Functional Acuity Contrast Test Research Articles

Impact of Keratoconus on Contrast Sensitivity

Objective: Keratoconus (KC) disrupts corneal shape, leading to irregular astigmatism and increased higher-order aberrations (HOA), ultimately affecting visual quality. While visual acuity (VA) remains the standard, its limitations in early KC diagnosis are recognized. This study aimed to evaluate the impact of KC on contrast sensitivity function (CSF), a potentially more sensitive measure of visual performance.Material and Methods: A case-control design compared CSF in KC patients (n=7) to healthy controls (n=16). All subjects achieved the best-corrected visual acuity (BCVA) of 6/9 or better (logMAR ≤0.10). Corneal topography was measured using Tomey TMS-5 to confirm KC diagnosis. CSF was assessed with the Functional Acuity Contrast Test (FACT).Results: KC eyes exhibited significantly reduced CSF across all spatial frequencies compared to controls (p-value<0.05). Row A of the FACT chart (representing the lowest spatial frequency, 1.5 cpd) demonstrated the most prominent difference (t (21)=-3.073, p-value=0.003).Conclusion: Our findings reveal that KC patients, despite achieving good BCVA, demonstrate measurable deficits in CSF. This suggests CSF measurement with FACT may be a valuable tool for the early diagnosis and monitoring of KC, potentially offering a more sensitive and comprehensive assessment of visual function compared to BCVA alone.

Visual and clinical outcomes after bilateral implantation of a novel extended depth of focus lens post cataract surgery.

To assess the visual and clinical outcomes after bilateral implantation of the novel extended depth of focus (EDOF) (AcrySof IQ Vivity) intraocular lens (IOL) using a micromonovision strategy. This was a prospective interventional study at a tertiary care center. Twenty patients (40 eyes) underwent bilateral implantation of AcrySof IQ Vivity IOL. Twelve weeks postoperatively, both uncorrected vision and corrected vision were assessed. Uniocular and binocular defocus curves with and without correction were noted subjectively as well as objectively on I-trace. Contrast sensitivity was assessed with a FACT (Functional Acuity Contrast Testing) machine, and objective parameters like modulation transfer function and Strehl ratio were also measured on I-Trace. Subjective quality of vision using a subjective questionnaire was also evaluated. The mean binocular postoperative uncorrected distance visual acuity in LogMAR was -0.03 ± 0.09, the uncorrected intermediate visual acuity was 0.03 ± 0.09, and the uncorrected near visual acuity was 0.28 ± 0.18. All defocus curves were smooth and broad with the uncorrected defocus curve (with the micromonovision strategy) better than the corrected defocus curve. The subjective depth of focus (DOF = 3.73) was more than objective DOF (1.93) (P < 0.05). Photopic contrast was better than mesopic at all frequencies. All aberrations increased at 5 mm pupil size compared to 3 mm pupil size and were statistically significant, except for the total eye spherical aberration, which shows no significant difference at 3 mm and 5 mm pupil size (P = 0.27). Spectacle independence for distance, intermediate, and near was achieved in 100%, 94.7%, and 94.7% cases in this study, respectively. Using the micromonovision strategy, the visual performance of this novel EDOF IOL was outstanding both subjectively and objectively.

Effect of Yellow Filter On Contrast Sensitivity Function In High Myopes

Background: This study examines the influence of yellow filter on the contrast sensitivity function in individuals with high myopia. Through a comprehensive analysis, we explore the potential enhancement of visual perception and contrast sensitivity in this population. The findings con-tribute to our understanding of effective interventions to optimize visual outcomes for high myopes. Purpose: A cross-sectional study was conducted where thirty-four (n=34) healthy young subjects (age range 17-25 years old) having high myopia (SER ≥ 6.00D) without any ocular pathology. Contrast sensitivity func-tion (CSF) was assessed using the Functional Acuity Contrast Test (FACT). First, the CSF was measured without the filter (baseline) then immediately after using a yellow filter (50% transmittance) and then after five minutes of adaptation of the yellow filter. The room illumination was constant at 150lux across all the subjects. Results: One-way repeated measure ANOVA showed that there was no statistically significant difference in contrast sensitivity function for spa-tial frequencies 1.5cpd, and 12cpd. However, there was a statistically significant difference in contrast sensitivity for spatial frequencies 3cpd; F(1.46, 48.20) =28.80, 6cpd; F (1.44, 47.43) =39.99 and 18cpd F (1.53, 50.47) = 44.26. Conclusion: There was an improvement at the moderate and high spatial frequencies (3cpd, 6cpd and 18cpd) but no changes were found at other spatial frequencies. This shows that yellow filter can help to improve the contrast sensitivity function in high myopes at moderate and high spatial frequencies.

