1,720,969 research outputs found
The Slit Lamp and Sodium Fluorescein: Their Use and Benefits
Get PDFAims: (i) Gather data from optometrists worldwide on their use of the slit lamp and their use of sodium fluorescein. (ii) To measure the effectiveness of performing slit lamp examination and instillation of sodium fluorescein on every patient attending for an eye examination (iii) To measure the number of clinical signs seen when performing polarised biomicroscopy using a circular polariser filter. Methods: (i) A questionnaire was sent out to optometrists in different parts of the world asking questions concerning the use of the slit lamp and sodium fluorescein. (ii) Ninety-six patients were examined, and all patients had a complete slit-lamp examination, and every patient had sodium fluorescein instilled on their eye. (iii) The same 96 patients' cornea, iris and crystalline lens were examined using a circular polariser filter. Results: (i) The majority of the survey respondents stated that they used the slit lamp on 75% or more of their non-contact lens patients. However, when asked about the use of sodium fluorescein, most respondents stated that they used it on only 25% or less of their patients. (ii) Using the slit lamp on every patient showed clinical signs in between 86%-95% of the patients. Using sodium fluorescein on every patient showed clinical signs in 54% of patients. (iii) Using the circular polariser on every patient enhanced the view of clinical signs in 29% of patients. Conclusions: Whilst the use of the slit lamp is high on non-contact lens wearers, the use of sodium fluorescein is relatively low. Using the slit lamp on all patients attending an eye exam is effective as numerous signs can be seen. The circular polariser filter can be helpful in routine practice but only for those patients who already have clinical signs
Visual performance in myopic patients wearing daily-disposable multifocal soft contact lenses
Get PDFThe ageing population will become one of the biggest issues affecting Singapore in the near future. Ophthalmic practitioners will need to be ready to deal with an increased prevalence of glaucoma, cataract, age related maculopathy and even presbyopia. As presbyopes lose their ability to accommodate at near vision, visual aids such as progressive lenses, bifocal lenses, reading glasses, monovision contact lenses and multifocal contact lenses are prescribed to help them with reading difficulties and improve their daily lives. Interestingly, an international survey in 2011 revealed zero percent soft multifocal contact lenses was prescribed in Singapore for presbyopia correction. Although there are improvements in multifocal lens design and material, no new research being conducted to investigate the presbyopic lens fitting status in Singapore. Nonetheless, recent studies have shown an increased in multifocal contact lenses prescribing trends, perhaps reflecting not just the availability of newer multifocal contact lenses, but also improvement in practitioners’ confidence and knowledge in multifocal contact lenses. However, in spite of the available guides on choosing multifocal contact lenses, there is no comprehensive way to help the practitioner in selecting the best option for an individual. As such, an examination of the simplest way of predicting the most suitable multifocal lens for a patient will only enhance and add to the current evidence available. A survey was conducted to understand the Singaporean practitioners’ attitude towards soft multifocal lenses and its prescribing trend. In this survey, an increase in the rate of soft multifocal contact lens fitting was observed, the perception of the unavailability of an ‘ideal’ multifocal contact lens, and increased chair time in fitting soft multifocal contact lenses were identified as significant barriers. However, enablers such as the increased in practitioners’ motivation, confidence and proactiveness in fitting soft multifocal contact lenses were gathered. Additionally, this study aimed to compare the relative performance of three daily-replacement soft contact lenses for presbyopic correction in an optometric practice population in Singapore. The three daily-disposable multifocal contact lenses included in this study were 1-day Acuvue® Moist Brand Multifocal Contact Lenses for Presbyopia (Johnson & Johnson Vision Care, Jacksonville, FL), Clariti 1-day Mulitfocal (Cooper Vision, NY) and Dailies AquaComfort Plus Multifocal (Alcon, Fort worth, TX). In this crossover study design, 35 presbyopic participants with myopia were fitted in a random order with three different types of multifocal contact lens. After 1 month, visual performance was quantified by high contrast distance, intermediate and near visual acuity, defocus curve under photopic and mesopic conditions, reading speed, Near Activity Visual Questionnaire rating and Photographic questionnaire for Photic Phenomena. The results showed comparable levels of binocular distance, intermediate and near visual acuity achieved with the three different types of multifocal contact lens at 1-month follow up. However, a better distance acuity at distance under mesopic condition for AquaComfortPlus. In terms of subjective participant lens preference, nine participants (26%) preferred Moist multifocal, 16 participants (46%) preferred Clariti multifocal and 10 participants (28%) preferred AquaComfortPlus multifocal. However, lens preference was not related to demographic factors relating to age, gender, refractive error and the magnitude of reading