Laser corrective vision surgery
Clarity of vision depends upon how well cornea and lens permit rays to fall on to the retina on cones and rods. Light rays refract and bend on to focus on to the retina to form a clear image. There are two photoreceptors cones (which color sensitive) and rods (which is dim light sensitive).
These send signals to brain though optic nerve. If the shape of the cornea is abnormal light does not fall properly or proper image is not formed on the back of cornea. (Fletcher, 2007) This is called refractive error.
This can be corrected by refractive surgery. Refractive errors include myopia (nearsightedness), hyperopia (farsightedness), astigmatism (an irregularly shaped cornea which causes blurring), and presbyopia (similar to hyperopia, a condition which causes the lens to harden). Refractive eye surgery helps to reduce or eliminate a person’s dependency on eyeglasses or contact lenses. (NYP, 2007) There are several types of refractive surgery; proper diagnostics can only determine which is needed by whom.
It can well be stated that “compared with surface ablation, LASIK results in earlier and faster improvement of uncorrected visual acuity, and has less (or almost no) postoperative discomfort, improved stability, and predictability.” (Agingeye, 2007) At the same note it can also be stated that “with LASIK, however, the risks of flap-related complications (wrinkles, debris, folds, buttonhole, and diffuse lamellar keratitis) may be associated with the creation of the lamellar flap.” (Agingeye, 2007)
Precautions of laser correction surgeries are
1) Eyes should be healthy
2) Patient should be adult
3) Stable vision for a year or so.
4) If pregnant surgery should be performed on after evaluating the shape of corneas.
5) Should not have Degenerative or autoimmune diseases. (Allaboutvision, 2007)
Some of risks in LASIK are
1) Some patients lose vision
2) Some patients develop debilitating visual symptoms.
3) irregular astigmatism, which can decrease the corrected vision
4) corneal haze or glare
5) overcorrected or undercorrected vision
6) inability to wear contact lenses in the future
7) loss of the corneal flap, requiring a corneal graft
9) infection (Roberts, 2007)
10) vision loss
11) develop severe dry eye syndrome
12) Irregular Astigmatism
14) Night Vision Problems or Night Glare and Halos
15) Central Islands
16) Epithelial Ingrowth
Diffuse Lamellar Keratitis (DLK) (Banerjee, 2005)
Lasik has its benefits too. It is performed under a protective layer of corneal tissue. As a result, there is less surface area to heal, less risk of scarring, less risk of corneal haze, less postoperative discomfort, less postoperative need for medications, and vision returns more rapidly, often within a day or so. It can an also treat a higher range of vision errors. (Grochmaleye, 2007)
One testimony to this is available from the US military. It is stated that “the U.S. military also has adopted widespread use of refractive surgery including LASIK to decrease reliance of troops on artificial lenses or eyewear as evidenced by the more than 16,000 U.S. Army personnel who underwent refractive surgery from 2000 through 2003. Studies of these outcomes showed that 86% achieved 20/20 or better uncorrected vision and 98% achieved 20/40 or better, which legally is considered good enough for driving without eyewear or contact lenses.” (Allaboutvision, 2007)
Some Statistics are in this context can be stated as follows:
Patient Results Three Months After Treatment
20/20 or Better
20/40 or Better
LASIK for myopia
42.0% to 84.8%
76.8% to 99.4%
LASIK for hyperopia
48.8% to 58.3%
93.4% to 98.3%
PRK for myopia and hyperopia*
In conclusion it can be stated that the method has both positive and negative aspects. It should be remembered that the use of laser was approved by the FDA’s Medical Devices Advisory Committee in the context of the Ophthalmic Devices Panel and the effectiveness and safety was proved with the help of various clinical studies. (FDA, 2007)
The FDA evaluated several case studies on the method and after analysis of 1,013 eyes LASIK performances that was carried out in thirteen centers of medicine over the period of half year it was found that “of the 1,013 eyes treated, 92 percent were corrected to 20/40 or better and 47 percent were corrected to 20/20 or better without glasses or contact lenses.” (FDA, 2007) However, in accordance to FDA it could be stated that “short-term side effects included pain (for 24 to 48 hours), corneal swelling, double vision and light sensitivity. In some patients these effects lasted for several weeks.”(FDA, 2007) Thus this could be termed as a well tested process but it needs more time and application to become a complete water-tight method. It could be stated that more work on the subject is necessary.
American Academy of Ophthalmology; (2007); Ophthalmology Report 2007; Sydney: Allied Publications
Allaboutvision; (2007); Lasik Criteria; allaboutvision.com; retrieved on 10.02.2008 from http://www.allaboutvision.com/visionsurgery/lasik-criteria.htm
Allaboutvision; (2007); Lasik complication; allaboutvision.com; retrieved on 10.02.2008 from http://www.allaboutvision.com/visionsurgery/lasik_complication_1.htm
Banerjee, D; (2007); Details from Medical Journals of AIIMS; New Delhi: AIIMS
Fletcher, R; (2007); Medical Principals: Beliefs and Knowledge; Believing and Knowing; Dunedin: Howard ; Price
Grochmaleye; (2007); Lasik benefits; grochmaleye.com; retrieved on 10.02.2008 from http://www.grochmaleye.com/lasik_benefits.html