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Background Engagement in cognitively stimulating activities is associated with decreased rates of cognitive decline in older adults. However, most cognitively stimulating tasks require good vision, potentially affecting the ability of visually impaired adults to engage in these activities. We examined the relationship between vision and participation in cognitively stimulating activities. Method Data from the Health, Aging, and Body Composition study (1999–2005) were analyzed. Associations between visual function (visual acuity [VA], contrast sensitivity [CS], and stereo acuity [SA] impairments) and annual rates of change in number of cognitively stimulating activities (by self-report) performed at least once a month were examined. Results Analyses included 924 participants aged 75.2 ± 2.8 years. At baseline, impaired CS (27%) and SA (29%) were associated with participation in fewer cognitive activities (β = −0.33, 95% CI = −0.63, −0.03 and β = −0.32, 95% CI = −0.61, −0.03, respectively), while VA (8%) was not (β = −0.34, 95% CI = −0.81, 0.13). In longitudinal models, groups with and without VA, CS, and SA impairments exhibited declines in monthly cognitive activities over time. Annual rates of decline were relatively higher in the VA (β = −0.16, 95% CI = −0.26, −0.05) and CS (β = −0.14, 95% CI = −0.19, −0.09) impaired groups than observed in the respective unimpaired groups (no VA: β = −0.12, 95% CI = −0.15, −0.10; no CS: β = −0.12, 95% CI = −0.15, −0.09), but did not achieve statistical significance. Stereo acuity (β = −0.13, 95% CI = −0.17, −0.09) and no SA (β = −0.13, 95% CI = −0.16, −0.10) groups had similar rates of decline. Conclusions Visually impaired older adults participate in fewer cognitive activities and although participation decline is similar to the non-impaired, lower overall participation indicates a need to identify cognitively stimulating activities accessible to visually impaired older adults.

Background: Preschool vision screenings are considered to be cost-effective methods to identify children with vision disorders. The children of this age group are poor at communicating their symptoms and hence screening is mandated. This study is aimed at estimating the diagnostic accuracy and agreement of Lea, HOTV and E visual acuity charts for detecting significant refractive errors. Methods: A cross-sectional study was conducted, in which monocular unaided vision assessment of each study participant was performed with Lea, HOTV and E charts. Stereo acuity was measured with the Randot Preschool Test and a comprehensive eye examination including dilatation was performed. Significant refractive error was defined as hyperopia > 3.25 D, myopia > 2.00 D, astigmatism > 1.50 D, anisometropia if interocular difference > 1.00 D for hyperopia, > 3.00 D for myopia or > 1.50 D for astigmatism. Sensitivity, specificity, positive and negative predictive values were estimated. Bland–Altmann plots were generated to help identify the level of agreement between the vision charts. Results: A total of 256 eyes were analysed. Lea, HOTV and E had sensitivities of 87.8 per cent, 90.2 per cent and 90.2 per cent, respectively. Specificity and positive predictive values were better for HOTV (77.3 per cent, 65.5 per cent) and Lea (75 per cent, 62.6 per cent), compared to E chart (69.8 per cent, 58.7 per cent). Negative predictive values for Lea, HOTV and E charts were 92.8 per cent, 93.8 per cent and 93.8 per cent, respectively. Bland– Altmann analysis showed good agreement between Lea and HOTV, Lea and E, and HOTV and E visual acuity charts. The acuity difference was least between Lea and HOTV charts (0.1 logMAR). Eighty-five (33.2 per cent) eyes had significant refractive errors. Eighty (94.1 per cent) eyes were astigmatic. Conclusion: The diagnostic accuracy of the visual acuity charts was high for the identification of significant refractive errors in preschool children. There was very good agreement between the visual acuity charts.

Technological advancements in virtual reality challenge the human vision, especially stereopsis, a function, which characterizes how two eyes coordinate to form a unified three-dimensional (3D) representation of the external world and is found to be deficient in 30% of the normal population. Although a few previous studies have consistently found that the perceptual learning of stereopsis significantly improved stereoacuity, an underlying mechanism of stereo learning remains heavily debated. Here, we trained subjects with normal stereo vision (assessed with the FLY Stereo Acuity Test) to judge stereopsis containing three types of binocular disparity orders (i.e., zero-, first-, and second-order), aiming to systematically examine the characteristics and plasticity of stereo learning. Thirty subjects were randomly assigned to the three training groups (each for the zero-, first-, or second-order disparity separately). The disparity thresholds were measured before and after training. The disparity threshold was measured in 10 additional control subjects only at the pre- and post-training phase. Stereoscopic images were displayed through a shutter goggle, which is synchronized to a monitor. We found that the training significantly improved the zero-, first-, and second-order disparity threshold by 52.42, 36.28, and 14.9% in the zero-order training condition; 30.44, 63.74, and 21.07% in the first-order training condition; and 30.77, 25.19, and 75.12% in the second-order training condition, respectively. There was no significant improvement in the control group. Interestingly, the greatest improvements in the first- and second-order disparity threshold were found in the corresponding disparity training group; on the contrary, the improvements in the zero-order disparity threshold were comparable across all the three disparity training groups. Our findings demonstrated both general (related to the zero-order disparity) and specific improvements (related to the first- and second-order disparity) in stereo learning, suggesting that stereo training occurs at different visual processing stages and its effects might depend on the specific training sites.

