Cornea. 3. Five layers of the Cornea. 4. Refractive Surgery Procedures for the Cornea. 5. Wavescan. 5. PRK. 5. LASIK. 6. Intralase Laser. 6. Lens. 7. Abstract. ○ AIM: To compare the lifetime and annual economic burden of spectacles, contact lenses, and refractive surgery in correction of. INTRODUCTION. Refractive surgery has seen extensive advancements in recent years and has evolved from a rudimentary science a few decades ago to an.
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REFRACTIVE SURGERY. Arturo S. .. CONTRAINDICATIONS: Laser refractive surgery is contraindicated pdf2/portal7.info IOL refractive surgery. □. Compare the pros and cons of various lens- and corneal- based modalities, including presbyopic and toric IOLs. □. Refractive Surgery for Myopia, Astigmatism, and Hyperopia. A fillable PDF form for downloading is available at portal7.info
Uveitis : estimated at 0. Decreased atmospheric pressure at higher altitudes has not been demonstrated as extremely dangerous to the eyes of LASIK patients. However, some mountain climbers have experienced a myopic shift at extreme altitudes. Participants who developed new visual symptoms after surgery, most often developed halos. Up to 40 percent of participants with no halos before LASIK had halos three months following surgery.
Reasons for not performing refractive surgery. J Cataract Refract Refract Surg ; 16 3 — Keratectasia induced by laser in situ keratomileusis in keratoconus. J Surg ; 28 5 — Avoiding serious corneal complications of laser assisted in situ keratomileusis and photorefractive keratectomy.
Ophthalmology ; 4 — Seiler T, Quurke AW. J Cataract Refract Surg ; 24 7 — Dry eye after refractive surgery. Curr Opin Ophthalmol ; 12 4 — Symptoms of dry eye and recurrent erosion syndrome after refractive surgery. J Cataract Refract Surg. Correction of myopia and astigmatism after penetrating keratoplasty with laser in situ keratomileusis. Cornea ; 21 6 — Laser in situ keratomileusis for residual myopia after photorefractive keratectomy. J Cataract Refract Surg ; 28 5 — Hyperopic laser-assisted in situ keratomileusis for radial keratotomy induced hyperopia.
Ophthalmology ; 3 — Management of the corneal flap in laser in situ keratomileusis after previous radial keratotomy. Am J Ophthalmol ; 2 — Laser in situ keratomileusis to correct residual myopia after cataract surgery.
J Refract Surg. Experimental laser-assisted in situ keratomileusis induces the reactivation of latent herpes simplex virus. Am J Ophthalmol ; 4 — Davidorf JM. J Refract Surg ; 14 6 Am J Ophthalmol ; 5 — Possibilities and results of photorefraction operations for myopia after retinal detachment surgery. Vestn Oftalmol ; 5 — Sinha R, Dada T et al. LASIK after retinal detachment surgery. Br J Ophthalmol In Press.
Laser in-situ keratomileusis In: Refractive Surgery: A manual of principles and practice. Patient Education, Assessment and Informed Consent. In: Refractive Surgery: A manual of principles and practice. Stern C. Eur J Med Res ; 9; 4 9 — J Refract Surg ; 12 5 — Ophthalmology ; 9 — Comparison of corneal pachymetry using ultrasound and Orbscan II.
J Cataract Refract Surg ; 28 2 — Rabinowitz YS, Rasheed K. J Cataract Refract Surg ; 25 10 — Comparison of methods for detecting keratoconus using videokeratography.
Arch Ophthalmol ; 7 — Role of Orbscan II in screening keratoconus suspects before refractive corneal surgery. Ophthalmology ; 9 : — Section 2 Equipment and Instrument 5 Excimer Laser Machines Namrata Sharma, Rakesh Ahuja, Rasik B Vajpayee Excimer laser machines generate the ultraviolet Argon-Fluoride nm laser and provide for its optical manipulation, computerized control, and final delivery to the cornea. In order to understand the laser machines, one should understand the fundamental concepts of the excimer laser.
Spontaneous Emission and Stimulated Emission Whenever an electron from a lower orbit moves to a higher orbit, it cannot stay there for too long and hence, it comes back to its original orbit, but in the process, it gives off a photon of light and this is called spontaneous emission.
