Random dot stereoacuity of preschool children. ALSPAC "Children in Focus" Study Team

Multifaceted Interactions of Stereoacuity, Inter-Ocular Suppression, and Fixation Eye Movement Abnormalities in Amblyopia and Strabismus

Purpose

Amblyopic and strabismus subjects experience inter-ocular suppression, impaired stereoacuity, and increased fixation instability. The purpose of the study was to investigate factors affecting suppression and stereoacuity and examine their relationship to fixation eye movement (FEM) abnormalities.

Methods

We recruited 14 controls and 46 amblyopic subjects (anisometropic = 18, strabismic = 14, and mixed = 14) and 11 subjects with strabismus without amblyopia. We utilized the dichoptic motion coherence test to quantify suppression, and stereoacuity was assessed using the Titmus Fly test. We recorded FEMs using high-resolution video-oculography and classified subjects that did not have nystagmus (n = 27) versus those with nystagmus (n = 32; fusion maldevelopment nystagmus [FMN], n = 10) and nystagmus that did not meet the criteria of FMN (n = 20). We also recorded FEMs under dichoptic viewing (DcV) at varied fellow eye (FE) contrasts and computed the amplitude and velocity of the fast and slow FEMs and vergence instability.

Results

Inter-ocular suppression and stereoacuity deficits were closely correlated with an amblyopic eye (AE), visual acuity, and strabismus angle. Subjects with nystagmus displayed more pronounced stereoacuity deficits than those without nystagmus. Strabismic subjects with and without amblyopia, who demonstrated a fixation switch at 100% FE contrast, had lower inter-ocular suppression than subjects lacking a fixation switch under DcV. Amplitude of fast FEMs and velocity of slow FEMs, and vergence instability were increased as the FE contrast was lowered in both amblyopic and strabismic subjects.

Conclusions

The current study highlights the intricate relationships between AE visual acuity, eye deviation, and FEM abnormalities on suppression and stereoacuity deficits and underscores the need to evaluate FEM abnormalities while assessing dichoptic treatment outcomes.

Postoperative outcome and influencing factors of strabismus surgery in infants aged 1-6 years

PURPOSE

To evaluate the postoperative outcome of strabismus surgery performed in children aged 1-6 years by investigating the change of the preoperative angle of deviation (AOD), elevation in adduction, best-corrected visual acuity (BCVA) and refractive error.

METHODS

Retrospective chart review of 62 children who received strabismus surgery between January 2018 and December 2021 at the Department of Ophthalmology and Optometry of the Medical University of Vienna. Age, sex, type of strabismus, AOD, BCVA, refractive error and visual acuity were evaluated with respect to the postoperative outcome.

RESULTS

Mean follow-up was 13.55 ± 11.38 months with a mean age of 3.94 ± 1.97 years (range: 1.0-6.0) at time of surgery. 74.19% of patients (n = 46) had isolated or combined esotropia, 12.90% (n = 8) had isolated or combined exotropia and 12.90% (n = 8) had isolated strabismus sursoadductorius. Mean preoperative AOD of 15.69 ± 16.91°/15.02 ± 14.88° (near/distance) decreased to 4.00 ± 9.18°/4.83 ± 7.32° (near/distance) at final follow-up (p < 0.001). BCVA improved from 0.26 ± 0.26/0.25 ± 0.23 (left/right) to 0.21 ± 0.25/0.20 ± 0.23 (left/right) (p = 0.038). There was no significant change regarding refractive error (p = 0.109) or elevation in adduction (p = 0.212). Success rate which was defined as a residual AOD of less than 10° was 74.19% (n = 46). In 3.23% (n = 2) retreatment was necessary.

CONCLUSION

Strabismus surgery in infants was shown to have a satisfactory outcome with a low retreatment rate. Surgical success rate was not linked to age, sex, type of strabismus or the preoperative parameters AOD, refractive error and visual acuity in this study.

Reduced perception-action dissociation in children with amblyopia

The functional distinction between vision-for-perception and vision-for-action is a key aspect of understanding the primate visual system. While this dissociation has been well-established in adulthood, its development and dependence on typical visual experience remain unclear. To address these questions, we examined two groups of children: typically developed children and those with amblyopia, who presumably have a sub-optimal visual experience. The Ponzo illusion, known to impact perception but not visuomotor behaviors across age groups, was employed to assess the extent of dissociation. Participants engaged in two tasks involving the Ponzo illusion: a grasping task (vision-for-action) and a manual estimation task (vision-for-perception), with objects placed on the "close" and "far" surfaces of the illusion. Typically developed children displayed grasping movements that were unaffected by the illusion, as their grasping apertures were scaled based on object size, independent of its location. In contrast, children with amblyopia exhibited a clear susceptibility to the illusion, showing larger apertures for objects placed on the 'far' surface of the illusion, and smaller apertures for objects placed on the 'close' surface. Interestingly, both groups of children demonstrated similar susceptibility to the illusion during the perceptual task, with objects placed on the far surface being perceived as longer compared to objects placed on the close surface. These findings shed light on the impact of atypical visual development on the emergence of the dissociation between perception and action, highlighting the crucial role of typical visual experience in establishing this distinction.

Dichoptic and Monocular Visual Acuity in Amblyopia

PURPOSE

Standard-of-care assessment for children with amblyopia includes measuring amblyopic eye best-corrected visual acuity (AE BCVA) with the fellow eye occluded. By definition, this abolishes the interocular suppression fundamental to amblyopia. Thus, measured AE BCVA may not accurately represent that eye's contribution to natural binocular viewing. We compared dichoptic and monocular AE BCVA and examined whether any differences were associated with eye-hand coordination or reading speed.

DESIGN

Cross-sectional study.

METHODS

Dichoptic and monocular AE BCVA of children aged 6-12 years (42 with amblyopia, 24 with recovered normal AE BCVA, 30 control) were measured. Stereoacuity, suppression, eye-hand coordination, and reading speed were also assessed.

RESULTS

Overall, 81% of amblyopic children had worse dichoptic than monocular AE BCVA (mean difference=0.15±0.11 logMAR; P < .0001), and 71% of children with recovered normal AE BCVA had worse dichoptic than monocular AE BCVA (mean difference = 0.20±0.17 logMAR, P < .0001). Controls had no significant difference. The difference between dichoptic and monocular AE BCVA was correlated with performance in standardized aiming/catching (r = -0.48, 95% CI -0.72, -0.14) and manual dexterity tasks (r = -0.37, 95% CI -0.62, -0.06), and with reading speed (r = -0.38, 95% CI -0.65, -0.03).

CONCLUSIONS

Dichoptic AE BCVA deficits were worse than monocular AE BCVA deficits and were associated with reduced stereoacuity and suppression, consistent with the hypothesis that binocular dysfunction plays a role. Further, impaired eye-hand coordination and slow reading were associated with dichoptic, but not monocular, AE BCVA. Some children with amblyopia may benefit from extra time for school tasks requiring eye-hand coordination or reading.

Percentile curves of stereacuity in a Spanish paediatric population

OBJECTIVE

The main objective of this study was to obtain percentile curves of stereoacuity in arc seconds for a Spanish population aged between three and twelve years of age.

