Procedure of a Lasik Surgery - Essay Example

LASIK1 is used to treat a variety of vision problems, including myopia2, astigmatism, and hyperopia.3 In all these cases the eye is healthy, but deformed so that the light entering the eye is not focused on the retina. In theory, adjusting the shape of the cornea should compensate for the misshapen globe. The first step in a LASIK procedure is an antibiotic and anesthetic. Both are topical treatments; applied directly to the eye. An apparatus is placed on the eye to keep it wide open during the surgery. A trephine, a circular marker, is placed on the eye to show precisely where to replace the flap of cornea tissue one the ablation has been performed. Doctors also put a pneumatic suction ring on the eye and intraocular pressure is raised to about 65mmhg which prevents the eye from rolling around in the patient's head. The doctor then uses a microkeratome4 or a femtosecond laser to cut a three-sided flap in outer layer of the cornea. The cut is between 100-180 microns deep depending on the patient and includes the epithelium and Bowman's Membrane. The flap is pealed back to reveal the stromal layer and an excimer laser 5 beam is used to remove part of the cornea, thereby reshaping it. This process is known as ablative photo-decomposition. The flap is then folded back onto the eye and will self-adhere to the remainder of the cornea. The convalescence period is generally 3-6 months. Study after study proves the overall safety and effectiveness of LASIK. In a 1996 study involving 62 severely myopic eyes, the LASIK procedure improved the mean refraction from -14.80 D to -1.7 D.6 The mean regression7 of myopia was just -.2 D (Knorz, et al, 1996 a). Another study shows similar results for moderately myopic eyes. In this instance LASIK surgery improved the mean refraction of the eyes from -14.3 D to -1.4D (Knorz, et al, 1996 b). In hyperopic eyes, results were similar. A 2005 study of 139 hyperopic eyes shows that LASIK improved mean spherical refraction from 2.39 +/-.99 D to -.05+/- .61 D. Ninety-one percent of eyes in that study were corrected to within +/-.5 D of emmetropia 8(Jin, et al, 2005). It appears that LASIK surgery may not be appropriate for those people who are severely hyperopic. For a 1998 study, researchers grouped subjects together based on their degree of hyperopia; group A with 2D or less, group B between 2 and 3D and group C greater than 3D. After 6 months, 100% of cases in group A and 95.3% of the cases in group B were within +/-1.0D of emmetropia. However, LASIK improved vision to this degree in only 71.4% of the eyes in group C (Argento & Costino, 1998). There are some troubling side-effects that are common among people who have had LASIK surgery. A meta-study published in the European Journal of Medical Research found that over-correction, under-correction and regression occurred in patients 24% of the time and the hazy vision occurred in 15% of post-operative LASIK patients (Lamparter, et al, 2005). One study undertaken in Japan shows that LASIK had over a 95% effectiveness rate but that in 10.5% of the cases, there was hemorrhage of the corneal limbus during surgery. DLK, a condition in which the cornea begins attacking itself, occurred in 2.3% of the eyes. .04% of the eyes studied developed an infection and epithelial in-growth occurred in .1% of the eyes (Sun, et al, 2005). Many smaller studies bear out the findings of the meta-studies. According to a study performed by Robert T. Lin and Robert T. Maloney, the flap of cornea did not heal properly after LASIK 8.6% of the time (Lin & Maloney, pg 129). Another common complication is the development of dry-eye. A 2005 study showed that among Caucasians, LASIK surgery increased the incidence of chronic dry-eye from 5% to 7% of the population (Albeitz, et al, 91). Some complications of LASIK, such as over-correction, under-correction haziness and regression, result in the surgery having to be performed again. The literature shows that performing a second LASIK surgery is safe and generally have good outcomes. Agarwal et al. studied the results of 29 patients/50 eyes with mild myopia that needed a second LASIK surgery to enhance the first. The researchers reported that the average residual refraction was -4.3 +/- 1.83 D. A year after the second surgery, the average residual refraction among the subjects was -.45 +/- .68D. Thirty-one of the 50 eyes were emmetropic, 13 more eyes were within +/-1D of emmetropia and 5 more eyes were within +/- 2D of emmetropia. The researchers reported that the mean uncorrected visual acuity improved from 20/80 to 20/40. Most importantly, not one patient developed a severe complication such as free cap or flap irregularity. LASIK is a fairly new procedure and as such there is not much literature about long-term side-effects. One study at Emory University looked at donated corneas that had the LASIK procedure performed to check the wounds. They found that different sections to the cornea membrane heal at different rates. The researchers found that any additional LASIK procedure on the same eye could be performed up to 8.4 years after the initial surgery (Schmack et al, 2005). From a psychological standpoint, evidence suggests that