Validation of the Iowa Head-Mounted Open-Source Perimeter.

Purpose: To assess the validity of visual field (VF) results from the Iowa Head-Mounted Display (HMD) Open-Source Perimeter and to test the hypothesis that VF defects and test-retest repeatability are similar between the HMD and Octopus 900 perimeters. Methods: We tested 20 healthy and nine glaucoma patients on the HMD and Octopus 900 perimeters using the Open Perimetry Interface platform with size V stimuli, a custom grid spanning the central 26° of the VF, and a ZEST thresholding algorithm. Historical data from the Humphrey Field Analyzer (HFA) were also analyzed. Repeatability was analyzed with the repeatability coefficient (RC), and VF defect detection was determined through side-by-side comparisons. Results: The pointwise RCs were 2.6 dB and 3.4 dB for the HMD and Octopus 900 perimeters in ocular healthy subjects, respectively. Likewise, the RCs were 4.2 dB and 3.5 dB, respectively, in glaucomatous patients. Limits of agreement between the HMD and Octopus 900 perimeters were ±4.6 dB (mean difference, 0.4 dB) for healthy patients and ±8.9 dB (mean difference, 0.1 dB) for glaucomatous patients. Retrospective analysis showed that pointwise RCs on the HFA2 perimeter were between 3.4 and 3.7 dB for healthy patients and between 3.9 and 4.7 dB for glaucoma patients. VF defects were similar between the HMD and Octopus 900 for glaucoma subjects. Conclusions: The Iowa Virtual Reality HMD Open-Source Perimeter is as repeatable as the Octopus 900 perimeter and is a more portable and less expensive alternative than traditional perimeters. Translational Relevance: This study demonstrates the validity of the visual field results from the Iowa HMD Open-Source Perimeter which may help expand perimetry access.

The Open Perimetry Initiative: A framework for cross-platform development for the new generation of portable perimeters.

The Open Perimetry Initiative was formed in 2010 with the aim of reducing barriers to clinical research with visual fields and perimetry. Our two principal tools are the Open Perimetry Interface (OPI) and the visualFields package with analytical tools. Both are fully open source. The OPI package contains a growing number of drivers for commercially available perimeters, head-mounted devices, and virtual reality headsets. The visualFields package contains tools for the analysis and visualization of visual field data, including methods to compute deviation values and probability maps. We introduce a new frontend, the opiApp, that provides tools for customization for visual field testing and can be used as a frontend to run the OPI. The app can be used on the Octopus 900 (Haag-Streit), the Compass (iCare), the AP 7000 (Kowa), and the IMO (CREWT) perimeters, with permission from the device manufacturers. The app can also be used on Android phones with virtual reality headsets via a new driver interface, the PhoneHMD, implemented on the OPI. The use of the tools provided by the OPI library is showcased with a custom static automated perimetry test for the full visual field (up to 50 degrees nasally and 80 degrees temporally) developed with the OPI driver for the Octopus 900 and using visualFields for statistical analysis. With more than 60 citations in clinical and translational science journals, this initiative has contributed significantly to expand research in perimetry. The continued support of researchers, clinicians, and industry are key in transforming perimetry research into an open science.

Visual Field Progression in Glaucoma: Comparison Between PoPLR and ANSWERS.

Purpose: It has been suggested that the detection of visual field progression can be improved by modeling statistical properties of the data such as the increasing retest variability and the spatial correlation among visual field locations. We compared a method that models those properties, Analysis with Non-Stationary Weibull Error Regression and Spatial Enhancement (ANSWERS), against a simpler one that does not, Permutation of Pointwise Linear Regression (PoPLR). Methods: Visual field series from three independent longitudinal studies in patients with glaucoma were used to compare the positive rate of PoPLR and ANSWERS. To estimate the false-positive rate, the same visual field series were randomly re-ordered in time. The first dataset consisted of series of 7 visual fields from 101 eyes, the second consisted of series of 9 visual fields from 150 eyes, and the third consisted of series of more than 9 visual fields (17.5 on average) from 139 eyes. Results: For a statistical significance of 0.05, the false-positive rates for ANSWERS were about 3 times greater than expected at 15%, 17%, and 16%, respectively, whereas for PoPLR they were 7%, 3%, and 6%. After equating the specificities at 0.05 for both models, positive rates for ANSWERS were 16%, 25%, and 38%, whereas for PoPLR they were 12%, 33%, and 49%, or about 5% greater on average (95% confidence interval = -1% to 11%). Conclusions: Despite being simpler and less computationally demanding, PoPLR was at least as sensitive to deterioration as ANSWERS once the specificities were equated. Translational Relevance: Close control of false-positive rates is key when visual fields of patients are analyzed for change in both clinical practice and clinical trials.

