Search results for "structures"
showing 10 items of 4815 documents
Howard–Dolman stereovision test at different opponent colour stimuli
2011
The purpose of this study was to investigate visual depth perception of real physical colour stimuli with red-green and blue-yellow opponency. We modified the Howard–Dolman stereotest where subjects should determine the closer of two bars emitting the light of definite colour placed in front of a CRT monitor served as colour background. Two-alternative forced-choice paradigms were used to determine depth perception threshold values. Thresholds close to 5–10 arcsec for luminance and colour contrast stimuli were revealed both for red-green and blue-yellow stimuli. A term, stereosensitivity – a reciprocal magnitude of the stereothreshold – was introduced to separately analyse luminance and col…
Simple Configuration Effects on Eye Movements in Horizontal Scanning Tasks
2015
When reading text, observers alternate periods of stable gaze (fixations) and shifts of gaze (saccades). An important debate in the literature concerns the processes that drive the control of these eye movements. Past studies using strings of letters rather than meaningful text ('z-reading') suggest that eye movement control during reading is, to a large extent, controlled by low-level image properties. These studies, however, have failed to take into account perceptual grouping processes that could drive these low-level effects. We here study the role of various grouping factors in horizontal scanning eye movements, and compare these to reading meaningful text. The results show that sequen…
VisuMax®femtosecond laser for corneal refractive surgery
2008
Femtosecond lasers are increasingly present in ophthalmologic surgical theaters for a variety of reasons. These include faster and better visual outcomes, increased accuracy and predictability for corneal flap thickness in laser in situ keratomileusis procedures. Recent applications of modern femtosecond lasers have broadened the range of uses: keratoplasty, intrastromal segment insertion and even glaucoma and presbyopia surgery. This device profile provides an overview of the advantages of femtosecond lasers in ophthalmic surgery, paying special attention to the new VisuMax® femtosecond laser from Zeiss/Meditec.
Beals–Hecht syndrome and choroidal neovascularization
2010
Purpose: To describe a case of choroidal neovascularization (CNV) in a female diagnosed with Beals–Hecht syndrome. Methods: A retrospective, interventional case is described in a 26-year-old female complaining of metamorphopsia and visual loss in her left eye (counting fingers). The fluorescein angiogram and the optical coherence tomography supported the diagnosis of CNV. Intravitreal ranibizumab was administered. Results: After the third intravitreal ranibizumab, her visual acuity improved to 0.8 and the morphology of the macular area was restored. Conclusions: To our knowledge this is the first report of CNV in Beals–Hecht syndrome treated with ranibizumab. Self-monitoring by periodically…
Is It Easy to Synchronize Our Minds When We Are Forced to Cooperate?
2019
There is increasing scientific interest in elucidating the biological mechanisms underlying cooperative behaviors. Humans have developed a high degree of complexity in their cooperativity, which has been defined as hyper-cooperativity. An interesting biological marker to study how two individuals are emotionally linked when they cooperate is their psychophysiological synchronization (the overlapping of signals as indicators of Autonomous Nervous System activation). Hence, the main aim of this study was to explore participants&rsquo
Nuevos factores de riesgo para la progresión del Glaucoma
2015
INTRODUCCIÓN El Glaucoma es una neuropatía óptica de desarrollo progresivo que afecta a 90 millones de habitantes del planeta, siendo la forma clínica conocida como glaucoma primario de ángulo abierto (GPAA) la primera causa de ceguera irreversible en los países desarrollados. Los factores de riesgo para su desarrollo incluyen en primer lugar la presión intraocular, pero también la edad, la raza, la predisposición familiar, el espesor corneal central, miopía y presión de perfusión ocular han sido descritos como importantes en el desarrollo y/o progresión del glaucoma, entre otros. No obstante, hay evidencia acerca de la existencia de otros factores de riesgo, los denominados emergentes, así…
CLINICAL AND IMAGING FINDINGS OF RARE SYMPTOMATIC GIANT KILLIAN-JAMIESON DIVERTICULUM
2014
Learning objectives Background Findings and procedure details Conclusion Personal information References
The functional significance of colour polymorphism in the European common wall lizard (Podarcis muralis)
2021
Colour polymorphisms, the coexistence of two or more colour morphs of a species within a population, have long fascinated evolutionary biologists interested in the mechanisms generating and maintaining phenotypic variation in nature. The functional significance of colour polymorphisms (i.e. their adaptive value) is often linked to the selective mechanisms responsible for their maintenance over time. In lizards, the hypothesis that colour morphs may reflect alternative reproductive strategies involving differential sociosexual behaviour and/or alternative reproductive strategies has come to dominate the field. Wall lizards (family Lacertidae, genus Podarcis), with several geographically dist…
Prevalence and risk factors for myopia and other refractive errors in an adult population in southern India.
2018
PURPOSE: To investigate prevalence and risk factors for myopia, hyperopia and astigmatism in southern India. METHODS: Randomly sampled villages were enumerated to identify people aged ≥40 years. Participants were interviewed for socioeconomic and lifestyle factors and attended a hospital-based ophthalmic examination including visual acuity measurement and objective and subjective measurement of refractive status. Myopia was defined as spherical equivalent (SE) worse than -0.75 dioptres (D), hyperopia as SE ≥+1D and astigmatism as cylinder <-0.5. RESULTS: The age-standardised prevalences of myopia, hyperopia and astigmatism were 35.6% (95% CI: 34.7-36.6), 17.0% (95% CI: 16.3-17.8) and 32.6 (…
Artificial pupil versus contralateral balanced contact lens fit for presbyopia correction
2018
Purpose: To assess and compare the effects of contact lens-based artificial pupil design and contralateral balanced multifocal contact lens combination (CBMCLC) on visual performance. Methods: This randomized crossover study conducted at the University of Valencia, Spain included 38 presbyopic patients using an artificial pupil contact lens in the nondominant eye and a CBMCLC. After a month of lens wear, the binocular distance visual acuity (BDVA), binocular near visual acuity (BNVA), defocus curve, binocular distance, and near contrast sensitivity and near stereoacuity (NSA) were measured under photopic conditions (85 cd/m2). Moreover, BDVA and binocular distance contrast sensitivity were …