Stereovision is the ability to perceive fine depth variations from small differences in the two eyes' images. Using adaptive optics, we show that even minute optical aberrations that are not clinically correctable, and go unnoticed in everyday vision, can affect stereo acuity. Hence, the human binocular system is capable of using fine details that are not experienced in everyday vision. Interestingly, stereo acuity varied considerably across individuals even when they were provided identical perfect optics. We also found that individuals' stereo acuity is better when viewing with their habitual optics rather than someone else's (better) optics. Together, these findings suggest that the visual system compensates for habitual optical aberrations through neural adaptation and thereby optimizes stereovision uniquely for each individual. Thus, stereovision is limited by small optical aberrations and by neural adaptation to one's own optics.

A pilot’s Helmet-Mounted Display (HMD) is now a critical part of the aircraft system. Next generation HMDs will be able to display information and imagery binocularly, with stereoscopic depth. Stereo 3D (S3D) can potentially be used to enhance situational awareness and improve performance. The degree to which performance is improved may be linked to individual visual capabilities of the user, in particular, stereo acuity. Stereo acuity varies tremendously in the general population with up to 30% being classed as ‘stereo blind’. For most military aviators there is a minimum stereo acuity standard, however current test methods are crude and fallible. Many previous S3D studies do not accurately characterize individual stereo acuity, and in some cases do not even screen for its presence, making their results difficult to interpret. The Operational Based Vision Assessment (OBVA) laboratory has developed a flight simulation platform using an SA Photonics SA-62 HMD to display stereoscopic symbology and five 85-inch displays to provide the “out the window” view. After completing a battery of vision tests, participants fly various mission profiles while responding to a combination of navigational instructions and warning alerts displayed in the HMD. The warning alerts are displayed in 2D (flashing at 1 Hz), intermittent S3D (flashing on and off at depth), persistent S3D (alternating between 2 depth planes), and dynamic S3D (motion in depth). We present preliminary data examining whether a stereoscopic HMD could be used to improve performance when responding to a critical warning alert, and discuss potential implications for military aviator vision standards as well as HMD requirements

Background The peak sports performance of elite athletes is the result of talent and longterm, systematic training. Only minor differences among athletes determine the results in sport today. In selected sports events, stereoscopic vision has a fundamental influence on the executed sports performance. Methods The quality of stereopsis was determined in 2 groups of top-level athletes at the age of 16-18 years (21 pole vaulters and high jumpers and 25 swimmers) and in a control group of 25 nonathletes in the same age category. Two measured parameters (results and time in the stereopsis test) were compared among the studied groups. To determine the quality of stereopsis, the "Fly-S Stereo Acuity Test with LEA Symbols" field stereoacuity test was used. Results The average level of stereopsis in the pole vaulters and high jumpers reached the value of 9.9 (max. 10), and the average time needed for performing the stereopsis test was 11.6 seconds. The group of swimmers and control group showed worse results in both measured parameters (the average level of stereopsis: 9.4, resp. 9.1, the average test time: 30.0 seconds, resp. 36.1 seconds). A significant difference between the group of pole vaulters and high jumpers and swimmers was confirmed in both monitored parameters. No significant differences were found between the group of swimmers and nonathletes. Conclusions On the basis of the stereopsis test results we can say that top-level pole vaulters and high jumpers have a high quality of stereopsis and very fast identification and decisionmaking abilities in spatial orientation.

