Search results for "Lasers"
showing 10 items of 316 documents
Reproducibility of digital image analysis for measuring corneal haze after myopic photorefractive keratectomy.
1997
Purpose To evaluate the usefulness of digital image analysis for quantifying corneal haze by determining the reproducibility of its measurements at the corneal plane. Methods In a prospective study, 20 randomly selected eyes that had undergone myopic photorefractive keratectomy were photographed focusing the slit beam on their anterior corneal surface. Each photograph was examined using computer image analysis techniques that detect the edge of the reticular pattern of the image. Quantification of the difference between two areas, treated and adjacent untreated cornea, each containing 3,750 pixels with a resolution of 256 gray levels, was performed. Intra-analyzer variation was determined b…
Direct Objective Quantification of Corneal Haze after Excimer Laser Photorefractive Keratectomy for High Myopia
1996
Purpose: The purpose of the study is to measure regional distribution differences in corneal haze after excimer laser photorefractive keratectomy for high myopia. Methods: The authors developed computerized gradient edge detectors with which were analyzed digitized anterior slit-lamp photographs of 40 eyes, an average of 21.0 plus or minus 14.5 weeks after photorefractive keratectomy for high myopia (−6 to −22 diopters). A treated area and an adjacent untreated area on the anterior corneal surface, each containing six regions, were quantified, and the difference was correlated with various parameters. Results: Mean differences between scarred and clear areas for haze grade 0.5, 1.0, 2.0, 3.…
Mesopic contrast sensitivity function after excimer laser photorefractive keratectomy.
2002
ABSTRACT PURPOSE: To evaluate contrast sensitivity under mesopic conditions in patients who had undergone uncomplicated excimer laser photorefractive keratectomy (PRK) for myopia. METHODS: Monocular contrast sensitivity function was measured with the Stereo Optical ?A.C.T. chart in 26 patients who had received PRK using the Nidek EC-5000 excimer laser system. Mean preoperative refractive error was -6.23 ? 1.69 D (range, -4.00 to -8.25 D); postoperatively, mean refractive error was -0.36 ? 0.58 D (range, -0.75 to +0.50 D). Contrast sensitivity function was measured 6 months after surgery using four different chart luminances: 85, 5.0, 2.5, and 0.1 cd/m2, the first being a photopic level and …
Excimer laser photorefractive keratectomy for high myopia
1995
Abstract One hundred and thirty-three eyes of 103 patients had photorefractive keratectomy with a slit scan mode excimer laser for myopia ranging from −6.00 to −22.00 diopters (D). The epithelium was removed with 20% ethanol, and the ablation was done with a tapered profile surrounding the optical zone. Patients were divided into two groups based on preoperative myopia: Group A, −6.00 D to −12.00 D (88 eyes); Group B, −12.50 D to −22.00 D (45 eyes). In Group A, mean preoperative refraction was −9.59 ± 1.79 D. Mean postoperative refraction was −0.29 ± 1.47 D at one month, −0.85 ± 1.68 D at three months, −1.17 ± 2.04 D at six months, and −0.56 ± 0.74 D at one year. Anterior stromal haze was g…
Sensitivity of laser-evoked potentials versus somatosensory evoked potentials in patients with multiple sclerosis
2003
Somatosensory evoked potentials (SEPs) play a less important role in the diagnosis of multiple sclerosis (MS) than visually evoked potentials. Since standard SEPs only reflect the dorsal column function, we now investigated spinothalamic tract function in patients with MS using laser-evoked potentials (LEPs).LEPs to thulium laser stimuli (3ms, 540 mJ, 5mm diameter) were recorded from 3 midline positions (Fz, Cz, Pz) in 20 patients with MS, and 6 patients with possible but unconfirmed MS. Peak latencies and peak-to-peak amplitude of the vertex potential negativity (N2) and positivity (P2) were evaluated and compared with normative values from 22 healthy control subjects. Median and tibial ne…
Histological differences in the adherence of connective tissue to laser-treated abutments and standard abutments for dental implants. An experimental…
2017
Background The goal of the current study is to assess the difference in connective tissue adherence to laser microtextured versus machined titanium abutments. Material and Methods Six patients were selected and each of them received 2 implants, one combined with a laser treated abutment and one with a machined abutment. After three months, the abutments were retrieved together with their surrounding gingival tissue for histological analysis. Qualitative and quantitative evaluation of microscopical images was performed to assess the presence or absence of adherence between the soft tissues and the abutment, and the percentage of soft tissue adhered to the two different surfaces. Results Inti…
Ranibizumab for Branch Retinal Vein Occlusion Associated Macular Edema Study (RABAMES): six-month results of a prospective randomized clinical trial
2014
Purpose To compare standard-of-care grid laser photocoagulation versus intravitreal ranibizumab (IVR) versus a combination of both in the treatment of chronic (>3 months) macular oedema secondary to branch retinal vein occlusion. Methods Prospective, randomized, multicentre clinical trial. Thirty patients with a best-corrected visual acuity (BCVA) between 20/320 and 20/40 were randomized 1:1:1 to receive grid laser or three monthly injections of 0.5 mg IVR or both followed by 3 months of observation. Results Mean change from baseline BCVA at month 6 was +2 letters [laser; 0.04 logMAR, 95% confidence interval (−0.17; 0.25)], +17 letters [IVR; 0.34 (0.19; 0.5)] and +6 letters [combination; 0.…
Single versus double femtosecond laser pass for incomplete laser in situ keratomileusis flap in contralateral eyes: Visual and optical outcomes
2011
Purpose To evaluate visual acuity, refractive outcomes, and anterior corneal higher-order aberrations (HOAs) after myopic laser in situ keratomileusis (LASIK) with uneventful single femtosecond laser pass versus double pass performed for intraoperative suction loss. Setting Private refractive surgery center, Valencia, Spain. Design Cohort study. Methods After the LASIK flap was created with a single pass of an Intralase femtosecond laser in 1 eye and a double pass in the fellow eye, the ablation was performed with a Visx S2 laser. At 12 months, the refraction, uncorrected (UDVA) and corrected (CDVA) distance visual acuities, and anterior corneal HOAs were measured with 4.0 mm and 6.0 mm pup…
The Effectiveness of Laser-Assisted Surgical Excision of Leukoplakias and Hyperkeratosis of Oral Mucosa: A Case Series in A Group of Patients
2019
Introduction: In the different branches of dentistry, the use of laser to solve different clinical situations is increasing due to numerous advantages that have been studied in literature since the 70s. Leucoplakia and hyperkeratosis can benefit from laser-assisted treatment. In most cases biopsy sampling, histological examination and, if no malignant cells are present, the follow-up is needed. However, even if the lesion is free of dysplasia patients often ask to eliminate these white spots that are always a cause of concern. Aim: From these numerous requests comes the idea of setting up a laser-assisted protocol as less invasive as possible to be offered to patients. The aim of the study …
Differential effects on the laser evoked potential of selectively attending to pain localisation versus pain unpleasantness
2004
Abstract Objective : To determine the effects on the laser evoked potential (LEP) of selectively attending to affective (unpleasantness) versus sensory-discriminative (localisation) components of pain. Methods : LEPs, elicited by painful CO 2 laser stimulation of two areas of the right forearm, were recorded from 62 electrodes in 21 healthy volunteers, during three tasks that were matched for generalised attention: Localisation (report stimulus location), Unpleasantness (report stimulus unpleasantness), Control (report pain detection). LEP components are named by polarity, latency, and electrode. Results : N300-T7 peak amplitude was significantly greater during Localisation than Unpleasantn…