101
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McDonald MB, Liu JC, Byrd TJ, Abdelmegeed M, Andrade HA, Klyce SD, Varnell R, Munnerlyn CR, Clapham TN, Kaufman HE. Central photorefractive keratectomy for myopia. Partially sighted and normally sighted eyes. Ophthalmology 1991; 98:1327-37. [PMID: 1945306 DOI: 10.1016/s0161-6420(91)32128-6] [Citation(s) in RCA: 189] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Ten partially sighted and 19 normally sighted eyes underwent excimer laser photorefractive keratectomy for the correction of myopia. Nine of the partially sighted and 17 of the normally sighted eyes had 12 months of follow-up. Epithelial healing was complete in all eyes by day 6. None of the eyes had recurrent erosions, infections, or other medical complications. An increase in corneal haze after surgery was followed by a slow trend toward clearing. Average uncorrected visual acuity in the 7 normally sighted eyes with attempted corrections of 5 diopters (D) or less was 20/40 from month 2 on; the eyes with greater than 5 D attempted corrections had an average of 20/80--at month 2, which declined to 20/200--by month 6. Best spectacle-corrected visual acuity was within +/- 1 Snellen line of preoperative values in 14 of the normally sighted eyes, improved 2 or more lines in 2 eyes, and worsened two or more lines in two eyes. Hard contact lens overcorrection restored all of the two-line loss in 1 eye and 1 line of the 3-line loss in the other. Refraction and keratometry indicated corneal flattening without induced astigmatism.
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Affiliation(s)
- M B McDonald
- LSU Eye Center, Louisiana State University Medical Center School of Medicine, New Orleans 70112
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102
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Seiler T, Wollensak J. Myopic photorefractive keratectomy with the excimer laser. One-year follow-up. Ophthalmology 1991; 98:1156-63. [PMID: 1923351 DOI: 10.1016/s0161-6420(91)32157-2] [Citation(s) in RCA: 390] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
To evaluate the efficacy, predictability, and stability of myopic photorefractive keratectomy (PRK), the authors completed a 1-year follow-up study on a consecutive series of 26 sighted eyes undergoing this procedure. The results of this follow-up are presented. In addition, side effects and complications in another 255 sighted eyes with a follow-up of 3 months to 1 year are reported to judge the safety of the procedure. Twenty-four of 26 eyes (92%) were within +/- 1.0 diopter (D) of the intended final refraction (baseline, -1.4 to -9.25 D). Fifty-eight percent of the eyes were stable within +/- 0.25 D between 6 and 12 months. One year after surgery, none of the patients lost or gained more than one line of best corrected (spectacle) visual acuity. Uncorrected visual acuity improved to 20/40 or better in 96% of the eyes and to 20/20 or better in 48% of the eyes (not including the eyes that were intentionally undercorrected). However, visual acuity with glare decreased from 20/27 preoperatively to 20/31 after 1 year. Scarring occurred in 2.8% of the treated corneas. Risk factors for scarring include noncompliance with postoperative steroid medication, high myopic corrections, and high steroid responders (3.1%). Collagen vascular and other autoimmune diseases are a contraindication for PRK.
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Affiliation(s)
- T Seiler
- Universitäts-Augenklinik im Klinikum Charlottenburg Freie Universität, Berlin, Germany
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103
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Gartry D, Kerr Muir M, Marshall J. Excimer laser treatment of corneal surface pathology: a laboratory and clinical study. Br J Ophthalmol 1991; 75:258-69. [PMID: 1817467 PMCID: PMC1042351 DOI: 10.1136/bjo.75.5.258] [Citation(s) in RCA: 105] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The argon fluoride excimer laser emits radiation in the far ultraviolet part of the electromagnetic spectrum (193 nm). Each photon has high individual energy. Exposure of materials or tissues with peak absorption around 193 nm results in removal of surface layers (photoablation) with extremely high precision and minimal damage to non-irradiated areas. This precision is confirmed in a series of experiments on cadaver eyes and the treatment of 25 eyes with anterior corneal disease (follow-up 6 to 30 months). Multiple zone excimer laser superficial keratectomy is considered the treatment of choice for rough, painful corneal surfaces. All patients in this group were pain-free postoperatively. Where good visual potential exists, ablation of a single axial zone is recommended and results in improved visual acuity and reduction of glare. A hyperopic shift was noted in this group.
