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PubMed2002

Individual differences in chromatic (red/green) contrast sensitivity are constrained by the relative number of L- versus M-cones in the eye.

Many previous studies have shown that the relative number of long-wavelength-selective (L) versus medium-wavelength-selective (M) cones in the eye influences spectral sensitivity revealed perceptually. Here, we hypothesize that the L:M cone ratio should also influence red/green chromatic contrast sensitivity. To test this, in each subject we derived an estimate of L:M ratio based on her red/green equiluminance settings (obtained with heterochromatic flicker photometry), and measured both red/green chromatic and luminance contrast sensitivity at different spatial and temporal frequencies. Factor analysis was applied to the data in order to reveal covariance between conditions. As expected, chromatic and luminance contrast sensitivity were found to be independent of one another, and no relationship was observed between L:M ratio and luminance contrast sensitivity. However, a significant relationship was observed between L:M ratio and chromatic contrast sensitivity, wherein subjects possessing the most symmetrical L:M cone ratios (i.e., near 1:1) appear to possess the relatively greatest chromatic contrast sensitivity. This relationship can be accounted for by a simple model based on the notion of random L- and M-cone inputs to the center and surround receptive fields of chromatic (L-M) mechanisms.

Adolescent↗
PubMed1991

Inhibition of binocular contrast sensitivity in hypermetropic anisometropia.

Binocular contrast inhibition can occur when the monocular contrast sensitivities are not equal. It has been reported in cases of monocular cataracts. Our case is an 18-year-old female with 3.50 D of hypermetropic anisometropia. She was not amblyopic but showed a typical binocular contrast inhibition.

Adolescent↗
PubMed2001

Contrast sensitivity function in children: normalized notation for the assessment and diagnosis of diseases.

The purpose of this article is to describe a normalized notation for the assessment of the contrast sensitivity in children. This notation is obtained dividing the log contrast sensitivity value found in a patient by the corresponding normative contrast sensitivity data. The ratio obtained describes the contrast sensitivity of a patient facilitating its understanding, assessment and consequently effective communications. This article shows the normalized notation developed for children aged from 3 to 7 years old. An evaluation of the contrast sensitivity in healthy and amblyopic patients has been shown in order to explain the procedure to follow. The use of normalized notation in clinical procedures will provide to the clinician a better understanding of the results and the changes over time as well by comparison in the assessment of an ocular disease.

Amblyopia↗
PubMed1990

[Contrast sensitivity of the pseudophakic eye].

Contrast sensitivity in pseudophacic eye show normal recuperation except in case of macular oedema. Decrease of responses in low spatial frequencies is observed; the same as in minor veinous occlusion.

Cataract↗
PubMedDate not supplied

Measuring contrast sensitivity in aretinopathic patients with Insulin Dependent Diabetes Mellitus.

Contrast sensitivity measurements were obtained from 66 patients with Insulin Dependent Diabetes Mellitus (IDDM) and no visible diabetic retinopathy (Group A, n = 30 prepubescent and pubescent subjects; Group B, n = 36 postpubescent subjects). Contrast thresholds were determined for stationary and 6.87 Hz phase-alternating gratings at eight spatial frequencies from 0.18 to 15.7 c/deg. Data from each group of diabetic patients was compared with data from puberty-matched normal subjects. Mean value of the last four determinations of glycohemoglobin Alc (HbAlc) was used as a index of glycemic control. We found that patients with IDDM and no retinopathy had normal contrast sensitivity and that contrast thresholds were not significantly related to sexual maturity, duration of diabetes and glycemic control.

Adolescent↗
PubMed2004

Comparing the contrast sensitivity of a modified prolate anterior surface IOL and of two spherical IOLs.

PURPOSE: To compare the contrast sensitivity of an intraocular lens (IOL) with a modified prolate anterior surface (Tecnis Z9000, Pfizer), with 2 standard spherical IOLs (Sensar AR40e Opti-Edge IOL, AMO and AcrySof Natural SN60AT IOL, Alcon). METHODS: In this prospective study, 98 eyes of 71 patients received 1 of 3 IOLs at random. After 6 months, best corrected visual acuity, pupil size and contrast sensitivity under mesopic and photopic conditions were measured. RESULTS: No statistically significant differences in preoperative and postoperative refractive error and best corrected visual acuity existed between the groups. When comparing the Tecnis IOL with the AR40e IOL, contrast sensitivity testing showed significantly better results in the Tecnis group at 3 and 12 cpd in photopic conditions; at 3, 12 and 18 cpd in photopic with glare; at 3, 12 and 18 cpd in mesopic and at 12 and 18 cpd in mesopic with glare. The Tecnis IOL provided significantly better contrast sensitivity at almost all spatial frequencies in any lighting condition in comparison with the SN60AT IOL. CONCLUSION: Implantation of a modified prolate IOL may improve quality of vision as demonstrated by our clinical results of contrast sensitivity testing. In this study, we found a better performance of the Tecnis IOL under both photopic and mesopic conditions, compared to the results of the AR40e and the SN60AT IOL.

