Ophthalmic and Physiological Optics

Items from 1 to 20 out of 107 results

article

Investigation of the causes of non‐tolerance to optometric prescriptions for spectacles

Catherine E. Freeman, Bruce J. W. Evans

Ophthalmic and Physiological Optics > 30 > 1 > 1 - 11

Objectives: To study non‐tolerance to spectacle prescriptions in a busy community optometric practice, with several practitioners. Methods: A spectacle non‐tolerance was defined in a pragmatic way, as a patient who had collected spectacles from the practice and subsequently returned because they were either having problems with, or were unable to wear, their new spectacles. Patients over 16 years...

article

Discriminate characteristics of photopsia in posterior vitreous detachment, retinal tears and retinal detachment

Jonathan F. B. Goodfellow, Bataung Mokete, Tom H. Williamson

Ophthalmic and Physiological Optics > 30 > 1 > 20 - 23

Aims: To characterize photopsia in posterior vitreous detachment (PVD), retinal tears (RT) and rhegmatogenous retinal detachment (RRD). Methods: Seventy seven patients presenting to an eye emergency department and vitreoretinal clinic with photopsia had documentation of their symptoms. Results: A total of 27 patients had PVD alone, 7 had RTs and 25 RRD. In patients with isolated PVD, photopsia...

article

Nodes and nodal points and lines in eyes and other optical systems

W. F. Harris

Ophthalmic and Physiological Optics > 30 > 1 > 24 - 42

The typical stigmatic optical system has two nodal points: an incident nodal point and an emergent nodal point. A ray through the incident nodal point emerges from the system through the emergent nodal point with its direction unchanged. In the presence of astigmatism nodal points are not possible in most cases. Instead there are structures, called nodes in this paper, of which nodal points are special...

article

Animal‐eyeball vs. road‐sign retroreflectors

Nathaniel R. Greene, Brian J. Filko

Ophthalmic and Physiological Optics > 30 > 1 > 76 - 84

The retroreflective characteristics of ex‐vitro cow and deer eyeballs were compared to those of man‐made materials used in road signs and bicycle‐style reflectors. Reflected intensities were measured using a goniometer that consists of a green He‐Ne laser as the light source, and a photomultiplier tube as the detector. It was found that the best quality road‐sign reflector, made from a 200‐micron‐scale,...

article

Discriminating colors through a red filter by protanopes and colour normals

Vasile Diaconu, David Sullivan, Jean F. Bouchard, Valentina Vucea

Ophthalmic and Physiological Optics > 30 > 1 > 66 - 75

Individuals with color vision deficiency have difficulties in differentiating colour in their daily activities. Through certain coloured filters, dichromats may report an improvement of their capacity to differentiate colors, but it is not known if this is achieved by means of a chromatic mechanism. The present study attempts to explain the mechanism by which a coloured filter can produce a beneficial...

article

Quantification of heterophoria and phoria adaptation using an automated objective system compared to clinical methods

Sang J. Han, Yi Guo, Bérangère Granger‐Donetti, Vincent R. Vicci, more

Ophthalmic and Physiological Optics > 30 > 1 > 95 - 107

Purpose: To develop a system with which to quantify objectively the heterophoria to be measured throughout eye movement experiments. This study compared precision, resolution and accuracy characteristics of a limbus eye movement tracking system to the alternate cover test and the Maddox rod. Methods: Precision testing was performed using each technique with binocularly‐normal subjects at different...

article

Effect of chromatic mechanisms on the detection of mesopic incremental targets at different eccentricities

Peter Bodrogi, Zoltán Vas, Nils Haferkemper, Géza Várady, more

Ophthalmic and Physiological Optics > 30 > 1 > 85 - 94

Spectral sensitivity functions for the threshold detection of mesopic incremental targets were compared for different target eccentricities (10, 20, and 30°) and for different mesopic backgrounds (0.1, 0.5 and 1.0 cd m⁻²). Relative responsivities of achromatic mechanisms (L + M and rods) and chromatic mechanisms (S and |L–M|) were estimated for each eccentricity and background. Chromatic mechanisms...

article

Do multipurpose contact lens disinfecting solutions work effectively against non‐FDA/ISO recommended strains of bacteria and fungi?

