جستجوی مقالات مرتبط با کلیدواژه « contrast sensitivity » در نشریات گروه « پزشکی »

To determine the relationship between road accidents with visual acuity, refractive errors, visual field, and contrast sensitivity.

This population-based case–control study was conducted on roads leading to Tehran Province, Iran. The case group comprised drivers who had met with accidents and were at fault for the accident. The cases were selected in an ongoing manner (incidence cases). The controls were drivers who were the opposing victims in the same. After an initial interview, optometric and ophthalmic examinations including the measurement of visual acuity, refraction, visual field assessment, contrast sensitivity measurement, and slit lamp biomicroscopy were performed for all study participants.

In this study, 281 and 204 individuals were selected for the case and control groups. The mean uncorrected visual acuity was 0.05 ± 0.12 and 0.037 ± 0.10 logMAR in the case and control groups, respectively (P = 0.095). Of the participants in the case and control groups, 32.8% and 23% had a visual field defect in at least one eye, respectively (adjusted odds ratios [aOR] = 1.63, 95% confidence interval [CI]: 1.08–2.48; P = 0.021). Moreover, 16.2% of the cases and 8.3% of the controls had visual field defects in both eyes (aOR = 2.13, 95% CI: 1.17–3.86; P = 0.012). Contrast sensitivity was worse in the case group in all spatial frequencies under non-glare conditions. However, under glare conditions, the contrast sensitivity was significantly worse in the case group only in the spatial frequency of 12 cycles per degree (cpd).

Reduced contrast sensitivity, especially under non-glare conditions, and visual field defects are risk factors that influence the prevalence of road accidents. It is strongly advised that special attention be paid to these visual functions in legal assessments to apply the necessary interventions in individuals with these types of disorders.

To assess the agreement between two different contrast testing modalities using the index of contrast sensitivity (ICS) in patients with low vision.

Thirty‑eight patients with low vision were included in the study. Contrast sensitivity (CS) was measured binocularly with both the Vector vision‑standardized CS test (CSV‑1000E, Vector Vision Co, Greenville, Ohio, USA) and the MonPack 3 (Metrovision, France) after refractive correction for each participant. Based on the data from the two tests, the ICS was calculated. The Bland–Altman technique was used to evaluate the agreement between ICSs obtained from different test methods.

Range of best corrected visual acuity was 0.50–1.00 logMAR. According to the median logCS values, CS values were highest at 3 cycles per degree (cpd) for the CSV‑1000E test and at 1.5 cpd for the Metrovision MonPack 3 test. The median ICS for CSV‑1000E was −0.22 (95th percentile 4.75), and the median ICS for Metrovision MonPack 3 was 0.08 (95th percentile 1.65). The mean difference was 0.655 (between −3.82 and 5.13) within limits of agreement (LoA). The difference and mean values between the two CS test measurements were found to be within LoA range.

An agreement was found between the Metrovision MonPack 3 test and the standard CSV‑1000E test results in patients with visual impairment. However, the agreement range was within very wide limits. Therefore, it was thought that they may not be used interchangeability in clinical practice.

This study aimed to evaluate the distribution of contrast sensitivity (CS) using Pelli Robson test in normal individuals over seven years old living in Zahedan and examine its relationship with age, gender, and refractive errors.

In this cross-sectional study, simple sampling was performed on the patients aged over seven years and their attendants who had referred to Al-Zahra eye hospital in Zahedan. Complete ophthalmic examinations including vision and refraction assessment, biomicroscopy, and CS evaluation were carried out for all subjects. To evaluate CS, Pelli Robson chart was used at a distance of one meter. The logarithmic CS value of the last triplet in which the patient could accurately read two words was regarded as his/her CS value.

Of the 150 patients (300 eyes), 70 (46.66%) were male. The mean age of the subjects was 34.56±16.15 years (ranged from seven to 78 years). The mean and standard deviation of the CS score in two modes of monocular and binocular vision were 1.45±0.19 and 1.57±0.19 log unit, respectively. The mean CS score was not significantly different between men and women (P>0.454), but it decreased significantly with the age (P=0.000). CS was higher in individuals with emmetropia than those with myopia and hypermetropia (P=0.000). There was also a significant correlation between cylinder magnitude and CS (P=0.000).

Although Pelli Robson test evaluates CS at low and constant spatial frequencies, its distribution is significantly different among different age groups and even among individuals with different values of refractive errors.

To assess contrast sensitivity in clear and colored soft contact lenses under different lighting conditions.

This study was performed on 34 medical students. Visual acuity was measured using a tumbling E chart at a distance of 6 m, and contrast sensitivity was determined by Pelli Robson chart at a distance of 1 m. These tests were repeated in mesopic (3 lux) and glare (2000 lux) conditions. Then, a clear contact lens was applied to one eye and a colored contact lens was applied to the other. After 2 hr, visual acuity and contrast sensitivity were measured for each individual. The results were compared with and without contact lenses under normal, mesopic, and glare conditions.