MATERIALS AND METHODS

A descriptive, observational and transversal study was conducted, which included children aged between three and twelve years of age who did not present with any known ocular and/or systemic diseases. The convenience sampling method was used to select the sample from three schools and one hospital in the Community of Madrid. The Bueno-Matilla Vision Unit's random dot test was used to measure stereoacuity. A descriptive statistic was performed with the stereoacuity values that were obtained for the 5th, 10th, 25th, 50th, 75th, 90th and 95th percentiles.

RESULTS

The stereoacuity values of 1300 children were analysed. In the 50th percentile curve, it was determined that stereoacuity values close to 40 sec/arc were present from four years of age, and at four years and nine months, stereoacuity values close to 28 sec/arc were already being observed within said percentile, with values that were similar to those expected in the adult population. A progressive increase was observed, reaching 19 sec/arc before six years of age, with this stereoacuity value becoming more established in children from seven years of age.

CONCLUSION

Although given the specific type of sampling that was performed it was not possible to generalise the results to the entire population, these percentile curves may aid paediatric professionals in their assessment of the development of this visual ability, which is indicative of the degree of development of binocular vision.

An Evaluation of the Agreement Between a Computerized Stereoscopic Game Test and the TNO Stereoacuity Test

PURPOSE

Stereo-anomaly is commonly associated with amblyopia. An investigation was conducted to determine whether the measurements of stereoacuity obtained with the stereoacuity reference test (TNO Test) show an agreement with a computer stereoscope video game.

METHODS

Thirty-two subjects (mean age 9.37±2.00 years) with an amblyopia history were selected for a blind and randomized study of stereoacuity improvement through a new random dot game. A masked examiner measured the stereoacuity three times per subject using the TNO test (at the beginning, at the end and after 6 months of the treatment). A second masked examiner measured stereoacuity using the new computerized game after the TNO masked evaluation.

RESULTS

The Pearson's correlation coefficient one test against the other was r² = 0.767 and the Bland-Altman plot was r²= 0.069 (mean difference -0.03 log sec). Using three categories: poor (840-300 seconds of arc), coarse (480-210 seconds of arc) and moderate-fine stereoacuity (210-30 seconds of arc). Positive predictive values were 89.5% for moderate-fine; 72.7% for coarse; and 90.0% for poor stereoacuity. In addition, the agreement was evaluated using the Kappa coefficient (K= 0.743) with a 0.95 confidence interval and lower and upper Kappa limits were (0.628 and 0.858), respectively. Kappa coefficient and limits were still good when analyzing data before (K =0.663, 0.420 and 0.906) and after the treatment (K= 0.765, 0.632 and 0.899).

CONCLUSION

The Computerized Stereoscopic Game test allows the measure of stereoacuity. It can be used for both the purpose of detecting stereo vision deficits or tracking stereo vision development.

Impact of Amblyopia on Visual Attention and Visual Search in Children

Purpose

The purpose of this study was to compare binocular visual attention, visual processing speeds, and visuo-cognitive search ability in children with and without amblyopia and investigate the association of visual acuity and binocular function with these measures.

Methods

Participants included 20 children with amblyopia (mean age = 9.0 ± 1.2 years; 15 anisometropic and 5 strabismic) and 20 children with normal vision development (9.5 ± 1.7 years). Vision assessment included visual acuity (monocular and binocular) and binocular function (Worth 4 Dot and Randot Preschool Stereotest). Visual attention and processing speeds were assessed using the three subtests of the Useful Field of View (UFOV; central processing, divided attention, and selective attention). Visuo-cognitive search was measured using static and dynamic presentations of the Trail Making Tests (TMTs), parts A and B, with increasing levels of executive function demand. All children performed these tasks binocularly.

Results

Children with amblyopia demonstrated slower visual processing times on the UFOV (P = 0.04), and slower completion times on the TMT search tests (P = 0.014), compared to controls. TMT performance for children with amblyopia was also more negatively impacted with increasing executive function demands on the TMT part B, compared to controls (P = 0.005). Binocular visual acuity was associated with TMT (P = 0.006) and UFOV (P = 0.07) performance, but none of the other visual function measures were related to performance on these tasks.

Conclusions

Children with amblyopia exhibit deficits in higher-order visual processing skills, including visual attention and visual search, particularly with increasing executive function demands. These findings have implications for understanding the impact of amblyopia on everyday function in children.

Normative Values, Testability, and Validity for a New Preferential Looking Stereoacuity Test

Introduction: Age norms and testability for 3-5 year old children have been reported for the PASS III stereotest using a pointing response. We aimed to expand the normative data to children as young as 6 months, assess testability, and evaluate validity use of the PASS III as a preferential-looking test for younger children and children with special needs. Methods: 68 control children, 362 children with eye conditions, and 167 children with special needs were tested with the PASS III. Percent testable was calculated for children with and without special needs, normal tolerance limits were determined, and test validity was assessed. Results: In controls, mean PASS III stereoacuity improved from 371 arcsec at 12 months to 174 arcsec at 24 months, and 87 arcsec at 36 months. Testability in the 12, 24, and 36 months age groups were 81%, 87%, and 97% respectively and 92% for special needs children. Comparison to previously published norms and testing in a known nil stereoacuity cohort supported PASS III test validity. Compared to gold standard stereoacuity tests, accuracy of the PASS was 89%. Conclusion: Overall, preferential-looking tests using the PASS III provide a sensitive and specific measure of stereoacuity with high testability for young children and children with special needs.

Amblyopia

Amblyopia is a neurodevelopmental abnormality that results in physiological alterations in the visual pathways and impaired vision in one eye, less commonly in both. It reflects a broad range of neural, perceptual, oculomotor, and clinical abnormalities that can occur when normal visual development is disrupted early in life. Aside from refractive error, amblyopia is the most common cause of vision loss in infants and young children. It causes a constellation of perceptual deficits in the vision of the amblyopic eye, including a loss of visual acuity, position acuity, and contrast sensitivity, particularly at high spatial frequencies, as well as increased internal noise and prolonged manual and saccadic reaction times. There are also perceptual deficits in the strong eye, such as certain types of motion perception, reflecting altered neural responses and functional connectivity in visual cortex (Ho et al., 2005). Treatment in young children consists of correction of any refractive error and patching of the strong eye. Compliance with patching is challenging and a substantial proportion of amblyopic children fail to achieve normal acuity or stereopsis even after extended periods of treatment. There are a number of promising experimental treatments that may improve compliance and outcomes, such as the playing of action video games with the strong eye patched. Although there may be a sensitive period for optimal effects of treatment, there is evidence that amblyopic adults may still show some benefit of treatment. However, there is as yet no consensus on the treatment of adults with amblyopia.

Comparison of a New, Filter-Free Stereopsis Test (BEST) With the Randot Stereotest in a Pediatric Cohort

PURPOSE

To evaluate the Bernell Evaluation of Stereopsis Test (BEST) (Bernell Corporation, Mishawaka, IN), a new lenticular technology and filter-free test to measure stereopsis in children, and compare it to the Randot Stereotest (Randot) (Stereo Optical, Inc., Chicago, IL).

