Binocular Summation Is Intact in Intermittent Exotropia After Surgery

Purpose: To determine binocular summation of surgically treated intermittent exotropia (IXT) patients by measuring the contrast threshold.Methods: We recruited 38 surgically treated IXT patients aged 8–24 years and 20 age-matched healthy controls. All participants had normal or corrected-to-normal visual acuity (Snellen ≥ 20/20) in both eyes. The IXT patients had undergone the surgery at least a year prior to the study. Twenty-one of them obtained good alignment and 17 experienced a recurrence of exotropia. We measured the observers' monocular and binocular contrast sensitivities (CS) at six spatial frequencies (1.5, 3, 6, 12, 18, 24 cycles/degree) as an index of visual information processing at the threshold level. Binocular summation was evaluated against a baseline model of simple probability summation based on the CS at each spatial frequency and the area under the log contrast sensitivity function (AULCSF).Results: The exo-deviation of IXTs with good alignment was −6.38 ± 3.61 prism diopters (pd) at 33 cm and −5.14 ± 4.07 pd at 5 m. For the patients with recurrence, it was −23.47 ± 5.53 pd and −21.12 ± 4.28 pd, respectively. There was no significant difference in the binocular summation ratio (BSR) between the surgically treated IXT patients, including those with good alignment and recurrence, and normal controls at each spatial frequency [F(2,55) = 0.416, P = 0.662] and AULCSF [F(2,55) = 0.469, P = 0.628]. In addition, the BSR was not associated with stereopsis (r = −0.151, P = 0.365).Conclusion: Our findings of normal contrast sensitivity binocular summation ratio in IXT after surgical treatment suggest that the ability of the visual cortex in processing binocular information is intact at the contrast threshold level.

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Acuity and contrast sensitivity of the bluegill sunfish and how they change during optic nerve regeneration

Visual Neuroscience ◽

10.1017/s0952523807070307 ◽

2007 ◽

Vol 24 (3) ◽

pp. 319-331 ◽

Cited By ~ 17

Author(s):

D.P.M. NORTHMORE ◽

D.-J. OH ◽

M.A. CELENZA

Keyword(s):

Optic Nerve ◽

Spatial Frequency ◽

Contrast Sensitivity ◽

Cutoff Frequency ◽

Lepomis Macrochirus ◽

High Spatial Frequency ◽

Contrast Threshold ◽

Bluegill Sunfish ◽

Sensitivity Functions ◽

Spatial Frequencies

Spatial vision was studied in the bluegill sunfish, Lepomis macrochirus (9.5–14 cm standard length) to assess the limitations imposed by the optics of the eye, the retinal receptor spacing and the retinotectal projection during regeneration. Examination of images formed by the dioptric elements of the eye showed that spatial frequencies up to 29 c/° could be imaged on the retina. Cone spacing was measured in the retina of fresh, intact eyes. The spacing of rows of double cones predicted 3.4 c/° as the cutoff spatial frequency; the spacing between rows of single and double cones predicted 6.7 c/°. Contrast sensitivity functions were obtained psychophysically in normals and fish with one regenerating optic nerve. Fish were trained to orient to gratings (mean luminance = 25 cd/m2) presented to either eye. In normals, contrast sensitivity functions were similar in shape and bandwidth to those of other species, peaking at 0.4 c/° with a minimum contrast threshold of 0.03 and a cutoff at about 5 c/°, which was within the range predicted by cone spacing. Given that the optical cutoff frequency exceeds that predicted by cone spacing, it is possible that gratings could be detected by aliasing with the bluegill's regular cone mosaic. However, tests with high contrast gratings up to 15 c/° found no evidence of such detection. After crushing one optic nerve in three trained sunfish, recovery of visual avoidance, dorsal light reflex and orienting to gratings, were monitored over 315 days. At 64–69 days postcrush, responses to gratings reappeared, and within 2–5 days contrast sensitivity at low (0.15 c/°) and medium (1.0 c/°) spatial frequencies had returned to normal. At a high spatial frequency (2.93 c/°) recovery was much slower, and complete only in one fish.

