23 results on '"Optics"'
Search Results
2. Effects of aging on optical quality and visual function.
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Martínez‐Roda, Joan A, Vilaseca, Meritxell, Ondategui, Juan C, Aguirre, Montserrat, and Pujol, Jaume
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VISION , *AGING , *VISUAL acuity , *OPTICS , *VISION disorders , *LONGITUDINAL method , *PSYCHOLOGICAL tests , *SCATTERING (Physics) , *FERRANS & Powers Quality of Life Index - Abstract
Background: We assessed the effects of aging on visual function and optical quality in a healthy adult population and provide reference values for different age ranges.Methods: We conducted a prospective study with 198 healthy volunteers from 31 to 70 years of age. The visual acuity (VA) and contrast sensitivity (CS) at 3, 6, 12 and 18 cycles per degree (cpd) frequencies were assessed, together with values of optical quality and intraocular scattering obtained with a double-pass system (Optical Quality Analysis System - OQAS), specifically the modulation transfer function cutoff frequency (MTFcutoff ), the Strehl ratio, the OQAS values (OV) at contrasts of 100, 20 and nine per cent and the objective scatter index (OSI). We studied the change of these variables with age and obtained standard values for optical quality and intraocular scattering parameters for four age groups: 31 to 40, 41 to 50, 51 to 60 and 61 to 70 years.Results: We found significant correlations between age and all variables analysed and significant differences among the age groups considered except for CS (3 cpd) (p = 0.067). Ageing particularly affected low-contrast parameters, such as the OV nine per cent and the OSI, which decreased to 37 and 50 per cent of their original values, respectively. The OSI was found to provide high sensitivity and specificity values, when healthy and caratactous eyes were considered. The results suggest that optical deficits are compensated until 50 years of age with sensory and perceptual factors, as smaller changes were found for visual function than for objective measurements of optical quality and intraocular scattering.Conclusions: Measures of optical quality assessed by subjective psychophysical and objective techniques varied differently with age. Values obtained for each age group can be used to determine normal limits of optical quality and intraocular scattering for diagnosis of ocular conditions. [ABSTRACT FROM AUTHOR]- Published
- 2016
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3. Accommodation and age-dependent eye model based on in vivo measurements
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Hema Radhakrishnan, W. Neil Charman, Norberto López-Gil, and Juan F. Zapata-Díaz
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Adult ,Original article ,Accommodation ,Aging ,genetic structures ,Aberraciones ,Eye model ,Curvature ,Modelo de ojo ,Refraction, Ocular ,Models, Biological ,Pupil ,Entrance pupil ,03 medical and health sciences ,Young Adult ,0302 clinical medicine ,Optics ,Age ,Humans ,Edad ,Acomodación ,Pupila ,Mathematics ,Aged ,Retrospective Studies ,Wavefront ,business.industry ,Paraxial approximation ,Accommodation, Ocular ,Middle Aged ,eye diseases ,Spherical aberration ,Aberrations ,030221 ophthalmology & optometry ,Female ,sense organs ,business ,030217 neurology & neurosurgery ,Photopic vision ,Optometry - Abstract
Purpose To develop a flexible model of the average eye that incorporates changes with age and accommodation in all optical parameters, including entrance pupil diameter, under photopic, natural, environmental conditions. Methods We collated retrospective in vivo measurements of all optical parameters, including entrance pupil diameter. Ray-tracing was used to calculate the wavefront aberrations of the eye model as a function of age, stimulus vergence and pupil diameter. These aberrations were used to calculate objective refraction using paraxial curvature matching. This was also done for several stimulus positions to calculate the accommodation response/stimulus curve. Results The model predicts a hyperopic change in distance refraction as the eye ages (+0.22 D every 10 years) between 20 and 65 years. The slope of the accommodation response/stimulus curve was 0.72 for a 25 years-old subject, with little change between 20 and 45 years. A trend to a more negative value of primary spherical aberration as the eye accommodates is predicted for all ages (20–50 years). When accommodation is relaxed, a slight increase in primary spherical aberration (0.008 μm every 10 years) between 20 and 65 years is predicted, for an age-dependent entrance pupil diameter ranging between 3.58 mm (20 years) and 3.05 mm (65 years). Results match reasonably well with studies performed in real eyes, except that spherical aberration is systematically slightly negative as compared with the practical data. Conclusions The proposed eye model is able to predict changes in objective refraction and accommodation response. It has the potential to be a useful design and testing tool for devices (e.g. intraocular lenses or contact lenses) designed to correct the eye's optical errors.
- Published
- 2018
4. The optical structure of the lens and its contribution to the refractive status of the eye.
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Smith, G. and Pierscionek, B. K.
