Top PDF Visual acuity and contrast sensitivity of adult zebrafish

Visual acuity and contrast sensitivity of adult zebrafish

Visual acuity and contrast sensitivity of adult zebrafish

As larval zebrafish absorb enough oxygen through their skin, they can be embedded in methylcellulose for VA measurements [3]. This approach is not feasible in adult zebrafish, which need a constant flow of oxyge- nated water irrigating their gills. Restricting body move- ments in the adult zebrafish was rather challenging, we did however solve this problem by designing a custom made flow through chamber. It was not necessary to fix- ate the body of the fish in our experiments, as the small chamber offered enough restriction to allow the observa- tion of eye movements. This is likely less incriminating to the fish. However, a fixation would still be possible with the provided set-up (for instance by clamping the body of the anesthetized fish between two pieces of sponge [4]) if necessary for certain experiments.
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Efficacy of perceptual vision therapy in enhancing visual acuity and contrast sensitivity function in adult hypermetropic anisometropic amblyopia

Efficacy of perceptual vision therapy in enhancing visual acuity and contrast sensitivity function in adult hypermetropic anisometropic amblyopia

At each session, an algorithm analyzed the subject’s responses and accordingly adjusted the level of visual dif- ficulty to the range most effective for further improvement. Between sessions, the progress of the subject was used as a baseline for the next session. Thus, for each subject, an individual training schedule was designed based on the initial state of visual performance, severity of dysfunction, and progress in the course of treatment. The treatment was applied in successive 30-minute sessions, administered three times a week, for a total of approximately 45 sessions. Visual acuity and contrast sensitivity were checked at 15-session intervals. The first sessions were performed at the clinic under supervision, with additional sessions performed at home. Each treatment station (home PC) was connected to the central database server via the Internet. After each train- ing session, the results were automatically sent to the server via the Internet. The algorithm, which was located in the central server, calculated specific patient results and sent these back to the specific station as a tailored training task. This unique mechanism enables complete and comprehensive control of each patient performance, including data on exact date and time of training, length of training, and quality of training in high resolution. After completing the 45 training sessions, the subjects were scheduled for an end-of-treatment examination, which included the same basic assessments as the baseline examination. In the study group, there were a total of four visits, ie, a baseline visit, a 15th session visit
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A study of effect on visual acuity and contrast sensitivity following Nd-YAG laser capsulotomy in patients with posterior capsular opacification

A study of effect on visual acuity and contrast sensitivity following Nd-YAG laser capsulotomy in patients with posterior capsular opacification

Improvement in visual acuity and contrast sensitivity are the main aims for successful YAG laser posterior capsulotomy. Previous reports have focused primarily on visual acuity improvement after Nd:YAG laser as the main outcome measure. But this is inadequate to assess visual function which necessitates evaluation of contrast sensitivity 57 . In our study,

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A comparison of contrast sensitivity in early mild and early intermediate age-related macular degeneration after adjusting for age and visual acuity

A comparison of contrast sensitivity in early mild and early intermediate age-related macular degeneration after adjusting for age and visual acuity

It should be noted that the prognostic value of visual acuity is better in AMD patients whose con- trast sensitivity is less affected or intact in compar- ison to other patients whose contrast sensitivity is worse (23). Moreover, for AMD patients treatments with vascular endothelial growth factor inhibitors, as well as both photodynamic therapy and laser pho- tocoagulation were found to be more effective only if contrast sensitivity is less affected (24). It should also be noted that early diagnosis of AMD can help prevent blindness in the future and functional acuity contrast sensitivity might be useful for early detec- tion of the age-related macular progress in the ab- sence of clinical changes in fundus when compared to previous fundus photography. Haegerstrom-Port- noy’s results demonstrate that low contrast vision functions can successfully predict subsequent loss of high contrast visual acuity (25).
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Effect of retinal laser photocoagulation on contrast sensitivity and visual acuity in patients of diabetic retinopathy

Effect of retinal laser photocoagulation on contrast sensitivity and visual acuity in patients of diabetic retinopathy

