Color Contrast Sensitivity Research Articles

The effect of space—frequency characteristics of the organ of vision on the human psychophysiological state and working capacity

During the long-term stay in closed environment of the orbital space station, it is extremely important that the light conditions and color scheme were favorable for the working capacity of a cosmonaut. The systems of lighting should ensure visual comfort for the crew members under stressful conditions and, in addition, they should appropriate to their health and recovery of functional reserves during the long-duration flight. To solve this task, the distribution of luminosity and chromaticity within a closed space should be taken into account. For better understanding the perception of visual information, we studied the color space-frequency characteristics of the organ of vision (SFC VO). A set of sensors was used to estimate psychophysiological parameters. After preadaptation of an operator, VO contrast sensitivity was measured by determining the thresholds of advent and disappearance of the test objects; this was accompanied by fixation of the time and adaptive brightness. Analysis of the experimental data made it clear that the color contrast sensitivity and directly related SFC of the organ of vision are valuable markers for interrelationships between processing of visual information and psychophysiological state of a human. Note that the color SFC VO not only illustrates deviations but also enables their quantification. Changes in psychophysiological state are accompanied by the appropriate changes in SFC VO, which should be taken into account in developing the neural information technologies used for health recovery and light-and-color control of environment.

A randomized placebo-controlled trial of idebenone in Leber’s hereditary optic neuropathy

Major advances in understanding the pathogenesis of inherited metabolic disease caused by mitochondrial DNA mutations have yet to translate into treatments of proven efficacy. Leber’s hereditary optic neuropathy is the most common mitochondrial DNA disorder causing irreversible blindness in young adult life. Anecdotal reports support the use of idebenone in Leber’s hereditary optic neuropathy, but this has not been evaluated in a randomized controlled trial. We conducted a 24-week multi-centre double-blind, randomized, placebo-controlled trial in 85 patients with Leber’s hereditary optic neuropathy due to m.3460G>A, m.11778G>A, and m.14484T>C or mitochondrial DNA mutations. The active drug was idebenone 900 mg/day. The primary end-point was the best recovery in visual acuity. The main secondary end-point was the change in best visual acuity. Other secondary end-points were changes in visual acuity of the best eye at baseline and changes in visual acuity for both eyes in each patient. Colour-contrast sensitivity and retinal nerve fibre layer thickness were measured in subgroups. Idebenone was safe and well tolerated. The primary end-point did not reach statistical significance in the intention to treat population. However, post hoc interaction analysis showed a different response to idebenone in patients with discordant visual acuities at baseline; in these patients, all secondary end-points were significantly different between the idebenone and placebo groups. This first randomized controlled trial in the mitochondrial disorder, Leber’s hereditary optic neuropathy, provides evidence that patients with discordant visual acuities are the most likely to benefit from idebenone treatment, which is safe and well tolerated.

P‐44: Color Uniformity Grade Evaluation of Electronic Displays Based on Color Contrast Sensitivity

AbstractElectronic displays have non‐uniform regions of chromaticity. In the present paper, a novel method that evaluates the mura grade of electronic displays using a chromaticity mura index E is presented. The index E is calculated using a filtered image obtained by the color contrast sensitivity function.

Evaluation of Retinal Function and Flicker Light-Induced Retinal Vascular Response in Normotensive Patients with Diabetes without Retinopathy