METHODS

This was a retrospective review of the medical records of children examined at the Center for Pediatric Ophthalmology at Hadassah-Hebrew University Medical Center from July to November 2018. All children were evaluated with the Randot and BEST in a random order.

RESULTS

The study included 100 children (53% female, 64% orthophoric) with a mean age of 8.52 ± 3.18 years (range: 3.3 to 17.8 years) and mean best corrected visual acuity of 0.178 ± 0.16 logMAR (range: 0 to 0.7 logMAR). The mean BEST stereoacuity was 1.772 ± 0.27 log seconds of arc (arcsec), whereas the mean Randot stereo-acuity was 1.778 ± 0.39 log arcsec (P = .835). The Bland- Altman analysis revealed an overall bias of 0.0073 log arcsec (95% confidence interval: 0.04219 to 0.05679 log arcsec), with limits of agreement of -0.4816 to 0.4962 log arcsec (0.3299 to 3.1347 arcsec). A significant proportional bias was noted because the difference between the tests was significantly larger in higher log arcsec values (t = 5.566, P < .001). Age, gender, strabismus, and visual acuity did not affect the differences between the stereoacuity tests (P > .05). Both tests were influenced by strabismus but not monocular amblyopia.

CONCLUSIONS

BEST stereoacuity measurements were comparable to those of the Randot, with no significant difference in crude values, minimal bias, and narrow limits of agreement. A larger, clinically insignificant variability between tests was noted with lower stereoacuity values, because children achieved better scores with the BEST. The BEST may be a valuable tool in the arsenal of the ophthalmologist. [J Pediatr Ophthalmol Strabismus. 2020;57(2):129-135.].

The prevalence and diagnosis of 'stereoblindness' in adults less than 60 years of age: a best evidence synthesis

PURPOSE

Stereoscopic vision (or stereopsis) is the ability to perceive depth from binocular disparity - the difference of viewpoints between the two eyes. Interestingly, there are large individual differences as to how well one can appreciate depth from such a cue. The total absence of stereoscopic vision, called 'stereoblindness', has been associated with negative behavioural outcomes such as poor distance estimation. Surprisingly, the prevalence of stereoblindness remains unclear, as it appears highly dependent on the way in which stereopsis is measured.

RECENT FINDINGS

This review highlights the fact that stereopsis is not a unitary construct, but rather implies different systems. The optimal conditions for measuring these varieties of stereoscopic information processing are discussed given the goal of detecting stereoblindness, using either psychophysical or clinical stereotests. In that light, we then discuss the estimates of stereoblindness prevalence of past studies.

SUMMARY

We identify four different approaches that all converge toward a prevalence of stereoblindness of 7% (median approach: 7%; unambiguous-stereoblindness-criteria approach: 7%; visual-defect-included approach: 7%; multiple-criteria approach: 7%). We note that these estimates were derived considering adults of age <60 years old. Older adults may have a higher prevalence. Finally, we make recommendations for a new ecological definition of stereoblindness and for efficient clinical methods for determining stereoblindness by adapting existing tools.

From suppression to stereoacuity: a composite binocular function score for clinical research

PURPOSE

This study aimed to validate a binocular function score that is based on common clinical measures of visual function, providing a more complete analysis of binocular outcomes, against laboratory-based dichoptic tests of threshold stereoacuity and depth of suppression.

METHODS

Scores on a composite binocular function (BF) score derived from clinical stereoacuity measures (Randot Preschool Stereoacuity Test and Randot Butterfly) and the Worth 4 Dot test were determined in adults (n = 20; age 24.8 ± 7.2 years) and children (N = 77; age 8.3 ± 1.7 years) with abnormal binocular vision from strabismus or amblyopia. Adults had threshold stereoacuity measured with a novel, computerised dichoptic psychophysical test of stereopsis. Depth of suppression (dichoptic eye chart inter-ocular contrast balance test) was determined in both adults and children.

RESULTS

Clinical Randot stereoacuity was measurable in 50% of adult and 61% of child participants. Threshold stereoacuity was measurable in 65% of the adult participants. The presence of suppression or simultaneous perception (flat fusion or diplopia) was measurable in all participants, enabling assignment of a BF score to all participants in both groups. In adults, the BF score was highly correlated with the psychophysical threshold stereoacuity measure (ρ = 0.71; p < 0.001). In both adults and children, there was also a high correlation between the BF score and inter-ocular contrast balance (adult ρ = 0.90; child ρ = 0.86; p < 0.001).

CONCLUSIONS

The composite BF score is a convenient and valid scale of binocularity that can be used to extend the stereoacuity measure in cohorts where nil stereoacuity is common and thus could be considered as an outcome measure in clinical trials.

Validation of dynamic random dot stereotests in pediatric vision screening

PURPOSE

Stereo vision tests are widely used in the clinical practice for screening amblyopia and amblyogenic conditions. According to literature, none of these tests seems to be suitable to be used alone as a simple and reliable tool. There has been a growing interest in developing new types of stereo vision tests, with sufficient sensitivity to detect amblyopia. This new generation of assessment tools should be computer based, and their reliability must be statistically warranted. The present study reports the clinical evaluation of a screening system based on random dot stereograms using a tablet as display. Specifically, a dynamic random dot stereotest with binocularly detectable Snellen-E optotype (DRDSE) was used and compared with the Lang II stereotest.

METHODS

A total of 141 children (aged 4-14, mean age 8.9) were examined in a field study at the Department of Ophthalmology, Pécs, Hungary. Inclusion criteria consisted of diagnoses of amblyopia, anisometropia, convergent strabismus, and hyperopia. Children with no ophthalmic pathologies were also enrolled as controls. All subjects went through a regular pediatric ophthalmological examination before proceeding to the DRDSE and Lang II tests.

RESULTS

DRDSE and Lang II tests were compared in terms of sensitivity and specificity for different conditions. DRDSE had a 100% sensitivity both for amblyopia (n = 11) and convergent strabismus (n = 21), as well as a 75% sensitivity for hyperopia (n = 36). However, the performance of DRDSE was not statistically significant when screening for anisometropia. On the other hand, Lang II proved to have 81.8% sensitivity for amblyopia, 80.9% for strabismus, and only 52.8% for hyperopia. The specificity of DRDSE was 61.2% for amblyopia, 67.3% for strabismus, and 68.6% for hyperopia, respectively. Conversely, Lang II showed about 10% better specificity, 73.8% for amblyopia, 79.2% for strabismus, and 77.9% for hyperopia.

CONCLUSIONS

The DRDSE test has a better sensitivity for the detection of conditions such as amblyopia or convergent strabismus compared with Lang II, although with slightly lower specificity. If the specificity could be further improved by optimization of the stimulus parameters, while keeping the sensitivity high, DRDSE would be a promising stereo vision test for screening of amblyopia.

Subnormal Binocular Contrast Sensitivity Summation in Patients with Intermittent Exotropia

BACKGROUND

To evaluate binocular summation ratio using contrast sensitivity (CS) testing and correlation between binocular summation and stereoacuity, and control scale in intermittent exotropia (IXT).