Objective changes in astigmatism during accommodation.

PURPOSE: Previous studies have shown small but clinically significant changes in the power and axis of astigmatism when the eye accommodates. Monocular objective measurements of the eye during accommodation, when the object approaches the eye without convergence, also reveal small astigmatic changes. Moreover, it is known that the eye exhibits ocular cyclotorsion at different gaze angles. Since accommodation and convergence normally occur simultaneously, we studied the change in the magnitude and axis of astigmatism during accommodation for different convergence angles. METHODS: The left eye of 15 subjects between 20 and 49 years old (mean 28.5 ± 9.7 years) having ≤1.5 D astigmatism was evaluated. Measurements were made using a Shack-Hartmann aberrometer for an accommodation range of +0.50 D to -10 D in 0.50 D steps, and for four monocular convergence demands: 0°, 5°, 10° and 15°. Statistical analysis used power vectors to quantify the change in cylinder power and axis for each accommodation and convergence demand with age. RESULTS: Jackson cross-cylinder component J45 did not change during accommodation for all vergences tested. However, J0 changed by an average of -0.02 D per dioptre of accommodation (D/Dacc) for convergence demands of 0°, 5° and 10° and -0.03 D/Dacc for the 15° demand. This corresponds to an average cylinder power change of -0.05 D/Dacc for convergences of 0°, 5° and 10° and -0.08 D/Dacc for 15° of convergence. The cylinder axis always changed towards 90° (against-the-rule), and age did not play a significant role. CONCLUSIONS: Except for accommodation demands >4 D, we did not find a clinically significant change in astigmatism for convergence angles up to 15º. The small changes in cylinder power and axis may be due to shifts in the position of the crystalline lens during accommodation.

Predictability of sinusoidally moving stimuli does not improve the accuracy of the accommodative response.

Previous research work suggests that predictable target motion such as sinusoidal movement can be anticipated by the visual system, thereby improving the accommodative response. The validity of predictable motion for studying human dynamic accommodation is sometimes put into question. The aim of this work was to assess the effect of anticipation along with learning (and motivation, etc.) and fatigue (and boredom, loss of attention, etc.) on dynamic accommodation experiments from a practical perspective. Specifically, changes in amplitude and temporal phase lag were estimated within and between trials as 9 adult observers were instructed to focus on a stimulus that oscillated sinusoidally towards and away from the eye at specific temporal frequencies. On average, amplitude decreased whereas phase increased within trials. No evidence of anticipation or learning was observed either within or between trials. Fatigue consistently dominated anticipation and learning within the course of each trial. Even if the eye is equipped by a prediction operator as it is often assumed, fatigue confounds the results from dynamic accommodation experiments more than anticipation or learning.

Detecting Progression in Patients With Different Clinical Presentations of Primary Open-angle Glaucoma.

PRCIS: Glaucoma progression was more frequently identified by assessing retinal fiber layer thickness than by monitoring visual field (VF) loss for different baseline classifications in primary open-angle glaucoma. PURPOSE: The aim was to compare the detection of glaucoma progression by retinal nerve fiber layer thickness (RNFLT) and VF assessments for different baseline classifications of primary open-angle glaucoma. METHODS: This study included 194 eyes from 194 patients with a minimum of 9 follow-up visits selected from the Diagnostic Innovation in Glaucoma Study (DIGS) and the African Descent and Glaucoma Evaluation Study (ADAGES). Each eye was classified according to baseline clinical signs: ocular hypertension (n=39), glaucomatous optic neuropathy only (n=60), glaucomatous visual field loss only (GVF, n=39) and definite glaucoma (concurrent optic disc and VF defect, n=56). We assessed progression by performing simple linear regression on global and sectorial mean deviations values generated for RNFLT (RNFLT-MD) and VF data (VF-MD). The proportion of eyes identified as progressing (positive rate) by RNFLT-MD and by VF-MD were compared within each classification. RESULTS: Whereas both parameters performed similarly among glaucomatous optic neuropathy only and definite glaucoma eyes, the positive rate obtained with global RNFLT-MD was significantly greater compared with global VF-MD by 33.3% and 30.8% among ocular hypertension eyes and GVF eyes, respectively. This finding was consistent in the inferotemporal sector; however, similar positive rates were obtained for both parameters in the superotemporal sector. CONCLUSIONS: While both RNFLT and VF parameters showed comparable abilities to identify progression across the different classifications, RNFLT assessment may be better suited to monitor progression, particularly among patients with elevated intraocular pressure and those who present with only GVF defect at baseline.

