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1.
Nat Commun ; 10(1): 5672, 2019 12 12.
Artigo em Inglês | MEDLINE | ID: mdl-31831746

RESUMO

Constructing colloidal particles into functional nanostructures, materials, and devices is a promising yet challenging direction. Many optical techniques have been developed to trap, manipulate, assemble, and print colloidal particles from aqueous solutions into desired configurations on solid substrates. However, these techniques operated in liquid environments generally suffer from pattern collapses, Brownian motion, and challenges that come with reconfigurable assembly. Here, we develop an all-optical technique, termed optothermally-gated photon nudging (OPN), for the versatile manipulation and dynamic patterning of a variety of colloidal particles on a solid substrate at nanoscale accuracy. OPN takes advantage of a thin surfactant layer to optothermally modulate the particle-substrate interaction, which enables the manipulation of colloidal particles on solid substrates with optical scattering force. Along with in situ optical spectroscopy, our non-invasive and contactless nanomanipulation technique will find various applications in nanofabrication, nanophotonics, nanoelectronics, and colloidal sciences.


Assuntos
Coloides/química , Nanoestruturas/química , Óptica e Fotônica/métodos , Fótons , Fenômenos Biofísicos , Movimento (Física) , Tamanho da Partícula , Tensoativos/química , Temperatura Ambiente
2.
Phys Rev Lett ; 123(16): 163901, 2019 Oct 18.
Artigo em Inglês | MEDLINE | ID: mdl-31702361

RESUMO

When the feature size of photonic structures becomes comparable or even smaller than the wavelength of light, the fabrication imperfections inevitably introduce disorder that may eliminate many functionalities of subwavelength photonic devices. Here we suggest a novel concept to achieve a robust band gap which can endure disorder beyond 30% as a result of the transition from photonic crystals to Mie-resonant metamaterials. By utilizing Mie-resonant metamaterials with high refractive index, we demonstrate photonic waveguides and cavities with strong robustness to position disorder, thus providing a novel approach to the band-gap-based nanophotonic devices with new properties and functionalities.


Assuntos
Modelos Teóricos , Óptica e Fotônica/métodos , Fótons
3.
Sensors (Basel) ; 19(17)2019 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-31480393

RESUMO

The past decades have witnessed the rapid development in soft, stretchable, and biocompatible devices for applications in biomedical monitoring, personal healthcare, and human-machine interfaces. In particular, the design of soft devices in optics has attracted tremendous interests attributed to their distinct advantages such as inherent electrical safety, high stability in long-term operation, potential to be miniaturized, and free of electromagnetic interferences. As the alternatives to conventional rigid optical waveguides, considerable efforts have been made to develop light-guiding devices by using various transparent and elastic polymers, which offer desired physiomechanical properties and enable wearable/implantable applications in optical sensing, diagnostics, and therapy. Here, we review recent progress in soft and stretchable optical waveguides and sensors, including advanced structural design, fabrication strategies, and functionalities. Furthermore, the potential applications of those optical devices for various wearable and biomedical applications are discussed. It is expected that the newly emerged soft and stretchable optical technologies will provide a safe and reliable alternative to next-generation, smart wearables and healthcare devices.


Assuntos
Sistemas Homem-Máquina , Monitorização Fisiológica/instrumentação , Óptica e Fotônica/instrumentação , Polímeros/química , Dispositivos Eletrônicos Vestíveis , Materiais Biocompatíveis , Humanos , Hidrogéis/química , Monitorização Fisiológica/métodos , Óptica e Fotônica/métodos , Próteses e Implantes , Robótica
4.
Sensors (Basel) ; 19(17)2019 Aug 23.
Artigo em Inglês | MEDLINE | ID: mdl-31450817

RESUMO

Waveguide-based photonic sensors provide a unique combination of high sensitivity, compact size and label-free, multiplexed operation. Interferometric configurations furthermore enable a simple, fixed-wavelength read-out making them particularly suitable for low-cost diagnostic and monitoring devices. Their limit of detection, i.e., the lowest analyte concentration that can be reliably observed, mainly depends on the sensors response to small refractive index changes, and the noise in the read-out system. While enhancements in the sensors response have been extensively studied, noise optimization has received much less attention. Here we show that order-of-magnitude enhancements in the limit of detection can be achieved through systematic noise reduction, and demonstrate a limit of detection of ∼ 10 - 8 RIU with a silicon nitride sensor operating at telecom wavelengths.


