Predictors of macular pigment and contrast threshold in Spanish healthy normolipemic subjects (45-65 years) with habitual food intake

Introduction

The dietary carotenoids lutein (L) and zeaxanthin (Z) are transported in the bloodstream by lipoproteins, sequestered by adipose tissue, and eventually captured in the retina where they constitute macular pigment. There are no L&Z dietary intake recommendations nor desired blood/tissue concentrations for the Spanish general population. Our aim was to assess the correlation of L&Z habitual dietary intake (excluding food supplements), resulting serum concentrations and lipid profile with macular pigment optical density (MPOD) as well as the contrast sensitivity (CT), as visual outcome in normolipemic subjects (n = 101) aged 45–65.

Methods

MPOD was measured by heterochromatic flicker photometry, serum L&Z by HPLC, the dietary intake by a 3-day food records and CT using the CGT-1000-Contrast-Glaretester at six stimulus sizes, with and without glare.

Results

Lutein and zeaxanthin concentrations (median) in serum: 0.361 and 0.078 μmol/L, in dietary intake: 1.1 mg L+Z/day. MPOD: 0.34du. L+Z intake correlates with their serum concentrations (rho = 0.333, p = 0.001), which in turn correlates with MPOD (rho = 0.229, p = 0.000) and with fruit and vegetable consumption (rho = 0.202, p = 0.001), but not with lutein+zeaxanthin dietary intake. MPOD correlated with CT, with and without glare (rho ranges: -0.135, 0.160 and -0.121, –0.205, respectively). MPOD predictors: serum L+Z, L+Z/HDL-cholesterol (β-coeficient: -0.91±0.2, _95%CI: -1.3,-0.5) and HDL-cholesterol (R² = 15.9%). CT predictors: MPOD, mainly at medium and smaller visual angles (corresponding to spatial frequencies for which sensitivity declines with age) and gender (β-coefficients ranges: -0.95,-0.39 and -0.13,-0.39, respectively).

Conclusion

A higher MPOD is associated with a lower ratio of L+Z/HDL-cholesterol and with a lower CT (higher contrast sensitivity). The HDL-cholesterol would also act indirectly on the CT improving the visual function.

The Functional Vision Protection Effect of Danshensu via Dopamine D1 Receptors: In Vivo Study

Danshensu, a traditional herb-based active component (Salvia miltiorrhiza Bunge), has garnered attention, due to its safety, nutritional value, and antioxidant effects, along with cardiovascular-protective and neuroprotective abilities; however, its effect on the retinal tissues and functional vision has not been fully studied. The objective of this study was to analyze the protective effect of danshensu on retinal tissues and functional vision in vivo in a mouse model of light-induced retinal degeneration. High energy light-evoked visual damage was confirmed by the loss in structural tissue integrity in the retina accompanied by a decline in visual acuity and visual contrast sensitivity function (VCSF), whereas the retina tissue exhibited severe Müller cell gliosis. Although danshensu treatment did not particularly reduce light-evoked damage to the photoreceptors, it significantly prevented Müller cell gliosis. Danshensu exerted protective effects against light-evoked deterioration on low spatial frequency-based VCSF as determined by the behavioral optomotor reflex method. Additionally, the protective effect of danshensu on VCSF can be reversed and blocked by the injection of a dopamine D1 receptor antagonist (SCH 23390). This study demonstrated that the major functional vision promotional effect of danshensu in vivo was through the dopamine D1 receptors enhancement pathway, rather than the structural protection of the retinas.

Effects of Citicoline, Homotaurine, and Vitamin E on Contrast Sensitivity and Visual-Related Quality of Life in Patients with Primary Open-Angle Glaucoma: A Preliminary Study

The aim of the present study was to evaluate the effects of supplementation with a fixed combination of citicoline 500 mg, homotaurine 50 mg, and vitamin E 12 mg (CIT/HOMO/VITE) on contrast sensitivity and visual-related quality of life in patients with primary open-angle glaucoma (POAG) in mild stage. This was a multicenter, observational, cross-over, short-term, pilot study on POAG patients with stable controlled intraocular pressure (IOP). Patients were randomly assigned to Group 1 (current topical therapy for 4 months and then current topical therapy plus CIT/HOMO/VITE for 4 months) or Group 2 (CIT/HOMO/VITE in addition to current topical therapy for 4 months and then topical therapy alone for 4 months). Best-corrected visual acuity, IOP, visual field, and the Spaeth/Richman contrast sensitivity (SPARCS) test score were recorded at baseline and after 4 and 8 months. The Glaucoma Quality of Life-15 (GQL-15) questionnaire was administered at each check time. Forty-four patients were assigned to Group 1 and 65 to Group 2. Over the follow-up period, there were no significant changes in IOP or visual field findings, whereas SPARCS and GQL-15 findings significantly varied from baseline, both being improved in subjects treated with CIT/HOMO/VITE fixed combination. These results demonstrate that a daily intake of a fixed combination of citicoline, homotaurine, and vitamin E in addition to the topical medical treatment significantly increased the total score of the contrast sensitivity test and the quality of life in patients with POAG.

Serotonin improves behavioral contrast sensitivity of freely moving rats

Serotonin (5-HT) is a neuromodulator secreted from serotonergic neurons located in the pons and upper brain stem in a behavioral context-dependent manner. The serotonergic axon terminals innervate almost the whole brain, causing modulatory actions on various brain functions including vision. Our previous study demonstrated the visual responses of neurons in the primary visual cortex (V1) of anesthetized monkeys were modulated by the activation of 5-HT receptors depending on the response magnitude, in which 5-HT2A receptor-selective agonists enhanced weak visual responses but not strong responses. This observation suggests that the activation of serotonergic receptors modulates neuronal visual information processing to improve the behavioral detectability of a stimulus. However, it remains unknown if 5-HT improves visual detectability at the behavioral level. To investigate this point, visual detectability was measured as contrast sensitivity (CS) in freely moving rats using a two-alternative forced-choice visual detection task (2AFC-VDT) combined with the staircase method. The grating contrast was decreased or increased step by step after a correct choice (hit) or incorrect choice (miss), respectively. CS was evaluated as an inverse value of the visual contrast threshold. The effect of the intraperitoneal administration of fluoxetine (FLX, 5 mg/kg), a selective serotonin reuptake inhibitor, on CS was tested. The CS of rats was significantly higher in FLX than control conditions, and the drug effect showed specificity for the spatial frequency (SF) of a grating stimulus, in which CS improvement was observed at optimal SF but not non-optimal high SF. Thus, we conclude that endogenously-secreted serotonin in the brain improves visual detectability, which may be mediated by vision-related neurons acquiring SF information of the visual stimulus.

Association of Cadmium and Lead Exposure With the Incidence of Contrast Sensitivity Impairment Among Middle-aged Adults

Importance

Contrast sensitivity (CS) is an important indicator of visual function that affects daily life, including mobility, visually intensive tasks, safety, and autonomy. Understanding the risk factors for CS impairment could prevent decreases in visual function.

Objective

To determine the incidence of and factors associated with CS impairment in a large cohort.

Design, Setting, and Participants

The Beaver Dam Offspring Study is an ongoing longitudinal cohort study of aging involving adults in Beaver Dam, Wisconsin. Participants who were free of CS impairment in both eyes at baseline were included (N = 1983). Baseline data collection occurred from June 8, 2005, through August 4, 2008, when the participants ranged from 21 to 84 years of age. Two follow-up examinations occurred at 5-year intervals: one was conducted between July 12, 2010, and March 21, 2013, and the other between July 1, 2015, and November 13, 2017. Data analysis was performed from November 27, 2017, to February 27, 2018.

Main Outcomes and Measures

Contrast sensitivity testing was conducted with Pelli-Robson letter sensitivity charts, and incident impairment was defined as a log CS score less than 1.55 in either eye at any follow-up examination. Cadmium and lead levels were measured in whole blood with inductively coupled plasma mass spectrometry. Associations between baseline characteristics and CS impairment incidence were examined using Cox proportional hazard models and quantified as hazard ratios (HRs) with 95% CI.

Results

Of the 1983 participants included, 1028 (51.8%) were female and 955 (48.2%) were male, with a mean (SD) age of 48 (9.3) years. The 10-year cumulative incidence of CS impairment was 24.8% (95% CI, 22.9-26.8), similar in women (24.9%) and men (24.6%), and highest in the oldest age group (65-84 years) at 66.3%. In multivariable models, cadmium level in the highest quintile (HR, 1.35; 95% CI, 1.02-1.78), older age (HR, 1.36; 95% CI, 1.25-1.47), larger waist circumference (HR, 1.06; 95% CI, 1.01-1.11), and more plaque sites (1-3 sites: HR, 1.43; 95% CI, 1.07-1.92; 4-6 sites: HR, 2.75; 95% CI, 1.26-6.05) were among the factors associated with increased risk, while male sex (HR, 0.77; 95% CI, 0.60-0.98) and any alcohol consumption (HR, 0.61; 95% CI, 0.43-0.88) were associated with decreased risk. Results were similar when smoking status replaced cadmium exposure in the models. Lead level was not associated with increased risk.