These photons then hit other atoms leading to the amplification process. Spontaneous emission, nneutron, p-proton, e-electron K-lower orbit, M-higher orbit Excimer laser machines 37 conduct the lasing process. The argon fluoride nm is a pulsed laser which creates an accurate and precise excision of the corneal tissue to an exact depth, with minimal disruption of the surrounding tissue. Its wavelength practically does not heat the tissue but breaks the inter and intramolecular bonds.
The laser pump is the source of energy for the electrons which can be in the form of electrical discharge or current or light energy produced by either flash pumps or other lamps. In order for lasing action to occur, the pumped medium must be in a state of population inversion, i. Excited Dimer Molecules made up of two identical atoms are called dimers.
On dissociation of the excimer argon fluoride , population inversion occurs and this releases the ultravioler laser. Excimer Machine The basic design of an excimer laser machine is shown in Figure 5. Excimer laser usually consists of a large aluminium box which is filled with an appropriate gas mixture.
There are 2 metal electrodes spaced 2 to 3 cm apart to which the energy is sent through the capacitors charged to serve tens of kilovolts. The protective flap is then smoothed back over and stays in place without stitches. SMILE — the surgeon reshapes your cornea through a small, self-sealing hole.
The skin then grows back naturally. All 3 types of laser eye surgery have similar results. Your surgeon will talk through your options with you and help you decide on the most helpful one for you.
Are there any risks? There's usually no extra cost for this. It's a bit like building contact lenses into your eyes. Because the lens is inside your eye, you can do things you couldn't normally do in contact lenses, such as swimming or water sports.
PIOL can be a good option for younger people who aren't able to have eye laser surgery, perhaps because they have a high eye prescription or a high degree of astigmatism. Later in life, RLE may be a better alternative. No stitches are needed. Your surgeon will discuss any side effects and risks with you before you go ahead with surgery.
This article has been cited by other articles in PMC. Abstract Introduction Refractive ophthalmic surgery allows refractive errors to be corrected permanently in a safe, effective, and reliable way with few complications. Methods Selective literature review with special reference to the guidelines of the German Commission for Refractive Surgery.
Results With a total of almost 18 million treatments performed to date, laser in-situ keratomileusis LASIK is the most commonly used refractive surgical procedure worldwide.
Discussion The treatment effect is maximized and complications kept to a minimum if strict inclusion criteria are applied and a high technical standard maintained during the procedure.
The learning objectives of this article are that the reader should become familiar with the different techniques of refractive surgery now available for the correction of refractive errors of the human eye, should know the indications for each technique according to the guidelines of the German Commission for Refractive Surgery, and should be able to inform patients about the contraindications and possible complications of each technique.
Refractive errors. Refractive errors in the human eye Refractive errors are measured in diopters D and are classified as axially symmetrical, astigmatic, or most commonly mixed. Open in a separate window. Figure 1.
Refractive surgical techniques Two currently established surgical methods for the correction of refractive error are refractive corneal surgery and refractive lens surgery. Refractive corneal surgery An excimer "excited dimer" laser is an argon fluoride laser operating with a wavelength of nanometers. The procedures employing excimer lasers to correct refractive errors are of two types: Figure 2.
Excimer laser techniques. The femtosecond laser. Incisions Incisional techniques are used to correct astigmatism.
Figure 3. Limbal relaxation incision LRI at the edge of the cornea to correct astigmatism. Incisional techniques. Refractive lens surgery An artificial lens intraocular lens can be implanted into the eye either in addition to, or instead of, the natural lens: Phakic intraocular lenses Phakic intraocular lenses are implanted into the human eye in addition to the natural ocular lens. Figure 4. Foldable phakic intraocular lenses in situ: The implantation of phakic intraocular lenses.
Figure 5. Refractive lens exchange.
Figure 6. Figure 7. Results Refractive corneal surgery Contraindications for excimer laser techniques. Refractive lens surgery Phakic intraocular lenses have proven to be an effective, safe, reliable, and stable means of correcting higher refractive errors, especially myopia. Refractive lens surgery.
