Randot Preschool Research Articles

Stereopsis Results at 4.5 Years of Age in the Infant Aphakia Treatment Study

To determine whether stereopsis of infants treated for monocular cataracts varies with the type of optical correction used. Randomized prospective clinical trial. The Infant Aphakia Treatment Study randomized 114 patients with unilateral cataracts at age 1-7 months to either primary intraocular lens (IOL) or contact lens correction. At 4.5 years of age a masked examiner assessed stereopsis on these patients using 3 different tests: (1) Frisby; (2) Randot Preschool; and (3) Titmus Fly. Twenty-eight patients (25%) had a positive response to at least 1 of the stereopsis tests. There was no statistically significant difference in stereopsis between the 2 treatment groups: Frisby (contact lens, 6 [11%]; IOL, 7 [13%]; P = .99), Randot (contact lens, 3 [6%]; IOL, 1 [2%]; P = .62), or Titmus (contact lens, 8 [15%]; IOL, 13 [23%]; P = .34). The median age at surgery for patients with stereopsis was younger than for those without stereopsis (1.2 vs 2.4 months; P = .002). The median visual acuity for patients with stereopsis was better than for those without stereopsis (20/40 vs 20/252; P = .0003). The type of optical correction did not influence stereopsis outcomes. However, 2 other factors did: age at surgery and visual acuity in the treated eye at age 4.5 years. Early surgery for unilateral congenital cataract and the presence of visual acuity better than or equal to 20/40 appear to be more important than the type of initial optical correction used for the development of stereopsis.

Associations between health-related quality of life and the decision to perform surgery for childhood intermittent exotropia.

To assess associations between health-related quality of life (HRQOL) and the decision to perform strabismus surgery for children with intermittent exotropia. Retrospective chart review. Children with intermittent exotropia. Included subjects, identified in a clinical practice, had assessment of HRQOL using the intermittent exotropia questionnaire (IXTQ), comprising child, proxy, and parent components (parent domains: function, psychosocial, and surgery). The IXTQ scores were evaluated for association with surgery, along with standard clinical measures: prism and alternate cover test (PACT), stereoacuity, and control score (mean of the 3 most recent scores). Included data were from preoperative examination (surgical cohort) or from most recent follow-up examination (nonsurgical cohort). Univariate and multivariate logistic regression analyses were performed, and relative risk (RR) ratios were calculated. Spearman rank correlations were calculated to identify highly correlated items. Association of individual factors with the decision to perform surgery, calculated using RR ratios. One hundred six children with intermittent exotropia (median age, 6 years; range, 2-16 years) were eligible for inclusion. Nineteen (18%) of 106 underwent surgery. Using all available data, the IXTQ proxy score, IXTQ parent function score, IXTQ parent psychosocial score, distance control score, near control score, near PACT, and Randot Preschool stereoacuity (Stereoptical Co, Inc, Chicago, IL) were associated with undergoing surgery (P<0.1). Sixty-nine of 106 patients had complete data on all factors identified in univariate analysis and were included in multivariate analyses. Fourteen (20%) of these 69 patients underwent surgery. In multivariate analyses, poor distance control score (RR, 1.83; 95% confidence interval [CI], 1.25-2.68) and reduced IXTQ parent function score (RR, 0.96; 95% CI, 0.92-0.99) were associated with surgical intervention. Repeat multivariate analyses retaining only 1 of the highly correlated items showed IXTQ proxy, IXTQ parent psychosocial, larger near PACT, and worse near control were also associated with surgery. After accounting for poorer exodeviation control at distance, reduced parent and proxy HRQOL were associated with undergoing strabismus surgery for childhood intermittent exotropia. Recognizing reduced parental HRQOL may be important, with a possible role for educational or counselling interventions.