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OPTICS , *REFRACTIVE index , *LENSES , *ELLIPTIC curves , *AGE , *VISUAL accommodation - Abstract
This paper uses the Wood and the elliptical lens models to consider how changes in the refractive index gradient with age and accommodation may affect ocular power. [ABSTRACT FROM AUTHOR]
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- 1998
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5. Correlation of age, corneal curvature and spherical equivalent with central corneal thickness
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Jorge E. Valdez-García, Judith Zavala, Denise Loya-Garcia, Juan F. Lozano-Ramírez, Julio C. Hernandez-Camarena, and Jesus Merayo-Lloves
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Distribución bimodal ,Equivalente esférico ,medicine.medical_specialty ,genetic structures ,Population ,Spherical equivalent ,Positive correlation ,law.invention ,Central corneal thickness ,Correlation ,03 medical and health sciences ,0302 clinical medicine ,Optics ,Age ,Age groups ,lcsh:Ophthalmology ,Bimodal distribution ,law ,Ophthalmology ,medicine ,Edad ,education ,education.field_of_study ,Corneal curvature ,Keratometer ,business.industry ,Significant difference ,eye diseases ,Queratometría ,lcsh:RE1-994 ,Grosor corneal central ,030221 ophthalmology & optometry ,sense organs ,business ,030217 neurology & neurosurgery ,Keratometry - Abstract
Objective: To describe the distribution of the central corneal thickness (CCT) measurements on a healthy Hispanic sample population and its correlation with age, mean simulated keratometry (SimK), and mean refractive spherical equivalent (MRSE). Methods: Retrospective analysis on the records of healthy patients from the Ophthalmology and Visual Sciences Institute, Tecnologico de Monterrey, January 2015 to August 2015. CCT data, age, gender, corneal curvature, and spherical equivalent was obtained. A descriptive analysis and correlation by the Spearman method was performed. The sample was divided by age subgroups: than 40 years old and correlation analysis with CCT values was determined. Results: A total of 93 (186 eyes) patients were included. Mean age: 32.54 ± 12.04 years. 43% were women. Mean CCT: 545.69 ± 36.88 μm, mean SimK: 43.56 ± 1.90 D and MRSE: −2.54 ± 3.15 D. No correlation was registered between CCT and the variables when analyzed with the Anderson–Darling (p = 0.006), Shapiro–Wilk (p = 0.043), and Kolmogorov–Smirnov (p = 0.01). CCT showed a bimodal distribution with higher density at 540 μm. Age groups 40 years showed significant difference in CCT (p = 0.016), a positive correlation with CCT was observed in the group
- Published
- 2017
6. Optical coherence tomography evidence on the correlation of choroidal thickness and age with vascularized retinal layers in normal eyes
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Vittorio Scavella, Francesco Parisi, Solmaz Abdolrahimzadeh, and Santi Maria Recupero
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Adult ,Male ,Aging ,medicine.medical_specialty ,Visual acuity ,Visual Acuity ,Spectral domain ,Retinal Pigment Epithelium ,Retina ,Young Adult ,03 medical and health sciences ,chemistry.chemical_compound ,0302 clinical medicine ,Optics ,Optical coherence tomography ,Ophthalmology ,medicine ,Humans ,Prospective Studies ,Aged ,Retinal pigment epithelium ,medicine.diagnostic_test ,Choroid ,business.industry ,Retinal ,General Medicine ,Coherence (statistics) ,Middle Aged ,eye diseases ,age ,choroidal thickness ,enhanced depth imaging ,ganglion cell layer ,glaucoma ,myopia ,neuro-ophthalmological diseases ,outer retinal layers ,spectral domain optical coherence tomography ,vascularized retinal layers ,adult ,aged ,aging ,choroid ,cross-sectional studies ,female ,humans ,male ,middle aged ,prospecpitheliu ,retina ,retinal pigment e ,Cross-Sectional Studies ,medicine.anatomical_structure ,chemistry ,030221 ophthalmology & optometry ,Female ,sense organs ,medicine.symptom ,business ,Tomography, Optical Coherence ,030217 neurology & neurosurgery - Abstract
To correlate choroidal thickness (CT) and age with vascularized retinal layer and outer retinal layer thickness in normal eyes.This was a prospective, cross-sectional study. Complete ophthalmological examination, biometry, and enhanced depth imaging spectral domain optical coherence tomography were performed. Choroidal and individual retinal layer thickness measurements were obtained. Thickness maps for all layers were evaluated using the 1 mm, 3 mm, and 6 mm early treatment diabetic retinopathy study (ETDRS) macular grid areas.One hundred and twenty eyes were included. Choroidal thickness correlated negatively with age in all ETDRS areas. The ganglion cell layer (GCL) in the 1 mm; the GCL and inner plexiform layer (IPL) in the 3 mm and 6 mm; and the GCL, IPL, and inner nuclear layer in the 6 mm areas correlated negatively with age and positively with CT. Retinal nerve fiber layer thickness in the 6 mm area correlated negatively with age. The retinal pigment epithelium-photoreceptor layer in all areas correlated negatively with age and positively with CT.In normal subjects, vascularized retinal layer thicknesses and outer retinal layer thickness correlate positively with CT and negatively with age. The role of neuronal versus vascular components should be considered when evaluating individual retinal layer thicknesses.