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Spatial Extent of Masking by Sine-Wave Gratings

Perception ◽

10.1068/v970219 ◽

1997 ◽

Vol 26 (1_suppl) ◽

pp. 74-74 ◽

Cited By ~ 1

Author(s):

V V Babenko

Keyword(s):

Spatial Frequency ◽

Full Range ◽

Threshold Level ◽

Sine Wave ◽

Spatial Extent ◽

Contrast Threshold ◽

Backward Masking ◽

Distributed Information ◽

Spatial Frequencies ◽

Number Of Cycles

The contrast threshold for detection of a target consisting of 1.5 periods of a sine wave was determined as a function of the number of cycles in a sinusoidal mask with the same spatial frequency and orientation. The test frequencies were 2, 4, and 8 cycles deg−1. The masks were spatial-frequency modulated so as to equate their spectral extent. Stimuli were seen monocularly in Maxwellian view at a mean luminance of 10 cd m−2. The contrast threshold in a backward masking paradigm was determined by a 2AFC staircase. Data were obtained from three subjects with normal vision. It was found that as the number of cycles in the mask was increased, the contrast threshold fell, but only to a certain level. The full range of the threshold decrement was about 2 dB. At all the spatial frequencies tested, the final threshold level was reached with 3 cycles in the mask and then remained unaffected by a further increase in the number of cycles. The results implicate frequency-tuned mechanisms of very restricted spatial extent. It is suggested that these may underlie processing of spatially distributed information at the post-striate stages.

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Aspheric Intraocular Lenses Implantation for Cataract Patients with Extreme Myopia

ISRN Ophthalmology ◽

10.1155/2014/403432 ◽

2014 ◽

Vol 2014 ◽

pp. 1-6 ◽

Cited By ~ 3

Author(s):

Yanwen Fang ◽

Yi Lu ◽

Aizhu Miao ◽

Yi Luo

Keyword(s):

Contrast Sensitivity ◽

Visual Quality ◽

Intraocular Lenses ◽

Wavefront Aberrations ◽

Spatial Frequencies ◽

Aspheric Iol ◽

Significant Difference ◽

Composite Scores ◽

Cataract Patients

Objective. To evaluate the postoperative visual quality of cataract patients with extreme myopia after implantation of aspheric intraocular lenses (IOLs). Methods. Thirty-three eyes were enrolled in this prospectivestudy. Eighteen eyes with an axial length longer than 28 mm were included in the extreme myopia group, and the other 15 eyes were included in the nonextreme myopia group. Phacoemulsification and aspheric IOL implantation were performed. Six months after cataract surgery, best-corrected visual acuity (BCVA), contrast sensitivity, and wavefront aberrations were measured, and subjective visual quality was assessed. Results. The BCVA improved significantly after surgery for both groups, and patients in the nonextreme myopia group achieved better postoperative BCVA due to better retinal status of the eyes. The evaluation of contrast sensitivity without glare was the same in both groups, whereas patients in the nonextreme myopia group performed better at intermediate spatial frequencies under glare conditions. The two groups did not show a significant difference in high-order aberrations. With regard to subjective visual quality, the composite scores of both groups did not differ significantly. Conclusions. Aspheric IOLs provided good visual outcomes in cataract patients with extreme myopia. These patients should undergo careful evaluation to determine the maculopathy severity level before surgery.

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Neuronal basis of perceptual learning in striate cortex

Scientific Reports ◽

10.1038/srep24769 ◽

2016 ◽

Vol 6 (1) ◽

Cited By ~ 6

Author(s):

Zhen Ren ◽

Jiawei Zhou ◽

Zhimo Yao ◽

Zhengchun Wang ◽

Nini Yuan ◽

...

