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1.
Phys Rev Lett ; 122(17): 174102, 2019 May 03.
Artículo en Inglés | MEDLINE | ID: mdl-31107096

RESUMEN

Excitable waves arise in many spatially extended systems of either a biological, chemical, or physical nature due to the interplay between local reaction and diffusion processes. Here we demonstrate that similar phenomena are encoded in the time dynamics of an excitable system with two, hierarchically long delays. The transition from 1D localized structures to curved wave segments is experimentally observed in an excitable semiconductor laser with two feedback loops and reproduced by numerical simulations of a prototypical model. While closely related to those found in 2D excitable media, wave patterns in delayed systems exhibit unobserved features originating from causality related constraints. An appropriate dynamical representation of the data uncovers these phenomena and permits us to interpret them as the result of an effective 2D advection-reaction-diffusion process.

2.
Phys Rev Lett ; 120(17): 173901, 2018 Apr 27.
Artículo en Inglés | MEDLINE | ID: mdl-29756835

RESUMEN

Experimental evidence of an absorbing phase transition, so far associated with spatiotemporal dynamics, is provided in a purely temporal optical system. A bistable semiconductor laser, with long-delayed optoelectronic feedback and multiplicative noise, shows the peculiar features of a critical phenomenon belonging to the directed percolation universality class. The numerical study of a simple, effective model provides accurate estimates of the transition critical exponents, in agreement with both theory and our experiment. This result pushes forward a hard equivalence of nontrivial stochastic, long-delayed systems with spatiotemporal ones and opens a new avenue for studying out-of-equilibrium universality classes in purely temporal dynamics.

3.
Cochrane Database Syst Rev ; 4: CD003303, 2018 04 17.
Artículo en Inglés | MEDLINE | ID: mdl-29664159

RESUMEN

BACKGROUND: The purpose of low-vision rehabilitation is to allow people to resume or to continue to perform daily living tasks, with reading being one of the most important. This is achieved by providing appropriate optical devices and special training in the use of residual-vision and low-vision aids, which range from simple optical magnifiers to high-magnification video magnifiers. OBJECTIVES: To assess the effects of different visual reading aids for adults with low vision. SEARCH METHODS: We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (which contains the Cochrane Eyes and Vision Trials Register) (2017, Issue 12); MEDLINE Ovid; Embase Ovid; BIREME LILACS, OpenGrey, the ISRCTN registry; ClinicalTrials.gov and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP). The date of the search was 17 January 2018. SELECTION CRITERIA: This review includes randomised and quasi-randomised trials that compared any device or aid used for reading to another device or aid in people aged 16 or over with low vision as defined by the study investigators. We did not compare low-vision aids with no low-vision aid since it is obviously not possible to measure reading speed, our primary outcome, in people that cannot read ordinary print. We considered reading aids that maximise the person's visual reading capacity, for example by increasing image magnification (optical and electronic magnifiers), augmenting text contrast (coloured filters) or trying to optimise the viewing angle or gaze position (such as prisms). We have not included studies investigating reading aids that allow reading through hearing, such as talking books or screen readers, or through touch, such as Braille-based devices and we did not consider rehabilitation strategies or complex low-vision interventions. DATA COLLECTION AND ANALYSIS: We used standard methods expected by Cochrane. At least two authors independently assessed trial quality and extracted data. The primary outcome of the review was reading speed in words per minute. Secondary outcomes included reading duration and acuity, ease and frequency of use, quality of life and adverse outcomes. We graded the certainty of the evidence using GRADE. MAIN RESULTS: We included 11 small studies with a cross-over design (435 people overall), one study with two parallel arms (37 participants) and one study with three parallel arms (243 participants). These studies took place in the USA (7 studies), the UK (5 studies) and Canada (1 study). Age-related macular degeneration (AMD) was the most frequent cause of low vision, with 10 studies reporting 50% or more participants with the condition. Participants were aged 9 to 97 years in these studies, but most were older (the median average age across studies was 71 years). None of the studies were masked; otherwise we largely judged the studies to be at low risk of bias. All studies reported the primary outcome: results for reading speed. None of the studies measured or reported adverse outcomes.Reading speed may be higher with stand-mounted closed circuit television (CCTV) than with optical devices (stand or hand magnifiers) (low-certainty evidence, 2 studies, 92 participants). There was moderate-certainty evidence that reading duration was longer with the electronic devices and that they were easier to use. Similar results were seen for electronic devices with the camera mounted in a 'mouse'. Mixed results were seen for head-mounted devices with one study of 70 participants finding a mouse-based head-mounted device to be better than an optical device and another study of 20 participants finding optical devices better (low-certainty evidence). Low-certainty evidence from three studies (93 participants) suggested no important differences in reading speed, acuity or ease of use between stand-mounted and head-mounted electronic devices. Similarly, low-certainty evidence from one study of 100 participants suggested no important differences between a 9.7'' tablet computer and stand-mounted CCTV in reading speed, with imprecise estimates (other outcomes not reported).Low-certainty evidence showed little difference in reading speed in one study with 100 participants that added electronic portable devices to preferred optical devices. One parallel-arm study in 37 participants found low-certainty evidence of higher reading speed at one month if participants received a CCTV at the initial rehabilitation consultation instead of a standard low-vision aids prescription alone.A parallel-arm study including 243 participants with AMD found no important differences in reading speed, reading acuity and quality of life between prism spectacles and conventional spectacles. One study in 10 people with AMD found that reading speed with several overlay coloured filters was no better and possibly worse than with a clear filter (low-certainty evidence, other outcomes not reported). AUTHORS' CONCLUSIONS: There is insufficient evidence supporting the use of a specific type of electronic or optical device for the most common profiles of low-vision aid users. However, there is some evidence that stand-mounted electronic devices may improve reading speeds compared with optical devices. There is less evidence to support the use of head-mounted or portable electronic devices; however, the technology of electronic devices may have improved since the studies included in this review took place, and modern portable electronic devices have desirable properties such as flexible use of magnification. There is no good evidence to support the use of filters or prism spectacles. Future research should focus on assessing sustained long-term use of each device and the effect of different training programmes on its use, combined with investigation of which patient characteristics predict performance with different devices, including some of the more costly electronic devices.


