Radial keratotomy

Radial keratotomy2019-04-25T18:59:46+00:00

Radial keratotomy

The refractive surgical procedure radial keratotomy (RK) is used for correcting myopia, which is nearsightedness. It was developed by Svyatoslav Fyodorov, who was a Russian ophthalmologist in the year of 1974. Newer operations have caused it to be largely supplanted, like LASIK, phakic intraocular lens, Epi-LASIK, and photorefractive keratectomy. In 1936 a Japanese ophthalmologist by the name of Tsutomu Sato began conducting research on anterior keratotomy and posterior keratotomy which was an early form of today’s refractive surgery with intentions of treating keratoconus, astigmatism, and myopia through making incisions to the cornea.

In the year of 1974, A boy who was involved in an accident had gotten glass in his eyes, and it was removed by Svyatoslav Fyodorov. This boy had been required to wear eyeglasses for the correction of myopia which had been caused from astigmatism and when his bicycle fell over his eye glasses were shattered upon impact, leaving particles lodged within his eyes. In order for the boy’s vision to be saved, Fyodorov immediately performed an operation that consisted of numerous radial incisions being made that started at the pupil, and extending to the periphery in the cornea, with a pattern like bicycle spokes. When the boy was healed, Fyodorov learned that the boy’s visual acuity had significantly improved due to the method used in removing the glass from the boy’s eyes.

The incisions for the procedure are performed using a diamond knife. The incisions, which only went deep enough to penetrate the superficial corneal stroma were less effective than the ones that reach further down into the cornea, whereas, the incisions should be made very deep. There is a study which cites that the incisions should be made deep enough of a depth to made it equivalent to the skinniest part of the thickness when four corneal layers are put together and should also be performed close to the cornea’s center. There are other sources which state that surgeries should leave 20 to 50 micrometers of incised corneal tissue (this is roughly equivalent to about 90% of the cornea’s depth, depending on the thickness norms).

The wounds that are healing should consist of fresh abutting corneal stroma, irregular fibrous connective tissue, and fibroblastic cells. Close to the surface of the wound there will be an epithelial plug and a bed of cells, these are what forms a normal epithelium (has fell into the wound). Sometimes this plug will be three to four times deeper than a normal layer. While the cells are migrating up and out of the depth to the surface, many with it are going to die before it can be reached. This will create breaches in those who may be healthy otherwise. Leaving the cornea wide open to infections. It is estimated that the risk is between 0.25% and 0.7%. It is unpredictable on the healing and is also slow to heal (even years after the surgery the wounds sometimes has not healed yet). The infection that occur with these wounds can also still exist years after the surgery, as there are 53% of these infections that occur late in their onset. Pseudomonas aeruginosa is the highly virulent bacterium is a pathogen which is most commonly involved in this type of infections.

There could be more scattering of light from using large epithelial plugs, and could lead to having an appearance consisting of visual phenomena, like flares or starbursts, extremely so in situations like night driving. The pupil responds to light/dark conditions by dilating, as this maximizes the amount of the scatter light can enter the eye(s). Patient might look for more surgical treatment in order to get rid of these symptoms. Those who have undergone RK could end up with partial blindness if they encounter increasing altitudes, as Beck Weathers, a mountaineer who himself had underwent RK, and he experienced himself during the Mount Everest disaster of 1996. During the RK procedure, patients who have myopia will receive incisions for relaxing the steep central cornea. The “Russian Technique” was the original one used, which consisted of the incisions going from the periphery to the center of the cornea. This was later referred to as the “American technique.”

During the 1980’s RK was very popular, as it was considered to be one of the most refractive surgical studies at the time. The data on it was published every 10 years referred to as PERK study, which stood for (Prospective Evaluation of Radial Keratotomy). This had proven that the progressive hyperopia was usually found after a decade from the time of the original surgery, and the reason is because of the continuous flattening that happens to the central cornea. There is the hexagonal incision that can be made in the periphery, which is referred to as the Hexagonal Keratotomy (HK), which Antonio Mendez, from Mexicali, Mexico describes as a way to correct Hyperopia of lower degrees. The idea of HK is to have six incisions made into the peripheral to form a hexagon that goes in a circle, surrounding the central cornea, and it steepened the hyperopic flat area, and to have the rays of light focus on the retina more precisely. There are two different incisions available to use, they are the connecting and the non-connecting. There are different types that RK can be performed with, as well as different patterns of incisions, and numbers. The number of incisions can be as little as 4, and as many as 32. With orientations being based on the refractive errors, surgeon training, and surgeon style. Many patients may have already had incisional surgeries, with the incisions being placed where the steepest points are located as this relaxes those with astigmatism.

Once reaching the age where presbyopia begins to occur, many will also begin to develop cataracts. There is still hope for one’s vision is still able to be restored by having Epi-LASIK, photorefractive keratectomy, LASIK lens extraction, and phakic lens extraction.

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