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At least 955 records · Page 53Linked to original sources
PubMed2000

Excimer laser photorefractive keratectomy and laser in situ keratomileusis for myopia and astigmatism.

The efficacy, predictability, safety, and short-term stability of excimer laser photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) for treatment of myopia and astigmatism were determined. The preoperative myopia ranged from -1.50 to -15.75 D and the astigmatism was less than 4.0 D. Of the 147 eyes, 73 and 74 underwent PRK and LASIK, respectively. Mean preoperative spherical equivalent refraction (SE) was -3.72 +/- 1.69 D in the PRK group and -7.66 +/- 2.30 D in the LASIK group. Mean postoperative SE at the last examination (3 to 6 months) was -0.13 +/- 0.82 D and -0.38 +/- 1.19 D in the PRK and LASIK groups, respectively. Eighty six percent in the PRK group and 77 per cent in the LASIK group achieved a SE within +/- 1.0 D and the refractions were stable between 1 month and 3-6 months. Uncorrected visual acuity of 20/40 or better was noted in 91 per cent in the PRK group and 97 per cent in the LASIK group. No eyes lost one or more lines of best spectacle-corrected visual acuity in both groups. PRK and LASIK appear to be effective, safe, predictable, and short-term stable in treating myopia and astigmatism. Longer follow-up studies will help evaluate the long-term stability of the procedure and possibility of later complications.

Adult↗
PubMed2004

[Comparison of results of photorefractive keratectomy and laser in situ keratomileusis in the treatment of hyperopia using a flying spot eximer laser].

PURPOSE: To evaluate the results of photorefractive keratectomy (PRK) and Laser in situ keratomieusis (LASIK) in eyes treated with hyperopia. PATIENTS AND METHODS: group 1 consisted of PRK-operated eyes, group 2 consisted of LASIK-operated eyes. In each group 20 eyes of 20 patients were listed. The average age in Group 1 was 33.4 +/- 8.4 year, while in group 2 it was 34.2 +/- 7.9 year. Refractive treatments were carried out with the Asclepion Meditec MEL 70 G-Scan flying spot excimer laser, LASIK flaps were created by the Moria CB manual microkeratome. RESULTS: In group 1, pre-operative refraction was +4.2 +/- 1.1 D (SE = spherical equivalent), in group 2 it was +4.8 +/- 1.21 D. Six months following surgery refraction was +0.35 +/- 0.12 D (SE) in group 1, while +0.38 +/- 0.14 D (SE) in group 2. The uncorrected visual acuity was 0.92 +/- 0.04 in group 1 and 0.91 +/- 0.01 in group 2.85% of eyes in group 1 and 95% of eyes in group 2 had a 1.0 uncorrected visual acuity. In group 1, 95% of the eyes were within +/- 1.0 D of targeted refraction, while in group 2, 100% achieved this. Best spectacle corrected visual acuity (BSCVA) did not change in 90% of group 1, while in 5% it increased by 1 and in the remaining 5% decreased by 1 Snellen line. In group 2. BSCVA remained unchanged in 85% of eyes, while in 10% it increased and in 5% decreased by 1 Snellen line. In group 1, glare was reported in 4 eyes, while in group 2.5 eyes reported postoperative glare, mainly during night driving. CONCLUSION: Effectivity, predictability and safety was good in both treatment groups. Results of hyperopic eyes below +6.0 D of preoperative refraction were not dependent on the type of operation (PRK or LASIK).

Adult↗
PubMed2005

[Recovery of corneal sensitivity after laser in situ keratomileusis and laser-assisted subepithelial keratectomy].

OBJECTIVE: To compare the recovery of corneal sensitivity after laser in situ keratomileusis (LASIK) and laser-assisted subepithelial keratectomy (LASEK). METHODS: Central corneal sensitivity (CCS) was measured with a Cochet-Bonnet esthesiometer in 59 patients before and 2 weeks, 1, 3 and 6 months after myopic correction by LASIK or LASEK. Among them, 50 patients were treated with LASEK and 9 patients were treated with LASIK. RESULTS: CCS were reduced in the early period time after LASEK and LASIK, but more reduction was seen after LASIK. At every time points, the CCS after LASEK was better than that after LASIK (at 2 weeks, 1 and 3 months P < 0.01, at 6 months P = 0.031). In myopic eyes with less than 6.00 diopters (D), the CCS recovered at 3 months after LASEK (P > 0.05), but it didn't recover at 6 months after LASIK (P = 0.023). In myopic eye with more than 6.00 D, the recovery of CCS was seen at 6 months after LASEK (P > 0.05). Correlations between CCS and ablation depth were found at 3 and 6 months after LASEK (r = 0.419, 0.433, 0.413; P < 0.05), but no correlation was found after LASIK (P > 0.05). CONCLUSION: Recovery of corneal sensitivity is faster after LASEK than after LASIK. Ablation depth is related to the recovery of corneal sensitivity after LASEK.

