Does the Swedish Interactive Threshold Algorithm (SITA) accurately map visual field loss attributed to vigabatrin?

Background: Vigabatrin (VGB) is an anti-epileptic medication which has been linked to peripheral constriction of the visual field. Documenting the natural history associated with continued VGB exposure is important when making decisions about the risk and benefits associated with the treatment. Due to its speed the Swedish Interactive Threshold Algorithm (SITA) has become the algorithm of choice when carrying out Full Threshold automated static perimetry.

Provocative intraocular pressure challenge preferentially decreases venous oxygen saturation despite no reduction in blood flow.

Purpose: Ocular disease can both alter the retina's oxygen requirements, and decrease its ability to cope with changes in metabolic demand. We examined the influence of a moderate intraocular pressure (IOP) elevation on three outcome measures: arterial and venous oxygen saturation, blood flow, and the pattern electroretinogram (PERG).

Methods: We increased IOP to ˜30 mmHg in 23 healthy participants (22-39 years) using a mechanical probe applied to the eyelid, thereby lowering ocular perfusion pressure (OPP) by ~30%.

Test-retest reliability of retinal oxygen saturation measurement.

Purpose: To determine intrasession and intersession repeatability of retinal vessel oxygen saturation from the Oxymap Retinal Oximeter using a whole image-based analysis technique and so determine optimal analysis parameters to reduce variability.

Methods: Ten fundus oximetry images were acquired through dilated pupils from 18 healthy participants (aged 22 to 38) using the Oxymap Retinal Oximeter T1. A further 10 images were obtained 1 to 2 weeks later from each individual.

Retinal oxygen saturation: novel analysis method for the oxymap.

Purpose: To use a novel image analysis approach to consider how oxygen saturation changes as a function of vessel width and distance from the nerve and between superior and inferior retinal hemifields.

Methods: Ten images were acquired from one eye of 17 participants (mean [standard deviation] age, 28 [4] years; range, 22-38 years) using the Oxymap T1 retinal oximeter. Every pixel identified by the detection algorithm was extracted, and frequency histograms of retinal vessel oxygen saturation were plotted for each vessel diameter (70-170 μm).

Short-term stability in refractive status despite large fluctuations in glucose levels in diabetes mellitus type 1 and 2.

Purpose: This work investigates how short-term changes in blood glucose concentration affect the refractive components of the diabetic eye in patients with long-term Type 1 and Type 2 diabetes.

Methods: Blood glucose concentration, refractive error components (mean spherical equivalent MSE, J0, J45), central corneal thickness (CCT), anterior chamber depth (ACD), crystalline lens thickness (LT), axial length (AL) and ocular aberrations were monitored at two-hourly intervals over a 12-hour period in: 20 T1DM patients (mean age ± SD) 38±14 years, baseline HbA1c 8.6±1.

Investigation of ocular hemodynamics in Sturge-Weber syndrome.

Purpose: Sturge-Weber syndrome (SWS) is a condition often associated with facial cutaneous angioma, vascular malformations in the brain, and ocular anomalies such as glaucoma. Reduced cerebral blood flow and ischemia have been well documented. Less is known about ocular blood flow despite the frequent associations between altered hemodynamics and the mechanisms underlying glaucomatous optic neuropathy.

Reproducibility-repeatability of choroidal thickness calculation using optical coherence tomography.

Purpose: To evaluate the repeatability and reproducibility of subfoveal choroidal thickness (CT) calculations performed manually using optical coherence tomography (OCT).

Methods: The CT was imaged in vivo at each of two visits on 11 healthy volunteers (mean age, 35.72 ± 13.

Ocular blood flow measurements in healthy human myopic eyes.

Background: To evaluate the haemodynamic features of young healthy myopes and emmetropes, in order to ascertain the perfusion profile of human myopia and its relationship with axial length prior to reaching a degenerative state.