Asunto(s)
Dispositivos Ópticos/normas , Lectura , Auxiliares Sensoriales , Baja Visión/rehabilitación , Personas con Daño Visual/rehabilitación , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Niño , Anteojos , Humanos , Lentes , Degeneración Macular/complicaciones , Persona de Mediana Edad , Ensayos Clínicos Controlados Aleatorios como Asunto , Baja Visión/etiología , Agudeza Visual
4.
Phys Rev Lett ; 118(12): 123901, 2017 Mar 24.
Artículo en Inglés | MEDLINE | ID: mdl-28388183

RESUMEN

Complex optical networks containing one or more gain sections are investigated, and the evidence of lasing action is reported; the emission spectrum reflects the topological disorder induced by the connections. A theoretical description compares well with the measurements, mapping the networks to directed graphs and showing the analogies with the problem of quantum chaos on graphs. We show that the interplay of chaotic diffusion and amplification leads to an emission statistic with characteristic heavy tails: for different topologies, an unprecedented experimental demonstration of Lévy statistics expected for random lasers is here provided for a continuous-wave pumped system. This result is also supported by a Monte Carlo simulation based on the ray random walk on the graph.

5.
Ophthalmologica ; 238(1-2): 44-51, 2017.
Artículo en Inglés | MEDLINE | ID: mdl-28641290

RESUMEN

PURPOSE: To evaluate the long-term outcomes of intravitreal anti-vascular endothelial growth factor (VEGF) drugs with a pro re nata (PRN) regimen for the treatment of choroidal neovascularization (CNV) secondary to angioid streaks (AS). METHODS: This is a retrospective, multicenter, noncomparative case series of consecutive AS eyes affected by treatment-naïve CNV. A complete ophthalmologic examination was performed every 30-45 days after the loading phase, including fluorescein angiography and/or optical coherence tomography. RESULTS: In all, 52 eyes of 39 patients were treated with intravitreal bevacizumab and/or ranibizumab and followed up for a mean of 33.8 months. The best corrected visual acuity at baseline was 20/40, and it deteriorated by an average of 6.8 ETDRS letters per year (p < 0.001). We performed an average of 5.1, 6.5, and 6.8 injections at the 1-, 2-, and 3-year follow-up, respectively. CONCLUSIONS: Intravitreal anti-VEGF drugs in a PRN regimen with close monitoring appear to slow the progression of CNV in AS, but they do not prevent the affected eyes from progressive visual loss.


