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

Quantifying Suppression in Anisometropic Amblyopia With VTS4 (Vision Therapy System 4)

Purpose

Visual acuity (VA) of the amblyopic eye is usually considered for monitoring improvement with therapy. However, participation of the amblyopic eye under binocular viewing conditions is also important. This study investigated the use of a clinically available tool VTS4 (Vision Therapy System 4) to quantify the participation or suppression of the amblyopic eye under binocular viewing conditions.

Methods

A cross-sectional study on patients with anisometropic amblyopia was undertaken. Monocular VA was thresholded. Stereo acuity was measured with Randot stereo test. Simultaneous macular perception (SMP) targets in VTS4 were dichoptically presented. SMP target size was reduced till the amblyopic eye's target disappeared (suppression scotoma size). An average of three measurements was taken for the suppression scotoma size.

Results

Twenty-eight patients participated (aged 6 to 21 years). The mean interocular VA difference was 0.50 ± 0.27 logMAR. The mean scotoma size was 8.2° ± 5.4°. Mean stereo acuity was 2.06 ± 0.34 log arc seconds from 21 patients on whom stereopsis could be measured. Suppression scotoma size showed a significant (P < 0.001) positive correlation with both interocular VA difference (r = 0.59) and stereoacuity (r = 0.72).

Conclusions

Participation of the amblyopic eye under binocular viewing condition can be assessed by measuring the suppression scotoma size in VTS4, even when stereoacuity is poor or not measurable. Smaller the suppression scotoma, better is the amblyopic eye's participation.

Translational Relevance

VTS4 can be used in monitoring amblyopia therapy by quantifying suppression of the amblyopic eye.

Characterizing the Randot Preschool stereotest: Testability, norms, reliability, specificity and sensitivity in children aged 2-11 years

PURPOSE

To comprehensively assess the Randot Preschool stereo test in young children, including testability, normative values, test/retest reliability and sensitivity and specificity for detecting binocular vision disorders.

METHODS

We tested 1005 children aged 2-11 years with the Randot Preschool stereo test, plus a cover/uncover test to detect heterotropia. Monocular visual acuity was assessed in both eyes using Keeler Crowded LogMAR visual acuity test for children aged 4 and over.

RESULTS

Testability was very high: 65% in two-year-olds, 92% in three-year-olds and ~100% in older children. Normative values: In 389 children aged 2-5 with apparently normal vision, 6% of children scored nil (stereoblind). In those who obtained a threshold, the mean log threshold was 2.06 log10 arcsec, corresponding to 114 arcsec, and the median threshold was 100 arcsec. Most older children score 40 arcsec, the best available score. We found a small sex difference, with girls scoring slightly but significantly better. Test/retest reliability: ~99% for obtaining any score vs nil. Agreement between stereo thresholds is poor in children aged 2-5; 95% limit of agreement = 0.7 log10 arcsec: five-fold change in stereo threshold may occur without any change in vision. In children over 5, the test essentially acts only as a binary classifier since almost all non-stereoblind children score 40 arcsec. Specificity (true negative rate): >95%. Sensitivity (true positive rate): poor, <50%, i.e. around half of children with a demonstrable binocular vision abnormality score well on the Randot Preschool.

CONCLUSIONS

The Randot Preschool is extremely accessible for even very young children, and is very reliable at classifying children into those who have any stereo vision vs those who are stereoblind. However, its ability to quantify stereo vision is limited by poor repeatability in children aged 5 and under, and a very limited range of scores relevant to children aged over 5.

Screening for Stereopsis of Children Using an Autostereoscopic Smartphone

Background

The advantage of using an autostereoscopic smartphone is that it can achieve 3D effects without the need for glasses. The purpose of this study was to evaluate whether this technology could be utilized to detect stereoacuity.

Methods

An autostereoscopic smartphone was used to imitate Lang stereotest I & II, Pass Test 3, Dinosaur Stereoacuity Test, and the Random Dot Stereo Acuity Test to screen the stereopsis of children from 3–6 years old.

Results

No significant difference was found between each pair of groups (autostereoscopic smartphone vs. Lang stereotest I, Lang stereotest II, Pass Test 3, Dinosaur Stereoacuity Test, and Random Dot Stereo Acuity Test, respectively; Wilcoxon signed-rank test, P value all >0.05). All of the weighted kappa were higher than 0.84. Therefore, all of the comparisons between measurements showed a high level of agreement.

Conclusions

The autostereoscopic smartphone is an effective tool when used for the screening of deficiency in stereopsis.

Effect of chromatic contrast on stereoacuity measurement with computer-aided three-dimensional technology

Background

Various measurement tools are utilized to detect the stereopsis threshold in the clinic, but seldom of these involves chromatic information. Incorporating colorful elements into computer-aided, three-dimensional (3D) evaluation systems could help the tests appear more vivid and attractive. The aim of this study was to clarify the effect of different chromatic pair stereo targets on the stereoacuity result.

Methods

A total of 17 subjects with visual acuity in each eye of at least 0 logarithmic minimum angle of resolution (logMAR) and a stereoacuity of at least 32 second of arc (arcsec) were recruited. A 3D laptop with liquid crystal shutter glasses was used for evaluating stereoacuity. Thirteen pages were set including seven maximum color contrast pages and six isoluminant color contrast pages.

