Lang Stereotest Research Articles

Binocular Visual Function Changes After Corneal Collagen Cross-linking in Patients With Keratoconus.

High-order aberrations (HOAs) have been demonstrated to profoundly affect both visual acuity and stereoacuity in patients with keratoconus. Corneal collagen cross-linking (CXL) has been proven to significantly lower HOAs in keratoconus. Yet, to the present date, no evaluation of the effect of the procedure on stereopsis has been performed. The purpose of the study was to assess differences in binocular visual performance in patients with keratoconus before and after CXL. Patients with keratoconus undergoing standard Dresden protocol epi-off CXL in the ophthalmology department of Policlinico Universitario Agostino Gemelli Hospital received slitlamp examination, uncorrected distance visual acuity and corrected distance visual acuity assessment, corneal tomography, Lang stereotest, TNO stereoacuity assessment, distance and near cover test, and Irvine test before surgery and 6 months after CXL. Stereopsis tests were performed with spectacle correction. The analysis included 30 patients (mean age 24.63 ± 3.49 years). The Lang test improved after treatment ( P 0.027), with 6 of 30 patients (20%) showing a positive Lang test before CXL compared with 16 of 30 patients (53.3%) after treatment. Moreover, TNO stereoacuity increased after treatment ( P 0.043), and 14 of 30 patients (46.7%) manifested an improvement of at least 250″ at the TNO test after CXL. In this subgroup of patients, total root mean square values decreased after treatment ( P < 0.001), whereas patients who did not manifest a clinically significant improvement in stereoacuity did not show a reduction in total root mean square values after CXL ( P = 0.11). The results of cover test and Irvine test did not vary after CXL. Patients with keratoconus showing a reduction of HOAs after CXL also manifest a significant improvement in stereoacuity after the treatment.

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.

Global motion perception is associated with motor function in 2-year-old children

The dorsal visual processing stream that includes V1, motion sensitive area V5 and the posterior parietal lobe, supports visually guided motor function. Two recent studies have reported associations between global motion perception, a behavioural measure of processing in V5, and motor function in pre-school and school aged children. This indicates a relationship between visual and motor development and also supports the use of global motion perception to assess overall dorsal stream function in studies of human neurodevelopment. We investigated whether associations between vision and motor function were present at 2 years of age, a substantially earlier stage of development. The Bayley III test of Infant and Toddler Development and measures of vision including visual acuity (Cardiff Acuity Cards), stereopsis (Lang stereotest) and global motion perception were attempted in 404 2-year-old children (±4 weeks). Global motion perception (quantified as a motion coherence threshold) was assessed by observing optokinetic nystagmus in response to random dot kinematograms of varying coherence. Linear regression revealed that global motion perception was modestly, but statistically significantly associated with Bayley III composite motor (r2=0.06, P<0.001, n=375) and gross motor scores (r2=0.06, p<0.001, n=375). The associations remained significant when language score was included in the regression model. In addition, when language score was included in the model, stereopsis was significantly associated with composite motor and fine motor scores, but unaided visual acuity was not statistically significantly associated with any of the motor scores. These results demonstrate that global motion perception and binocular vision are associated with motor function at an early stage of development. Global motion perception can be used as a partial measure of dorsal stream function from early childhood.

Neurological and neuropsychological characteristics of occipital, occipito-temporal and occipito-parietal infarction

Neuropsychological deficits after occipital infarction are most often described in case studies and only a small sample of studies has attempted to exactly correlate the anatomical localization of lesions with associated neuropsychological symptoms. The present study investigated a large number of patients (N = 128) in order to provide an overview of neurological and neuropsychological deficits after occipital, occipito-temporal and occipito-parietal infarction. A particular approach of the study was to define exact anatomical correlates of neuropsychological dysfunction by using voxel-based lesion-symptom mapping (VLSM) in 61 patients. In addition to a visual field defect and phosphenes, patients often reported anomia, difficulties in reading and memory deficits. Visual disorders, such as achromatopsia, akinetopsia or prosopagnosia, were rarely reported by the patients. Memory and visual disorders were diagnosed efficiently using simple clinical screening tests, such as the Rey–Osterrieth Complex Figure Test for immediate recall, the Demtect and the Lang Stereo Test. Visual field defects, reading disorders and the perception of phosphenes were associated primarily with lesions of the calcarine sulcus. Anomia and memory deficits were related to lesions of the occipital inferior gyrus, the lingual gyrus and hippocampus, as well as to lesions of principal white matter tracts.