The Effect of Retinal Illuminance on the Subjective Amplitude of Accommodation.

SIGNIFICANCE: We show that the amplitude of accommodation decreases with retinal illumination even under photopic reading conditions and a constant pupil size. This result provides a basis for clinical approaches that are not based on an optical explanation. PURPOSE: We investigated the effect of retinal illuminance on the amplitude of accommodation while the pupil of the eye remained constant. METHODS: The amplitudes of accommodation of 10 young subjects (from 20 to 38 years of age) and that of 10 presbyopic subjects (from 45 to 54 years of age) were measured subjectively through an artificial pupil of 5 mm using a Badal optometer and for four values of retinal illuminance: 222, 821, 2138, and 5074 trolands. Phenylephrine was instilled to all the subjects to ensure that their natural pupil was greater than the artificial one in all experimental runs. Linear mixed-effects model for repeated measures with age and log luminance as covariates were used to check whether changes in amplitude of accommodation with retinal illumination were statistically significant. RESULTS: In the range of illuminances tested, the amplitude of accommodation decreased on average from 6.34 to 4.35 D in the young subjects and from 1.69 to 1.04 D in the presbyopic subjects. Illuminance was associated with the amplitude of accommodation in both young and presbyopic groups, with P < .01. CONCLUSIONS: The reduction in the amplitude of accommodation with target illumination (a phenomenon named night presbyopia) under photopic light conditions is not only due to a reduction in the depth of focus as a consequence of pupil dilation; it is strongly affected by the decrease of retinal illumination.

A framework for assessing glaucoma progression using structural and functional indices jointly.

PURPOSE: While many tests and indices are available to identify glaucoma progression, using them in combinations may decrease overall specificity. The aim of this study was to develop a framework for assessing glaucoma progression using structural and functional indices jointly for a fixed specificity. METHODS: The study included 337 eyes of 207 patients with ocular hypertension or primary open-angle glaucoma selected from the Diagnostic Innovations in Glaucoma Study or the African Descent and Glaucoma Evaluation Study. All patients had at least 9 visits. Each visit had retinal nerve fiber layer thickness (RNFLT) and mean sensitivity from static automated perimetry (SAP MS) measured within a one-month window. Simple linear regression was applied to assess deterioration in each index for series of 5 to 9 visits. To identify progression using the two indices jointly, marginal significance levels set at a specificity of 95% were derived for two criteria: ANY (worsening on either RNFLT or SAP MS) and ALL (worsening on both RNFLT and SAP MS). Positive rate (percentage of eyes flagged as progressing) was determined individually for each index, as well as for the ANY and ALL criteria. RESULTS: Compared to SAP MS, RNFLT had higher positive rates (15% to 45%) for all series lengths. For the joint analyses, the positive rate was on average 12% higher for the ANY criterion compared to the ALL criterion. While RNFLT-alone had comparable positive rates and time-to-detection as the ANY criterion, each uniquely identified a subset of eyes (Kappa = 0.55 to 0.75). CONCLUSIONS: This study provides a simple framework for assessing glaucoma progression with data from two tests jointly, without compromising specificity. This framework can be extended to include two or more parameters, can accommodate global or regional indices, and can eventually be used with novel parameters identified as predictive of glaucoma progression.

Threshold Automated Perimetry of the Full Visual Field in Patients With Glaucoma With Mild Visual Loss.