Asunto(s)
Estrías Angioides/complicaciones , Bevacizumab/administración & dosificación , Coroides/patología , Neovascularización Coroidal/diagnóstico , Ranibizumab/administración & dosificación , Factor A de Crecimiento Endotelial Vascular/antagonistas & inhibidores , Agudeza Visual , Inhibidores de la Angiogénesis/administración & dosificación , Estrías Angioides/diagnóstico , Estrías Angioides/tratamiento farmacológico , Coroides/efectos de los fármacos , Neovascularización Coroidal/tratamiento farmacológico , Neovascularización Coroidal/etiología , Angiografía con Fluoresceína/métodos , Estudios de Seguimiento , Fondo de Ojo , Humanos , Inyecciones Intravítreas , Masculino , Persona de Mediana Edad , Estudios Retrospectivos , Factores de Tiempo , Tomografía de Coherencia Óptica/métodos , Resultado del Tratamiento
6.
Chaos ; 27(11): 114302, 2017 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-29195300

RESUMEN

The effect of noise in an excitable semiconductor laser with feedback is studied in the framework of the spatio-temporal representation of long delayed systems. Propagation, noise-induced creation, and destruction of excitable pulses in the pseudo time are observed. The addition of a variable quantity of noise leads to the occurrence of a phenomenon that we term "pseudo-spatial coherence resonance." A phenomenological model well describes the system and allows for a comparison with the experimental observations. A simple Monte Carlo approach is also introduced and permits to explain the features observed in terms of the key dynamical ingredients of the physical system.

7.
Phys Rev Lett ; 112(17): 174103, 2014 May 02.
Artículo en Inglés | MEDLINE | ID: mdl-24836250

RESUMEN

Dynamical systems with complex delayed interactions arise commonly when propagation times are significant, yielding complicated oscillatory instabilities. In this Letter, we introduce a class of systems with multiple, hierarchically long time delays, and using a suitable space-time representation we uncover features otherwise hidden in their temporal dynamics. The behavior in the case of two delays is shown to "encode" two-dimensional spiral defects and defects turbulence. A multiple scale analysis sets the equivalence to a complex Ginzburg-Landau equation, and a novel criterium for the attainment of the long-delay regime is introduced. We also demonstrate this phenomenon for a semiconductor laser with two delayed optical feedbacks.

8.
Phys Rev Lett ; 112(10): 103901, 2014 Mar 14.
Artículo en Inglés | MEDLINE | ID: mdl-24679295

RESUMEN

Localized structures have been observed in many spatially extended systems of either biological, chemical, or physical nature. Here, we study experimentally front pinning and dissipative localized structures in a delayed optical system based on a bistable semiconductor laser with optoelectronic feedback. We observe that many of the concepts known to apply to spatially localized structures also apply in this context, with specificities related to the lack of reversibility symmetry. Numerical simulations based on purely prototypical modeling reproduce very well the experimental findings, which indicates that the results do not depend on the specific physical system under consideration, but are, on the contrary, very generic features of time delayed systems.

9.
Retina ; 34(5): 860-7, 2014 May.
Artículo en Inglés | MEDLINE | ID: mdl-24756034

RESUMEN

PURPOSE: To evaluate the efficacy of intravitreal ranibizumab with a "pro re nata" regimen in the treatment of nonsubfoveal neovascular membranes secondary to age-related macular degeneration. METHODS: Retrospective noncomparative case series. Thirty-one eyes with naive nonsubfoveal neovascularization secondary to age-related macular degeneration were consecutively enrolled and treated with ranibizumab intravitreal injections according to a pro re nata regimen. The follow-up was performed monthly up to 6 months and quarterly up to 2 years (25 patients). Early treatment diabetic retinopathy study best-corrected visual acuity and lesion size analysis with fluorescein angiography were recorded. RESULTS: The mean baseline early treatment diabetic retinopathy study best-corrected visual acuity worsened from 20/40 (0.28 logMAR) at baseline to 20/50 (0.42 logMAR) at 1-year follow-up and 20/60 (0.53 logMAR) at 2-year follow-up. The mean lesions size nearly doubled from baseline at the 2-year follow up (1.19-2.47 mm). Twenty-two patients had one or more recurrences at 1-year follow-up. All 25 patients developed a recurrence at 2 years with 7 cases developing a recurrence by 12 months. Twelve cases progressed to subfoveal lesions by the 24-month visit. CONCLUSION: Other regimens described in the literature might result in a more the satisfactory outcome using more frequent follow-up and more frequent intravitreal injections.