A study of health related quality of life (HRQoL) appraises contrast sensitivity (CS) as a newer measure of visual function and its value in determining HRQoL and health utility in comparison to the most standard measure, visual acuity. It shows that CS has significant and independent properties to visual acuity. 5 Visual function at low contrast is an essential part of visual capability which may change independently of visual function at high contrast and thus both the areas of function should be investigated. Neither visual acuity nor CS losses are specific findings; they rather depict loss of certain kind of visual information somewhere in its long optical and neural processing path. 6
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An Assessment of the Visual Acuity and Contrast Sensitivity of Commercial Vehicle Drivers in Rivers State, Nigeria

An Assessment of the Visual Acuity and Contrast Sensitivity of Commercial Vehicle Drivers in Rivers State, Nigeria

between contrast sensitivity deficits and crash risk observed by may reflect the increased representation of drivers with significant contrast sensitivity impairments. Contrast sensitivity measured under photopic conditions was a better predictor of the recognition of road signs, obstacles and pedestrians while driving at night than was photopic visual acuity 11 . A reduced contrast sensitivity can prevent an intoxicated driver from detecting obstacles in his field of view in some situations. A reduction in contrast sensitivity combined with changes in ocular- motor control and attention deficits may have a strong effect on performance while under the influence of alcohol 12 . In more unfavourable conditions, such as fog at night, alcohol can reduce the visibility of an object to the point of being below the threshold of detectability. Commercial vehicles between the ages of 20 and 50 are expected to have a log contrast sensitivity of 1.80 and above, and those below 20 years and above 50 years are expected to have a log contrast sensitivity of 1.65 and above.
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<p>Comparing Visual Acuity, Low Contrast Acuity and Contrast Sensitivity After Trifocal Toric and Extended Depth of Focus Toric Intraocular Lens Implantation</p>

<p>Comparing Visual Acuity, Low Contrast Acuity and Contrast Sensitivity After Trifocal Toric and Extended Depth of Focus Toric Intraocular Lens Implantation</p>

The AcrySof ® PanOptix ® IOL (Alcon Laboratories, Inc., Fort Worth, TX, USA) is a commonly used trifocal IOL and is the only trifocal IOL currently approved by the US FDA. It is actually a quadrafocal, but functionally uses 3 points of focus for clear vision at all ranges — near (40cm), intermediate (60cm), and distance. 2 It is designed as a diffractive aspheric optical and adds − 0.10 μ m of spherical aberration to compensate for the net positive spherical aberration from the cornea. 3 There is evidence to show that this IOL provides good vision across a range of distances. A recent study by Alfonso et al 4 found that 100% of patients had uncorrected visual acuities of 20/40 or better at 30cm, 40cm, 50cm, 60cm, 70cm, and distance 6 months postoperatively. Other studies have also shown that postoperative visual acuities at near, intermediate, and far with the PanOptix Trifocal IOL are good. 5–9 Despite the good visual acuity in these trifocal IOLs, visual dis- turbances can occur due to the light being split to create distinct focal points. Disturbances such as glare and halos are possible, and reduced contrast sensitivity has been reported relative to monofocal IOLs. 10,11
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Visual symptoms in Parkinson's disease

Visual symptoms in Parkinson's disease

Copyright © 2011 R. A. Armstrong. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Parkinson’s disease (PD) is a common disorder of middle-aged and elderly people in which degeneration of the extrapyramidal motor system causes significant movement problems. In some patients, however, there are additional disturbances in sensory systems including loss of the sense of smell and auditory and/or visual problems. This paper is a general overview of the visual problems likely to be encountered in PD. Changes in vision in PD may result from alterations in visual acuity, contrast sensitivity, colour discrimination, pupil reactivity, eye movements, motion perception, visual field sensitivity, and visual processing speeds. Slower visual processing speeds can also lead to a decline in visual perception especially for rapidly changing visual stimuli. In addition, there may be disturbances of visuospatial orientation, facial recognition problems, and chronic visual hallucinations. Some of the treatments used in PD may also have adverse ocular reactions. The pattern electroretinogram (PERG) is useful in evaluating retinal dopamine mechanisms and in monitoring dopamine therapies in PD. If visual problems are present, they can have an important effect on the quality of life of the patient, which can be improved by accurate diagnosis and where possible, correction of such defects.
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Evaluation of contrast sensitivity and other visual function outcomes in neovascular age-related macular degeneration patients after treatment switch to aflibercept from ranibizumab