Purpose Visual acuity (VA) of the amblyopic eye is usually considered for monitoring improvement with therapy. However, participation of the amblyopic eye under binocular viewing conditions is also important. This study investigated the use of a clinically available tool VTS4 (Vision Therapy System 4) to quantify the participation or suppression of the amblyopic eye under binocular viewing conditions. Methods A cross-sectional study on patients with anisometropic amblyopia was undertaken. Monocular VA was thresholded. Stereo acuity was measured with Randot stereo test. Simultaneous macular perception (SMP) targets in VTS4 were dichoptically presented. SMP target size was reduced till the amblyopic eye's target disappeared (suppression scotoma size). An average of three measurements was taken for the suppression scotoma size. Results Twenty-eight patients participated (aged 6 to 21 years). The mean interocular VA difference was 0.50 ± 0.27 logMAR. The mean scotoma size was 8.2° ± 5.4°. Mean stereo acuity was 2.06 ± 0.34 log arc seconds from 21 patients on whom stereopsis could be measured. Suppression scotoma size showed a significant (P < 0.001) positive correlation with both interocular VA difference (r = 0.59) and stereoacuity (r = 0.72). Conclusions Participation of the amblyopic eye under binocular viewing condition can be assessed by measuring the suppression scotoma size in VTS4, even when stereoacuity is poor or not measurable. Smaller the suppression scotoma, better is the amblyopic eye's participation. Translational Relevance VTS4 can be used in monitoring amblyopia therapy by quantifying suppression of the amblyopic eye.

Purpose The effect of contrast‐balanced dichoptic video game training on distance visual acuity (DVA) and stereo acuity has been investigated in severe‐to‐moderate amblyopia, but its effect on mild amblyopia and fixation stability has not been assessed. This pilot study aimed to evaluate the effect of home‐based dichoptic video game on amblyopic eye DVA, stereo acuity and fixation stability in adults with mild amblyopia. Methods A randomized single‐masked design was adopted. The active 6‐week home‐based treatment was an anaglyphic, contrast‐balanced dichoptic video game, and the placebo was an identical non‐dichoptic game. Participants (n = 23) had mild amblyopia (amblyopic DVA ≤ 0.28 log Minimum Angle of Resolution (logMAR)). The primary outcome was change in amblyopic DVA at 6 weeks postrandomization. Near visual acuity, stereo acuity and fixation stability (bivariate contour eclipse area) were also measured. Follow‐up occurred at 12 and 24 weeks postrandomization. Results Mean amblyopic eye DVA was 0.21 ± 0.06 and 0.18 ± 0.06 logMAR for the active (n = 12) and placebo (n = 11) group, respectively. Amblyopic DVA improved significantly more in the active group (0.09 ± 0.05) than in the placebo group (0.03 ± 0.04 logMAR; p

Visual standards for military aviators were historically set in the 1920s with requirements based on the visual systems of aircraft at the time, and these standards have changed very little despite significant advances in aircraft technology. Helmet-mounted displays (HMDs) today enable pilots to keep their head out of the cockpit while flying and can be monocular, biocular or binocular in design. With next generation binocular HMDs, flight data can be displayed in three-dimensional stereo to declutter information presented, improving search times and potentially improve overall performance further. However, these new visually demanding technologies place previously unconsidered stresses on the human visual system. As such, new medical vision standards may be required for military aircrew along with improved testing methods to accurately characterise stereo acuity.

Background: In recent years, it has been established that the suppression of the amblyopic eye by the fellow eye is the major cause of amblyopia. New behavioural therapies like dichoptic therapy attempt to reduce suppression in amblyopic adults who have passed the critical stage of visual cortex development. Anisometropic amblyopia has the highest prevalence of amblyopia, and managing this condition in adults may lead to improvement in the quality of life. Aim: The purpose of the review is to assess the impact of this novel treatment of amblyopia, with particular focus on using dichoptic therapy for anisometropic amblyopia in adults. Methods: A literature search was conducted on articles published in the last 20 years, and papers were sourced from databases such as Elsevier, Science Direct and PubMed using the reference manager Mendeley. (The search was performed from December 2017 to December 2018.) Results: Evidence from located studies in adults with anisometropic or mixed amblyopia managed with new behavioural treatments including dichoptic therapy showed some significant improvement in the best-corrected distance visual acuity, stereopsis and contrast sensitivity whilst improving or restoring optimal binocular vision. Conclusion: Adults with anisometropic and/or mixed amblyopia can benefit from dichoptic therapy with a unique approach to improve binocularity concurrently. The therapy represents a viable option for managing amblyopia in adults and can be administered as office-based or home-based treatment in a timely manner that could improve the quality of life for such patients.

