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Abstract
BACKGROUND We previously described a simple test which evaluates image degradation in post-excimer laser (PRK) patients under scotopic conditions. After refractive surgery, corneal haze, ablation zone decentration, ablation zone/pupillary diameter disparity, and under-correction each result in a characteristic pattern on the Night Vision Recording Chart. METHODS Using the same method, further studies evaluated night vision image degradation in 118 un-operated emmetropic, myopic, hyperopic, and astigmatic eyes and in 26 contact lens wearers. RESULTS Scotopic image degradation increases with myopic refractive error, image displacement increases with astigmatism, and contact lens wearers have more image degradation that with spectacle correction. CONCLUSION Our Night Vision Recording Chart offers a simple, reproducible method to characterize image degradation under scotopic conditions.
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Choy DS, Altman P, Trokel SL. Efficiency of disc ablation with lasers of various wavelengths. JOURNAL OF CLINICAL LASER MEDICINE & SURGERY 1995; 13:153-6. [PMID: 10150639 DOI: 10.1089/clm.1995.13.153] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
In testing the CO2 lasers in CW and pulse mode, the erbium:YAG, the Nd:YAG 1318 microns and 1064 microns, the argon, the holmium:YAG, and the excimer, we found the greatest efficiency in the CO2 CW and pulse mode, and the lowest efficiency in the argon. Data with the holmium:YAG were unreliable because of the early generation laser tested. The Nd:YAG was second only to the CO2 laser, and because the latter has no waveguide, we deemed the Nd:YAG the laser of choice for PLDD.
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Campos M, Lee PP, Trokel SL, Taylor HR, McDonnell PJ. Transconjunctival sinusotomy using the 193-nm excimer laser. Acta Ophthalmol 1994; 72:707-11. [PMID: 7747580 DOI: 10.1111/j.1755-3768.1994.tb04685.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Successful surgical management of glaucoma is limited as a consequence of undesired fibroblastic response of episcleral tissues. In 10 rabbit and three human eye bank eyes, we have performed a modified sinusotomy procedure using the 193-nm excimer laser. The technique is minimally invasive. Conjunctiva is pulled over the corneoscleral limbus, and a slit-shaped (1 x 2 mm) excimer beam ablates through conjunctiva and external sclera until penetrating the outer wall of Schlemm's canal, at which time brisk egress of fluid is noted. The conjunctiva is allowed to retract, and a conjunctival bleb is formed. A single suture is used to close the conjunctival defect. Intraocular pressure in the rabbit eye was decreased from 10.0 +/- 1.8 to 4.9 +/- 1.8 mmHg immediately after surgery (p < 0.0001). Histology revealed a partial thickness, smooth-walled ablation consistent with a sinusotomy. This procedure is minimally invasive and may be useful for management of glaucoma, particularly when a substantial component of the impediment to aqueous outflow is external to the trabecular meshwork.
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Gibralter R, Trokel SL. Correction of irregular astigmatism with the excimer laser. Ophthalmology 1994; 101:1310-4; discussion 1314-5. [PMID: 8035996 DOI: 10.1016/s0161-6420(94)31174-2] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
BACKGROUND Correction of irregular astigmatism has not been possible using available keratorefractive technology. METHODS The authors used a topographic map as a guide and created a custom excimer ablation program, designed to create a more regular surface. The program consisted of a combination of phototherapeutic and photorefractive ablation patterns. The amount of tissue to be removed was calculated on the basis of the diameter and steepness of the irregular areas of the corneal surface. RESULTS A more regular surface, as evidenced by topographic analysis, reduced astigmatism, and improved uncorrected visual acuity, was produced. CONCLUSION Using the corneal topographical map as a guide, excimer laser ablation can be used to create a more regular optical surface with improved visual function.
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Florakis GJ, Jewelewicz DA, Michelsen HE, Trokel SL. Evaluation of night vision disturbances. JOURNAL OF REFRACTIVE AND CORNEAL SURGERY 1994; 10:333-8. [PMID: 7522090] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
BACKGROUND Evaluation of night vision disturbances has relied on subjective responses. We designed a test to more objectively measure night vision disturbances. METHODS The test consisted of projecting a small circle onto a visual acuity screen. The patient is asked to draw exactly what he sees on an Amsler grid. We evaluated 118 eyes in photopic and scotopic conditions and under different conditions of refractive correction. RESULTS Image degradation increased in scotopic conditions for myopes (p = .0001), hyperopes (p = .005), and emmetropes (p = .01). Myopic refractive error correlated with size of glare response (p = .001). Astigmatism correlated with decentration of glare response (p = .0001). Decentration increased in scotopic compared to photopic conditions (p = .002). CONCLUSION Our test offers a simple, convenient way to evaluate night vision disturbances and may offer a means of assessing night vision disturbances in patients considering refractive surgery.
