AbstractA research program investigating correctable issues in Functional Binocular Vision (FBV) related optometric variables to responses from a symptom survey and reading test results. The study was mounted with no explicit attention to measurement modeling. Data from this research program were retrospectively analyzed with the aims of evaluating the potential for learning from the existing observations, and for improving the study design in future iterations. Results suggest that the physical and psychological measurements of vision combine into a model of FBV that could be standardized and deployed for use in diagnosing significant numbers of untreated vision problems negatively impacting learning outcomes.

This study explores possibilities for productively studying and modelling vision using a probabilistic approach prioritizing the estimation and comparison of linear measures. Visual optometry, survey ratings, and reading assessment data are evaluated in a common frame of reference, with the aim of determining the extent to which an overall model of functional binocular vision might be feasible. The data available for study were not assembled, however, with this explicit aim in mind but appear to incorporate features justifying a preliminary exploration of the possibility that further study would be warranted. Preliminary results include estimates of optometric, survey, and assessment results in a common multidimensional framework, and regression predictions of reading fluency from visual skills and acuity optometry, and a survey of convergence insufficiency symptoms.

Studies suggest that poor reading can be related to poor binocular visual skills, such as vergence. It has been difficult to relate reading directly to such skills, however, because most datasets lack sufficient quantitative measures of relevant skills. In a prior study, MKP had gathered data from 1,062 students, ages 8-11; each subject had quantitative symptom and optometric measures. On re-examining this dataset with WPF, we constructed a variable called Functional Binocular Vision (FBV), by using a probabilistic approach that prioritized the estimation and comparison of linear measures. Besides demonstrating that FBV is robust and reliable, we also showed that it is not related to visual acuity. In the present study, we examined the relationship among FBV, acuity, and reading. In the original MKP study, a subset of subjects participated in an in-school intervention designed to improve visual skills using a computer program. The program kept track of 10 indicators (latency and accuracy for each of 5 training modules, each relating to a defined visual skill). These students also had sustained oral reading fluency measures taken during the intervention. Regression analysis of FBV variables against oral reading fluency scores had a significant adjusted R squared (R2) of 0.61; when acuity entered the regression equation, the R2 dropped to 0.44. When we examined the variables that changed with visual skill training, we found that binocular (FBV) and symptom (CISS) scores changed with reading, but acuity did not. We conclude: (a) Functional Binocular Vision (FBV) is a robust and useful construct that can predict oral fluency reading performance independent of Snellen acuity, and (b) training visual skills can improve reading outcomes.

Though it seems to be a natural process of physical development, not everyone learns on their own how to use their eyes effectively. Poor binocular vision skills negatively impact a wide range of daily life activities, including reading. This study extends previous work using existing data in multidimensional causal Rasch models of vision. Optometry, survey, and reading assessment data are evaluated in a common frame of reference. Thirty-three students performed vergence and tracking exercises in about 12 to 38 sessions each involving a sequence of five computerized training modules. The number of training modules experienced in any given session ranged from one to five. There were 4, 064 total measured cases, with about 123 measures per student. Paired comparison t-tests of early and late measures show significant gains in vision quality. Two regression models predict reading scores on the basis of vision data. Results support further study of how training in Functional Binocular Vision might contribute to improved outcomes in reading education.

Obtaining a clear image of the world depends on good eye coordination ("binocular vision"). Yet no standard exists by which to determine a threshold for good vs poor binocular vision, as exists for the eye chart and visual acuity. We asked whether data on the signs and symptoms related to binocular vision are sufficiently consistent with children's self-reported visual symptoms to substantiate a construct model of Functional Binocular Vision (FBV), and then whether that model can be used to aggregate clinical and survey observations into a meaningful diagnostic measure. Data on visual symptoms from 1,100 children attending school in Los Angeles were obtained using the Convergence Insufficiency Symptom Survey (CISS); and for more than 300 students in that sample, 35 additional measures were taken, including acuity, cover test near and far, near point of convergence, near point of accommodation, accommodative facility, vergence ranges, tracking ability, and oral reading fluency. A preliminary analysis of data from the 15-item, 5-category CISS and 15 clinical variables from 103 grade school students who reported convergence problems (CISS scores of 16 or higher) suggests that the clinical and survey observations will be optimally combined in a multidimensional model.