The mean refractive error was 0.44 ± 0.20 diopters. Repeated measures ANOVA showed a decline in contrast sensitivity with colored and clear contact lenses as compared to no-lens condition (P < 0.001). Additionally, lighting conditions had a significant impact on contrast sensitivity (P < 0.001); contrast sensitivity was lower in mesopic and glare conditions than under normal lighting condition.

In addition to the drop in contrast sensitivity under unusual lighting conditions (e.g., glare and mesopic), wearing soft contact lenses can further reduce contrast sensitivity in different lighting conditions. Therefore, people who wear contact lenses should be aware of this reduction in visual performance in conditions like driving at night or in the fog.

 Binocular summation occurs in the presence of normal visual function of both eyes. Stereopsis is considered to be the finest function of binocular vision. Therefore, the aim of this study was to investigate the effect of binocular summation on contrast sensitivity and its relationship with stereopsis.

 In this cross-sectional study, 60 students of Zahedan University of Medical Sciences, Zahedan, Iran (17 men and 43 women) with a mean age of 21.20 ± 1.45 years were selected by convenience sampling method. Monocular and binocular contrast sensitivity were measured with the best corrected vision in photopic conditions using the Metrovision test for spatial frequencies of 0.75, 1.75, 3, 6, 13, and 20 cycles per degree. Stereopsis was also measured by TNO and Titmus tests. Statistical analysis was performed using the repeated measures analysis of variance (ANOVA) and multiple linear regression.

 The results of repeated measures ANOVA showed that binocular vision compared to monocular vision significantly increased contrast sensitivity (P < 0.001). But there was no significant difference between the contrast sensitivity of right and left eyes (P = 0.266). Pearson corralation test did not show a significant relationship between stereopsis measured by crossed and uncrossed methods in Titmus and TNO tests with binocular contrast sensitivity at all spatial frequencies (P = 0.114).

 Binocular summation in presence of normal binocular function can improve visual functions such as the increased binocular contrast sensitivity compared to monocular contrast sensitivity which confirms the importance of treating binocular anomalies such as amblyopia.

To evaluate the effect of asphericity and blue light filter (BLF) of three different intraocular lenses (IOLs) on the visual performance, second- and third-order aberrations (defocus, coma, trefoil), and contrast sensitivity after uneventful cataract surgery.

One hundred and twenty eyes of 60 patients with clinically significant cataract were randomly assigned to receive one of the three IOL types: Bioline Yellow Accurate (aspheric, with BLF, i-medical, Germany), BioAcryl 60125 (spherical, without BLF, Biotech, France), and H65C/N (aspheric, without BLF, PhysIOL, Belgium). Each IOL was implanted in 40 eyes. Complete ophthalmologic examination, functional acuity contrast testing and wavefront analysis were performed 60 days postoperatively.

The mean postoperative best-corrected visual acuity (BCVA) was 0.95 ± 0.08, not differing statistically among the IOL groups (P = 0.83). Mean defocus and coma values did not yield any statistically significant difference through the IOL groups varying from –0.784 to –0.614 μm and 0.129 to 0.198 μm (P = 0.79 and 0.34, respectively). Bioline Yellow Accurate IOL presented less trefoil aberrations, 0.108 ± 0.05 μm, compared to the other two IOL types (BioAcryl [0.206 ± 0.19 μm] and Physiol [0.193 ± 0.17 μm], P < 0.05). Contrast sensitivity values did not differ among the groups under all lighting conditions. Bioline Yellow IOL showed a statistically higher loss of contrast sensitivity (between mesopic and mesopic with glare conditions) compared to the BioAcryl and PhysIOL in 12 and 3 cpd spatial frequencies, respectively (P < 0.05).

Bioline Yellow IOL indicated lower contrast sensitivity under mesopic conditions when glare was applied but resulted in less trefoil aberrations after uneventful cataract surgery. No further differences were noted in postoperative visual performance among three IOL groups.

To compare the short-term visual function results and safety of erythropoietin as an add-on to the standard corticosteroid therapy in retrobulbar optic neuritis (RON).

In this prospective pilot study, adult patients with isolated RON with less than 10 days of onset were enrolled. Patients were consecutively assigned to standard intravenous methylprednisolone treatment either in combination with intravenous erythropoietin (20,000 units/day for three days) (group-1) or intravenous methylprednisolone alone (group-2). Primary outcome measure was best-corrected visual acuity (BCVA), which was assessed up to 120 days from the day the treatment was begun. Systemic evaluations were performed during and after treatment.

