Contrast Sensitivity Measurements Research Articles

Visual outcomes after refractive laser corneal surgery and phakic IOL in amblyopic eyes.

To evaluate the outcomes of laser corneal surgery and phakic IOL surgery in adult amblyopic eyes. Retrospective assessment was done in 688 amblyopic eyes 640 patients who underwent LASIK or phakic IOLs. Ophthalmological evaluation included measurement of uncorrected (UDVA) and corrected (CDVA) distance visual acuities. Analysis of modulation transfer function (MTF) was also done post-operatively as a measure of contrast sensitivity. Patients completed follow-up examinations at 1day, 3day, 3months and 12months after surgery. The mean patient age was 24.30 ± 3.04years with 59% females. The CDVA of amblyopic eyes improved significantly from the mean preoperative level of 0.48 ± 0.18 to 0.59 ± 0.18 at 12months. There was improvement in the contrast sensitivity at all spatial frequencies. Refractive errors were corrected in both LASIK and phakic IOL group, but there was no clinically significant difference in visual outcomes between each group. Laser vision correction and phakic IOL surgery for amblyopic eyes are promising alternative methods for improving visual outcomes in adult refractive amblyopia patients who have failed with conventional approaches.

Long-term objective and subjective outcomes following bilateral implantation of diffractive bifocal or trifocal intraocular lenses.

To evaluate and compare the objective and subjective outcomes after the bilateral implantation of a diffractive bifocal and trifocal intraocular lens. This is a case-control, single-center observational study which included 27 patients; 16 patients were implanted bilaterally with the bifocal AcrySof IQ ReSTOR+3.0D and 11 patients with the trifocal AT LISA tri 839MP. Uncorrected visual acuity at distance, intermediate, and near under mesopic and photopic conditions using ETDRS charts with 10% and 100% contrast, corrected distance visual acuity, and binocular defocus curve in photopic conditions; binocular contrast sensitivity under mesopic and photopic conditions for far and near distances were assessed. The Visual Function Questionnaire-25 questionnaire was used to assess patients' satisfaction. All the measurements were performed 6-24 months after cataract surgery. The ReSTOR group had better binocular uncorrected near visual acuity in photopic conditions with low and high contrast charts (p = 0.040 and p = 0.033, respectively), as well as in far contrast sensitivity measurement under mesopic conditions with a spatial frequency of 3 cycles per degree (p = 0.034). There was not a significant difference between the two study groups in uncorrected near, intermediate or distance vision under mesopic conditions. The AT LISA tri study group had better subjective outcomes. Both intraocular lenses restore visual acuity after cataract surgery. The ReSTOR intraocular lens provides better objective outcomes than the AT LISA tri, although the latter provides better subjective outcomes. The relevance of this study is the evaluation of both objective and subjective outcomes.

Assessment of contrast sensitivity in pre & post trans-epithelial photorefractive keratectomy

Purpose: study was to compare the contrast sensitivity before and after Trans- PRK. Methods: The comparative study was conducted in department of ophthalmology medina teaching hospital Faisalabad. Total 30 myopic volunteers of both genders, with ages ranging from 20 years to 35 years, who had not undergone any ocular surgery or medical treatment for systemic or ocular diseases e.g. diabetes, Alzheimer's disease, glaucoma, macular degeneration, dry eye and cataract. Data was collected through non-probability convenient sampling technique from Sep 2018- May 2019. Data was entered in to SPSS version 20 and analyzed by using Paired sample t-test. Results: Significant improvement was seen in contrast sensitivity after Trans-PRK 0.00 (p<0.005) by paired sample t-test. Contrast sensitivity test before and after Trans-PRK of right and left eye showed mean of right eye -.41533±0.18678 and left eye mean -.22167±0.24378 respectively. Conclusion: Our research concluded that, there is greater statistical difference between before and after Trans-PRK contrast sensitivity measurements. Contrast sensitivity improves after surgery significantly. Trans-PRK procedure is best method to correct refractive errors and removal of glasses and contact lens permanently with minimum chance of complications.

Impact of glaucoma on executive function and visual search.