Asunto(s)
Inhibidores de la Angiogénesis/uso terapéutico , Anticuerpos Monoclonales Humanizados/uso terapéutico , Neovascularización Coroidal/tratamiento farmacológico , Fóvea Central , Degeneración Macular Húmeda/tratamiento farmacológico , Anciano , Anciano de 80 o más Años , Inhibidores de la Angiogénesis/administración & dosificación , Anticuerpos Monoclonales Humanizados/administración & dosificación , Neovascularización Coroidal/fisiopatología , Colorantes , Femenino , Angiografía con Fluoresceína , Humanos , Verde de Indocianina , Inyecciones Intravítreas , Masculino , Persona de Mediana Edad , Ranibizumab , Estudios Retrospectivos , Tomografía de Coherencia Óptica , Resultado del Tratamiento , Factor A de Crecimiento Endotelial Vascular/antagonistas & inhibidores , Agudeza Visual/fisiología , Degeneración Macular Húmeda/diagnóstico , Degeneración Macular Húmeda/fisiopatología
10.
PLoS One ; 19(8): e0308569, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-39121177

RESUMEN

PURPOSE: To estimate utility values associated with visual loss using EuroQol (EQ-5D) questionnaire, the impact of low-vision (LV) device use on utilities and the contribution of Instrumental Activities of Daily Living (IADL) score in patients attending vision rehabilitation (VR) services enrolled in the Italian Device & Aids Register (D.A.Re). METHODS: This is a multicenter, prospective, cross-sectional study. D.A.Re. collects general and clinical information, vision-specific variables, use of electronic devices and quality of life questionnaires. RESULTS: A total of 442 patients (75.0±16.6 years, 275 female) were included, 88 (19.9%) used specialised electronic LV devices, and 116 (26.2%) used smartphones and tablets. Users of smartphones and tablets were younger than non-users (67.5 vs. 77.6 years, p<0.001), but overall, their age ranged between 20 and 93. Stronger associations were found between vision-specific variables and IADL score compared to EQ-5D score. In multivariable age-adjusted models, the utility value of using smartphones and tablets on EQ-5D score was 0.12 (p<0.01), slightly larger than that of 1.0 logMAR difference (-0.09, p<0.01) or visual field damage within 10° of fixation (-0.10, p<0.01). Use of portable low-vision electronic devices and being employed or student (vs. retired) was also associated with better utility values (0.12 and 0.15, respectively, p<0.05). CONCLUSIONS: Visual loss is associated with loss of utilities in Italian patients attending VR services, whereas special-purpose electronic aids, and smartphone and tablet use are associated with better utility values. We found that IADL may be more sensitive to visual loss than EQ-5D and could be a valid health-related quality of life outcome in trials on VR.


Asunto(s)
Actividades Cotidianas , Calidad de Vida , Sistema de Registros , Teléfono Inteligente , Baja Visión , Humanos , Femenino , Masculino , Italia , Anciano , Persona de Mediana Edad , Baja Visión/rehabilitación , Estudios Transversales , Anciano de 80 o más Años , Estudios Prospectivos , Adulto , Encuestas y Cuestionarios , Adulto Joven
11.
Cochrane Database Syst Rev ; (10): CD003303, 2013 Oct 23.
Artículo en Inglés | MEDLINE | ID: mdl-24154864