Adolescent↗
PubMed2006

[Stromal cells change after epipolis laser in situ keratomileusis and laser-assisted subepithelial keratectomy in rabbits].

OBJECTIVE: To compare the effects of epipolis laser in situ keratomileusis (Epi-LASIK) and laser-assisted subepithelial keratectomy (LASEK) on the corneal stromal cells, and to evaluate their effects on corneal haze histopathologically. METHODS: Forty-eight New Zealand white rabbits (96 eyes) were randomly treated with Epi-LASIK in one eye and LASEK in the other, and 2 rabbits (4 eyes) without any treatment were used as control. Cornea stromal cell apoptosis was evaluated by terminal deoxyribonucleotidyl transferase-mediated deoxynuridine triphosphate nick end labeling (TUNEL) assay. Stromal cells proliferation and myofibroblasts generation were evaluated by immunocytochemical analyses the expression of Ki-67 and alpha-smooth muscle actin (alpha-SMA) respectively. Myofibroblast generation was further testified by Western blot analysis of alpha-SMA. Both number of TUNEL, Ki-67 and alpha-SMA positive cells and expression of alpha-SMA were semi quantitatively analyzed to explore their effects on corneal haze. RESULTS: Many TUNEL-positive cells appeared in the central anterior stromal in early stages after both LASEK and Epi-LASIK, and the number of TUNEL-positive cells reached a peak 24 hours after either LASEK or Epi-LASIK. There were more TUNEL positive cells found in LASEK group than that in Epi-LASIK group in 1 week postoperatively (t = 3.63, 7.80, 4.34, 2.95, all P < 0.01). There were a lot of Ki-67-positive cells in anterior corneal stroma after both LASEK and Epi-LASIK, but the peak appeared at 72 hours after the treatments. The significant difference was also found in the number of Ki-67-positive cell between the two treatments in 1 week postoperatively (t = 3.81, 5.85, 5.09, 5.59, all P < 0.01). alpha-SMA-positive cells started to appear apparently at 1 week after both LASEK and Epi-LASIK, and both the peaks appeared at 1 month after the treatments, and there were still a lot of alpha-SMA-positive cells in corneal stroma at 3 months after LASEK. There were more alpha-SMA-positive cells found after 1 week in LASEK group than that in Epi-LASIK group (t = 2.97, 7.19, 6.73, all P < 0.01). CONCLUSION: There are less stromal cell apoptosis, proliferation and myofibroblast generation in Epi-LASIK than that in LASEK. Therefore, comparing with LASEK, Epi-LASIK induces less corneal haze response in correcting myopia.

Actins↗
PubMed1979

[Hemostatic effects of the argon laser on the gastric wall in the dog. I. Preliminary study: effects of the laser on the normal gastric wall].

The authors describe the pathological lesions caused by argon laser emitted rays on the healthy gastric mucosa in 22 dogs. They compare 126 photocoagulated areas while varying the intensity and the exposure time of the laser ray in order to determine the ideal constants of an efficient photocoagulation, devoid of risk and with rapid healing of the lesions.

Animals↗
PubMed1979

[Results of helium-neon laser radiation action on the hematopoietic system experimentally and in the laser therapy of surgical diseases].

The investigation of effects of the red light of the helium-neon laser on hemopoiesis of experimental animals has provided data on the activation of erythropoiesis and the presence of the leucocyte redistribution reaction in the peripheral blood. No pathological changes in the morphological composition of the peripheral blood were detected in patients with a deforming arthrosis and patients with gastric ulcer in the process of laser therapy. Favourable changes were noted.

Animals↗
PubMed1995

One-year evaluation of excimer laser photorefractive keratectomy for myopia and myopic astigmatism. Melbourne Excimer Laser Group.

