LASIK or laser-assisted in situ keratomileusis is a form of eye surgery which is able to cure myopia, hyperopia as well as astigmatism. All LASIK surgeries make use of the latest technology to alter the shape of the cornea in the eye by removing, shrinking or expanding tissues in the eye to solve these problems. Today, many people resort to LASIK eye surgeries to solve their eye problems so that they would not need to wear glasses or contact lenses since it is a nuisance in our daily lives. However, there are many types of LASIK eye surgeries which are targeted to different medical disorders, make use of different tools and involve different set of side-effects. The main issue is that many people are not fully aware of the risk they are taking when undergoing a LASIK surgery, hence, putting themselves in potential danger. There are mainly 5 LASIK surgeries, namely Automated Lamellar Keratoplasty, Photorefractive Keratectomy, Laser Thermal Keratoplasty, Conductive Keratoplasty, Radial Keratotomy.
Surgeries
Automated Lamellar Keratoplasty
Function
This surgery solves severe levels of myopia or mild levels of hyperopia.
Procedure
Firstly, the doctor calculates the shape to cut according to the patients eye(s). The eye is then anesthetized and a ring is fixed so that it remains opening. A microkeratome is then used to incompletely cut a thin flap of cornea so as to expose the layer of tissue below . Then, the microkeratome is used again to carve the right shape in the cornea so as to change the shape of the eye lens. The flap is then replaced for it to heal.
However, if the patient is hyperopic, the flap is replaced back without removing anything. This is because the cornea stiffens during recovery.
This operation usually takes less than an hour.
Recovery
Just 24 hours after the operation, patients are almost healed and able to see clearly. Besides, patients may feel very comfortable after the surgery although it may take months to regain vision stability. Ideally, the patient will have perfect vision after the surgery.
Possible Side-effects
Glare, inability to wear contact lenses, infections, corneal scarring, over or under-correction, inflammation can be the side-effects of Automated Lamellar Keratoplasty when the surgery is not done properly.
Pros and Cons
Automated Lamellar Keratoplasty is able to cure both myopia and hyperopia. Also, it only requires 24 hours for the cornea to heal after surgery. However, the risks taken when undergoing this surgery is high as it may lead to inflammation, infections and corneal scarring which may result in permanent, incurable and serious effects on the patients eye. Moreover, the time taken for the surgery is very long.
Photorefractive Keratectomy
Function
This surgery solves myopia, hyperopia as well as astigmatism. However, this surgery is best suited for patients with myopia and most patients would take this surgery so that they would not need to wear spectacles or contact lenses.
Procedure
The ophthalmologist will firstly execute a refraction to ensure the refractive alteration the surgeon will instruct the excimer laser is right. After the eye is numbed, the surgeon places a speculum in the eye to keep the eyelids apart and disallow movement. The patient stares at the twinkling light of a laser microscope and must keep his gaze steady on that light, staying motionless at the same time. After the the laser co-ordinatesis double checked, the eye surgeon takes away the epithelium with a sponge, mechanical blade, or the excimer laser. With the epithelium totally taken away, the surgeon will start reconstructing the cornea.
The whole process is approximately 10 minutes.
Recovery
A bandage contact lens would need to be worn on the treated eye to protect it and allow the healing process to take place; it also eases some of the pain of the exposed cornea. Anti-inflammatory and antibiotic eye drops needs to be applied to stop infection and reduce pain.
Possible Side-effects
If the surgery is not done properly, patients may experience glare, vision fluctuation, development of irregular astigmatism, vision distortion (even with corrective lenses), glaucoma, loss of best visual acuity, and, though extremely rare, total vision loss. A more common side-effect is long-term haze as it is resulted by aggressive healing processes which form corneal scars.
Pros and Cons
Although this surgery takes only a short time and is able to solve myopia, hyperopia as well as astigmatism, the patient is at a high risk of having long-term haze which would be a burden when we use our eyes. Also, total vision loss may also occur in extremely rare cases.
Laser Thermal Keratoplasty
Functions
Laser Thermal Keratoplasty is only able to help patients with mild hyperopia
Procedure
A Holmium laser (an infrared laser that emits heat to reduce the size of the corneal tissue) is used to reshape the cornea for low ranges of hyperopia. It is then used to heat the stromal collagen in a circle around the outside of the pupil. The heat results in the tissue becoming much smaller, forming a tightening effect. The side of the cornea is then pulled, causing the center to protrude. Because the cornea of a farsighted eye is too flat, this bulging effect, when carefully controlled, corrects the problem.
Recovery
After LTK surgery, subsequent appointments are needed for the very next day and for one week, one month, and 3-6 months after the procedure. An object in your eye may be felt for the first 24 hours following LTK. Eye drops can help relieve this, but only to a certain extent. Light sensitivity may also be felt for the first 24 hours and sunglasses may be advisable.
Possible Side-effects
There aren’t any serious side-effects to the Laser Thermal Keratoplasty as it is done using laser to change the formation of the cornea. The most common, mild side-effect would be over and under-correction which could be solved easily through another minor surgery.