Evaluation of contrast sensitivity and other visual function outcomes in neovascular age-related macular degeneration patients after treatment switch to aflibercept from ranibizumab

functioning following anti-VEGF treatment switch, this study was conducted to determine and evaluate change from base- line to week 12 in Pelli–Robson CS as the primary clinical end point in patients with recalcitrant exudative AMD, despite previous ranibizumab treatment who were switched to aflibercept therapy. Other outcome measures recorded and assessed were mean change in best corrected visual acuity (BCVA), mean change in central retinal thickness (CRT), and vision-related quality of life (or visual functioning) assessed using the National Eye Institute 25-Item Visual Function Questionnaire (NEI VFQ-25) single composite score. The latter captures key dimensions of self-reported vision-targeted health status and visual functioning in patients with chronic eye disease.
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Contrast Sensitivity Studies and Test- Review

Contrast Sensitivity Studies and Test- Review

Many conditions (age, myopia, etc.) and eye diseases (diabetes, cataract, glaucoma, etc.) affect CS, just before any change in V.A. is detected. Studies around the world have been conducted by various researchers on CS changes depending on the case and the effect this change has on patients’ daily lives. With age, the functions of the body begin to decline and so does CS. Although it has generally not been established by studies in patients with good visual acuity, what exactly neurological changes in age contribute to the loss of CS[22].The frequencies initially affected are the lowest and begin at approximately after the age of 40 [22]. Although myopia is a refractive error, it is a significant factor in effecting CS of the eye. Several studies show that there is a decrease in CSF in myopia, but the role of refractive error is unclear, as various optical factors, such as eye aberration (spherical aberration, diffusion by the crystalline lens), are inserted [23-25].The retina and the macula area are affected by several diseases, such as age-related macular degeneration, diabetes, detachment, central serous retinopathy, macular holes, etc. CS appears weakened to a degree regarding the severity of the disease [26-30]. For example, in the case of macular holes, the less tissue missing, the closer the CS is to the normal (but not completely normal) [30].Nevertheless, CS is definitely affected and usually before V.A. of the patient, in the early stages of the disease (age-related macular degeneration, diabetic retinopathy), causing problems in his quality of the patient life (driving, working etc.) [27,31,32]. In the retinal diseases category there are also studies with positive CS results. In some situation it is possible to recover part of the lost CS by restoring the tissue, such as retinal detachment, following surgery [28] or in cases of diabetic macular edema resection [6,32].
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Visual performance and aberration associated with contact lens wear in patients with keratoconus: a pilot study

Visual performance and aberration associated with contact lens wear in patients with keratoconus: a pilot study

Background: Rigid gas permeable (RGP) and silicone hydrogel (SH) contact lenses with specific designs are currently being used to improve visual function in patients with keratoconus. However, there are minimal data available comparing the effects of these lenses on visual func- tion in patients with keratoconus. The objectives of this study were to compare visual acuity and contrast sensitivity using spectacles, RGP lenses, and SH lenses, and to evaluate the effects of RGP and SH lenses on higher-order aberrations and visual quality in eyes with keratoconus. The relationship between visual outcomes, aberration, and visual quality were also examined. Methods: This was a pilot study involving 13 eyes from nine subjects with keratoconus. Subjects were fitted with RGP and SH contact lenses. Visual acuity and contrast sensitivity were measured using Snellen and Pelli-Robson charts, respectively. Ocular aberrations and visual quality were measured using an OPD-Scan II device. All measurements were conducted before and after contact lens wear.
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A prospective, randomized, fellow eye comparison of WaveLight<sup>&reg;</sup> Allegretto Wave<sup>&reg;</sup> Eye-Q versus VISX CustomVue&trade; STAR S4 IR&trade; in laser in situ keratomileusis (LASIK): analysis of visual outcomes and higher order aberra

A prospective, randomized, fellow eye comparison of WaveLight<sup>&reg;</sup> Allegretto Wave<sup>&reg;</sup> Eye-Q versus VISX CustomVue&trade; STAR S4 IR&trade; in laser in situ keratomileusis (LASIK): analysis of visual outcomes and higher order aberrations

Methods: In this randomized, prospective, single-masked, fellow eye study, LASIK was per- formed on 44 eyes (22 patients), with one eye randomized to WaveLight Allegretto, and the fellow eye receiving VISX CustomVue. Postoperative outcome measures at 3 months included uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), refrac- tive error, root-mean-square (RMS) value of total and grouped HOAs, contrast sensitivity, and Schirmers testing.