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- 2016
7. A comparative study on the viscoelastic properties of human and animal lenses
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Prashant K. Sharma, T. G. van Kooten, Steven A. Koopmans, H.J. Busscher, T. Terwee, Man, Biomaterials and Microbes (MBM), Personalized Healthcare Technology (PHT), and Restoring Organ Function by Means of Regenerative Medicine (REGENERATE)
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Aging ,Compressive Strength ,Sus scrofa ,law.invention ,PRESBYOPIA ,law ,Composite material ,Child ,Time constant ,Stiffness ,CAPSULE ,STIFFNESS ,MECHANICAL-PROPERTIES ,Middle Aged ,STRETCHER ,Sensory Systems ,ACCOMMODATION ,Lens (optics) ,Compressive load ,Rabbits ,medicine.symptom ,monkey ,BIOMECHANICAL MEASUREMENTS ,Adult ,Materials science ,Adolescent ,lens ,Lens Capsule, Crystalline ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Viscoelasticity ,Young Adult ,Cellular and Molecular Neuroscience ,Optics ,AGE ,Lens, Crystalline ,medicine ,Animals ,Humans ,leporine ,Elasticity (economics) ,ELASTIC CONSTANTS ,Pliability ,Aged ,business.industry ,Generalized Maxwell model ,Presbyopia ,Elastic Tissue ,medicine.disease ,porcine ,Macaca mulatta ,eye diseases ,Ophthalmology ,HUMAN CRYSTALLINE LENS ,elasticity ,sense organs ,business - Abstract
A new method of compression between two parallel plates is used to measure the viscoelastic properties of whole and decapsulated human lenses and compare them with other animal species. Compressive load relaxation was performed by deforming the lens by 10% and measuring the force relaxation response for 100s to obtain thickness, stiffness and relaxation of the induced loading force and Maxwell parameters for human, monkey, porcine and leporine whole and decapsulated lenses. Thickness and percentage loading force relaxation increased linearly with lens age, whereas stiffness and induced loading force increased exponentially. Human and monkey lenses aged at different rates. Loading force relaxation in a generalized Maxwell model was described by three time constants ranging from 1 to 1000 s. Compressive load relaxation is a very versatile method to study the viscoelastic properties of whole and decapsulated lenses and potentially also artificial accommodating lenses. The data presented in the study will help researchers choose the most suitable animal lenses based on the desired properties and age to be mimicked from the human lenses. (C) 2011 Elsevier Ltd. All rights reserved.
- Published
- 2011
8. Effects of age, viewing distance and target complexity on static ocular counterroll
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Khaled Abuhaleeqa, Joanne C.Y. Leung, Herbert C. Goltz, Alan Blakeman, Agnes M. F. Wong, Linda Colpa, and Giuseppe Mirabella
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Adult ,Male ,Aging ,Adolescent ,Eye Movements ,Computer science ,Posture ,Video Recording ,Vergence ,Fixation, Ocular ,Otolith ,Article ,03 medical and health sciences ,Young Adult ,Age ,0302 clinical medicine ,Optics ,Form perception ,Reflex ,Humans ,Computer vision ,030223 otorhinolaryngology ,Vestibular system ,Video recording ,Analysis of Variance ,business.industry ,Distance Perception ,Eye movement ,Convergence, Ocular ,Middle Aged ,Sensory Systems ,Vestibular ,Form Perception ,OCR ,Ophthalmology ,Tilt (optics) ,Head Movements ,Head movements ,Female ,Target characteristics ,Artificial intelligence ,business ,030217 neurology & neurosurgery - Abstract
The ocular counterroll (OCR) reflex generates partially compensatory torsional eye movements during static head roll tilt. We assessed the influence of age, viewing distance and target complexity on the OCR across the age span (13-63 years; n=47), by recording eye movements during head-on-body roll tilt (0+/-40 degrees in 5 degrees steps) while subjects viewed simple vs. complex targets at 0.33 and 1m. We found that subjectsor = 31 years had lower gains than thoseor =30 years, but only for far targets. Consistent with prior reports, far targets elicited higher OCR gains than near targets, and target complexity had no effect on gains, suggesting that visual input is primarily used to maintain vergence during OCR.
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- 2009
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9. Skin autofluorescence for the risk assessment of chronic complications in diabetes
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Reindert Graaff, Rijk O. B. Gans, HL Lutgers, Andries J. Smit, Thera P. Links, R. de Vries, M. Koetsier, Gerhard Rakhorst, Groningen Kidney Center (GKC), Vascular Ageing Programme (VAP), University of Groningen, Damage and Repair in Cancer Development and Cancer Treatment (DARE), Guided Treatment in Optimal Selected Cancer Patients (GUTS), Man, Biomaterials and Microbes (MBM), and Lifestyle Medicine (LM)
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Adult ,Male ,DIFFUSE-REFLECTANCE SPECTROSCOPY ,Ultraviolet Rays ,ENDPRODUCTS ,Risk Assessment ,Fluorescence ,Diabetes Complications ,Optics ,AGE ,Diabetes mellitus ,Skin Physiological Phenomena ,medicine ,Humans ,INSTRUMENTATION ,OXIDATIVE STRESS ,IN-VIVO ,ACCUMULATION ,business.industry ,Skin autofluorescence ,Middle Aged ,medicine.disease ,Control subjects ,Atomic and Molecular Physics, and Optics ,Clinical method ,Light intensity ,Increased risk ,FLUORESCENCE SPECTROSCOPY ,MARKER ,Chronic Disease ,Luminescent Measurements ,Female ,business ,Risk assessment ,GLYCATION END-PRODUCTS ,Excitation - Abstract
Skin autofluorescence (AF) is becoming an accepted clinical method for assessing the risk of chronic complications in diabetes mellitus (DM). In this study, the role of the excitation wavelength in the recognition of increased risk of diabetes-related chronic complications was investigated. An Excitation Emission Matrix Scanner (EEMS) was used to perform non-invasive measurements in four age-matched groups of patients with type 1 and type 2 DM, with and without chronic complications, as well as in a control group (N=97 in total). AF was calculated for excitation wavelengths in the range 355 - 405 nm. Mean spectra were assessed per group. AF values in both type 1 and type 2 DM patients with complications were increased compared to the control subjects (p