Changes of saccadic eye movements in thyroid-associated ophthalmopathy

To establish whether or not the dynamics of saccadic eye movements are significantly changed in patients with different stages of thyroid-associated ophthalmopathy (TAO) and, subsequently, if analysis of saccades could serve as an additional diagnostic tool for early detection of inflammatory activity in TAO. Thirty-seven patients with TAO and 10 age- and gender-matched control subjects were investigated. The patients were divided into four groups according to the stage of the disease: (i) early mild disease (n = 10), (ii) early severe disease (n = 11), (iii) long-standing restrictive disease (n = 10) and (iv) proven auto-immune hyperthyroidism without any signs of TAO (n = 6). Horizontal and vertical saccades with amplitudes of 10°, 20°, 30° and 40° were recorded binocularly using the induction scleral search coil technique. The two main sequence constants V(max) and C were calculated for each eye. Repeated measurement analysis of variance was carried out to test for differences between different gaze directions, eyes and groups. In horizontal saccades, significant differences were found between groups but not between abduction and adduction. In vertical saccades, differences between groups and the interaction between groups and up- and down-gaze saccades were significant. Compared with the control group, analysis of the main sequence curves revealed larger differences in patients of group 3 and 4 than in those of group 1 and 2. Whereas in the control group down-gaze saccades were faster than up-gaze saccades, the opposite behaviour was found in all patient groups. The largest differences were detected among those patients who had no signs of TAO (group 4). In this study, significant saccade differences were detected in all patients with TAO. In contrast to our earlier studies where evaluation of multiple individual saccade parameters did not reveal significant differences, analysis of the main sequence constants and mathematical reconstruction of the main sequence curves turned out to be a sensitive technique for reliable detection of subtle ocular motility changes. Significant differences were detected even in patients with auto-immune thyroiditis where no clinical signs of TAO were apparent.

Vision screening in children by Plusoptix Vision Screener compared with gold-standard orthoptic assessment

Background/aims:To evaluate a new autorefractor, the Plusoptix Vision Screener (PVS), as a screening tool to detect risk factors for amblyopia by comparing it with gold-standard orthoptic vision screening in children.Methods:Community-based...

Vision screening in children with developmental delay can be improved: analysis of a screening programme outside the ophthalmic clinic

The purpose of the present study was to evaluate the effectiveness of a new vision-screening programme in detecting ophthalmic disorders in children with developmental delay (DD; IQ< or =80) and in children with normal IQ. A group of 467 children with an IQ< or =80 (272 males, 195 females; age range 4-15y; mean age 10y 4mo [SD 2y 10mo]) and 123 children with an IQ>80 (85 males, 38 females; age range 3-16y; mean age 10y 5mo [SD 3y 2mo]) had an examination that included new vision-screening items: distance and near visual acuity and stereopsis for near objects (Lang stereo test II). A full ophthalmological examination was also conducted to determine the effectiveness of the new screening items. The previous screening programme consisted of only monocular visual acuity at distance. Sensitivity, specificity, the positive predictive value (PPV), and negative predictive value (NPV) of the tests were calculated with regard to the following ophthalmic disorders: hyperopia, myopia, astigmatism, anistometropia, amblyopia, low vision, and strabismus. Overall, the prevalence of ophthalmic disorders was 33.4% in children with DD and 11.4% in typically developing children. With the use of the new programme, the effectiveness of vision screening in both groups of children was improved. In children with DD, sensitivity increased from 49.4 to 80.1%, specificity decreased from 98.1 to 83.3%, PPV decreased from 92.8 to 70.6%, and NPV increased from 79.4 to 89.3%. In typically developing children, sensitivity improved from 50.0 to 85.7%, specificity declined from 98.2 to 87.2%, PPV decreased from 77.8 to 46.2%, and NPV increased from 93.9 to 97.9%. We conclude that the currently used vision-screening programme can be significantly improved. The speed and simplicity of the proposed screening programme makes it suitable for use by school nurses. The improvements were most prominent in children with DD.