RESUMEN

BACKGROUND: The purpose of low-vision rehabilitation is to allow people to resume or to continue to perform daily living tasks, with reading being one of the most important. This is achieved by providing appropriate optical devices and special training in the use of residual-vision and low-vision aids, which range from simple optical magnifiers to high-magnification video magnifiers. OBJECTIVES: To assess the effects of reading aids for adults with low vision. SEARCH METHODS: We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (The Cochrane Library 2013, Issue 1), Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid OLDMEDLINE, (January 1950 to January 2013), EMBASE (January 1980 to January 2013), Latin American and Caribbean Literature on Health Sciences (LILACS) (January 1982 to January 2013), OpenGrey (System for Information on Grey Literature in Europe) (www.opengrey.eu/), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrials.gov/) and the WHO International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). We did not use any date or language restrictions in the electronic searches for trials. We last searched the electronic databases on 31 January 2013. We searched the reference lists of relevant articles and used the Science Citation Index to find articles that cited the included studies and contacted investigators and manufacturers of low-vision aids. We handsearched the British Journal of Visual Impairment from 1983 to 1999 and the Journal of Visual Impairment and Blindness from 1976 to 1991. SELECTION CRITERIA: This review includes randomised and quasi-randomised trials in which any device or aid used for reading had been compared to another device or aid in people aged 16 or over with low vision as defined by the study investigators. DATA COLLECTION AND ANALYSIS: At least two authors independently assessed trial quality and extracted data. MAIN RESULTS: We included nine small studies with a cross-over-like design (181 people overall) and one study with three parallel arms (243 participants) in the review. All studies reported the primary outcome, results for reading speed.Two studies including 92 participants found moderate- or low-quality evidence suggesting that reading speed is higher with stand-mounted electronic devices or electronic devices with the camera mounted in a 'mouse' than with optical magnifiers, which in these trials were generally stand-mounted or, less frequently, hand-held magnifiers or microscopic lenses. In another study of 20 participants there was moderate-quality evidence that optical devices are better than head-mounted electronic devices (four types).There was low-quality evidence from three studies (93 participants) that reading using head-mounted electronic devices is slower than with stand-based electronic devices. The technology of electronic devices may have changed and improved since these studies were conducted.One study suggested no difference between a diffractive spectacle-mounted magnifier and either refractive (15 participants) or aplanatic (15 participants) magnifiers.One study of 10 people suggested that several overlay coloured filters were no better and possibly worse than a clear filter.A parallel-arm study including 243 participants with age-related macular degeneration found that custom or standard prism spectacles were no different from conventional reading spectacles, although the data did not allow precise estimates of performance to be made. AUTHORS' CONCLUSIONS: There is insufficient evidence on the effect of different types of low-vision aids on reading performance. It would be necessary to investigate which patient characteristics predict performance with different devices, including costly electronic devices. Better-quality research should also focus on assessing sustained long-term use of each device. Authors of studies testing several devices on the same person should consider design and reporting issues related to their sequential presentation and to the cross-over-like study design.


Asunto(s)
Dispositivos Ópticos/normas , Lectura , Auxiliares Sensoriales , Baja Visión/rehabilitación , Personas con Daño Visual/rehabilitación , Adulto , Anteojos , Humanos , Lentes , Degeneración Macular/complicaciones , Ensayos Clínicos Controlados Aleatorios como Asunto , Agudeza Visual
12.
J Refract Surg ; 28(8): 562-6, 2012 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-22785060

RESUMEN

PURPOSE: To compare minimum corneal pachymetry assessment using three measurement methods in eyes before and after corneal collagen cross-linking (CXL) for keratoconus. METHODS: Fifty patients (54 eyes) who underwent CXL for keratoconus were evaluated with the Visante (Carl Zeiss Meditec), Pentacam (Oculus Optikgeräte GmbH), and ultrasound pachymetry (USP) (Optikon Pacline) to assess corneal thickness at baseline and 1, 3, 6, and 12 months after treatment. RESULTS: Using USP, mean thickness was 456 µm at baseline, decreased by approximately 8 µm at 1 month, and then recovered to initial values. The mean difference between Visante and USP was statistically significant, but not clinically significant, and was similar at baseline and after CXL (-1 to -2 µm, P<.05 except for 12 months). Pentacam had similar readings at baseline (-2 µm vs USP), but lower corneal thickness after CXL (-12 to -20 µm throughout follow-up, P<.001). The width of the Bland-Altman 95% agreement interval of Visante and Pentacam with USP was approximately 5 µm and 15 µm, respectively. CONCLUSIONS: Visante pachymetry shows better agreement with USP compared to Pentacam after CXL, which may be due to the inhomogeneous reflectivity of the postoperative cross-linked cornea and possibly altered refractive index and acoustic impedance that may influence the observed differences among techniques.