Fixation instability in anisometropic children with reduced stereopsis

Hyperopic anisometropia in children can be associated with abnormal stereoacuity and "microstrabismus," a small temporalward "flick" as each eye assumes fixation on cover testing. The prevailing hypothesis is that abnormal sensory experience leads to foveal suppression and, subsequently, secondary microstrabismus. This study investigated the hypothesis that disruption of bifoveal fusion by anisometropia directly affects ocular motor function. A total of 94 children with hyperopic anisometropia (ages 5-13 years) were evaluated prospectively between June 2010 and December 2012 with the use of the Nidek MP-1 microperimeter. Fixation instability was quantified by the area of the bivariate contour ellipse that included 95% of fixation points during a 30-second test interval. Each eye movement waveform during the 30-second test interval also was examined with the use of custom software and classified as normal, fusion maldevelopment nystagmus (FMNS), or infantile nystagmus. Finally, the Randot Preschool Stereoacuity Test (Stereo Optical Company Inc, Chicago, IL) was administered. Stereoacuity was correlated with fixation instability (Spearman r = 0.50; 95% CI, 0.33-0.64); visual acuity was more weakly correlated (r = 0.28). All children with normal stereoacuity had stable fixation, children with subnormal stereoacuity had fixation instability, and those with nil stereoacuity had the most instability. Eye movement records during attempted fixation were of sufficient quality for classification in 81 children; 61% of those with reduced stereoacuity and 88% of those with nil stereoacuity had FMNS eye movement waveforms. Our data support the hypothesis that the binocular decorrelation caused by anisometropia can disrupt ocular motor development, resulting in FMNS and its temporalward refoveating "flicks" that may mimic microstrabismus.

Quantitative Measurement of Interocular Suppression in Anisometropic Amblyopia: A Case-Control Study

The aims of this study were to assess (1) the relationship between interocular suppression and visual function in patients with anisometropic amblyopia, (2) whether suppression can be simulated in matched controls using monocular defocus or neutral density filters, (3) the effects of spectacle or rigid gas-permeable contact lens correction on suppression in patients with anisometropic amblyopia, and (4) the relationship between interocular suppression and outcomes of occlusion therapy. Case-control study (aims 1-3) and cohort study (aim 4). Forty-five participants with anisometropic amblyopia and 45 matched controls (mean age, 8.8 years for both groups). Interocular suppression was assessed using Bagolini striated lenses, neutral density filters, and an objective psychophysical technique that measures the amount of contrast imbalance between the 2 eyes that is required to overcome suppression (dichoptic motion coherence thresholds). Visual acuity was assessed using a logarithm minimum angle of resolution tumbling E chart and stereopsis using the Randot preschool test. Interocular suppression assessed using dichoptic motion coherence thresholds. Patients exhibited significantly stronger suppression than controls, and stronger suppression was correlated significantly with poorer visual acuity in amblyopic eyes. Reducing monocular acuity in controls to match that of cases using neutral density filters (luminance reduction) resulted in levels of interocular suppression comparable with that in patients. This was not the case for monocular defocus (optical blur). Rigid gas-permeable contact lens correction resulted in less suppression than spectacle correction, and stronger suppression was associated with poorer outcomes after occlusion therapy. Interocular suppression plays a key role in the visual deficits associated with anisometropic amblyopia and can be simulated in controls by inducing a luminance difference between the eyes. Accurate quantification of suppression using the dichoptic motion coherence threshold technique may provide useful information for the management and treatment of anisometropic amblyopia. Proprietary or commercial disclosure may be found after the references.

High sensitivity and specificity of the Pediatric Vision Scanner in detecting strabismus and amblyopia in preschool children

The Pediatric Vision Scanner (PVS) directly detects strabismus and amblyopia by analyzing binocular scans for the presence or absence of birefringence, which is characteristic of steady, bifoveal fixation. In a preliminary study (AAPOS 2012), the PVS demonstrated 98% sensitivity and 88% specificity. Here we report the sensitivity and specificity for a large cohort, confidence intervals, and analyses of screening errors. 250 children (2-6y) were enrolled; 103 controls and 147 with strabismus and/or amblyopia. In addition to the PVS, children were tested with the SureSight autorefractor and the Randot Preschool Stereoacuity test (RPST). Each test yielded a recommendation of “pass” or “refer.” A comprehensive pediatric ophthalmic examination served as the gold-standard. The PVS correctly identified 144 of 147 children with strabismus and/or amblyopia; sensitivity = 98% (95%CI: 95-100%). The PVS correctly identified 89 of 102 control children; specificity = 87% (95% CI, 79%-96%). The SureSight misclassified 81 children, failing to detect 49 children with strabismus and/or amblyopia and over-referring 18 children with astigmatism. The RPST misclassified 51 children, including similar numbers of affected and control children. Misclassifications were not consistent across tests. Using Bayesian analysis to estimate the performance of each test in a preschool screening setting (assuming a prevalence of 4%), accuracies of 88%, 69%, and 77% were predicted for the PVS, SureSight, and RPST tests, respectively. The PVS identifies children with strabismus and/or amblyopia with high sensitivity, outperforming the SureSight and the RPST. Preschool vision screening may be more efficient with a device that directly detects strabismus and/or amblyopia.