To correlate retinal function with vascular response to flicker light in normotensive patients with diabetes without diabetic retinopathy (DR). Twenty-eight normotensive patients with diabetes (11 with type 1, 17 with type 2) without DR and 28 sex- and age-matched healthy control subjects underwent color vision and contrast sensitivity testing, pattern, full-field, and multifocal electroretinography, and evaluation of the vascular response to flicker light with the dynamic vessel analyzer. In the patients with diabetes, electroretinogram (ERG) pattern responses, b-wave in the scotopic bright flash ERG, a-wave and b-wave in the photopic single-flash ERG, and oscillatory potential responses were significantly impaired compared with those in control subjects. Vascular response to flicker light was also impaired in patients with diabetes compared with controls. In the whole population, correlations were found between flicker light-induced arterial retinal vasodilation and the amplitude and implicit time of the N95 wave of pattern ERG (r = -0.27, P = 0.047 and r = -0.35, P = 0.008, respectively), the b-wave implicit time of rod ERG (r = -0.36; P = 0.01) and the oscillatory potentials (r = 0.4; P = 0.003), suggesting that impairment of the vascular response to flicker light may reflect inner retinal neural impairment. However, no correlation between these factors was found when only patients with diabetes were considered. In patients with diabetes, neural and neurovascular dysfunctions both precede the onset of clinically detectable DR. To which extent these abnormalities are related to each other remains to be determined. (ClinicalTrials.gov number, NCT00839150.)

Funciones visuales en portadores del virus de inmunodeficiencia humana

Objective To determine whether there are changes in the peripapillary nerve fibre layer, in colour vision, contrast sensitivity, dark adaptation and electroretinography changes in these patients who do not have infectious retinitis. Methods We studied 52 patients without ocular pathology; the mean age was 35.88 years old. Results We observed less thickness in all quadrants, except the nasal. The colour vision was altered in 27.77% of the patients. The contrast sensitivity test showed high frequency alterations. There was no statistically significant difference in the electroretinography test or in dark adaptation. Conclusions There are changes in the peripapillary nerve fibre layer thickness; also we found changes in colour vision, contrast sensitivity and a decreasing trend of the B wave in the electroreninogram.

Visual function evaluation in human immunodeficiency virus carriers

ObjectiveTo determine whether there are changes in the peripapillary nerve fibre layer, in colour vision, contrast sensitivity, dark adaptation and electroretinography changes in these patients who do not have infectious retinitis. MethodsWe studied 52 patients without ocular pathology; the mean age was 35.88 years old. ResultsWe observed less thickness in all quadrants, except the nasal. The colour vision was altered in 27.77% of the patients. The contrast sensitivity test showed high frequency alterations. There was no statistically significant difference in the electroretinography test or in dark adaptation. ConclusionsThere are changes in the peripapillary nerve fibre layer thickness; also we found changes in colour vision, contrast sensitivity and a decreasing trend of the B wave in the electroreninogram.

Comparison of photochromic, yellow, and clear intraocular lenses in human eyes under photopic and mesopic lighting conditions

To evaluate the results of the first blue light-filtering photochromic intraocular lens (IOL) and compare them with those of a regular yellow blue light-filtering IOL and a clear ultraviolet-filtering IOL in human eyes under various lighting conditions. Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University; Beijing Ophthalmology & Visual Sciences Key Laboratory, Beijing, China. Prospective comparative clinical study. This study evaluated eyes that had implantation of 1 of the following 3 IOLs: photochromic Aurium Matrix acrylic, model 400; yellow AF-1 (UY); or clear MC611MI. All eyes were followed for 3 months. The uncorrected (UDVA) and corrected (CDVA) distance visual acuities, contrast vision (lighting 400 lux, 30 lux, 5 lux), contrast sensitivity, color vision (Farnsworth-Munsell 100-hue test under 400 lux, 30 lux), and patient questionnaire responses were evaluated. The photochromic IOL group comprised 39 eyes; the yellow IOL group, 41 eyes; and the clear IOL group, 38 eyes. There were no significant differences between the 3 IOLs in UDVA, CDVA, contrast sensitivity, or questionnaire responses. The photochromic group had significantly better color vision than the yellow IOL group at 30 lux and better contrast vision at 5% contrast (P < .05); however, there were no significant differences between the photochromic IOL group and the clear IOL group (P > .05). The photochromic blue light-filtering IOL performed as well as the yellow and clear IOLs under photopic conditions. Under mesopic conditions, the yellow IOL gave poor color vision and contrast sensitivity.