Conclusions and Relevance

This study's findings suggest that incident CS impairment was common in the 10-year follow-up, with cadmium, but not lead, exposure associated with increased risk. The associations of diminished CS with other modifiable risk factors found appear to imply that changes in behavior may reduce future incidence of CS impairment.

The neuro-ophthalmological effects related to long-term occupational exposure to organic solvents in painters

PURPOSE

Organic solvents are widely used in many industries, and usually, exposure occurs with mixtures of solvents. Organic solvent mixtures are known for their ability to affect tissues of high lipid content including the myelin sheath in the nervous system. The purpose of this work was to study the evidence that long-term (more than 10 years) exposure to organic solvent mixtures among painters can induce neuro-ophthalmological effects on the function of retinal ganglion cells and the optic tract.

METHODS

Twenty workers with long-term occupational exposure to mixed organic solvents were compared to 40 control subjects. The controls were matched for age, gender, and demographic characteristics but were not occupationally exposed to any known organic solvents, using the following comparators: visual evoked potential (VEP), electroretinogram (ERG), color vision (CV), and contrast sensitivity (CS) testing. Environmental monitoring was done in the work environment with consideration to the American Conference of Governmental Industrial Hygienists Threshold Limit Values (ACGIH-TLVs).

RESULTS

The exposed group had significantly longer latency and higher amplitude of VEP waves especially P100, higher Color Confusion Index (CCI), especially affecting the blue-yellow spectrum, and lower Log CS. There was no significant difference between exposed and nonexposed groups in full-field flash ERG response; however, in the pattern ERG, the exposed group had significantly longer latency of P50, which reflects changes in the retinal ganglion cell.

CONCLUSION

Long-term occupational exposure to mixed organic solvents appeared to affect the optic tract functions in the form of increasing latency of VEP response, affecting the quality of CV and decreasing CS. It also affects the retinal ganglion cell layer with increased latency of P50 of the pattern ERG response.

Organic solvent exposure and contrast sensitivity: comparing men and women

The goal of this study was to compare the visual contrast sensitivity (CS) of men and women exposed and not exposed to organic solvents. Forty-six volunteers of both genders aged between 18 and 41 years (mean±SD=27.72±6.28) participated. Gas station attendants were exposed to gas containing 46.30 ppm of solvents at a temperature of 304±274.39 K, humidity of 62.25±7.59% and ventilation of 0.69±0.46 m/s (a passive gas chromatography-based sampling method was used considering the microclimate variables). Visual CS was measured via the psychophysical method of two-alternative forced choice using vertical sinusoidal gratings with spatial frequencies of 0.2, 0.5, 1.0, 2.0, 5.0, 10.0, and 16.0 cpd (cycles per degree) and an average luminance of 34.4 cd/m2. The results showed that visual CS was significantly lower (P<0.05) in the following groups: i) exposed men compared to unexposed men at frequencies of 0.2, 0.5, 1.0, and 2.0 cpd; ii) exposed women compared to unexposed women at a frequency of 5.0 cpd; and iii) exposed women compared to exposed men at a frequency of 0.5 cpd, even at exposures below the tolerance limit (300 ppm). These results suggest that the visual CS of exposed men was impaired over a wider range of spatial frequencies than that of exposed women. This difference may have been due to the higher body fat content of women compared to that of men, suggesting that body fat in women can serve as a protective factor against neurotoxic effects.

Opposing effects of atropine and timolol on the color and luminance emmetropization mechanisms in chicks

This study analyzed the luminance and color emmetropization response in chicks treated with the nonselective parasympathetic antagonist atropine and the sympathetic β-receptor blocker timolol. Chicks were binocularly exposed (8h/day) for 4days to one of three illumination conditions: 2Hz sinusoidal luminance flicker, 2Hz sinusoidal blue/yellow color flicker, or steady light (mean 680lux). Atropine experiments involved monocular daily injections of either 20μl of atropine (18nmol) or 20μl of phosphate-buffered saline. Timolol experiments involved monocular daily applications of 2 drops of 0.5% timolol or 2 drops of distilled H2O. Changes in the experimental eye were compared with those in the fellow eye after correction for the effects of saline/water treatments. Atropine caused a reduction in axial length with both luminance flicker (-0.078±0.021mm) and color flicker (-0.054±0.017mm), and a reduction in vitreous chamber depth with luminance flicker (-0.095±0.023mm), evoking a hyperopic shift in refraction (3.40±1.77D). Timolol produced an increase in axial length with luminance flicker (0.045±0.030mm) and a myopic shift in refraction (-4.07±0.92D), while color flicker caused a significant decrease in axial length (-0.046±0.017mm) that was associated with choroidal thinning (-0.046±0.015mm). The opposing effects on growth and refraction seen with atropine and timolol suggest a balancing mechanism between the parasympathetic and β-receptor mediated sympathetic system through stimulation of the retina with luminance and color contrast.

[Early effects of PCE exposure on visual function among dry cleaning workers]

BACKGROUND

A number of studies have shown a possible correlation between exposure to perchlorethylene (PCE) in dry cleaning workers and impairment of colour perception.

OBJECTIVES

to ascertain the possible presence of alterations in visual function in a group of workers exposed to current limit value levels of PCE.

METHODS

The study was conducted on 38 workers exposed to PCE in 21 dry cleaning establishments in the district of Modena and 60 controls selected according to criteria of comparability. We measured exposure to PCE among the dry cleaning workers using environmental monitoring (mean exposure 16.9 mg/m3). Both groups then answered a medical history questionnaire and underwent the Ishihara test for evaluating exclusion criteria followed by Lanthony D15d and Visual Acuity in Contrast Reduced (VCS) tests to evaluate changes in visual function. The results of Lanthony's test were expressed using Index Confusion Chromatic (ICC).

RESULTS

In the cases the average value of ICC was 1.28 (DS 0.21) and in the controls 1.15 (SD 0.21); the difference was statistically significant (p &lt;0.01). The values of ICC tended to be worse in subjects engaged only in the washing phase, who also had higher levels of exposure to PCE (mean exposure 26.8 mg/m3). The values of VCS for each frequency did not show, however, significant differences between the two groups.

CONCLUSIONS

On this basis, our data indicate that occupational exposure to PCE well below the current limit values may still be able to induce impairment of colour perception and that such levels are therefore not adequately protective, at least against these effects.

Styrene-associated health outcomes at a windblade manufacturing plant

BACKGROUND

Health risks of using styrene to manufacture windblades for the green energy sector are unknown.

METHODS

Using data collected from 355 (73%) current windblade workers and regression analysis, we investigated associations between health outcomes and styrene exposure estimates derived from urinary styrene metabolites.

RESULTS

The median current styrene exposure was 53.6 mg/g creatinine (interquartile range: 19.5-94.4). Color blindness in men and women (standardized morbidity ratios 2.3 and 16.6, respectively) was not associated with exposure estimates, but was the type previously reported with styrene. Visual contrast sensitivity decreased and chest tightness increased (odds ratio 2.9) with increasing current exposure. Decreases in spirometric parameters and FeNO, and increases in the odds of wheeze and asthma-like symptoms (odds ratios 1.3 and 1.2, respectively) occurred with increasing cumulative exposure.

CONCLUSIONS

Despite styrene exposures below the recommended 400 mg/g creatinine, visual and respiratory effects indicate the need for additional preventative measures in this industry.

Corticosteroids for treating optic neuritis

BACKGROUND

Optic neuritis is an inflammatory disease of the optic nerve. It usually presents with an abrupt loss of vision and recovery of vision is almost never complete. It occurs more commonly in women than in men. Closely linked in pathogenesis, optic neuritis may be the initial manifestation for multiple sclerosis. In some people, no underlying cause can be found.

OBJECTIVES

The objective of this review was to assess the effects of corticosteroids on visual recovery in eyes with acute optic neuritis.

SEARCH METHODS

We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (The Cochrane Library 2015, Issue 4), MEDLINE (January 1950 to April 2015), EMBASE (January 1980 to April 2015), Latin American and Caribbean Health Sciences Literature (LILACS) (January 1982 to April 2015), PubMed (January 1946 to April 2015), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrials.gov), and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). There were no date or language restrictions in the electronic searches for trials. The metaRegister of Controlled Trials (mRCT) was last searched on 6 March 2014. The electronic databases were last searched on 7 April 2015. We also searched reference lists of identified trial reports for additional trials.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) that evaluated systemic corticosteroids, in any form, dose or route of administration, in people with acute optic neuritis.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane.