- Published
- 2009
10. Relation between injected volume and optical parameters in refilled isolated porcine lenses
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Thom Terwee, Aart C. Kooijman, Henk Deuring, Henk J. Haitjema, Steven A. Koopmans, and Sonja van Aarle
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accommodation ,CRYSTALLINE LENS ,Aging ,Optics and Photonics ,intra-ocular lens ,Swine ,law.invention ,surgery ,chemistry.chemical_compound ,law ,Silicone Oils ,CAPSULE ,Accommodation, Ocular ,Sensory Systems ,Silicone oil ,Lens (optics) ,Spherical aberration ,medicine.anatomical_structure ,lens capsule refilling ,SHAPE ,lens senescence ,Materials science ,POWER ,Lens Capsule, Crystalline ,Refraction, Ocular ,Drug Administration Schedule ,AGE ,Optics ,Ciliary body ,Silicone ,Lens, Crystalline ,medicine ,Animals ,PLUG ,business.industry ,Ciliary Body ,restoration of accommodation ,IN-VITRO ,Presbyopia ,medicine.disease ,Ophthalmology ,Volume (thermodynamics) ,chemistry ,REFRACTIVE-INDEX DISTRIBUTION ,silicone ,sense organs ,business ,Refractive index ,Optometry - Abstract
Purpose: This study was performed to elucidate the correlation between added lens refill material and enhanced lens power as well as the correlation between lens refilling volume and accommodative amplitude as determined by equatorial stretching of ex vivo refilled pigs' lenses. Methods: Nine porcine lenses were refilled with increasing amounts of silicone oil. After each refill step, the lens power, the lens power change, and the lens thickness were measured both in the relaxed state and with a 3-mm larger ciliary body diameter. In addition, the spherical aberration of the refilled lenses was also quantified. Results: Injection of 0.04 mL silicone material into the relaxed lens enhanced the lens power by 1 D. A 0.54-mm increase of the lens thickness in relaxed lenses added 1 D to the lens power. Increasing the lens refilling volume decreased the lens power changes measured at 3-mm ciliary body stretch. Spherical aberration was positive in the refilled lenses and increased with increasing lens refilling volume. Conclusion: The correlation found between the refilling volume and the lens power (0.04 mL D-1), as well as the correlation between the lens thickness and the lens power (0.54 mm D-1), might be important factors to be controlled in conjunction with surgery, as these also determine the lens power in the presence of this refill material. An increasing lens filling volume is associated with decreasing accommodative amplitude. The positive spherical aberration of refilled porcine lenses presents a sharp contrast to the negative aberration of natural pigs' lenses. Different lens contours and the transition from a gradient to a homogeneous refractive index might be responsible for this change in spherical aberration.
- Published
- 2004
11. Technical improvements applied to a double-pass setup for performance and cost optimization
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Carlos E. García-Guerra, Mikel Aldaba Arévalo, Fernando Díaz-Doutón, Jaume Pujol Ramo, Ferran Sanabria, Universitat Politècnica de Catalunya. Departament d'Òptica i Optometria, and Universitat Politècnica de Catalunya. GREO - Grup de Recerca en Enginyeria Òptica
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Point spread function ,Electrooptics ,eye refraction ,Computer science ,ComputingMethodologies_IMAGEPROCESSINGANDCOMPUTERVISION ,Electroòptica ,Ulls -- Acomodació i refracció ,RETINAL-IMAGE QUALITY ,ABERRATIONS ,law.invention ,Double pass ,Speckle pattern ,WAVE-FRONT SENSOR ,Optics ,AGE ,law ,Díodes ,Lents líquides ,Electronic engineering ,tunable lens ,OPTICAL-QUALITY ,IN-SITU KERATOMILEUSIS ,optical quality ,CMOS sensor ,Laser diode ,laser diode ,double-pass ,business.industry ,Scattering ,Quality control--Optical methods ,Eye--Refractive errors ,Enginyeria electrònica::Optoelectrònica [Àrees temàtiques de la UPC] ,Liquid lenses ,scattering ,General Engineering ,HUMAN EYE ,Superluminescent diode ,HARTMANN-SHACK SENSOR ,Diodes ,Atomic and Molecular Physics, and Optics ,POINT-SPREAD FUNCTION ,Lens (optics) ,electro-optical liquid lens ,CMOS ,Ciències de la visió::Optometria [Àrees temàtiques de la UPC] ,superluminescent diode ,business ,SYSTEM - Abstract
We have studied the possibility of improving the performance, simplifying, and reducing the cost of a double-pass system by the use of alternative technologies. The system for correcting the spherical correction has been based on a focusable electro-optical lens, and a recording device based on CMOS technology and a superluminescent diode (SLED) light source have been evaluated separately. The suitability of the CMOS camera has been demonstrated, while the SLED could not break the speckle by itself. The final experimental setup, consisting of a CMOS camera and a laser diode, has been compared with a commercial double-pass system, proving its usefulness for ocular optical quality and scattering measurements. (C) 2014 Society of Photo-Optical Instrumentation Engineers (SPIE)
- Published
- 2014
12. Biometric, optical and physical changes in the isolated human crystalline lens with age in relation to presbyopia
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Adrian Glasser and Melanie C. W. Campbell
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Male ,Aging ,Optics and Photonics ,Refractive error ,genetic structures ,Physics::Optics ,law.invention ,0302 clinical medicine ,law ,Child ,Dioptre ,Aged, 80 and over ,Anthropometry ,Middle Aged ,Refraction ,Sensory Systems ,Lens (optics) ,Spherical aberration ,Child, Preschool ,Female ,Adult ,Accommodation ,Adolescent ,Lens Capsule, Crystalline ,Astrophysics::Cosmology and Extragalactic Astrophysics ,In Vitro Techniques ,Refraction, Ocular ,03 medical and health sciences ,Age ,Optics ,Lens, Crystalline ,medicine ,Humans ,Focal length ,Crystalline lens ,Aged ,business.industry ,Presbyopia ,medicine.disease ,Ophthalmology ,030221 ophthalmology & optometry ,Stress, Mechanical ,sense organs ,business ,Refractive index ,Mathematics ,030217 neurology & neurosurgery - Abstract
