Changes of ocular aberrations with gaze

Prado, Paula; Arines, Justo; Bará, Salvador; Manzanera, Silvestre; Mira-Agudelo, Alejandro; Artal, Pablo

doi:10.1111/j.1475-1313.2009.00652.x

Cited by 10 publications

(10 citation statements)

References 25 publications

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“…Several studies have shown that unstable tear films will increase irregular astigmatism and bad optical quality. [35]–[38] Moreover, HOA changed dynamically with blinking, even in normal subjects. [39] …”

Section: Discussionmentioning

confidence: 99%

Evaluation of Anterior Segment Parameters and Possible Influencing Factors in Normal Subjects Using a Dual Scheimpflug Analyzer

Wang

Dong

2014

PLoS ONE

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PurposeTo investigate normal anterior segment parameters and analyze the possible influencing factors using a dual Scheimpflug system.SettingDepartment of Ophthalmology, Affiliated Sixth People's Hospital Shanghai Jiao Tong University, Shanghai, China.DesignA prospective observational case series.MethodsA total of 153 normal subjects (153 eyes) were studied. The anterior segment parameters, including the central corneal thickness (CCT), anterior chamber depth (ACD), pupil diameter (PD), keratoconus prediction index (KPI), simulated keratometry (SimK) values, anterior instantaneous curvature (AIC), posterior axial curvature (PAC), corneal eccentricity, total corneal power (TCP), axial curvature (AC), total corneal wavefront (TCW), high order aberration (HOA), and spherical aberration (SA), were determined using a dual Scheimpflug analyzer.ResultsThe CCT and ACD were both negatively correlated with age (r = −0.203, p = 0.012; r = −0.589, p<0.001). There was no significant difference in the refractive indices of AIC and SimK. Compared with the negative correlation of HOA and SA (r = −0.358, p<0.001), a positive correlation was found between TCW and HOA (r = 0.561, p<0.001). Unlike the decreased tendency of AC, the TCP increased gradually from the center to the periphery in the central 8 mm diameter. TCP showed a significant correlation with AC in the analyzed area.ConclusionsAIC and SimK provide different information in clinic, but the refractive indices of them showed no difference in this healthy study population, and age should be considered when using CCT and ACD values.

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Section: Discussionmentioning

confidence: 99%

Evaluation of Anterior Segment Parameters and Possible Influencing Factors in Normal Subjects Using a Dual Scheimpflug Analyzer

Wang

Dong

2014

PLoS ONE

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“…While studies have shown no significant variation in ocular aberrations with horizontal gaze [6], we hypothesize that downward gaze might be different due to lid pressure [9,14–16], gravitational effects [12,13], or perhaps some differences in the biomechanical force from the extraocular muscles. So along with the human eyes, we also measured aberrations from a model eye in primary gaze and downward gaze using the relay lens system to verify that the changes in aberrations found in human eyes in downward gaze were real effects (i.e., optical and physiological changes) rather than representing artefacts induced from the measurement technique.…”

Section: Methodsmentioning

confidence: 94%

“…However, this does not replicate the natural viewing conditions of human eyes for many tasks such as near work or reading that typically involve binocular viewing and near focus (accommodation) in downward gaze. A number of studies [6–8] have shown that changes in horizontal gaze have no significant influence on the optics of the eye compared to primary gaze, however these studies have not investigated changes in ocular optics in downward gaze. A range of biomechanical changes may occur when we adopt a downward gaze that could result in changes of ocular aberrations.…”

Section: Introductionmentioning

confidence: 99%

Measurement of ocular aberrations in downward gaze using a modified clinical aberrometer

Ghosh

Collins

Read

et al. 2011

Biomed. Opt. Express

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Changes in corneal optics have been measured after downward gaze. However, ocular aberrations during downward gaze have not been previously measured. A commercial Shack-Hartmann aberrometer (COAS-HD) was modified by adding a relay lens system and a rotatable beam splitter to allow on-axis aberration measurements in primary gaze and downward gaze with binocular fixation. Measurements with the modified aberrometer (COAS-HD relay system) in primary and downward gaze were validated against a conventional aberrometer. In human eyes, there were significant changes (p<0.05) in defocus C(2,0), primary astigmatism C(2,2) and vertical coma C(3,−1) in downward gaze (25 degrees) compared to primary gaze, indicating the potential influence of biomechanical forces on the optics of the eye in downward gaze. To demonstrate a further clinical application of this modified aberrometer, we measured ocular aberrations when wearing a progressive addition lens (PAL) in primary gaze (0 degree), 15 degrees downward gaze and 25 degrees downward gaze.

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“…Error bars are often large within refractive groups [14,15], and it remains unclear how much of this variability can be attributed to interindividual variability and how much to "noise" of the measurement technique. Turning the eye does not seem to induce significant differences in peripheral refraction and aberrations [16,17]. Nevertheless, the extensive measuring procedure makes it difficult to exclude effects of accommodation when the eye is not cyclopleged.…”

Section: Introductionmentioning

confidence: 98%

Comparison of two scanning instruments to measure peripheral refraction in the human eye

et al. 2012

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To better understand how peripheral refraction affects development of myopia in humans, specialized instruments are fundamental for precise and rapid measurements of refraction over the visual field. We compare here two prototype instruments that measure in a few seconds the peripheral refraction in the eye with high angular resolution over a range of about ±45 deg. One instrument is based on the continuous recording of Hartmann-Shack (HS) images (HS scanner) and the other is based on the photorefraction (PR) principle (PR scanner). On average, good correlations were found between the refraction results provided by the two devices, although it varied across subjects. A detailed statistical analysis of the differences between both instruments was performed based on measurements in 35 young subjects. Both instruments have advantages and disadvantages. The HS scanner also provides the high-order aberration data, while the PR scanner is more compact and has a lower cost. Both instruments are current prototypes, and further optimization is possible to make them even more suitable tools for future visual optics and myopia research and also for different ophthalmic applications.

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Changes of ocular aberrations with gaze

Cited by 10 publications

References 25 publications

Evaluation of Anterior Segment Parameters and Possible Influencing Factors in Normal Subjects Using a Dual Scheimpflug Analyzer

Evaluation of Anterior Segment Parameters and Possible Influencing Factors in Normal Subjects Using a Dual Scheimpflug Analyzer

Measurement of ocular aberrations in downward gaze using a modified clinical aberrometer

Comparison of two scanning instruments to measure peripheral refraction in the human eye

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