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Florakis GJ, Jewelewicz DA, Michelsen HE, Trokel SL. Evaluation of Night Vision Disturbances. J Refract Surg 1994. [DOI: 10.3928/1081-597x-19940501-06] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Abstract
PURPOSE The authors developed a system for producing topographic pachymetric maps of the corneal epithelium and anterior scar tissue. METHOD The system uses high-frequency ultrasound scanning enhanced by digital signal processing. Ultrasonic echo data from consecutive parallel B-scans of the cornea spaced at 250-microns intervals are digitized and stored. Using the I-scan (obtained by computing the analytic signal magnitude of the deconvolved ultrasound signal), layer thickness measurements are made with a precision of 2 microns (standard deviation) at 120-microns intervals along each scan plane. The data are stored as an array, z(x,y), mapping thickness, z, onto horizontal and vertical (x,y) spatial coordinates. Pachymetric maps are then constructed by plotting local thickness, represented by a color scale, against measurement point position. RESULTS Examples of a normal cornea, a contact lens-wearing cornea, Reis-Bückler dystrophy, and postphotorefractive keratectomy are presented. Areas with significant subepithelial scarring and general epithelial thickening in a subject with Reis-Bückler dystrophy are mapped. Unevenness in the epithelial thickness profile of the cornea in a subject after photorefractive keratectomy is shown, relative to the fellow (untreated) cornea. CONCLUSION This technique provides the corneal surgeon with a new tool for the topographic evaluation of the thickness of anterior corneal layers in normal and pathologic corneas with high precision. In addition, the technique is not limited to optically transparent tissue.
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Krueger RR, Wang XW, Rudisill M, Trokel SL, McDonnell PJ. Diffractive smoothing of excimer laser ablation using a defocused beam. JOURNAL OF REFRACTIVE AND CORNEAL SURGERY 1994; 10:20-6. [PMID: 7517775] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
OBJECTIVE To determine if excimer laser myopic ablation with a defocused laser image produces a smoother ablation profile than does focused laser light. METHODS An ArF excimer laser was used to ablate a 5.00-diopter myopic correction in test blocks using both a contracting and expanding iris aperture. Defocused ablation was performed using a contracting iris aperture by translating the target away from the laser source. A confocal laser scanning microscope was used to analyze the surface smoothness at 55x and 275x magnifications. RESULTS The confocal laser scanning micrographs revealed a series of sharply demarcated concentric ridges in the focused ablation, and less prominent, slightly wavy lines in the defocused ablation performed with a contracting aperture. The focused ablation with an expanding aperture also created concentric ridges toward the periphery, but with slightly smoother edges.
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Krueger RR, Wang XW, Rudisill M, Trokel SL, McDonnell PJ. Diffractive Smoothing of Excimer Laser Ablation Using a Defocused Beam. J Refract Surg 1994. [DOI: 10.3928/1081-597x-19940101-05] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Campos M, Trokel SL, McDonnell PJ. Surface morphology following photorefractive keratectomy. OPHTHALMIC SURGERY 1993; 24:822-825. [PMID: 8115096] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
To examine the effects of surface dehydration on corneal surface morphology before and after photorefractive keratectomy, corneas of fresh porcine eyes were deepithelialized and then immediately fixed or treated according to one of six protocols (four eyes per protocol): dehydrated under the illumination of an operating microscope; dehydrated and then rehydrated with topically applied balanced salt solution; photorefractive keratectomy; photorefractive keratectomy followed by surface dehydration; or photorefractive keratectomy followed by dehydration and subsequent rehydration. Surface smoothness (S) was measured with an image analysis system. The surfaces of the unablated corneas were smooth (S = 0.992 +/- 0.002), and dehydration did not significantly (P = .7) influence the morphology. After ablation, dehydration resulted in apparent fragmentation of the superficial lamellae, with consequent roughening of the surface (P = .0001). Rehydration was only partially successful in reducing surface irregularity. We conclude that corneal dehydration during and following photorefractive keratectomy roughens the corneal surface and should be carefully avoided.