Diagnostic reliability and normative values of stereoacuity tests in preschool-aged children

AimTo establish the range of normal stereoacuity thresholds and evaluate the diagnostic reliability of stereoacuity tests in preschool-aged children.Methods1606 children, aged 24–72 months, had detailed eye examinations and stereoacuity testing....

Testability of refraction, stereopsis, and other ocular measures in preschool children: The Sydney Paediatric Eye Disease Study

To determine the testability and lower age limits for applying common eye tests to preschool children. Investigators from the Sydney Paediatric Eye Disease Study examined 2,461 children aged 6 to 72 months between 2007 and 2009. Cycloplegic autorefraction was measured with Retinomax and Canon autorefractors. Ocular biometry was measured by the use of IOLMaster in children aged >30 months. The Randot Preschool Stereoacuity test, Lang-Stereotest II, and the Stereo Smile II test were administered to assess stereoacuity. Fundus photography was performed with the subjects' pupils dilated. Testability was defined as the ability to successfully complete tests in both eyes. There were 2,189 children with complete data. Most were testable with the Retinomax (71.8%) and Canon (66.0%) autorefractors. Testability improved with age (P for trend <0.0001) for both, and Retinomax achieved >70% testability when a subject was 24 months of age, half the age limit (48 months) found for Canon. IOLMaster was mostly testable in children aged 48+ months. Lang-Stereotest II could be used in children aged 6 months and achieved the greatest testability (94.4%) of all stereotests. White children performed better than children of some other ethnicities on Randot (P = 0.007), with girls performing better than boys (P = 0.01). Bilateral photography was achieved in >70% of preschool children 48 months of age. The testability of all measures was strongly age related, with mostly no sex or ethnicity effects found. The handheld Retinomax could be tested in >70% of children aged 24 months, younger than that found for the stationary Canon autorefractor (48 months). Testability measures for most eye tests in this preschool sample are comparable to other preschool studies.

Stability of near stereoacuity in childhood intermittent exotropia

To investigate the course of near stereoacuity in a cohort of children with untreated intermittent exotropia. A total of 95 children ages 2-16 years with untreated intermittent exotropia were identified who had measurements of near stereoacuity using the Preschool Randot (PSR) test on at least 2 successive examinations, with no intervening treatment. Deterioration was defined as a drop of at least 3 octaves, as determined by test-retest data. Alternative secondary analyses were performed defining deterioration as a drop of at least 2 octaves or as a transition from normal to subnormal. The main outcome measure was the deterioration rate calculated at 1 and 2 years using a Kaplan-Meier survival analysis. For near stereoacuity, the rate of decreasing 3 or more octaves was 2% (95% CI, 0%-6%) at 1 year and 7% (95% CI, 0%-16%) at 2 years. The alternative secondary analyses revealed similar low deterioration rates. In most cases of apparent deterioration, near stereoacuity returned to baseline levels without treatment. For children with untreated intermittent exotropia, deterioration in near stereoacuity at 1 and 2 years is infrequent. Therefore, performing surgery for intermittent exotropia to proactively prevent deterioration of near stereoacuity cannot be justified. Retesting stereoacuity is critical to determine whether any measured decrease in stereoacuity is real.

Stereoacuity in children with anisometropic amblyopia

To determine factors associated with pretreatment and posttreatment stereoacuity in subjects with moderate anisometropic amblyopia. Data for subjects enrolled in seven studies conducted by the Pediatric Eye Disease Investigator Group were pooled. The sample included 633 subjects aged 3 to <18 years with anisometropic amblyopia, no heterotropia observed by cover test, and baseline amblyopic eye acuity of 20/100 or better. A subset included 248 subjects who were treated with patching or Bangerter filters and had stereoacuity testing at both the baseline and outcome examinations. Multivariate regression models identified factors associated with baseline stereoacuity and with outcome stereoacuity as measured by the Randot Preschool Stereoacuity test. Better baseline stereoacuity was associated with better baseline amblyopic eye acuity (P < 0.001), less anisometropia (P = 0.03), and anisometropia due to astigmatism alone (P < 0.001). Better outcome stereoacuity was associated with better baseline stereoacuity (P < 0.001) and better amblyopic eye acuity at outcome (P < 0.001). Among 48 subjects whose amblyopic eye visual acuity at outcome was 20/25 or better and within one line of the fellow eye, stereoacuity was worse than that of children with normal vision of the same age. In children with anisometropic amblyopia of 20/40 to 20/100 inclusive, better posttreatment stereoacuity is associated with better baseline stereoacuity and better posttreatment amblyopic eye acuity. Even if their visual acuity deficit resolves, many children with anisometropic amblyopia have stereoacuity worse than that of nonamblyopic children of the same age.