MAIN RESULTS

We included six RCTs with a total of 750 participants. Each trial was conducted in a different country: Denmark, Germany, India, Japan, UK, and United States. Additionally, we identified two ongoing trials not due to be completed until 2016. Among the six trials included in this review, we judged one to be at high risk of bias. The remaining five trials were judged to be at either low or uncertain risk of biases.Five trials compared only two intervention groups and one trial had a three-arm comparison of oral corticosteroids or intravenous corticosteroids with placebo. Of the five trials with only two intervention groups, two trials compared oral corticosteroids versus placebo, two trials compared intravenous corticosteroids with placebo, and one trial compared intravenous dexamethasone with intravenous methylprednisolone plus oral prednisolone.Three trials evaluating oral corticosteroids used varying doses of corticosteroids versus placebo. In the meta-analyses to assess visual acuity, the risk ratio (RR) was 1.00 (95% confidence interval (CI) 0.82 to 1.23; participants = 398) at one month; 0.92 (95% CI 0.77 to 1.11; participants = 355) at six months; and 0.93 (95% CI 0.70 to 1.24; participants = 368) at one year. In the meta-analyses of two trials evaluating corticosteroids with total dose greater than 3000 mg administered intravenously, the RR of normal visual acuity (defined as 20/20 Snellen fraction or equivalent) in the intravenous corticosteroids group compared with the placebo group was 1.05 (95% CI 0.88 to 1.26; participants = 346) at six months. The RR of contrast sensitivity in the normal range for the same comparison was 1.11 (95% CI 0.92 to 1.33; participants = 346) at six months follow-up. The RR of normal visual field for this comparison was 1.08 (95% CI 0.96 to 1.21; 346 participants) at six months; and 1.01 (95% CI 0.86 to 1.19; participants = 316) at one year. Four trials reported adverse events primarily related to gastrointestinal symptoms and sleep disturbance; one trial reported minor adverse event of acne.

AUTHORS' CONCLUSIONS

There is no conclusive evidence of benefit in terms of recovery to normal visual acuity, visual field or contrast sensitivity six months after initiation with either intravenous or oral corticosteroids at the doses evaluated in trials included in this review.

Donepezil increases contrast sensitivity for the detection of objects in scenes

We assessed the effects of donepezil, a drug that stimulates cholinergic transmission, and scopolamine, an antagonist of cholinergic transmission, on contrast sensitivity. 30 young male participants were tested under three treatment conditions: placebo, donepezil, and scopolamine in a random order. Pairs of photographs varying in contrast were displayed left and right of fixation for 50 ms. Participants were asked to locate the scene containing an animal. Accuracy was better under donepezil than under scopolamine, particularly for signals of high intensity (at higher levels of contrast). A control experiment showed that the lower performance under scopolamine did not result from the mydriasis induced by scopolamine. The results suggest that cholinergic stimulation, through donepezil, facilitates signal detection in agreement with studies on animals showing that the pharmacological activation of cholinergic receptors controls the gain in the relationship between the stimulus contrast (intensity of the visual input) and visual response. As Alzheimer disease is associated to depletion in acetylcholine, and there is evidence of deficits in contrast sensitivity in Alzheimer, it might be interesting to integrate such rapid and sensitive visual tasks in the biomarkers at early stage of drug development.

Exposure to organic solvents used in dry cleaning reduces low and high level visual function

PURPOSE

To investigate whether exposure to occupational levels of organic solvents in the dry cleaning industry is associated with neurotoxic symptoms and visual deficits in the perception of basic visual features such as luminance contrast and colour, higher level processing of global motion and form (Experiment 1), and cognitive function as measured in a visual search task (Experiment 2).

METHODS

The Q16 neurotoxic questionnaire, a commonly used measure of neurotoxicity (by the World Health Organization), was administered to assess the neurotoxic status of a group of 33 dry cleaners exposed to occupational levels of organic solvents (OS) and 35 age-matched non dry-cleaners who had never worked in the dry cleaning industry. In Experiment 1, to assess visual function, contrast sensitivity, colour/hue discrimination (Munsell Hue 100 test), global motion and form thresholds were assessed using computerised psychophysical tests. Sensitivity to global motion or form structure was quantified by varying the pattern coherence of global dot motion (GDM) and Glass pattern (oriented dot pairs) respectively (i.e., the percentage of dots/dot pairs that contribute to the perception of global structure). In Experiment 2, a letter visual-search task was used to measure reaction times (as a function of the number of elements: 4, 8, 16, 32, 64 and 100) in both parallel and serial search conditions.

RESULTS

Dry cleaners exposed to organic solvents had significantly higher scores on the Q16 compared to non dry-cleaners indicating that dry cleaners experienced more neurotoxic symptoms on average. The contrast sensitivity function for dry cleaners was significantly lower at all spatial frequencies relative to non dry-cleaners, which is consistent with previous studies. Poorer colour discrimination performance was also noted in dry cleaners than non dry-cleaners, particularly along the blue/yellow axis. In a new finding, we report that global form and motion thresholds for dry cleaners were also significantly higher and almost double than that obtained from non dry-cleaners. However, reaction time performance on both parallel and serial visual search was not different between dry cleaners and non dry-cleaners.

CONCLUSIONS

Exposure to occupational levels of organic solvents is associated with neurotoxicity which is in turn associated with both low level deficits (such as the perception of contrast and discrimination of colour) and high level visual deficits such as the perception of global form and motion, but not visual search performance. The latter finding indicates that the deficits in visual function are unlikely to be due to changes in general cognitive performance.

[The Spatial-Frequency Characteristics of the Visual System in Schizophrenia]

In order to determine the spatial-frequancy characteristics of the visual system of healthy subjects and patients with schizophrenia, we used the contrast comparison of two Gabor gratings with sinusoidal distribution of brightness. The Gabor gratings have low, medium or high spatial frequencies; the neurons of magnocellular and parvocellular channels are sensitive to these frequencies to different extents. We found an increase in sensitivity to the contrast when comparing the gratings with low frequencies (to which magnocellular channels are most sensitive) in the patients with first-episode schizophrenia who had not receive long-term antipsychotic treatment, as compared with the control group. On the contrary, the sensitivity to the gratings with medium and high spatial frequencies in this group of patients was lower, as well as in patients with first-episode schizophrenia who had received long-term treatment. The patients with chronic schizophrenia showed a decrease in contrast sensitivity in all tested ranges of frequencies. We obtained supplementary evidence of the enhancement of internal noise in the visual system of the patients with schizophrenia. The results help us to explain the clinical data on the development of visual perceptual diorders at different stages of schizophrenia.

A randomized placebo-controlled study on the effects of lutein and zeaxanthin on visual processing speed in young healthy subjects

Speed of processing is a particularly important characteristic of the visual system. Often a behavioral reaction to a visual stimulus must be faster than the conscious perception of that stimulus, as is the case with many sports (e.g., baseball). Visual psychophysics provides a relatively simple and precise means of measuring visual processing speed called the temporal contrast sensitivity function (tCSF). Past study has shown that macular pigment (a collection of xanthophylls, lutein (L), meso-zeaxanthin (MZ) and zeaxanthin (Z), found in the retina) optical density (MPOD) is positively correlated with the tCSF. In this study, we found similar correlations when testing 102 young healthy subjects. As a follow-up, we randomized 69 subjects to receive a placebo (n=15) or one of two L and Z supplements (n=54). MPOD and tCSF were measured psychophysically at baseline and 4months. Neither MPOD nor tCSF changed for the placebo condition, but both improved significantly as a result of supplementation. These results show that an intervention with L and Z can increase processing speed even in young healthy subjects.

[The frequency-contrast sensitivity of visual stimulus perception in patients with schizophrenia with the therapy of atypical and typical antipsychotic drugs]

We studied the effect of typical and atypical antipsychotics drag treatment on the perception of visual stimulus which activates preferentially different visual channels. We recorded contrast sensitivity in normal and schizophrenic patients. Elements presented with Gabor-like gratings with sinusoidal distribution of brightness, spatial frequency: 0.4 cycles/degree, 3.6 and 17.9 cycles/degree. Patients were divided into two groups. One group--patients treated with atypical antipsychotics, and the second group--patients treated with typical antipsychotics drags. Registered a decline compared with the normal contrast sensitivity for low and medium spatial frequencies. We observed significant difference between two groups of patients in the range of low spatial frequencies.

Cholinesterase inhibitor, donepezil, improves visual contrast detectability in freely behaving rats

Acetylcholine (ACh) modulates neuronal activities in extensive brain regions to play an essential role in various brain functions including attention, learning and memory, and cognition. Although ACh is known to modulate information processing in the primary visual cortex (V1) in many species including rodent, its functional role in visual ability has remained unknown. We examined whether and how ACh influences behavioral contrast detectability in rat. The detectability was assessed as the contrast sensitivity (CS) to a grating stimulus. Measurements were performed in a two-alternative forced-choice task combined with a staircase method in freely behaving rats. The contrast sensitivity function of rats under the no drug condition showed a low-pass spatial frequency (SF) tuning peaking at 0.1 cycles/degree (cpd) of SF (SF(peak)) that bottomed at 0.5 cpd (SF(bottom)), which was sensitive to the stimulus size, but to neither the temporal frequency nor orientation of the stimulus. The stimulus size was correlated with the CS only at the low SF range. The effect of donepezil on the size- and SF-dependency of the CS was examined using three stimulus conditions: an easy detectability condition with large grating at SF(peak), a difficult detectability condition with small grating at SF(peak), and an upper limit SF condition with large grating at SF(bottom). Donepezil improved the CS at SF(peak), especially in the difficult detectability condition. Therefore, we conclude that ACh plays an important role in enhancing behavioral CS at sensitive SF ranges, but not in improving the upper limit of SF.