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Campos M, Trokel SL, McDonnell PJ. Surface Morphology Following Photorefractive Keratectomy. Ophthalmic Surg Lasers Imaging Retina 1993. [DOI: 10.3928/1542-8877-19931201-04] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Campos M, Wang XW, Hertzog L, Lee M, Clapham T, Trokel SL, McDonnell PJ. Ablation rates and surface ultrastructure of 193 nm excimer laser keratectomies. Invest Ophthalmol Vis Sci 1993; 34:2493-500. [PMID: 8325755] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
PURPOSE To determine whether photorefractive keratectomy can be performed at lower energies than are currently employed in clinical trials. METHODS Fresh pig corneas were ablated using a clinical excimer laser to study the effects of various energy densities (100-200 mJ/cm2) and beam diameters on ablation rates and on the surface ultrastructure of the ablated cornea. RESULTS A 20-mJ increase in energy density was associated with a 0.03 micron per pulse increase in the ablation rate. A nearly linear increase in the pseudomembrane thickness occurred with increasing energy densities (r2 = 0.83) or decreasing ablation area diameter (r2 = 0.86). CONCLUSIONS Our findings suggest that fluences less than those currently used in clinical trials (160-180 mJ) are capable of ablating tissue while producing thinner electron-dense pseudomembranes on the corneal surface. The relationship between pseudomembrane thickness and clinical factors such as reepithelialization and postoperative haze remains to be determined. Operating at lower fluences does have the advantages of allowing larger diameter ablations, reducing possible shockwave damage, and reducing the maintenance requirements for the laser.
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Reinstein DZ, Silverman RH, Trokel SL, Allemann N, Coleman DJ. High-frequency ultrasound digital signal processing for biometry of the cornea in planning phototherapeutic keratectomy. ARCHIVES OF OPHTHALMOLOGY (CHICAGO, ILL. : 1960) 1993; 111:430-1. [PMID: 8470966 DOI: 10.1001/archopht.1993.01090040020013] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
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Kay SL, Oz MC, Haber M, Blitzer A, Treat MR, Trokel SL. Soft tissue effects of the THC:YAG laser on canine vocal cords. Otolaryngol Head Neck Surg 1992; 107:438-43. [PMID: 1408232 DOI: 10.1177/019459989210700317] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Recently, a laser based on a thulium-holmium-chromium (THC) doped Yttrium-aluminum-garnet (YAG) rod has been developed that produces light of 2.15 microns wavelength and can be transmitted through a low OH- silica fiberoptic cable. This wavelength falls on one of the peaks of the energy absorption spectrum of water. Thus, the THC:YAG laser eliminates the disadvantage of a cumbersome delivery system found in the CO2 laser while still providing precise cutting and minimal tissue injury inherent in lasers emitting light absorbed by water. We evaluated the soft tissue effects of this laser on canine vocal cords. Ablative lesions were produced by the THC:YAG laser and histologically examined on postoperative days 1, 7, and 28. Results indicate that the depth of tissue penetration is easily controlled and the healing response to tissue injury is comparable to that of the CO2 laser. The THC:YAG laser should prove to be a superior laser for use in otorhinolaryngology, especially when adapted to a flexible endoscope.
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Englanoff JS, Kolahdouz-Isfahani AH, Moreira H, Cheung DT, Nimni ME, Trokel SL, McDonnell PJ. In situ collagen gel mold as an aid in excimer laser superficial keratectomy. Ophthalmology 1992; 99:1201-8. [PMID: 1513572 DOI: 10.1016/s0161-6420(92)31822-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
PURPOSE The aim of this study is to evaluate the potential use of bovine type I collagen as an adjuvant to excimer laser keratectomy. METHOD A suspension of collagen with the capability to polymerize into a gel was applied to the anterior corneal surface of freshly enucleated porcine eyes, using 35.0 diopter (D), 45.5 D, or 52.0 D contact lenses as molds. Keratometry, photokeratoscopy, slit-lamp photography, scanning electron microscopy, and light microscopy were performed on the new surfaces. Furthermore, an irregular corneal surface was created and a suspension of collagen was applied to mask protruding irregularities, therefore creating a smooth surface that was subjected to excimer laser keratectomy. Ablation rates for both collagen and cornea were measured. RESULTS Collagen suspension placed on a cornea and molded with contact lenses created a smooth-surfaced gel that conformed to the shape of the contact lens and adhered to the anterior cornea; it was optically smooth and regular as shown by photokeratoscopy, keratometry, and scanning electron microscopy. The corneal curvature was altered in accordance with the base curvature of the contact lens used. Results of keratometry showed resolution of pre-existing astigmatism without induction of new astigmatism. The ablation rate of the gel was not measurably different than that of cornea; hence, when applied to an irregular corneal surface, a smooth surface was created after excimer laser ablation. CONCLUSION This study supports the potential value of collagen gel as an adjuvant to excimer laser keratectomy for removal of corneal irregularities as well as for correction of myopia or hyperopia with or without astigmatism.