Quantitative measurement of interocular suppression in children with amblyopia

Previously it has been shown that intensive training aimed at reducing interocular suppression leads to improvement in amblyopic eye acuity as well as binocular vision in adults with strabismic amblyopia (Hess et al., 2010). In the current study we explored the possibility of using this approach to measure interocular suppression in children with amblyopia. We compared children (8–12 years old) with unilateral anisometropic and/or strabismic amblyopia to age-matched control children with normal visual acuity and no ocular pathology. Visual acuity was measured using the Regan high contrast chart; stereopsis was evaluated using the Randot preschool and the Randot circles test. Motion coherence thresholds for left-right direction discrimination were determined using a binocular global motion stimulus presented with virtual reality goggles (eMagin). The proportion of signal dots among noise dots was varied with a staircase procedure. In dichoptic viewing, high contrast signal dots were presented to the amblyopic eye (one eye of control subjects) while low contrast noise dots were presented to the fellow eye (the other eye of control subjects) at the motion coherence threshold. The contrast of the noise dots was increased until performance reached chance levels. Higher contrast thresholds indicated less interocular suppression. Regardless of their stereo acuity, all children in the amblyopic group exhibited some degree of binocular function on the dichoptic motion task. The amount of interocular suppression was high in the strabismic group and low in the anisometropic group indicating that interocular suppression is more potent in strabismic than in anisometropic amblyopia (Harrad and Hess, 1992). We have shown that the Hess et al stimuli can be used to measure both interocular suppression and residual binocular function in children with amblyopia. Interocular suppression is an established mechanism for visual loss in strabismic amblyopia; our results suggest it is less of a problem in anisometropic amblyopia.

Stereoacuity Thresholds before and after Visual Acuity Testing

To compare stereoacuity thresholds before and after visual acuity testing in patients with intermittent strabismus and in controls. Prospective cohort study. Eighty-eight patients (41 with intermittent strabismus and 47 controls) with measurable stereoacuity on their initial stereoacuity test were enrolled prospectively. Stereoacuity was measured before and immediately after visual acuity testing using the near Preschool Randot and Distance Randot stereotests. Stereoacuity was transformed to log units for analysis. Change in stereoacuity thresholds (log seconds of arc [arcsec]). There was no overall deterioration in distance stereoacuity or near stereoacuity thresholds in either the intermittent strabismus or control groups. The mean change for patients with intermittent strabismus was 0.02 log arcsec (95% confidence interval [CI], -0.02 to 0.06) for near stereoacuity and 0.04 log arcsec (95% CI, -0.01 to 0.09) for distance stereoacuity. Control patients demonstrated a mean change of 0.03 log arcsec (95% CI, -0.01 to 0.06) for near stereoacuity and 0.01 log arcsec (95% CI, -0.06 to 0.08) for distance stereoacuity. These mean changes correspond to less than approximately one eighth of an octave. For individual patients, deterioration in stereoacuity beyond previously reported test-retest variability (0.6 log arcsec or more) was not observed in patients with intermittent strabismus or controls using either test. Stereoacuity thresholds do not deteriorate after visual acuity testing, and therefore measurements of stereoacuity do not need to precede visual acuity measurement or other tests that involve short periods of dissociation. The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Classification and Misclassification of Sensory Monofixation in Intermittent Exotropia