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A prospective, contralateral comparison of photorefractive keratectomy (PRK) versus thin-flap LASIK: assessment of visual function

A prospective, contralateral comparison of photorefractive keratectomy (PRK) versus thin-flap LASIK: assessment of visual function

with epithelial proliferation noted as filling the microstria and making them less apparent. Two eyes in the thin-flap LASIK group experienced flap tears intraoperatively – one resulting in mild flap edge scarring by 6 months that had no significant effect on visual function, and the other case affecting vision at 1 month postoperatively which was retreated with PRK at 3 months. As a result of the retreatment with the counter surgical technique, the ability to accurately compare visual acuity, contrast sensitivity, and HOAs between the 2 surgical methods was limited and both eyes from this patient were removed from analysis of these measures, but were still included in the analysis of complications.
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Evaluation of contrast visual acuity in patients with retinitis pigmentosa

Evaluation of contrast visual acuity in patients with retinitis pigmentosa

Although contrast sensitivity measurements have been recognized to be a more sensitive method for following patients with retinitis pigmentosa, there are several difficulties that need to be overcome for its routine use in the outpatient clinic. First, most of the contrast sensitivity measurements are performed with printed charts which are difficult to print with accurate contrast. Second, patients can remember the orientation of the gratings or the position of the letter on a printed chart. And third, accurate and consistent luminance changes are not fully achieved with slide projectors.
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Clinical Outcomes with a New Model of Extended Depth of Focus Intraocular Lens

Clinical Outcomes with a New Model of Extended Depth of Focus Intraocular Lens

All patients underwent a comprehensive preoperative ophthalmological exami- nation including measurement of uncorrected and corrected distance visual acu- ity (UDVA and CDVA), keratometry, optical biometry (IOLMaster, Carl Zeiss Meditec AG, Germany), manifest refraction, biomicroscopy, Goldmann appla- nation tonometry, and dilated fundoscopy. Postoperatively, patients were eva- luated the day after surgery, and at 1 week and 1 month after surgery. At these two postoperative visits, the following clinical tests were performed: measure- ment of monocular UDVA and CDVA, measurement of monocular dis- tance-corrected near (DCNVA, 40 cm) and intermediate visual acuity (DCIVA) (80 cm), and manifest refraction. Likewise, at 1 month postoperatively, a mono- cular distance-corrected defocus curve was obtained in all cases, including levels of defocus from +2 to −4 D in steps of 0.50 D as well as a measurement of bino- cular contrast sensitivity under mesopic conditions with Functional Acuity Contrast Test charts (CST 1800 system, Vision Science Research). Patient satis- faction and quality of life were determined by means of a questionnaire, which was completed by the patients at the last follow-up visit. Questions included sa- tisfaction about: adaption between photopic and mesopic conditions, ability to find the correct distance, night driving, vision during the day, halos, adaption between far and near vision and vice versa, as well as general satisfaction for dis- tance, intermediate and near vision, and overall satisfaction. Patients were also asked whether they would perform the same surgery again and whether they need to wear glasses for the daily tasks. Each subscale score was converted to a score between 0 and 5, with higher scores indicating better results. Finally, ha- lometry was also measured at this visit.
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Evaluation of contrast sensitivity and other visual function outcomes in diabetic macular edema patients following treatment switch to aflibercept from ranibizumab

Evaluation of contrast sensitivity and other visual function outcomes in diabetic macular edema patients following treatment switch to aflibercept from ranibizumab

Purpose: This study aims to investigate changes in contrast sensitivity (CS), visual acuity (VA), central retinal thickness (CRT), and vision-related quality of life in subjects with recalcitrant diabetic macular edema switched from long-term ranibizumab treatment to aflibercept. Patients and methods: In this prospective, investigator-masked, single-center study, 40 patients with persistent fluid, despite previous ranibizumab treatment, were switched to aflibercept with 5 consecutive monthly doses. The primary outcome was mean change from baseline to week 20 in Pelli–Robson CS. Secondary outcomes were mean change from baseline in best-corrected VA (BCVA), CRT, and National Eye Institute 25-Item Visual Function Questionnaire score.
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Improving the detection of correctable low vision in older people