Assuntos
Técnicas Biossensoriais , Óptica e Fotônica/métodos , Compostos de Silício/isolamento & purificação , Interferometria , Limite de Detecção , Compostos de Silício/química
5.
Molecules ; 24(13)2019 Jul 02.
Artigo em Inglês | MEDLINE | ID: mdl-31269660

RESUMO

Pesticides vary in the level of poisonousness, while a conventional rapid test card only provides a general "absence or not" solution, which cannot identify the various genera of pesticides. In order to solve this problem, we proposed a seven-layer paper-based microfluidic chip, integrating the enzyme acetylcholinesterase (AChE) and chromogenic reaction. It enables on-chip pesticide identification via a reflected light intensity spectrum in time-sequence according to the different reaction efficiencies of pesticide molecules and assures the optimum temperature for enzyme activity. After pretreatment of figures of reflected light intensity during the 15 min period, the figures mainly focused on the reflected light variations aroused by the enzyme inhibition assay, and thus, the linear discriminant analysis showed satisfying discrimination of imidacloprid (Y = -1.6525X - 139.7500), phorate (Y = -3.9689X - 483.0526), and avermectin (Y = -2.3617X - 28.3082). The correlation coefficients for these linearity curves were 0.9635, 0.8093, and 0.9094, respectively, with a 95% limit of agreement. Then, the avermectin class chemicals and real-world samples (i.e., lettuce and rice) were tested, which all showed feasible graphic results to distinguish all the chemicals. Therefore, it is feasible to distinguish the three tested kinds of pesticides by the changes in the reflected light spectrum in each min (15 min) via the proposed chip with a high level of automation and integration.


Assuntos
Inibidores Enzimáticos/análise , Dispositivos Lab-On-A-Chip , Óptica e Fotônica/métodos , Papel , Resíduos de Praguicidas/análise , Análise por Conglomerados , Ivermectina/análogos & derivados , Ivermectina/análise , Ivermectina/química , Neonicotinoides/análise , Neonicotinoides/química , Nitrocompostos/análise , Nitrocompostos/química , Forato/análise , Forato/química , Fatores de Tempo
6.
Biomed Res Int ; 2019: 6425040, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31346522

RESUMO

The number of presbyopia correcting intraocular lenses (IOLs) is increasing and new technologies are constantly emerging with the aim of correcting the loss of accommodation after cataract surgery. Various optical designs have been proposed to implement multifocality or an extended depth of focus (EDOF). Depending on the optical principle of an implanted lens, the visual performance often is deteriorated by superposition of individual image planes and halos of varying intensity. This experimental study presents a concept to visualize the light fields and especially the halos of mono- and multifocal IOLs using the well known alcoholic beverage "ouzo" in order to obtain qualitative data on the imaging characteristics. We conclude that ouzo is a useful, cost effective, and nonpolluting medium for beam visualization and an alternative to fluorescein or milk, which could find an application for educational purposes.


Assuntos
Acomodação Ocular/fisiologia , Extração de Catarata/métodos , Catarata/terapia , Lentes Intraoculares Multifocais , Catarata/fisiopatologia , Humanos , Luz , Óptica e Fotônica/métodos , Visão Ocular/fisiologia , Acuidade Visual/fisiologia
7.
Semin Ophthalmol ; 34(4): 205-210, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31188043

RESUMO

Purpose: Corneal opacity is a common clinical problem that directly impedes the cornea's function of light transmission. Despite this, there are no standard means of quantifying opacity. The purpose of this review is to summarize the reported options both clinicians and researchers have for objectively assessing corneal opacity. Methods: Review of the peer-reviewed literature reporting methods for assessing clinical opacity and transparency in both the research and clinic setting. Conclusion: Although a number of techniques for assessing corneal opacity have been reported in the literature, none have been widely adopted, highlighting the fact that there is still a need for an accessible, objective and easy to use method for quantifying corneal opacity.


Assuntos
Opacidade da Córnea/diagnóstico , Técnicas de Diagnóstico Oftalmológico , Óptica e Fotônica/métodos , Humanos
8.
Semin Ophthalmol ; 34(4): 189-197, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31188056

RESUMO

Retinal imaging is a fundamental tool for clinical and research efforts in the evaluation and management of diabetic retinopathy. Adaptive optics (AO) is an imaging technique that enables correction of over 90% of the optical aberrations of an individual eye induced primarily by the tear film, cornea and lens. The two major tasks of any AO system are to measure the optical imperfections of the eye and to then compensate for these aberrations to generate a corrected wavefront of reflected light from the eye. AO scanning laser ophthalmoscopy (AOSLO) provides a theoretical lateral resolution limit of 1.4 µm, allowing the study of microscopic features of the retinal vascular and neural tissue. AOSLO studies have revealed irregularities of the photoreceptor mosaic, vascular loss, and details of vascular lesions in diabetic eyes that may provide new insight into development, regression, and response to therapy of diabetic eye disease.