Background: Some post-LASIK patients complain of blurry distance vision months after refractive surgery, despite good corneal healing and negligible refractive error. We postulated that perceiving blur in the absence of refractive error or significant monocular aberrations might result from poor binocular control. Binocular vision testing in a series of such patients revealed convergence problems in 83% of cases. Case Reports: We report on 8 patients (average age 37.4 yrs) who completed up to 40 sessions of vision therapy (VT), either completely via computer or in a combination of computer orthoptics and office vision therapy. Seven patients had received LASIK; one had PRK. Optometric measurements and symptoms were recorded before and after VT treatment, starting at least 3 months after refractive surgery. Near point of convergence improved in 7 cases following VT, and convergence break and/or recovery improved in 6 cases. Six cases reported symptom reduction, and pre-presbyopic cases tended to improve accommodative facility. The number of binocular functions showing improvement per case correlated with the number of VT sessions completed. Convergence changes were statistically significant when pre-/post-VT data were compared for these cases as a group. Conclusion: Patients complaining of distance blur following refractive surgery may have undiagnosed binocular vision problems. VT incorporating an internet orthoptics component improved convergence ability in the cases reported here, and most patients reported symptomatic relief.

Following refractive surgery, some patients (less than 1%) complain of poor vision even though their refraction has been optimized. Upon examination, most of these patients exhibit binocular or accommodative disorders. This project began an investigation into whether an internet-based computer program that provides practice in binocular convergence, divergence, and fusion ranges can alleviate symptoms and improve visual function in post-Lasik patients with binocular dysfunction. Twelve patients, each 20/20 or better, were examined post-surgery for convergence range, accommodative facility, and other indicators of visual function. All had accommodative spasm and/or convergence insufficiency. Nine of the patients completed 20 or more sessions of an internet-based psychophysically rigorous visual skills training program. Sessions were 20 minutes/day, 3–5 days/ week. Binocular function improved significantly in six patients (67%). The other three also improved, but required additional in-office vision therapy to reach their therapeutic goals. The results show that binocular vision can be improved post-surgery in patients with binocular dysfunction. They also suggest that the identification of binocular disorders prior to surgery may be important, so that patients understand they may require some form of vision therapy post-surgery. Whether strengthening binocular function prior to surgery would eliminate post-surgical complaints remains to be determined.

Instruments for assessing visual function are valuable tools for optometry, ophthalmology, vision science, education, and public health. Inspired by my observations in the Teller lab, with Dobson, on the process of developing a useful clinical tool from laboratory work, I present four examples of functional vision tests that are made of paper and currently used in the field: the Amsler Grid, the Pelli-Robson Contrast Sensitivity Chart, the Teller Acuity Cards, and the Developmental Eye Movement Test. All are characterized by ease of use and rigorous design. All are either being used with children or have the potential to be so. Each tool is reviewed in terms of its development, with a view toward similarities in the steps or process taken. The goal is to encourage the further development of the functional vision assessments already in existence, and to urge scientists and clinicians alike to consider ways in which their own work can be translated into clinically useful, simple paper tools. (Optom Vis Sci 2009;86:613-618)