METHODS

We conducted a prospective case-control study. Thirty-seven IXT and 41 controls were evaluated with both monocular and binocular CS testing. We compared the binocular summation ratio of IXT to that of controls. Near and distance stereoacuity was assessed and office-based control scale was evaluated. We investigated correlation between binocular CS summation ratio and stereoacuity, and control scale in IXT, respectively.

RESULTS

IXT had lower binocular CS summation ratio than controls at 1.5 and 3.0 cycles/degree (1.01 ± 1.02 vs. 1.62 ± 1.88 and 1.17 ± 0.96 vs. 1.86 ± 1.75, Both P < 0.05). We found significant correlation between binocular CS summation ratio at 3.0 cycles/degree and both near and distance stereoacuity (r = -0.411, P = 0.012 and r = -0.624, P = 0.005), and ratio at 1.5 cycles/degree also correlated significantly with distance stereoacuity (r = -0.397, P = 0.034) in the IXT. Binocular CS summation ratio was correlated to control scale at 1.5 and 3.0 cycles/degree (r = -0.327, P = 0.041 and r = -0.418, P = 0.028), and the ratio significantly differed in control scale groupings analysis at the same frequencies (Both P < 0.05).

CONCLUSION

Our findings of subnormal binocular CS summation ratio in IXT had correlation with stereoacuity and control scale suggest that binocular CS testing may be a useful method in assessing binocular visual function in IXT.

Early diagnosis of amblyopia

Amblyopia can be improved or eliminated more easily when treated early in life. Because amblyopia in older children is generally less responsive to treatment (Holmes et al., 2011), there is a premium on the early identification of amblyopia and its risk factors and the subsequent treatment thereof. Clinical preference is to institute treatment in children before 7 years of age when an optimal visual outcome is typically easier to obtain.

Stereopsis results at 4.5 years of age in the infant aphakia treatment study

PURPOSE

To determine whether stereopsis of infants treated for monocular cataracts varies with the type of optical correction used.

DESIGN

Randomized prospective clinical trial.

METHODS

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.

RESULTS

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).

CONCLUSION

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.

Stereoacuity of preschool children with and without vision disorders

PURPOSE

To evaluate associations between stereoacuity and presence, type, and severity of vision disorders in Head Start preschool children and determine testability and levels of stereoacuity by age in children without vision disorders.

METHODS

Stereoacuity of children aged 3 to 5 years (n = 2898) participating in the Vision in Preschoolers (VIP) Study was evaluated using the Stereo Smile II test during a comprehensive vision examination. This test uses a two-alternative forced-choice paradigm with four stereoacuity levels (480 to 60 seconds of arc). Children were classified by the presence (n = 871) or absence (n = 2027) of VIP Study-targeted vision disorders (amblyopia, strabismus, significant refractive error, or unexplained reduced visual acuity), including type and severity. Median stereoacuity between groups and among severity levels of vision disorders was compared using Wilcoxon rank sum and Kruskal-Wallis tests. Testability and stereoacuity levels were determined for children without VIP Study-targeted disorders overall and by age.

RESULTS

Children with VIP Study-targeted vision disorders had significantly worse median stereoacuity than that of children without vision disorders (120 vs. 60 seconds of arc, p < 0.001). Children with the most severe vision disorders had worse stereoacuity than that of children with milder disorders (median 480 vs. 120 seconds of arc, p < 0.001). Among children without vision disorders, testability was 99.6% overall, increasing with age to 100% for 5-year-olds (p = 0.002). Most of the children without vision disorders (88%) had stereoacuity at the two best disparities (60 or 120 seconds of arc); the percentage increasing with age (82% for 3-, 89% for 4-, and 92% for 5-year-olds; p < 0.001).

CONCLUSIONS

The presence of any VIP Study-targeted vision disorder was associated with significantly worse stereoacuity in preschool children. Severe vision disorders were more likely associated with poorer stereopsis than milder or no vision disorders. Testability was excellent at all ages. These results support the validity of the Stereo Smile II for assessing random-dot stereoacuity in preschool children.

Stereoacuity norms for school-age children using the Frisby stereotest

BACKGROUND

The Frisby stereotest and the TNO test for stereoscopic vision are popular clinical tests for assessing stereoacuity: however, reference data for school-age children for the Frisby stereotest are limited. This study compared stereoacuity results of both tests in a large sample of typically developing school-age children.

METHODS

Primary (elementary school grades 1-6) and post-primary (high school grades 7-11) students aged 6-16 years were recruited and assessed in schools. Stereoacuity thresholds were measured using the Frisby and TNO stereotests. Children with ocular pathology, anisometropia of ≥1.00 D, interocular difference of visual acuity ≥0.2 logMAR, or strabismus were excluded.

RESULTS

A total of 212 children were recruited; data for 186 subjects were analyzed. Median Frisby stereoacuity scores were, for crossed disparity, 20 arcsec for primary and 10 arcsec for post-primary children and, for uncrossed disparity, 25 arcsec (primary) and 10 arcsec (post-primary). TNO stereoacuity was 60 arcsec for both age groups. For Frisby stereoacuity, scores of 85 arcsec (crossed) and 170 arcsec (uncrossed) or better were achieved by 95% of primary school children; scores of 85 arcsec (crossed and uncrossed) or better were achieved by 95% of post-primary subjects. A statistically significant difference in median stereoacuity scores was noted across age groups for the Frisby stereotest (crossed: z = 4.67, P < 0.0001; uncrossed: z = 4.67, P < 0.0001). No statistically significant difference in stereoacuity scores was noted with the TNO stereotest (z = 1.35, P = 0.18). A significant weak correlation was found between the Frisby and TNO stereotests (Frisby [crossed], r = 0.21 P < 0.005).

CONCLUSIONS

These data describe normative values for the Frisby stereotest for children aged 6-16 years. Participants recorded significantly better stereoacuity scores with the Frisby stereotest than the TNO stereotest. The Frisby stereotest values are weakly correlated with the TNO stereoacuity test.

Stability of near stereoacuity in childhood intermittent exotropia

PURPOSE

To investigate the course of near stereoacuity in a cohort of children with untreated intermittent exotropia.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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

PURPOSE

To determine factors associated with pretreatment and posttreatment stereoacuity in subjects with moderate anisometropic amblyopia.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

Stereoacuity thresholds before and after visual acuity testing

PURPOSE

To compare stereoacuity thresholds before and after visual acuity testing in patients with intermittent strabismus and in controls.

DESIGN

Prospective cohort study.

PARTICIPANTS AND CONTROLS

Eighty-eight patients (41 with intermittent strabismus and 47 controls) with measurable stereoacuity on their initial stereoacuity test were enrolled prospectively.

METHODS

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.

MAIN OUTCOME MEASURES

Change in stereoacuity thresholds (log seconds of arc [arcsec]).

RESULTS

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.

CONCLUSIONS

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.

FINANCIAL DISCLOSURE(S)

The author(s) have no proprietary or commercial interest in any materials discussed in this article.