Sixty-two patients with RON (mean age = 26.6 ± 5.77 years; range = 18–40 years) were enrolled into the study (group-1, 𝑛 = 35; group-2, 𝑛 = 27). BCVA three months after the treatment was 0.19 ± 0.55 logMAR and 0.11 ± 0.32 logMAR in group-1 and group-2, respectively (95% CI: −0.61 − 0.16; 𝑃 = 0.62). Change in BCVA after three months was 2.84 ± 3.49 logMAR in group-1 and 2.46 ± 1.40 logMAR in group-2 (95% CI: −0.93−1.91; 𝑃 = 0.57). Pace of recovery was not significantly different between the groups. No complications were detected among patients.

Intravenous erythropoietin as an add-on did not significantly improve the visual outcome in terms of visual acuity, visual field, and contrast sensitivity compared to traditional intravenous corticosteroid. This pilot study supports the safety profile of intravenous human recombinant erythropoietin, and it may help formulate future investigations with a larger sample size.

To evaluate the effect of fasting on contrast sensitivity (CS) in healthy male individuals during the month of Ramadan.

This study included 45 healthy male individuals, aged between 20 and 40 years, working in the same environment. Functional acuity contrast testing (F.A.C.T) was performed using the Optec 6500 vision testing system. Measurements taken during a state of satiety one week before Ramadan were compared with those taken a minimum of 12 hours after the start of fasting in the first and fourth weeks of Ramadan.

Contrast sensitivity (CS) was increased at the spatial frequency of three cycles per degree (cpd) at the end of the first week of Ramadan in comparison to the CS measured before Ramadan (𝑃 = 0.03). The mean CS values were increased at the spatial frequencies of 3 and 12 cpd at the end of the last week of Ramadan in comparison to the mean values measured before Ramadan (𝑃 = 0.01 for both).

Although we found statistically significant increases in CS at certain frequencies, we can conclude that Ramadan fasting has no negative effects on CS.

Since light scattering has a great impact on visual performances, this study was conducted to compare the effects of color filters and anti-reflective coating on contrast sensitivity (CS) in normal people under glare condition.

This semi-experimental study was conducted on 40 medical students (aged 19- 25 years). Ophthalmologic tests including visual acuity and refractive error measurement, biomicroscopy, fundoscopy, and CS assessment were conducted for all participants. CS was determined using Pelli-Robson chart at a distance of one meter. To measure the effect of glare on CS, we used an additional lighting source (60 W tungsten filament incandescent lamp) in the patient’s visual field. Thus, at an intensity of 2000 lux, the light source was placed at a distance of 18.5 cm from the patient’s eye in a way that it was 10 degrees above the subject’s visual axis. Monocular CS measurements were performed with and without glare. Monocular CS was evaluated again under glare conditions with the yellow and pink filters, with the transmission rate of 85%, and anti-reflective coating.

The mean log CS of subjects under glare (1.48±0.09) was lower than that in the absence of glare (1.71±0.09) (<0.001); moreover, repeated measures ANOVA showed the yellow filter (1.48±0.10), pink filter (1.47±0.10), and anti-reflective coating (1.47±0.09) had no significant impact on improving visual performance under glare condition (P=0.471).

Colored filters and anti-reflective coatings are not effective in enhancing the vision of young normal individuals under glare conditions and at low spatial frequencies.

To evaluate the effect of myopic photorefractive keratectomy (PRK) on color vision, contrast sensitivity and higher order aberrations (HOAs). Patients and

This prospective study was performed on 46 eyes of 23 patients with 3 to 6 diopter of myopia/myopic astigmatism undergoing PRK. Color vision using FransworthMunsell 100 hue test (©2011 X-Rite Inc., Michigan, U.S) and contrast sensitivity using CSV-1000 (Vector Vision, Dayton, OH) were tested preoperatively and 2 and 6 months postoperatively. HOAs were assessed using Zernike analysis map of Pentacam (OCULUS Optikgeräte GmbH, Germany) preoperatively and 6 months postoperatively.

No significant change was observed in color vision following PRK. Contrast sensitivity function was also preserved except for an increase in 12 cycles per degree (cpd) spatial frequency 6 months after surgery (P = 0.04). Total HOAs and primary spherical aberrations (total, anterior and posterior surface) increased significantly (P < 0.001), however, primary coma showed no statistically significant change 6 months after surgery compared to baseline values. Induced total HOAs significantly correlated with change in primary vertical coma and total, anterior, and posterior primary spherical aberration. No significant correlation was found between the changes in contrast sensitivity, color vision and HOAs with the amount of preoperative sphere and cylinder.

PRK with an aspheric profile in moderate myopia/ myopic astigmatism does not affect color vision and contrast sensitivity at 3, 6 and 18 cpd spatial frequencies. It increases total HOAs and spherical aberration, but not coma. It remains a good option for refractive correction of moderate.