[The contrast sensitivity in schizophrenia with different durations disease]

We recorded contrast sensitivity in normal and schizophrenic patients. We presented Gabor gratings with sinusoidal distribution of brightness, with the spatial frequency: 0.4 cycles/degree, 3.6 and 17.9 cycles/degree. Taken together patients with schizophrenia compared to the healthy subjects showed a decline of contrast sensitivity at low and medium spatial frequencies. We measured the influence of duration of illness and type of treatment on contrast sensitivity. Patients with schizophrenia less than 10 years, showed a decrease of contrast sensitivity only at low spatial frequencies, while patients suffered with schizophrenia for more than 10 years--at low, medium and high spatial frequencies. Persons with schizophrenia less than 10 years receiving treatment with atypical antipsychotics, show a decrease in contrast sensitivity at low spatial frequencies, while treated with typical antipsychotics--in the low and high spatial frequencies.

Prenatal and early childhood exposure to tetrachloroethylene and adult vision

BACKGROUND

Tetrachloroethylene (PCE; or perchloroethylene) has been implicated in visual impairments among adults with occupational and environmental exposures as well as children born to women with occupational exposure during pregnancy.

OBJECTIVES

Using a population-based retrospective cohort study, we examined the association between prenatal and early childhood exposure to PCE-contaminated drinking water on Cape Cod, Massachusetts, and deficits in adult color vision and contrast sensitivity.

METHODS

We estimated the amount of PCE that was delivered to the family residence from participants' gestation through 5 years of age. We administered to this now adult study population vision tests to assess acuity, contrast sensitivity, and color discrimination.

RESULTS

Participants exposed to higher PCE levels exhibited lower contrast sensitivity at intermediate and high spatial frequencies compared with unexposed participants, although the differences were generally not statistically significant. Exposed participants also exhibited poorer color discrimination than unexposed participants. The difference in mean color confusion indices (CCI) was statistically significant for the Farnsworth test but not Lanthony's D-15d test [Farnsworth CCI mean difference = 0.05, 95% confidence interval (CI): 0.003, 0.10; Lanthony CCI mean difference = 0.07, 95% CI: -0.02, 0.15].

CONCLUSIONS

Prenatal and early childhood exposure to PCE-contaminated drinking water may be associated with long-term subclinical visual dysfunction in adulthood, particularly with respect to color discrimination. Further investigation of this association in similarly exposed populations is necessary.

Long-term occupational exposure to organic solvents affects color vision, contrast sensitivity and visual fields

The purpose of this study was to evaluate the visual outcome of chronic occupational exposure to a mixture of organic solvents by measuring color discrimination, achromatic contrast sensitivity and visual fields in a group of gas station workers. We tested 25 workers (20 males) and 25 controls with no history of chronic exposure to solvents (10 males). All participants had normal ophthalmologic exams. Subjects had worked in gas stations on an average of 9.6±6.2 years. Color vision was evaluated with the Lanthony D15d and Cambridge Colour Test (CCT). Visual field assessment consisted of white-on-white 24–2 automatic perimetry (Humphrey II-750i). Contrast sensitivity was measured for sinusoidal gratings of 0.2, 0.5, 1.0, 2.0, 5.0, 10.0 and 20.0 cycles per degree (cpd). Results from both groups were compared using the Mann–Whitney U test. The number of errors in the D15d was higher for workers relative to controls (p<0.01). Their CCT color discrimination thresholds were elevated compared to the control group along the protan, deutan and tritan confusion axes (p<0.01), and their ellipse area and ellipticity were higher (p<0.01). Genetic analysis of subjects with very elevated color discrimination thresholds excluded congenital causes for the visual losses. Automated perimetry thresholds showed elevation in the 9°, 15° and 21° of eccentricity (p<0.01) and in MD and PSD indexes (p<0.01). Contrast sensitivity losses were found for all spatial frequencies measured (p<0.01) except for 0.5 cpd. Significant correlation was found between previous working years and deutan axis thresholds (rho = 0.59; p<0.05), indexes of the Lanthony D15d (rho = 0.52; p<0.05), perimetry results in the fovea (rho = −0.51; p<0.05) and at 3, 9 and 15 degrees of eccentricity (rho = −0.46; p<0.05). Extensive and diffuse visual changes were found, suggesting that specific occupational limits should be created.

Corticosteroids for treating optic neuritis

BACKGROUND

Optic neuritis is an inflammatory disease of the optic nerve. It occurs more commonly in women than in men. Usually presenting with an abrupt loss of vision, recovery of vision is almost never complete. Closely linked in pathogenesis to multiple sclerosis, it may be the initial manifestation for this condition. In certain patients, no underlying cause can be found.

OBJECTIVES

To assess the effects of corticosteroids on visual recovery of patients with acute optic neuritis.

SEARCH METHODS

We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (The Cochrane Library 2012, Issue 1), MEDLINE (January 1950 to February 2012), EMBASE (January 1980 to February 2012), Latin American and Caribbean Literature on Health Sciences (LILACS) (January 1982 to February 2012), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrials.gov) and the WHO International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). There were no date or language restrictions in the electronic searches for trials. The electronic databases were last searched on 21 February 2012. We also searched reference lists of identified trial reports to find additional trials.

SELECTION CRITERIA

We included randomized trials that evaluated corticosteroids, in any form, dose or route of administration, in people with acute optic neuritis.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted the data on methodological quality and outcomes for analysis.

MAIN RESULTS

We included six randomized trials which included a total of 750 participants. Two trials evaluated low dose oral corticosteroids while one trial evaluated low dose intravenous corticosteroids across two treatment arms and two trials evaluated a higher dose of intravenous corticosteroids. One three-arm trial evaluated low-dose oral corticosteroids and high-dose intravenous corticosteroids against placebo. Trials evaluating oral corticosteroids compared varying doses of corticosteroids with placebo. Hence, we did not conduct a meta-analysis of such trials. In a meta-analysis of trials evaluating corticosteroids with total dose greater than 3000 mg administered intravenously, the relative risk of normal visual acuity with intravenous corticosteroids compared with placebo was 1.06 (95% confidence interval (CI) 0.89 to 1.27) at six months and 1.06 (95% CI 0.92 to 1.22) at one year. The risk ratio of normal contrast sensitivity for the same comparison was 1.10 (95% CI 0.92 to 1.32) at six months follow up. We did not conduct a meta-analysis for this outcome at one year follow up since there was substantial statistical heterogeneity. The risk ratio of normal visual field for this comparison was 1.08 (95% CI 0.96 to 1.22) at six months and 1.02 (95% CI 0.86 to 1.20) at one year. Quality of life was assessed and reported in one trial.

AUTHORS' CONCLUSIONS

There is no conclusive evidence of benefit in terms of recovery to normal visual acuity, visual field or contrast sensitivity with either intravenous or oral corticosteroids at the doses evaluated in trials included in this review.

Testosterone induces off-line perceptual learning

RATIONALE

Perceptual learning operates on distinct timescales. How different neuromodulatory systems impact on learning across these different timescales is poorly understood.

OBJECTIVES

Here, we test the causal impact of a novel influence on perceptual learning, the androgen hormone testosterone, across distinct timescales.

METHODS

In a double-blind, placebo- controlled, cross-over study with testosterone, subjects undertook a simple contrast detection task during training sessions on two separate days.

RESULTS

On placebo, there was no learning either within training sessions or between days, except for a fast, rapidly saturating, improvement early on each testing day. However, testosterone caused "off-line" learning, with no learning seen within training sessions, but a marked performance improvement over the days between sessions. This testosterone-induced learning occurred in the absence of changes in subjective confidence or introspective accuracy.

CONCLUSIONS

Our findings show that testosterone influences perceptual learning on a timescale consistent with an influence on "off-line" consolidation processes.

Visual contrast sensitivity in children exposed to tetrachloroethylene

This study examined relationships between indoor air, breath, and blood tetrachloroethylene (perc) levels and visual contrast sensitivity (VCS) among adult and child residents of buildings with or without a colocated dry cleaner using perc. Decreasing trends in proportions of adults or children with maximum VCS scores indicated decreased VCS at a single spatial frequency (12 cycles per degree [cpd]) among children residing in buildings with colocated dry cleaners when indoor air perc level averaged 336 μg/m³; breath perc level averaged 159.5 μg/m³; and blood perc level averaged 0.51 μg/L. Adjusted logistic regression indicated that increases in indoor air, breath, and blood perc levels among all child participants significantly increased the odds for decreased VCS at 12 cpd. Adult VCS was not significantly decreased by increasing indoor air, breath, or blood perc level. These results suggest that elevated residential perc exposures may alter children's VCS, a possible subclinical central nervous system effect.