Study on NCSFs of individual color mechanisms of human vision based on wave-front aberrations

Neural contrast sensitivity functions (NCSFs) of isolated color mechanisms are obtained based on the measurements of wave-front aberrations and isoluminant color contrast sensitivity functions (CSFs). Our study indicates that the mean NCSF and CSF of the red mechanism are higher than those of the green mechanism, respectively, while those of the blue mechanism are the lowest. However, the relative heights of the peak of NCSF and CSF between red and green mechanisms vary in subjects. There are some individuals whose peak values of NCSF and/or CSF of green mechanism are higher than that of the red mechanism. On the other hand, we find that the NCSFs and CSFs of isolated color mechanisms all exhibit the similar characteristics and variation tendency. With the statistical average, the NCSFs of the red, green and blue mechanisms are higher than the corresponding CSFs in the whole spatial frequency. The peaks of the NCSFs of isolated color mechanisms, comparing with the corresponding CSFs curves, shift toward higher spatial frequencies, especially for that of blue mechanism which has a largest shift of 3.9 c/deg.

Characteristics and New Measurement Method of NCSFs of Individual Color Mechanisms of Human Vision

We propose a new method for determining neural contrast sensitivity functions (NCSFs) of isolated color mechanisms based on the measurements of wave-front aberrations and isoluminant color contrast sensitivity functions (CSFs). Compared with the traditional method, this technique avoids the coherent noise and speckle noise, which are brought by the interference of laser beams, and has great flexibility for the measurements of NCSF of different color mechanisms. Our experiments indicate that the mean NCSF and CSF of the red mechanism are higher than those of the green mechanism, respectively, while those of the blue mechanism are the lowest. However the relative heights of the peak of NCSF and CSF between red and green mechanisms vary in subjects. There are some individuals whose peak values of NCSF and/or CSF of green mechanism are higher than that of the red mechanism. The NCSFs and CSFs of isolated color mechanisms all exhibit the similar characteristics and variation tendency. With the statistical average, the NCSFs of the red, green and blue mechanisms are higher than the corresponding CSFs in the whole spatial frequency. Compared with the corresponding CSFs curves, the peaks of the NCSFs of isolated color mechanisms shift toward higher spatial frequencies, especially for that of blue mechanism which has a largest shift of 3.9c/deg.

Normalization of generalized retinal function and progression of maculopathy after cessation of therapy in a case of severe hydroxychloroquine retinopathy with 19 years follow-up

A 40-year-old Caucasian female was first seen 20 years ago for a routine ocular screening in relation to hydroxychloroquine treatment for systemic lupus erythematosus. Her daily dose was 600 mg (or 12 mg/kg of body weight/day) of hydroxychloroquine. Three years later, she complained of mild visual loss in the right eye. Her best-corrected visual acuity was 0.9 in the right (RE) and 1.0 in the left eye (LE). In addition, she had a central scotoma (RE > LE) on automated visual field analysis (Humphrey central 30 degrees ). On fundoscopy and fluorescein angiography, the first signs of a bilateral bull's eye maculopathy were detected. A decreased Arden ratio on EOG (<1.50) was found with an accompanying decreased amplitude of the scotopic b-wave on full-field electroretinography in both eyes. Consequently, the treatment was immediately stopped. During the following years, the patient was retested regularly. After more than 18 years after cessation of the drug, most tests showed a further deterioration, including best-corrected visual acuity (RE: 0.1; LE: 0.7). On visual field testing, a progressive evolution to a total and absolute central scotoma in the RE (central 10 degrees ) and an annular scotoma in the LE became apparent. In contrast, a partial recovery of the Arden ratio of the EOG to 1.8 in both eyes was seen. In addition, a partial recovery of the scotopic b-wave full-field ERG was noted 19 years after cessation of treatment. At retest visits respectively 18, 19 and 20 years after cessation of hydroxychloroquine, a multifocal electroretinogram was performed in combination with colour vision tests and contrast sensitivity measurements.