Purpose: To investigate stereo acuity of professional athletes in an open (baseball) and closed (golf) skilled sport compared to nonathletes using a new digitized version of the Titmus Stereo Test/Wirt Circles. Additionally, to examine the new test for reliability and validity. Methods: Participants included professional baseball players (PBP; n = 265) and professional women golfers (LPGA; n = 52), and nonathletes (n = 107). All participants were tested on the RightEye Fine Depth Perception (FDP) test and a subset (n = 20) was retested to determine reliability and internal consistency. A different subset (n = 81) was tested for validity comparing the Titmus Stereo Test/Wirt Circles to the RightEye FDP test. Cronbach’s Alpha, intraclass correlation coefficients (ICC) were examined for reliability and ANOVA was conducted to determine convergent validity as well as differences in stereo acuity between groups. Results: Results: The test was revealed to have high reliability and validity, therefore being a good measure of stereo acuity. Furthermore, significant differences (p

At the start of the 20th century, Moritz von Rohr invented the synopter: a device that removes 3D depth cues that arise from binocular disparities and vergence. In the absence of these visual cues, the observer is less aware of the physical flatness of the picture. This results in a surprisingly increased depth impression of pictorial space, historically known as the ‘plastic effect’. In this paper we present a practical design to produce a synopter and explore which elements of a painting influence the plastic effect. In the first experiment we showed 22 different paintings to a total of 35 observers, and found that they rate the synoptic effect rather consistent over the various paintings. Subsequent analyses indicated that at least three pictorial cues were relevant for the synoptic effect: figure–ground contrast, compositional depth and shadows. In experiment 2, we used manipulated pictures where we tried to strengthen or weaken these cues. In all three cases we found at least one effect that confirmed our hypothesis. We also found substantial individual differences: some observers experience little effect, while others are very surprised by the effect. A stereo acuity test revealed that these differences could not be attributed to how well disparities are detected. Lastly, we informally tested our newly designed synopter in museums and found similar idiosyncratic appraisal. But the device also turned out to facilitate discussions among visitors.

Background: The purpose of having a naked eye 3D glasses-free smartphone is to achieve 3D effects without the need for glasses. The purpose of this study was to evaluate whether this technology could be utilized to measure stereoacuity. Methods: A 2K auto-stereoscopic smartphone was used to imitate the quantitative section of Random Dot Stereo Acuity Test (contour based symbol) and Random Dot 3 Stereo Acuity Test (random dot based symbol) to measure the stereopsis of subjects. Results: There was a high level of agreement between the two methods using Bland-Altman statistical analysis ( vs . Random Dot Stereo Acuity Test, 95% limits of agreement ±1.29 arcseconds; vs . Random Dot 3 Stereo Acuity Test, 95% limits of the agreement also ±1.29 arcseconds). Conclusions: The auto-stereoscopic smartphone is a useful tool to evaluate stereopsis.

Background. The advantage of using an autostereoscopic smartphone is that it can achieve 3D effects without the need for glasses. The purpose of this study was to evaluate whether this technology could be utilized to detect stereoacuity. Methods. An autostereoscopic smartphone was used to imitate Lang stereotest I & II, Pass Test 3, Dinosaur Stereoacuity Test, and the Random Dot Stereo Acuity Test to screen the stereopsis of children from 3–6 years old. Results. No significant difference was found between each pair of groups (autostereoscopic smartphone vs. Lang stereotest I, Lang stereotest II, Pass Test 3, Dinosaur Stereoacuity Test, and Random Dot Stereo Acuity Test, respectively; Wilcoxon signed-rank test, P value all >0.05). All of the weighted kappa were higher than 0.84. Therefore, all of the comparisons between measurements showed a high level of agreement. Conclusions. The autostereoscopic smartphone is an effective tool when used for the screening of deficiency in stereopsis.

BACKGROUND: The preschool children hardly complain about their vision problems. It is of paramount importance to screen them with an objective tool and compare with the gold standard technique. AIM: To compare the values obtained with Plusoptix A09 and cycloplegic refraction in 3–6 years children and agreement to detect refractive amblyogenic risk factors. SUBJECTS AND METHODS: A cross-sectional study was conducted in the Outpatient Department of Ophthalmology in a tertiary care hospital. Informed consent from parents and verbal assent from children were obtained. Each subject had monocular vision assessment with Lea symbol chart, stereo acuity measurement with Frisby, refractive screening with Plusoptix A09, squint assessment, and anterior segment evaluation before administering Homatropine hydrobromide (homide) 2% eye drops. Cycloplegic refraction and posterior segment evaluation were performed for final diagnosis. STATISTICAL ANALYSIS: Descriptive statistics were used to summarize the data. Spearman correlation coefficient and kappa statistics were also employed. RESULTS: In total, data of 94 children were analyzed. The correlation values obtained between plusoptix and cyclorefraction values for spherical, cylindrical, spherical equivalent were 0.508 (P < 0.0001), 0.779 (P < 0.0001), and 0.407 (P < 0.0001), respectively. Refractive errors were seen in 32% and amblyopia in 17% of eyes. Kappa value was κ = 0.974 in detecting refractive amblyogenic risk factors. CONCLUSION: Good correlation was found between the plusoptix and cyclorefraction values. Cylindrical values showed a better correlation. Refractive errors and amblyopia were the major ocular disorders observed. There was significant agreement between the refractive techniques in detecting amblyogenic risk factors.