Esotropie précoce: résultats à long terme d’une série de 82 cas opérés par myopexie rétro-équatoriale et recul simultané des deux muscles droits médiaux avant l’âge de 24 mois

When and how to operate an early-onset esotropia (onset before 6 months of age) is still controversial. We conducted a retrospective study of such patients operated before the age of 24 months. 82 patients were operated by one surgeon (GK) and followed by the same team. At 5 years post-operation, evaluation criteria included the residual angle of deviation, visual acuity (Birkhäuser Nr 505, 5 m) and binocularity (Lang stereotest I, Bagolini glasses). At 5 years, the residual angle was excellent (0 degrees to + 5 degrees ) in 67 % good, (>+5 degrees to +10 degrees or 0 to -5 degrees ) in 23 %, and poor (>+10 degrees or <-5 degrees ) in 10 %. During the 5 years of follow-up the rate of reoperation was 9.7 %. Isoacuity was obtained in 62 %, slight amblyopia (2 lines of interocular difference) was present in 32 %, and average amblyopia (> 3 lines of interocular difference) was noted in 6 %. Simultaneous perception was present in 53 %, whereas one eye was suppressed or results were undetermined in 47 %. No patient demonstrated stereoscopy using the Lang's stereotest I. The results from our study demonstrate that early surgery of early-onset esotropia has a favourable outcome on both visual acuity and the residual angle of strabismus. Simultaneous perception was achieved in 53 %. These figures are comparable to the results of the ELISSS multicentric study.

Strabismus and binocular function in children with Down syndrome. A population-based, longitudinal study.

We have performed a population-based, longitudinal study on strabismus in children with Down syndrome. The aims of the study were to examine the frequency and type of strabismus, the age at onset, and the binocular potential. An unselected population of 60 children with Down syndrome born 1988-1999 was followed with repeated examinations. Mean follow-up time was 55+/-23 months (range 24--115). The alignment of the eyes was examined using Hirschberg corneal reflex test and cover test for near fixation. To evaluate binocular function, Titmus House Fly Test and Lang's stereo test were used. Twenty-five patients (42%) had strabismus (21 esotropias, two exodeviations and two vertical deviations). Only one case of infantile esotropia was found, the other esotropias were acquired forms. The mean age at "onset" (e.g. when strabismus was first noticed) was 54+/-35 months. In the acquired esotropia group (n=20), 15 (75%) were associated with hypermetropia (mean spherical equivalent +4.3+/-1.7 D). Seventeen of the strabismic patients had an accommodation weakness. Eleven of the strabismus patients gave a clearly positive response to one or both stereotests. The majority of the Down syndrome children with strabismus have an acquired esotropia and hence a potential for binocularity. Hypermetropia and accommodation weakness are probably important factors in esotropia in Down syndrome patients.

Preliminary report: Examination of young children with Lea symbols

Lea symbols are highly sensitive for detection of amblyopia in cooperative patients. They are favorable for visual acuity assessment in childhood. Therefore, we assessed age-related normal values and interocular differences of Lea symbol visual acuity. We reexamined 50 out of 193 children aged 21 months to 7 years who came for a routine pediatric examination between January and November 1999. Lea symbol acuity (Lea Symbols Single Symbol Book (LS) and Lea 15-Line Folding Distance Chart (CLS)) and Landolt-C acuity (single (LC) and crowded with 2.6' inter-optotype distance (LC(2.6))) were measured. A three out of four criterion was used. Strabismus and any organic eye disease were excluded by orthoptic and ophthalmologic examination, consisting of biomicroscopy, ophthalmoscopy, retinoscopy or refractometry, cover test or Hirschberg test and Lang Stereotest. Only 26% of the parents (50 out of 193) accepted an examination in our hospital. In 35 (32) of the 50 children, visual acuity could be measured in both eyes separately with single (crowded) Lea symbols, while 26 (25) children could be examined in both eyes monocularly with the Landolt-C with single (crowded) optotypes. Except for one 3-year-old boy, all of the children older than 30 months could be tested with single Lea symbols. Lea acuity surpassed Landolt acuity. The difference was about 1.5 lines (1.5 dB) for both the single and the crowded optotypes. In 63% (69%) of the children who could be tested monocularly, LS acuity (CLS acuity) was higher than 0.8 (0.63). 89% (83%) of the children had an interocular difference of maximum 1 line for single (crowded) Lea symbols. The youngest child whose visual acuity could be assessed with Lea symbols was 23 months old. Almost every child older than 30 months could be tested with Lea symbols. Lea acuity higher than 1 and an interocular difference less than 2 lines is not suspect for amblyopia. Children with a difference of more than one line should be reexamined.