Perceived Color of Hallucinations in the Charles Bonnet Syndrome Is Related to Residual Color Contrast Sensitivity

We sought to determine whether the change in cortical excitability secondary to deafferentation in patients with Charles Bonnet Syndrome (CBS) who hallucinate in a predominant color or combination of colors is related to an alteration in color contrast thresholds and whether the change is specific to the color of the hallucination. We prospectively categorized each patient's hallucinations using the Institute of Psychiatry Visual Hallucinations Interview. We measured color contrast thresholds with a computerized test designed to assess red-green and blue-yellow color confusion axes against a background of luminance noise. We calculated the ratio of red-green threshold to blue-yellow threshold (R-G/B-Y ratio) for each patient. Because central vision was impaired in all patients, we used a sectoral annular stimulus that projected to the retina at 12.5 degrees eccentricity. There were 10 patients with age-related macular degeneration and CBS who were hallucinating in a predominant color or combination of colors at the time of recruitment. Patients hallucinating in red, green, or a combination of red and green had R-G/B-Y ratios of less than 1.0 (n = 5). Patients hallucinating in blue, yellow, or a combination of blue and yellow had R-G/B-Y ratios of greater than 1.0 (n = 2). Patients hallucinating in purple had ratios between the red-green and blue-yellow hallucinators (n = 2). The 1 patient hallucinating in white had the lowest thresholds for red-green and blue-yellow confusion axes. Comparing the R-G/B-Y ratios for the "red/green hallucinators" and "blue/yellow hallucinators" returned a significant result with Fisher's exact test (P = 0.047, n = 7). Deafferentation and secondary cortical hyperexcitability in CBS have a correlate in psychophysical threshold. This change in sensitivity relates specifically to the hallucinated color axis rather than across all colors. This is the first published evidence for cerebral hyperexcitability leading to a decrease in color contrast thresholds.

Dynamic sensitivity of area V4 neurons during saccade preparation

During the preparation of saccadic eye movements, visual attention is confined to the target of intended fixation and there is a corresponding diminution of visual sensitivity at nontarget locations. Neurons within the macaque visual cortex exhibit correlates of these perceptual changes, such as in area V4, where neuronal responses are enhanced during the preparation of saccades to stimuli within the receptive field (RF), and responses are suppressed during the preparation of saccades to other locations. Both the perceptual and neurophysiological effects suggest that the sensitivity of visual cortical neurons to input is dynamic during saccade preparation. We probed the contrast sensitivity of area V4 neurons to nontarget stimuli at varying times during the preparation of saccades to locations outside of the neuron's receptive field. We found that the contrast sensitivity of many neurons is profoundly altered within 50 ms of saccade onset. The luminance or color contrast sensitivity of individual V4 neurons could increase, decrease, or remain unchanged before saccade onset. For luminance contrast sensitivity, decreases in sensitivity were more frequent and larger in magnitude, resulting in an overall decrement in sensitivity across the population. For color contrast, the effects were smaller and more heterogeneous, resulting in little or no overall change in sensitivity across the population. Our results demonstrate the dynamic influence that saccade preparation has on the sensitivity of visual cortical neurons and suggest a basis for the changes in perception known to occur during saccade preparation.