Keyword(s):

Spatial Frequency ◽

Perceptual Learning ◽

Contrast Sensitivity ◽

Striate Cortex ◽

Signal To Noise Ratio ◽

High Spatial Frequency ◽

Sensitivity Training ◽

Spatial Frequencies ◽

Cortex Area ◽

Adult Cats

Abstract It is well known that, in humans, contrast sensitivity training at high spatial frequency (SF) not only leads to contrast sensitivity improvement, but also results in an improvement in visual acuity as assessed with gratings (direct effect) or letters (transfer effect). However, the underlying neural mechanisms of this high spatial frequency training improvement remain to be elucidated. In the present study, we examined four properties of neurons in primary visual cortex (area 17) of adult cats that exhibited significantly improved acuity after contrast sensitivity training with a high spatial frequency grating and those of untrained control cats. We found no difference in neuronal contrast sensitivity or tuning width (Width) between the trained and untrained cats. However, the trained cats showed a displacement of the cells’ optimal spatial frequency (OSF) to higher spatial frequencies as well as a larger neuronal signal-to-noise ratio (SNR). Furthermore, both the neuronal differences in OSF and SNR were significantly correlated with the improvement of acuity measured behaviorally. These results suggest that striate neurons might mediate the perceptual learning-induced improvement for high spatial frequency stimuli by an alteration in their spatial frequency representation and by an increased SNR.

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Spatial Integration of Objectively Equiluminous Chromatic Gratings

Perception ◽

10.1068/v970297 ◽

1997 ◽

Vol 26 (1_suppl) ◽

pp. 200-200

Author(s):

M I Kankaanpää ◽

J Rovamo ◽

H T Kukkonen ◽

J Hallikainen

Keyword(s):

Spatial Frequency ◽

Contrast Sensitivity ◽

Spatial Integration ◽

Chromatic Contrast ◽

Shape Difference ◽

Sensitivity Functions ◽

Spatial Frequencies ◽

Low Pass ◽

Chromatic Aberrations ◽

Chromatic Contrast Sensitivity

Contrast sensitivity functions for achromatic and chromatic gratings tend to be band-pass and low-pass in shape, respectively. Our aim was to test whether spatial integration contributes to the shape difference found at low spatial frequencies. We measured binocular chromatic contrast sensitivity as a function of grating area for objectively equiluminous red - green and blue - yellow chromatic gratings. Chromatic contrast refers to the Michelson contrast of either of the two chromatic component gratings presented in counterphase against the combined background. Grating area ( A) varied from 1 to 256 square cycles ( Af2) at spatial frequencies ( f) of 0.125 – 4.0 cycles deg−1. We used only horizontal gratings at low and medium spatial frequencies to minimise the transverse and longitudinal chromatic aberrations due to ocular optics. At all spatial frequencies studied, chromatic contrast sensitivity increased with grating area. Ac was found to be constant at low spatial frequencies (0.125 – 0.5 cycles deg−1) but decreased in inverse proportion to increasing spatial frequency at 1 – 4 cycles deg−1. Thus, spatial integration depends similarly on spatial frequency for achromatic (Luntinen et al, 1995 Vision Research35 2339 – 2346) and chromatic gratings, and differences in spatial integration do not contribute to the shape difference of the respective contrast sensitivity functions.

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Spatial Scale Interactions and Visual-Tracking Performance

Perception ◽

10.1068/p261047 ◽

1997 ◽

Vol 26 (8) ◽

pp. 1047-1058 ◽

Cited By ~ 1

Author(s):

Howard C Hughes ◽

David M Aronchick ◽

Michael D Nelson

Keyword(s):

Spatial Frequency ◽

High Frequency ◽

Visual Information ◽

Low Frequency ◽

High Spatial Frequency ◽

Performance Measure ◽

High Frequency Component ◽

Stimulus Velocity ◽

Spatial Frequencies ◽

Wide Range

It has previously been observed that low spatial frequencies (≤ 1.0 cycles deg−1) tend to dominate high spatial frequencies (≥ 5.0 cycles deg−1) in several types of visual-information-processing tasks. This earlier work employed reaction times as the primary performance measure and the present experiments address the possibility of low-frequency dominance by evaluating visually guided performance of a completely different response system: the control of slow-pursuit eye movements. Slow-pursuit gains (eye velocity/stimulus velocity) were obtained while observers attempted to track the motion of a sine-wave grating. The drifting gratings were presented on three types of background: a uniform background, a background consisting of a stationary grating, or a flickering background. Low-frequency dominance was evident over a wide range of velocities, in that a stationary high-frequency component produced little disruption in the pursuit of a drifting low spatial frequency, but a stationary low frequency interfered substantially with the tracking of a moving high spatial frequency. Pursuit was unaffected by temporal modulation of the background, suggesting that these effects are due to the spatial characteristics of the stationary grating. Similar asymmetries were observed with respect to the stability of fixation: active fixation was less stable in the presence of a drifting low frequency than in the presence of a drifting high frequency.