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Abstract
Placement of the surgical zone is critical in refractive procedures that alter a portion of the corneal curve. An improperly centered optical zone may produce glare, decrease best corrected visual acuity, and decrease contrast sensitivity. For proper placement, the new surface should be centered around the line of sight, which is the principal ray from the object of regard that passes through the image of the patient's pupil as projected on the cornea. This point is not necessarily at the geometric center of the cornea and is found by locating the center of the pupil while the patient is maintaining fixation coaxially with the surgeon. However, the pupil does not dilate concentrically and its geometric center moves as the pupil diameter changes. We have found a shift up to 0.7 mm in the geometric center of the pupil as it dilates. Therefore, centration of an ablated or a radial keratotomy zone is most efficiently done when the diameter of the modified corneal optical zone is centered around the line of sight and is superimposed upon the entrance pupil. This will minimize extension of the edge of the large pupil beyond the ablated zone and reduce unwanted secondary optical effects from degrading vision.
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Krueger RR, Sliney DH, Trokel SL. Photokeratitis From Subablative 193-Nanometer Excimer Laser Radiation. J Refract Surg 1992. [DOI: 10.3928/1081-597x-19920701-06] [Citation(s) in RCA: 19] [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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Krueger RR, Sliney DH, Trokel SL. Photokeratitis from subablative 193-nanometer excimer laser radiation. REFRACTIVE & CORNEAL SURGERY 1992; 8:274-9. [PMID: 1390406] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
BACKGROUND Photokeratitis is a side effect of UV light exposure whereby the corneal epithelium is photochemically injured in a time delayed fashion. UV light exposure in the far ultraviolet wavelength range has not previously been observed. This study addresses the concern of photokeratitis from subablative 193-nanometer excimer laser light. METHODS Dutch belted rabbit corneas were irradiated with subablative 193-nanometer excimer laser light over a wide range of total energy exposures, and examined by slit lamp biomicroscope for signs of photokeratitis. Photokeratitis was identified by epithelial haze and stippling, and rose bengal and fluorescein staining at varied time intervals between 1/2 to 26 hours post exposure. RESULTS At threshold energy exposures of 1.0 to 1.5 J/cm2, an immediate superficial epithelial haze was seen which disappeared within several hours. At higher energy exposures of 10 J/cm2, a delayed photokeratitis with deep rose bengal and even fluorescein staining was seen. This latter delayed photokeratitis resembles that of longer UV wavelengths and is due to excimer laser fluorescence, whereas the former is a direct response of the 193-nanometer light. The percentage of excimer laser light undergoing fluorescence is calculated as less than 1%. CONCLUSIONS The potential side effects and hazards of scattered 193-nanometer radiation during excimer laser surgery are extremely limited because of the shorter penetration depth of direct excimer radiation and the minimal fluorescent emission of longer UV wavelengths for energy exposures within the realm of clinical use.
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Worgul BV, David J, Odrich S, Merriam GR, Medvedovsky C, Merriam JC, Trokel SL, Geard CR. Evidence of genotoxic damage in human cataractous lenses. Mutagenesis 1991; 6:495-9. [PMID: 1800897 DOI: 10.1093/mutage/6.6.495] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Lens epithelial fragments (tags) recovered from individuals during routine cataract extraction have been assessed for cellular changes reflective of genotoxic damage. A high percentage of tags exhibited a population of micronucleated and polyploid cells. The presence and number of micronuclei (MN) in the epithelia of cataract patients appears to be independent of age and sex. However, a large number of MN in the epithelial cells of some individuals strongly suggests a history of compromised genomic integrity. While the study was not designed to define the role of DNA damage in the development of cataracts or to monitor human populations at risk of exposure to exogenous mutagens/cataractogens, the potential of the methodology to address each is demonstrated.