The course of intermittent exotropia and response to surgery may depend on whether there is underlying monofixation. The purpose of this study was to report the prevalence of sensory monofixation in intermittent exotropia using different stereotests and to determine the risk of misclassifying monofixation based on a single administration of each test. Retrospective case review of children with intermittent exotropia. Forty-four children were identified for whom Preschool Randot, Frisby, and Titmus stereoacuity were measured at a single examination. Ninety-two children were identified with near stereoacuity measured on 2 sequential visits (Preschool Randot, n = 73; Frisby, n = 66; and Titmus, n = 40). Monofixation was defined as stereoacuity worse than previously published age-referenced normal thresholds, bifixation was defined as at least 40 arc seconds, and uncertain was defined as within normal range for age but worse than 40 arc seconds. In children measured by all 3 tests on the same visit, sensory monofixation occurred in 36% using Preschool Randot, in 48% using Titmus, and in 55% using Frisby (P > .1 for each comparison). There was poor agreement between Frisby and Preschool Randot when classifying monofixation in individual patients (P = .05). In children measured on sequential visits, misclassification occurred in 5% with Preschool Randot, in 13% with Titmus, and in 23% with Frisby (Preschool Randot vs Frisby, P = .005). Classification of monofixation depends on the stereotest used. Regardless of the stereotest, there is a risk of misclassifying monofixation on a single assessment. Potential misclassification needs to be considered in clinical practice and in study design.

The functional significance of stereopsis.

Purpose. Development or restoration of binocular vision is one of the key goals of strabismus management; however, the functional impact of stereoacuity has largely been neglected. Methods. Subjects aged 10 to 30 years with normal, reduced, or nil stereoacuity performed three tasks: Purdue pegboard (measured how many pegs placed in 30 seconds), bead threading (with two sizes of bead, to increase the difficulty; measured time taken to thread a number of beads), and water pouring (measured both accuracy and time). All tests were undertaken both with and without occlusion of one eye. Results. One hundred forty-three subjects were recruited, 32.9% (n = 47) with a manifest deviation. Performances on the pegboard and bead tasks were significantly worse in the nil stereoacuity group when compared with that of the normal stereoacuity group. On the large and small bead tasks, those with reduced stereoacuity were better than those with nil stereoacuity (when the Preschool Randot Stereoacuity Test [Stereo Optical Co, Inc., Chicago, IL] results were used to determine stereoacuity levels). Comparison of the short-term monocular conditions (those with normal stereoacuity but occluded) with nil stereoacuity showed that, on all measures, the performance was best in the nil stereoacuity group and was statistically significant for the large and small beads task, irrespective of which test result was used to define the stereoacuity levels. Conclusions. Performance on motor skills tasks was related to stereoacuity, with subjects with normal stereoacuity performing best on all tests. This quantifiable degradation in performance on some motor skill tasks supports the need to implement management strategies to maximize development of high-grade stereoacuity.

Defining Real Change in Measures of Stereoacuity

To establish the thresholds for "real change" in stereoacuity by defining long-term test-retest variability as 95% limits of agreement for 4 stereoacuity tests. Retrospective cohort study. We identified 36 patients (median, 17 years; range, 7-76) with any type of stable strabismus who had stereoacuity measured on 2 consecutive visits. Stable strabismus was defined as angle of deviation within 5 prism diopters by simultaneous prism and cover test and prism and alternating cover test. Stereoacuity was measured at near using the preschool Randot and the near Frisby stereotests and at distance using the Frisby-Davis distance (FD2) and the distance Randot stereotests. Stereoacuity was transformed to log units for analysis. The 95% limits of agreement were calculated based on a 1.96 multiple of the standard deviation of differences between test and retest. The 95% limits of agreement for change in stereoacuity thresholds at 2 consecutive visits. The 95% limits of agreement were 0.59 log arcsec for the preschool Randot, 0.24 for the near Frisby, 0.68 for the FD2, and 0.46 for the distance Randot. These values correspond with the following octave steps (doublings of threshold; e.g., 200-400 arcsec): preschool Randot, 1.95; near Frisby, 0.78; FD2, 2.27; and distance Randot, 1.52. A change of approximately 2 octaves of stereoacuity threshold are needed to exceed test-retest variability for most stereoacuity tests. Changes <2 octaves cannot be distinguished from test-retest variability. When used to guide patient management, caution should be taken in interpreting changes in stereoacuity of <2 octaves. The authors have no proprietary or commercial interest in any materials discussed in this article.