NMDA receptor contributions to visual contrast coding

In the retina, it is not well understood how visual processing depends on AMPA- and NMDA-type glutamate receptors. Here we investigated how these receptors contribute to contrast coding in identified guinea pig ganglion cell types in vitro. NMDA-mediated responses were negligible in ON alpha cells but substantial in OFF alpha and delta cells. OFF delta cell NMDA receptors were composed of GluN2B subunits. Using a novel deconvolution method, we determined the individual contributions of AMPA, NMDA, and inhibitory currents to light responses of each cell type. OFF alpha and delta cells used NMDA receptors for encoding either the full contrast range (alpha), including near-threshold responses, or only a high range (delta). However, contrast sensitivity depended substantially on NMDA receptors only in OFF alpha cells. NMDA receptors contribute to visual contrast coding in a cell-type-specific manner. Certain cell types generate excitatory responses using primarily AMPA receptors or disinhibition.

Vision in depressive disorder

BACKGROUND

Reduced dopaminergic transmission has been implicated in the pathophysiology of major depression. Furthermore, dopaminergic neurotransmission plays an important role in the physiology of visual contrast sensitivity (CS). To test the hypothesis that altered dopaminergic neurotransmission plays a role in major depression we measured contrast sensitivity in patients with major depression and in healthy control subjects.

METHODS

Twenty-eight patients diagnosed with major depressive disorder were compared to 21 age-matched control subjects on their ability to detect a Gabor target with slightly elevated luminance contrast embedded in seven equi-contrast distracters.

RESULTS

Contrast discrimination thresholds were significantly elevated in unmedicated and medicated patients with major depression compared to control subjects, at all pedestal contrast levels tested.

CONCLUSIONS

Contrast discrimination performance is reduced in depressive patients and might reflect a state of altered dopaminergic neurotransmission.

[Time course of changes in contrast sensitivity function after application of antiglaucomatous eyedrops]

PURPOSE

Some antiglaucomatous eyedrops can cause blurred vision after application. Contrast sensitivity after application, however, has not been examined. The purpose of this study was to investigate the influence of antiglaucomatous eyedrops on contrast sensitivity function.

METHODS

In 23 eyes of 23 normal volunteers (34.9 +/- 14.5 years [mean +/- SD]), contrast sensitivity was measured before and 2, 5, 10, and 15 minutes after application of antiglaucomatous eyedrops. Three drugs, timolol maleate ion-activated gel, timolol maleate thermosetting gel, and brinzolamide were tested in this study, and the time course of changes in contrast sensitivity after instillation was statistically analyzed and compared between the drugs.

RESULTS

All drugs significantly reduced contrast sensitivity function (p<0.001). The reduction in contrast sensitivity persisted for approximately 5 minutes after instillation of timolol maleate ion-activated gel and brinzolamide. For timolol maleate thermosetting gel, the reduction in contrast sensitivity lasted for about 10 minutes, but the reduction immediately (two minutes) after instillation was significantly smaller than that of the other two drugs (p<0.05).

CONCLUSIONS

Instillation of these three drugs temporarily degrades contrast sensitivity function, leading to blurred vision, which should be sufficiently explained to patients before treatment with these eyedrops.

Influence of topical bimatoprost on macular thickness and volume in glaucoma patients with phakic eyes

BACKGROUND

In light of concern about the possible relation between the extensive clinical use of prostaglandin analogues and the development of retinal disorders such as cystoid macular edema, this study investigated the influence of topical application of bimatoprost 0.03% on macular thickness and volume in glaucoma patients with phakic eyes.

METHODS

A total of 40 eyes in 22 patients with primary open-angle glaucoma or normal-tension glaucoma were evaluated in this study. Optical coherence tomography images were taken before initiation of bimatoprost application and after 1, 2, and 3 months of treatment. In addition, best-corrected visual acuity (BCVA) and intraocular pressure (IOP) were measured, and contrast sensitivity tests and fundus examinations were performed. Changes in various parameters, including macular thickness and volume, were analyzed.

RESULTS

BCVA and contrast sensitivity did not change from baseline over the treatment period. IOP declined by 20% to 25% from baseline for 1 month before stabilizing. Macular thickness and volume did not increase significantly during the 3 months.

INTERPRETATION

Topical application of bimatoprost does not induce clinical or structural changes in the macula, at least in glaucoma patients with phakic eyes. Moreover, bimatoprost effectively lowered IOP without causing macular disorders such as cystoid macular edema.

Electrophysiological evidence for impairment of contrast sensitivity in mercury vapor occupational intoxication

Contrast sensitivity (CS) was evaluated in 41 former workers from a lamp manufacturing plant who were on disability retirement due to exposure to mercury and 14 age-matched controls. The CS was measured monocularly using the sweep visual evoked potential (sVEP) paradigm at 6 spatial frequencies (0.2, 0.8, 2.0, 4.0, 15.0, and 30 cpd). Statistical difference (p<0.05) was found between the controls and the patient right and left eyes for 2.0 and 4.0 cpd. According the results in those spatial frequencies the eyes were classified in best and worst. Statistical differences were found between the controls and the best eyes for 2.0 and 4.0 cpd and for 0.8, 2.0, and 4.0 cpd for their worst eyes. No correlation was found between CS results and the time of exposure (mean=8.9 yr+/-4.1), time away from the mercury source (mean=6.0 yr+/-3.9), urinary mercury level at the time of work (mean=40.6 microg/g+/-36.3) or with the mercury level at the CS measurement time (mean=1.6 microg/g+/-1.1). We show the first evidence of a permanent impairment in CS measured objectively with the sVEP. Our data complement the previous psychophysical works reporting a diffuse impairment in the CS function showing a CS reduction in the low to middle spatial frequencies. In conclusion, non-reversible CS impairment was found in occupational exposure to mercury vapor. We suggest that CS measurement should be included in studies of the mercury effects of occupational exposure.

Contrast sensitivity is reduced in children with infantile spasms

PURPOSE

To investigate whether visual deficits in children with infantile spasm (IS) are the result of seizure activity or of treatment with the anticonvulsant drug vigabatrin (VGB).

METHODS

Vision function was determined in three experiments by determining peak contrast sensitivity (CS) and grating acuity (GA) with the sweep visual evoked potential. Cross-sectional study A: 34 children, including 11 patients with childhood epilepsy with exposure to VGB for at least 6 months, 10 with childhood epilepsy exposed to antiepileptic drugs other than VGB, and 13 normally developing children. Cross-sectional study B: 32 children, including 16 with IS naïve to VGB and 16 normally developing children. Longitudinal study: seven children with IS naïve to VGB, with subsequent follow-up 5 to 10 months after starting VGB.

RESULTS

In cross-sectional study A, the median CS was reduced by 0.5 log units (P = 0.025) in children with epilepsy exposed to VGB compared with those exposed to other antiepileptic drugs and normally developing children. In cross-sectional study B, the median CS was reduced by 0.25 log units (P = 0.0015) in children with IS (VGB naïve) compared with normally developing children. Longitudinal assessment showed no decrease in CS in children with IS who were followed up 5 to 10 months after starting VGB. There was no difference in GA among groups in any of the experiments.

CONCLUSIONS

Patients with IS have CS deficits, but a sparing of GA. This deficit is present before VGB treatment and does not worsen with treatment onset. Results suggest that visual dysfunction is largely the result of the seizures themselves.

Visual outcome of a cohort of children with neurofibromatosis type 1 and optic pathway glioma followed by a pediatric neuro-oncology program

We evaluated the visual outcome of a cohort of children with neurofibromatosis type 1 (NF1) and optic pathway glioma (OPG) treated according to standardized therapeutic guidelines. The study population consisted of all consecutive patients with NF1 and OPG referred to a specialized pediatric neuro-oncology program between 1994 and 2004. Treatment was instituted only in cases of progressive disease or clinical deterioration. Treatment modalities were chemotherapy (based on vincristine/carboplatin) for children younger than 5 years and radiotherapy for all others. Ten boys and 10 girls (seven with a positive family history) entered the trial (median age at diagnosis of OPG, 29 months). At a median follow-up time of 78 months, seven patients had been treated with chemotherapy only, four with radiotherapy, and four with chemotherapy plus radiotherapy. Five patients were observed only. Currently, 18 are alive and two have died. Eight patients were treated for progressive visual loss in the face of stable disease, five for tumor volume increase without visual deterioration, and two for symptomatic tumor volume increase. At referral, six children had a visual acuity (VA) of < 30% in both eyes; eight children had 100% VA bilaterally. At referral, the visual field (VF) could be assessed in three children: One had VF loss in both eyes, one had VF loss in one eye, and one had normal VF. At last follow-up, eight children had VA < 20% in both eyes; only two children had 100% VA in both eyes. Among 11 children who had some visual function, three had VF loss in one eye and three in both eyes, and five had an intact VF. Contrast and color sensitivity were abnormal in seven and six patients, respectively. Thirteen children fell into the WHO hypovision category. In summary, among the 15 children treated, one had a definitive and two a mild improvement in VA. In conclusion, the visual outcome of this selected cohort of NF1 patients with OPG is unsatisfactory. A critical reappraisal of the therapeutic strategy adopted is needed.