Executive function and visual search are linked to a number of activities of daily living including driving and mobility. Using a computerised version of the Trail Making Test B (TMT-B), we compared the executive function and visual search ability of older adults with glaucoma to age-similar controls and identified which visual function tests best predict TMT-B performance. Novel low-contrast and shifting-target variations of the test were incorporated to explore the effects of different levels of test complexity. Thirty-one older adults with mild to moderate glaucoma (mean age=71.2years [SD 6.9]; better-eye mean deviation [MD]: median=-1.9dB [IQR=-1.2 to 0.4], worse-eye MD: median=-11.1dB [IQR=-14.0 to -7.7]) and 24 age-similar controls (mean age=71.9years [SD 6.6]) with normal vision participated. The groups were matched in age, sex, and cognitive status (mini-mental state examination [MMSE]). Participants underwent measurements of visual acuity, contrast sensitivity (CS), visual fields, and visual processing speeds using the useful field-of-view (UFoV). Participants then completed four variations of a computerised TMT-B test, with different levels of complexity based on target contrast (high/low-contrast) and shifts in target position (fixed/shifting locations). Linear mixed-effect models were used to explore the effects of group, target contrast and shift on TMT-B completion time. The glaucoma group took 17.3s longer than controls to complete the TMT-B (P=0.028). All participants took 6.5s longer to complete the low- compared to the high-contrast tests (P=0.012), and 10.6s longer for the shifting TMT-B compared to the fixed version (P<0.001). There was no interaction effect between group, contrast, or target shift on completion time. Across all tests and participant groups, longer completion time was associated with slower UFoV processing speeds (divided attention: P=0.003; selective attention: P=0.006). Poorer CS was associated with longer completion times for the low (P=0.007), but not the high-contrast tests. Our findings suggest that older adults with mild to moderate glaucoma have poorer visual search ability and executive function relative to controls. However, decreasing target contrast or shifting target position did not exacerbate the effects of glaucomatous visual impairment on performance. The UFoV was a strong predictor of TMT-B performance.

Vitreous and Vision Degrading Myodesopsia.

Macromolecules comprise only 2% of vitreous, yet are responsible for its gel state, transparency, and physiologic function(s) within the eye. Myopia and aging alter collagen and hyaluronan association causing concurrent gel liquefaction and fibrous degeneration. The resulting vitreous opacities and collapse of the vitreous body during posterior vitreous detachment are the most common causes for the visual phenomenon of vitreous floaters. Previously considered innocuous, the vitreous opacities that cause floaters sometimes impact vision by profoundly degrading contrast sensitivity function and impairing quality-of-life. While many people adapt to vitreous floaters, clinically significant cases can be diagnosed with Vision Degrading Myodesopsia based upon echographic assessment of vitreous structure and by measuring contrast sensitivity function. Perhaps due to the ubiquity of floaters, the medical profession has to date largely ignored the plight of those with Vision Degrading Myodesopsia. Improved diagnostics will enable better disease staging and more accurate identification of severe cases that merit therapy. YAG laser treatments may occasionally be slightly effective, but vitrectomy is currently the definitive cure. Future developments will usher in more informative diagnostic approaches as well as safer and more effective therapeutic strategies. Improved laser treatments, new pharmacotherapies, and possibly non-invasive optical corrections are exciting new approaches to pursue. Ultimately, enhanced understanding of the underlying pathogenesis of Vision Degrading Myodesopsia should result in prevention, the ultimate goal of modern Medicine.

This issue of acta

This issue of acta

Low frequency transcranial magnetic stimulation of right posterior parietal cortex reduces reaction time to perithreshold low spatial frequency visual\xa0stimuli

Research in humans and animal models suggests that visual responses in early visual cortical areas may be modulated by top-down influences from distant cortical areas, particularly in the frontal and parietal regions. The right posterior parietal cortex is part of a broad cortical network involved in aspects of visual search and attention, but its role in modulating activity in early visual cortical areas is less well understood. This study evaluated the influence of right posterior parietal cortex (PPC) on a direct measure of visual processing in humans. Contrast sensitivity (CS) and detection response times were recorded using a visual detection paradigm to two types of centrally-presented stimuli. Participants were tested on the detection task before, after, and 1 hour after low-frequency repetitive transcranial magnetic stimulation (rTMS) to the right PPC or to the scalp vertex. Low-frequency rTMS to the right PPC did not significantly change measures of contrast sensitivity, but increased the speed at which participants responded to visual stimuli of low spatial frequency. Response times returned to baseline 1-hour after rTMS. These data indicate that low frequency rTMS to the right PPC speeds up aspects of early visual processing, likely due to a disinhibition of the homotopic left posterior parietal cortex.