Aged↗
PubMedDate not supplied

[An estimation of the contrast sensitivity of kittens after termination of the critical developmental period].

Special contrast sensitivity was estimated in kittens at the age of 6, 9 and 12 months as well as in adult cats. Acuteness of perception of grating pattern remained the same in kittens of 6 as well as 12 months of age. However, the former kittens were shown to have a decreased contrast sensitivity at lower spatial frequencies (cycles/degree). The contrast sensitivity reached the adult level at 12-month age. This seems to reflect a maturation of the higher cortical areas involved in the recognition process.

Aging↗
PubMed1996

Contrast sensitivity in different types of early lens opacities.

The purpose of the present study was to evaluate the relationship of various types of early lens opacities with contrast sensitivity at different spatial frequencies. The Lens Opacities Classification System II and Lensmeter 701 were used in the grading of the lens status. The contrast sensitivity was tested with the Vistech VCTS 6500 distance test with optimal correction of refractive errors. Data from 995 eyes were available for the present study. Contrast sensitivity decreased by increasing lens opacification graded with the Lens Opacities Classification System II and also by increasing Lensmeter 701 reading. When the statistical model was adjusted for age and best corrected visual acuity, nuclear opacities and nuclear colour were not associated with decreased contrast sensitivity, however, there was a weak, but statistically significant correlation between contrast sensitivity reduction and cortical opacities at high spatial frequencies, and between contrast sensitivity and posterior subcapsular opacities at low and medium spatial frequencies.

Adult↗
PubMed2003

Is binocular contrast sensitivity at distance compromised with multifocal soft contact lenses used to correct presbyopia?

PURPOSE: The purpose of this investigation was to determine whether new experimental multifocal optical designs incorporating diffractive/refractive optics for correction of presbyopia in a soft contact lens would compromise binocular contrast sensitivity at distance while achieving 20/20 binocular visual acuity at near. METHODS: Thirty presbyopic volunteers were fitted with Acuvue Bifocal soft lenses, two (FO1 and 3B1) experimental diffractive/refractive multifocal soft lenses separately and in combination as a pair and soft spherical lenses. Visual performance was evaluated via binocular contrast sensitivity and binocular distance high- and low-contrast visual acuity after 1 week of lens wear. RESULTS: The experimental lenses FO1 and the combination FO1/3B1 performed as well for binocular contrast sensitivity, binocular distance high-contrast visual acuity, and binocular distance low-contrast visual acuity as the habitual presbyopic correction and the spherical soft distance correction. A strong correlation (r = 0.73 and 0.53, respectively) was found between binocular contrast sensitivity and binocular distance low-contrast visual acuity with experimental FO1 and FO1/3B1 lenses. However, the correlation (r = 0.37 and 0.60, respectively) between binocular contrast sensitivity and binocular distance high- and low-contrast visual acuity with FO1 was weaker than that with the combination FO1/3B1 lenses. Subjective responses support the objective data. DISCUSSION: The data show that experimental FO1 lens and the experimental combination of the FO1/3B1 lenses can be prescribed to not compromise distance binocular contrast sensitivity.

Adult↗
PubMed1998

Contrast sensitivity in obese dyslipidemic patients with insulin resistance.

OBJECTIVE: To evaluate contrast sensitivity in insulin-resistant obese patients and in aretinopathic diabetic patients. METHODS: Contrast sensitivity was measured at 3 letter sizes (44 x 44, 9 x 9, and 5 x 5 mm) in mesopic (5 candela [cd]/m2) and low photopic (85 cd/m2) vision in 20 dyslipidemic obese patients with insulin resistance, 20 age-matched patients with type 2 diabetes mellitus, and 20 aged-matched healthy control subjects. RESULTS: Significant loss of contrast sensitivity at all 3 letter sizes was observed in low photopic vision (at 44 x 44-mm letter size, control vs obese, P<.002, and control vs diabetic, P<.005; at 9 x 9-mm letter size, control vs obese, P<.02, and control vs diabetic, P<.001; and at 5 x 5-mm letter size, control vs obese, P<.05, and control vs diabetic, P<.005) and mesopic vision (at 44 x 44-mm letter size, control vs diabetic, P<.005; at 9 x 9-mm letter size, control vs obese, P<.005, and control vs diabetic, P<.01; and at 5 x 5-mm letter size, control vs obese, P<.005, and control vs diabetic, P<.001) in insulin-resistant obese and diabetic patients. CONCLUSION: The results suggest that an early neurosensory dysfunction may occur without visible vascular involvement and without overt hyperglycemia.