Further corrections. Complications Although modern refractive surgery is remarkably successful, every refractive surgical procedure still carries a risk of complications.
Keratectasia hardly ever occurs any more as a complication, for the following reasons: Lens surgery A recognized complication of phakic anterior chamber lenses is the loss of corneal endothelial cells because of the direct or indirect contact of the artificial lens with the corneal endothelium innermost layer of the cornea.
Complications of lens surgery. Overview Refractive errors can be corrected safely, effectively, reliably, and with only rare complications by the methods of refractive surgery 15 — 20 , e8 — e9. Question 1 Which refractive errors of the human eye are classified as lower-order aberrations?
Axially symmetric myopia and astigmatism Axially symmetric types, astigmatic types, and presbyopia Myopia and hyperopia Presbyopia and astigmatism Spherical aberrations and astigmatic refractive errors Question 2 The refractive apparatus of the eye consists of which of the following? The iris, cornea, retina, and vitreous body The cornea, anterior chamber, lens, and vitreous body The ciliary muscle, cornea, iris, and posterior chamber The chamber angle, iris, vitreous body, and retina The retina, fundus of the eye, vitreous body, and cornea Question 3 In excimer laser surgery for the correction of refractive errors, what is the difference between superficial techniques PRK, epi-LASIK, LASEK and LASIK?
Question 5 What is the most common complication of LASIK about which the patient must be informed before the procedure? Corneal erosion Posterior synechia Keratectasia Photoelectric keratitis Dry eye Question 6 Where in the eye can phakic intraocular lenses be implanted? Cornea, vitreous body, iris Cornea, iris, posterior chamber Chamber angle, iris, posterior chamber Chamber angle, iris, vitreous body Anterior chamber, vitreous body, posterior chamber Question 7 A patient with myopia of —10 diopters and presbyopia of 3 diopters would like to have a phakic intraocular lens implanted.
Question 8 Your patient has read that multifocal intraocular lenses are better than monofocal intraocular ones and would like to know why. Question 9 Which of the following is a correct statement about the difference between the use of phakic intraocular lens implantation and that of refractive lens exchange? Question 10 A patient with an astigmatism of 6. No refractive methods are available to correct her astigmatism.
References 1. Kohnen T. Mrochen M, Seiler T. Ablationsprofile in der kornealen refraktiven Laserchirurgie.
Retreating residual refractive errors after excimer surgery of the cornea: J Cataract Refract Surg. Knorz MC. Komplikationen der Excimerlaser-Chirurgie zur Behandlung von Refraktionsfehlern.
Corneal ectasia induced by laser in situ keratomileusis. Infectious and noninfectious keratitis after laser in situ keratomileusis Occurrence, management, and visual outcomes. Defining subclinical keratoconus using corneal first-surface higher-order aberrations. Am J Ophthalmol. Cataract formation after implantation of myopic phakic posterior chamber IOLs. Intraindividual comparison of higher-order aberrations after implantation of aspherical and spherical intraocular lenses as a function of pupil diameter.
Six-year follow-up of laser in situ keratomileusis for moderate and extreme myopia using a first-generation excimer laser and microkeratome. Intraokularlinsen zur Korrektur von Refraktionsfehlern. Teil II: Phake Hinterkammerlinsen und refraktiver Linsenaustausch mit Hinterkammerlinsenimplantation.
Teil I: Phake Vorderkammerlinsen. Evaluation of new phakic intraocular lenses and materials. Grundlagen, Wirkungsweise und klinische Anwendungen. Long-term results of correction of high myopia with an iris claw phakic intraocular lens. J Refract Surg. Three-year follow-up of the Artisan phakic intraocular lens for hypermetropia.
Format for reporting refractive surgical data. Seiler T, Genth U. Dtsch Arztebl. Giessler S, Duncker GI. Graefes Arch Clin Exp Ophthalmol. Classification of excimer laser profiles. Optimierung der refraktiven Hornhautchirurgie. Excimer laser photorefractive keratectomy for hyperopia: Long-term study of Artisan phakic intraocular lens implantation for the correction of moderate to high myopia: Peripheral corneal relaxing incisions after ecimer laser refractive surgery.
J Cataract refract Surg. Support Center Support Center.