Evaluation of contrast sensitivity in patients with advanced glaucoma: comparison of two tests

AimsTo evaluate contrast sensitivity (CS) in patients with advanced glaucomatous visual field damage, and to compare two clinical CS tests.MethodsThis was a cross-sectional test–retest study. Twenty-eight patients with open-angle glaucoma,...

正弦光栅用于成人对比敏感度量测之研究

正弦光栅用于成人对比敏感度量测之研究

Visual contrast sensitivity is associated with the presence of cerebral amyloid and tau deposition.

Visual deficits are common in neurodegenerative diseases including Alzheimer’s disease. We sought to determine the association between visual contrast sensitivity and neuroimaging measures of Alzheimer’s disease-related pathophysiology, including cerebral amyloid and tau deposition and neurodegeneration. A total of 74 participants (7 Alzheimer’s disease, 16 mild cognitive impairment, 20 subjective cognitive decline, 31 cognitively normal older adults) underwent the frequency doubling technology 24-2 examination, a structural MRI scan and amyloid PET imaging for the assessment of visual contrast sensitivity. Of these participants, 46 participants (2 Alzheimer’s disease, 9 mild cognitive impairment, 12 subjective cognitive decline, 23 cognitively normal older adults) also underwent tau PET imaging with [18F]flortaucipir. The relationships between visual contrast sensitivity and cerebral amyloid and tau, as well as neurodegeneration, were assessed using partial Pearson correlations, covaried for age, sex and race and ethnicity. Voxel-wise associations were also evaluated for amyloid and tau. The ability of visual contrast sensitivity to predict amyloid and tau positivity were assessed using forward conditional logistic regression and receiver operating curve analysis. All analyses first were done in the full sample and then in the non-demented at-risk individuals (subjective cognitive decline and mild cognitive impairment) only. Significant associations between visual contrast sensitivity and regional amyloid and tau deposition were observed across the full sample and within subjective cognitive decline and mild cognitive impairment only. Voxel-wise analysis demonstrated strong associations of visual contrast sensitivity with amyloid and tau, primarily in temporal, parietal and occipital brain regions. Finally, visual contrast sensitivity accurately predicted amyloid and tau positivity. Alterations in visual contrast sensitivity were related to cerebral deposition of amyloid and tau, suggesting that this measure may be a good biomarker for detecting Alzheimer’s disease-related pathophysiology. Future studies in larger patient samples are needed, but these findings support the power of these measures of visual contrast sensitivity as a potential novel, inexpensive and easy-to-administer biomarker for Alzheimer’s disease-related pathology in older adults at risk for cognitive decline.

A prospective evaluation of ocular toxicity in patients receiving ethambutol as anti-tubercular therapy

Purpose: The purpose of this study was to detect the early ocular toxicity of ethambutol in tuberculosis patients. Materials and Methods: This was a prospective, nonrandomized noncomparative cross-sectional cohort study of consecutive 93 patients (186 eyes) getting anti-tubercular therapy, including ethambutol (15–20 mg/kg/day) along with isoniazid, rifampicin, and pyrazinamide. The duration of the study was 1 year from June 1, 2018 to May 31, 2019. Best-corrected visual acuity (BCVA), color vision, visual field, contrast sensitivity, pattern-reversal visual evoked responses (VER), and retinal nerve fiber layer (RNFL) thickness measurements were done in both eyes of each patient at baseline and thereafter at 1st, 2nd, and 6th months of therapy. Results: Mean age of the patients was 29.38 ± 8.43 years (range 11–58 years). Among them, 53 were male and 40 were female. All the visual parameters were normal at baseline and 1st month of therapy. Mean BCVA was significantly decreased at the 2nd month but improved at the 6th month. In the 2nd month of treatment, abnormal color vision was detected in 8 patients (16 eyes; 8.6%). Three patients developed bilateral central scotoma, which persisted in two patients even after 6 months of follow-up. The mean latency in VER was significantly increased from baseline at 2nd and 6th months of therapy. The mean contrast sensitivity in both eyes was significantly decreased from baseline at the 2nd month of therapy but improved at 6th month. Mean temporal RNFL thickness was significantly reduced from baseline assessment after 2 and 6 months of treatment. Conclusion: The assessment of BCVA, Colour vision, Visual field, Contrast sensitivity, VER, and RNFL thickness measurements are essential at baseline and thereafter at monthly intervals to detect early ocular ethambutol toxicity.