Occupational styrene exposure, colour vision and contrast sensitivity: a cohort study with repeated measurements

Associations between occupational styrene exposures and impairment of visual functions were investigated with a view to answering three questions: (1) are the published findings for colour vision deficiencies and impaired contrast sensitivity to reproduce in a new study approach, (2) if such effects exist, are they related to current or chronic exposures and (3) if effects exist, are there reductions in the effects during an exposure-free period? Workers from a boat building plant were examined in groups of current low [n = 97, mean mandelic acid (MA) + phenylglyoxylic acid (PGA) = 51 mg/g creatinine], medium (n = 115, mean = 229 mg/g creatinine) and high (n = 30, mean = 977 mg/g creatinine) level exposure to styrene. Job tenure was about 6 years. In addition, subgroups chronically exposed to low-short (n = 34, lifetime weighted mean 200 mg/g creatinine for 6 years) and high-long (n = 17, mean = 660 mg/g creatinine, 15 years) styrene levels were analysed. The examinations were carried out during normal working days and during the company holidays. Colour vision was investigated with the Lanthony desaturated panel D-15d using the colour confusion index (CCI) as a relevant variable. Contrast sensitivity was investigated with the Vistech charts VCTS 6500 using frequency-related results as well as total scores as variables. Co-variance analyses with repeated measurements and multiple linear regressions were used for statistical analysis. There was no evidence of significant associations between exposure parameters and CCI. This is true for the analyses with all participants as well as for those with the subgroups with high-long versus low-short exposure. Thus, no exposure related changes in the relevant variables were found during the exposure-free period. The analyses for contrast sensitivity show similar results. The largest portions of the variances in both tests were explained by age. German as mother tongue covered a considerable portion of the CCI variances. Education, long-term alcohol use and job tenure explain only partly significant portions of the test variances exhibited. Both acute styrene exposure levels of 40 ppm (range of standard deviation up to 54 ppm) and long term exposures to 27 ppm (range of standard deviation up to 44 ppm with higher exposure levels in the past) for a period of about 15 years were not identified as causing elevated risks for the investigated parameters of colour vision and contrast sensitivity. This statement contradicts the published results for styrene-related colour vision deficiencies but it seems to be compatible with published results for contrast sensitivity due to styrene exposure.

Intraindividual Comparison of Color Perception and Contrast Sensitivity with and without a Blue Light-Filtering Intraocular Lens

To investigate color perception and contrast sensitivity with and without additional glare in pseudophakic patients with a conventional intraocular lens (IOL) in one eye and a blue light-filtering IOL in the fellow eye. Twenty-three bilaterally pseudophakic patients with a conventional IOL (AcrySof SA60AT) and a blue light-filtering IOL (AcrySof Natural SN60AT) were tested for intraindividual comparison of visual acuity (ETDRS chart), color perception (Farnsworth-Munsell 100-Hue test), and contrast sensitivity with and without glare (Contrast Sensitivity Pattern Generator). Information about subjective perception was gathered through a questionnaire. Four patients (17.4%) observed some difference in monocular color perception. Color testing did not show significantly different results for the two IOL types expressed as total error score and segmental error subscores for protan, deutan, and tritan ranges. Regarding contrast sensitivity, 5 patients (21.7%) indicated noticeable difference between the two eyes. Contrast sensitivity testing, however, showed similar curves for the two IOL types with and without additional glare. Despite some subjective difference in color and contrast perception in a minority of patients, the study did not show significantly different results for the two IOL types.

An investigation of the visual disturbances experienced by patients on clomiphene citrate

To evaluate the impact of clomiphene citrate on vision. Observational study. Patients were referred to the University of Ottawa Eye Institute ophthalmology clinic from the Department of Obstetrics and Gynaecology of the Ottawa Hospital-General Campus. Eight adult females taking clomiphene citrate and experiencing visual disturbances. Patients received a comprehensive visual evaluation twice: once during a washout period, and once during an active clomiphene citrate treatment. Ophthalmologic examination, color vision, visual acuity, contrast sensitivity, visual fields using standard automated perimetry, and foveal flicker sensitivity at high (32 Hz) and low (8 Hz) temporal frequencies. We found no differences between the washout and clomiphene citrate conditions for color vision, visual acuity, contrast sensitivity, and visual fields. The only statistically significant difference was found for foveal flicker sensitivity at 32 Hz in the right eye, with a similar trend in the left eye and at 8 Hz in both eyes. The effect of clomiphene citrate on vision was minimal, and the visual disturbances were reversible in all patients. A bilateral reduction in flicker sensitivity was the only observed visual disturbance. Women who experience visual symptoms associated with clomiphene citrate should be monitored, but therapy can usually be maintained.