PRECIS: The authors used the Open Perimetry Interface to design a static automated perimetry test of the full field. Abnormal test locations in the nasal midperiphery and temporal inferior sector area best separated glaucomas from normals. PURPOSE: The peripheral visual field in glaucoma outside 30 degrees is largely unexplored with static perimetry. Their goal was to use threshold static automated perimetry to characterize the visual loss in glaucoma of the central 30 degrees and the far periphery. PATIENTS AND METHODS: The authors administered the 30-2 perimetric test to 27 patients with early stage glaucoma (with mean deviation better than -4 dB) with the Goldmann III and V stimulus sizes and a custom test from 30 to up to 87 degrees with the size V stimulus twice within a month. The authors quantified (1) the retest variability, (2) the proportion of patients flagged as abnormal (at level 0.05) on the basis of pointwise probability distributions obtained from 63 ocular healthy observers, (3) the pointwise statistical distance using the Kullback-Leibler divergence between normal and glaucoma eyes, and (4) the effect of eccentricity on visual loss. RESULTS: Size V 30-2 testing identified significantly more abnormal test locations (36%) than size III 30-2 (30%; P=0.004). Kullback-Leibler divergence between healthy and glaucoma distributions was greatest for the nasal midperipheral test locations and the inferior temporal sector area. A more pronounced decrease was found in visual sensitivity with eccentricity in the patients with glaucoma compared with the ocular healthy participants across the full visual field (P<0.001). CONCLUSIONS: Patients with glaucoma demonstrate a systematic decrease in sensitivity with eccentricity across the full visual field. Goldmann size V stimuli better detected visual loss in patients with glaucoma with mild loss than size III.

Threshold Static Automated Perimetry of the Full Visual Field in Idiopathic Intracranial Hypertension.

Purpose: To characterize visual loss across the full visual field in idiopathic intracranial hypertension (IIH) patients with mild central visual loss. Methods: We tested the full visual field (50° nasal, 80° temporal, 30° superior, 45° inferior) of 1 eye of 39 IIH patients by using static perimetry (size V) with the Open Perimetry Interface. Participants met the Dandy criteria for IIH and had at least Frisén grade 1 papilledema with better than -5 dB mean deviation (MD) centrally. Two observers (MW and AS) evaluated the visual field defects, adjudicated any differences, and reviewed optical coherence tomography data. Results: We found a greater MD loss peripherally than centrally (central 26°). The median MD (and corresponding median absolute deviations) was -1.37 dB (1.61 dB) for the periphery and -0.77 dB (0.87 dB) for the central 26°, P < 0.001. There were about 30% more abnormal test locations identified in the periphery (P = 0.12), and the mean defect depth increased with eccentricity (P < 0.001). The most frequent defect found was a temporal wedge (23% of cases) in the periphery with another 23% that included this sector with inferior temporal loss. Although the presence of papilledema limited correlation, 55% of the temporal wedge defects had optical coherence tomography retinal nerve fiber layer deficits in the corresponding superonasal location. Other common visual field defects were inferonasal loss, superonasal loss, and superior and inferior arcuate defects. Seven patients (18%) had visual field defects in the periphery with normal central visual field testing. Conclusion: In IIH patients, we found substantial visual loss both outside 30° of the visual field and inside 30° with the depth of the defect increasing linearly with eccentricity. Temporal wedge defects were the most common visual field defect in the periphery. Static threshold perimetry of the full visual field appears to be clinically useful in IIH patients.

Defocus vibrations in optical systems-considerations in reference to the human eye.

Experimental visual acuity (VA) of eight subjects was measured using the Freiburg vision test in a custom-made adaptive optics system. Measurements were conducted under one control and five defocus-induced conditions. In the defocus-induced conditions, 1 diopter of myopic defocus was added to the system using the Badal stage, and defocus vibrations with five different levels of amplitude were generated by a deformable mirror at 50 Hz. Computational simulations of the visual Strehl ratio (VSOTF) were performed using average aberrations of each subject recorded in the control condition. For the first time, to the best of our knowledge, it has been shown experimentally that both the simulated VSOTF and experimentally measured VA improve when defocus vibrations are added to a defocused eye.