Long-term course of contrast sensitivity in eyes after laser-assisted in-situ keratomileusis for myopia.

Purpose:To evaluate the long-term contrast sensitivity (CS) after laser in-situ keratomileusis (LASIK) for myopia.Methods:This retrospective, single-center, cohort study involved 190 eyes of 95 patients who underwent bilateral LASIK between January 2001 and October 2007. This study includes patients who underwent CS and higher-order aberration (HOA) measurements in a five-year postoperative period. For all enrolled patients, visual acuity, refractive error (RE) in diopters (D), CS at 3-, 6-, 12-, and 18-cycles per degree (cpd), and HOA in a 4 mm area of the dilated pupil were measured before surgery and 6 months, 1 year, and 5 years after it.Results:The mean RE measured before the surgery and after 6 months, 1 year, and 5 years after was - 6.08 ± 2.50D, −0.26 ± 0.65D, −0.28 ± 0.65D, and −0.48 ± 0.80D, respectively. There were no clinically significant changes between preoperative results and the measures taken 6 months, 1 year, and 5 years after surgery. The slight increase in HOA had little effect on CS over the mid to long-term postoperative period.Conclusion:Our findings show that CS does not clinically change post LASIK. Although we were unable to identify the specific mechanism, we theorize that after LASIK there is a possibility for the compensation of HOA.

Reliability of Mesopic Measures of Visual Acuity and Contrast Sensitivity and Their Correlation with Rod and Cone Function in Retinitis Pigmentosa

Background: Mesopic conditions elicit both rod and cone responses, and they are more commonly encountered in daily life than are scotopic conditions; yet visual function outcome measures of mesopic visual acuity (VA) or contrast sensitivity (CS) are rarely evaluated. Objective: In retinitis pigmentosa (RP), we explored whether visual reductions in mesopic versus photopic conditions were correlated with cone or rod function, as well as the between-visit test-retest variability in mesopic measures. Methods: At each of two visits, 22 RP subjects completed mesopic and photopic ETDRS VA and Pelli-Robson chart CS tests obtained with and without a U23 NoIR 4% transmission filter; testing of perifoveal scotopic cone or rod sensitivity with the AdaptDx; and the Rabin Cone Contrast Test (CCT). Results: A greater CS reduction in mesopic versus photopic conditions was significantly related to absence of scotopic rod function (p = 0.038) or longer self-reported duration of night vision loss (p = 0.044). VA reductions >0.2 logMAR in mesopic versus photopic conditions were significantly related to reduced cone-mediated scotopic sensitivity (p = 0.038). Significant predictors of the CCT ratio of S-cone to M- and L-cone sensitivity were mesopic VA (p = 0.038) and absence of AdaptDx rod function (p = 0.008). Test-retest 95% coefficients of repeatability were not significantly different when comparing between photopic and mesopic tests of VA (0.16 and 0.12 logMAR, respectively) or CS (0.21 and 0.24 logCS, respectively). Conclusions: Perifoveal scotopic rod and cone function measured with the AdaptDx was significantly correlated with mesopic CS and VA, respectively, which had good, acceptable test-retest repeatability; thus, they appear to be suitable outcome measures to monitor mesopic visual function in clinical practice or trials. RP subjects with reduced mesopic VA and no perifoveal rod function had a greater loss of sensitivity for S-cones than for L-/M-cones.