Effect of decentration on the quality of vision: comparison between aspheric balance curve design and posterior aspheric design intraocular lenses.

To study the effect of decentration on the quality of vision in 2 aspheric intraocular lenses (IOLs): aspheric balance curve (ABC) design Vivinex iSert XY1 (Hoya Surgical Opticals, Inc.) and posterior aspheric design AcrySof IQ SN60WF (Alcon Laboratories, Inc.). Advanced Eye Centre, PGIMER, Chandigarh, India. Randomized prospective trial using a random number table. 85 eyes were randomized to group 1 (Vivinex XY1) and group 2 (AcrySof IQ) with 40 and 45 eyes, respectively. The higher-order aberration (HOA) profile, Strehl ratio, decentration of the IOL from the visual axis (decentration from the visual axis [DVA]) and the geometric axis (decentration from the geometric axis [DGA]), angle α, and κ were recorded on the iTrace aberrometer, and contrast sensitivity was measured using the Functional Acuity Contrast Test at 12 weeks postsurgery. A total of 85 eyes in 60 patients were evaluated in this study. The mean values of the Strehl ratio (P = .48) and the HOAs (P = .12) of both IOLs were comparable. The HOAs gradually increased with increasing DVA for both lenses at 3.0 mm, 4.0 mm, and 5.0 mm pupil sizes. On comparing the HOAs with the DGA, a statistically insignificant positive correlation was observed. The Strehl ratio did not deteriorate with an increasing angle α in the Vivinex XY1 group; however, it worsened in the AcrySof IQ group. Contrast sensitivity was comparable in both the IOLs except at 1.5 cycles per degree under photopic conditions where the AcrySof IQ was better. Decentration of the lens was best measured with respect to the visual axis. In eyes with a large α, the ABC design induced lesser HOAs and maintained a better Strehl ratio.

Contrast Sensitivity Measurement Tests and Methods

Contrast is a measure of the amount of lightness or darkness an object has in relationship to its background. Usually, it is described as Contrast Sensitivity (CS), which actually is the inverse of the contrast threshold. More often than not, stimulus set includes grating patterns of various sizes that are presented in a stationary manner or are dynamically presented by reversing the contrast at different rates.&#x0D; A variety of tests were developed, in order to asses and evaluate contrast sensitivity, in many different ways. A classical method, to check for contrast sensitivity, is the Pelli-Robson contrast sensitivity chart.&#x0D; The Bailey-Lovie contrast sensitivity chart is another letter chart that deals with differences in the number of letters read on the high and low contrast charts, with a main drawback, the necessity to follow the size of the letters.&#x0D; The Functional Acuity Contrast Test is designed to identify vision loss from a variety of disorders, many of which are not detected by high or low contrast Snellen Acuity tests. The MARS Letter Contrast Sensitivity Test shows good agreement with the Pelli-Robson test and possibly it may be the alternative to the Pelli-Robson chart, in clinical practice and research.

Prenatal exposure to glycol ethers and visual contrast sensitivity in 6-year-old children in the PELAGIE mother-child cohort.