addition or physiological characteristic such as pupil size. In terms of the performance of participants with their preferred lens when observing the defocus curve under mesopic condition, it emerged that there was an interaction between lens types and acuity at different levels of defocus. From this, it seems that lens preference may perhaps be driven by a change in visual experience that only manifested in low illumination conditions, suggesting it may be important to conduct objective measure such as visual acuity under mesopic condition when fitting modern-day multifocal contact lenses. It remains a hope for the future that new clinical tests or more diverse lens designs would be valuable to help the practitioner to improve the chances of first time success when fitting a multifocal contact lens for presbyopic correction
Novelty Optimisation Techniques For Myopia Assessment & Management
Get PDFThis thesis hoped to inform the practice of future individual myopia management. All myopia risk factors across global ethnic regions must be considered, instead of relying on the most widely used averaged parameters, towards the development of growth model tools. There could be possible crucial cut points of near phoria development at specified age ranges, earlier and later in life, suggesting this myopia risk factor should be measured alongside other primary outcome parameters important for treatment efficacy. Other notable human lifespan findings included: emmetropic and female patients attended eye examinations more frequently; females exhibited higher levels of near phoria and myopia; myopes were more esophoric than emmetropes, progressive myopes were more esophoric than both myopes and emmetropes, and were less likely to increase in exophoria with age. The presumed design optimisation, regarding daily CE-marked optical myopia control strategies, was based on the possible mechanism behind myopic retinal defocus (blur) and accommodative lag in myopia development and progression. Contact lens designs could have an inherent characteristic for their treatment effect in the temporal retina at 30° and J0 astigmatic component. Multifocal contact lenses for myopia control significantly impacted glare, but did not affect contrast sensivitiy differently than standard lenses, and would offer equally acceptable treatment compliance and qualifty of life expectations. Specialty instrumentation for measuring primary outcomes (refraction and axial length) should be used interchangeably for myopia control studies. This was confirmed between the gold standard biometers, IOLMaster 700 and IOLMaster 500, for the key parameters of axial length, anterior chamber depth and corneal topography, where discrepancies in white-to-white corneal diameter values, following MiSight and NaturalVue contact lens wear, were minimal and clinically irrelevant. Further novel discoveries proved myopia control contact lenses were viable non-invasive sampling vehicles for human dopamine detection. Thus, the thesis probed the viability of novelty applications of such “labelled” and/or gold standard medical devices and instrumentations towards treating individual myopic patients and highlighted that appropriate global myopia management and standardisation remain poor
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Cirugía reafractaria tipo LASIK con láser de femtosegundo: eficacia y seguridad
Get PDFTesis de la Universidad Complutense de Madrid, Escuela Universitaria de Óptica, leída el 09-02-2012En los últimos 20 años se ha extendido la corrección de la ametropía por medio de cirugía refractiva. De los diferentes procedimientos de cirugía refractiva es el LASIK con láser de excimero la técnica quirúrgica más frecuente debido a la mayor rapidez en la recuperación visual, menos molestias postoperatorias, menor incidencia de aparición de cicatrices o turbidez corneal. A pesar de los buenos resultados, este procedimiento no está exento de complicaciones algunas de ellas relacionados con la creación del colgajo corneal por medio de un microqueratomo mecánico (MM).
La necesidad de disminuir los riesgos asociados a la creación del colgajo corneal ha llevado al desarrollo de MM más seguros y a la investigación de métodos de corte lamelar distintos como es el caso del láser de femtosegundo (FS).
Mediante el diseño de diferentes estudios en los cuales se ha incluido sujetos representativos de las diferentes poblaciones objeto estudio y, el análisis estadístico de los resultados, concluimos que: 1) Tanto el LASIK asistido con el láser de FS como el LASIK realizado con MM son procedimientos efectivos y seguros para corregir la hipermetropía (de hasta +6.50 dioptrías), aunque se alcanza una mejor corrección refractiva de la hipermetropía con el FS que con el MM, si bien ambos tienen una seguridad similar. 2) Tanto el LASEK con o sin MMC como el FSBK son procedimientos seguros y eficaces para corregir miopía moderada (de hasta -12,50 dioptrías). La recuperación visual es más lenta tras LASEK siendo los resultados visuales y refractivos ligeramente mejores con FSBK a los 3 meses de seguimiento. 3) La DLK es más frecuente tras LASIK llevado a cabo con láser de IntraLase de FS que con LASIK con el MM.Depto. de Optometría y VisiónFac. de Óptica y OptometríaTRUEpu
Variations on the Author
Get PDF“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
Get PDFWe 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
Get PDFWe 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
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