The effect of induced monocular blur on measures of stereoacuity

To determine the effect of induced monocular blur on stereoacuity measured with real depth and random dot tests. Monocular visual acuity deficits (range, 20/15 to 20/1600) were induced with 7 different Bangerter filters (<0.1, 0.1, 0.2, 0.3, 0.4, 0.8, and 1.0) in 15 visually normal adults. Stereoacuity was measured with Frisby and Frisby Davis Distance (FD2) real depth tests and Preschool Randot (PSR) and Distance Randot (DR) random dot tests. Stereoacuity results were grouped as either "fine" (<or=60 arcsec), "moderate" (>60 and <or=200 arcsec), or "coarse/nil" (>200 arcsec to nil) stereo. Across visual acuity deficits, stereoacuity was more severely degraded with random dot (PSR, DR) than with real depth (Frisby, FD2) tests. Degradation to worse-than-fine stereoacuity consistently occurred at 0.7 logMAR (20/100) or worse for Frisby, 0.1 logMAR (20/25) or worse for PSR, and 0.1 logMAR (20/25) or worse for FD2. There was no meaningful threshold for the DR because worse-than-fine stereoacuity was associated with -0.1 logMAR (20/15). Course/nil stereoacuity was consistently associated with 1.2 logMAR (20/320) or worse for Frisby, 0.8 logMAR (20/125) or worse for PSR, 1.1 logMAR (20/250) or worse for FD2, and 0.5 logMAR (20/63) or worse for DR. Stereoacuity thresholds are more easily degraded by reduced monocular visual acuity with the use of random dot tests (PSR and DR) than real depth tests (Frisby and FD2). We have defined levels of monocular visual acuity degradation associated with fine and nil stereoacuity. These findings have important implications for testing stereoacuity in clinical populations.

Associations between Anisometropia, Amblyopia, and Reduced Stereoacuity in a School-Aged Population with a High Prevalence of Astigmatism

To describe the relation between magnitude of anisometropia and interocular acuity difference (IAD), stereoacuity (SA), and the presence of amblyopia in school-aged members of a Native American tribe with a high prevalence of astigmatism. Refractive error (cycloplegic autorefraction confirmed by retinoscopy), best corrected monocular visual acuity (VA; Early Treatment Diabetic Retinopathy Study logMAR charts), and best corrected SA (Randot Preschool Stereoacuity Test) were measured in 4- to 13-year-old Tohono O'odham children (N = 972). Anisometropia was calculated in clinical notation (spherical equivalent and cylinder) and in two forms of vector notation that take into account interocular differences in both axis and cylinder magnitude. Astigmatism >or= 1.00 D was present in one or both eyes of 415 children (42.7%). Significant increases in IAD and presence of amblyopia (IAD >or= 2 logMAR lines) occurred, with >or=1 D of hyperopic anisometropia and >or=2 to 3 D of cylinder anisometropia. Significant decreases in SA occurred with >or=0.5 D of hyperopic, myopic, or cylinder anisometropia. Results for vector notation depended on the analysis used, but also showed disruption of SA at lower values of anisometropia than were associated with increases in IAD and presence of amblyopia. Best corrected IAD and presence of amblyopia are related to amount and type of refractive error difference (hyperopic, myopic, or cylindrical) between eyes. Disruption of best corrected random dot SA occurs with smaller interocular differences than those producing an increase in IAD, suggesting that the development of SA is particularly dependent on similarity of the refractive error between eyes.

Stereoacuity Testability in African-American and Hispanic Pre-School Children

To determine testability using the Randot Pre-school Stereoacuity Test in black and Hispanic children 30 to 72 months of age. A population-based cohort of children 30 to 72 months of age was administered the Randot Pre-school Stereoacuity Test, with presenting refractive correction, and before cover testing, visual acuity testing, or refraction. Children who could not point to specified two-dimensional demonstration pictures, and children who would not try to name or match random dot figures to the corresponding two-dimensional pictures, were classified as unable to perform the test. Children who were able to perform the task but could not correctly identify at least two 800-arcsecond random dot figures were classified as having no stereopsis, and were retested by another examiner. Stereoacuity testing was attempted in 1662 Hispanic and 1470 black children. Overall, 80% of children were able to be tested; 33% of children 30 to 36 months of age, 73% of children 37 to 48 months of age, 96% of children 49 to 60 months of age, and 98% of children 61 to 72 months of age were testable. Older children were significantly more likely to complete testing successfully than younger children (p < 0.0001). After adjusting for age, there was no significant ethnicity-related difference in testability (p = 0.19); however, there was a small but significant gender-related difference (p = 0.0002) with more girls (82%) than boys (77%) able to complete testing. Eighty percent of children aged 30 to 72 months can be tested using the Randot Pre-school Stereoacuity test. Testability increases steadily with age, and 97% of children over 48 months of age can complete the test. Testability does not differ between children of Hispanic and black ethnicity.