Maternal occupational exposure to organic solvents during pregnancy has been associated with decreased visual function in offspring. Glycol ethers (GEs) belong to oxygenated solvents and are widely used both in occupational and domestic contexts. We aimed to assess associations between prenatal GEs exposure and contrast sensitivity in children. Six GE alkoxy carboxylic acidic metabolites (methoxyacetic acid [MAA], ethoxyacetic acid [EAA], ethoxyethoxyacetic acid [EEAA], butoxyacetic acid [BAA], phenoxyacetic acid [PhAA], and 2-methoxypropionic acid [2-MPA]) were measured in first morning void urine samples collected from 220 early-pregnancy women, in the mother-child PELAGIE cohort (France). Trained investigators administered the Functional Acuity Contrast Test (FACT) to the 6-year-old children, providing scores for 5 spatial frequencies (1.5-18 cycles per degree (cpd)). We standardized biomarker urinary concentrations on urine sampling conditions. Values below the LOD were imputed based on log-normal distribution, generating five datasets for multiple imputation. Linear regression models were adjusted for potential confounders. GE metabolites were detected in 70-98% of maternal urine samples. Phenoxyacetic acid (PhAA) had the highest median concentration (0.33mg/L), and 2-methoxypropionic acid (2-MPA) the lowest (0.01mg/L). Children with higher prenatal PhAA concentrations had poorer FACT scores at various spatial frequencies (fourth vs. first quartile: β18cpd=-0.90 (95% confidence interval CI=-1.64, -0.16), β12cpd=-0.92 (95%CI=-1.55, -0.29) and β1.5cpd=-0.69 (95%CI=-1.19, -0.20)). The 2-MPA log-scale concentration was negatively associated with the FACT score at the 3-cpd stimulus. PhAA is the metabolite of ethylene glycol monophenyl ether present in many cosmetics. 2-MPA is the metabolite of an isomer of propylene glycol methyl ether commonly present in household and industrial cleaning products. Although evidence of biological plausibility is lacking, the study suggests adverse impact of ubiquitous prenatal exposure to some GE on visual functioning among children.

Is contrast sensitivity a physiological marker in attention-deficit hyperactivity disorder?

Attention-deficit hyperactivity disorder (ADHD) is one of the most common childhood-onset psychiatric disorders. Although the etiology is complex and has not yet been clarified, dopamine is thought to play a role in the etiology. Methylphenidate (MPH) is a psychostimulant drug used as first-line treatment for ADHD and it inhibits dopamine and norepinephrine reuptake transporters. Dopamine also has an effect on retina and contrast sensitivity. Despite evidence indicating the effects of dopamine on contrast sensitivity, the results of studies examining contrast sensitivity in ADHD patients are inconsistent. Also, no studies have been encountered examining the possible effect of MPH on contrast sensitivity. The hypotheses of this study are that children with ADHD who have not used MPH will have lower contrast sensitivity levels than the members of the control group, that contrast sensitivity levels increase after the use of MPH, and that contrast sensitivity is a potential physiological marker for ADHD. The study was conducted with 30 children with ADHD and 30 children without ADHD. Psychiatric evaluations of the participants were conducted with the Schedule for Affective Disorders and Schizophrenia for School Age Children–Present and Lifetime—Turkish version, Conner’s Parent Rating Scale–Revised Short form and the Turgay DSM-IV-based Child and Adolescent Behavioral Disorders Screening and Rating Scale. Photopic contrast sensitivity was measured using the Functional Acuity Contrast Test (FACT). Results showed that FACT mean values of the control group were significantly higher than those of the ADHD group (pre-treatment) in all spatial frequencies. In four spatial frequencies (CPD 1.5, 3, 12 and 18), the FACT mean values of the control group were significantly higher than the ADHD group (during the OROS-MPH treatment). At all spatial frequencies, the mean values of the ADHD group during the OROS-MPH treatment were significantly higher than before the OROS-MPH treatment. In conclusion, the present study showed that contrast sensitivity is low in children with ADHD and increases significantly after OROS-MPH medication, but still did not reach the levels of the children without ADHD. Our findings suggest that contrast sensitivity may be a potential physiological marker in ADHD.

Influence of Intraocular Lens Asphericity and Blue Light Filtering on Visual Outcome, Contrast Sensitivity, and Aberrometry after Uneventful Cataract Extraction.

Purpose 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.MethodsOne 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.Results 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).ConclusionBioline 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.

Ocular findings in patients with attention deficit and hyperactivity.

To evaluate ocular findings, contrast sensitivity, color perception, and macular and retinal nerve fiber layer (RNFL) thickness in patients with attention-deficit/hyperactivity disorder (ADHD). This prospective study included a group of 37 patients aged 6-16years diagnosed with combined ADHD and a healthy control group of 37 children. The participants underwent an ophthalmological examination. Colorvisiontestingwas administeredusingtheIshiharaplates test. Contrast sensitivity test was performed using the Functional Acuity Contrast Test. Macular thickness and RNFL thickness were measured by spectral-domain optical coherence tomography. No significant difference was found between the patient and control groups with regard to ocular findings, color vision, and convergence insufficiency (p > 0.05). Contrast sensitivity level was significantly lower at four out of five spatial frequencies (1.5, 3, 12, and 18cpd) in the patient group compared to the control group. The RNFL thickness in nasal quadrant and macular thickness was significantly higher in the healthy control group compared to the ADHD group. Contrast sensitivity levels and the nasal quadrant RNFL thickness were significantly lower in the patient group compared to the control group. Based on the findings of the study, we suggest that the level of contrast in the tools used by ADHD patients in daily life settings should be enhanced.