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104
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McDonnell PJ, Garbus JJ, Salz JJ. Excimer Laser Myopic Photorefractive Keratectomy After Undercorrected Radial Keratotomy. J Refract Surg 1991. [DOI: 10.3928/1081-597x-19910301-08] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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105
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Ediger MN. Excimer-laser-induced fluorescence of rabbit cornea: radiometric measurement through the cornea. Lasers Surg Med Suppl 1991; 11:93-8. [PMID: 2034015 DOI: 10.1002/lsm.1900110202] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The laser-induced fluorescence spectrum of rabbit cornea irradiated at ablative intensities was measured. This system directly measured the radiant exposure of fluorescence transmitted through the cornea when the anterior surface of the cornea was irradiated by an ArF excimer laser. Evidence of changing spectral characteristics as a function of total laser dose suggests photochemical changes in the cornea may be occurring. Results are compared with previous data of laser-induced fluorescence in other models and detection schemes.
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Affiliation(s)
- M N Ediger
- Center for Devices and Radiological Health, Food and Drug Administration, Rockville, Maryland 20857
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106
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Palanker D, Ohad S, Lewis A, Simon A, Shenkar J, Penchas S, Laufer N. Technique for cellular microsurgery using the 193-nm excimer laser. Lasers Surg Med Suppl 1991; 11:580-6. [PMID: 1753851 DOI: 10.1002/lsm.1900110613] [Citation(s) in RCA: 56] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
A new cell surgery technique has been developed to produce well-defined alterations in cells and tissue without detectable heating and/or other structural damage in the surroundings. The technique involves the use of an argon fluoride excimer laser, in the deep ultraviolet (UV) region of the spectrum at 193 nm, which is guided through a glass pipette filled with a positive air pressure. To demonstrate the method, holes were drilled in the zona pellucida of mouse oocytes. The diameter of the drilled hole was determined by the pipette tip size, and its depth by an energy emitted per pulse and number of pulses. Scanning electron microscopy of the drilled mouse oocytes showed uniform, round, well-circumscribed holes with sharp edges. Oocytes that had their zona pellucida drilled with this new method fertilized in vitro and developed to the blastocyst stage in a rate similar to that of control group. These results demonstrate the nonperturbing nature of this cold laser microsurgical procedure. In addition to the extension of our results for clinical in vitro fertilization purposes, such as enhancement of fertilization and embryo biopsy, there are wide-ranging possible uses of our method in fundamental and applied investigations that require submicron accuracy in cellular alteration.
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Affiliation(s)
- D Palanker
- Hadassah Laser Center, Hebrew University of Jerusalem, Givat Ram, Israel
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107
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Gailitis RP, Ren QS, Thompson KP, Lin JT, Waring GO. Solid state ultraviolet laser (213 nm) ablation of the cornea and synthetic collagen lenticules. Lasers Surg Med 1991; 11:556-62. [PMID: 1753850 DOI: 10.1002/lsm.1900110610] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
We used a Q-switched Nd:YAG laser with non-linear optical crystals to produce the 5th (213 nm) and the 4th (266 nm) harmonic frequencies. Using these two wavelengths, we ablated fresh porcine corneas and type I collagen synthetic epikeratoplasty lenticules. For the 213-nm ablation, radiant exposure was 1.3 J/cm2. The ablation rate was 0.23 micron per pulse for the epikeratoplasty lenticules. We examined all tissues with light microscopy, transmission electron microscopy, and scanning electron microscopy. Histology for the 213-nm ablation showed a clean ablation crater with minimal collagen lamellae disruption and a damage zone less than 1 micron. In comparison, the 266 nm radiation showed more charring at the edges with a damage zone approximately 25 microns deep with disruption of the stromal lamella. Our results show that this solid state UV laser is a potential alternative to the excimer laser for cornea surgery.