Visual behavior of adult goldfish with regenerating retina

To determine whether regenerating neural pathways can support visual behavior, adult goldfish (Carassius auratus) were injected intraocularly with ouabain and tested for the presence of reflexive visual behaviors (dorsal light reflex and optokinetic nystagmus) and the ability to respond to visual stimuli in a classical conditioning paradigm. All visual behaviors were absent or greatly diminished until 8 to 10 weeks, when retinal layering had returned. At 10 weeks post-ouabain, reflexive behaviors to supra-threshold stimuli were near normal; however the ability to detect supra-threshold stimuli in the conditioning paradigm did not recover until 13 weeks. Absolute dark-adapted threshold and light-adapted spectral sensitivity measured at 13 to 17 weeks were abnormal: Dark-adapted threshold was elevated by 1.5 log units and light-adapted spectral sensitivity was markedly narrower than normal. No responses to 50% contrast sinusoidal gratings could be obtained through ouabain-treated eyes using the classical conditioning technique, even though responses through the untreated eye remained. Results demonstrate that: (a) visually mediated behaviors return in goldfish with ouabain-treated retinas; (b) the time course of recovery of reflexive responses in luminance and spatial domains parallels return of ERG function and of tectal activity; and (c) visual function that is mediated by regenerating retina appears not to be as sensitive as vision via normally developed retinal pathways.

Natalizumab reduces visual loss in patients with relapsing multiple sclerosis

OBJECTIVE

To examine the effects of natalizumab on low-contrast letter acuity as a prespecified tertiary endpoint in two randomized clinical trials and to evaluate the usefulness of low-contrast letter acuity testing as a candidate test of visual function in multiple sclerosis (MS).

METHODS

AFFIRM and SENTINEL were randomized, double-blind, placebo-controlled, multicenter, phase 3 clinical trials of natalizumab in relapsing MS. Natalizumab was evaluated as monotherapy in AFFIRM and as add-on to interferon beta-1a in SENTINEL. Vision testing was performed at 100% contrast (visual acuity) and low-contrast (2.5% and 1.25%).

RESULTS

The risk of clinically significant visual loss (predefined as a two-line worsening of acuity sustained over 12 weeks) at the lowest contrast level (1.25%) was reduced in the natalizumab treatment arms by 35% in AFFIRM (hazard ratio = 0.65; 95% CI: 0.47 to 0.90; p = 0.008) and by 28% in SENTINEL (hazard ratio = 0.72; 95% CI: 0.54 to 0.98; p = 0.038, Cox proportional hazards models). Mean changes in vision scores from baseline were also significantly different, reflecting worsening in non-natalizumab groups.

CONCLUSIONS

Natalizumab reduces visual loss in patients with relapsing multiple sclerosis. Low-contrast acuity testing has the capacity to demonstrate treatment effects and is a strong candidate for assessment of visual outcomes in future multiple sclerosis trials.

Purified high-dose anthocyanoside oligomer administration improves nocturnal vision and clinical symptoms in myopia subjects

The aim of the present study was to determine the effect of purified high-dose anthocyanoside oligomer administration on nocturnal visual function and clinical symptoms in low-to-moderate myopia subjects. The study was a randomized, double-blind, placebo-controlled trial and involved sixty subjects with asthenopia and refractive errors between −1·00 and −8·00 diopters in both eyes. Thirty subjects were administered a purified high-dose anthocyanoside oligomer (100 mg tablet comprising 85 % anthocyanoside oligomer), and thirty were given a placebo in tablet form twice daily for 4 weeks. Prior to the treatment, the placebo and anthocyanoside groups were similar in terms of age and contrast sensitivity. Before and after treatment, subjects completed a questionnaire to determine their clinical symptoms and were also assessed for nocturnal visual function using contrast sensitivity testing. Questionnaire data analysis showed that, following treatment, twenty-two (73·3 %) anthocyanoside subjects showed improved symptoms, whereas only one placebo subject showed an improvement (Fisher's exact test,P<0·0001). Contrast sensitivity levels according to each cycle per degree significantly improved in the anthocyanoside group and remained stable in the placebo group. The mean contrast sensitivity change in the anthocyanoside group was 2·41 (SD) 1·91, compared with −0·66 (SD) 2·66 dB for the placebo group (unpaired Student'sttest,P<0·0001). At all cycle per degree levels, contrast sensitivity changes in the anthocyanoside group were better than in the placebo group (unpaired Student'sttest,P<0·05). The present data show that the administration of anthocyanoside oligomer appears to improve subjective symptoms and objective contrast sensitivity in myopia subjects with asthenopia.

Mercury toxicity in the Amazon: contrast sensitivity and color discrimination of subjects exposed to mercury

We measured visual performance in achromatic and chromatic spatial tasks of mercury-exposed subjects and compared the results with norms obtained from healthy individuals of similar age. Data were obtained for a group of 28 mercury-exposed subjects, comprising 20 Amazonian gold miners, 2 inhabitants of Amazonian riverside communities, and 6 laboratory technicians, who asked for medical care. Statistical norms were generated by testing healthy control subjects divided into three age groups. The performance of a substantial proportion of the mercury-exposed subjects was below the norms in all of these tasks. Eleven of 20 subjects (55%) performed below the norms in the achromatic contrast sensitivity task. The mercury-exposed subjects also had lower red-green contrast sensitivity deficits at all tested spatial frequencies (9/11 subjects; 81%). Three gold miners and 1 riverine (4/19 subjects, 21%) performed worse than normal subjects making more mistakes in the color arrangement test. Five of 10 subjects tested (50%), comprising 2 gold miners, 2 technicians, and 1 riverine, performed worse than normal in the color discrimination test, having areas of one or more MacAdam ellipse larger than normal subjects and high color discrimination thresholds at least in one color locus. These data indicate that psychophysical assessment can be used to quantify the degree of visual impairment of mercury-exposed subjects. They also suggest that some spatial tests such as the measurement of red-green chromatic contrast are sufficiently sensitive to detect visual dysfunction caused by mercury toxicity.

TOZAL Study: an open case control study of an oral antioxidant and omega-3 supplement for dry AMD

Background

The primary objective of this prospective study was to measure the change from baseline in visual function – Best-Corrected Visual Acuity (BCVA) via the Early Treatment Diabetic Retinopathy Study (ETDRS) chart, contrast sensitivity, central 10 degree visual fields and retinal imaging (angiograms and photographs) at 6 months in subjects with atrophic (dry) age-related macular degeneration treated with a targeted nutritional supplement.

Methods

37 mixed gender patients with a mean age of 76.3 +/- 7.8 years were enrolled at 5 independent study sites and received standard of care with a novel formulation of a nutritional supplement. Results were compared to a placebo cohort constructed from the literature that was matched for inclusion and exclusion criteria. A paired t-test was used to test a null hypothesis and a two-sided alpha level of 0.05 was used to determine statistical significance.

Results

76.7% of subjects receiving the nutritional supplement demonstrated stabilization or improvement of BCVA at 6 months. Subjects gained an average of 0.0541 logMAR or one-half of a line of visual acuity (VA) over the 6-month period. There was a statistically significant improvement in VA from baseline with P = .045. The results provide strong evidence that the treatment being studied produces an improvement in VA.

Conclusion

Treatment with this unique nutritional supplement increased VA above the expected baseline decrease in the majority of patients in this population with dry macular degeneration. The results of the TOZAL study agree with the LAST and CARMIS studies and are predictive for positive visual acuity outcomes in the AREDS II trial. However, patients will likely require supplementation for longer than 6 months to effect changes in additional visual parameters.

Effect of lutein and antioxidant dietary supplementation on contrast sensitivity in age-related macular disease: a randomized controlled trial

OBJECTIVE

The aim of the study is to determine the effect of lutein combined with vitamin and mineral supplementation on contrast sensitivity in people with age-related macular disease (ARMD).

DESIGN

A prospective, 9-month, double-masked randomized controlled trial.

SETTING

Aston University, Birmingham, UK and a UK optometric clinical practice.

SUBJECTS

Age-related maculopathy (ARM) and atrophic age-related macular degeneration (AMD) participants were randomized (using a random number generator) to either placebo (n=10) or active (n=15) groups. Three of the placebo group and two of the active group dropped out.

INTERVENTIONS

The active group supplemented daily with 6 mg lutein combined with vitamins and minerals. The outcome measure was contrast sensitivity (CS) measured using the Pelli-Robson chart, for which the study had 80% power at the 5% significance level to detect a change of 0.3 log units.