Visual-motor expertise in athletes: Insights from semiparametric modelling of 2317 athletes tested on the Nike SPARQ Sensory Station

ABSTRACTElite athletes not only run faster, hit harder, and jump higher, but also see and react better. However, the specific visual-motor skills that differentiate high-achieving athletes are still not well understood. In this paper we examine 2317 athletes (1871 male) tested on the Nike SPARQ Sensory Station, a digital test battery measuring visual, perceptual and motor skills relevant for sports performance. We develop a multivariate Gaussian transformation model to robustly estimate visual-motor differences by level, gender, and sport type. Results demonstrate that visual-motor performance is superior for athletes at higher levels, with males faster at near-far eye movements and females faster at eye-hand reaction times. Interestingly, athletes who play interceptive sports such as baseball and tennis exhibit better measures of visual clarity, contrast sensitivity and simple reaction time, while athletes from strategic sports like soccer and basketball have higher measures of spatial working memory. These findings provide quantitative evidence of domain-specific visual expertise in athletes.

Measurement of CIELAB spatio-chromatic contrast sensitivity in different spatial and chromatic directions

This paper presents data on CIELAB chromatic contrast sensitivity collected in a psychophysical experiment. To complement previously published data in the low-frequency range, we selected five spatial frequencies in the range from 2.4 to 19.1 cycles per degree (cpd). A Gabor stimulus was modulated along six chromatic directions in the a*-b* plane. We also investigated the impact on contrast sensitivity from spatial orientations – both vertically and diagonally oriented stimuli were used. The analysis of the collected data showed lowest contrast sensitivity in the chromatic direction of around 120° from the positive a*-axis. The contrast sensitivity in the diagonal spatial orientation is slightly lower when compared to the vertical orientation.

Comparison of three different diffractıve multifocal intraocular lenses with a +2.5, +3.0, and +3.75 diopter additıon power

PurposeTo compare the functional outcomes and astigmatic tolerability after implantation of multifocal intraocular lenses (IOLs) with a +2.5, +3.0, and +3.75 diopter (D) addition power. MethodsThis study included 122 eyes of 61 patients who had bilateral cataract extraction and implantation of diffractive aspheric multifocal acrylic IOLs with +2.5 D (+2.5 group), +3.0 D (+3.0 group), and +3.75 D (+3.75 group) addition powers. 1-year after surgery, distance corrected near (DNVA) and intermediate (DIVA) visual acuities at 32, 40, 45, 50, 55, and 60 cm; and contrast sensitivity measurements under photopic, mesopic and mesopic with glare conditions; spherical and astigmatic defocus testing; distance-intermediate-near vision patient satisfaction levels; spectacle dependance; patient-reported outcomes were assessed binocularly. ResultsThe +2.50 D group had better DIVA than both +3.0 group and +3.75 groups at 45 cm, 50 cm, 55 cm, and 60 cm (p < 0.05). The +3.75 group had better DNVA than both +2.5 and +3.0 IOL groups at 32 cm (p < 0.05). There was no significant difference in mean contrast values at all frequencies between three IOL groups (p > 0.05). The +2.50 D group showed better astigmatic tolerability than +3.00 group (at 2.00 D) and +3.75 group (at 1.50 D, and at 2.00 D) (p < 0.05). ConclusionMultifocal IOLs with +2.5 add power have better intermediate vision, but worse near vision compared to multifocal IOLs with +3.00 D and +3.75 D add power. Multifocal IOLs with +2.50 D add power tend to have better astigmatic defocus tolerability than multifocal IOLs with +3.00 D and +3.75 D add powers.

Visual tests predict dementia risk in Parkinson disease.