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Affiliation(s)
- R P Gailitis
- Department of Ophthalmology, Emory University, Atlanta, Georgia
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108
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109
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Van Saarloos PP, Constable IJ. Bovine Corneal Stroma Ablation Rate With 193-nm Excimer Laser Radiation: Quantitative Measurement. J Refract Surg 1990. [DOI: 10.3928/1081-597x-19901101-08] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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110
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Liu JC, McDonald MB, Varnell R, Andrade HA. Myopic Excimer Laser Photorefractive Keratectomy: An Analysis of Clinical Correlations. J Refract Surg 1990. [DOI: 10.3928/1081-597x-19900901-06] [Citation(s) in RCA: 62] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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111
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112
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Hanna KD, Pouliquen YM, Savoldelli M, Fantes F, Thompson KP, Waring GO, Samson J. Corneal Wound Healing in Monkeys 18 Months After Excimer Laser Photorefractive Keratectomy. J Refract Surg 1990. [DOI: 10.3928/1081-597x-19900901-09] [Citation(s) in RCA: 69] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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113
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Seiler T, Kahle G, Kriegerowski M. Excimer Laser (193 nm) Myopic Keratomileusis in Sighted and Blind Human Eyes. J Refract Surg 1990. [DOI: 10.3928/1081-597x-19900501-04] [Citation(s) in RCA: 169] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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114
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Del Pero RA, Gigstad JE, Roberts AD, Klintworth GK, Martin CA, L'Esperance FA, Taylor DM. A refractive and histopathologic study of excimer laser keratectomy in primates. Am J Ophthalmol 1990; 109:419-29. [PMID: 2330944 DOI: 10.1016/s0002-9394(14)74608-2] [Citation(s) in RCA: 110] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Using a 193-nm excimer laser, we produced wide-area, refractive keratectomies on 18 cynomolgus monkey corneas and followed them up for up to 18 months. All corneas developed some subepithelial haze by one month. Electron microscopy disclosed epithelial thickening, absence of Bowman's layer, and subepithelial activated fibroblasts surrounded by disorganized collagen. By six months, the haze faded to a variable degree, the epithelium regained normal thickness, and the collagen was more organized. Persistent corneal haze at 12 months in some corneas correlated with electronlucent spaces in the subepithelial zone. Corneas were 90 microns thinner centrally two weeks after myopic ablation, but returned to preoperative thickness by six months. Myopic flattening and hyperopic steepening of 6 diopters were targeted, and over 7 diopters of each were achieved initially. Regression of induced curvature stabilized over several months. At 18 months, 4.4 diopters of myopic flattening and 5.2 diopters of hyperopic steepening remained.
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Affiliation(s)
- R A Del Pero
- University of Connecticut Health Center, Farmington
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115
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Pallikaris IG, Papatzanaki ME, Stathi EZ, Frenschock O, Georgiadis A. Laser in situ keratomileusis. Lasers Surg Med 1990; 10:463-8. [PMID: 2233101 DOI: 10.1002/lsm.1900100511] [Citation(s) in RCA: 345] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
A new laser refractive procedure is being developed in a rabbit model. With a modified microkeratome, central corneal flaps were created. An ArF excimer laser was used to produce 3-mm-diameter circular ablations on the central part of the exposed stromal bed. One group of animals was sacrificed immediately postoperatively, and both the dissected and ablated areas were studied using scanning electron microscopy. A second group of animals was sacrificed 4 weeks postoperatively. In this group, the subsequent healing of the corneas was studied using light microscopy. At 3 days, the wounded stromal areas showed some degree of haze. Haze was progressively reduced over 1 month, but it could be still discerned biomicroscopically. A hemicircular opacification corresponding to the flap edges was also apparent on slit-lamp examination. Microscopic observation showed that the epithelium was normal, except at the flap margins, where it was thickened. An increased number of keratocytes was observed in the interface between the flap stroma and the ablated area. The procedure might induce stable corneal changes because of the preservation of the anterior layers of the cornea.
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Affiliation(s)
- I G Pallikaris
- Department of Ophthalmology, School of Health Sciences, University of Crete, Greece
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