Maureen Boost, Sindy Lai, Cathy Ma, Pauline Cho

Ophthalmic and Physiological Optics > 30 > 1 > 12 - 19

Purpose: Recent outbreaks of microbial keratitis have increased concerns about the efficacy of multipurpose solutions (MPS) against ‘real‐world’ organisms. This study determined, in accordance with FDA/ISO standard methods, the effects of five MPS against clinical isolates and type strains of bacteria, and isolates of fungi from subjects’ ocular structures; and of three MPS against environmental...

article

Reconstructing ocular surfaces by Purkinje images using an exact ray approach: estimating IOL decenter and tilt

Jason Turuwhenua

Ophthalmic and Physiological Optics > 30 > 1 > 43 - 54

Recently, an alternate method for recovering the shape of the anterior surface of an intraocular lens (IOL) (by Purkinje images), and capable of returning a Zernike polynomial representation of that surface, was proposed (Ophthal. Physiol Opt., 29, 2009, 80–91). However, in moving toward a clinically applicable method, it is important to estimate parameters such as surface radius, lens tilt and decenter...

article

Comparison of the IOPen^® and iCare^® rebound tonometers with the Goldmann tonometer in a normal population

J. Jorge, P. Fernandes, A. Queirós, P. Ribeiro, more

Ophthalmic and Physiological Optics > 30 > 1 > 108 - 112

This study proposes to evaluate the level of accuracy of intraocular pressure (IOP) measurements of a second generation rebound tonometer (IOPen^®), taking as references the Goldmann Applanation Tonometer (GAT) and the iCare^® rebound tonometer. The right eyes of 101 consecutive clinical patients were assessed with the three tonometers. The IOPen^® and iCare^® measurements were taken by two different...

article

Assessing visual activities of daily living in the visually impaired

Keziah Latham, Claire Usherwood

Ophthalmic and Physiological Optics > 30 > 1 > 55 - 65

Purpose: Visual function assessment questionnaires ask people to rate the difficulty they have performing visual activities of daily living (ADLs). This study examines the relationship between self‐reported difficulty and actual performance in such ADLs. Methods: Twenty four subjects with established bilateral visual impairment initially self‐reported their difficulty with 4 ADLs (reading newsprint,...

article

Effect of letter separation on computerised visual acuity measurements: comparison with the gold standard Early Treatment Diabetic Retinopathy Study (ETDRS) chart

Nilpa Shah, D. Alistair H. Laidlaw, Graham Brown, Chloe Robson

Ophthalmic and Physiological Optics > 30 > 2 > 200 - 203

Contour interaction plays an important role in letter recognition and has long been known to influence clinical visual acuity measurements. LogMAR charts originally employed between – letter and line spacing of one letter width/height; however, in more recent designs, half letter width spacing has become accepted without validation. COMPlog is a computerised visual acuity measurement device being...

article

Inattentional blindness with the same scene at different scales

Henry L. Apfelbaum, Christina Gambacorta, Russell L. Woods, Eli Peli

Ophthalmic and Physiological Optics > 30 > 2 > 124 - 131

People with severely restricted peripheral visual fields have difficulty walking confidently and safely in the physical environment. Augmented vision devices that we are developing for low‐vision rehabilitation implement vision multiplexing, providing two views of the same scene at two different scales (sizes), with a cartooned minified wide view overlaying a natural see‐through view. Inattentional...

article

pH dependent spectral properties of sodium fluorescein ophthalmic solutions revisited

Michael J. Doughty

Ophthalmic and Physiological Optics > 30 > 2 > 167 - 174

Purpose: To re‐assess and further quantify the pH‐related changes in the absorbance and fluorescence emission spectra of sodium fluorescein in buffered aqueous solutions. Methods: Analytical grade sodium fluorescein (NaF) or commercial NaF ophthalmic products (Minims^® 2% sodium fluorescein or Fluorets^® sodium fluorescein ophthalmic strips) were prepared over a range of dilutions in 1% NaCl with...

article

Contact lens material characteristics associated with hydrogel lens dehydration

Padmapriya Ramamoorthy, Loraine T. Sinnott, Jason J. Nichols

Ophthalmic and Physiological Optics > 30 > 2 > 160 - 166

Purpose: To determine the association between material dehydration and hydrogel contact lens material characteristics, including water content and ionicity. Methods: Water content and refractive index data were derived from automated refractometry measurements of worn hydrogel contact lenses of 318 participants in the Contact Lens and Dry Eye Study (CLADES). Dehydration was determined in two ways;...