Adult↗
PubMed1988

Spatial brightness contrast sensitivity measured with white, green, red and blue light.

Grating contrast sensitivity was measured using different colors and different grating orientations. The contrast sensitivity was highest when measured with green light, a little less when measured with red light, and lowest with blue light. The contrast sensitivity with blue light was relatively low compared with green and red light for high spatial frequencies, and relatively high for low spatial sensitivities. The so-called 'oblique effect' was confirmed in this study, but a difference between horizontal and oblique gratings was only found in spatial frequencies higher than 18 cycles/degree. The present study, carried out on 20 persons, suggests that the inter- and intraindividual components of variance are smallest when measured with green light and vertically oriented gratings.

Adolescent↗
PubMed2006

Contrast sensitivity: determining the visual quality and function of cataract, intraocular lenses and refractive surgery.

PURPOSE OF REVIEW: This review provides an update of recent advances in understanding the quality and functional significance of contrast sensitivity for the clinician regarding cataract, intraocular lenses and refractive surgery that goes beyond the measurement of visual acuity. RECENT FINDINGS: New American National Standards Institute standards for contrast sensitivity based on linear sine-wave gratings are discussed that promise rapid advances of understanding and quantifying visual quality and function by unifying clinical results reported using contrast sensitivity. Increased sensitivity of linear sine-wave gratings over proposed bull's-eye radial gratings is discussed. Digital-image-processing software uses contrast sensitivity data to process images to help understand the quality of what the patient sees. Contrast sensitivity measurement is compared with wavefront aberrometry. Contrast sensitivity measures the total visual system quality in terms of contrast, whereas wavefront aberrometry measures the optical quality in terms of spatial distortion. Both measurements are needed to more fully understand the quality of vision. SUMMARY: Recent advances provide the clinician with an awareness of why the new contrast-sensitivity standards are based on linear sine-wave gratings and how image-processing software can be used to better understand the quality of functional vision of the patient.

Cataract↗
PubMed1990

[Value of a study of contrast sensitivity in the evaluation of visual function: applications to pathology and visual selection].

Spatial contrast sensitivity function appears to give the most general description available for the basic aspect of spatial visual performance. Classical measurement of visual acuity is unable to give us a fine appreciation of visual function. Visual acuity is only one aspect of the complex process of sight. We have tested contrast sensitivity to detect silent lesions of the visual pathway. In multiple sclerosis we have demonstrated a bilateral involvement in almost all cases. In primary open angle glaucoma contrast sensitivity is affected before perimetry data are able to show any defect. We have the same results in early stages of diabetic retinopathy. Contrast sensitivity testing shows great promise for detection of eye defect in drivers and industry workmen.

Contrast Sensitivity↗
PubMed1986

Contrast sensitivity versus visual acuity in retinal disease.

A large group of individuals with retinal disease were tested prospectively for contrast sensitivity by means of Arden gratings. A subgroup of 19 were also tested with the Nicolet automated television system. Individuals with macular or peripheral dystrophy showed a general reduction in contrast sensitivity as visual acuity decreased. The loss of contrast sensitivity was more prominent for high spatial frequencies (6.4 cycles per degree) than for low ones (0.2 cycles per degree). Similar results were obtained for patients with achromatopsia and congenital stationary night blindness. Patients with functional complaints, but no organic basis for decreased acuity, showed greater scatter in their test scores. The Nicolet results showed somewhat smoother curves, but were no more specific in separating normality from abnormality. Contrast sensitivity testing was not specific for the retinal disease entities considered, but may be useful in recording a degree of retinal damage and a degree of functional visual disability. Contrast sensitivity appeared to be reduced whenever acuity was reduced, so that a distinction could be made between patients having a loss of contrast beyond the expectations for their level of acuity and those in whom a loss of contrast simply corroborates the reduction of acuity.

Adolescent↗
PubMed1993

Relative contributions of optical and neural limitations to human contrast sensitivity at different luminance levels.

The relative contributions of optical and neural constraints on human contrast sensitivity as a function of spatial frequency were assessed for a range of luminances. First, the overall two-dimensional contrast sensitivity function (CSF) was obtained for three eyes at three luminances (0.05, 0.5 and 20 cd/m2) using a standard two-alternative forced-choice procedure. Second, the two-dimensional modulation transfer function (MTF) of the optics was measured for the same eyes and pupil sizes using a hybrid optical-digital method. The two-dimensional neural transfer function (NTF) was obtained as the ratio between the CSF and the MTF. Minor factors, such as the effect of cone aperture, were also considered in the computations. Our results show that at all luminances, the fall off in contrast sensitivity at high spatial frequencies is mainly due to optical factors. The losses in contrast sensitivity with decreasing luminance are, however, primarily due to noise limitations.