Methods: The retrobulbar, microretinal and pulsatile ocular blood flow (POBF) of one eye of each of twenty-two high myopes (N = 22, mean spherical equivalent (MSE) ≤-5.00D), low myopes (N = 22, MSE-1.

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

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.

Ocular blood-flow hemodynamics before and after application of a laser in situ keratomileusis ring.

Purpose: To evaluate blood-flow responses before and after microkeratome application.

Setting: School of Life and Health Sciences, Aston University, Birmingham, United Kingdom.

Methods: Hemodynamic responses were measured in eyes of healthy volunteers before and after transient elevation in intraocular pressure (IOP) resulting from microkeratome application.

Oxygenation state and mesopic sensitivity to dynamic contrast stimuli.

Purpose: Comparative studies suggest that increasing photoreceptor oxygen consumption in dim light, relative to bright light, may make the outer retina susceptible to hypoxia at light levels relevant to aviation at night. Accordingly, this study investigates effects of relevant oxygenation states on sensitivity to a dynamic contrast stimulus at low photopic and mesopic light levels experienced during night flying.

Methods: Threshold sensitivity to frequency-doubled contrast stimuli was assessed under mild hypoxia (breathing 14.

A pilot study on the differences in wavefront aberrations between two ethnic groups of young generally myopic subjects.

A comparative population-based cross-sectional study design was used to examine the prevalence of wavefront patterns in two different ethnic groups, and the relationship of these patterns with ocular biometrics and gender. The Shin-Nippon SRW5000 open field autorefractor, the Wavefront Analysis Supported Customized Ablation (WASCA) wavefront analyser and the IOLMaster were used to determine wavefront aberrations, mean spherical equivalent (SE) refractive error and axial length (AL). Seventy-four eyes from 74 young healthy subjects (44 British Asians, 30 Caucasians; 36 men, 38 women; mean age 22.

Comparison of higher order aberrations measured by NIDEK OPD-Scan dynamic skiascopy and Zeiss WASCA Hartmann-Shack aberrometers.

Purpose: To compare the measurement of wavefront aberrations in non-cyclopleged human eyes with Hartmann-Shack and dynamic skiascopy wavefront analyzers.

Methods: Eighty eyes of 40 healthy young adults (19 men, 21 women; mean age 20.8 +/- 2.

Objective measurement of intraocular forward light scatter using Hartmann-Shack spot patterns from clinical aberrometers. Model-eye and human-eye study.

Purpose: To apply software-based image-analysis tools to objectively determine intraocular scatter determined from clinically derived Hartmann-Shack patterns.

Setting: Aston Academy of Life Sciences, Aston University, Birmingham, United Kingdom, and Department of Optics, University of Valencia, Valencia, Spain.

Methods: Purpose-designed image-analysis software was used to quantify scatter from centroid patterns obtained using a clinical Hartmann-Shack analyzer (WASCA, Zeiss/Meditec).

Effect of sport-tinted contact lenses for contrast enhancement on retinal straylight measurements.

Purpose: To investigate the effect of two tinted contact lenses (CL) designed for outdoor sports activity on the psychometric determination of retinal straylight using the compensation comparison method.

Methods: Thirteen emmetropic subjects were randomly fitted with two different tinted Nike Maxsight (Bausch & Lomb, Rochester, NY, USA) CL in one eye, while the contralateral eye was fitted with a clear lens made of the same material (Optima 38, Bausch & Lomb). Three valid straylight measurements were taken on each eye before and a few minutes after lens insertion, when lens stabilization had occurred.

Retinal straylight in patients with monofocal and multifocal intraocular lenses.

Purpose: To determine the differences in retinal straylight perceived by patients with monofocal intraocular lenses (IOLs) and patients with multifocal IOLs.

Setting: Vissum-Instituto de Oftalmológico de Alicante, Alicante, Spain.

Methods: In this prospective study, contrast sensitivity and retinal straylight were measured prospectively 6 months postoperatively in 67 eyes of 40 patients with a monofocal or multifocal IOL.

