Validity of the Titmus and Randot circles tasks in children with known binocular vision disorders.

PURPOSE: The Titmus and Randot (version 2) circles tests contain monocular form cues that may enable patients with binocular vision disorders to pass without any measurable stereopsis. The purpose of this study was to evaluate the validity of the Randot and Titmus circles tests for quantifying stereoacuity in children with known binocular vision disorders. METHODS: Participants included 170 consecutive children with diverse binocular sensory function ranging from fine to no measurable stereopsis. Stereoacuity was measured using the Randot circles, the Titmus circles, and the Randot Preschool Stereoacuity tests. RESULTS: Discrepancies between stereoacuity scores derived using either the Titmus or Randot circles tests and the Randot Preschool Stereoacuity test increased as a function of random-dot stereoacuity. Stereoacuity scores derived using the circles tests showed good agreement with random-dot stereoacuity when stereoacuity was 2.2 log seconds of arc (160 seconds of arc) or better, but they progressively overestimated stereoacuity for poorer random-dot stereoacuity scores. CONCLUSION: When measuring stereoacuity using either the Titmus or Randot circles tests in patients with known binocular vision disorders, stereoacuity scores > 2.2 log seconds of arc should be interpreted with caution because it is above this level of stereoacuity that the monocular form cues of each of the tests may invalidate the results.     

An Evaluation of the Agreement Between Contour-Based Circles and Random Dot-Based Near Stereoacuity Tests

INTRODUCTION: Monocular cues are present in the contour-based Titmus and Randot circles stereoacuity tests frequently giving rise to false-positive results in patients with abnormal stereoacuity. Stereoacuity derived using these 2 test types was compared to evaluate whether discrepancies between these tests were limited to the coarse/nil end of the stereoacuity spectrum or whether they were apparent across a wider range of possible stereoacuity scores, including levels of stereopsis equated with macular fusion. METHODS: Fifty-four normal volunteers and 91 patients with a history of anomalous binocular vision by a variety of conditions (eg, strabismus, monovision, or unilateral eye disease) participated. In each participant, stereoacuity was measured using the Titmus(c) circles, the Randot(c) (version 2) circles, and the Preschool Randot(c) Stereoacuity test. RESULTS: In patients with a history of anomalous binocular vision, better stereoacuity scores were acquired using the circles tests than the random dot-based Preschool Randot Stereoacuity test (Friedman repeated-measures analysis of variance on ranks, Chi-square = 99.3, P < 0.001; Student-Newman-Keuls Method, P < 0.05). Among patients with known binocular vision anomalies, stereoacuity score disagreement was evident across the entire range of measurable stereoacuity. CONCLUSIONS: Stereoacuity score discrepancies between the circles tests and the random dot based tests frequently cross categories (eg, fine vs. moderate or coarse stereopsis). Disagreement between the test types may reflect different underlying mechanisms by the different types of tests or confounding nonstereoscopic binocular cues in the Titmus and Randot circles test.     

Predictive factors underlying the restoration of macular binocular vision in adults with acquired strabismus.

PURPOSE: To investigate whether macular binocular vision can be permanently lost following acquired strabismus and to identify predictive factors underlying its restoration. SUBJECTS AND METHODS: Twenty-three patients with strabismus acquired after binocular vision maturation were enrolled. Factors studied included duration of eye misalignment, age at treatment, pre-surgical strabismus type, pre-surgical diplopia, and pre-surgical capacity for binocularity. The restoration of macular binocular vision was evaluated between 1 and 3 years following successful eye re-alignment and was defined as 60 seconds of arc stereopsis or better on the Titmus circles and/or the Preschool Randot Stereoacuity test. RESULTS: Sixteen of 23 (70%) or 7/23 (30%) of patients achieved macular binocular vision following successful surgical eye realignment using the Titmus circles versus the Preschool Randot Stereoacuity test. Patients with < or =12 months constant eye misalignment were more likely to achieve macular binocular vision following treatment than patients with >12 months constant eye misalignment. CONCLUSIONS: Macular binocular vision continues to be susceptible to permanent loss in adult patients. Factors that are predictive of the restoration of macular binocular vision include duration of constant eye misalignment and the pre-surgical capacity for binocularity.     