The biometric, optical and physical properties of 19 pairs of isolated human eye-bank lenses ranging in age from 5 to 96 years were compared. Lens focal length and spherical aberration were measured using a scanning laser apparatus, lens thickness and the lens surface curvatures were measured by digitizing the lens profiles and equivalent refractive indices were calculated for each lens using this data. The second lens from each donor was used to measure resistance to physical deformation by providing a compressive force to the lens. The lens capsule was then removed from each lens and each measurement was repeated to ascertain what role the capsule plays in determining these optical and physical characteristics. Age dependent changes in lens focal length, lens surface curvatures and lens resistance to physical deformation are described. Isolated lens focal length was found to be significantly linearly correlated with both the anterior and posterior surface curvatures. No age dependent change in equivalent refractive index of the isolated lens was found. Although decapsulating human lenses causes similar changes in focal length to that which we have shown to occur when human lenses are mechanically stretched into an unaccommodated state, the effects are due to nonsystematic changes in lens curvatures. These studies reinforce the conclusion that lens hardening must be considered as an important factor in the development of presbyopia, that age changes in the human lens are not limited to the loss of accommodation that characterizes presbyopia but that the lens optical and physical properties change substantially with age in a complex manner.
- Published
- 1999
13. Adaptive model of the gradient index of the human lens. I. Formulation and model of aging ex vivo lenses
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Rafael Navarro, L. González, and Fernando Palos
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Adult ,Aging ,Optics and Photonics ,Quadric ,Adolescent ,Concentric ,Models, Biological ,law.invention ,Optics ,Age ,Simple (abstract algebra) ,law ,Lens, Crystalline ,Humans ,Aged ,Parametric statistics ,Mathematics ,Aged, 80 and over ,Crystalline ,business.industry ,Middle Aged ,Adaptive ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,Index ,Lens (optics) ,Refractometry ,Spherical aberration ,Distribution (mathematics) ,sense organs ,Computer Vision and Pattern Recognition ,business ,Refractive index ,Algorithms - Abstract
11 pages., A simple, parametric adaptive model of the refractive index distribution of the ex vivo crystalline lens is presented. It assumes conicoid (or nonrevolution quadric in 3D) iso-indical surfaces, concentric with the external surfaces of the lens. The model uses a minimum number of internal structural parameters, while the shape of the iso-indical surfaces adapts automatically to the external geometry. In this way, it is able to adapt and fit individual distributions as well as adapt to the changes of the lens shape and structure with age and accommodation. The model is fit to experimental data for individual eyes spanning ages 7 to 82 years, where for each eye the crystalline lens dimensions and iso-indical index data are known. The analysis demonstrates that only one age-dependent structural parameter is needed to replicate the internal iso-indical index structure, given age-dependent models for the external surfaces. An age-dependent-parameter global model is derived and is shown to predict age-dependent changes in the ex vivo lens power and longitudinal spherical aberration with age.
- Published
- 2007
14. Accommodation as a function of age and the linearity of the response dynamics
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William N. Charman and Gordon Heron
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Adult ,Accommodation ,medicine.medical_specialty ,Aging ,Adolescent ,Extrapolation ,Poison control ,Stimulus (physiology) ,Audiology ,Age ,Optics ,Vision, Monocular ,Linear regression ,medicine ,Reaction Time ,Humans ,Gain ,business.industry ,Linear system ,Linearity ,Accommodation, Ocular ,Presbyopia ,Middle Aged ,medicine.disease ,Sensory Systems ,Dynamics ,Ophthalmology ,Phase ,business ,Psychology ,Photic Stimulation - Abstract
The changes with age in the accommodation responses to dynamic stimuli can reveal useful information on the factors underlying presbyopia development. Analysis of the monocular accommodation responses of 19 normal observers (ages 18–49 years) to stimuli whose vergence varied sinusoidally with time at different temporal frequencies (peak-to-peak stimulus 1.33–2.38D, at 0.05–1.00Hz) showed that at all ages both the gain and phase of the response were essentially linear functions of the temporal frequency. Extrapolation of least-squares, regression line fits to the gain data for each subject gave the gain at zero frequency, G0, and the cut-off frequency, fc, at which the gain fell to zero. G0 reduced with age but fc remained essentially constant at about 1.7Hz, up to at least the age of about 40. The magnitude of the response to step stimuli covering the same stimulus range was well correlated with the value of G0. The linear changes in phase lag with temporal frequency corresponded to simple time delays td. The time lag varied from close to zero for the youngest subjects to about 0.5s for the subjects in their late forties. There was substantial variation between the responses of subjects of similar age: those subjects with high values of G0 also tended to have low values of td, both effects probably being due to the superior ability of some individuals to predict the sinusoidal changes in the accommodation stimulus. Comparison of theoretical step responses, derived by applying linear theory to the parameters obtained from the results for the sinusoidal stimuli, with the actual responses to unpredictable steps for the same subjects supports the view that prediction effects and other possible factors make linear theory inapplicable to this type of data. The results are discussed in the context of current ideas on the development of presbyopia: it is suggested that the constancy of fc with age is the result of the ciliary body maintaining its efficiency, whereas the fall in G0 and increase in td result from increases in lens rigidity.