Asunto(s)
Córnea/patología , Reactivos de Enlaces Cruzados/uso terapéutico , Técnicas de Diagnóstico Oftalmológico , Queratocono/diagnóstico , Adulto , Biometría/métodos , Colágeno/metabolismo , Sustancia Propia/metabolismo , Topografía de la Córnea , Femenino , Humanos , Queratocono/tratamiento farmacológico , Queratocono/metabolismo , Masculino , Fármacos Fotosensibilizantes/uso terapéutico , Riboflavina/uso terapéutico , Tomografía de Coherencia Óptica , Ultrasonografía , Rayos Ultravioleta
13.
Eur J Ophthalmol ; 31(5): 2556-2562, 2021 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-33008267

RESUMEN

PURPOSE: To investigate saccadic movements in subjects with eccentric fixation due to a deep central scotoma in Stargardt disease (STGD). METHODS: We studied 10 patients with STGD and 10 healthy subjects (control group). Saccadic movements of all the 20 subjects were assessed by using the eye tracker technique Tobii Glasses Pro 2. Standard measurements of reading ability (MNREAD charts), visual acuity (ETDRS charts), contrast sensitivity (Pelli-Robson charts), reading contrast threshold and speed (REX charts), retinal sensitivity and stability and localization of the fixation (MP1 fundus perimetry) were obtained in all subjects. RESULTS: The saccadic movements time was significantly slower in STGD than in healthy subjects (699 ± 193 ms vs 299 ± 40 ms, p < 0.001). When STGD patients moved fixation to the target localized in retinal scotomatous areas, the movement was significantly slower compared to non scotomatous areas in the retina (1103 ± 798 ms vs 524 ± 187 ms, p = 0.039). There was a trend toward a correlation between slow saccadic movements in STGD subjects and the reading performance indices, although statistical significance was not achieved. CONCLUSION: Ocular saccades guided by eccentric fixation in STGD patients are significantly slower than in the control group, especially when the target corresponds to retinal areas with a deep scotoma. These results can explain the worse reading performance in STGD subjects, in particular when a non-viewing area on the right part of the text is present.


Asunto(s)
Trastornos de la Visión , Pruebas del Campo Visual , Fijación Ocular , Humanos , Lectura , Escotoma/diagnóstico , Escotoma/etiología , Enfermedad de Stargardt , Agudeza Visual
14.
Phys Rev Lett ; 104(19): 194101, 2010 May 14.
Artículo en Inglés | MEDLINE | ID: mdl-20866966

RESUMEN

We characterize the response of a chaotic system by investigating ensembles of, rather than single, trajectories. Time-periodic stimulations are experimentally and numerically investigated. This approach allows detecting and characterizing a broad class of coherent phenomena that go beyond generalized and phase synchronization. In particular, we find that a large average response is not necessarily related to the presence of standard forms of synchronization. Moreover, we study the stability of the response, by introducing an effective method to determine the largest nonzero eigenvalue -γ1 of the corresponding Liouville-type operator, without the need of directly simulating it. The exponent γ1 is a dynamical invariant, which complements the standard characterization provided by the Lyapunov exponents.

15.
Eur J Ophthalmol ; 20(2): 389-96, 2010.
Artículo en Inglés | MEDLINE | ID: mdl-19882511

RESUMEN

PURPOSE: To investigate the reliability of the Reading Explorer (REX) charts and to assess the impact of text contrast reduction (1.5 cycle/degree) on reading speed in subjects with normal and low vision. METHODS: Standard visual acuity (ETDRS charts), reading speed (MNread charts), and contrast sensitivity (Pelli-Robson charts) measurements were obtained in 3 groups of subjects stratified by visual acuity level in the better eye from 0.0 to 1.0 logMAR, with intermediate cutoffs at 0.3 and 0.6 logMAR. Measurements of reading speed for decreasing levels of text contrast were obtained with the REX charts using a 1.5 cycle/degree text. RESULTS: Since in many patients with lower vision a plateau of maximum reading speed across different levels of text contrast was not found, reliability indexes were computed for average reading speed and reading contrast threshold. In the group with lower visual acuity, 95% limits of agreement were +/-0.134 log word/minute and +/-0.175 log contrast sensitivity, suggesting good reliability. The proportion of subjects with a 20% loss of reading speed from 90% to 45% text contrast was estimated to be 1/3 at 0.6 logMAR visual acuity level and 2/3 at 1.0 logMAR. CONCLUSIONS: The adverse effect of decreased text contrast, which may be found in ordinary reading material, on the reading performance of subjects with advanced and initial low vision is probably underestimated. The REX test proved to be a reliable investigation tool for this phenomenon.