OBJECTIVE: To evaluate prospectively the efficacy and safety of excimer laser photorefractive keratectomy in the treatment of myopia and myopic astigmatism. METHODS: Up to 15 diopters (D) of myopia with or without astigmatism of less than 6 D was treated with an excimer laser (VISX Twenty/Twenty). One hundred fifty procedures have been followed up for more than 12 months. RESULTS: Postoperative refractions were generally stable after 3 months without significant early overcorrection. Of those eyes treated with spherical equivalents of 5 D or less, 96% were within 1 D of the targeted refraction after photorefractive keratectomy and 88% had uncorrected visual acuities of 20/40 or better. At 12 months, 77% of all 150 eyes treated achieved an uncorrected visual acuity of 20/40 or better and 81% were within 1 D of the intended correction. Nine eyes (6%) lost 2 or more lines of best corrected visual acuity and 14 (9%) gained 2 or more lines. Adverse reactions were reported in 12 patients (8%) during the postoperative period. CONCLUSIONS: Photorefractive keratectomy is capable of correcting low and moderate myopic errors with a relatively high degree of accuracy and safety. The predictability and stability of the postoperative refraction during the first 12 months seem to be good.

Adult↗
PubMed1996

Overcorrection after excimer laser treatment of myopia and myopic astigmatism. Melbourne Excimer Laser Group.

OBJECTIVE: To study the incidence and associations of overcorrection after excimer laser treatment of myopia and myopic astigmatism. METHODS: The study cohort consisted of 645 patients who had photorefractive or photoastigmatic refractive keratectomy done by an excimer laser during a 2-year period. Patients were assessed 1,3,6, and 12 months postoperatively. The variables evaluated were visual acuity, refraction, keratometry, and corneal clarity. RESULTS: At 1 month, overcorrection of more than +1 diopter spherical equivalent (SEQ) was seen in 22% of the eyes. This progressively regressed so that only 8.6% of the 140 eyes that were overcorrected at 1 month were overcorrected at 1 year. Overall, 2.2% of eyes were overcorrected at 1 year. The magnitude of attempted correction and use of topical nonsteroidal anti-inflammatory drugs disclosed a notable association with occurrence of overcorrection at 1, 3, and 6 months. The use of bandage contact lenses also was associated with overcorrection at 1 and 3 months. After controlling for myopia and use of contact lenses, the odds of overcorrection for use of topical nonsteroidal anti-inflammatory drugs at 1,3, and 6 months were 2.21 (95% confidence limits [CL]=1.49, 3.44), 1.69 (95% CL=0.88, 3.24), and 2.01 (95% CL=0.88, 4.56), respectively. The odds of overcorrection with bandage contact lenses were 1.79 (95% CL=1.05, 3.05) at 1 month and 2.42 (95% CL=1.23, 4.75) at the end of 3 months. No associations were seen between overcorrection and age, gender, surgical technique, or simultaneous astigmatic corrections. CONCLUSIONS: Overcorrection is common during the early postlaser treatment period and is associated with degree of myopia, use of nonsteroidal anti-inflammatory drugs, and bandage contact lens wear.

Adult↗
PubMed1999

Comparative mass spectrometric analyses of Photofrin oligomers by fast atom bombardment mass spectrometry, UV and IR matrix-assisted laser desorption/ionization mass spectrometry, electrospray ionization mass spectrometry and laser desorption/jet-cooling photoionization mass spectrometry.

Photofrin (porfimer sodium) is a porphyrin derivative used in the treatment of a variety of cancers by photodynamic therapy. This oligomer complex and a variety of porphyrin monomers, dimers and trimers were analyzed with five different mass spectral ionization techniques: fast atom bombardment, UV and IR matrix-assisted laser desorption/ionization, electrospray ionization, and laser desorption/jet-cooling photoionization. All five approaches resulted in very similar oligomer distributions with an average oligomer length of 2.7 +/- 0.1 porphyrin units. In addition to the Photofrin analysis, this study provides a side-by-side comparison of the spectra for the five different mass spectrometric techniques.

Dihematoporphyrin Ether↗
PubMed2003

Indirect laser-induced fluorescence detection for capillary electrophoresis using a frequency-doubled diode laser.