The accuracy of photoscreening at detecting treatable ocular conditions in children with Down syndrome

BACKGROUND

Children with Down syndrome (DS) have an increased prevalence of ocular disorders, including amblyopia, strabismus, and refractive error. Health maintenance guidelines from the Down Syndrome Medical Interest Group recommend ophthalmologic examinations every 1 to 2 years for these children. Photoscreening may be a cost-effective option for subsequent screening evaluations after an initial complete examination, but no study has evaluated the accuracy of photoscreening in children with DS. The purpose of this study is to determine the sensitivity, specificity, and positive and negative predictive values of photoscreening in detecting treatable ocular conditions in children with DS.

METHODS

Photoscreening and complete ophthalmologic evaluations were performed in 50 consecutive 3- to 10-year-old children with DS. Sensitivity, specificity, and positive and negative predictive values were calculated with the use of ophthalmologic examination findings as the reference standard.

RESULTS

Most children were able to complete photoscreening (94% with Medical Technology and Innovations [MTI] and 90% with Visiscreen OSS-C [VR]). Many children had an identified diagnosis on ophthalmologic examination (n = 46, 92%). Of these, approximately one-half (n = 27, 54%) had one or more condition(s) requiring treatment. Both the MTI and VR photoscreening devices had a sensitivity of 93% (95% confidence interval 0.76-0.99) for detecting treatable ocular conditions. The specificities for the MTI and VR photoscreening were 0.35 (0.18-0.57) and 0.55 (0.34-0.74), respectively.

CONCLUSIONS

Photoscreening is sensitive but less specific at detecting treatable ocular conditions in children with DS. In specific instances, the use of photoscreening in the DS population has the potential to save time and expense related to routine eye examinations, particularly in children with a normal baseline comprehensive examination.

Final version of the Distance Randot Stereotest: normative data, reliability, and validity

PURPOSE

Measurement of distance stereoacuity may be useful in assessing strabismic patients, especially those with intermittent exotropia. We developed the Distance Randot Stereotest as an easily administered quantitative test for distance stereoacuity in children. By using a prototype, we reported testability, validity, and normative data. Here we report normative and validity data for the final, commercially available version of the test.

METHOD

We administered both the Prototype and the Final Version Distance Randot Stereotest to 156 normal volunteers (2-40 years of age) and 77 strabismic patients (4-62 years of age). Test-retest data were collected for the Final Version.

RESULTS

Normative Final Version scores were similar to those obtained with the Prototype; 96% were < or = 100 arcsec. Test-retests were identical in 82% and within one disparity level in 100%. Final Version scores were correlated with Prototype scores (rs = 0.64, p < 0.001). Among strabismic patients, 62.3% had abnormal stereoacuity; those with normal scores had incomitant or intermittent deviations. Nil stereoacuity was found in 27 patients, confirmed in 90.9% of retests; 17 had measurable stereoacuity, confirmed in 96.3% of retests. Patients with constant strabismus were more likely to have nil stereoacuity than patients who had intermittent strabismus (95% vs 12.2%).

CONCLUSIONS

Distance Randot scores from normal subjects have low variability within each age group and high test-retest reliability. There is little overlap between Distance Randot scores from normal control and strabismic patients. The Distance Randot Stereotest is a sensitive measurement of binocular sensory status that may be useful in monitoring progression of strabismus and/or recovery after strabismus surgery.

The teller acuity cards are effective in detecting amblyopia

PURPOSE

Detection of amblyopia in infants and toddlers is difficult because the current clinical standard for this age group, fixation preference, is inaccurate. Although grating acuity represents an alternative, studies of preschoolers and schoolchildren report that it is not equivalent to the gold standard optotype acuity. Here, we examine whether the Teller Acuity Cards (TAC) can detect amblyopia effectively by testing children old enough (7.8 +/- 3.6 years) to complete optotype acuity testing.

METHODS

Grating acuity was assessed monocularly in 45 patients with unilateral amblyopia, 44 patients at risk for amblyopia, and 37 children with no known vision disorders. Each child's grating acuity was classified as normal/abnormal based on age-appropriate norms. These classifications were compared with formal amblyopia diagnoses.

RESULTS

Grating acuity was finer than optotype acuity among amblyopic eyes (medians: 0.28 vs. 0.40 logMAR, respectively, p < 0.0001) but not among fellow eyes (medians: 0.03 vs. 0.10 logMAR, respectively, p = 0.36). The optotype acuity-grating acuity discrepancy among amblyopic eyes was larger for cases of severe amblyopia than for moderate amblyopia (means: 0.64 vs. 0.18 logMAR, respectively, p = 0.0001). Nevertheless, most cases of amblyopia were detected successfully by the TAC, yielding a sensitivity of 80%. Furthermore, grating acuity was relatively sensitive to all amblyopia subtypes (69 to 89%) and levels of severity (79 to 83%).

CONCLUSIONS

Although grating acuity is finer than optotype acuity in amblyopic eyes, most children with amblyopia were identified correctly suggesting that grating acuity is an effective clinical alternative for detecting amblyopia.

Testability of vision and refraction in preschoolers: the strabismus, amblyopia, and refractive error study in singaporean children

PURPOSE

To determine the testability of several vision and refraction tests in preschool-aged children.

DESIGN

Population-based study of Chinese preschool-aged children in Singapore.

METHODS

One thousand five hundred and forty-two Singaporean Chinese children aged 6 to 72 months were recruited through door-to-door screening of government-subsidized apartments in Singapore. Trained eye professionals administered all tests, including monocular logarithm of the minimum angle of resolution visual acuity with the Sheridan Gardiner chart, monocular Ishihara color testing (Richmond Products Inc, Albuquerque, New Mexico, USA), biometric measurements using IOLMaster (Carl Zeiss, Jena, Germany), and Randot stereoacuity (Stereo Optical Co, Chicago, Illinois, USA) for children 30 to younger than 72 months. Cycloplegic refraction and keratometry measurements also were determined using a table-mounted autorefractor (Canon Autorefractor RK-F1; Canon, Tokyo, Japan) in children 24 to younger than 72 months.

RESULTS

Testabilities were 84.8% for visual acuity (40.7% for age 30 to < 36 months, 70.8% for age 36 to < 42 months, 86.7% for age 42 to < 48 months, 94.8 for age 48 to < 54 months, 98.6 for age 54 to < 66 months, and 98.7% for age 66 to < 72 months), 81.1% for the Ishihara color test, 82.2% for Randot stereoacuity, 62.2% for table mounted autorefraction, and 91.7% for IOLMaster. All testabilities significantly increased with age (P < .0001). Girls had higher testability rates than boys for the autorefraction and Randot stereoacuity tests (P = .036 and .008, respectively).

CONCLUSIONS

The vision and refraction tests were testable in a high proportion of preschool-aged Chinese Singaporeans. Preschool children in older age groups are likely to complete these tests successfully, with important implications for determining age limits for screening in the community and clinic.

Stereoacuity outcomes after treatment of infantile and accommodative esotropia

PURPOSE

To review what is known about the normal maturation of stereoacuity, the stereoacuity deficits associated with infantile and accommodative esotropia, the rationale for making improved stereoacuity a goal of treatment, and strategies for improving stereoacuity outcomes.