In the presented experiment we have investigated the effects of hypnosis on the visual perception. In particular we have devised three tests to check the perception of luminance dynamic range, stereo acuity and color preference on the basic color set of Luscher test. Results have proven no effect on stereo acuity but significant effects on the perception of luminance dynamic range and color preference. The perception of luminance dynamic range increase under hypnosis and the color preferences are largely modified. Nella sperimentazione qui presentata sono stati indagati gli effetti dell’induzione ipnotica sulla percezione visiva. Nello specifico tre diversi esperimenti hanno testato l’effetto della trance ipnotica sulla percezione della dinamica di luminosita, sulla visione stereoscopica e sulla scelta del set base dei colori del test di Luscher. I test hanno evidenziato un ampliamento significativo della dinamica percepita ed un cambiamento importante nella scelta dei colori, mentre non vi sono state modifiche significative nella percezione stereoscopica.

Purpose: This study investigated differences in stereoscopic fusional area between those with good and poor stereoacuity in viewing stereoscopic displays. Methods: Stereo acuity of 39 participants (18 males and 21 females, 23.6±3.15years) was measured with the random dot stereo butterfly method. Participants with stereo-blindness were not included.Stereoscopic fusional area was measured using stereoscopic stimulus by varying the amount of horizontal disparity in astereoscopic 3D TV. Participants were divided into two groups of good and poor stereo acuity. Criterion for good stereoacuity was determined as less than 60 arc seconds. Measurements arising from the participants were statisticallyanalyzed. Results: 26 participants were measured to have good stereo acuity and 13 participants poor stereo acuity. Incase of the stereoscopic stimulus farther than the fixation point, threshold of horizontal disparity for those with poorstereo acuity were measured to be smaller than the threshold for those with good stereo acuity, with a statisticallysignificant difference. On the other hand, there was no statistically significant difference between the two groups, in caseof the stereoscopic stimulus nearer to the fixation point. Conclusions: In viewing stereoscopic displays, the boundary ofstereoscopic fusional area for the poor stereo acuity group was smaller than the boundary of good stereo acuity grouponly for the range behind the display. Hence, in viewing stereoscopic displays, participants with poor stereo acuity wouldhave more difficulty perceiving the fused image at farther distances compared to participants with good stereo acuity.Key words: Stereo acuity, Stereoscopic fusional area, Stereoscopic display

Purpose- The aim of the study is to compare visual functions of children with uncorrected amblyopia treated with different binocular I Pad games and/or patching. Methods- Children with untreated amblyopia were enrolled in this pilot study. Children were divided into three groups: children treated with patching only, children attributed to play binocular snake I Pad game with patching, children attributed to play binocular blocks I Pad game with patching. Visual acuity VA, refraction, stereo acuity test, and ocular alignment tests were performed for all participants in the first visit and 4 weeks after starting treatment. Visual functions were compared between both visits. Results- A total of 18 children with untreated amblyopia participated in this study. Children were divided into three groups: Group 1= 8 children treated with patching only, Group 2= 5 children attributed to play binocular snake I Pad game with patching, and Group 3= 5 children attributed to play binocular blocks I Pad game with patching. There was no significant difference (P > 0.05) in gender and age between the three groups. Children showed good compliance to all patching treatment and I pad games groups. After 4 weeks, Visual acuity was improved in all amblyopic children in the form of one line improvement in patching group, two lines with binocular snake I Pad game and three lines with binocular blocks I Pad game. Moreover, stereoacuity was improved in all groups with greatest advance in blocks games group followed by snake group then patching group. Conclusion- This study demonstrated great effectiveness of both snake, and blocks binocular I Pad games on visual functions improvement for treatment of amblyopia. These games can contribute with patching in achieving better VA and stereoacuity enhancement in a shorter duration than patching alone.