Suitability of the Lang II Random Dot Stereotest for detecting manifest strabismus in 3‐year‐old children at child health centres in Sweden

The aim of the study is to examine the suitability of the Lang II Random Dot Stereotest for use by district nurses in primary healthcare centres. The Lang Stereotest is an inexpensive method. It is easy to apply, but the child's co-operation is required. Approximately 100 district nurses were given detailed information and instruction by an orthoptist prior to a randomized population-based community trial initiated in 1993. In the county of Uppsala in Sweden, all 4293 children born in 1990 were randomized to one of the following four study groups: intervention, control, reliability or validity. All children were followed from birth to 6.5 y of age with respect to the occurrence of strabismus. The kappa statistic for test-retest reliability among district nurses was 0.65 (95% CI, 0.51-0.80). A validation of the outcomes of district nurses' against orthoptists' examinations using the Lang Stereotest showed a sensitivity of 0.33 (95% CI, 0.09-0.65) and a specificity of 0.85 (0.80-0.89). Of 113 cases of strabismus, 53% were detected within the first 3 y of life. Examination of 1132 3-y-old children using the Lang Stereotest enabled the district nurses to detect 11 new cases of strabismus. Only one of these cases was referred to an orthoptist as a direct consequence of the screening. The Lang Stereotest showed low reliability and low validity in this community trial. It is concluded that the Lang II Random Dot Stereotest is not suitable for the screening of manifest strabismus in unselected populations of 3-y-old children in Sweden, where a large proportion of cases of strabismus is detected during the first 3 y of life.

Preliminary report: Examination of young children with Lea symbols

BACKGROUND. Lea symbols are highly sensitive for detection of amblyopia in cooperative patients. They are favorable for visual acuity assessment in childhood. Therefore, we assessed age-related normal values and interocular differences of Lea symbol visual acuity. METHODS/PATIENTS. We reexamined 50 out of 193 children aged 21 months to 7 years who came for a routine pediatric examination between January and November 1999. Lea symbol acuity (Lea Symbols Single Symbol Book (LS) and Lea 15-Line Folding Distance Chart (CLS)) and Landolt-C acuity (single (LC) and crowded with 2.6' inter-optotype distance (LC 2.6 )) were measured. A three out of four criterion was used. Strabismus and any organic eye disease were excluded by orthoptic and ophthalmologic examination, consisting of biomicroscopy, ophthalmoscopy, retinoscopy or refractometry, cover test or Hirschberg test and Lang Stereotest. RESULTS. Only 26% of the parents (50 out of 193) accepted an examination in our hospital. In 35 (32) of the 50 children, visual acuity could be measured in both eyes seperately with single (crowded) Lea symbols, while 26 (25) children could be examined in both eyes monocularly with the Landolt-C with single (crowded) optotypes. Except for one 3-year-old boy, all of the children older than 30 months could be tested with single Lea symbols. Lea acuity surpassed Landolt acuity. The difference was about 1.5 lines (1.5 dB) for both the single and the crowded optotypes. In 63% (69%) of the children who could be tested monocularly, LS acuity (CLS acuity) was higher than 0.8 (0.63). 89% (83%) of the children had an interocular difference of maximum 1 line for single (crowded) Lea symbols. CONCLUSIONS. The youngest child whose visual acuity could be assessed with Lea symbols was 23 months old. Almost every child older than 30 months could be tested with Lea symbols. Lea acuity higher than 1 and an interocular difference less than 2 lines is not suspect for amblyopia. Children with a difference of more than one line should be reexamined.

Motion Perception Tested With Reversing Grating in Duane’s Syndrome

Many papers have reported that motion perception asymmetry (MPA) is replaced by motion perception symmetry (MPS) by the 4th to 5th month after birth, when stereopsis starts to occur in normal infants. Duane’s syndrome is a congenital motor abnormality, it does, however, reportedly show good stereopsis. We confirmed the stereopsis in Duane’s syndrome and checked the motion perception (MP) by using the Reversing Grating Test to investigate if the congenital motor abnormality affects the MP in patients whose binocular sensory system is well developed. Thirty-eight Duane’s syndrome patients aged 3 to 45 years were included in the present study. They were divided into 24 cases of Duane I, 9 cases of Duane II, 5 cases of Duane III. The Titmus Stereo Tests, Lang Stereotest, and TV-Random Dot Stereo Test were used to examine the stereopsis. Thirty-four patients had good stereopsis, and 4 had poor stereopsis. None of them showed MPA in any spatial frequencies (1/4, 1/2, 1 cycles/degree) examined. The Reversing Grating Test is useful for examining MPA in strabismus patients with eye movement limitations.

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Testing Stereopsis in the Preschool Child: Is It Clinically Useful?