METHODS

Studies of stereoacuity maturation during normal development, studies of stereoacuity outcomes after treatment for infantile and accommodative esotropia, and studies of primate models of esotropia are reviewed.

RESULTS

Stereoacuity maturation normally proceeds rapidly during the first year of life. Infantile and accommodative esotropia are associated with profound and permanent disruption of stereopsis. Although rehabilitation of stereoacuity after treatment of esotropia remains a challenge, even the achievement of subnormal stereoacuity may have real benefits to the child.

CONCLUSIONS

Some abnormalities in stereoacuity may exist before the onset of esotropia, but others may result directly from abnormal binocular experience. Several strategies for improving stereoacuity outcomes in esotropia are currently under active investigation. Improved stereoacuity outcomes are associated with better long-term stability of alignment, reduced risk for and severity of amblyopia, improved achievement of sensorimotor developmental milestones, better reading ability, and improved long-term quality of life.

Effect of amblyopia on self-esteem in children

PURPOSE

In an investigation of the psychosocial impact of amblyopia on children, the perceived self-esteem of children who had been treated for amblyopia was compared with that of age-matched controls. The influence of amblyopia condition or treatment factors that may impact self-perception scores was also explored.

METHODS

Children with a history of treatment for amblyopia (n = 47; age 9.2 +/- 1.3 years) and age-matched controls (n = 52; age 9.4 +/- 0.5 years) completed a standardized age-appropriate questionnaire based evaluation of perceived self-esteem (Harter Self Perception Profile for Children). Their vision characteristics and treatment regimen were also recorded. Bivariate correlation analysis was used to investigate the amblyopic characteristics and treatment factors that may have influenced self-perception scores in the amblyopic group.

RESULTS

Children treated for amblyopia had significantly lower social acceptance scores than age-matched control children. In other areas related to self-esteem, including scholastic competence, physical appearance, athletic competence, behavioral conduct and global self worth, amblyopic children gave scores similar to those of control children. Within the amblyopic group, a lower social acceptance score was significantly correlated with a history of treatment with patching but not with a history of strabismus or wearing of glasses.

CONCLUSIONS

Self-perception of social acceptance was lower in children treated for amblyopia compared with age-matched controls. A reduction in these scores was associated with a history of patching treatment but not with a history of strabismus or spectacle wear.

Defining real change in measures of stereoacuity

PURPOSE

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.

DESIGN

Retrospective cohort study.

PARTICIPANTS AND CONTROLS

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.

METHODS

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.

MAIN OUTCOME MEASURES

The 95% limits of agreement for change in stereoacuity thresholds at 2 consecutive visits.

RESULTS

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.

CONCLUSIONS

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.

FINANCIAL DISCLOSURE(S)

The authors have no proprietary or commercial interest in any materials discussed in this article.

Improvement in distance stereoacuity following surgery for intermittent exotropia

PURPOSE

To evaluate whether distance stereoacuity improves following surgery for intermittent exotropia using the Frisby Davis Distance (FD2) and Distance Randot stereotests.

METHODS

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).

RESULTS

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).

CONCLUSIONS

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.

Variability of stereoacuity in intermittent exotropia

PURPOSE

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.

DESIGN

Prospective cohort study.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

Changes in visual function following optical treatment of astigmatism-related amblyopia

Effects of optical correction on best-corrected grating acuity (vertical (V), horizontal (H), oblique (O)), vernier acuity (V, H, O), contrast sensitivity (1.5, 6.0, and 18.0 cy/deg spatial frequency, V and H), and stereoacuity were evaluated prospectively in 4- to 13-year-old astigmats and a non-astigmatic age-matched control group. Measurements made at baseline (eyeglasses dispensed for astigmats), 6 weeks, and 1 year showed greater improvement in astigmatic than non-astigmatic children for all measures. Treatment effects occurred by 6 weeks, and did not differ by cohort (<8 vs. >or= 8 years), but astigmatic children did not attain normal levels of visual function.

Randot Preschool Stereoacuity Test: normative data and validity

INTRODUCTION

The Randot Preschool Stereoacuity Test is a widely used three-book test for the assessment of binocular status. Using a prototype, we previously reported high testability in children as young as 3 years, validity data, and some normative data. Here we report extensive normative and validity data for the final version of the test. In addition, we report normative data for a new, fourth book that adds finer disparities.

METHODS

The Randot Preschool Stereoacuity Test was administered to 4355 normal children aged 3 to 18 years and 39 adults in multiple settings. In addition, the Randot Preschool Stereoacuity Test along with the new, fourth book that added 30 arcsec and 20 arcsec disparity levels was administered to 1402 normal children aged 3 to 18 years and 33 normal adults. Both the four-book Randot((R)) Preschool Stereoacuity Test and the Randot circles were administered to 242 patients with amblyogenic conditions aged 3 to 18 years.

RESULTS

Mean normal stereoacuity improved from 100 arcsec at 3 years of age to 60 arcsec by 5 years and 40 arcsec by 7 years. The lower limit of normal was 400 arcsec at 3 years, 200 arcsec at 4 years, and 60 arcsec at 7 years. Using the new four-book version, further improvement in mean stereoacuity could be appreciated beyond 7 years of age to 30 arcsec in the 11- to 18-year-old and adult groups. Among the 242 patients, Randot Preschool Stereoacuity Test stereoacuity was strongly associated with Randot circle stereoacuity (chi(2) = 261.0, p < 0.001).

CONCLUSIONS

Normative data for the Randot Preschool Stereoacuity Test show a monotonic improvement of stereoacuity from age 3 years through the teen years. Patient data support the validity of the Randot Preschool Stereoacuity Test.

New tests of distance stereoacuity and their role in evaluating intermittent exotropia

PURPOSE

Poor control of intermittent exotropia has been considered an indication for surgical intervention, and poor distance stereoacuity may be an indicator of poor control. Two new measures of distance stereoacuity, the Frisby-Davis Distance test (FD2) and Distance Randot test (DR), both of which have been validated in normal and strabismic subjects, were evaluated, and we compared stereoacuity with scores on a recently described control scale.

DESIGN

Prospective case series.

PARTICIPANTS

Twenty-five consecutive patients with intermittent exotropia.

METHODS

Office-based control was graded at distance and near on a 0 to 5 scale, and distance control ranged from 1 (recovery in 1-5 seconds after monocular occlusion) to 4 (>50% spontaneously tropic). Stereoacuity was measured using the FD2 and DR at distance and the Preschool Randot and Frisby tests at near.

MAIN OUTCOME MEASURE

Distance stereoacuity measured using the FD2 and DR.

RESULTS

Measurable distance stereoacuity thresholds in intermittent exotropia were poor with the DR and excellent with the FD2 (medians, nil and 40''; P<0.0001). Near stereoacuity was excellent with both the Preschool Randot and Frisby (medians, 60'' and 60''; P = 0.99). There was poor correlation between distance control score and either FD2 (r(s) = 0.1, P = 0.6) or DR (r(s) = 0.3, P = 0.2). Control scores correlated with magnitude of deviation at distance (r(s) = 0.5, P = 0.02) and near (r(s) = 0.5, P = 0.01).