Results

In maximum color contrast pair, no significant difference was found among all seven experiments [six test groups and one reference group, one-way analysis of variance (ANOVA) test, F=0.995, P=0.493]. There was also no significant difference among the isoluminant color contrast pairs (six test groups, one-way ANOVA test, F=0.873, P=0.644). Paired t-test was used for comparing the data between the same hue series in the maximum color contrast pair vs. the isoluminant color contrast pair, and significant differences were found in all six pairs (P<0.001).

Conclusions

Adding chromatic factors to the stereo test is practical to evaluate stereopsis.

Statistics of TNO stereotest for the diagnosis of microesotropia in children

PURPOSE

To analyze statistically the real effectiveness of TNO stereotest for the diagnosis of microesotropia in young patients in daily practice.

METHODS

We considered 312 patients whose age ranged from 3 to 18 years (mean age 7.5 years) suspected to be microesotropic. All underwent a full orthoptic and ophthalmologic examination. The TNO stereotest was presented at a distance of 40 cm with the patient wearing red-green glasses. The Paliaga 8-D base-in test was considered the gold standard diagnostic test to detect microesotropia.

RESULTS

The specificity of the TNO stereotest from the collected data was 98%, the sensitivity 94%, the positive predictive value 80%, the negative predictive value 99%, and the likelihood ratio 47.

CONCLUSIONS

It is important to use the TNO stereotest in clinical daily practice to detect microesotropia, but considering some bias: the age of the young patients, the difficulties encountered in understanding some figures, and the presence of a stereoscopic status even in microtropic subjects.

Evaluating stereoacuity with 3D shutter glasses technology

Background

To determine the stereoacuity threshold with a 3D laptop equipped with 3D shutter glasses, and to evaluate the effect of different shape and size of test symbols and different type of disparities to stereoacuity.

Methods

Thirty subjects with a visual acuity in each eye of at least 0 logMAR and a stereoacuity of at least 32 arcsec (as assessed in Fly Stereo Acuity Test) were recruited. Three target symbols—tumbling "E", tumbling "C", and "□"—were displayed, each with six different sizes representing a visual acuity ranging from 0.5 to 0 logMAR when tested at 4.1 m, and with both crossed and uncrossed disparities. Two test systems were designed - fixed distance of 4.1 m and one for variable distance. The former has disparities ranging from 10 to 1000 arcsec. Each subject completed 36 trials to investigate the effect of different symbol sizes and shapes, and disparity types on stereoacuity. In the variable distance system, each subject was tested 12 times for the same purposes, both proximally and distally (the point where the 3D effect just appears and where it just disappears respectively), and the mean value was calculated from the mean proximal and distal distances.

Results

No significant difference was found among the groups in the fixed distance test system (Kruskal-Wallis test; Chi-square = 29.844, P = 0.715). Similarly, no significant difference was found in the variable distance system (Kruskal-Wallis test; proximal: Chi-square = 5.687, P = 0.338; distal: Chi-square = 5.898, P = 0.316; mean: Chi-square = 6.152, P = 0.292).

Conclusions

Evaluating stereoacuity using this measurement system was convenient and effective. Changes in target shape and size and disparity types had no significant effect on stereoacuity. It would be helpful to choose optimal targets according to different purposes using computer-assisted 3D measurements.

Electronic supplementary material

The online version of this article (doi:10.1186/s12886-016-0223-3) contains supplementary material, which is available to authorized users.

Reliability and validity of an automated computerized visual acuity and stereoacuity test in children using an interactive video game

PURPOSE

To evaluate the test-retest reliability and validity of the new automated computerized distance visual acuity and stereoacuity test for children, which uses an interactive video game.

DESIGN

Retrospective, observational case series.

METHODS

A total of 102 children aged between 3 and 7 years underwent the Snellen visual acuity test, the Distance Randot Stereotest, and the new automated computerized distance visual acuity and stereoacuity test. The test-retest reliability and validity of the automated computerized tests were assessed and compared with the Snellen visual acuity test and the Distance Randot Stereotest with frequency distributions of the differences, Bland-Altman plots, and Deming regression.

RESULTS

The automated computerized distance visual acuity test had high test-retest reliability (95% limits of agreement ±0.18 logMAR, 90.0% of the differences within 0.2 logMAR) and acceptable validity as compared with the Snellen visual acuity chart (95% limits of agreement ±0.27 logMAR, 81.3% of the differences within 0.2 logMAR). The automated computerized distance stereoacuity test had high test-retest reliability (95% limits of agreement ±0.29 log arc second, 95.1% of the differences within 0.3 log arc second) and acceptable validity as compared with the Distance Randot Stereotest (95% limits of agreement ±0.35 log arc second, 93.9% of the differences within 0.3 log arc second).

CONCLUSIONS

The new automated computerized distance visual acuity and stereoacuity test, which uses an interactive video game, has good reliability and acceptable validity compared with the Snellen visual acuity chart and the Distance Randot Stereotest.