Improving the detection of correctable low vision in older people

measurements in their studies (Strahlman et al., 1990a;van der Pols et al., 2000a), and it is thought that if one test of visual function is to be assessed in screening programmes, then the best single test is likely to be visual acuity. This chapter attempts to broaden this discussion by reviewing whether a battery of vision tests might provide a more complete assessment of visual function in older people and might be better related to the consequences of a range of visual problems in terms of adverse effects on daily living. For example, most definitions of blindness and some definitions of low vision (visual impairment) include criteria for visual field loss as well as visual acuity loss. In addition, standard visual acuity charts have high contrast optotypes, yet most visual objects in the real world are of lower contrast. Many visual problems affecting older people have a greater effect on low contrast resolution than high contrast resolution, and many authors have therefore highlighted the potential of contrast sensitivity for vision screening (Brabyn et al., 2001f;Brabyn et al., 2001e;Lord & Dayhew, 2001). Another factor that has often been ignored is the issue of binocularity. Stereopsis has been described as the “barometer of binocularity” (Saladin, 2005) and may play an important role in preventing falls (Evans & Rowlands, 2004n).
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Visual Functions after Laser Photocoagulation in Central Serous Chorioretinopathy

Visual Functions after Laser Photocoagulation in Central Serous Chorioretinopathy

Many authors describe diminished contrast sensitivity (CS), colour discrimination and focal or multifocal electro- retinography (mfERG) in acute idiopathic CSC not only when best corrected visual acuity (BCVA) decreases, but also when it remains satisfactory (1, 2, 5, 10, 14, 21, 25, 35). Some studies refer co-existing alteration of the retinal func- tion within the central 40° area on the fellow, unaffected eye of the patients (10, 21). Others observe that its ab- normalities extend beyond the clinically observed fundus changes mainly in clinically affected eyes (26) or, only in af- fected eyes limited to the pathological retinal region (35). The persistence of colour vision defects, decreased CS, de- creased central retinal sensitivity on microperimetry and subnormal or low-normal signals from central retinal re- gion by means of mfERG was described also after spontane- ous resolution of unilateral CSC either only on the affected eyes (28, 33), or also in clinically uninvolved, fellow eyes of patients (2, 10, 13, 19, 20, 31). Changes in the foveal pho-
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Visual function assessment in medical imaging research

Visual function assessment in medical imaging research

An observer’s ability to process visual information is one of the fundamental links in the diagnostic imaging chain. 12 Visual function is the primary tool through which imaging information is gathered for processing into concrete data. Decreased visual acuity could significantly increase the threshold contrast required to identify high-frequency diagnostic information. 13 Contrast sensitivity is an indicator of visual pattern-detection for stimuli of various sizes. Low-contrast objects are difficult to evaluate and are one of the greatest challenges for observers reviewing images. 1 Contrast sensitivity across all spatial frequencies declines with age. This decline
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Attitudes among older drivers towards medical assessment at renewal of driving license in Sweden

Attitudes among older drivers towards medical assessment at renewal of driving license in Sweden

A current debate in Sweden endorsed by the Swedish Transport Agency concerns whether periodic medical testing should be implemented for people starting at age 65 or 70 years to check their fitness to drive. There are many argu- ments in favour as well as some against this proposal. In some countries or states where medical and cognitive screening for older drivers has been introduced, there is a little evidence that such screening helps reduce injuries and fatalities on the road for this group [12, 13]. Some studies have demonstrated a reverse effect in which more injuries occur among older drivers in countries or states where there is screening testing [14]. This finding is interesting, because the prevalence of some declines (i.e. contrast sensitivity and glare sensitivity) that are excluded from driving capability standards is higher than others that are included (i.e. visual acuity and visual field) [15]. declines not being included in standards for driving ca- pability, contrast sensitivity and glare sensitivity, has been shown higher than others being included (visual acuity and visual field) Many countries require vision tests for older drivers at driver’s license renewal, but fail to implement val- idated vision tests that can predict driving performance or to present the effects of these tests in terms of decreased acci- dents [16]. Thorslund and Strand suggest that available and broadly used tests of visual acuity should be combined with
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