CONCLUSIONS

The real-world contour-based targets of the new distance FD2 appear to stimulate fusion in intermittent exotropia, even when distance control is poor. In contrast, the new Polaroid vectograph-based DR is very sensitive to disturbances of binocularity. Two new distance stereoacuity tests appear sensitive to opposite ends of the intermittent exotropia spectrum; FD2 performance deteriorates when the patient is constantly tropic, whereas DR performance deteriorates at the earliest stages of intermittency.

Amblyopia in astigmatic children: patterns of deficits

Neural changes that result from disruption of normal visual experience during development are termed amblyopia. To characterize visual deficits specific to astigmatism-related amblyopia, we compared best-corrected visual performance in 330 astigmatic and 475 non-astigmatic kindergarten through 6th grade children. Astigmatism was associated with deficits in letter, grating and vernier acuity, high and middle spatial frequency contrast sensitivity, and stereoacuity. Although grating acuity, vernier acuity, and contrast sensitivity were reduced across stimulus orientation, astigmats demonstrated orientation-dependent deficits (meridional amblyopia) only for grating acuity. Astigmatic children are at risk for deficits across a range of visual functions.

Assessment of a new Distance Randot stereoacuity test

PURPOSE

We sought to develop a new "Distance Randot" test, establish a normative data set for children and adults, and compare with established measures of stereoacuity.

METHODS

Distance Randot, distance Frisby-Davis 2 (FD2), and near Preschool Randot stereoacuity (Stereo Optical Co., Inc., Chicago, IL) were assessed in 23 normal children (ages 4-14 years), 21 normal adults (ages 20-36 years), and 131 patients with a variety of strabismic conditions (ages 4-85 years). For each test, stereoacuity was defined as the smallest disparity in which 2 targets were correctly identified. The simultaneous prism and cover test (SPCT) and the alternate prism and cover test (APCT) were used to assess misalignment.

RESULTS

For the new Distance Randot test, normative results were similar to published data obtained with established near and distance stereoacuity tests. In the patient cohort, comparing stereoacuity data obtained from Distance Randot stereoacuity test and the Near Preschool Randot stereoacuity test, most of the patients with discordant scores had poorer distance than near stereoacuity. Comparing the Distance Randot stereoacuity test and the Distance FD2, all of the patients with discordant scores had poorer Distance Randot than FD2 scores.

CONCLUSIONS

Distance Randot test is more likely to detect abnormalities in distance stereopsis and may provide a useful tool in measuring distance stereoacuity in patients with and without strabismus. However, further studies are needed to define the efficacy of the Distance Randot test in monitoring progression specific conditions such as intermittent exotropia, where it may prove useful as a guide to the timing of intervention.

Real depth vs randot stereotests

PURPOSE

To compare the performance of real depth and Randot stereotests in strabismic and nonstrabismic patients.

DESIGN

Observational case series.

METHODS

Stereoacuity was tested in 182 patients with a variety of strabismic conditions, using the Frisby-Davis 2 (FD2) distance stereotest, the near Frisby (nF) (both real depth tests), the Preschool Randot (nR), and Distance Randot (dR) tests (both based on Polaroid vectographs).

RESULTS

Patients appreciated finer disparities with the nF test than the nR test at near and with the FD2 test than the dR test at distance.

CONCLUSIONS

The type of stereotest influences measurable thresholds, and the results from different tests are not interchangeable. The choice of test should depend on the question being asked; nF and FD2 would be appropriate for determining presence or absence of stereopsis and best measurable stereopsis. The more rigorous Randot tests would be appropriate for determining subtle changes.

Long-term motor and sensory outcomes after early surgery for infantile esotropia

PURPOSE

The proper timing of surgery for infantile esotropia remains controversial. Early surgery may yield better sensory outcomes whereas later surgery may result in better alignment. Several recent studies reported promising sensory outcomes in small groups of children that underwent surgery by 6 months of age. Here, we present motor and sensory outcomes of a cohort of 50 consecutive children enrolled in a prospective study who had surgery by 6 months of age and were followed for 4-17 years.

METHODS

Angle of deviation, subsequent surgeries, treatment with spectacles, amblyopia, fusion, and stereopsis were evaluated during follow-up. Outcomes from the early surgery group were compared with a concurrently recruited cohort who had surgery at 7-12 months (n=78).

RESULTS

On the initial visit, both cohorts had the same median angle of deviation (45(Delta)) and similar refractive error; the median angle of deviation increased by the final preop visit (55(Delta)). Postoperatively, both cohorts had alignment within 6(Delta) in 83-94% of cases on all visits. Both cohorts had similar rates of additional surgery, and 44-48% wore hyperopic correction postoperatively. Compared with the 7- to 12-month cohort, more children in the early-surgery cohort had peripheral fusion (78% vs 61%; p < 0.02), central fusion (15% vs 2%; p < 0.01), Randot stereopsis (38% vs 16%; p < 0.003), and Randot stereoacuity of 200 seconds or better (20% vs 9%; p < 0.05).

CONCLUSIONS

Early surgery was associated with a higher prevalence of fusion and stereopsis, without adverse motor outcomes.

Accuracy of the Lang II stereotest in screening for binocular disorders in 6-year-old children

PURPOSE

To assess the accuracy of the Lang II stereotest in screening for strabismus, amblyopia, and anisometropia in 6-year-old children.

DESIGN

Cross-sectional population-based study.

METHODS

The Sydney Myopia Study examined 1765 6-year-old children (78.9% of eligible) who were identified by random cluster sampling of 34 schools in Sydney, Australia. Sensitivity and specificity of the Lang II stereotest was determined by best stereoacuity. Cycloplegic autorefraction, assessment of visual acuity, and ocular motility were conducted.

RESULTS

Test sensitivity ranged from 21.4% for anisometropia (> or =1.0 diopter) to 31.3% for amblyopia. The detection rate for new cases of amblyopia ranged from 20% to 40%; the detection rate for new cases of strabismus was 30%. Specificity was >98% in all three conditions. Children with false-negative results included newly diagnosed cases of strabismus (14 of 25 children) or amblyopia (5 of 12 children).

CONCLUSION

The Lang II stereotest, when used alone, has very limited value as a screening test of binocular dysfunction.

Change of stereoacuity with aging in normal eyes

PURPOSE

Stereopsis in normal subjects aged between 7 and 76 years was compared to examine changes in stereopsis with age.

METHODS

Eighty subjects with no ocular disease were divided into 8 groups by age. Near stereopsis was evaluated with the TNO, Titmus, and Randot tests; distance stereopsis with the Mentor B-VAT II video acuity tester.

RESULTS

The results of all 4 tests showed decreased stereopsis with increasing age (p<0.05). Compared to the stereoacuity of 7 to 10-year-old group, both the TNO and distance stereopsis test results were significantly decreased for the 6th, 7th, and 8th decade groups, while both the Titmus and Randot test results were significantly decreased for the 8th decade group (p<0.05).