Mild hypoxia impairs chromatic sensitivity in the mesopic range.

Purpose: The effect of mild hypoxia on chromatic sensitivity in the mesopic range is poorly documented. This study was conducted to examine the effects of mild hypoxia and hyperoxia on red-green (R-G) and yellow-blue (Y-B) chromatic sensitivity thresholds at low photopic (22.3 cd .

Visual field severity indices demonstrate dose-dependent visual loss from vigabatrin therapy.

Purpose: The aims of this study were to develop an algorithm to accurately quantify Vigabatrin (VGB)-induced central visual field loss and to investigate the relationship between visual field loss and maximum daily dose, cumulative dose and duration of dose.

Methods: The sample comprised 31 patients (mean age 37.9 years; SD 14.

Oxygenation and gender effects on photopic frequency-doubled contrast sensitivity.

Thresholds to a temporally modulated contrast stimulus were examined across the central visual field, at photopic luminance (100 cd m(-2)), under aviation-related respiratory disturbances. These were mild hypoxia (14.1% oxygen), hyperoxia (100% oxygen), and hypocapnia (voluntary hyperventilation), with control exposures breathing air at rest.

Clinical ocular wavefront analyzers.

Purpose: To provide a summary of the methods used by clinical wavefront analyzers and their historical, current, and future applications.

Methods: Review of the literature and authors' experience with the various devices.

Results: A wide range of clinical wavefront aberrometers, which use different principles, are available to clinicians and researchers.

Autonomic dysfunction in unselected and untreated primary open angle glaucoma patients: a pilot study.

Purpose: To investigate the presence of silent cardiac ischaemic episodes and the status of autonomic function in consecutive, newly diagnosed and untreated primary open-angle glaucoma patients.

Methods: Twenty-four consecutively diagnosed glaucoma patients and 22 age-matched controls were subjected to ambulatory 24-h blood pressure (BP) and electrocardiogram (ECG) monitoring by using Cardiotens-01 (Meditech Ltd). Based on the ECG recordings, heart rate variability (HRV) frequency domain parameters [low-frequency (LF), high-frequency (HF) and LF/HF ratio] were calculated and analysed in the two study groups.

Regression analysis of ranked segment parameters for optic nerve head classification: a pilot study.

Purpose: To determine whether curve-fitting analysis of the ranked segment distributions of topographic optic nerve head (ONH) parameters, derived using the Heidelberg Retina Tomograph (HRT), provide a more effective statistical descriptor to differentiate the normal from the glaucomatous ONH.

Methods: The sample comprised of 22 normal control subjects (mean age 66.9 years; S.

Operator-induced errors in Hartmann-Shack wavefront sensing: model eye study.

Purpose: To evaluate the effects of instrument realignment and angular misalignment during the clinical determination of wavefront aberrations by simulation in model eyes.

Setting: Aston Academy of Life Sciences, Aston University, Birmingham, United Kingdom.

Methods: Six model eyes were examined with wavefront-aberration-supported cornea ablation (WASCA) (Carl Zeiss Meditec) in 4 sessions of 10 measurements each: sessions 1 and 2, consecutive repeated measures without realignment; session 3, realignment of the instrument between readings; session 4, measurements without realignment but with the model eye shifted 6 degrees angularly.

Wavefront analyzers induce instrument myopia.

Purpose: To assess the accuracy of three wavefront analyzers versus a validated binocular open-view autorefractor in determining refractive error in non-cycloplegic eyes.

Methods: Eighty eyes were examined using the SRW-5000 open-view infrared autorefractor and, in randomized sequence, three wavefront analyzers: 1) OPD-Scan (NIDEK, Gamagori, Japan), 2) WASCA (Zeiss/Meditec, Jena, Germany), and 3) Allegretto (WaveLight Laser Technologies AG, Erlangen, Germany). Subjects were healthy adults (19 men and 21 women; mean age: 20.