Pros and Cons
Although this surgery is only able to cure mild hyperopia, causes much irritation to the eye during the first 24 hours and requires the patient to constantly revisit the doctor for checking, it is extremely safe compared to the other surgeries as the side-effects involved are not serious and can be solved easily.
Conductive Keratoplasty
Function
This surgery solves mild hyperopia and astigmatism. Most elderly undergo this surgery so that they do not need glasses when reading.
Procedure
A corneal topographer first maps the curvature of the eye. The eye is then anesthetized and a speculum is used to prevent the eye from blinking. After the treatment pattern is imprinted, a hand-held instrument with a tiny probe would then apply low-level radio frequency energy to the specific spots that form a circular pattern on the outer part of the cornea to a specific depth.The connective tissues in this area would then shrink causing the circular band to act like a belt that "tightens" and steepens the cornea, hence, changing curvature of the eye's surface.
The entire process last a few minutes
Recovery
There is no recovery period for this surgery as no tissue is removed from the eye; hence, no healing is required.
Possible Side-effects
The only side-effect is that the distant view of the patient might be affected to a minor extent. That is why doctors recommend patients who undergo this surgery to have good distant vision. However, if the patient has presbyopia, the condition of the eye may worsen after time. That is why doctors go through thorough checks to ensure that the patient does not have presbyopia.
Pros and Cons
This surgery last only a few minutes, does not require any form of recovery, does not remove any tissue from the cornea and has only one minor side-effect. However, the result might not be ideal if the patient were to have presbyopia, hence, doctors need to be cautious when allowing patients to undergo this surgery.
Radial Keratotomy
Function
Radial Keratotomy cures mild myopia and astigmatism. Patients should not have pathological myopia and degenerative changes caused by severe myopia, such as retinal tears or disease of the cornea, should not be present.
Procedure
The eye is anesthetised and a ring is fixed to it in order to prevent if properly positioned and flat. A precision calibrated diamond knife is used to make four to eight incisions perpendicular to the circumference of the cornea. To achieve high efficiency, the incisions usually reach deep into the cornea. This will cause the cornea to flatten and thus change the shape of the lens.
Recovery
Radial Keratotomy causes more discomfort and requires a much longer time to heal as compared other surgeries. The results are also more unpredictable. However, the incisions are suspected to never heal entirely. There have been reports of unhealed incisions even after 20 years of surgery. Patients have to return to doctors frequently for the first year in order to prevent these inflammation and infections to occur in the unhealed cornea.
Possible Side-effects
An improperly carried out surgery may lead to infection, inflammation, glaucoma, puncture of the cornea, loss of fine depth perception and more scattering of light.
Pros and Cons
Radial Keratotomy involves many serious side-effects including inflammation and infection. It is also troublesome as it requires the patients to revisit the doctor constantly within a year to prevent these side-effects from surfacing. Because this surgery is done by using a diamond knife, it may lead to unpredictable results if not carried out properly.
Research
Final refined research questions:
What are the best surgeries to be used when setting up a LASIK centre?
Which surgeries provide the least risks of having side-effects to the patients?
Which surgeries is less of a burden to the patients during recovery period?
Which surgeries are able to solve the most common eye problems?
Solution:
Choice
For setting up a LASIK centre, we have decided to use only Conductive Keratoplasty and Laser Thermal Keratoplasty among the five surgeries.
Side-effects
For Conductive Keratoplasty, the only side-effect is that the distant view of the patient might be affected to a minor extent. Although if the patient has presbyopia, the condition of the eye may worsen after time, this can be easily avoided through thorough medical check of the patient beforehand.
For Laser Thermal Keratoplasty, there aren’t any serious side-effects as it is done using laser to change the formation of the cornea. The most common, mild side-effect would be over and under-correction which could be solved easily through another minor surgery.
For the other surgeries, Automated Lamellar Keratoplasty and Radial Keratotomy involve side-effects such as infection and inflammation which is very serious and lethal to the eye. Especially when infection and inflammation may lead to eye diseases like retinitis pigmentosa which are incurable it should be avoided. As for Photorefractive Keratectomy, there is a high risk of having long-term haze which would be a burden when we use our eyes. Also, total vision loss may also occur in extremely rare cases.
Recovery
Conductive Keratoplasty requires no recovery at all since no tissue is removed from the cornea.
Laser Thermal Keratoplasty would only cause irritation to the eye for one day after surgery although it requires the patient to visit the doctor frequently for checkups for six months.
Automated Lamellar Keratoplasty patients would feel uncomfortable after the surgery and it may take months to regain vision stability. For Photorefractive Keractectomy, a bandage would need to be worn and anti-inflammatory and antibiotic eye drops needs to be constantly applied to the eye after surgery. Radial Keratotomy causes much discomfort and the eye might remain unhealed even after 20 years. The patient would even need to visit the doctor regularly for one whole year after sugery.
Functions
Compared to the other three surgeries, Conductive Keratoplasty and Laser Thermal Keratoplasty are able to solve only hyperopia and astigmatism but not myopia.