Effect of phenylephrine on static and dynamic accommodation / Efecto de la fenilefrina sobre la acomodación estática y dinámica

Purpose: We tested the hypothesis that changes in accommodation after instillation of Phenylephrine Hydrochloride (PHCl) observed in some studies could be caused by changes in optics. Methods: We performed two experiments to test the effects of PHCl on static and on dynamic accommodation in 8 and 6 subjects, respectively. Objective wavefront measurements were recorded of the static accommodation response to a stimulus at different distances or dynamic accommodation response to a sinusoidally moving stimulus (between 1 and 3 D of accommodative demand at 0.2 Hz). The responses were characterized using two methods: one that takes into account the mydriatic optical effects on the accommodation produced by higher-order aberrations of the eye and another that takes into account only power changes paraxially due to the action of the ciliary muscle and regardless of the pupil size. Results: When mydriatic optical effects were taken into account, differences in responses before and after PHCl instillation were 0.51 ± 0.53 D, and 0.12 ± 0.15, for static and dynamic accommodation, respectively, and were statistically significant (p < 0.039). When mydriatic optical effects were not taken into account, the differences in responses before and after PHCl instillation were -0.20 ± 0.51 D, and -0.05 ± 0.14, for static and dynamic accommodation, respectively, and were not statistically significant (p > 0.313). Conclusions: The mydriatic effect of the PHCl causes optical changes in the eye that can reduce the objective and subjective measurement of accommodation

Objetivo: Probamos la hipótesis de que los cambios de la acomodación tras la instilación de Hidrocloruro de Fenilefrina (PHCl) observados en algunos estudios podrían estar originados por los cambios en la óptica. Métodos: Realizamos dos experimentos para probar los efectos de PHCl sobre la acomodación estática y dinámica en 8 y 6 sujetos, respectivamente. Se registraron las mediciones objetivas de frente de onda de la respuesta acomodativa estática a un estímulo a diferentes distancias, o la respuesta acomodativa dinámica a un estímulo con movimiento sinusoidal (entre 1 y 3 D de demanda acomodativa a 0,2Hz). Las respuestas se caracterizaron utilizando dos métodos: uno que tiene en cuenta los efectos ópticos midriáticos sobre la acomodación producida por aberraciones de alto orden, y otro que considera únicamente los cambios de potencia paraxialmente, debido a la acción del músculo ciliar, independientemente del tamaño de la pupila. Resultados: Al tenerse en cuenta los efectos ópticos midriáticos, las diferencias de las respuestas antes y después de la instilación de PHCl fueron de 0,51 ± 0,53 D, y 0,12 ± 0,15, para la acomodación estática y dinámica, respectivamente, siendo estadísticamente significativas (p < 0,039). Al no considerarse los efectos ópticos midriáticos, las diferencias en cuanto a las respuestas antes y después de la instilación de PHCl fueron de -0,2 ± 0,51 D, y -0,05 ± 0,14, para la acomodación estática y dinámica, respectivamente, no siendo estadísticamente significativas (p > 0,313). Conclusiones: El efecto midriático de PHCl origina cambios ópticos en el ojo que pueden reducir la medición objetiva y subjetiva de la acomodación

Effect of phenylephrine on static and dynamic accommodation.

PURPOSE: We tested the hypothesis that changes in accommodation after instillation of Phenylephrine Hydrochloride (PHCl) observed in some studies could be caused by changes in optics. METHODS: We performed two experiments to test the effects of PHCl on static and on dynamic accommodation in 8 and 6 subjects, respectively. Objective wavefront measurements were recorded of the static accommodation response to a stimulus at different distances or dynamic accommodation response to a sinusoidally moving stimulus (between 1 and 3 D of accommodative demand at 0.2Hz). The responses were characterized using two methods: one that takes into account the mydriatic optical effects on the accommodation produced by higher-order aberrations of the eye and another that takes into account only power changes paraxially due to the action of the ciliary muscle and regardless of the pupil size. RESULTS: When mydriatic optical effects were taken into account, differences in responses before and after PHCl instillation were 0.51±0.53 D, and 0.12±0.15, for static and dynamic accommodation, respectively, and were statistically significant (p<0.039). When mydriatic optical effects were not taken into account, the differences in responses before and after PHCl instillation were -0.20±0.51 D, and -0.05±0.14, for static and dynamic accommodation, respectively, and were not statistically significant (p>0.313). CONCLUSIONS: The mydriatic effect of the PHCl causes optical changes in the eye that can reduce the objective and subjective measurement of accommodation.

Impact of higher-order aberrations on depth-of-field.

