1,720,971 research outputs found
Broad Beam vs. Flying Spot Excimer Laser: Refractive and Videokeratographic Outcomes of two Different Ablation Profiles after Photorefractive Keratectomy
No full textPURPOSE:
To assess the refractive outcomes and videokeratographic patterns in photorefractive keratectomy (PRK) of two last-generation excimer lasers: broad beam and flying spot lasers.
METHODS:
Forty eyes were treated for a mean myopic correction of -5.59+/-2.17 D with a Ladarvision excimer laser (Autonomous Technology Corp). We compared the refractive outcomes and the videokeratographic patterns with those of 40 eyes treated with the Summit Apex Plus laser (Summit Technology Inc) for a mean myopic correction of -5.60+/-2.24 D.
RESULTS:
During the 6-month follow-up, we found no significant difference in uncorrected and spectacle-corrected visual acuity, haze grade, regularity index, or decentration. The eyes treated by Ladarvision showed a lower refractive error at 1 month (P = .04), a lower incidence of central islands at 1 (P = .003) and 3 months (P = .04), a wider mean effective ablation area at 1 (P = .0004), 3 (P = .0000009), and 6 months (P = .0000000004), a less steep ablation edge at 1 (P = .0026), 3 (P = .015), and 6 months (P = .011).
CONCLUSIONS:
The small beam excimer laser provides better videokeratographic outcomes, which lead to quicker refractive stability and better visual performance
Mechanical vs. alcohol epithelial removal during photorefractive keratectomy.
No full textPURPOSE:
To assess whether a chemical debridement method for excimer laser photorefractive keratectomy may lead to better refractive and visual results than the standard method which involves the use of a blunt blade to scrape off the epithelium.
METHODS:
Ninety-three eyes with a mean attempted correction of -5.72 +/- 2.47 D were debrided using a surgical microsponge after epithelial melting by 20% ethanol solution applied for 20 seconds, and treated by PRK. Results were compared to those from 97 eyes with a mean attempted correction of -6.05 +/- 2.46 D, deepithelialized using a Desmarres blade.
RESULTS:
Debridement time was faster in the eyes where alcohol was used (P = .04). During a 6-month follow-up, we found no significant differences in refractive error, uncorrected, and spectacle-corrected visual acuity. However, haze rates at were lower (1 month, P = .04), and corneal regularity index was better (3 months, P = .01) in the eyes deepithelialized using alcohol.
CONCLUSIONS:
Epithelial debridement using a 20% alcohol solution was faster to perform, and provided sharper edges and a smoother Bowman's layer surface than mechanical debridement. This may explain the better results in terms of haze and corneal regularity
Short-Term Effects of a Novel Eye Mask Producing Heat and Vibration for the Treatment of Meibomian Gland Dysfunction: A Pilot Study
No full textPurpose. To investigate the short-Term effects on tear film parameters and ocular symptoms of a novel eye mask producing heat and vibration developed for the treatment of dry eye disease owing to meibomian gland dysfunction (MGD). Methods. This is a pilot study including the first 20 consecutive patients (6 males, 14 females; mean age 52.4 ± 16.8 years) who were treated with a novel eye mask producing heat (42°) and vibration (up to 20 Hz) (Activa, SBS Sistemi, Turin, Italy) for 15 minutes. The treatment incorporates 2 phases in the following chronological order: 5 minutes of heating (phase I); 10 minutes of combination of heating and vibration (phase II). Noninvasive ocular surface examination was carried out before (T0) and 30 minutes after the mask session (T1) by means of Idra (SBS Sistemi, Turin, Italy) for the measurement of noninvasive break-up time (NIBUT) and lipid layer thickness (LLT). Patients' satisfaction after treatment was ascertained by asking the patients whether they perceived improvement from their baseline symptoms according to a 5-grade scale: none = 0; trace = 1; mild = 2; moderate = 3; high = 4. Results. All patients completed regularly the mask session and no device-related adverse events were noted. NIBUT improved significantly from T0 to T1 (from 7.2 ± 1.8 s to 8.1 ± 2.1; P = 0.014). In parallel, also LLT improved from from T0 to T1 (72.5 ± 13.9 nm to 83.1 ± 16.1; P = 0.016). Seven patients (35% of the total) had a moderate satisfaction (grade 3) while 13 patients (65%) had a high satisfaction (grade 4) with treatment. Conclusions. This eye mask represents a novel well tolerated tool in the armamentarium of MGD treatments. Thirty minutes after the session, NIBUT and LLT increased significantly; furthermore, all patients reported an improvement of discomfort symptoms with a moderate to high satisfaction with treatment
Intense Pulsed Light for the Treatment of Dry Eye Owing to Meibomian Gland Dysfunction
No full textDry eye disease (DED) is an increasingly common condition and one of the most common complaints of patients. The vast majority of DED is caused by the so-called "evaporative" subtype, that is mainly caused by meibomian gland dysfunction (MGD). Intense pulsed light (IPL) devices employ high intensity pulses of polychromatic lights with a broad range of wavelength (515-1200 nm). IPL treatment has been utilized for years in the field of dermatology, and then its use was applied to ophthalmology for the treatment of MGD. Recently, a new device employing IPL was specifically designed for the periocular application. This procedure determines the thermal selective coagulation and ablation of superficial blood vessels and telangiectasias of the eyelids skin, reducing the release of inflammatory mediators and tear cytokines levels, and improving meibomian glands outflow. IPL treatment is noninvasive and easy to perform, lasts for only a few minutes and can be conducted in an office setting. In the present study, 19 patients underwent 3 sessions of IPL treatment. After treatment, both mean noninvasive break-up time and lipid layer thickness grade significantly increased, as a result of an improvement of tear film stability and quality, respectively. Conversely, no statistically significant changes were found for meibomian gland loss and tear osmolarity. Furthermore, the vast majority of the treated patients (17/19; 89.5% of the total) perceived an improvement of their ocular discomfort symptoms after IPL treatment. Although IPL treatment provides an improvement of both ocular surface parameters and ocular discomfort symptoms after one cycle of three sessions, regular repeated treatments are usually required to maintain the persistence over the time of its beneficial effects
Effetti della infusione in camera anteriore di mannitolo al 2,5% nell'intervento di cataratta con impianto di cristallino artificiale: risultati preliminari
No full text
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
- …