- Published
- 2004
15. Spherical and irregular aberrations are important for the optimal performance of the human eye
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Nomdo M. Jansonius, Y. K. Nio, Sverker Norrby, Aart C. Kooijman, V. Fidler, and E. Geraghty
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modulation transfer ,Depth of focus ,genetic structures ,OPTICAL ABERRATIONS ,Eye ,Models, Biological ,adaptive optics ,Contrast Sensitivity ,Optics ,AGE ,monochromatic aberrations ,Optical transfer function ,medicine ,Humans ,DEFOCUS ,Adaptive optics ,Vision, Ocular ,Physics ,business.industry ,Adaptation, Ocular ,Vision Tests ,ABERROSCOPE ,spatial vision ,SENSOR ,Sensory Systems ,eye diseases ,ACCOMMODATION ,Ophthalmology ,Spherical aberration ,medicine.anatomical_structure ,refractive surgery ,Human eye ,Spatial frequency ,sense organs ,business ,Focus (optics) ,IMAGE QUALITY ,Optometry ,Optical aberration - Abstract
Contrast sensitivity measured psychophysically at different levels of defocus can be used to evaluate the eye optics. Possible parameters of spherical and irregular aberrations, e.g. relative modulation transfer (RMT), myopic shift, and depth of focus, can be determined from these measurements. The present paper compares measured results of RMT, myopic shift, and depth of focus with the theoretical results found in the two eye models described by Jansonius and Kooijman (1998). The RMT data in the present study agree with those found in other studies, e.g. Campbell and Green (1965) and Jansonius and Kooijman (1997). A new theoretical eye model using a spherical aberration intermediate between those of the eye models described by Jansonius and Kooijman (1998) and an irregular aberration with a typical S.D. of 0.3-0.5 D could adequately explain the measured RMT, myopic shift, and depth of focus data. Both spherical and irregular aberrations increased the depth of focus, but decreased the modulation transfer (MT) at high spatial frequencies at optimum focus. These aberrations, therefore, play an important role in the balance between acuity and depth of focus.
- Published
- 2002
16. A unified formula for light-adapted pupil size
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Andrew B. Watson and John I. Yellott
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accommodation ,retina ,Observer (quantum physics) ,Image quality ,Photoperiod ,contrast sensitivity function ,ComputingMethodologies_IMAGEPROCESSINGANDCOMPUTERVISION ,Adaptation (eye) ,Luminance ,Field (computer science) ,Pupil ,Dilation (metric space) ,Optics ,senile miosis ,Medicine and Health Sciences ,Humans ,image quality ,Arithmetic ,diameter ,light adaptation ,Adaptation, Ocular ,business.industry ,illumination ,retinal illuminance ganglion-cells ,Models, Theoretical ,pupil diameter ,Sensory Systems ,Ophthalmology ,age ,pupil reflex ,responses ,dilation ,business ,Psychology ,Accommodation - Abstract
The size of the pupil has a large effect on visual function, and pupil size depends mainly on the adapting luminance, modulated by other factors. Over the last century, a number of formulas have been proposed to describe this dependence. Here we review seven published formulas and develop a new unified formula that incorporates the effects of luminance, size of the adapting field, age of the observer, and whether one or both eyes are adapted. We provide interactive demonstrations and software implementations of the unified formula.
- Published
- 2012
17. Geometry-invariant GRIN lens: iso-dispersive contours
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Mehdi Bahrami and Alexander V. Goncharov
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crystalline lens ,accommodation ,Abbe number ,Physics::Optics ,longitudinal chromatic aberration ,law.invention ,ocis:(220.1000) Aberration compensation ,Optics ,Vision and Visual Optics ,law ,ocis:(110.2760) Gradient-index lenses ,Dispersion (optics) ,Chromatic aberration ,Physics ,model ,Simple lens ,business.industry ,ocis:(330.7326) Visual optics, modeling ,Atomic and Molecular Physics, and Optics ,Lens (optics) ,human-eye ,age ,Achromatic lens ,ocular media ,ocis:(080.1005) Aberration expansions ,Gradient-index optics ,refractive-index distribution ,gradient-index ,vivo ,business ,physics ,Refractive index ,biological ,Biotechnology - Abstract
A dispersive model of a gradient refractive index (GRIN) lens is introduced based on the idea of iso-dispersive contours. These contours have constant Abbe number and their shape is related to iso-indicial contours of the monochromatic geometry-invariant GRIN lens (GIGL) model. The chromatic GIGL model predicts the dispersion throughout the GRIN structure by using the dispersion curves of the surface and the center of the lens. The analytical approach for paraxial ray tracing and the monochromatic aberration calculations used in the GIGL model is employed here to derive closed-form expressions for the axial and lateral color coefficients of the lens. Expressions for equivalent refractive index and the equivalent Abbe number of the homogeneous equivalent lens are also presented and new aspects of the chromatic aberration change due to aging are discussed. The key derivations and explanations of the GRIN lens optical properties are accompanied with numerical examples for the human and animal eye GRIN lenses.