CONCLUSIONS

Overall, both near and distance stereopsis decreased with increasing age. Thus, decreased stereopsis should be taken into account when performing the stereopsis test.

A study on the clinical usefulness of digitalized random-dot stereoacuity test

Existing methods of stereoacuity testing need specific glasses or optical device for use. We have designed a new stereoacuity test for the digitalized, random-dot stereogram and researched its clinical usefulness. A digitalized, random-dot, stereoacuity test card was created with a computer program that used a preferred symbol and the designed system was tested along with the Randot preschool stereoacuity, Titmus-fly and Lang tests to compare their sensitivity and specificity. The mean success rate of the digitalized, random-dot test was 98.2%, while the rates of the Randot preschool stereoacuity, Titmus-fly and Lang tests were 89.3%, 74.2% and 86.1%, respectively. Sensitivity and specificity of the new test were 100% and 95.3%, respectively, which were not that different from those of the Randot preschool stereoacuity, Titmus-fly and Lang tests. We found that the digitalized, random-dot, stereoacuity test has a high success rate and can be appropriately used in medical examinations and follow-up tests for strabismus patients.

Measurement of stereoacuity outcomes at ages 1 to 24 months: Randot Stereocards

PURPOSE

The aim of the present study was to develop a simple, quick, and portable random dot stereoacuity test for measurement of binocular sensory outcomes during the first 24 months of life.

METHODS

Vertical bar random dot vectographs were adapted for presentation in a "Teller Acuity Card" format, called the "Randot Stereocards." A forced-choice preferential looking protocol was used. Study participants included 386 healthy, term infants and children (normative cohort; age range: 1 month to 8 years) and 280 patients with common pediatric ophthalmic disorders (patient cohort; age range: 5 months to 9 years).

RESULTS

Overall, the success rate for test completion in the normative cohort was 91.3%. By 4 months of age, normal infants' mean stereoacuity was about 600'' and, by 6 months, 200''. Mean stereoacuity further improved to about 100'' by 12 months and 70'' by 18 months. Normative results were similar to published data obtained with laboratory-based stereoacuity tests. Randot Stereocard data from normal children aged 2 to 6 years were similar to published normative data for the Preschool Randot Stereoacuity Test. In the patient cohort, concordance between the Randot Stereocards and the Preschool Randot Test was 87%; concordance between the Randot Stereocards and the Randot Test was 84%.

CONCLUSION

The Randot Stereocards provide a simple, reliable, and valid method of obtaining a quantitative assessment of binocular vision in children up to 24 months of age for use in clinical trials and in clinical management.

Testing distance stereoacuity with the Frisby-Davis 2 (FD2) test

PURPOSE

To develop a presentation protocol for the new Frisby-Davis 2 (FD2) distance stereoacuity test.

DESIGN

Prospective data collection.

METHODS

Stereoacuity was tested monocularly and binocularly in 95 patients with a variety of strabismic and nonstrabismic conditions, using the FD2, employing a modified staircase procedure. The Preschool Randot Stereoacuity test and the near Frisby test were used to determine whether a patient was stereoblind.

RESULTS

Under monocular conditions, 35 (37%) of 95 patients passed at least the largest disparity of the FD2 indicating a problem with monocular cues. The binocular protocol was then modified to include a monocular test phase. Using the new protocol, if a patient could achieve the same stereoacuity under monocular and binocular conditions, they were deemed to have no stereopsis. Testing 28 additional stereoblind patients using the new modified protocol revealed no false positives.

CONCLUSION

The FD2 stereotest is a useful measure of distance stereoacuity, provided the presentation protocol accounts for monocular cues.

Maximum angle of horizontal strabismus consistent with true stereopsis

BACKGROUND

We prospectively evaluated the performance of three stereoacuity tests in patients with a wide range of strabismus angles to determine the maximum angle of horizontal strabismus consistent with true stereopsis as well as the extent of false-positive results.

METHODS

Subjects age > or = 5 years old (n = 186) with constant horizontal strabismus were prospectively studied. Stereoacuity was measured using the Titmus Fly, Animals, and Circles tests; the original Preschool Randot test; and the Frisby test. We defined a false-positive result as any positive response to a stereoacuity test when a patient had > 20 prism diopters (PD) of deviation. Based on the results from our previous study of monocularly patched adults, we then defined a true-positive result as Titmus circles five to nine, at least 400" on the original Preschool Randot test, or a pass on the Frisby test. Data were then analyzed to determine a maximum deviation consistent with true stereopsis.

RESULTS

False-positive results occurred with Titmus Fly (6%), Titmus Animals (10%), Titmus Circles (35%), and the 800 seconds of arc (") level of the original Preschool Randot test (10%). No false-positive results were seen with the Frisby test. Applying the criteria for a true-positive result, we found that no patient with > 10 PD of deviation had true stereopsis. The two patients with 10 PD and 6 PD deviations could not subsequently pass the Frisby test and were therefore deemed not to have true stereopsis. We concluded that the threshold for true stereopsis may be as low as 4 PD of horizontal deviation.

CONCLUSION

In summary, the Titmus Fly, Titmus Animals, and Titmus Circles (the first four circles) tests possess monocular clues that limit their usefulness for clinical testing. The Frisby test is particularly useful for rapid assessment of whether stereopsis is present or absent. The new Preschool Randot test is valuable for quantifying stereopsis in both children and adults. True stereopsis may be rare when a patient has a horizontal deviation > 4 PD.

Testability of preschoolers on stereotests used to screen vision disorders

OBJECTIVE

The purpose was to determine whether preschool children aged 3 years 0 months through 3 years 6 months could be tested with the Random Dot E, Stereo Smile, and Randot Preschool stereoacuity tests, which are random dot stereotests marketed for use with preschoolers.

METHODS

A total of 118 children from five Vision In Preschoolers Study Clinical Centers participated. Strabismic children, as determined by the cover test at distance and near, were excluded from this study. Stereopsis was tested on each child using each of the three tests in a variable, balanced order. A child's testability for each test was determined by the ability to complete the nonstereo task (pretest) and the gross stereo task for each stereotest. Proportions of children able to perform each test were compared using statistical methods accommodating multiple measurements per child.

RESULTS

Testability of children on the pretest was greater for the Stereo Smile test (91%) than for the Random Dot E test (81%; p = 0.007) or the Randot Preschool test (71%; p < 0.0001) and greater for the Random Dot E test than for the Randot Preschool test (p = 0.02). For all children, testability on the gross stereo task was greater for the Stereo Smile (77%; p < 0.0001) and Random Dot E (74%; p = 0.005) tests than for the Randot Preschool test (56%) but did not differ significantly between the Stereo Smile and Random Dot E tests (p = 0.19). There were no significant differences among the proportion of children able to complete the gross stereo task among those who were testable on the pretest (p > 0.12, all comparisons).

CONCLUSIONS

Among preschoolers aged 3 years 0 months through 3 years 6 months, testability differs significantly across the three commercially available random dot stereotests evaluated. The results suggest that two-choice procedures increase testability of young preschoolers.