ObjectiveTo assess the role of visual measures and retinal volume to predict the risk of Parkinson disease (PD) dementia.MethodsIn this cohort study, we collected visual, cognitive, and motor data in people with PD. Participants underwent ophthalmic examination, retinal imaging using optical coherence tomography, and visual assessment including acuity and contrast sensitivity and high-level visuoperception measures of skew tolerance and biological motion. We assessed the risk of PD dementia using a recently described algorithm that combines age at onset, sex, depression, motor scores, and baseline cognition.ResultsOne hundred forty-six people were included in the study (112 with PD and 34 age-matched controls). The mean disease duration was 4.1 (±2·5) years. None of these participants had dementia. Higher risk of dementia was associated with poorer performance in visual measures (acuity: ρ = 0.29, p = 0.0024; contrast sensitivity: ρ = −0.37, p < 0.0001; skew tolerance: ρ = −0.25, p = 0.0073; and biological motion: ρ = −0.26, p = 0.0054). In addition, higher risk of PD dementia was associated with thinner retinal structure in layers containing dopaminergic cells, measured as ganglion cell layer (GCL) and inner plexiform layer (IPL) thinning (ρ = −0.29, p = 0.0021; ρ = −0.33, p = 0.00044). These relationships were not seen for the retinal nerve fiber layer that does not contain dopaminergic cells and were not seen in unaffected controls.ConclusionVisual measures and retinal structure in dopaminergic layers were related to risk of PD dementia. Our findings suggest that visual measures and retinal GCL and IPL volumes may be useful to predict the risk of dementia in PD.

Contrast sensitivity is associated with outer-retina thickness in early-stage diabetic retinopathy.

To determine the relationship between contrast sensitivity (CS) and outer-retina thickness (ORT) in diabetics who have minimal or no diabetic retinopathy (DR). Twenty non-diabetic control subjects and 40 type-2 diabetic subjects participated (20 had no clinically apparent DR [NDR] and 20 had mild non-proliferative DR [NPDR]). No subject had a history of treatment for macular oedema. Letter CS, microperimetry (MP) sensitivity and visual acuity (VA) were measured. Letter CS and MP measurements were performed over the central 6° of the visual field. Spectral domain optical coherence tomography (SD-OCT) images were obtained at corresponding locations, outer-retina thickness was quantified, and structure-function relationships were evaluated. Analysis of variance indicated significant letter CS differences among the groups (p<0.001). Letter CS was reduced significantly for the mild NPDR group (p<0.001; 33% reduction), but not the NDR group (p=0.08). There were no significant differences in MP sensitivity or ORT among the groups (both p>0.10). Nevertheless, Hoeffding's D tests indicated significant associations between ORT and letter CS (p<0.001) and between ORT and MP sensitivity for the mild NPDR group (p=0.01). VA was not significantly associated with ORT for either diabetic group (both p>0.49). Outer-retina thickness is associated with letter CS and MP sensitivity, but not VA, in mild NPDR. This finding highlights the usefulness of simple letter CS measures and suggests neural dysfunction can occur in the absence of marked structural abnormalities in early-stage DR.

Consideration of eye movements reconciles behavioral and neuronal measures of contrast sensitivity

Consideration of eye movements reconciles behavioral and neuronal measures of contrast sensitivity

Spatial Frequency Tuning and Transfer of Perceptual Learning for Motion Coherence Reflects the Tuning Properties of Global Motion Processing.

Perceptual learning is typically highly specific to the stimuli and task used during training. However, recently, it has been shown that training on global motion can transfer to untrained tasks, reflecting the generalising properties of mechanisms at this level of processing. We investigated (i) if feedback was required for learning in a motion coherence task, (ii) the transfer across the spatial frequency of training on a global motion coherence task and (iii) the transfer of this training to a measure of contrast sensitivity. For our first experiment, two groups, with and without feedback, trained for ten days on a broadband motion coherence task. Results indicated that feedback was a requirement for robust learning. For the second experiment, training consisted of five days of direction discrimination using one of three motion coherence stimuli (where individual elements were comprised of either broadband Gaussian blobs or low- or high-frequency random-dot Gabor patches), with trial-by-trial auditory feedback. A pre- and post-training assessment was conducted for each of the three types of global motion coherence conditions and high and low spatial frequency contrast sensitivity (both without feedback). Our training paradigm was successful at eliciting improvement in the trained tasks over the five days. Post-training assessments found evidence of transfer for the motion coherence task exclusively for the group trained on low spatial frequency elements. For the contrast sensitivity tasks, improved performance was observed for low- and high-frequency stimuli, following motion coherence training with broadband stimuli, and for low-frequency stimuli, following low-frequency training. Our findings are consistent with perceptual learning, which depends on the global stage of motion processing in higher cortical areas, which is broadly tuned for spatial frequency, with a preference for low frequencies.