- Published
- 2012
18. Changes in Spherical Aberration after Lens Refilling with a Silicone Oil
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Steven A. Koopmans, Aart C. Kooijman, T. Terwee, and Kwok-Hoi Wong
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Materials science ,Pseudophakia ,genetic structures ,Swine ,medicine.medical_treatment ,POWER ,Lens Capsule, Crystalline ,Mineralogy ,Optical power ,Intraocular lens ,Refraction, Ocular ,law.invention ,PRESBYOPIA ,AGE ,Optics ,law ,Lens, Crystalline ,medicine ,Animals ,Silicone Oils ,INTRAOCULAR-LENS ,PLUG ,Phacoemulsification ,business.industry ,HUMAN EYE ,IN-VITRO ,Presbyopia ,Refractive Errors ,medicine.disease ,Capsulorhexis ,ACCOMMODATION ,eye diseases ,Lens (optics) ,Refractometry ,Spherical aberration ,medicine.anatomical_structure ,Human eye ,Gradient-index optics ,sense organs ,business ,Refractive index - Abstract
PURPOSE. It may be possible to restore accommodation to presbyopic human eyes by refilling the lens capsular bag with a soft polymer. In the present study, optical changes were measured that occurred in a pig eye model after the refilling of the capsular bag.METHODS. The optical power and spherical aberration in 10 isolated pig lenses were measured under different conditions. They were first determined by using a scanning laser raytracing technique over an effective pupil size of 6 mm. Second, the contours of the anterior and posterior lens surface were photographed, and a mathematical ray-tracing was performed by using a polynomial fit through the digitized surface contours, to determine optical power and spherical aberration. Third. the lenses were refilled with a silicone oil until their preoperative lens thickness was reached, and scanning laser ray-tracing, contour photography, and mathematical ray-tracing were repeated. Comparisons between the measurements were made to determine how the change from a gradient refractive index to a homogeneous refractive index influenced spherical aberration. The influence of the change in lens contour on spherical aberration after lens refilling was also studied.RESULTS. The natural lenses had a higher lens power than the refilled lenses (49.9 +/- 1.5 D vs. 36.8 +/- 1.5 D; P CONCLUSIONS. The lower lens power of refilled pig lenses compared to natural lenses was due to the lower refractive index of the refill material. Refilling pig lenses with the silicone oil used in this study resulted in an increase in spherical aberration. This increase was mainly caused by the change from a gradient refractive index to a homogeneous refractive index. The change in lens curvature after lens refilling did not result in an increase in spherical aberration. The influence of lens refilling on spherical aberration of human lenses must be determined in similar experiments in human eyes.
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- 2007
19. Presbyopia and the optical changes in the human crystalline lens with age
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Adrian Glasser and Melanie C. W. Campbell
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Adult ,Aging ,Optics and Photonics ,Refractive error ,Accommodation ,Materials science ,Adolescent ,genetic structures ,In Vitro Techniques ,Refraction, Ocular ,law.invention ,03 medical and health sciences ,Lens ,0302 clinical medicine ,Optics ,Ciliary body ,Age ,law ,Lens, Crystalline ,medicine ,Humans ,Focal length ,Spherical aberration ,Child ,10. No inequality ,Aged ,030304 developmental biology ,Aged, 80 and over ,0303 health sciences ,Crystalline ,business.industry ,Ciliary Body ,Accommodation, Ocular ,Presbyopia ,Middle Aged ,medicine.disease ,Refraction ,Sensory Systems ,eye diseases ,Lens (optics) ,Ophthalmology ,medicine.anatomical_structure ,030221 ophthalmology & optometry ,Stress, Mechanical ,sense organs ,business - Abstract
Lenses from 27 human eyes ranging in age from 10 to 87 years were used to determine how accommodation and age affect the optical properties of the lens. A scanning laser technique was used to measure focal length and spherical aberration of the lenses, while the lenses were subjected to stretching forces applied through the ciliary body/zonular complex. The focal length of all unstretched lenses increased linearly with increasing age. Younger lenses were able to undergo significant changes in focal length with stretching, whereas lenses older than 60 years of age showed no changes in focal length with stretching. These data provide additional evidence for predominantly lens-based theories of presbyopia. Further, these results show that there are substantial optical changes in the human lens with increasing age and during accommodation, since both the magnitude and the sign of the spherical aberration change with age and stretching. These results show that the optical properties of the older presbyopic lens are quite different from the younger, accommodated lens.