The gold-standard treatment for childhood amblyopia remains patching or penalizing the fellow eye, resulting in an average of about a one line (0.1 logMAR) improvement in visual acuity following ≈ 120 hours of patching (Stewart et al., 2004, 2007) in children 3 to 8 years old. However, compliance with patching and other treatment options is often poor. In contrast, fast-paced action video games can be highly engaging, and have been shown to yield broad-based improvements in vision and attention in adult amblyopia. Here, we pilot tested a custom-made action video game to treat children with amblyopia. Twenty-one (n=21) children (mean age 9.95 ± 3.14 [se]) with unilateral amblyopia (n=12 anisometropic and n=9 strabismic) completed 20 hours of game play either monocularly, with the fellow eye patched (n=11), or dichoptically, with reduced contrast to the fellow eye (n=10). Participants were assessed for visual acuity (VA), stereo acuity and reading speed at baseline, and following 10 and 20 hours of play. Additional exploratory analyses examined improvements after 6–10 weeks of completion of training (follow-up). Following 20 hours of training, VA improved on average by 0.14 logMAR (≈ 38%) for the dichoptic group and by 0.06 logMAR (≈ 15%) for the monocular group. Similarly, stereoacuity improved by 0.07 log arcsec (≈ 17%) following dichoptic training, and by 0.06 log arcsec (≈ 15%) following monocular training. Across both treatment groups, 7 of the 12 individuals with anisometropic amblyopia showed improvement in stereoacuity, while only 1 of the 9 strabismic individuals improved. Most improvements were largely retained at follow-up. Our feasibility study suggests that the action videogame approach may be used as an effective adjunct treatment for amblyopia in children, achieving results similar to those of the gold-standard treatment in shorter duration.

Many studies tried to develop a 3D display based stereo test as a substitute for the conventional stereo test. Although many 3D monitor based stereo tests have various advantages over the conventional stereo tests with printed stimuli, they have a crucial limitation in manipulating disparity. The least value for disparity manipulation is one pixel, which is too big to screen the normal stereo acuity in pc environment with a short viewing distance. In this explorative study, a Gabor image was employed as a test stimulus, because its position can be manipulated by changing its phase information, which allows sub-pixel manipulation for disparity. Instead of employing the methods of the conventional stereo tests where measurement was made only once for each of a wide range of disparity values, 10 replications were administrated for each of 6 disparity levels. The results from the test using Gabor images were compared with those using random dot stimulus because the latter stimulus was exactly the same as that of the conventional stereo test. The correlation coefficient between two tests was found to be moderate. After one month later, the whole test was repeated in the same settings. The correlation coefficient between test and retest results from Gabor images was found to be as high as that from a random dot stimulus, implying high test-retest reliability. These results suggest that a Gabor stimulus could be used as a test stimulus for the valid and reliable stereo test, even in the limited condition, such as 3D environment with a short viewing distance and a condition for evaluating the stereo acuity very precisely.

As part of a genome-wide association study (GWAS) of perceptual traits in healthy adults, we measured stereo acuity, the duration of alternative percepts in binocular rivalry and the extent of dichoptic masking in 1060 participants. We present the distributions of the measures, the correlations between measures, and their relationships to other psychophysical traits. We report sex differences, and correlations with age, interpupillary distance, eye dominance, phorias, visual acuity and personality. The GWAS, using data from 988 participants, yielded one genetic association that passed a permutation test for significance: The variant rs1022907 in the gene VTI1A was associated with self-reported ability to see autostereograms. We list a number of other suggestive genetic associations (p

Purpose To evaluate the feasibility of the TNO chart for the assessment of distance stereo acuity using an inverted telescope in normal subjects Methods Stereoacuity of emmetropic adult subjects was measured for near The distance stereoacuity was measured using the TNO chart held at cm and an inverted telescope Galilean design mm X Camma Inc China in front of the examinee rsquo s eyes Results The near stereopsis ranged from quot seconds of arc quot Median quot Distance stereopsis ranged from quot quot Distance stereoacuity could be measured in subjects Conclusion It is possible to measure the distance with an inverted telescope and a TNO chart Further improvisation is required to design an optimal telescope system with larger field gradable zoom and measurable inter pupillary distance

Purpose Evidence from animals and blind humans suggests that early visual experience influences the developmental calibration of auditory localization. Hypothesizing that unilateral amblyopia may involve cross-modal deficits in spatial hearing, we measured the precision and accuracy of sound localization in humans with amblyopia. Methods All participants passed a standard hearing test. Experiment 1 measured sound localization precision for click stimuli in 10 adults with amblyopia and 10 controls using a minimum audible angle (MAA) task. Experiment 2 measured sound localization error (i.e., accuracy) for click train stimuli in 14 adults with amblyopia and 16 controls using an absolute sound localization task. Results In Experiment 1, the MAA (mean ± SEM) was significantly greater in the amblyopia group compared with controls (2.75 ± 0.30° vs. 1.69 ± 0.09°, P = 0.006). In Experiment 2, the overall sound localization error was significantly greater in the amblyopia group compared with controls (P = 0.047). The amblyopia group also showed significantly greater sound localization error in the auditory hemispace ipsilateral to the amblyopic eye (P = 0.036). At a location within this auditory hemispace, the magnitude of sound localization error correlated significantly with deficits in stereo acuity (P = 0.036). Conclusions The precision and accuracy of sound localization are impaired in unilateral amblyopia. The asymmetric pattern of sound localization error suggests that amblyopic vision may interfere with the development of spatial hearing via the retinocollicular pathway.