Asunto(s)
Sensibilidad de Contraste/fisiología , Lectura , Pruebas de Visión/métodos , Baja Visión/fisiopatología , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Humanos , Persona de Mediana Edad , Curva ROC , Reproducibilidad de los Resultados , Baja Visión/diagnóstico , Adulto Joven
16.
Phys Rev E ; 102(5-1): 052217, 2020 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-33327079

RESUMEN

Dynamical systems with long-delay feedback can exhibit complicated temporal phenomena, which once reorganized in a two-dimensional space are reminiscent of spatiotemporal behavior. In this framework, a normal forms description has been developed to reproduce the dynamics, and the opportunity to treat the corresponding variables as true space and time has since been established. However, recently, an alternative approach has been proposed [F. Marino and G. Giacomelli, Phys. Rev. E 98, 060201(R) (2018)2470-004510.1103/PhysRevE.98.060201] with a different interpretation of the variables involved, which better takes into account their physical character and allows for an easier determination of the normal forms. In this paper, we extend such idea and apply it to a number of paradigmatic examples, paving the way to a rethinking of the concept of spatiotemporal representation of long-delayed systems.

17.
Photodiagnosis Photodyn Ther ; 31: 101960, 2020 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-32818639

RESUMEN

BACKGROUND: Photodynamic therapy has revolutionised the treatment of circumscribed choroidal hemangiomas. The aim of this report is to report the long-term follow-up of patients affected by circumscribed choroidal hemangioma treated using photodynamic therapy. MATERIALS AND METHODS: We retrospectively reviewed patients affected by circumscribed choroidal hemangioma examined at the Retinal Medical Department at the Eye Clinic in Florence. We studied circumscribed choroidal hemangiomas treated using photodynamic therapy with at least 1 follow-up examination. Verteporfin was administered intravenously for 10 min (6 mg/m2 body surface area). After infusion (5 min), a 689 nm laser was applied with a light dose of 50 J/cm2. RESULTS: Ten eyes of 10 patients with circumscribed choroidal hemangioma who underwent Photodynamic therapy were included in our series (2 females and 8 males; average age at diagnosis 47.8 ± 9.3 yrs.; age range: 27-56 years). Five patients (5/10; 50 %) received only the photodynamic treatment whereas 5 patients (5/10; 50 %) also received other treatments (laser photocoagulation, intravitreal injection). On average, the patients received 2 photodynamic treatments (range 1-4). Four patients (4/10, 40 %) had a > 5-year follow-up; (average 4.5 ± 3.7 yrs. range 6 months - 10 years). In 2 patients we identified the "double layer sign" at the optical coherence tomography examination on circumscribed choroidal hemangioma. CONCLUSIONS: In our series, photodynamic therapy was a safe and effective treatment for circumscribed choroidal hemangioma during long-term follow-up. The double layer sign, which can be detected in several choroidal pathologies, suggests common pathogenetic mechanisms for circumscribed choroidal hemangiomas and central serous chorioretinopathy/polypoidal choroidopathy spectrum disease.


Asunto(s)
Neoplasias de la Coroides , Hemangioma , Fotoquimioterapia , Adulto , Neoplasias de la Coroides/tratamiento farmacológico , Femenino , Angiografía con Fluoresceína , Estudios de Seguimiento , Hemangioma/tratamiento farmacológico , Humanos , Masculino , Persona de Mediana Edad , Fotoquimioterapia/métodos , Fármacos Fotosensibilizantes/uso terapéutico , Estudios Retrospectivos , Resultado del Tratamiento , Agudeza Visual
18.
Invest Ophthalmol Vis Sci ; 61(6): 40, 2020 Jun 03.
Artículo en Inglés | MEDLINE | ID: mdl-38755787

RESUMEN

Purpose: Visual acuity (VA) and contrast sensitivity (CS) characterize different aspects of visual function. Whereas VA is a standard test in routine eye exams and clinical trials, CS is often not included. We investigated the pathology-specific dissociation between VA and CS by quantifying and comparing the relationship between these two measures in common ocular pathologies. Methods: VA and CS data were assembled from 1113 subjects, including groups with cataract (n = 450), age-related macular degeneration (AMD; n = 232), glaucoma (n = 100), retinitis pigmentosa (RP; n = 87), and normal ocular health (n = 244). VA and CS were measured by the Early Treatment Diabetic Retinopathy Study chart and Pelli-Robson chart, respectively. Results: Even when VA was relatively normal (<0.3 logMAR), the four ocular pathology groups showed quantitatively different mean CS deficits relative to normal controls, ranging from -0.01 log units for cataract to 0.23 log units for RP. When the entire range of VA was considered, the corresponding deficits in CS were noticeably different across these four groups, being least for cataract and progressively more severe for glaucoma, AMD, and RP. For every 1.0 logMAR loss of VA, the corresponding deficit in CS ranged from 0.22 logCS for cataract to 0.97 logCS for RP. Conclusions: The quantitative relationship between VA and CS depends on the ocular pathology. CS appears to provide valuable complementary information to VA in the early detection of eye disease and when evaluating visual impairment.