Fellow-eye comparison of posterior capsule opacification with AcrySof SN60AT and AF-1 YA-60BB blue-blocking intraocular lenses

To evaluate intraindividual differences in posterior capsule opacification (PCO) and visual performance of AcrySof SN60AT (Alcon Laboratories) and AF-1 YA-60BB (Hoya Corp.) intraocular lenses (IOLs). Ophthalmology Department, St. Thomas' Hospital, London, United Kingdom. In this prospective single-surgeon standardized-surgical-procedure fellow-eye comparison, an AcrySof SN60AT or an AF-1 YA-60BB IOL was randomized to the first eye of 36 patients and fellow-eye surgery was performed within 4 to 6 weeks. Follow-up was at 1, 3, 6, 12, and 24 months. Best distance- corrected logMAR visual acuity was measured at 100% and 9% contrast. Contrast sensitivity was measured using the Functional Acuity Contrast Test (FACT) on the Optec 3500 instrument (Stereo Optical Company, Inc.). Color vision was assessed with the Farnsworth Munsell 100-hue test. After pupil dilation, digital retroillumination photographs were taken and the percentage area of PCO was calculated using POCO software. Posterior capsule opacification was significantly greater in the AF-1 YA-60BB group than in the AcrySof SN60AT group at all time points (P<.0001), with the difference greatest at 24 months. At 24 months, 100% contrast visual acuity was significantly better in the AcrySof SN60AT group than in the AF-1 YA-60BB group (P = .0313); 9% contrast visual acuity was significantly better in the AcrySof SN60AT group from 6 months onward. There was no significant difference between groups in color vision or contrast sensitivity. Electron microscopy showed the AcrySof SN60AT IOL has a much sharper posterior edge profile. The AcrySof SN60AT IOL had better PCO performance and thus visual performance than the AF-1 YA-60BB IOL. This is attributable to the differences in optic edge design.

The ChromaTest, a digital color contrast sensitivity analyzer, for diabetic maculopathy: a pilot study

BackgroundTo assess the ability of the Chromatest in investigating diabetic maculopathy.MethodPatients with Type 2 diabetes and no concurrent ocular pathology or previous laser photocoagulation were recruited. Visual acuities were assessed followed by colour contrast sensitivity testing of each eye using Chromatest. Dilated fundoscopy with slit lamp biomicroscopy with 78 D lens was then performed to confirm the stage of diabetic retinopathy according to the Early Treatment Diabetic Retinopathy Study.Results150 eyes in 150 patients were recruited into this study. 35 eyes with no previous laser photocoagulation were shown to have clinically significant macular oedema (CSMO) and 115 eyes with untreated non-proliferative diabetic retinopathy (NPDR) on fundus biomicroscopy. Statistical significant difference was found between CSMO and NPDR eyes for protan colour contrast threshold (p = 0.01). Statistical significance was found between CSMO and NPDR eyes for tritan colour contrast threshold (p = 0.0002). Sensitivity and specificity for screening of CSMO using pass-fail criterion for age matched TCCT results achieved 71% (95% confidence interval: 53–85%) and 70% (95% confidence interval: 60–78%), respectively. However, threshold levels were derived using the same data set for both training and testing the effectiveness since this was the first study of NPDR using the ChromatestConclusionThe ChromaTest is a simple, cheap, easy to use, and quick test for colour contrast sensitivity. This study did not achieve results to justify use of the Chromatest for screening, but it reinforced the changes seen in tritan colour vision in diabetic retinopathy.