RESULTS

The CS score increased by 0.07+/-0.07 and decreased by 0.02+/-0.18 log units for the placebo and active groups, respectively. The difference between these values is not statistically significant (z=-0.903, P=0.376).

CONCLUSION

The results suggest that 6 mg of lutein supplementation in combination with other antioxidants is not beneficial for this group. Further work is required to establish optimum dosage levels.

Corticosteroids for treating optic neuritis

BACKGROUND

Optic neuritis is an inflammatory disease of the optic nerve. It occurs more commonly in women than in men. Usually presenting with an abrupt loss of vision, recovery of vision is almost never complete. Closely linked in pathogenesis to multiple sclerosis, it may be the initial manifestation for this condition. In certain patients, no underlying cause can be found.

OBJECTIVES

To assess the effects of corticosteroids on visual recovery of patients with acute optic neuritis.

SEARCH STRATEGY

We searched the Cochrane Controlled Trials Register (CENTRAL) (which contains the Cochrane Eyes and Vision Group Trials Register) (issue 4, 2005), MEDLINE (1966 to December 2005), EMBASE (1980 to January 2006), NNR (issue 4, 2006), LILACS and reference lists of identified trial reports.

SELECTION CRITERIA

We included randomized trials that evaluated corticosteroids, in any form, dose or route of administration, in people with acute optic neuritis.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted the data on methodological quality and outcomes for analysis.

MAIN RESULTS

We included five randomized trials which included a total of 729 participants. Two trials evaluated low dose oral corticosteroids and two trials evaluated a higher dose of intravenous corticosteroids. One three-arm trial evaluated low-dose oral corticosteroids and high-dose intravenous corticosteroids against placebo. Trials evaluating oral corticosteroids compared varying doses of corticosteroids with placebo. Hence, we did not conduct a meta-analysis of such trials. In a meta-analysis of trials evaluating corticosteroids with total dose greater than 3000 mg administered intravenously, the relative risk of normal visual acuity with intravenous corticosteroids compared with placebo was 1.06 (95% CI 0.89 to 1.27) at six months and 1.06 (95% CI 0.92 to 1.22) at one year. The risk ratio of normal contrast sensitivity for the same comparison was 1.10 (95% CI 0.92 to 1.32) at six months follow up. We did not conduct a meta-analysis for this outcome at one year follow up since there was substantial statistical heterogeneity. The risk ratio of normal visual field for this comparison was 1.08 (95% CI 0.96 to 1.22) at six months and 1.02 (95% CI 0.86 to 1.20) at one year. Quality of life was assessed and reported in one trial.

AUTHORS' CONCLUSIONS

There is no conclusive evidence of benefit in terms of recovery to normal visual acuity, visual field or contrast sensitivity with either intravenous or oral corticosteroids at the doses evaluated in trials included in this review.

Recognition of category-related visual stimuli in Parkinson's disease: Before and after pharmacological treatment

Visual-sensory dysfunctions and semantic processing impairments are widely reported in Parkinson's disease (PD) research. The present study investigated the category-specific deficit in object recognition as a function of both the semantic category and spatial frequency content of stimuli. In the first experiment, the role of dopamine in object-recognition processing was assessed by comparing PD drug naïve (PD-DN), PD receiving levodopa treatment (PD-LD), and control subjects. Experiment 2 consisted of a retest session for PD drug naïve subjects after a period of pharmacological treatment. All participants completed an identification task which displayed animals and tools at nine levels of filtering. Each object was revealed in a sequence of frames whereby the object was presented at increasingly less-filtered images up to a complete version of the image. Results indicate an impaired identification pattern for PD-DN subjects solely for animal category stimuli. This differential pharmacological therapy effect was also confirmed at retest (experiment 2). Thus, our data suggest that dopaminergic loss has a specific role in category-specific impairment. Two possible hypotheses are discussed that may account for the defective recognition of semantically different objects in PD.

Single retinal changing contrast (third) detector elicits NMDA receptor response and higher activity level of frog tectum neuron network

The present study was designed to explore whether a discharge of a certain type of frog retinal ganglion cell [likely changing contrast (third) detector] can evoke NMDA response in frog tectum neurons and higher level of activity of tectal neuron network. Discharge of a single retinal ganglion cell was elicited by electrical stimulation of the retina. Evoked electrical activity of the tectum was recorded by the carbon-fiber microelectrode brought into the optic fiber layer F. We show that: (1) strong discharge of a frog individual retinal ganglion cell (third detector) has evoked NMDA response of tectal neurons and higher level of tectal neuron network activity characterized by prominent suprathreshold excitation of efferent neurons. Consequently, the firing of only one retinal ganglion cell (third detector) could lead to the activation of the tectobulbospinal tract and motor reaction. (2) The excitation of a retinotectal fiber of the first kind (axon of third detector) gave rise to the same effects as activation of a retinotectal fiber of the second kind (axon of fifth detector): the suprathreshold excitation of recurrent and efferent tectal neurons, the slow depolarizing potential (seen as the sNW), and the NMDA receptor activation were observed. However, stronger excitation (longer bursts of action potentials) was needed to evoke those effects in the considered case of the retinotectal input of the first kind. This difference could be attributed to the lower quantal size of neurotransmitter release in synapses of the retinotectal input of the first than second kind.

Using contrast sensitivity to estimate the cost-effectiveness of verteporfin in patients with predominantly classic age-related macular degeneration

AIMS

To re-evaluate the cost-effectiveness of photodynamic therapy with verteporfin (Visudyne, Novartis AG, Switzerland) in patients with predominantly classic and classic choroidal neovascularization (CNV) owing to age-related macular degeneration (AMD), using new evidence on the impact of contrast sensitivity on health status.

METHOD

A health economic model is used to synthesise the evidence on contrast sensitivity and treatment rates from the TAP Investigation with health state utilities and costs. Impairment of visual function is estimated using a Markov model to predict transitions between states of contrast sensitivity. Each state is associated with costs and a health state utility. Total expected costs and benefits for a cohort of patients over a defined number of cycles are calculated. The expected health state utility for each disease state was estimated using results from a study of 209 patients with AMD in Sheffield. The model includes the costs associated with treatment and monitoring in the verteporfin treatment arm and costs offset by delaying the deterioration of visual function.

RESULTS

Beyond 3 years, the annual costs of the verteporfin arm are estimated to be less than the annual costs of the control arm, owing to the cost associated with higher blindness prevalence in the control arm. Over time, the results show that both the incremental utility and cost decreases. By 10 years, the estimated incremental cost-effectiveness is approximately pound20 996 per Quality-Adjusted Life Years.

CONCLUSION

The results of this study suggest that the verteporfin therapy in the treatment for patients with predominantly classic and classic CNV owing to AMD is encouraging.

The effects of artificial tear application on contrast sensitivity in dry and normal eyes

PURPOSE

To investigate the effects of artificial tear application on contrast sensitivity in dry and normal eyes.

METHODS

A total of 55 patients with normal (10/10) corrected or uncorrected visual acuity referring to GATA Gulhane Military Medical Academy Haydarpasa Ophthalmology Outpatient Clinic were evaluated in regard to dry eye diagnostic criteria, and assigned into the dry eye group (Group 1; 35 patients) and the control group (Group 2; 20 patients). All patients were given a contrast sensitivity testing at low and high spatial frequencies using the gradual contrast sensitivity chart before and at 5 minutes after application of artificial tears, and the two groups were compared. Wilcoxon test was used in statistical analysis, accepting a p value of <0.05 as significant.

RESULTS

In the dry eye group, there was a statistically significant increase in contrast sensitivity scores both at low and high frequencies after application of artificial tears (p<0.05). In the control group, although there was a significant increase in low frequency scores after artificial tear application (p< 0.05), there was not a significant change in high frequency scores (p>0.05).

CONCLUSIONS

The decreased contrast sensitivity in dry eyes improves with application of artificial tears. Therefore, the impeded quality of vision seen in dry eye patients could be restored closer to normal with artificial tear therapy. Besides, contrast sensitivity testing could be used in the follow-up of artificial tear therapy.

Supplementation with the carotenoids lutein or zeaxanthin improves human visual performance

BACKGROUND

Macular pigment (MP) is found in diurnal primate species when vision spans a range of ambient illumination and is mediated by cone and rod photoreceptors. The exact role of MP remains to be determined. In this study we investigate two new hypotheses for possible MP functions.

OBJECTIVE

As MP absorption coincides partly with that of rhodopsin, MP may reduce rod signal effectiveness in the mesopic range, thus extend the usefulness of cone-mediated vision into the mesopic range. Forward light scatter in the eye can reduce retinal image contrast. If blue light contributes significantly to intraocular scatter, selective blue light absorption by MP could reduce the effects of scatter.

DESIGN

We investigated 34 subjects from a carotenoid supplementation trial. The measurements included high mesopic contrast acuity thresholds (CATs), macular pigment optical density (MPOD), wavefront aberrations, and scattered light. The measurements were made after 6 months of daily supplementation with zeaxanthin (Z, OPTISHARP), lutein (L), a combination of the two (C), or placebo (P), and again after a further 6 months of doubled supplementation.