Effect of Vitamin D Deficiency on Contrast Sensitivity Function

ABSTRACT Purpose The purpose of this study is to investigate the effects of vitamin D (vit D) deficiency on contrast sensitivity (CS) function and retinal layers. Materials and methods Group 1 consisted of 42 patients aged between 18 and 50 years with vit D deficiency and Group 2 consisted of sex- and age-matched 34 healthy subjects with normal vit D levels. Functional acuity contrast testing (FACT) was performed using the Optec 6500 vision testing system. The average retinal nerve fiber layer (RNFL) thickness and macular thickness (MT) obtained from nine macular areas in the Early Treatment Diabetic Retinopathy Study were evaluated using SD-OCT (RS-3000; Nidek Inc., Fremont, CA, USA) following a detailed ophthalmologic examination. Measurements were performed on both eyes. Results A lower CS was found in Group 1 compared to Group 2 in all spatial frequencies. A statistically significant difference was observed between the groups in 6, 12 and 18 cpd spatial frequencies, respectively. (p = .004, p = .001, p = .042, respectively). There was no statistically significant difference between groups in terms of RNFL thicknesses (p = .200). There was an increase in MT in Group 1. However, this increase was statistically significant in the inferior inner area in the right eye, and in the inferior inner, temporal inner and outer macular areas in the left eye (p = .018, p = .003, p = .033, p = .040, respectively). Conclusion It was observed that vit D deficiency had negative effects on CS function and also caused thickness difference in certain segments of retinal layers.

Improvement or Worsening of Human Contrast Sensitivity Due to Blue Light Attenuation at 450 nm.

PurposeThe work was aimed at comparing contrast sensitivity performance in an indoor environment with two filters, which differ only in the presence of a band at 450±20 nm in the transmittance spectrum.Patients and MethodsThirty-nine subjects participated. The filters were the Standard (ST) and Professional (PRO) Drive lenses (Hoya, Japan), the latter showing the attenuation band at 450 nm. Photopic contrast sensitivity (CS) was measured at different spatial frequencies from 1.5 to 18 cpd through Functional Acuity Contrast Test with both lenses (LogCSST and LogCSPRO, respectively). The areas under the curves of LogCSST and LogCSPRO as a function of the spatial frequency were also considered.ResultsIn the range of the measured values of LogCSST for the thirty-nine participants, at each spatial frequency and also for the areas, the difference Δ = LogCSPRO – LogCSST was found to decrease and change sign from positive to negative as a function of LogCSST, thus allowing to deduce a threshold (LogCSthreshold) for LogCSST corresponding to Δ=0. Significant CS worsening was found with the PRO compared to the ST lens for the subjects showing LogCSST > LogCSthreshold. Vice versa, CS improvement was found when LogCSST < LogCSthreshold.ConclusionIn the choice of a blue-filtering lens, practitioners should take into consideration that the attenuation of light in the range 420–470 nm is expected to produce a CS worsening in subjects showing a relatively high initial CS (higher than a threshold CS). For these subjects, the general reduction of transmitted light intensity prevails on possible advantages. On the contrary, subjects showing a relatively low initial CS are expected to show a CS improvement because the attenuation of light in the range 420–470 nm is expected to reduce intraocular scattering and to mimic the effect as an optical filter of the human macular pigment, advantages which prevail on the reduction of the transmitted light intensity.

Contrast sensitivity before and after small incision lenticule extraction and femtosecond laser in situ keratomileusis