Assuntos
Retinopatia Diabética/diagnóstico por imagem , Oftalmoscopia/métodos , Óptica e Fotônica/métodos , Angiofluoresceinografia , Humanos , Tomografia de Coerência Óptica/métodos
9.
Ophthalmic Physiol Opt ; 39(4): 232-244, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-31172533

RESUMO

PURPOSE: This report uses the principles of geometrical optics to compute the optical point-spread function (PSF) from the wavefront error function. METHOD: Step 1 uses Prentice's rule to determine the spatial form of the PSF established by tracing a field of rays from the eye's exit pupil to the retina. Ray vergence is related to the slope of the wavefront error function, which enables the mapping of light rays to produce a retinal 'spot diagram'. Step 2 completes the PSF by assigning an irradiance value to each ray in the spot diagram. RESULTS AND CONCLUSIONS: Spot irradiance is inversely proportional to the Gaussian curvature (i.e. the product of principal curvatures) of each local region of wavefront error surface centered on the corresponding ray. The Gaussian curvature, in turn, may be computed as the determinant of the vergence error matrix associated with each point on the wavefront error surface. Elements of the vergence error matrix consist of sums and differences of the local power vector components M, J0 and J45 . This method is shown to be equivalent to published derivations of the geometric PSF using the Jacobian of the ray mapping function and equivalent also to the Hessian of the wavefront error function. Examples are presented for the familiar cases of spherical and astigmatic blur as well as for higher order aberrations and the formation of caustics in the retinal image.


Assuntos
Astigmatismo/fisiopatologia , Aberrações de Frente de Onda da Córnea/fisiopatologia , Óptica e Fotônica/métodos , Transtornos da Visão/fisiopatologia , Humanos , Matemática , Refração Ocular/fisiologia
10.
Opt Express ; 27(12): 17102-17111, 2019 Jun 10.
Artigo em Inglês | MEDLINE | ID: mdl-31252927

RESUMO

We demonstrate a photonic integrated Mach-Zehnder interferometric sensor, utilizing a plasmonic stripe waveguide in the sensing branch and a photonic variable optical attenuator and a phase shifter in the reference arm to optimize the interferometer operation. The plasmonic sensor is used to detect changes in the refractive index of the surrounding medium exploiting the accumulated phase change of the propagating Surface-Plasmon-Polariton (SPP) mode that is fully exposed in an aqueous buffer solution. The variable optical attenuation stage is incorporated in the reference Si3N4 branch, as the means to counter-balance the optical losses introduced by the plasmonic branch and optimize interference at the sensor output. Bulk sensitivity values of 1930 nm/RIU were experimentally measured for a Mach Zehnder Interferometer (MZI) with a Free Spectral Range of 24.8 nm, along with extinction ratio of more than 35 dB, demonstrating the functional benefits of the co-integration of plasmonic and photonic waveguides.


Assuntos
Técnicas Biossensoriais/métodos , Interferometria/métodos , Óptica e Fotônica/métodos , Compostos de Silício/química , Eletricidade , Refratometria
11.
Adv Mater ; 31(30): e1806739, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31094032

RESUMO

Disposable sensors are low-cost and easy-to-use sensing devices intended for short-term or rapid single-point measurements. The growing demand for fast, accessible, and reliable information in a vastly connected world makes disposable sensors increasingly important. The areas of application for such devices are numerous, ranging from pharmaceutical, agricultural, environmental, forensic, and food sciences to wearables and clinical diagnostics, especially in resource-limited settings. The capabilities of disposable sensors can extend beyond measuring traditional physical quantities (for example, temperature or pressure); they can provide critical chemical and biological information (chemo- and biosensors) that can be digitized and made available to users and centralized/decentralized facilities for data storage, remotely. These features could pave the way for new classes of low-cost systems for health, food, and environmental monitoring that can democratize sensing across the globe. Here, a brief insight into the materials and basics of sensors (methods of transduction, molecular recognition, and amplification) is provided followed by a comprehensive and critical overview of the disposable sensors currently used for medical diagnostics, food, and environmental analysis. Finally, views on how the field of disposable sensing devices will continue its evolution are discussed, including the future trends, challenges, and opportunities.