Interobserver test-retest reliability of the randot preschool stereoacuity test

PURPOSE: Random dot stereoacuity can be quantified to between 40 and 800 seconds of arc in preschool children by using the Randot Preschool Stereoacuity test (Stereo Optical Co, Inc, Chicago, Ill). To incorporate this test into clinic and research settings, the reliability of its stereoacuity scores obtained by separate examiners needs to be evaluated. The purpose of this study was to evaluate its interobserver test-retest reliability. METHODS: Participants included 102 consecutive children with binocular sensory function ranging from fine to no measurable stereopsis. Clinical research participants included children with anomalous binocular vision caused by strabismus, cataracts, anisometropia, and ptosis. In a prospective study, random dot stereoacuity was measured twice under masked testing conditions by 2 examiners within a 1-hour period. RESULTS: Interobserver test-retest reliability of the Randot Preschool Stereoacuity test is high among a population of children with diverse binocular sensory function. The correlation coefficient between individual test scores was highly significant (r = 0.97, P<.001). Mean differences between the 2 scores (0.021 log seconds of arc) were not significantly different from zero (t(99) = 1.33, P>.1). The upper and lower limits of agreement were narrow, reflecting both the large sample size and the small variation between the 2 test scores. Interobserver test-retest reliability of the Randot Preschool Stereoacuity test was nearly constant across levels of functional stereoacuity, patient categorization, and age at the time of the test. CONCLUSIONS: The high agreement between the Randot Preschool Stereoacuity test scores by 2 independent observers supports its use in clinical management and research settings for the quantitative assessment of binocular sensory vision, as well as in multicentered research studies.     

Stereoacuity and foveal fusion in adults with long-standing surgical monovision

PURPOSE: Although binocular vision deficits occur in children who have a constant esotropia onset following significant maturation of stereopsis, it is uncertain whether adults are susceptible to changes to binocular vision. We examined binocular vision in adults with longstanding surgical monovision (> or =6 month's duration) to determine whether the binocular visual system remains susceptible to change. METHODS: Participants included 32 adults with longstanding monovision through laser-assisted in situ keratectomy or photorefractive keratectomy and 20 age-matched control subjects. After full binocular correction, binocular function was measured by using the Randot Stereoacuity Test, the Randot Preschool Stereoacuity Test, and the Worth 4-dot test at near and distance. Monovision patients were grouped as having low anisometropia (<1.5 spherical D) or moderate anisometropia (> or =1.5 spherical D). RESULTS: Non-parametric analysis of variance revealed a significant difference between group median stereoacuity (H = 16.062; P <.001). Pairwise multiple comparisons indicated both groups with monovision had significantly worse stereoacuity compared with control subjects (P <.05). Median stereoacuity values were 100 seconds of arc for patients with low anisometropia, 150 seconds of arc for patients with moderate anisometropia, and 40 seconds of arc for control subjects. A larger proportion of patients with moderate anisometropia failed the Worth-4 dot test at distance than control subjects (z = 2.619; P =.009). CONCLUSIONS: Reduced stereoacuity and an absence of foveal fusion in adults with longstanding surgical monovision suggest continued susceptibility of the binocular visual system to anomalous binocular experience.     