It is well known that depth-of-focus (DOF) is influenced by optical factors (such as pupil size and monochromatic aberrations). However, neural factors such as blur sensitivity and defocus adaptation may play an important role on the extent of DOF. A series of experiments were conducted to study if optical or neural factors are most pertinent in explaining the variability of DOF across subjects. An adaptive optics system with a black and white target, a 3.8-mm artificial pupil, and a subjective criterion (based on objectionable blur) were used to measure depth of field ([DOFi]; DOF computed in the object space) in 11 participants, after at least 6 min of adaptation. This was done under three conditions: (a) with their own higher order aberrations (HOA); (b) after correction of their monochromatic HOA; and (c) after altering the HOA pattern for some participants to reflect the HOA pattern measured for a different participant. Natural DOFi and DOFi after HOA correction were positively correlated (R2 = 0.461), but a significant decrease in DOFi (21% on average) was found after HOA correction (p = 0.042). Effect of HOA on the intersubject variability of DOFi was 3.9 times smaller than the effect of the image neural processing. This study shows that DOFi depends on both optical and neural factors, but the latter seems to play a more important role than the former.

Data obtained with an open-source static automated perimetry test of the full visual field in healthy adults.

The data were gathered from 98 eyes of 98 ocular healthy subjects. The subject ages ranged from 18 to 79 years with a mean (and standard deviation) of 47 (17) years. Each subject underwent two visual field tests, one of the central visual field (64 locations within 26° of fixation) and one of the peripheral visual field (64 locations with eccentricity from 26° to up to 81°). Luminance thresholds for the Goldmann size V stimulus (with a diameter of 1.72° of visual angle) were obtained with the ZEST Bayesian test procedure. Each test was conducted twice within 90 days.

The effect of spherical aberration on visual performance and refractive state for stimuli and tasks typical of night viewing / Efecto de la aberración esférica sobre el rendimiento visual y el estado refractivo para los estímulos y tareas típicos de la visión nocturna

Purpose: The aim of this work was to examine the impact of Seidel spherical aberration (SA) on optimum refractive state for detecting and discriminating small bright lights on a dark background. Methods: An adaptive-optics system was used to correct ocular aberrations of cyclopleged eyes and then systematically introduce five levels of Seidel SA for a 7-mm diameter pupil: 0, ± 0.18, and ± 0.36 diopters (D )mm-2. For each level of SA, subjects were required to detect one or resolve two points of light (0.54 arc min diameter) on a dark background. Refractive error was measured by adjusting stimulus vergence to minimize detection and resolution thresholds. Two other novel focusing tasks for single points of light required maximizing the perceived intensity of a bright point's core and minimizing its overall perceived size (i.e. minimize starburst artifacts). Except for the detection task, luminance of the point of light was 1000 cd m-2 on a black background lower than 0.5 cdm-2. Results: Positive SA introduced myopic shifts relative to the best subjective focus for dark letters on a bright background when there was no SA, whereas negative SA introduced hyperopic shifts in optimal focus. The changes in optimal focus were -1.7, -2.4, -2.0, and -9.2 D of focus per D mm-2 of SA for the detection task, resolution task, and maximization of core's intensity and minimization of size, respectively. Conclusion: Ocular SA can be a significant contributor to changes in refractive state when viewing high-contrast point sources typically encountered in nighttime environments

Objetivo: El objetivo de este estudio fue examinar el impacto de la aberración esférica de Seidel (AS) sobre el estado refractivo óptimo para detectar y discriminar las luces brillantes de pequeño tamaño sobre un fondo oscuro. Métodos: Se utilizó un sistema de óptica adaptativa para corregir las aberraciones oculares de ojos bajo cicloplegía, e introducir sistemáticamente cinco valores de AS para una pupila de 7 mm de diámetro: 0, ± 0,18, y ± 0,36 dioptrías (D) mm-2. Para cada valor de AS se solicitó a los sujetos que detectaran un punto de luz, o resolvieran dos puntos (cada punto subtendía 0,54 minutos de arco de diámetro) sobre un fondo oscuro. El error refractivo se midió ajustando la vergencia del estímulo, para minimizar los umbrales de detección y resolución. Los sujetos realizaron además otras dos tareas observando un sólo punto luminoso y en las que tenían que maximizar la intensidad percibida del núcleo del punto luminoso o minimizar el tamaño de la imagen percibida (es decir, minimizar el "starburst"). Excepto para la tarea de detección, la luminancia del punto de luz fue de 1000 cd m-2 sobre un fondo negro con un valor inferior a 0,5 cd m-2. Resultados: La AS positiva introdujo cambios miópicos respecto al mejor enfoque subjetivo para letras oscuras sobre un fondo luminoso sin AS, mientras que la AS negativa introdujo cambios hipermetrópicos respecto al enfoque óptimo. Estos cambios fueron -1,7,-2,4,-2,0, y -9,2 D de enfoque por D mm-2 de AS para la tarea de detección, la tarea de resolución, la maximización de la intensidad del núcleo y la minimización de su tamaño, respectivamente. Conclusión: La AS ocular puede ser un factor que influye significativamente en los cambios en el estado refractivo, al visualizar las fuentes puntuales de alto contraste típicas de los entornos nocturnos