The lateral eye of the horseshoe crab has been a useful and productive model for vision research; it is complex enough to be interesting, yet simple enough to be understood. Extensive studies of this eye have yielded fundamental insights about how eyes of other animals, including humans, encode and process visual information. Lateral inhibition, light adaptation, and efferent-mediated circadian rhythms are just a few of the numerous physiological properties that were first uncovered through experiments on the horseshoe crab eye. We always speak about "THE horseshoe crab," and indeed, all of the studies and advances have been made with the eye of a particular species. Limulus polyphemus, which inhabits the waters along the eastern shores of North and Central America. But there are actually four extant species of horseshoe crabs—one of them. Tachypleus tridentatus, inhabits the shores of Japan. In the following article. T. Saito and his colleagues compare the properties of the eyes of Tachypleus with those of the standard model. Limulus. Saito et al. have found that, although the retinal sensitivity of the lateral eyes of Tachypleus and Limulus shows nearly the same circadian rhythms, the underlying mechanisms are different. The Limulus eye increases in sensitivity at night primarily by catching more photons, whereas the Tachypleus eye shows, in addition, a substantial increase in photoreceptor gain: i.e., an enhanced response of the photoreceptors to absorbed photons. This difference could be explained by the fact that the lateral eyes of Tachypleus are smaller than those of Limulus (see Fig. 1): moreover these smaller eyes contain fewer, smaller ommatidia that cannot catch as many photons as those of Limulus. So the increased response of the Tachypleus photoreceptors to each photon they absorb may be a compensatory adaptation. In short, what the small Tachypleus eye lacks in photon catch, it may make up in gain. Once again we find that although the functions of homologous tissues and cells are similar, they are never exactly the same, and that important and unexpected lessons can be learned in even small species differences.

BACKGROUND: Even though poor readers often have poor visual skills, such as binocular coordination and oculomotor control, students' visual skills are rarely assessed. Computer assessments have the potential to assist in identifying students whose visual skills are deficient. This study compared assessments made by an Internet-based computer orthoptics program with those of an on-site vision therapist.METHODS: Students (N = 41) in grades 1 through 8, reading at least 2 levels below grade, were assessed for visual skill dysfunction (including binocular fusion and tracking ability) by a vision therapist at their school in Wisconsin. The therapist determined whether the student had adequate visual skills based on clinical and behavioral observations. A "remote" investigator located in California determined the adequacy of accommodative facility, tracking, and vergence skills in the same students, based on quantitative progress through the modules of an Internet-based computer orthoptics training program during 3 assessment sessions.RESULTS: The on-site therapist made 33 referrals for possible visual skills training (80%). The remote investigator made 25 referrals (61%), all of which were consistent with referrals made by the on-site therapist; thus, no false-positives occurred when using the remote assessment technique. The 8 additional referrals by the therapist were attributed to the ability to observe student behavior during assessment.CONCLUSIONS: Remote assessment of visual skills via an Internet orthoptics program may provide a simple means to detect visual skill problems experienced by poor readers. Optometry 2009;80:61-69

BACKGROUND:Oculomotor control has been implicated as a factor when reading is poor, but few studies exist for adolescents.METHODS:The saccadic eye movement efficiency of 684 ninth grade students, identified as poor readers in 5 California high schools, was quantified using the Developmental Eye Movement test. Frequency distributions were produced from scores on vertical and horizontal components, and gender and test-retest factors were considered during analysis.RESULTS:Vertical times were within 1 standard deviation of normal for eighth grade. However, horizontal (saccadic) times were typical of grade 3, and the average number of errors on the horizontal test was typical of grade 2. Boys and girls performed similarly. Results of retests showed slightly improved horizontal times and fewer errors, but the grade level equivalents remained dramatically low. Overall, fewer than 10% of students scored above the 50th percentile for eighth grade.CONCLUSION:The results indicate that poor readers in high school may be at high risk for poor saccadic tracking skill.

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.

BACKGROUND:Prior findings suggest that poor readers tend to have poor visual skills, but few reports give full frequency distributions of skill variables, and little data are available for adolescents.METHODS:Visual skills and visual acuity were measured in 461 students (average age 15.4 years) in 4 California high schools within the same school district. Participating students had been identified by their schools as poor readers. Standard optometric tests and published criteria for "adequate" or "weak" visual skills were used.RESULTS:In this sample, 80% of the students were found to be inadequate or weak in 1 or more of the following visual skills: binocular fusion ranges at near, accommodative facility, and convergence near point. More students were deficient in binocular fusion range than in either accommodative function or near point of convergence. In contrast, only 17% had deficient visual acuity--20/40 or worse in 1 eye--the standard model of deficiency for school vision screenings.CONCLUSION:The results support and extend previous studies showing that large numbers of poor readers in high school may be at high risk for visual skills dysfunction.