Contrast Sensitivity↗
PubMed2006

Visual acuity, contrast sensitivity, and mortality in older women: Study of osteoporotic fractures.

OBJECTIVES: To determine whether poorer visual acuity and contrast sensitivity are independent risk factors for all-cause and traumatic mortality in older women. DESIGN: Twelve-year prospective cohort study (1986-2003). SETTING: Four U.S. clinical centers. PARTICIPANTS: Nine thousand seven hundred four postmenopausal white women aged 65 and older. MEASUREMENTS: Habitually corrected binocular visual acuity and low- and high-frequency contrast sensitivity were measured at baseline using a standard protocol. A study physician adjudicated the primary cause of death from death certificates and medical record review. RESULTS: During an average of 12.2 years of follow-up, 3,427 women died (35%), 72 (0.7%) from traumatic events. In multivariate models adjusted for age, chronic medical problems, and smoking, all-cause mortality risk was 19% greater for persons in the worst quartile of visual acuity than for those in the best (hazard ratio (HR) = 1.19, P = .008) and 39% greater for persons with the worst contrast sensitivity (HR = 1.39, P < .001) than for those with the best. Traumatic mortality risk was 2.4 times greater for women with the worst contrast sensitivity than for those with the best (HR = 2.44, P = .03). CONCLUSION: Poorer visual acuity and contrast sensitivity are associated with greater risk of traumatic and all-cause mortality in older women, even after controlling for demographic and clinical characteristics. Although further research is necessary to determine how treating reversible causes of visual impairment or improving current refraction affects mortality in older women, clinical detection and follow-up of these visual impairments holds promise for identifying those who are at risk of mortality from other systemic conditions.

Aged↗
PubMedDate not supplied

Correlation of wavefront data and corneal asphericity with contrast sensitivity after laser in situ keratomileusis for myopia.

PURPOSE: To investigate the relationship between contrast sensitivity (CS), Zernike wavefront aberrations (WFA), and asphericity after laser in situ keratomileusis (LASIK) for myopia. METHODS: LASIK was performed using the Nidek EC-5000 excimer laser with custom aspheric transition zone (CATz) ablations. Total and high order (HO) WFA of 71 eyes (37 patients) undergoing LASIK in March 2003 were measured before and at 1 month postoperatively with the Nidek OPD-Scan aberrometer at a 4-mm pupil entrance; asphericity was measured at 6 mm (Q index). Preoperative and 1 to 3-month postoperative contrast sensitivity were evaluated with the Vector Vision CSV-1000 at 3, 6, 12, and 18 CPD; the Area Under the Log Contrast Sensitivity Function (AULCSF) was calculated. Uncorrected-visual acuity (UCVA) was evaluated. RESULTS: One month after LASIK, CS decreased significantly at 6 CPD and above (P<.05), then returned to normal at 3 months (P=.33). Postoperative AULCSF correlated with patient age (P=.04) but not with total WFA (P=.13), HO WFA (P=.50), or asphericity (P=.22). Postoperative Logmar UCVA correlated with postoperative total and HO WFA (P<.05). Postoperative total WFA correlated with spherical equivalent refraction (P<.0001); HO WFA correlated with Strehl ratio (P=.004) and asphericity (P=.03). The HO WFA increase was 0.065 microm (P<.05) and did not correlate with preoperative refraction (P=.40). Increase in asphericity correlated with corneal refractive change and was predicted by the parabolic Munnerlyn equation (P<.0001). CONCLUSIONS: After LASIK, AULCSF was not dependent on WFA, but mainly on patient age. WFA results correlated well with postoperative spherical equivalent refraction, asphericity, and Strehl ratio. These conclusions support a published hypothesis that postoperative low amount of WFA does not completely fit contrast sensitivity measurements.

Adult↗
PubMed1991

Association of Vistech contrast sensitivity and visual field findings in glaucoma.

Single eye visual fields and contrast sensitivity were assessed in 60 subjects, who were being followed up in a glaucoma clinic for manifest glaucoma or a suspicion of glaucoma because of raised intraocular pressure. The Fieldmaster 5000 (static/kinetic perimeter) was used for the visual fields, and a Vistech wall chart sine wave grating test was used for contrast sensitivity measurements. The subjects were divided into three groups--defect (D), suspect (S) and normal (N)--on the basis of their perimetric findings by subjective grading of 16 perimetric scoring categories for each visual field. The mean Vistech sensitivity levels were not found to be significantly different between the D, S, and N field subgroups at any of the five spatial frequencies provided on the test charts (1.5, 3, 6, 12, and 18 cycles per degree). Complex algorithms combining results from two or more spatial frequencies also failed to yield any significant differences between the groups. Diagnostic sensitivity and specificities relating Vistech contrast sensitivity findings to groups N and D never concomitantly exceeded 60%.

Adult↗