Assuntos
Técnicas Biossensoriais/instrumentação , Técnicas e Procedimentos Diagnósticos/instrumentação , Equipamentos Descartáveis , Monitoramento Ambiental/instrumentação , Análise de Alimentos/instrumentação , Animais , Técnicas Eletroquímicas/métodos , Desenho de Equipamento , Vidro/química , Humanos , Membranas Artificiais , Nanoestruturas/química , Óptica e Fotônica/métodos , Polímeros/química
12.
Ultramicroscopy ; 202: 76-86, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-31003162

RESUMO

Multilayer normal-incidence mirrors allow the numerical aperture (NA=0.3-0.5) of a projection lens to be significantly increased in the spectral ranges of the water (λ = 2.3-4.4 nm) and carbon (λ = 4.4-7 nm) windows, in comparison with the Fresnel zone plates. The low depth of focus of high-aperture optics (tens of nm) makes it possible to use z-tomography to reconstruct the structure of samples in soft X-ray microscopy. The presence of strong absorption prevents the direct use of a powerful deconvolution apparatus developed for fluorescence optical microscopy to improve the clarity of the image. In this article, the "intensity restoration algorithm" is proposed that takes into account the absorption effect before standard deconvolution. For an imagine lens with NA = 0.3 and a working wavelength of 3.37 nm, the results of simulating an image of a protein cell and its deconvolutionary processing are presented, before and after applying the proposed method. After its application, the deconvolution efficiency is significantly increased. A "full-period" resolution of 40 nm was obtained for the image of a simulated protein cell.


Assuntos
Microscopia de Fluorescência/métodos , Tomografia Computadorizada por Raios X/métodos , Algoritmos , Desenho de Equipamento/métodos , Processamento de Imagem Assistida por Computador/métodos , Lentes , Óptica e Fotônica/métodos , Raios X
13.
Methods Cell Biol ; 151: 487-517, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30948028

RESUMO

Sperm from sea urchins are attracted by chemical cues released by the egg-a mechanism called chemotaxis. We describe here the signaling pathway and molecular components endowing sperm with single-molecule sensitivity. Chemotactic signaling and behavioral responses occur on a timescale of a few milliseconds to seconds. We describe the techniques and chemical tools used to resolve the signaling events in time. The techniques include rapid-mixing devices, rapid stroboscopic microscopy, and photolysis of caged second messengers and chemoattractants.


Assuntos
Óptica e Fotônica/métodos , Motilidade Espermática/genética , Espermatozoides/crescimento & desenvolvimento , Estroboscopia/métodos , Animais , Fatores Quimiotáticos/química , Cinética , Masculino , Ouriços-do-Mar/crescimento & desenvolvimento , Espermatozoides/ultraestrutura
14.
Ophthalmic Physiol Opt ; 39(3): 141-147, 2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-30994200

RESUMO

PURPOSE: Screening for uncorrected hyperopia in school children is important given its association with poorer visual function and academic performance. However, standard distance visual acuity screening may not detect low to moderate hyperopia. The plus lens test is used to screen for hyperopia in many school screening protocols, but has not been well validated. The current study investigated the effectiveness of the plus lens test to identify hyperopia in school children. METHODS: Participants included Grade 2 school children. Monocular distance visual acuity (logMAR letter chart) was measured unaided, and then through a +1.50D lens, known as the plus lens test. Cycloplegic refraction was undertaken to classify moderate hyperopia (≥+2.00D). Sensitivity, specificity, positive predictive values (PPV) and negative predictive values (NPV) were calculated for commonly used cut-offs for the plus lens test: 6/6, 6/9 and less than two lines difference between unaided acuity and acuity through the plus lens test. RESULTS: The sample included 59 children (mean age 7.2 ± 0.4 years). Fourteen (24%) children were classified as having uncorrected hyperopia. The sensitivity and specificity of the +1.50 plus lens test for identifying hyperopia were 0% and 98% respectively for a 6/6 cut-off, 29% and 91% for 6/9 cut-off, and 50% and 76% for a <2 line reduction between unaided acuity and acuity through the plus lens test. Receiver Operating Curve (ROC) analysis revealed area under curves of 0.69 based on acuity through the plus lens test, and 0.65 for a reduction in acuity through the plus lens test. CONCLUSIONS: The plus lens test has low sensitivity for detecting uncorrected hyperopia using traditional cut-offs of 6/9 or better. This raises questions about the role of the plus lens test in school screening batteries.