Summary:
Overall, Conductive Keratoplasty and Laser Thermal Keratoplasty is still the best choice although both are unable to cure myopia because the risk involved in both surgeries are much lesser and less serious than other surgeries and the it does not bring much problems to the patient during recovery stage compared to other surgeries too.
Eligibility
- Pregnancy
- Breast-feeding
- Very small or very large refractive errors (Myopia up to -15.00 diopters, astigmatism from -0.50 diopters to -4.00 diopters and hyperopia from +1.00 diopters to +5.00 diopters are allowed)
- Scarred corneas
- Macular Disease
- Autoimmune disease
- Diabetes
- Glaucoma
- Persistent blepharitis
Statistics of LASIK
- Around 30 patients per week per centre
- 80% of the patients were satisfied with their surgery
- 53% experince at least one side-effect
- 22% experinced side-effects which lasted more than 6 months
Definitions
Cornea- Clear structure that covers the front part of the eye. The cornea provides most of the eye’s optical power, while the crystalline inner lens, located behind the iris serves to “fine tune” the focus of the images.
Collagen- In referring to the eye, collagen is the protein fibrils within the corneal tissue that help sustain its shape. Some new refractive vision correction procedures heat these fibrils with a special laser causing them to shrink and change the shape of the cornea.
Myopia (nearsightedness)- The front curvature of the cornea is too steep in a nearsighted person, causing good reading vision but poor distance vision.
Pathological Myopia- Also known as degenerative myopia is characterized by marked fundus changes and associated with a high refractive error and subnormal visual acuity after correction. This form of myopia gets progressively worse over time.
Hyperopia (farsightedness)- Vision that results when there is too short a distance from the cornea to the retina. This can be caused by an eye that has a vertical oval shape or a cornea that is flatter than normal.
Presbyopia- Deterioration in the ability of the eye’s natural crystalline lens to expand or contract in order to focus on close objects.
Astigmatism- Uneven curvature of the cornea in which refractive light rays are bent out of focus resulting in distorted vision. Those people with astigmatism are usually born with the disorder and it does not worsen with age. Often occurs in conjunction with nearsightedness or farsightedness.
Glaucoma- Condition caused by excessive buildup of fluid inside the eye putting pressure on the retina. Glaucoma has few if any symptoms, but a simple, painless eye test detects the problem. If untreated, glaucoma can result in gradual, painless, irreversible loss of vision.
Inflammation- Redness, swelling, pain, tenderness, heat, and disturbed function of an area of the body, as a reaction of tissues to injurious agents.
Retinal- A form of vitamin A called retinal is responsible for transmitting light sensation in the retina of the eye. Deficiency of vitamin A leads to night blindness.
Macular Disease (Macular Degeneration)- Degeneration of the photoreceptors in the macula or central region of the retina. This area of the retina is responsible for central vision, used for reading, seeing faces, and so on. Often associated with aging.
Autoimmune- Of or relating to an immune response against one of the body's own tissues or cells.
Diabetes- Any of several disorders characterized by increased urine production.
Blepharitis- Common, persistent and sometimes chronic inflammation of the eyelids, resulting from bacteria that reside on the skin. Blepharitis is usually only a minor irritation.
Holmium Laser- Infrared (thermal) laser which its beam is cool and can remove small areas of tissue without affecting surrounding tissue. The Holmium laser is used to shrink the peripheral area of the cornea in order to make its shape steeper and correct mild to moderate cases of farsightedness. The laser works when moisture in the cornea absorbs energy from the laser pulses causing corneal tissue to heat up and shrink.
Microkeratome- Sophisticated surgical device used to shave a very thin amount of the cornea at a predetermined depth. Used to create the corneal “flap” which is lifted.
References
http://dictionary.reference.com/browse/inflammation?r=75 http://en.wikipedia.org/wiki/Myopia http://dictionary.reference.com/browse/autoimmune?r=75 http://dictionary.reference.com/browse/diabetes http://www.allaboutvision.com/visionsurgery/ck_ltk_eye_surgery.htm http://www.webmd.com/eye-health/radial-keratotomy-rk-for-nearsightedness http://www.docshop.com/education/vision/refractive/other-treatments/ http://www.lasikcomplications.com/RK-radial-keratotomy.html http://en.wikipedia.org/wiki/Radial_keratotomy http://www.healthcentre.org.uk/laser-eye-surgery/laser-thermal-keratoplasty.html http://www.visionrx.com/Library/enc/enc_ltkeratoplasty.asp www.visionrx.com/library/.../innov_laser_thermal.asp http://www.youreyeguide.co.uk/ltk/ltk-sideeffects-aftercare.html http://www.urologicinstituteofnj.com/images/stonesLaser.jpg http://www.visionrx.com/library/enc/tableac.asp http://www.lasikeyesurgerycorrection.com/lasik_risks.html http://www.webmd.com/eye-health/night-vision-problems-halos-blurred-vision-night-blindness
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http://www.eyecare-information-service.org.uk/lasereyesurgery/alk.html http://blogs.consumerreports.org/health/2009/07/lasik-eye-surgery-lasik-survey-getting-the-best-price-for-lasik-survey.html
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