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20. In vitro dimensions and curvatures of human lenses
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Jean-Marie A. Parel, A. Rosen, Fabrice Manns, Viviana Fernandez, Robert C. Augusteyn, David Borja, David B. Denham, and Arthur Ho
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Adult ,Male ,Aging ,Refractive error ,Accommodation ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Human lens ,Curvature ,law.invention ,Radius of curvature (optics) ,Optics ,Age ,law ,Lens, Crystalline ,Image Processing, Computer-Assisted ,medicine ,Humans ,Shape factor ,Aged ,Aged, 80 and over ,Physics ,business.industry ,Accommodation, Ocular ,Shape ,Presbyopia ,Middle Aged ,Shadowphotogrammetry ,medicine.disease ,Sensory Systems ,Sagittal plane ,Lens (optics) ,Optical comparator ,Ophthalmology ,medicine.anatomical_structure ,Photogrammetry ,Female ,business - Abstract
The purpose of this study was to determine dimensions and curvatures of excised human lenses using the technique of shadowphotogrammetry. A modified optical comparator and digital camera were used to photograph magnified sagittal and coronal lens profiles. Equatorial diameter, anterior and posterior sagittal thickness, anterior and posterior curvatures, and shape factors were obtained from these images. The data were used to calculate lens volumes, which were compared with the lens weights. Measurements were made on 37 human lenses ranging in age from 20 to 99 years. These showed that lens dimensions and the anterior radius of curvature increase linearly throughout adult life while posterior curvature remains constant. The relative shape (or aspect ratio) of the posterior lens is unchanged through adult life since both equatorial diameter and posterior thickness increase at the same rate. The ratio of anterior thickness to posterior thickness is constant at 0.70. It is suggested that in vivo forces alter the apparent location of the lens equator, that the in vitro lens shape corresponds to the maximally accommodated shape in vivo and that the shapes of the accommodated and unaccommodated lens progressively converge toward each other due to lens growth with age, with a convergence point located near the age of total loss of accommodation (55–60 years). Together, these observations provide additional support for the Helmholtz theory of accommodation.
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21. Age-Related Changes to the Three-Dimensional Full Shape of the Isolated Human Crystalline Lens
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Eduardo Martinez-Enriquez, Ashik Mohamed, Susana Marcos, Fabrice Manns, N. Geetha Sravani, Alberto de Castro, Marco Ruggeri, Ministerio de Ciencia, Innovación y Universidades (España), European Research Council, European Commission, Consejo Superior de Investigaciones Científicas (España), National Eye Institute (US), Hyderabad Eye Research Foundation, Florida Lions Eye Bank, and Beauty of Sight Foundation
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Surface (mathematics) ,Adult ,Aging ,Materials science ,Adolescent ,Curvature ,01 natural sciences ,law.invention ,010309 optics ,03 medical and health sciences ,Young Adult ,0302 clinical medicine ,Optics ,Imaging, Three-Dimensional ,Age ,Optical coherence tomography ,law ,Position (vector) ,Visual Psychophysics and Physiological Optics ,0103 physical sciences ,Lens, Crystalline ,medicine ,Humans ,Child ,medicine.diagnostic_test ,business.industry ,Plane (geometry) ,Infant, Newborn ,Infant ,Presbyopia ,Middle Aged ,medicine.disease ,eye diseases ,Lens (optics) ,OCT ,Child, Preschool ,030221 ophthalmology & optometry ,Tomography ,sense organs ,business ,Tomography, Optical Coherence ,Lens shape - Abstract
11 pags., 4 figs., 4 tabs., PURPOSE. Studying the full shape crystalline lens geometry is important to understand the changes undergone by the crystalline lens leading to presbyopia, cataract, or failure of emmetropization, and to aid in the design and selection of intraocular lenses and new strategies for correction. We used custom-developed three-dimensional (3-D) quantitative optical coherence tomography (OCT) to study age-related changes in the full shape of the isolated human crystalline lens. METHODS. A total of 103 ex vivo human isolated lenses from 87 subjects (age range, 0-56 years) were imaged using a 3-D spectral-domain OCT system. Lens models, constructed after segmentation of the surfaces and distortion correction, were used to automatically quantify central geometric parameters (lens thickness, radii of curvatures, and asphericities of anterior and posterior surfaces) and full shape parameters (lens volume, surface area, diameter, and equatorial plane position). Age-dependencies of these parameters were studied. RESULTS. Most of the measured parameters showed a biphasic behavior, statistically significantly increasing (radii of curvature, lens volume, surface area, diameter) or decreasing (asphericities, lens thickness) very fast in the first two decades of life, followed by a slow but significant increase after age 20 years (for all the parameters except for the posterior surface asphericity and the equatorial plane position, that remained constant). CONCLUSIONS. Three-dimensional quantitative OCT allowed us to study the age-dependency of geometric parameters of the full isolated human crystalline lens. We found that most of the lens geometric parameters showed a biphasic behavior, changing rapidly before age 20 years and with a slower linear growth thereafter., Supported by the Ministerio de Educación y Ciencia, Spain (FIS2017- 84753-R), European Research Council (ERC-2011- AdG-294099), and IMCUSTOMEYE Ref. 779960 (H2020-ICT2017-1) (SM), and European Research Council under Euro pean Union’s Horizon 2020 research and innovation programme H2020-MSCA COFUND-2015 FP-713694, MULTIPLY (AdC), Consejo Superior de Investigaciones Científicas ICoop Program, National Eye Institute (Grants 2R01EY021834, P30EY14801) (Center Grant), the Hyderabad Eye Research Foundation, Florida Lions Eye Bank and the Beauty of Sight Foundation, and an unrestricted grant from Research to Prevent Blindness
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22. Synaptic Adjustment after Deafferentation of the Superior Colliculus of the Rat
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Lund, R. D. and Lund, J. S.
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- 1971
23. Activity-Dependent K$^{+}$ Accumulation in the Developing Rat Optic Nerve
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Connors, Barry W., Ransom, Bruce R., Kunis, David M., and Gutnick, Michael J.
- Published
- 1982
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