随机点立体图与图形立体图检测立体视的一致性分析

目的:研究随机点立体图与图形立体图检测立体视锐度的一致性,评估偏差仅限于周边立体视或无立体视范围,还是包括黄斑中心凹立体视的整个立体视谱。方法:对4~25岁双眼视正常组76例及共同性斜视组89例,采用TNO及Randot立体图于40cm处检查近距离立体视,比较两种方法测得的立体视锐度的一致性。结果:双眼视正常组两种方法测得的立体视锐度分布无统计学差异;斜视组两种方法检测的立体视锐度分布有显著统计学差异(χ2=19.27,P<0.01),且差异存在于整个立体视谱。结论:随机点及图形立体图检查结果的不一致反应了两类方法的机制不同,图形立体图检查混杂了单眼信息导致的假阳性结果,随机点立体图检查无立体视可能并非大脑皮质立体视觉真正丧失。     

Randot stereoacuity norms in a population of Saudi Arabian children

Background : The onset and development of stereoacuity in children have been investigated by several authors. In addition to the study of those aspects of stereopsis, it is also important to collect normative data, which can be applied in the clinical setting. The purpose of this study was to establish Randot stereoacuity norms using a Saudi Arabian children population. Method : The Randot stereo test was used to measure stereoacuity for 791 male primary school children (aged six to 12 years) with normal vision. A battery of tests was used to establish that each child had normal eyes and vision prior to the stereoacuity measurement. Results : The range of stereoacuities for all the age groups at 40 cm was 70 to 20 seconds of arc, except for the nine-year-old children in whom the range was 50 to 20 seconds of arc. More than one half (57.5 per cent) of the children achieved 29 seconds of arc. The mean stereoacuity for all of the children was 25.32 seconds of arc with a standard deviation of 9.93 seconds of arc. The mean stereoacuity for the children decreased from 29.11 seconds of arc at six years to 23.61 seconds of arc at 11 years. An inter-subject variation in stereoacuity development was observed.     

Randot stereoacuity does not accurately predict ability to perform two practical tests of depth perception at a near distance.

PURPOSE: It is common practice to administer stereopsis tests such as the Randot Stereotest to prospective employees for occupations requiring depth perception. However, there is no evidence that stereoacuity measured with tests such as the Randot Stereotest will predict an individual's ability to perform a depth perception task at near. METHODS: Forty-eight people with normal binocular vision were tested on 2 practical depth perception tests, and their stereoacuity was measured with the Randot Stereotest. RESULTS: There was little correlation between stereoacuity and either of the practical tasks (r<+/-0.1). CONCLUSIONS: These results show that Randot stereoacuity does not reliably predict depth perception ability for people who enjoy normal binocular vision. A better method for determining depth perception ability might be to issue a practical depth perception task.     

Factors Affecting Improvement of Stereopsis Following Successful Surgical Correction of Childhood Strabismus in Adults

ABSTRACT

Purpose: To evaluate the factors affecting improvement of stereopsis following successful surgical correction of childhood strabismus in adults.

Methods: In a prospective study, consecutive patients with childhood-onset, comitant, horizontal, constant strabismus; stereoacuity of more than 480 seconds of arc in TNO stereo test (absent stereopsis in TNO); and who had successful postoperative alignment (within 10 prism diopters [PD] of orthotropia) were enrolled. Postoperative stereopsis testing was performed using the TNO stereo test at 3 months after surgery.

Results: A total of 34 patients (20 exotropes and 14 esotropes) were included. The mean age at the time of surgery was 26.08?±?10.53 years (range, 14–53 years). Stereopsis was improved in 8 of 34 patients (23.5%). Postoperative alignment had influence on improvement of stereopsis; 38.1% of patients who had orthotropia gained stereopsis, whereas none of patients who had horizontal heterotropia (esotropia or exotropia) of 10 PD or less gained stereopsis (p?=?0.01). Misalignment of 10 years’ duration or longer did not preclude the development of postoperative stereoacuity (p?=?0.31). There was a statistically insignificant increase in improvement of stereopsis in nonamblyopic group (30.4%) compared with amblyopic group (9.1%) (p?=?0.22). Also, there was a statistically insignificant increase in improvement of stereopsis in exotropes (35%) compared with esotropes (7.1%) (p?=?0.1). The angle of preoperative deviation had no influence on improvement of stereopsis (p?=?0.44).