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Choy DS, Altman PA, Case RB, Trokel SL. Laser radiation at various wavelengths for decompression of intervertebral disk. Experimental observations on human autopsy specimens. Clin Orthop Relat Res 1991:245-50. [PMID: 1904334] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The interaction of laser radiation with the nucleus pulposus from autopsy specimens of human intervertebral disks was evaluated at different wavelengths (193 nm, 488 nm & 514 nm, 1064 nm, 1318 nm, 2150 nm, 2940 nm, and 10600 nm). A significant correlation of linear least squares fit of the mass ablated as a function of incident energy was found for all lasers used except the Excimer at 193 nm. The 2940-nm Erbium:YAG laser was most efficient in terms of mass of disk ablated per joule in the limited lower range where this wavelength was observed. At higher energy levels, the CO2 laser in the pulsed mode was most efficient. However, the Nd:YAG 1064-nm and 1318-nm lasers are currently best suited for percutaneous laser disk decompression because of the availability of usable waveguides. Carbonization of tissue with the more penetrating Nd:YAG 1064-nm laser increases the efficiency of tissue ablation and makes it comparable to the Nd:YAG 1318-nm laser.
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Sliney DH, Krueger RR, Trokel SL, Rappaport KD. Photokeratitis from 193 nm argon-fluoride laser radiation. Photochem Photobiol 1991; 53:739-44. [PMID: 1886933 DOI: 10.1111/j.1751-1097.1991.tb09886.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The threshold for photokeratitis at 193 nm was obtained for the rabbit cornea using an ArF excimer laser. Because ablation occurs at a level below that for photokeratitis, it was necessary to expose the cornea to a lengthy series of low-energy exposures. It is concluded that the 193 nm photons have such a shallow penetration depth, being limited to the outermost epithelial cells, that classical photokeratitis occurs from the fluorescence emitted at the corneal epithelial absorption site. An intact tear film may help to protect the cornea from low-level, scattered 193 nm laser radiation.
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Bass LS, Oz MC, Trokel SL, Treat MR. Alternative lasers for endoscopic surgery: comparison of pulsed thulium-holmium-chromium:YAG with continuous-wave neodymium:YAG laser for ablation of colonic mucosa. Lasers Surg Med Suppl 1991; 11:545-9. [PMID: 1753849 DOI: 10.1002/lsm.1900110608] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Precise and controllable tissue vaporization is essential for minimizing risk in removal of sessile polyps from the lumen of thin walled gastrointestinal organs such as the colon. We compared the ablative efficiency on canine colonic mucosa of the THC:YAG laser with the clinically employed cw Nd:YAG laser. Fresh canine colon was treated with a progressive dose schedule using each laser at several energy/power densities. Ablation depth was measured on fresh tissue and thermal (non-ablation or coagulative) damage examined histologically. The THC:YAG ablation rates were 13.7 +/- 0.8 and 10.2 +/- 0.4 microns/J at 55 and 85 J/cm2, respectively. The Nd:YAG laser generated 3.7 +/- 0.3, 2.8 +/- 0.1, and 3.6 +/- 0.2 microns/J at 4,460, 5,095, and 5,730 W/cm2, respectively. There was a significant (P less than 0.001) difference among the THC:YAG ablation rates and between the THC:YAG and Nd:YAG ablation rates (ANOVA). The THC:YAG laser craters had significantly less collateral thermal damage than Nd:YAG. The pulsed THC:YAG laser should have an important clinical role since its use could reduce the risk of perforation in endoscopic laser procedures such as the removal of sessile polyps.
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Oz MC, Lemole GM, Treat MR, Trokel SL, Andrew JE, Barr ML, Marboe CS, Nowygrod R. Effects of a 2.15-micron laser on human atherosclerotic xenografts in vivo. Angiology 1990; 41:772-6. [PMID: 2221477] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The thulium-holmium-chromium:yttrium-aluminum-garnet (THC:YAG) laser has a tissue effect similar to that of the CO2 laser, with the advantage of transmissibility through flexible fibers. The authors used a human-rabbit xenograft model to evaluate the thrombotic and healing responses of atherosclerotic vessels subjected to laser energy. Occluded atherosclerotic human coronary artery segments were recanalized in vitro by use of the THC:YAG laser. Destruction of plaque by the laser was achieved with minimal collateral thermal damage. These vascular segments were then transplanted into the rabbit abdominal aorta. The authors observed that the luminal surface of the lased vessels was more thrombogenic than that of the nonlased control vessels. However, occlusion of the lased vessels did not occur. Repair of laser-treated tissue progressed until a mature, nonthrombogenic fibrin-platelet aggregate was adherent to the luminal wall. Overall, the lased vessels behaved in a fashion similar to the nonlased control vessels. On the basis of these results, the authors believe that the THC:YAG laser may have use in human angioplasty.
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Trokel SL. Development of the excimer laser in ophthalmology: a personal perspective. REFRACTIVE & CORNEAL SURGERY 1990; 6:357-62. [PMID: 2257262] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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