LASIK corrective eye surgery is a type of refractive surgery for correcting myopia, hyperopia and astigmatism. LASIK or Laser Assisted In Situ Keratomileusis uses laser lights to fix your eyesight. Until the invention of contact lenses, eyeglasses alone were used to correct refractive vision errors. Modern techniques like Lasik, Photo refractive keratectomy (PRK) are performed for surgical insertion of artificial lenses to correct eyesight. Blurred vision is the failure of the eye's cornea and lens to refract light rays properly, which affects the images from being focused on the retina. Such blurriness is termed as refractive error. The major causes for refractive error include imperfectly shaped eyeball, cornea or lens.
The procedure involves permanently changing the shape of the cornea for better eyesight. Ophthalmologists use an excimer laser and special knife (microkeatome) to conduct the reshaping. You will be examined completely for any health related issues and the doctor also ensures that your eyes are healthy enough to undergo laser surgery. Few tests are done to measure the curve of the cornea, the size, and position of the pupils, the shape of the eyes and the thickness of the cornea. The tests enable the ophthalmologist to ensure that laser or LASIK eye surgery is an option to you. Ophthalmologists use a microkeratome, a special knife to cut a hinged flap of the corneal tissue. The flap is then folded to reach stroma, the middle section of the cornea, where actual reshaping takes place. An excimer laser is put into the stroma, to vaporize a predetermined portion of the cornea. In other words, pulses from the laser lights reshape the middle portion of the corneal tissue. Once the reshaping is done, the flap that was folded is replaced on the stroma. No stitching is required as both the tissue layers heal through natural process.
Tonometry test is a diagnostic test to measure the intraoccular pressure (IOP). When the tonometry test measures the pressure inside the eye, it can help in detecting glaucoma. Ensure that you take off your contact lenses. Do not wear tight clothing around the neck as it can lead to increased pressure inside the eye. Do not smoke a few hours prior to the tonometry test. The tonometry test is also conducted in cases of head or eye surgery and hyphema.
When the pressure builds up within the eye due to improper drainage, it can cause permanent damage to the ooptic nerve. Tonometry is done as part of routine eye examination to check for glaucoma. Anesthetic eye drops are used to numb the eye before using the tonometer. In the application method of testing intraoccular pressure, a paper stained with Fluorescein is placed to the side of the eye thereby staining the front of the eye. The tonometer is then brought close to the cornea for testing. Here the intraoccular pressure is measured by the amount of weight that is needed to flatten the cornea. This type of tonometry test can also be conducted with a pencil-like instrument, which will give instant digital measurement. The air puff method of conducting tonometry is a non-contact one where a puff of air is blown at your eye and change in the light reflected from the cornea is measured to arrive at the intraoccular pressure. This method is preferred for children and persons who have undergone LASIK surgery.
Myopia or nearsightedness is a condition where a person has trouble seeing things that are far away. The eye finds it difficult to focus the light directly on the retina since the physical length of the eye is greater than the optical length. Such a person suffering myopia finds distant objects blurred and might need to squint to see them clearer. Symptoms of myopia are eyestrain and sometimes headache. This is quickly noticed in school going children who have difficultly reading the blackboard. In fact myopia worsens during the growth years and then stabilizes after the teens. Regular eye tests with refraction test help in diagnosing the degree of refraction lens needed. Spectacles or contact lens are prescribed to correct the focus of the light image on the retina thereby producing a clear image. LASIK is also performed to correct myopia. Orthokeratology involves usage of special rigid contact lenses to flatten the cornea to reduce myopia.
Bibliography / Reference
Collection of Pages - Last revised Date: July 16, 2018