Conclusion: A postoperative correction of orthotropia was the only predictive factor for improvement of stereopsis in adults with childhood strabismus.     

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.     

Postoperative stereoacuity following realignment for chronic acquired strabismus in adults.

BACKGROUND: There is controversy regarding whether or not visually mature individuals can permanently lose stereoacuity and under what conditions stereoacuity can be regained. Some have proposed a critical duration of misalignment in adults beyond which recovery of fine stereoacuity is not possible, despite successful surgical alignment. METHODS: Twenty-one adult patients (median age 59 years) with large-angle acquired strabismus and who were successfully surgically aligned after 7 to 501 months of misalignment were studied. Subjects had no evidence of motor or sensory fusion since the onset of strabismus, on preoperative exam, or by history. Stereoacuity was measured using 1 or more of the Frisby, Preschool Randot and Titmus tests, at 8 weeks and at 12 months. Data from tests with monocular clues were not used. RESULTS: At total of 67% of patients with chronic acquired strabismus and no preoperative fusion regained measurable stereoacuity and 44% regained fine stereoacuity of at least 60 seconds of arc. Of 10 patients with no or subnormal stereoacuity 8 weeks postoperatively, 6 (60%) showed improvement at the 12-month visit. Misalignment for up to 4 years did not preclude the development of postoperative stereoacuity. CONCLUSIONS: Although a minority of adult strabismus patients may permanently lose stereoacuity despite successful alignment for acquired strabismus, the majority do show recovery. Such recovery of stereoacuity may take several months to occur. In our adult series, duration of misalignment did not predict failure to recover stereoacuity.     

Disruption and reacquisition of binocular vision in childhood and in adulthood

PURPOSE OF REVIEW: This article reviews the most recent studies that address the loss of and restoration of binocular vision in childhood and adulthood and summarizes recent changes in treatment approaches. RECENT FINDINGS: Studies during the last two years support the idea of continued plasticity of the binocular visual system throughout life. Children and adults with strabismus onset following binocular vision maturation are susceptibility to a permanent disruption of stereopsis and sensory fusion. Plasticity of the binocular visual system, however, also means continued restorability of function. Despite a rather short critical time interval for restoration of normal function (three months in children and 12 months in adults), peripheral or extramacular binocular visual function can be restored in most patients whose onset of disruption follows binocular maturation. SUMMARY: Stereoacuity loss can occur in the visually mature patient who develops strabismus later in life and delay of treatment can be deleterious to the restoration of normal macular binocular vision. However, despite any delay of treatment, most patients with strabismus acquired following binocular vision maturation will manifest some stereoacuity or sensory fusion following eye realignment. These findings suggest all patients with strabismus need to have their eyes aligned, either surgically or optically, to maximize their binocular vision outcome.     

Distance stereoacuity norms for the mentor B-VAT II-SG video acuity tester in young children and young adults.

PURPOSE: The purpose of this study was to provide normative distance stereoacuity data for the Mentor B-VAT II-SG video acuity tester (Mentor O & O, Norwell, Mass.). METHODS: Near and distance stereoacuity for 45 normal young children (5 to 6 years old, child group) and 67 normal young adults (16 to 20 years old, adult group) were evaluated. Distance stereoacuity was measured with the Random Dot and the Circles tests on the B-VAT unit. Near stereopsis was assessed by Titmus, Randot, and TNO tests. Additionally, a random subset of the subjects was retested 1 month later with the B-VAT unit. RESULTS: The mean and SD values of stereoacuity measured on the Circles and Random Dot tests were 49 +/- 33 and 98 +/- 49 seconds of arc in children (p < 0.0001) and 50 +/- 32 and 83 +/- 51 seconds of arc in adults (p < 0.0001), respectively. No significant differences were found between the same tests with respect to age. Of 112 subjects in both groups, 110 (98%) achieved 120 seconds of arc or finer stereoacuity threshold levels on the Circles test and 108 (96%) demonstrated 180 seconds of arc or finer scores on the Random Dot test. Although all but two of the subjects exhibited stereopsis both at near and at distance, there were low correlations among the different near and distance stereotests. Test and retest distance stereoacuity scores agreed closely. CONCLUSIONS: The B-VAT II-SG system produces reliable distance stereoacuity data. The norms we obtained may aid the clinician to detect binocular visual disturbances or may provide a basis for using distance stereoacuity as a screening method.     