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An Assessment of Decision-Making as a Possible Factor in the Age-Related Loss of Contrast Sensitivity

Perception ◽

10.1068/p150541 ◽

1986 ◽

Vol 15 (5) ◽

pp. 541-552 ◽

Cited By ~ 13

Author(s):

James D Morrison ◽

James Reilly

Keyword(s):

Decision Making ◽

Contrast Sensitivity ◽

Contrast Threshold ◽

Sinusoidal Grating ◽

Hit Rate ◽

Grating Pattern ◽

Age Related ◽

Spatial Frequencies ◽

Young Subjects ◽

Contrast Thresholds

The possibility that changes in decision-making may contribute to the age-related decline in contrast sensitivity has been investigated in nineteen young subjects (ages 21–38 years) and twenty-seven old subjects (ages 55–92 years). A signal detection paradigm was employed in which the detection of stationary sinusoidal grating patterns was measured at 3 and 15 cycles deg−1 for a range of contrasts which were psychophysically equivalent for each subject. A decline in contrast sensitivity with age at the spatial frequencies studied was confirmed for contrast thresholds obtained both by the ascending method and from the 50% hit rate for detection of the grating pattern. The criterion adopted for decision-making, expressed as both β and percentage bias, did not change significantly between young and old subjects at 15 cycles deg−1. At 3 cycles deg−1, criterion β did not change significantly at x0.8, x1.0, or x1.2 contrast threshold, but at contrast giving 50% hit rate there was a significant increase with age. The percentage bias increased significantly at contrast threshold but not at 50% hit rate. It is inferred from the results that the loss of contrast sensitivity was not accountable in terms of the adoption of a more conservative criterion by older subjects. Hence visual loss in ageing is attributed to changes within the visual pathway rather than within higher decision-making centres.

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Low Spatial Frequency Contrast Sensitivity Deficits in Migraine are not Visual Pathway Selective

Cephalalgia ◽

10.1111/j.1468-2982.2008.01817.x ◽

2009 ◽

Vol 29 (5) ◽

pp. 539-549 ◽

Cited By ~ 17

Author(s):

AM McKendrick ◽

GP Sampson

Keyword(s):

Spatial Frequency ◽

Contrast Sensitivity ◽

Parvocellular Pathway ◽

Functional Deficits ◽

Visual Contrast ◽

Sensitivity Loss ◽

Significant Difference ◽

Pathway Function ◽

Migraine Group ◽

Visual Contrast Sensitivity

Some people who experience migraine demonstrate reduced visual contrast sensitivity that is measurable between migraines. Contrast sensitivity loss to low spatial frequency gratings has been previously attributed to possible impairment of magnocellular pathway function. This study measured contrast sensitivity using low spatial frequency targets (0.25–4 c/deg) where the adaptation aspects of the stimuli were designed to preferentially assess either magnocellular or parvocellular pathway function (steady and pulsed pedestal technique). Twelve people with migraine with measured visual field abnormalities and 17 controls participated. Subjects were tested foveally and at 10° eccentricity. Foveally, there was no significant difference in group mean contrast sensitivity. At 10°, the migraine group demonstrated reduced contrast sensitivity for both the stimuli designed to assess magnocellular and parvocellular function ( P < 0.05). The functional deficits measured in this study infer that abnormalities of the low spatial frequency sensitive channels of both pathways contribute to contrast sensitivity deficits in people with migraine.

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Visual performance of four types of diffractive multifocal intraocular lenses and a review of articles

International Journal of Ophthalmology ◽

10.18240/ijo.2021.03.04 ◽

2021 ◽

Vol 14 (3) ◽

pp. 356-365

Author(s):

Farideh Doroodgar ◽

◽

Azad Sanginabadi ◽

Farid Karimian ◽

Sana Niazi ◽

...