article

Transient cardiac ischaemia and abnormal variations in systemic blood pressure in unselected primary open angle glaucoma patients

Doina Gherghel, Sarah Louise Hosking, Ian Andrew Cunliffe, Rebekka Heitmar

Ophthalmic and Physiological Optics > 30 > 2 > 175 - 181

Purpose: To investigate the relationship between the occurrence of transient cardiac ischaemic episodes and variations in the ambulatory 24‐h blood pressure and heart rate measurements in a group of unselected glaucoma patients. Design: Prospective study. Participants: Twenty‐four consecutive glaucoma patients and 23 age‐matched controls were included in the present study. Methods: The participants...

article

Evaluation of the performance of accommodating IOLs using a paraxial optics analysis

Jit Ale, Fabrice Manns, Arthur Ho

Ophthalmic and Physiological Optics > 30 > 2 > 132 - 142

Purpose: We employed an analytical approach to evaluate the key parameters for the potential design optimisation of accommodating intra‐ocular lenses (AIOL) and to use these parameters to predict their accommodative performance. Methods: Paraxial thin‐lens equations to predict the accommodative performances of single‐element (1E) and two‐element (2E) AIOLs were developed. 2E‐AIOLs with either mobile...

article

Visual axes in eyes that may be astigmatic and have decentred elements

W. F. Harris

Ophthalmic and Physiological Optics > 30 > 2 > 204 - 207

The visual axis of the eye has been defined in terms of nodal points. However, astigmatic systems usually do not have nodal points. The purpose of this note is to offer a modified definition of visual axes that is in terms of nodal rays instead of nodal points and to show how to locate them from knowledge of the structure of the eye. A pair of visual axes (internal and external) is defined for each...

article

Differences between naïve and expert observers’ vergence and accommodative responses to a range of targets

Anna M Horwood, Patricia M Riddell

Ophthalmic and Physiological Optics > 30 > 2 > 152 - 159

Purpose: Vergence and accommodation studies often use adult participants with experience of vision science. Reports of infant and clinical responses are generally more variable and of lower gain, with the implication that differences lie in immaturity or sub‐optimal clinical characteristics but expert/naïve differences are rarely considered or quantified. Methods: Sixteen undergraduates, naïve to...

article

The Health and Social Security Act 1984 and the price of spectacles among corporate practices in the United Kingdom (1980–2007): a review

Richard Calver

Ophthalmic and Physiological Optics > 30 > 2 > 113 - 123

The Health and Social Security Act 1984 deregulated certain aspects of optometry in the United Kingdom, including advertising and the supply of spectacles, in the hope that greater competition would reduce spectacle prices. The effects of this legislation are tested by plotting the mean prices of private spectacles purchased from corporate optometric practices, from 1980 to 2007. Historical evidence...