19.
Eur J Ophthalmol ; 30(5): 1014-1018, 2020 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-31113297

RESUMEN

PURPOSE: The Veterans Affairs Low-Vision Visual Functioning Questionnaire-48 is among the most validated tools to collect patient-reported outcomes in a low-vision population. We have aimed to conduct a pilot validation of the Italian version of the Veterans Affairs Low-Vision Visual Functioning Questionnaire-48. METHODS: The Veterans Affairs Low-Vision Visual Functioning Questionnaire-48 was translated using a standardized procedure and then administered to consecutive low-vision patients attending rehabilitation services in three centers. Patients were interviewed by a trained psychologist regarding the individual items of the tool. RESULTS: We included 131 patients with a mean visual acuity of 0.91 logMAR (standard deviation: 0.42 logMAR), mostly affected by age-related macular degeneration. The Veterans Affairs Low-Vision Visual Functioning Questionnaire-48 showed high internal consistency (Cronbach's alpha: 0.98) and good item-test and item-rest correlation (median: 0.73 and 0.71, respectively). Both the overall score and the subscale (reading, visual motor, mobility and visual information) scores significantly correlated with visual acuity, reading acuity and speed. Reading speed achieved the best absolute correlation with the Veterans Affairs Low-Vision Visual Functioning Questionnaire-48 scores (Spearman r: 0.39-0.49). CONCLUSION: The Italian version of the Veterans Affairs Low-Vision Visual Functioning Questionnaire-48 is a valid tool to assess patients attending low-vision services. Revising a few items may further improve the tool.


Asunto(s)
Actividades Cotidianas/psicología , Lenguaje , Perfil de Impacto de Enfermedad , Encuestas y Cuestionarios , Baja Visión/psicología , Anciano , Femenino , Humanos , Italia , Masculino , Persona de Mediana Edad , Proyectos Piloto , Calidad de Vida/psicología , Estados Unidos , United States Department of Veterans Affairs , Baja Visión/rehabilitación , Agudeza Visual/fisiología
20.
Ophthalmologica ; 223(1): 24-7, 2009.
Artículo en Inglés | MEDLINE | ID: mdl-18849633

RESUMEN

BACKGROUND: Intravitreal (IV) bevacizumab (Avastin(R), Roche), initially used for the off-label treatment of neovascular age-related macular degeneration (AMD), has extended itself to treat various ocular pathologies such as choroidal neovascularization not associated to AMD. METHODS: IV bevacizumab 1,25 mg (Avastin) was used in the treatment of choroidal neovascularization (CNV) in 6 eyes of 5 patients with angioid streaks. All cases had a history of photodynamic treatment (PDT) or laser treatment and all showed progressive worsening despite the use of these therapies. RESULTS: After injection patients were followed up at nearly 2-month intervals. IV Avastin was repeated in case of recurrence. Three eyes were treated combining PDT and IV Avastin. Cases were followed up for 7-14 months. All patients needed more IV injections. Five out of 6 eyes showed an improvement of BCVA and a slight reduction of leakage and size with FA. CONCLUSION: This small series suggests that IV Avastin might be useful in the treatment of CNV due to AS.


Asunto(s)
Inhibidores de la Angiogénesis/administración & dosificación , Estrías Angioides/complicaciones , Anticuerpos Monoclonales/administración & dosificación , Neovascularización Coroidal/tratamiento farmacológico , Neovascularización Coroidal/etiología , Anciano , Anticuerpos Monoclonales Humanizados , Bevacizumab , Neovascularización Coroidal/complicaciones , Neovascularización Coroidal/fisiopatología , Quimioterapia Combinada , Femenino , Angiografía con Fluoresceína , Estudios de Seguimiento , Hemorragia/diagnóstico , Hemorragia/etiología , Humanos , Inyecciones , Masculino , Registros Médicos , Persona de Mediana Edad , Fotoquimioterapia , Recurrencia , Retratamiento , Agudeza Visual/efectos de los fármacos , Cuerpo Vítreo
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