Keyword(s):

Visual Acuity ◽

Contrast Sensitivity ◽

Intraocular Lenses ◽

Multifocal Intraocular Lenses ◽

Spatial Frequencies ◽

Signed Rank ◽

Pubmed Database ◽

Significant Difference ◽

The One ◽

Post Hoc

AIM: To compare the clinical outcomes of a variety of multifocal intraocular lenses (MIOLs) in patients diagnosed with presbyopia or cataracts. METHODS: This clinical trial study included 141 patients (282 eyes) with different MIOLs implantation. The Symfony (60 eyes), the ReSTOR (100 eyes), the AT LISAtri (60 eyes), and the PanOptix (62 eyes) intraocular lenses were evaluated in this prospective interventional study. The near, intermediate, and distant visual acuities, contrast sensitivity, and defocus curve were measured as valid criteria. To statistically analyze the results, we used the Statistical Package for Social Science software, the non-parametric Wilcoxon signed-rank t, the one-way analysis of variance and the Tukey's post-hoc test in our analysis. Moreover, we conducted a detailed literature search on the PubMed database in English about MIOLs, in total 59 studies were included in this review article. RESULTS: The four approaches did not show any significant difference in the best-corrected distance visual acuity (P>0.05). The defocus curves at the contrast of 100% showed that trifocal IOLs had better intermediate performance than the bifocal IOL (P<0.05). There were no statistically significant differences between AT LISAtri and PanOptix lenses for visual acuity at all distances. The eyes with PanOptix, Symfony, and AT LISAtri IOL showed better contrast sensitivity than those ReSTOR at spatial frequencies of 1, 3, and 6 cpd in photopic and mesopic conditions (P<0.001). CONCLUSION: All four groups of the multifocal lenses were satisfying in terms of distance and near vision. Also, the group of trifocal lenses led to satisfactory outcomes in intermediate vision, without degradation in quality of vision.

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Photopic and Mesopic Contrast Sensitivity Function in the Presence of Glare and the Effect of Filters in Young Healthy Adults

Frontiers in Psychology ◽

10.3389/fpsyg.2021.772661 ◽

2021 ◽

Vol 12 ◽

Author(s):

Alberto Domínguez-Vicent ◽

Emma Helghe ◽

Marika Wahlberg Ramsay ◽

Abinaya Priya Venkataraman

Keyword(s):

Contrast Sensitivity ◽

Light Transmission ◽

Luminance Contrast ◽

Sensitivity Function ◽

Contrast Sensitivity Function ◽

Selective Absorption ◽

Light Reduction ◽

Spatial Frequencies ◽

Significant Difference ◽

Young Subjects

Purpose: The aim of this study was to evaluate the effect of four different filters on contrast sensitivity under photopic and mesopic conditions with and without glare.Methods: A forced choice algorithm in a Bayesian psychophysical procedure was utilized to evaluate the spatial luminance contrast sensitivity. Five different spatial frequencies were evaluated: 1.5, 3, 6, 12, and 18 cycles per degree (cpd). The measurements were performed under 4 settings: photopic and mesopic luminance with glare and no glare. Two long pass filters (LED light reduction and 511nm filter) and two selective absorption filters (ML41 and emerald filter) and a no filter condition were evaluated. The measurements were performed in 9 young subjects with healthy eyes.Results: For the no filter condition, there was no difference between glare and no glare settings for the photopic contrast sensitivity measurements whereas in the mesopic setting, glare reduced the contrast sensitivity significantly at all spatial frequencies. There was no statistically significant difference between contrast sensitivity measurements obtained with different filters under both photopic conditions and the mesopic glare condition. In the mesopic no glare condition, the contrast sensitivity at 6 cpd with 511, ML41 and emerald filters was significantly reduced compared to no filter condition (p = 0.045, 0.045, and 0.071, respectively). Similarly, with these filters the area under the contrast sensitivity function in the mesopic no glare condition was also reduced. A significant positive correlation was seen between the filter light transmission and the average AULCSF in the mesopic non-glare condition.Conclusion: The contrast sensitivity measured with the filters was not significantly different than the no filter condition in photopic glare and no glare setting as well as in mesopic glare setting. In mesopic setting with no glare, filters reduced contrast sensitivity.

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