| LASIK - LASER IN SITU KERATOMILEUSIS |
ANATOMY OF EYE
There are 3 basic Layers in eye:
(1) CORNEA - Although it appears black or brown according to eye colour, it is actually transparent. It is 1/2 mm thick & has 5 layers. It provides 2/3rd of focusing power of the eye. This is the layers where LASIK is performed.
(2) LENS - It is the middle layer of the eye which has focusing capability like lens of a camera. It is biconvex, clear & transparent. When it becomes opaque it turns into a cataract.
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(3) RETINA - The innermost, thinnest & most delicate layers of the eye which is responsible for transmitting External light signal to the optic never & further to the brain to achieve clear vision.
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NORMAL EYE:
Rays of Light from far get deviated by cornea and Lens & finally come to a point focus onto the Retina. |
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MYOPIC EYE:
Rays of light from far objects come to a point focus in front of Retina. One requires concave (minus) glasses to correct this error. |
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HYPERMETROPIC EYE:
Rays of light from objects come to a point focus behind the eye. One requires convex (plus) glasses to correct this error. |
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ASTIGMATISM:
Rays of light undergo irregular deviation inside the eye & form a focal line instead of a point on the Retina. One requires cylindrical glasses to correct this error. |
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PRESBIOPIA:
Near point of the eye recedes back due to poor contractile power of the internal eye muscles & Increased rigidity of the lens. One requires (plus) convex glasses to correct this for near vision.
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How does the laser work?
The laser is state-of-the-art shaping device which works with an accuracy at 1/2000th of a mm. The corneal surface is polished with a pre calculated & pre programmed laser. This induces a change in refractive power of cornea. Appropriate reshaping can eliminated the Refractive error of the eye. The laser used is EXCIMER laser.
How is the treatment done?
An automated device called as Microkeratome is used to make a horizontal section of cornea to fashion a hinged flap. This flap is lifted so as to expose deeper layers of cornea where reshaping is done with excimer laser. The flat is then replaced back where it sticks to the reshaped corneal bed.
What is the anesthesia used?
Normally the treatment time is 5 - 7 minutes per eye. Hence topical drops are sufficient which make eyes pain free for 15 - 20 minutes. The actual time for delivery of layer is 1 - 2 minutes. No injections are required before or after procedure.
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Is the treatment painful?
Not at all. Although some patient may experience stretching sensation or pressure discomfort during the procedure. One may get pain within 1st 36 hours of procedure due to healing response. Any pain killer tablet can reduce this pain.
Does the patient need to stay in Hospital?
No. The patient needs to wait for 20 -30 minutes after the procedure so as to observe the initial response & then the patient can go home.
Post Operative Schedule:
(1) Put on sunglasses for protection & do not use any irritant.
(2) Hair bath is permitted after 2 days.
(3) Put drops as instructed i.e. Antibiotic & anti-inflammatory drops for 4 - 7 days & Tear replacement drops for 1 - 3 months
(4) Do not swim/ splash tap water directly in the eyes for 3 months.
(5) Avoid make up around the eyes for 1 month.
(6) Resume work the next day. |
How safe is the treatment?
Extremely safe. Besides safety, the other advantages are reliability & short duration of treatment. Around one million people are expected to undergo this treatment in the current year. When the doctor & patient co-operate well during the treatment, there are hardly chances of complications to arise.
Is there a chance of number coming back?
No. The healing process takes around 4 - 6 weeks. During which the number may fluctuate slightly. After this period there is very little chance of getting the number back.
Age limit:
Lower age - 17 or above. In exceptional circumstance, LASIK can be done in young children too.
Upper age - no limit provided there is no cataract.
How much number can be removed?
This depends upon the thickness of cornea.
Myopia: -1d to -15d
Hypermetropia: +1d to +7d
Astigmation: Up to +7d |
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What is new in LASIK?
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CUSTOM LASIK:
A specialised instrument called Aberrometer is used to map the micro irregularities present on the corneal surface. These irregularities are then neutralised by polishing the surface of the cornea with a specialised WAVEFRONT GUIDED LASIK. The vision achieved by this procedure is usually better than glasses. |
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FEMTOSECOND LASIK:
Instead of using Microkeratome to make the Lasik flap, a LASER is used. This makes the entire treatment BLADE FREE. The visual results achieved are similar to the custom Lasik but safety is better. The treatment cost is almost doubled since two different Lasers are used. |
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PRESBYLASIK:
This procedure incorporates software to treat NEAR VISION GLASSES. The concept is to change corneal shape into a multifocal cornea. The safety and stability of this procedure is far better as compared to the older procedure of CK. This procedure is not clinically available as yet. |
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