Comparative Efficacy of Penalization Methods in Moderate to Mild Amblyopia

To compare the efficacy and sensory outcome of pharmacologic and optical penalization in the treatment of moderate to mild amblyopia. Randomized clinical trial. In an institutional setting, two- to 10-year-old children with strabismic or anisometropic amblyopia (visual acuity in the amblyopic eye at least 20/60) who were cooperative to measure visual acuity using the logarithm of the minimum angle of resolution (logMAR) crowded Glasgow acuity cards were randomized into two groups of therapy (n=35 in each group), 1% atropine, and optical penalization with positive lenses, after stratification by cause of amblyopia. Visual acuity was tested by the logMAR crowded Glasgow acuity cards, after retinoscopic refraction, and deviation angle were measured by the simultaneous prism and cover or Krimsky test. Stereoacuity was determined using the Titmus fly test and Randot preschool or Randot circles stereoacuity test. Change in visual acuity of the amblyopic eye and in interocular difference of visual acuity after six months of amblyopia therapy was the main outcome measure; stereoacuity at six months of therapy was a secondary outcome measure. Thirty-one and 32 children completed the outcome examination in the atropine and optical penalization group, respectively. Average improvement in visual acuity of the amblyopic eye was larger in the atropine than in the optical penalization group (3.4 and 1.8 logMAR lines, respectively), as well as average improvement in interocular difference of visual acuity (2.8 and 1.3 logMAR lines, respectively). Better stereoacuity, but nonsignificantly different, was detected in the atropine group. Atropine penalization may be considered more effective than optical penalization with positive lenses.

Variability of Stereoacuity in Intermittent Exotropia

Distance stereoacuity is used to monitor deterioration of intermittent exotropia (IXT), but variability of stereoacuity has not been studied rigorously. The purpose of this study was to assess the variability of stereoacuity over one day in children with IXT. Prospective cohort study. Twelve children with IXT were recruited. Stereoacuity was assessed using the Frisby Davis Distance test and the Distance Randot test at distance, and the Frisby and Preschool Randot tests at near. Tests were repeated three or four times over the day, with at least two hours between assessments. The main outcome measure was variable stereoacuity defined as a change by two or more log levels between any two time points over the day. Variable stereoacuity at distance was found in five (42%) of 12 patients. Four (33%) of 12 patients demonstrated variable results using the Distance Randot test, three of whom also showed variable results using the Frisby Davis Distance test. One patient had variable results using the Frisby Davis Distance test only. Nine (75%) of 12 patients completed near stereoacuity testing; two (22%) of nine showed variable near stereoacuity. Two (22%) of nine showed variable results using the Preschool Randot test, one (11%) of whom also had variable results using the Frisby test. In some cases, stereoacuity changed from measurable stereoacuity on one assessment to nil on another. Nearly half of children with IXT show marked changes in stereoacuity over the course of a single day. When based on isolated measures, an apparent change in distance stereoacuity between visits should be interpreted with caution.

Improvement in distance stereoacuity following surgery for intermittent exotropia

To evaluate whether distance stereoacuity improves following surgery for intermittent exotropia using the Frisby Davis Distance (FD2) and Distance Randot stereotests. Eighteen patients (median age, 24 years; range, 5 to 68 years) with intermittent exotropia were prospectively enrolled. Stereoacuity was measured pre- and 6 weeks postoperatively using the FD2 and Frisby near tests (real depth tests) and Preschool Randot and Distance Randot tests (polaroid vectographs). Distance stereoacuity measured with the FD2 improved from a median preoperative value of 80 to 40 arcsec postoperatively (p = 0.04) and stereoacuity measured with the Distance Randot improved from a median of nil to 200 arcsec (p = 0.06). In those that had subnormal stereoacuity preoperatively, there was even more marked improvement in distance stereoacuity (FD2 median nil vs 40 arcsec, p = 0.002; Distance Randot median nil vs 200 arcsec, p = 0.004). Near stereoacuity measured with Frisby and Preschool Randot remained unchanged pre- to postoperatively (median, 60 and 80 arcsec, respectively). There was improvement in distance stereoacuity measured with both the FD2 and the Distance Randot stereotests in patients who underwent surgery for intermittent exotropia. The FD2 and Distance Randot may be useful outcome measures in future clinical trials of interventions for intermittent exotropia.