Background and Aims: Watching 3D images are known to induce more ocular, systemic fatigue and discomfort, which can be referred to as '3D asthenopia', than watching two-dimensional (2D) images. This study was designed to determine the stereo acuity levels among college students and compare it with the hours of use of digital technology. Methods: University students in the age group of 18-25 years were screened for visual acuity for distance and near. Refraction was done to find the presence of refractive errors. Those students who had no vergence or accommodation dysfunction and orthophoria were only included in the study. Stereopsis was assessed using random dot stereo acuity chart. The stereo acuity results were grouped as either normal (20 arc seconds or better), Borderline (25 arc seconds to 40 arc seconds) and reduced stereopsis (50 arc seconds to 400 arc seconds). Students were also questioned about the hours of use of digital media. Results: The average age of the 246 participates was 20 ± 1.9 years with 78 (32%) were males and 168 (68%) were females. 7% of the population was found to be myopic in our study. The hours of use of digital technology ranged from 0-9 hours a day. Only 13.1% of the student's population met the normal level of stereopsis (20 arc seconds). Around 44.3% of the study population was found to have borderline stereopsis. Also 42.6% of the study population, reduced stereopsis was found. Among the reduced stereo acuity levels, we found stereoacuity levels as low as 100-200 arc seconds were found in nearly 17.6% of the study population. Conclusion: It is very much evident from this study that a large group of college students are not enjoying the highest level of binocular vision, which in turn can have a negative impact on their academic performance.

Nowadays there is a wide variety of Virtual Reality (VR) applications for users of all age groups. An essential part of most VR systems is stereoscopy. From perceptual research, it is known that stereoscopic perception deteriorates with age [Garnham and Sloper 2006]. As indicator for stereoscopic perception, the authors of this and further studies used stereo acuity, i.e. the smallest disparity difference detected by the visual system. Norman et al. [2000] showed that the declined stereo acuity in older humans can cause these users to perceive less depth in random-dot stereograms. Since VR applications for rehabilitation are advancing, one can expect increasing numbers of elderly users. However, up to now it is unclear whether the age-specific changes in stereoscopic perception might impair the use of VR applications for older people. In our study, we presented stereoscopically rendered virtual objects. The primary aim of this study was to examine possible age differences in fusion range, relative and absolute distance perception, and visual fatigue. Here, we present results of the two tasks concerning distance perception.

PURPOSE To investigate the degree of visual acuity in workers with intellectual disabilities and the impact of vision on their working conditions. METHODS We recruited 224 workers (mean age 43.77 years, SD ± 12.96; range, 19-72 years) from a workshop for those with intellectual disabilities, to participate in a vision examination program. The assessment consisted of objective refraction, visual acuity, ocular motility, near-point of convergence, cover/uncover test, stereo acuity and colour perception. Individuals with vision deficits were fitted with spectacles following the screening program. RESULTS Within the past three years, 38.9 per cent of the participants received eye care, 14.3 per cent of participants had not received eye care in more than three years, and 6.7 per cent had not received any eye care. As many as 39.7 per cent of participants did not know whether they had ever received eye care. Entering visual acuity for far vision was 0.52 dec (-0.29 logMAR) and 0.42 dec (-0.38 logMAR) for near vision. Only 14.9 per cent, 11 of all participants aged ≥50 years, owned spectacles for near vision before the examination. After subjective determination of refraction, best corrected visual acuity for far vision was 0.61 dec (-0.22 logMAR) and 0.56 dec (-0.25 logMAR) for near vision (in both cases with p < 0.001). After the examination, 44.6 per cent (33) of all workers aged ≥50 years received a recommendation for reading or bifocal spectacles. In 46 per cent of workers, the threshold of stereopsis was higher than 63 arc seconds, and some form of colour vision deficiency was measured in 12.5 per cent of participants. CONCLUSIONS Workers with intellectual disabilities are often unaware of their visual deficits. We found that some of their abnormalities can be solved by appropriate optical means and that they could benefit from regular eye care. These workers should be encouraged to be tested and to improve their vision with appropriate lenses.