Introduction: Contrast sensitivity function after laser ablation of the cornea in refractive surgery is an important tool for measuring quality of visual function. The effect of small incision lenticule extraction (SMILE) and femtosecond laser in situ keratomileusis (FS-LASIK) on visual function can be compared by measuring spatial contrast sensitivity.&#x0D; Purpose: This study was to compare contrast sensitivity function in patients undergoing refractive surgery for myopia at Tilganga Institute of Ophthalmology.&#x0D; Methods: In a retrospective study, 15 subjects who underwent refractive surgeries comprising 9 cases of SMILE and 6 cases of FS-LASIK at Tilganga Eye Hospital were enrolled in the study. A major assessment included best corrected monocular contrast sensitivity with functional vision analyzer at spatial frequencies of 1.5, 3, 6, 12, and 18 cycles/deg in photopic condition (85 cd/m2) before, 3 months, and 1 year after the surgery. The average functional acuity contrast test scores for each spatial frequency were recorded. Differences between preoperative and postoperative contrast sensitivity at each spatial frequency were analyzed through parametric paired Student’s t-test.&#x0D; Results: Contrast sensitivity of postoperative FS-LASIK and SMILE did not differ from preoperative values at a photopic level. However, at high spatial frequency (12 and 18 cycles/deg), contrast sensitivity function improved significantly (p &lt; 0.05) in eyes after FS-LASIK. Eyes after SMILE surgery did not show any reduction in contrast sensitivity at all the spatial frequencies.&#x0D; Conclusion: Under photopic conditions, the contrast sensitivity function is unaffected by SMILE or FS-LASIK.

Effect of Fasting on Contrast Sensitivity in Healthy Males.

PurposeTo evaluate the effect of fasting on contrast sensitivity (CS) in healthy male individuals during the month of Ramadan.MethodsThis 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.ResultsContrast 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 ( = 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 ( = 0.01 for both).ConclusionAlthough we found statistically significant increases in CS at certain frequencies, we can conclude that Ramadan fasting has no negative effects on CS.

Vision-related quality of life after pars plana vitrectomy with or without combined cataract surgery for idiopathic macular hole patients.

To evaluate the influence of vision-related quality of life (VR-QOL) after pars plana vitrectomy (PPV) with or without combined cataract surgery for idiopathic macular hole (IMH) patients. This prospective consecutive case series study included 53 eyes of 53 consecutive IMH patients who were divided into two groups: 34 eyes underwent PPV combined with cataract surgery (combined group), 19 eyes only underwent PPV (vitrectomy group). Clinical data were collected at baseline and 3 and 6months after surgery, respectively, including VR-QOL evaluated by The National Eye Institute 25-Item Visual Function Questionnaire (VFQ-25), logarithm of minimal angle of resolution best-corrected visual acuity (logMAR BCVA) using ETDRS chart, severity of metamorphopsia evaluated by M-Charts, contrast sensitivity evaluated by functional acuity contrast test, MH diameter detected by SD-OCT and lens opacity assessment evaluated by Lens Opacity Classification System III (LOCS III). ANOVA and LSD, Wilcoxon signed-rank test were used to compare the difference in logMAR BCVA, metamorphopsia scores, contrast sensitivity, LOCS III scores and VFQ-25 scores between three time points; Spearman's rank correlation test was used to test the correlations between logMAR BCVA, metamorphopsia scores, contrast sensitivity, LOCS III scores and VFQ-25 scores. All eyes had achieved an anatomical success after surgery in both groups. BCVA (logMAR), metamorphopsia and contrast sensitivity were significantly improved at month 3 and month 6 (p = < 0.005). VFQ-25 composite and four subscale scores (general vision, near activities, distant activities, role difficulties) were significantly improved in combined group at month 6 compared with baseline (p = 0.011, 0.001, 0.003, < 0.001, 0.009). VFQ-25 composite and two subscale scores (general vision, role difficulties) were significantly and negatively correlated with logMAR BCVA (p = 0.046, 0.011, 0.012) and metamorphopsia (p = 0.009, 0.002, < 0.001) in combined group. VFQ-25 composite and four subscale scores (general vision, near activities, distance activities, mental health) were significantly improved in vitrectomy group at month 3 compared with baseline (p = 0.014, 0.047, 0.011, 0.018, 0.037). VFQ-25 composite score and mental health score were significantly decreased in vitrectomy group at month 6 compared with month 3 (p = 0.031, 0.029) and were significantly and negatively correlated with LOCS III score (p = 0.047, 0.017) at month 6. Visual function and VR-QOL were significantly improved after successful macular hole surgery. The fluctuation of VR-QOL after surgery was attributed to the progression of the lens opacity. PPV combined with cataract surgery can help macular hole patients to maintain stable VR-QOL improvement by degrees.