Intraexaminer repeatability and agreement in stereoacuity measurements made in young adults

AIM: To determine the repeatability and agreement of stereoacuity measurements made using some of the most widely used clinical tests: Frisby, TNO, Randot and Titmus. METHODS: Stereoacuity was measured in two different sessions separated by a time interval of at least 24h but no longer than 1wk in 74 subjects of mean age 20.6y using the four methods. The study participants were divided into two groups: subjects with normal binocular vision and subjects with abnormal binocular vision. RESULTS: Best repeatability was shown by the Frisby and Titmus [coefficient of repeatability (COR): ±13 and ±12s arc respectively] in the subjects with normal binocular vision though a clear ceiling effect was noted. In the subjects with abnormal binocular vision, best repeatability was shown by the Frisby (COR: ±69s arc) and Randot (COR: ±72s arc). In both groups, the TNO test showed poorest agreement with the other tests. CONCLUSION: The repeatability of stereoacuity measures was low in subjects with poor binocular vision yet fairly good in subjects with normal binocular vision with the exception of the TNO test. The reduced agreement detected between the tests indicates they cannot be used interchangeably.     

斜视对双眼视觉功能的影响及术后康复

人类立体视功能的产生有诸多必要条件,双眼平行的视觉方向是其中之一。斜视后双眼的视觉方向不再平行,从而导致双眼视觉功能破坏;同时双眼视觉功能的丧失也意味着中枢对眼位的控制能力变差,进而促进斜视的发展。斜视的主要治疗方法是手术,术后患者可以达到双眼正位,但很多患者的双眼视觉功能并未恢复,一些患者还会由于双眼视觉功能的异常导致短期内斜视复发。因此,斜视的治疗不仅是手术达到双眼正位,术后双眼视觉的康复也同样重要。术后康复训练方法主要包括同视机双眼视觉康复训练、融合能力训练、电脑软件训练、视感知觉训练法等。人类大脑终身具有可塑性,如在术后双眼正位的情况下及时加以适当训练,帮助患者更好地恢复双眼视觉功能,加强大脑对双眼眼位的控制力,更好地保持术后双眼正位。（国际眼科纵览, 2018,  42:   179-183）     

共同性斜视立体视觉的临床检测与分析

目的:研究不同检查方法检测斜视患者立体视锐度的一致性,以及不同类犁斜视立体视损害的差异.方法:对4-25岁双眼视正常组76例及共同性斜视组89例(间歇性外斜39例,恒定性外斜22例,非调节性内斜28例),采用TNO及Randot立体图于40 cm处检查近距离立体视,采用Optec3500视觉检查仪检查远距离立体视,比较3种方法测定的立体视锐度的一致性及不同类型斜视的立体视差异.结果:随机点立体图(TNO)的立体视锐度高于非随机点立体图(Randot与Optec3500)的立体视锐度(P＜0.01);恒定性外斜及内斜TNO近立体视丧失达90%以上,3种方法检查的立体视分布无显著性差异;间歇性外斜的远、近立体视均存在,但其分布有显著性差异(P＜0.05),远立体视的中心凹立体视比例明显降低.结论:立体视损害与斜视偏斜性质无关;随机点及图形立体图对斜视者的检查结果在中心凹立体视一致性好,在黄斑及周边立体视差异较大,故不能仅凭一种检查方法来判断斜视者是否存在立体视.     