Some children, usually between the ages of 6 and 10, present with vision loss that cannot be explained on the basis of the physical findings. Studies exploring the possibilities of retinal, optic nerve, or cortical abnormalities yield normal results, yet the child has a variable combination of visual acuity loss, color vision defects, stereo acuity loss, and visual field deficits. While malingering adults who fake vision loss are generally after monetary compensation or other tangible gains, children with nonorganic vision loss generally fall into one of two groups: (1) Those who want their parents to buy them glasses, many times because their friends have them and they do not, and (2) those who utilize, most of the time in a subconscious fashion, the vision loss to gain the attention of their family members and the eye doctor because of an underlying anxiety-producing situation such as stress at home or in school or sometimes abuse or psychiatric illness.

Purpose We have shown previously that amblyopia involves impaired detection of asynchrony between auditory and visual events. To distinguish whether this impairment represents a defect in temporal integration or nonintegrative multisensory processing (e.g., cross-modal matching), we used the temporal ventriloquism effect in which visual temporal order judgment (TOJ) is normally enhanced by a lagging auditory click. Methods Participants with amblyopia (n = 9) and normally sighted controls (n = 9) performed a visual TOJ task. Pairs of clicks accompanied the two lights such that the first click preceded the first light, or second click lagged the second light by 100, 200, or 450 ms. Baseline audiovisual synchrony and visual-only conditions also were tested. Results Within both groups, just noticeable differences for the visual TOJ task were significantly reduced compared with baseline in the 100- and 200-ms click lag conditions. Within the amblyopia group, poorer stereo acuity and poorer visual acuity in the amblyopic eye were significantly associated with greater enhancement in visual TOJ performance in the 200-ms click lag condition. Conclusions Audiovisual temporal integration is intact in amblyopia, as indicated by perceptual enhancement in the temporal ventriloquism effect. Furthermore, poorer stereo acuity and poorer visual acuity in the amblyopic eye are associated with a widened temporal binding window for the effect. These findings suggest that previously reported abnormalities in audiovisual multisensory processing may result from impaired cross-modal matching rather than a diminished capacity for temporal audiovisual integration.

Introduction: Preschool children are reported to have visual deficits ranging from 5 to 29% . Children are unable to understand their symptoms, communicate it, hence early detection and intervention remains a challenge. Usually there is no manifestation of the visual disorder and are unheeded. Purpose: To determine the ocular morbidity among 3 to 6 year old children visiting a tertiary care hospital. Method and procedures : Ethical Committee approval was obtained. Children with developmental delay, non co-operation and parental reluctance were exclusion criteria for the study. Each child was assessed with E chart for vision, stereo acuity measurement with randot preschool, dry refraction, anterior and posterior segment evaluation and cycloplegic refraction. Descriptive statistics and chi square tests were employed for statistical analysis. Results: Two hundred eyes (100 participants) were analyzed. 52% were boys and 48% girls. Mean age was 64.6± 12.3 months. Refractive error was observed in 80 eyes(40%) ,45 eyes(22.5%) had amblyopia, anterior segment disorders were noted in 24 eyes (12%) and squint observed in 5 eyes(2.5%). Conclusion: Refractive error, amblyopia, anterior segment disorders, squint and posterior segment pathology were the ocular morbidity found in 3 to 6 year old children.

PURPOSE The purpose of this study was to develop a convenient test of stereopsis in the clinic that is both robust and reliable and capable of providing a measure of variability necessary to make valid comparisons between measurements obtained at different occasions or under different conditions. METHODS Stereo acuity was measured based on principles derived from the laboratory measurement of stereopsis (i.e., staircase method). Potential premeasurement compensations are described if there is a significant degree of ocular misalignment, reduced visual acuity, or aniseikonia. Forty-six adults at McGill University, 44 adults at Auckland University, and 51 adults from the University of Bradford, with an age range of 20 to 65 years old and normal or corrected-to-normal vision participated in this study. RESULTS Stereo acuity within this normal population was widely distributed, with a significant percentage (28%) of the population with only coarse stereo (>300 arc seconds). Across subjects, the SD was approximately 25% of the mean. Measurements at two different times were strongly (r = 0.79) and significantly (P < 0.001) correlated, with little to no significant (P = 0.79) bias (0.01) between test and retest measures of stereopsis. CONCLUSIONS The application enables measurements over the wide disparity range and not just at the finest disparities. In addition, it allows changes in stereopsis of the order of 1.9 to be statistically distinguished.