people who want the surgery and go through with it have a higher quality of life than those who wanted the surgery but did not get it. The average score on the questionnaire designed for the study, rose from an average of 40.07 +/- 4.30 to 53.09 +/- 5.25. However, a small number of patients, 4.5% according to this particular study, had lower assessment scores after the procedure. The study found that women especially benefited psychologically from the surgery. It should be noted, however, that, "people presenting for LASIK scored measurably poorer than matched patients not contemplating refractive surgery" (Garamendi, et al, 2005), perhaps indicating that people who are attracted to LASIK are, generally speaking, unhappier than those who have not seriously considered having the procedure. PRK9 is an alternative laser eye surgery that was more common in the United States before LASIK was approved by the FDA. LASIK has replaced PRK in most instances. Instead of creating a flap and ablating the cornea tissue below the flap, doctors performing PRK use an excimer laser, also set to 193 nm, to sculpt an area on the cornea between 5 and 9 millimeters in diameter. The sculpting can remove anywhere from 5%-30% of the thickness of the cornea depending on how severe the patient's myopia is. PRK used to be more common, but has lost popularity over the years because in most cases LASIK produces better results and fewer complications. A 1996 study published in the Journal of Refractive Surgery shows that among moderately myopic eyes (between -6D and -10D), LASIK had a greater success rate. After one year, just 39% of those eyes treated with PRK were corrected to within +/-1D of emmetropia. LASIK, on the other hand, corrected 60% of the eyes to +/- 1D of emmetropia. Furthermore, these researchers report that none of the LASIK patients developed corneal haze while 90% of the PRK patients did develop that condition. LASIK has proven itself over and over again to be safe, effective and an improvement over older vision-correction procedures. Since LASIK was approved in the United States in 1997, about 5 million people have had the procedure . Although the percentages of LASIK surgeries that have complications are low, this means that even if only .5% of eyes suffered from any sort of complication or side-effect, 500,000 eyes would be affected. As with any medical procedure, LASIK could be detrimental; requiring costly medications, cumbersome treatments, and sometimes even causing blindness. A person must carefully consider if he/she is willing to risk these consequences to be free of glasses and contact lenses. Bibliography Agarwal, A; Agarwal A; Agarwal T; Agarwal A, Agarwal S. (2001) "Laser in situ Keratomileusis for Residual Myopia after Primary Lasik." Journal of Cataract Refractive Surgery 27 97) 1013-1017. Albietz, J; Lenton, L;McLennan,S. (2005) "Dry Eye After LASIK: Comparison of Outcomes for Asian and Caucasian Eyes." Clinical and Experimental Optometry 88 (2) pg 89-96. Buxey, K. (2004) "Delayed Onset Diffuse Lemellar Keratitis Following Enhancement LASIK Surgery." Clinical and Experimental Optometry 87(2) pgs 102-106. Doane, JF; Koppes, A; Slade, SG (1996) "A Comprehensive Approach to LASIK." Journalof Opthalmic Nursing Technology 15 (4) 144-147. Feltham, M; Wolfe, R. (2000) " Some Variables to Consider to Avoid the Need for LASIK Surgical Enhancements." Clinical and Experimental Optometry 83(2) pgs 76-81. Helmy, SA; Salah, A; Badawy, TT; Sidky, AN. (1996) "Photorefractive Keratectomy and Laser in situ Keratomileusis for myopia between 6.00 and 10.00 Diopters." Journal of Refractive Surgery 12(3) pgs 417-421. Garamendi, E; Pesudovs, K; Elliott, DB (2005) "Changes in Quality of Life After Laser in situ Keratomileuis for Myopia." Journal of Cataract Refractive Surgery 31(8) 1537-1543. Jin, GJ; Lyle, WA; Merkley KH. (2005). "Laser in-situ Keratomileusis for Primary Hyperopia." Journal of Cataract Refractive Surgery 31(4) pgs 776-784. Knorz, MC; Liermann A; Seiberth V; Steiner, H; Wiesinger B. (1996) "Laser in Situ Keratomileusis to Correct Myopia of -6.00 to -29.00 diopters." Journal of Refractive Surgery 12(5) pgs 575-584. Knorx, MC; Liermann, A; Wiesinger, B; Sieberth V, Lisenhoff, H (1996) "Correction of Myopia Using Laser In Situ Keratomileusis." Klin Monatsble Augenheilkd 208(6) 438-445. Lamparter, J; Dick, HB; Krummenauer, F. (2005) "Clinical Benefit, Complication Patterns and Cost Effectiveness of Laser in situ Keratomileusis (LASIK) in Moderate Myopia: Results of Independent Meta Analyses on Clinical Outcome and Postoperative Complication Profiles. European Journal of Medical Research 10(9) 402-409. Lin, R; Maloney, R. (1999) "Flap Complications Associated with Lemellar Refractive Surgery." American Journal of Opthamology 127 (2) pgs 129 136. Sun, L; Liu, G; Ren, Y; Li, J; Hao, J; Liu, X; Zhang, Y. (2005) "Efficacy and Safety of LASIK in 10,052 eyes of 5,081 myopic Chinese. Journal of Refractive Surgery 21 (5) 633-655. Schmack, I; Dawson, DG; McCarey, BE; Waring, GO; Grossniklaus HE; Edelhauser, HF. (2005) "Cohesive Tensile Strength of Human LASIK wounds with histologic, Ultrastructutal,, and Clinical Correlations." Journal of Refractive Surgery 21 (5) 433-445. Read More