A blue (452 nm) frequency-doubled diode laser with a quasi-cw optical output power of 10 microW is used for indirect laser-induced fluorescence detection in combination with the capillary electrophoretic separation of inorganic anions. As fluorescing probe ion the anion of 8-hydroxypyrene-1,3,6-trisulfonic acid (HPTS) was selected having an absorption maximum of 454 nm in alkaline medium. Employing a capillary coated with linear acrylamide, baseline separation of eight inorganic anions was possible within 5 min. With a separation buffer containing 50 micromol.L(-1) HPTS and 10 mmol.L(-1) lysine the limits of detection for sulfate, nitrite, nitrate, azide, thiocyanate, and chlorate were between 0.9 and 4.7 micromol.L(-1). Separation of chloride and sulfate was achieved by adding 0.25 mmol.L(-1) calcium hydroxide to the separation buffer. Inorganic anions in several mineral and tap water samples have been determined with the technique developed and results are compared to data obtained by ion chromatography in combination with conductivity detection after conductivity suppression.

Anions↗
PubMed2001

Vascular procedures that thermo-coagulate collagen reduce local platelet deposition and thrombus formation: laser and laser-thermal versus balloon angioplasty.

BACKGROUND AND OBJECTIVE: Exposure of the arterial wall matrix to blood leads to platelet deposition resulting in thrombosis. Because heat alters tissue matrix we proposed that heating reduces platelet deposition. STUDY DESIGN/MATERIALS AND METHODS: Sixty arterial homografts (15 dogs) were mounted in an arterio-venous "shunt." Interventions included balloon angioplasty (BA), direct laser (LA), laser-thermal (LTA), and combined LTABA. 111Indium-labeled platelets were circulated, radio activity measured, and homografts processed for histology. RESULTS: Radioactivity count (mean+/- SE) at BA sites (13,853+/-3,192 cpm/cm(2)) was greater than LA (7,038+/-981), LTA (5,294 +/-1,145), LTABA (6,176+/-1,571), and control (1,826+/-339), P<0.05. Electron microscopy showed fewer platelets at LA, LTA, and control than BA sites. BA spread the collagen on the arterial lumen while heat gelled collagen and confined it to the arterial media. CONCLUSIONS: Heating the artery and gelling collagen during LA, LTA, or LTABA significantly reduced thrombogenicity.

Angioplasty, Balloon↗
PubMed2001

Excimer laser (308 nm) based transmyocardial laser revascularization: effects of the lasing parameters on myocardial histology.

BACKGROUND AND OBJECTIVE: The effect of the excimer laser (308 nm) parameters on transmyocardial revascularization (TMR) channels is not well defined. This study investigates the influence of the pulse repetition rate, the size of the delivery catheter and its advancement speed on the morphology of TMR channels in vivo. STUDY DESIGN/MATERIALS AND METHODS: Myocardial ablation was performed in a porcine model (N = 27) using multifiber catheters of 1.0 and 1.4 mm in diameter. The catheters were advanced into the myocardium at different speeds (1.27 and 2.54 mm/sec) while ablating at various repetition rates (10-80 Hz). The radiant exposure was kept at 35 mJ/mm(2) throughout the experiments. The channel histology was quantified by digital microscopy. RESULTS: The channel cross-sectional area and the extent of the thermal damage decrease as the catheter advancement speed exceeds the ablation speed and vice versa. Within the parameters tested, advancement speed of about 1.3 mm/sec and pulse repetition rates of 40 Hz produce channels of size comparable to the catheter's diameter with moderate thermomechanical damage. CONCLUSIONS: The repetition rate, catheter size, and catheter advancement speed are closely intertwined and crucial to the histological outcome of excimer laser based TMR.

Animals↗
PubMed2001

Angiogenesis three months after clinical transmyocardial laser revascularization using an excimer laser.

BACKGROUND AND OBJECTIVE: We present for the first time histologic findings 3 months after clinical transmyocardial laser revascularization using a XeCl excimer laser. STUDY DESIGN/MATERIALS AND METHODS: Histology was performed on a patient who died from a noncardiac cause 3 months post-excimer TMLR. RESULTS: In the treated myocardium, no patent channels were found but scars were seen with a linear distribution and in continuity with circumscribed small fibrotic endocardial and epicardial scars. The scars were highly vascularized by new vessels, ranging from small capillaries to large thin walled, and sometimes branching ectatic vessels. Sprouting of vessels into the adjacent myocardium was also observed. CONCLUSION: These results suggest that angiogenesis might play a role in the clinical improvement after TMLR.