The evaluation of stereoacuity should provide an unambiguous assessment of binocular function in infants and young children. Unfortunately, clinical measures of stereopsis in these young patients often result in stereotheresholds poorer than the criteria suggested to differentiate normal from anomalous binocular vision. Thus, two experiments were conducted to determine whether the large stereothresholds frequently demonstrated on tests designed for young children are diagnostic of normal binocular function in preschool children. The first experiment investigated the salience of the monocular cues in the Lang and Frisby stereotests in normal preschool children (2 to 5 years old). None of the children who passed either the Frisby or the Lang stereotest under binocular conditions were able to pass either test monocularly, even after passing the test binocularly. In the second experiment, preschool children with abnormal binocular vision were tested with the Lang and Frisby stereotests to determine if large disparities (730 to 800 seconds of arc [arcsec]) could be passed without normal binocular vision. None of the children with strabismus passed either stereotest. However, two children with anisometropia passed the Frisby test and one of these children also passed the Lang test. These results suggest that in the absence of other clinical findings to the contrary, the demonstration of gross stereopsis with either the Frisby (730 arcsec) or Lang (733 or 800 arcsec) test in the preschool child implies normal binocular function. Thus, clinical tests of stereopsis for infants and preschool children, like those used routinely for adults, can provide evidence of binocular function without approaching stereothreshold.

An evaluation of techniques for measuring stereopsis in infants and young children

Demonstrating stereopsis is valuable in vision screening of infants and toddlers, since its presence rules out the possibility of profound visual deficits. We assessed the performance of 55 infants and young children on three clinically available tests, the Lang, the Frisby and the TNO. The results were compared with those found using a computerized dynamic random dot stereogram. Most of the children tested were under 3 years of age and 10 were aged under 1 year. The Lang test was passed by 74%, including 50% of those under 1 year. The Frisby test was passed by 65%, but by only 20% of infants under 1 year. Forty-nine per cent passed the TNO test; none were under 1 year. The computerized stereogram was passed by 42.5% of those tested, including 100% of those over 3 years old. Both this test and the TNO presented difficulty in testing infants between 8 months and 2 years because of the increased likelihood that these children would reject the red/green glasses. We recommend that the most appropriate stereotest is largely based on whether the child will tolerate red/green glasses. We would use the dynamic random dot test for infants under 8 months of age, the Lang or Frisby stereotest for infants from 8 months to 30 months, and the TNO or dynamic random dot stereogram after this age.

An evaluation of techniques for measuring stereopsis in infants and young children

Demonstrating stereopsis is valuable in vision screening of infants and toddlers, since its presence rules out the possibility of profound visual deficits. We assessed the performance of 55 infants and young children on three clinically available tests, the Lang, the Frisby and the TNO. The results were compared with those found using a computerized dynamic random dot stereogram. Most of the children tested were under 3 years of age and 10 were aged under 1 year. The Lang test was passed by 74%, including 50% of those under 1 year. The Frisby test was passed by 65%, but by only 20% of infants under 1 year. Forty-nine per cent passed the TNO test; none were under 1 year. The computerized stereogram was passed by 42.5% of those tested, including 100% of those over 3 years old. Both this test and the TNO presented difficulty in testing infants between 8 months and 2 years because of the increased likelihood that these children would reject the red/green glasses. We recommend that the most appropriate stereotest is largely based on whether the child will tolerate red/green glasses. We would use the dynamic random dot test for infants under 8 months of age, the Lang or Frisby stereotest for infants from 8 months to 30 months, and the TNO or dynamic random dot stereogram after this age.

Seven years of clinical experience with the Lang Stereotest in young children

Seven years of clinical experience with the Lang Stereotest in young children

Eye Screening with the Lang Stereotest

The Lang Stereotest is based on a random-dot pattern and cylinder gratings. Cylinder gratings provide a haploscopic testing device which does not require glasses. The youngest child to pass the tes...

Visual acuity and stereopsis between the ages of 5 and 10 years. A cross-sectional study.

The development of visual acuity and stereopsis was studied in 321 boys and 340 girls aged between 5 and 10 years. Visual acuity was assessed by the E test and a modified version of the STYCAR test, stereo acuity by the Lang-Stereo test [17]. Both vision tests showed an increase in the median visual acuity between the ages of 5 and 10 years. The E test indicated an increase from 1.2 between 5 and 6 years to 1.5-1.7 between 7 and 10 years. The values obtained with the STYCAR test were 0.6-1.3 higher, depending on the test rating used. Visual acuity norms between 5 and 10 years are presented as empirical centile curves. No significant differences were observed in visual acuity between the left and right eyes, nor between the sexes. The right eye was found to be the leading eye in 54.8% of the boys and 54.5% of the girls (P less than 0.001). The Lang-Stereo test was passed by 87.9%-94.3% of all children, and there were no significant differences with respect to age and sex. Children who failed the test had a significantly lower visual acuity than those who passed it. In the former group a significant interocular difference in visual acuity was present (P less than 0.01).