Assuntos
Hiperopia/diagnóstico , Lentes , Óptica e Fotônica/métodos , Refração Ocular/fisiologia , Seleção Visual/métodos , Acuidade Visual/fisiologia , Criança , Feminino , Humanos , Masculino
15.
Nano Lett ; 19(4): 2627-2633, 2019 04 10.
Artigo em Inglês | MEDLINE | ID: mdl-30884236

RESUMO

The biophotonic nanostructures of Morpho butterfly wing display iridescent colors through the combined effect of light diffraction and interference. These nanostructures have attracted wide attention due to their high optical sensitivity and deformable material properties and have been applied to various infrared (IR), volatile organic compound (VOC), and pH sensors. This work explores the application of such biophotonic nanostructures of butterfly wing for acoustic detection and voice recognition. The pressure variation of the acoustic waves induces the vibration of butterfly wing diaphragm, resulting in the periodic change of reflectance. The integrated butterfly wing-based acoustic sensor shows high fidelity in replicating the original acoustic signals. The sensor also demonstrates promise in distinguishing human voices, which provides an alternative approach for voice recognition.


Assuntos
Técnicas Biossensoriais/métodos , Borboletas/fisiologia , Nanoestruturas/química , Asas de Animais/fisiologia , Acústica/instrumentação , Animais , Humanos , Óptica e Fotônica/instrumentação , Óptica e Fotônica/métodos , Vibração , Vocalização Animal
16.
Biosensors (Basel) ; 9(1)2019 Mar 03.
Artigo em Inglês | MEDLINE | ID: mdl-30832416

RESUMO

Biomarkers detection at an ultra-low concentration in biofluids (blood, serum, saliva, etc.) is a key point for the early diagnosis success and the development of personalized therapies. However, it remains a challenge due to limiting factors like (i) the complexity of analyzed media, and (ii) the aspecificity detection and the poor sensitivity of the conventional methods. In addition, several applications require the integration of the primary sensors with other devices (microfluidic devices, capillaries, flasks, vials, etc.) where transducing the signal might be difficult, reducing performances and applicability. In the present work, we demonstrate a new class of optical biosensor we have developed integrating an optical waveguide (OWG) with specific plasmonic surfaces. Exploiting the plasmonic resonance, the devices give consistent results in surface enhanced Raman spectroscopy (SERS) for continuous and label-free detection of biological compounds. The OWG allows driving optical signals in the proximity of SERS surfaces (detection area) overcoming spatial constraints, in order to reach places previously optically inaccessible. A rutile prism couples the remote laser source to the OWG, while a Raman spectrometer collects the SERS far field scattering. The present biosensors were implemented by a simple fabrication process, which includes photolithography and nanofabrication. By using such devices, it was possible to detect cell metabolites like Phenylalanine (Phe), Adenosine 5-triphosphate sodium hydrate (ATP), Sodium Lactate, Human Interleukin 6 (IL6), and relate them to possible metabolic pathway variation.


Assuntos
Técnicas Biossensoriais/métodos , Óptica e Fotônica/métodos , Análise Espectral Raman/métodos , Adenosina/química , Adenosina/isolamento & purificação , Trifosfato de Adenosina/química , Trifosfato de Adenosina/isolamento & purificação , Humanos , Interleucina-6/química , Interleucina-6/isolamento & purificação , Dispositivos Lab-On-A-Chip , Limite de Detecção , Fenilalanina/química , Fenilalanina/isolamento & purificação , Lactato de Sódio/química , Lactato de Sódio/isolamento & purificação , Ressonância de Plasmônio de Superfície , Propriedades de Superfície
17.
Mar Pollut Bull ; 140: 17-29, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30803631

RESUMO

Recent technology developments have turned present-day unmanned systems into realistic alternatives to traditional marine animal survey methods. Benefits include longer survey durations, improved mission safety, mission repeatability, and reduced operational costs. We review the present status of unmanned vehicles suitable for marine animal monitoring conducted in relation to industrial offshore activities, highlighting which systems are suitable for three main monitoring types: population, mitigation, and focal animal monitoring. We describe the technical requirements for each of these monitoring types and discuss the operational aspects. The selection of a specific sensor/platform combination depends critically on the target species and its behaviour. The technical specifications of unmanned platforms and sensors also need to be selected based on the surrounding conditions of a particular offshore project, such as the area of interest, the survey requirements and operational constraints.