Aged↗
PubMed1988

Nd-YAG laser energy distribution in an artificial obstruction: influence of lasing parameters in a model of laser angioplasty.

A Nd-YAG laser (1064 nm) coupled to a silica fiber (0.6 mm core diameter) was used to create defects in a model of arterial vascular obstruction. We employed transparent agar doped with black ink as atheromatous material and studied the size and shape of defects created by various lasing parameter settings. By adding calcium sulphate to the agar its scattering properties were enhanced. The created defects correspond to a temperature boundary. The optical properties of the agar greatly influenced the size and shape of the created defects. In the agar with enhanced scattering properties, the created defects showed an unfavourable penetration width-depth ratio. Maximum width of penetration always exceeded the fiber diameter. This may contribute to an increased risk of vessel wall perforation in small vessels and, if the fiber is positioned close to the vessel wall, even when a coaxial position is maintained. With increasing cumulative energy, both maximum depth and width of penetration leveled off in both agars. The results suggest that agar can be used to obtain empirically the lasing parameters that will minimize the risk of vessel wall perforation by an axially positioned fiber. The agar model needs further study to determine its limitations, but agar seems to be a useful substitute for atheroma in the study of laser catheter angioplasty.

Agar↗
PubMed1988

Laser instrumentation: a microtenaculum for laser tissue fusion.

Precise tissue apposition and edge eversion are essential for tissue fusion with the CO2 laser. A microtenaculum has been designed to accomplish this without the placement of horizontal mattress stay sutures. This instrument permits tissue orientation and approximation for primary laser fusion as well as for the repair of small gaps present after initial welding.

Humans↗
PubMed1993

Comparison of the flashlamp pulsed dye laser with the argon tunable dye laser with robotized handpiece for facial telangiectasia.

This prospective study compares the efficacy, side effects, and patient acceptance of the flashlamp pulsed dye laser (FPDL) with the argon tunable dye laser with robotized handpiece (ATDL/H) for facial telangiectasias. Seventeen adult patients with bilaterally symmetric facial telangiectasias were enrolled. The right cheek on each patient was treated in one session with the FPDL at a fluence of 6.0-6.75 J/cm2 and a spot size of 5 mm. The left cheek was treated at the same session with the ATDL/H at a power of 1 W, a fluence of 26-27 J/cm2, and a hexagonal treatment area of 13 mm (127 individual 1 mm spots grouped mechanically by the handpiece). Patients were evaluated subjectively and by the investigators at 2, 4, and 6 weeks for blistering, swelling, bruising, changes in pigment, scarring, overall efficacy, and patient preference. Average treatment times were 5.4 minutes for FPDL and 9.4 minutes for ATDL/H. Blistering, crusting, and discomfort were completely resolved on both sides by week 2 in all patients. Bruising occurred in all patients with FPDL but had resolved in 62.5% of patients at 2 weeks and 100% at 4 weeks. There was no bruising with ATDL/H. Postinflammatory hyperpigmentation was much more prominent with FPDL but had resolved in 88% of cases by week 6. As rated by the investigators 100% of the FPDL treated areas showed excellent clearing of telangiectasias, compared with 47% of ATDL/H treated areas.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed2005

Treatment of port wine stains with photodynamic therapy, using pulsed dye laser as a light source, compared with pulsed dye laser alone: a pilot study.

BACKGROUND AND OBJECTIVES: Laser-induced photo thermal damage has been combined with photodynamic therapy (PDT) using a systemic photosensitiser to treat vascular lesions. The efficacy of PDT using systemic 5-aminolaevulinic acid (5-ALA) as the photosensitiser and pulsed dye laser (PDL) as the light source in port wine stains (PWS) is unknown. STUDY DESIGNS/MATERIALS AND METHODS: We conducted an internally controlled pilot study comparing the efficacy of PDT using PDL as a light source, to PDL alone in the treatment of PWS. RESULTS: The PWS improved slightly in all patients but no significant difference was found between the three treatment arms in terms of lesional lightening or incidence and severity of side effects. CONCLUSIONS: There was no evidence of increased efficacy of PDT using PDL as a light source compared to PDL alone. There was also no significant difference in adverse events. Further studies using different treatment regimens over longer periods of time may be warranted.

Adult↗