critical for detecting the changes early. If your test results come back abnormal, your eye doctor will recommend additional testing to confirm that you have the disease.<br />