RESULTS

The data reveal a trend toward lower CATs in all groups supplemented, with a statistically significant improvement in the lutein group (p = 0.001), although there was no correlation with MPOD. Light scattering in the eye and the root-mean-square wavefront aberrations show decreasing trends as a result of supplementation, but no correlation with MPOD.

CONCLUSIONS

The results suggest that supplementation with L or Z increases MPOD at the fovea and at 2.5 degrees , and that supplementation can improve CATs at high mesopic levels and hence visual performance at low illumination.

Impairment of contrast sensitivity in long-term lorazepam users

RATIONALE

Oculomotor balance and contrast sensitivity are known to be impaired after an intake of a single dose of lorazepam. To the best of our knowledge, these effects have not been explored in long-term users of lorazepam, despite the potential importance of such deficits in everyday life.

OBJECTIVE

We tested the ophthalmological effects and contrast sensitivity for static stimuli in long-term lorazepam users.

MATERIALS AND METHODS

There were 15 lorazepam users and 15 sex-, age- and education level-matched control subjects tested, using a simple blind procedure.

RESULTS

The ophthalmological effects were scarce, with a discrete exophoria. Visual acuity was preserved. Contrast sensitivity, however, was more markedly impaired, consistent with the effects of an acute dose of lorazepam. The effects were not correlated with anxiety or sedation.

CONCLUSIONS

The results are discussed in terms of their possible impact on everyday life. As visual acuity does not allow the detection of the impairments that are observed in the present study, it is suggested that a more systematic exploration of contrast sensitivity be carried out in long-term users of benzodiazepines.

Lutein supplementation in retinitis pigmentosa: PC-based vision assessment in a randomized double-masked placebo-controlled clinical trial [NCT00029289]

Background

There is no generally accepted medical or surgical treatment to stop the progressive course of retinitis pigmentosa. Previous studies have suggested lutein as a potential treatment with positive effects on macular pigment density. The objective of this study was to examine the effect of lutein supplementation on preservation of visual function in patients with retinitis pigmentosa (RP)

Methods

In a double-masked randomized placebo-controlled phase I/II clinical trial with a cross-over design, 34 adult patients with RP were randomized to two groups. One group, consisted of 16 participants, received lutein supplementation (10 mg/d for 12 wks followed by 30 mg/d) for the first 24 weeks and then placebo for the following 24 weeks, while the other group included 18 participants for whom placebo (24 weeks) was administered prior to lutein. Visual acuity, contrast sensitivity, and central visual field were measured at different illumination levels at baseline and every week using a PC-based test at home.

Results

For visual acuity (VA) at normal illumination level, treatment with lutein reduced logMAR, i.e. improved VA, but this effect was not statistically significant. The changes in normal (100%), low (4%), and very low (0.1%) illumination log CS were not statistically significant (p-values: 0.34, 0.23, and 0.32, respectively). Lutein had a statistically significant effect on visual field (p-value: 0.038) and this effect increased in the model assuming a 6-week delay in effect of lutein. Comparing the development of vision measures against the natural loss expected to occur over the course of 48 weeks, most measures showed reduced decline, and these reductions were significant for normal illumination VA and CS.

Conclusion

These results suggest that lutein supplementation improves visual field and also might improve visual acuity slightly, although these results should be interpreted cautiously. As a combined phase I and II clinical trial, this study demonstrated the efficacy and safety of lutein supplementation.

Prenatal methylmercury exposure affects spatial vision in adult monkeys

Decades of research have demonstrated that exposure to methylmercury (MeHg), a ubiquitous environmental pollutant, can have both early and long-term neurobehavioral consequences in exposed offspring. The present study assessed visual functioning in adult macaque monkeys (Macaca fascicularis) exposed in utero to 0, 50, 70, or 90 microg/kg/day of MeHg hydroxide. Twenty-one full-term, normal birth weight offspring (9 controls, 12 exposed) were tested at approximately 11-14.5 years of age on a visual contrast sensitivity task. A forced-choice tracking procedure was utilized with spatial frequencies of 1, 4, 10, and 20 cycles per degree of visual angle. On each test session, a single spatial frequency was presented across five levels of contrast, each differing by 3 dB. Methylmercury-exposed monkeys exhibited reduced contrast sensitivity thresholds, particularly at the higher spatial frequencies. The degree of visual impairment was not related to MeHg body burden or clearance and almost half of the exposed animals were unimpaired. The results from this study demonstrate that chronic in utero MeHg exposure, at subclinical levels, is associated with permanent adverse effects on spatial vision in adult monkeys.

Presynaptic Mechanism for Slow Contrast Adaptation in Mammalian Retinal Ganglion Cells

Visual neurons, from retina to cortex, adapt slowly to stimulus contrast. Following a switch from high to low contrast, a neuron rapidly decreases its responsiveness and recovers over 5-20 s. Cortical adaptation arises from an intrinsic cellular mechanism: a sodium-dependent potassium conductance that causes prolonged hyperpolarization. Spiking can drive this mechanism, raising the possibility that the same mechanism exists in retinal ganglion cells. We found that adaptation in ganglion cells corresponds to a slowly recovering afterhyperpolarization (AHP), but, unlike in cortical cells, this AHP is not primarily driven by an intrinsic cellular property: spiking was not sufficient to generate adaptation. Adaptation was strongest following spatial stimuli tuned to presynaptic bipolar cells rather than the ganglion cell; it was driven by a reduced excitatory conductance, and it persisted while blocking GABA and glycine receptors, K((Ca)) channels, or mGluRs. Thus, slow adaptation arises from reduced glutamate release from presynaptic (nonspiking) bipolar cells.

Prospective randomized controlled trial of the effect of intracameral vancomycin and gentamicin on macular retinal thickness and visual function following cataract surgery

PURPOSE

To investigate whether the use of vancomycin (20 microg/mL) and gentamicin (8 microg/mL) in the infusion fluid at the time of cataract surgery increases the incidence of macular thickening as measured with optical coherence tomography (OCT) following phacoemulsification.

SETTING

A public teaching hospital in Western Australia.

METHODS

Fourty-one patients (50 eyes) with cataracts between 50 and 85 years of age were randomized to receive no antibiotics in the infusion fluid at the time of cataract surgery (control group) or vancomycin (20 microg/mL) and gentamicin (8 microg/mL) in the infusion fluid (antibiotic group). Optical coherence tomography measurements were performed preoperatively and 1 day and 1 and 5 weeks postoperatively. A significant increase in macular thickness (mean of the central 1.0 mm diameter) on OCT was defined as 15 microm or greater. Five weeks postoperatively, the best corrected Snellen acuity and Pelli-Robson contrast sensitivity were measured.

RESULTS

Twenty-five percent in the control group and 38% in the antibiotic group had a significant increase in macular thickness measured on OCT 5 weeks postoperatively (P = .34). The mean contrast sensitivity of patients with increased macular thickness on OCT was 1.26, and in those with no change it was 1.43 (P = .001).

CONCLUSIONS

The use of intracameral vancomycin (20 microg/mL) and gentamicin (8 microg/mL) at the time of cataract surgery had no significant effect on macular thickness or visual function postoperatively. Overall, 31% of eyes showed an increase of 15 microm or greater in central retinal thickness. These patients had significantly reduced contrast sensitivity.

A double-blind, randomized trial of IV immunoglobulin treatment in acute optic neuritis

OBJECTIVE

To investigate if IV immunoglobulin (IVIG) treatment in the acute phase of optic neuritis (ON) could improve visual outcome and reduce MRI disease activity 6 months after onset of ON.

METHODS

Sixty-eight patients with ON were randomized within 4 weeks from onset of symptoms. Thirty-four patients were randomized to IVIG 0.4 g/kg body wt, and 34 patients were randomized to placebo. Infusions were given at days 0, 1, 2, 30, and 60. Contrast sensitivity, visual acuity, and color vision were measured at baseline and after 1 week, 1 month, and 6 months. Pattern reversal visual evoked potential studies and gadolinium-enhanced MRI were performed at baseline and after 1 and 6 months. Clinical relapses during follow-up were recorded.

RESULTS

There was no difference in the primary outcome, contrast sensitivity after 6 months, between patients randomized to treatment with IVIG or placebo. In addition, there was no significant difference in the secondary outcome measures, improvement in the visual function measures and MRI, at any time during follow-up. At baseline, a significantly higher number of patients in the IVIG group had one or more enhancing lesions on MRI and IVIG-treated patients had a significantly higher number of enhancing lesions on MRI than patients treated with placebo. No difference was found in number of patients with one or more enhancing lesions or number of enhancing lesions in subsequent scans between treatment groups. Number of relapses was equal in the two treatment groups during follow-up.

CONCLUSIONS

There was no effect of IV immunoglobulin (IVIG) on long-term visual function following acute optic neuritis, nor was there an effect of IVIG treatment in reducing latency on visual evoked potentials and thus preserving function of axons of the optic nerve.