Intraindividual comparison of color contrast sensitivity in patients with clear and blue-light-filtering intraocular lenses

To evaluate the effect of blue-light-filtering intraocular lenses (IOLs) with a yellow chromophore on color contrast sensitivity by intraindividual comparison with an identically designed IOL without a blue-light filter. Medical University of Vienna, Department of Ophthalmology, Vienna, Austria. Randomized implantation of an AF-1 (UV) IOL (Hoya) in 1 eye and an AF-1 (UY) IOL (Hoya) in the contralateral eye was performed after phacoemulsification and primary posterior curvilinear capsulorhexis. Three months postoperatively, the best distance-corrected visual acuity was evaluated. Before color contrast sensitivity testing, a heterochromatic flicker test was performed in both eyes to avoid error in brightness matching. Central and peripheral tritan color contrast sensitivities were evaluated using the Moorfields Vision System (CH Electronics). Visual acuity did not differ significantly between the 2 IOL groups (P>.05). The central color contrast sensitivity threshold also did not differ significantly between eyes with a clear IOL and eyes with a yellow IOL at any tested spatial frequency. The peripheral color contrast sensitivity test showed slightly higher color contrast sensitivity thresholds in eyes with a yellow IOL, although the differences were not statistically significant. Two patients independently reported subjective changes in color perception in the eye with the yellow IOL. In this intraindividual comparison, the implantation of a blue-light-filtering IOL did not lead to a clinically significant change in color contrast sensitivity.

The Evaluation of Yellow vs. Blue Color Contrast Sensitivity pre and Post LASIK

Introduction: contrast sensitivity is one of the most important psychophysical tests that may be used for the evaluation of refractive state of eye and retinal image quality. Yellow vs. blue color contrast sensitivity may be more suitable in this regard. Materials and Methods: thirty myopic eyes were considered in this study. Yellow vs. blue color contrast sensitivity was evaluated under the same environment and conditions in these individuals pre and post LASIK. Results: The comparison of yellow vs. blue color contrast sensitivity with glasses pr e and post LASIK shows a significant improvement (p<0.001) in the contrast sensitivity. Discussion and Conclusion: The improvement of optical state of the eye is the main reason for the improvement of contrast sensitivity. The reason behind performing LASIK surgery and surgeon's experience on one hand, and the undesirable quality of glasses due to the lack of standard in the manufacturing and glazing of correcting lenses on the other hand are the main factors behind the improvement of optical state of the eye.

Differential Changes of Magnocellular and Parvocellular Visual Function in Early- and Late-Onset Strabismic Amblyopia

Studies in nonhuman primates show that monocular visual deprivation starting at different ages has different effects on cells in the parvocellular and magnocellular laminae of the lateral geniculate nucleus. The present study used color and luminance contrast sensitivity (CS) measurements to look for differences in parvocellular- and magnocellular-related visual function in human subjects with strabismic amblyopia. Fifteen subjects with early- and 14 with late-onset strabismic amblyopia and similar ranges of visual acuity were studied, together with 15 subjects with normal vision. Contrast sensitivities were measured to an equiluminant (L-M cone-modulated) grating with slow onset and an achromatic (L+M cone-modulated) 0.8-cpd grating with rapid onset using an adaptive Luminance and color CS were lower in the amblyopic eyes than in the fellow eyes of all amblyopes. For luminance CS, this was due both to an increase in sensitivity of the fellow eye and to a reduction in sensitivity in the amblyopic eye. Color CS was greatly reduced in the amblyopic and fellow eyes of subjects with strabismic amblyopia of early- and late onset compared with subjects with normal vision. The reduction in color CS compared with luminance CS was significantly greater in eyes with late- rather than early-onset amblyopia. Parvocellular and magnocellular function are differentially affected in the amblyopic and fellow eyes of subjects with strabismic amblyopia. The difference is more marked in late-onset amblyopia than in early-onset amblyopia.