Prediction Accuracy of the Dynamic Structure-Function Model for Glaucoma Progression Using Contrast Sensitivity Perimetry and Confocal Scanning Laser Ophthalmoscopy.

PURPOSE: The purpose of this study was to determine whether combining a structural measure with contrast sensitivity perimetry (CSP), which has lower test-retest variability than static automated perimetry (SAP), reduces prediction error with 2 models of glaucoma progression. METHODS: In this retrospective analysis, eyes with 5 visits with rim area (RA), SAP, and CSP measures were selected from 2 datasets. Twenty-six eyes with open-angle glaucoma were included in the analyses. For CSP and SAP, mean sensitivity (MS) was obtained by converting the sensitivity values at each location from decibel (SAP) or log units (CSP) to linear units, and then averaging all values. MS and RA values were expressed as percent of mean normal based on independent normative data. Data from the first 3 and 4 visits were used to calculate errors in prediction for the fourth and fifth visits, respectively. Prediction errors were obtained for simple linear regression and the dynamic structure-function (DSF) model. RESULTS: With linear regression, the median prediction errors ranged from 6% to 17% when SAP MS and RA were used and from 9% to 17% when CSP MS and RA were used. With the DSF model, the median prediction errors ranged from 6% to 11% when SAP MS and RA were used and from 7% to 16% when CSP MS and RA were used. CONCLUSIONS: The DSF model had consistently lower prediction errors than simple linear regression. The lower test-retest variability of CSP in glaucomatous defects did not, however, result in lower prediction error.

Publication bias and the chase for statistical significance / Sesgo en publicación y la búsqueda de significancia estadística

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Associations between structure and function are different in healthy and glaucomatous eyes.

PURPOSE: To assess if there are differences in the structure-function associations between healthy and glaucomatous eyes. METHODS: Structure-function associations were assessed in healthy and glaucomatous eyes in three datasets, globally and in the six sectors of the optic nerve head. Structural parameters included rim area (RA) and retinal nerve fiber layer thickness (RNFLT). Functional parameters included unweighted mean of sensitivity thresholds (MS) and unweighted mean of total deviation values (MD), assessed with standard automated perimetry, short-wavelength automated perimetry, frequency-doubling technology perimetry, or contrast sensitivity perimetry. All structural and functional parameters were expressed as percent of mean normal. SF associations were assessed with correlation analyses (Pearson, Spearman and Kendall). We also assessed the SF associations with linear regression analyses: the generalized estimating equation (GEE) was used to adjust for inter-eye correlations and ordinary least squares (OLS) linear models were used when these adjustments were not necessary. We applied Bonferroni corrections to adjust for the impact of multiple comparisons. RESULTS: Overall, none of the Pearson correlations tested in healthy eyes were significant (correlations ranged from -0.17 to 0.37), whereas 77% of the correlations tested in glaucomatous eyes were significant (correlations ranged from 0.01 to 0.79). Similarly, none of the slopes obtained with GEE and OLS were significant in healthy eyes (slopes ranged from -0.30 to 0.87), whereas 82% of the slopes obtained in glaucomatous eyes were significant (slopes ranged from 0.02 to 1.38). CONCLUSIONS: Significant associations between structure and function were consistently observed in glaucomatous eyes, but not in healthy eyes. These differences in association should be considered in the design of structure-function models for progression.