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Laser Eye Surgery
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| Main Resource Page | Diabetic Retinopathy - Vitrectomy
Laser Eye Surgery - [LASIK: (Acronym for Laser in-Situ Keratomileusis)]
The goal of LASIK is to reduce dependence on corrective lenses. It may not always create 20/20 or better vision. LASIK surgery uses lasers to reshape the top layer (10%) of the eye orbit. This allows images to focus correctly on the retina. The technologically advanced laser equipment is precise and safe for treating nearsightedness, farsightedness and astigmatism.
Some eye surgeons employ trackers (Active Trak 3-D Eye Tracker or similar) cameras to follow the tiniest motions of the eye in all three dimensions.
Laser Vision Correction was first performed using a procedure called photo-refractive keratectomy or PRK. PRK has undergone much advancement since 1995 (when laser eye surgery was first approved by the FDA). Vision correction with PRK is accomplished by removing tissue from the surface of the cornea, using Laser-inSitu Keratomileusis - LASIK - the most popular form of laser vision correction. It does this by removing tissue from the inner cornea.
A variety of manufacturers provide the equipment for the surgery, IntraLase, CustomVue, Alcon LadarVision, etc. WaveScanTM Technology is a digital technology originally developed for use in high-powered telescopes to reduce distortions when viewing distant objects in space.
Light travels in a procession of flat sheets known as wavefronts. Gentle wavefront lights enter the eye, pass through the optical system (cornea, lens, and retina) and are then reflected back into the wave sensors. It compares the reflected wavefronts with the original unaltered wavefronts. This process produces a fingerprint of vision (mapping). The information is transferred to a laser and is used as a guide to reshape the cornea during the laser vision treatment.
Step by Step Process:
1. The patient must be a good candidate for LASIK. The workup includes corneal topography.
2. Anesthetic drops are placed in the eye and the patient is escorted to the laser room and positioned on a reclining chair. The area around the operative eye is prepped to ensure sterility. A drape is placed over the eye and a small device inserted to keep the eyelids open to prevent blinking.
3. The operator uses a microkeratome and the laser. The suction ring of the microkeratome is placed on the eye to immobilize the eye during the procedure. It is then used to create the flap and the flap is retracted. The operator then aligns the laser with the patient’s eye. The patient is instructed to fixate on the blinking light.. The laser is started (the patient hears a clicking sound). It is used for approximately 30 to 60 seconds. At the end of the procedure, the flap is repositioned and adheres to the cornea.
4. A slip lamp is then used to examine the eye. Eye drops are instilled and a clear plastic shield placed over the eye.
5. Post surgery, the patient is instructed to keep the eyes closed as much as possible for the first 12 hours.
Usually there is no pain involved in the postoperative period and vision starts to improve within hours. With any over or under-correction, additional procedures may be used to enhance the results.
One of the most troublesome aspects of laser vision correction has been the relatively poor night-time vision that some patients experience. Poor night vision may be the result of the treatment area being too small in relation to the size of the fully dilated pupil (your pupil dilates – enlarges – when you go into the dark).
It is essential to have an accurate way of measuring the pupil size in the dark. If you shine a light onto the eye to measure the pupil size, then the pupil gets smaller in response to the light, and you are not measuring the true maximum size of the pupil.
Pupillometers are used to measure pupil size in the dark. This device uses light amplification technology to allow an accurate assessment of the pupil size. More and more accurate devices are now available to do that, one of the latest being the Procyon . This computerized device makes ten different pupil size measurements at each of three different light levels, and uses imaging software to precisely assign a size to each measurement. This has taken pupil size determination to a much higher level.
SURGICAL COMPENDIUM...
For those who are interested, samples of eye surgery (dictation/reports) are available in our Surgical Compendium eBook
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