Impact of hypoxic and mesopic environments on visual acuity, contrast sensitivity and accommodation in subjects with LASIK surgery and aircrew candidate

BackgroundThe safety of Laser-assisted in situ keratomileusis (LASIK) in aircrew was unclear, in addition, LASIK was not yet approved for aircrew of Taiwan Air Force. This study was aimed to evaluate visual performance in LASIK eyes in hypoxic and twilight environment. Methods48 myopic eyes of 24 subjects enrolled in this study were divided into LASIK group and control group. Subjects were exposed in hypoxic (15% O2) and mesopic (3 cd/m2) environment. Visual performance was evaluated using the Early Treatment of Diabetic Retinopathy Study (ETDRS) visual chart, and Functional Acuity Contrast Test (FACT) before and after the expirement. Physiological parameters of all subjects were measured and recorded throughout the experiment. ResultsThere was no significant difference of the two groups regarding their age, height, weight, and BMI. There is significant difference of preoperative spherical refractive error between the two groups. The results of physiological parameters were similar between two groups. Under normoxic conditions, there were no significant difference regarding distant vision in photopic and mesopic environments, so as for near vision. As a whole, the contrast sensitivity of the LASIK group were lowered than that of the control group about 35%, under whether normoxic or hypoxic conditions; photopic or mesopic circumstances. Under normoxic conditions, the measured accommodation of the LASIK group were 21% lowered than that of the control group and 31% lowered under hypoxic circumstances. ConclusionThere was no significant difference of visual acuity between the two groups regarding hypoxic and mesopic environment, but reduced contrast sensitivity was significant in LASIK group as compared to those of the control group. Accommodation was significantly lowered in LASIK group, compared with control group, in hypoxic environment. Whether postoperative visual performance after LASIK in aircrew during flying duty is safe might need further investigation.

Children’s contrast sensitivity function in relation to organophosphate insecticide prenatal exposure in the mother-child PELAGIE cohort

Human exposure to organophosphate pesticides (OP) is widespread. Several studies suggest that OP prenatal exposure alters the development of cognitive and behavioural functions in children, but the effects of OP prenatal exposure on child sensory functions are largely unknown. The aim of the study was to evaluate the association between OP prenatal exposure and visual processing in school-aged children from the mother-child PELAGIE cohort (France). OP biomarkers of exposure were measured in maternal urine samples at the beginning of pregnancy. The Functional Acuity Contrast Test (FACT) was used to assess visual contrast sensitivity in 180 children at 6 years of age. Linear regression models were performed on all children, and separately for boys and girls, taking into account various potential confounders, including maternal education and breastfeeding. No associations were observed in the whole sample, while maternal OP urinary metabolite levels were associated with a decrease of FACT scores in boys. These findings indicate that OP prenatal exposure might impair visual processing later in life in boys only.

Time to Refocus Assessment of Vision in Older Adults? Contrast Sensitivity but Not Visual Acuity Is Associated With Gait in Older Adults.

The relationship between measures of visual function and gait related risk factors for falls is unclear. In this study, we examine the relationship between visual function (visual acuity [VA] and contrast sensitivity [CS] at multiple spatial frequencies) and quantitative spatiotemporal gait, using a large, nationally representative sample of community dwelling older adults. Participants aged 50 and over were recruited as part of The Irish Longitudinal Study on Ageing (TILDA). VA was measured with the LogMAR chart according to the Early Treatment of Diabetic Retinopathy Study protocol. CS was measured at five spatial frequencies ranging 1.5 to 18 cycles per degree (cpd) using the Functional Acuity Contrast Test. Gait speed, cadence, and stride length were measured using the GAITRite system. Multivariate analysis examined associations between gait and visual performance parameters adjusting for socioeconomic, physical, cognitive, and mental health covariates. Data from 4,678 participants were analyzed (age 61.7 ± 8.3 years, 54.1% woman). Poorer CS at 1.5 cpd and 3.0 cpd (low spatial frequency) was independently associated with decreased stride length (CS at 1.5 cpd: β = .031; p = .001 and CS at 3.0 cpd: β = .020; p = .001) but not cadence or gait speed. There was no evidence of an association between VA and any of the gait variables considered (p > .05). Reduced CS, at low spatial frequencies, is independently associated with shorter stride length, while VA is not associated with any gait measures. This evidence suggests that it may be necessary to consider refocus of the assessment of vision to include the most appropriate measures.

Does Retinal Neurodegeneration Seen in Diabetic Patients Begin in the Insulin Resistance Stage?