Assuntos
Organismos Aquáticos , Monitoramento Ambiental/instrumentação , Monitoramento Ambiental/métodos , Acústica/instrumentação , Aeronaves , Animais , Peixes , Mamíferos , Óptica e Fotônica/instrumentação , Óptica e Fotônica/métodos , Densidade Demográfica , Tartarugas
18.
J Vis Exp ; (143)2019 01 10.
Artigo em Inglês | MEDLINE | ID: mdl-30688310

RESUMO

The work presents an experiment that allows the study of many fundamental physical processes, such as photon pressure, diffraction of light or the motion of charged particles in electrical fields. In this experiment, a focused laser beam pointing upwards levitate liquid droplets. The droplets are levitated by the photon pressure of the focused laser beam which balances the gravitational force. The diffraction pattern created when illuminated with laser light can help measure the size of a trapped droplet. The charge of the trapped droplet can be determined by studying its motion when a vertically directed electrical field is applied. There are several reasons motivating this experiment to be remotely controlled. The investments required for the setup exceeds the amount normally available in undergraduate teaching laboratories. The experiment requires a laser of Class 4, which is harmful to both skin and eyes and the experiment uses voltages that are harmful.


Assuntos
Laboratórios , Óptica e Fotônica/métodos , Eletricidade , Eletrodos , Lasers , Interface Usuário-Computador
19.
Colloids Surf B Biointerfaces ; 176: 480-487, 2019 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-30684904

RESUMO

The purpose is to study the capability of the electric light scattering to determine the point of zero charge of native protein macromolecules adsorbed on colloid particles at low ionic strength and without using buffers. The chosen protein and particles are cytochrome c (cytC, globular haemoproteid) and montmorillonite (MM, negatively charged plate-like crystal). The pH-dependence of the electric polarizability γ(pH) in the range pH 6-11 shows minimum which coincides with the isoelectric point determined by measuring the electrophoretic mobility µ(pH) of the cytC-MM particles.


Assuntos
Bentonita/química , Citocromos c/química , Eletricidade , Nanopartículas/química , Óptica e Fotônica/métodos , Adsorção , Animais , Eletroforese , Cavalos , Ponto Isoelétrico , Suspensões/química
20.
Br J Ophthalmol ; 103(1): 106-111, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-29605815

RESUMO

AIMS: To analyse the predictability of diverse intraocular lens (IOL) power calculation formulae in paediatric patients with congenital cataract. METHODS: The medical records of patients who underwent cataract surgery and posterior chamber IOL implantation (in-the-bag) for congenital cataract before 17 years of age were reviewed retrospectively. Target refractions calculated by Sanders-Retzlaff-Kraff (SRK)/II, SRK/T and Hoffer-Q formulae were compared with the actual refraction. Patients were subgroup according to the age at IOL implantation (age group 0-24 months, 25-60 months, 61-120 months, 121-203 months), and we compared mean prediction error (PE) and mean absolute error (AE) for each formula. Corrected AE was obtained by linear regression analysis. RESULTS: Totally 481 eyes were included in the final analysis. Both SRK/II and SRK/T yielded the lowest mean AE in the age group 0-24 months and SRK/II yielded the lowest mean AE in the age group 25-60 months. For every formula, the mean PE was positive during the first five years of age, which converged to zero according to age as IOL implantation increases. The tendency for immediate postoperative overcorrection in younger patients (<6 years) could be improved by corrected formulae based on the linear regression equation. CONCLUSIONS: Patients with congenital cataract who underwent IOL implantation within 5 years of age showed higher AE than the older ones did. Among the three formulae evaluated, SRK/II consistently provided the best predictive result in these patients. For patients aged >10 years, all three formulae showed favourable predictive abilities.


Assuntos
Extração de Catarata , Catarata/congênito , Implante de Lente Intraocular , Lentes Intraoculares , Óptica e Fotônica/métodos , Refração Ocular/fisiologia , Adolescente , Comprimento Axial do Olho/fisiologia , Catarata/fisiopatologia , Criança , Pré-Escolar , Feminino , Humanos , Lactente , Implante de Lente Intraocular/métodos , Masculino , Estudos Retrospectivos , Acuidade Visual
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