成人共同性斜视术后双眼视觉功能重建的临床研究

目的:探讨成人共同性斜视术后双眼视觉功能的重建。方法:观察21例成人共同性斜视患者,用同视机测定三级视功能,用《颜少明立体视检查图》检查近立体视锐度、交叉视锐度及非交叉视锐度,分析比较患者术前,术后3d;6wk;6mo双眼视觉功能的变化。结果:术前16例患者存在单眼抑制,术后6wk有6例患者消除单眼抑制,双眼视觉功能得到重建,差别具有统计学意义(P<0.05);术前具有同视机双眼视觉功能者5例,术后6wk增加至11例,其中7例得到改善,改善率36.8%,差别具有统计学意义(P<0.05);术前存在近立体视者3例,术后6wk增加至7例,其中4例得到改善,改善率22.2%,差别具有显著统计学意义(P<0.01);术前存在正常交叉视锐度者3例,术后6wk增加至7例,其中4例得到改善,改善率22.2%,差别具有显著统计学意义(P<0.01);术前存在正常非交叉视锐度者4例,术后6wk增加至7例,其中3例得到改善,改善率17.6%,差别具有显著统计学意义(P<0.01)。结论:成人共同性斜视术后双眼视觉功能得到不同程度的改善,主要体现在同时视和融合功能,但立体视难以重建,尤其是远立体视;对错过双眼视觉发育敏感期的成人共同性斜视手术,也不应忽视重建患者的双眼视觉功能。     

斜视矫正术对共同性斜视患者双眼视觉功能的影响

目的 探讨共同性斜视患者接受斜视矫正手术前后双眼视觉功能的改变及其影响因素。设计 回顾性病例系列。研究对象 北京同仁医院2013年12月至2014年8月进行斜视矫正术的共同性斜视患者191例。方法 将患者按斜视类型分为共同性内斜视组、恒定性外斜视组和间歇性外斜视组;按手术时年龄分为≤9岁组和＞9岁组。观察术前、术后1、3个月双眼视觉功能。主要指标 同视机双眼视觉三级功能及近立体视功能。结果 191例患者中,术前分别有26.7%、19.4%、11.0%及41.9%的患者具备同视机Ⅰ、Ⅱ、Ⅲ级及近立体视功能,术后1个月分别提高至90.1%、64.4%、33.0%及57.1%,术后3个月分别提高至94.8%、79.1%、37.7%及63.9%,与术前相比均有统计学差异（P均＜0.001）。术前,间歇性外斜视组38.1%、29.5%及72.4%的患者具备同视机Ⅰ、Ⅱ级及近立体视功能,高于另两组（P＜0.01）。术后3个月,间歇性外斜视组93.3%、48.6%及87.6%的患者具备同视机Ⅱ、Ⅲ级及近立体视功能,高于另两组（P均＜0.05）;恒定性外斜视组55.8%的患者具备近立体视功能,共同性内斜视组为14.0%（P＜0.001）。＞9岁组,术前28.1%、21.9%、14.6%及31.3%的患者具备同视机Ⅰ、Ⅱ、Ⅲ级及近立体视功能,术后3个月分别提高至93.8%、75.0%、37.5%及58.3%,与术前相比均有统计学差异（P＜0.01）。结论 斜视矫正术有助于共同性斜视患者双眼视觉功能的改善;间歇性外斜视患者术前术后双眼视觉功能优于其他类型斜视;大龄斜视患者术后也可能获得双眼视觉功能的改善。     

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.     

Stereoacuity development in children with normal binocular single vision.

We made 344 stereoacuity determinations (Titmus Stereotest) on 321 children, ages 1 1/2 to 13 years, who had normal binocular single vision tested by other factors. The data showed a gradual improvement in stereoacuity scores with increasing age--up to age 9--when a normal stereoacuity of 40 seconds of arc was consistently found. The lower limits of stereoacuity compatible with normal binocular single vision were 3 1/2 years, 3,000 seconds; 5 years, 140 seconds: 5 1/2 years, 100 seconds; 6 years, 80 seconds; 7 years, 60 seconds; and 9 years, 40 seconds.