Objectives: To investigate whether retinal neurodegeneration and impairment in contrast sensitivity (CS), which have been demonstrated to begin in diabetic patients before the presence of signs of diabetic retinal vasculopathy, also occur in the stage of insulin resistance.Materials and Methods: The average, minimum and sectoral (inferior, superior, inferonasal, superonasal, inferotemporal and superotemporal) thicknesses of the ganglion cell-inner plexiform layer (GCIPL) measured using optical coherence tomography were compared between an insulin-resistant group and control group in order to evaluate the presence of retinal neurodegeneration. The CS of the two groups was also compared according to the logarithmic values measured at spatial frequencies of 1.5, 3, 6, 12 and 18 cycles per degree in photopic light using functional acuity contrast test (FACT).Results:Twenty-five eyes of 25 patients with insulin resistance (insulin resistant group) and 25 eyes of 25 healthy subjects (control group) were included in this study. There were no statistically significant differences between the two groups in any of the spatial frequencies in the FACT. The mean average GCIPL thickness and mean GCIPL thickness in the inferotemporal sector were significantly less in the insulin-resistant group when compared with the control group (mean average GCIPL thicknesses in the insulin-resistant and control groups were 83.6±4.7 µm and 86.7±3.7 µm respectively, p=0.01; mean inferotemporal GCIPL thicknesses in the insulin-resistant and control groups were 83±6.0 µm and 86.7±4.6 µm respectively, p=0.02).Conclusion: Although it may not lead to functional visual impairment such as CS loss, the retinal neurodegeneration seen in diabetic patients may begin in the insulin resistance stage.

Visual acuity and contrast sensitivity screening with a new iPad application

We present a new iPad application (app) for a fast assessment of Visual Acuity (VA) and Contrast Sensitivity (CS) whose reliability and agreement was evaluated versus a commercial screening device (Optec 6500). The measurement of VA was programmed in the app in accordance with the Amblyopia Treatment Study protocol. The CS was measured with sinusoidal gratings of four different spatial frequencies: 3, 6, 12 and 18cpd at the same contrast values of the Functional Acuity Contrast Test (FACT) included in the Optec 6500. Forty-five healthy subjects with monocular corrected visual acuities better than 0.2 logMAR participated in the agreement study. Bland-Altman analyses were performed to assess the agreement and Deming regressions to calculate Mean Differences (MDs) and Limits of Agreement (LoAs). Coefficients of reliability were 0.15 logMAR for our method and 0.17 logMAR for the ETDRS testing protocol. For testing the CS, our test showed no statistically significant differences compared with the FACT at any spatial frequency (p>0.05). The MDs were lower than 0.05 log units for all spatial frequencies.

Visual dysfunction, but not retinal thinning, following anti-NMDA receptor encephalitis.

Objective:To assess structural and functional changes in the afferent visual system following anti-NMDA receptor (NMDAR) encephalitis.Methods:In this cross-sectional study including 31 patients after acute NMDAR encephalitis and matched healthy controls, visual function was assessed as high-contrast visual acuity using Early Treatment Diabetic Retinopathy Study charts and low-contrast sensitivity using Functional Acuity Contrast Test. Retinal changes were measured using optical coherence tomography with assessment of peripapillary retinal nerve fiber layer (pRNFL) and macular intraretinal layer thicknesses. Residual clinical impairment was described using the modified Rankin Scale.Results:High-contrast (logMAR 0.02 ± 0.14 vs −0.09 ± 0.14, p < 0.001) and low-contrast (area under the curve 1.89 ± 0.21 vs 2.00 ± 0.26, p = 0.039) visual acuity were reduced in patients in comparison to healthy controls. More severely affected patients performed worse in visual acuity testing than patients with good recovery (logMAR −0.02 ± 0.11 vs 0.08 ± 0.17, p = 0.030). In contrast, patients did not differ from matched healthy controls in pRNFL or in thickness of intraretinal layers, including the ganglion cell complex, the inner nuclear layer, the outer nuclear and plexiform layers, and the photoreceptor layer.Conclusions:After acute NMDAR encephalitis, patients have mild visual dysfunction in comparison to matched healthy controls, while retinal structure appears unaltered. These observations could point to an impairment of anterior or posterior visual pathway NMDAR function that is similar to dysfunction of NMDAR in cerebral cortex and subcortical structures. Alternatively, residual cognitive impairment might reduce visual function.