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Keywords

COLOUR VISION (10)
ACCOMMODATION (7)
GLAUCOMA (4)
SPECTACLES (4)
COLOR VISION (3)
CONTRAST (3)
MYOPIA (3)
UNIQUE HUES (3)
ADAPTATION (2)
BINOCULAR VISION (2)
CHILDREN (2)
CHROMATIC VISUAL EVOKED POTENTIALS (2)
COLOUR APPEARANCE (2)
COLOUR RENDERING (2)
COLOUR VISION DEFICIENCY (2)
CONTACT LENS (2)
CONTACT LENSES (2)
CONTRAST SENSITIVITY (2)
EYE MOVEMENTS (2)
EYEGLASSES (2)
GLARE (2)
INTRAOCULAR PRESSURE (2)
IOPEN® (2)
KERATOMETRY (2)
LOW VISION (2)
MACULAR PIGMENT (2)
MULTIDIMENSIONAL SCALING (2)
NODAL POINTS (2)
OPTOMETRY (2)
PRESBYOPIA (2)
PRESCRIBING (2)
READING (2)
REBOUND TONOMETER (2)
RODS (2)
SPECTRAL SENSITIVITY (2)
STEREOACUITY (2)
STEREOPSIS (2)
SUBJECTIVE REFRACTION (2)
SURVEY (2)
TEAR FILM (2)
TOPOGRAPHY (2)
(IOP) (1)
ABSORBANCE (1)
ACCEPTABILITY (1)
ACCESS (1)
ACCOMMODATING INTRAOCULAR LENS (1)
ACCOMMODATIVE‐VERGENCE CONFLICT (1)
ACCOMMODATIVE‐VERGENCE CROSS‐LINK (1)
ACQUIRED COLOUR DEFICIENCY (1)
ACTIVITIES OF DAILY LIVING (1)
ADAPTIVE GAIT (1)
ADVERSE REACTION (1)
AGE (1)
AGEING (1)
AGE‐RELATED MACULAR DEGENERATION (AMD) (1)
AGING (1)
AMETROPIA (1)
ANAESTHETIC (1)
ANGLE ALPHA (1)
ANISOTROPY (1)
ANOMALOUS TRICHROMACY (1)
ANOMALOUS TRICHROMATISM (1)
AO HRR TEST (1)
APPARENT NUMEROSITY (1)
APPLANATION TONOMETRY (1)
APPROXIMATE OPTICAL CENTRE (1)
ASTIGMATIC EYE (1)
ASTIGMATISM (1)
ATTENTION (1)
AUGMENTED VISION (1)
AUTOREFRACTION (1)
BIAXIAL (1)
BIOMECHANICS (1)
BIREFRINGENCE (1)
BLINK (1)
BLOOD FLOW (1)
BLOOD PRESSURE (1)
BLUE‐YELLOW CHANNEL (1)
BLUR (1)
BRIGHTNESS (1)
BUTTERFLIES (1)
CAMBRIDGE COLOUR TEST (1)
CAPILLARY LEAKAGE (1)
CARDIAC ISCHAEMIA (1)
CASE‐FINDING (1)
CATEGORY SCALING (1)
CAT‐EYE (1)
CCCTC‐BINDING FACTOR (1)
CFF (1)
CHOROIDEREMIA (1)
CHROMATIC ADAPTATION (1)
CHROMATIC DETECTION (1)
CHROMATIC EFFECTS (1)
CHROMATIC ILLUMINATION (1)
CHROMATIC MECHANISM (1)
CHROMATIC MOTION (1)
CHROMATIC SENSITIVITY (1)
CLINICAL PRACTICE (1)
CLINICAL VIGNETTE (1)
COEFFICIENT OF RETROREFLECTION (1)
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Ophthalmic and Physiological Optics

Investigation of the causes of non‐tolerance to optometric prescriptions for spectacles

Discriminate characteristics of photopsia in posterior vitreous detachment, retinal tears and retinal detachment

Nodes and nodal points and lines in eyes and other optical systems

Animal‐eyeball vs. road‐sign retroreflectors

Discriminating colors through a red filter by protanopes and colour normals

Quantification of heterophoria and phoria adaptation using an automated objective system compared to clinical methods

Effect of chromatic mechanisms on the detection of mesopic incremental targets at different eccentricities

Do multipurpose contact lens disinfecting solutions work effectively against non‐FDA/ISO recommended strains of bacteria and fungi?

Reconstructing ocular surfaces by Purkinje images using an exact ray approach: estimating IOL decenter and tilt

Comparison of the IOPen^® and iCare^® rebound tonometers with the Goldmann tonometer in a normal population

Assessing visual activities of daily living in the visually impaired

Effect of letter separation on computerised visual acuity measurements: comparison with the gold standard Early Treatment Diabetic Retinopathy Study (ETDRS) chart

Inattentional blindness with the same scene at different scales

pH dependent spectral properties of sodium fluorescein ophthalmic solutions revisited

Contact lens material characteristics associated with hydrogel lens dehydration

Transient cardiac ischaemia and abnormal variations in systemic blood pressure in unselected primary open angle glaucoma patients

Evaluation of the performance of accommodating IOLs using a paraxial optics analysis

Visual axes in eyes that may be astigmatic and have decentred elements

Differences between naïve and expert observers’ vergence and accommodative responses to a range of targets

The Health and Social Security Act 1984 and the price of spectacles among corporate practices in the United Kingdom (1980–2007): a review

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