Degree Of Stereopsis Research Articles

Refractive Profile of Surgical Patients with Intermittent Exotropia: A Large-Sample Cross-Sectional Study in Southern China

Purpose To describe the refractive profile of surgical patients with intermittent exotropia (IXT) residing in southern China. Methods Medical records of patients who received strabismus surgery between June 2014 and August 2020 were retrospectively reviewed. Clinical data, including age, sex, refractive errors, preoperative angle of deviation, types of exotropia, accommodative convergence to accommodation ratio (AC/A ratio) and stereopsis, were investigated. Results A total of 2250 patients were included, and 93.6% of patients were younger than 30 years of age. The mean angle of exodeviation was 37.0 ± 14.7 prism degree (PD) and 37.5 ± 15.8 PD at distance and near, respectively. Mean spherical equivalent refraction (SER) values were -0.7 ± 2.4 D and −0.8 ± 2.5 D in the dominant eye and nondominant eye, respectively. Significant differences in SER were observed between the dominant eye and nondominant eye among children at 6 years old or younger. The percentage of myopia increased from 11.0% in children (≤6 years old) to 77.9% in teenagers (13-18 years of age). Significant positive associations between the magnitude of exodeviation and the magnitude of myopia were observed (p < 0.0001). Patients with convergence insufficiency type IXT (p < 0.0001) or AC/A < 2 (p < 0.05) showed a greater magnitude of myopia. The mild hyperopia group included a larger proportion of subjects showing a certain degree of stereopsis (p < 0.05). Conclusions Myopia was present in more than half of our patients (51.2%), which is much higher than the percentage in the general population of southern China. Patients with convergence insufficiency, an AC/A ratio < 2, or a larger angle of deviation tended to have a greater magnitude of myopia.

Visual Performance and Perceptual–Motor Skills of Late Preterm Children and Healthy Controls Using the TVPS-3rd and VMI-6th Editions

Background: The visual system is key to the learning process, preterm births are commonly followed by visual dysfunctions and other neurological conditions. Objective: to measure, analyze and compare the visual efficacy, visual–perceptual, and visual–motor skills of 20 late preterm children (34–36 weeks) born by caesarean section and appropriate weight for gestational age with 20 healthy controls born at full term by natural birth, age 5 to 12 years, from Querétaro, México. Methods: This was an observational, transverse, and prospective study. Parametric and non-parametric tests were performed using the SPSS 25.0. The visual acuity at distance and near, the phoria state, and the degree of stereopsis were analyzed. The Test of Visual-Perceptual Skills, Third Edition, was used to assess the overall performance, basic, sequencing, and complex processes. Fine motor skills were evaluated using the Visual–Motor Integration Test of Beery, Sixth Edition. Results: Visual acuity at distance and near (p&lt;0.001), stereopsis (p&lt;0.001), and the amount of exophoria at distance (p=0.01) showed statistically significant differences between the groups. The overall performance (p=0.006), basic processes (p=0.001), sequencing processes (p=0.02), and General and Motor VMI (p&lt;0.001 and 0.002, respectively) presented lower values in children born preterm. Conclusion: This research showed that even late preterm children present visual deficiencies and are at risk of delays on perceptual–motor skills. Early evaluation of their visual and motor abilities should be considered in order to help improve their cognitive functioning.

Differences in the Visual Performances of Patients with Strabismus, Amblyopia, and Healthy Controls.

A total of 398 participants were divided in three groups: HCs, PRA, and PS. Variables such as visual acuity, refractive state, degree of stereopsis, phoria state, magnitude, and type of deviation were analyzed using parametric and non-parametric tests. Binocular visual acuity at near is the unique predictor factor for stereopsis in PRA and PS, while age relates to the amount of binocular visual acuity at near, only for PS with stereopsis. Binocular visual acuity at near and phoria states relate to each other in PRA. Binocular visual acuity at near and far in PS is better than PRA, with no differences in the degree of stereopsis. Stereoblind patients were only found among PS (36%). Only (44.9%) of PS had amblyopia. Exophoria predominated among PRA (69.72%) and HCs (78.87%), while exotropia was the predominant deviation in PS (60.54%). Hyperopia was the predominate refractive error among the groups, HCs (74.65%), PRA (79.82%), and PS (59.85%), followed by astigmatism. HCs perform better than PS and PRA. The visual performance of PS with stereopsis and PRA is similar. Binocular visual acuity at near can predict the degree of stereopsis, and stereoblind patients are exclusively related to strabismus.

Simplification of the complex: Successful management of large-angle exodeviation after endoscopic sinus surgery.

To report the clinical characteristics and successful management of large-angle exodeviation due to medial rectus muscle (MR) transection incurred during endoscopic sinus surgery (ESS). The medical records of 5 consecutive inpatients with MR complete transection following ESS resulting in large-angle paralytic exodeviation between November 2014 and June 2021 were reviewed. The type of muscle injury, clinical characteristics, surgical procedure and dosage, and long-term outcomes were evaluated. All 5 patients manifested exodeviations of 72 PD to >133 PD with no adduction capacity (graded -4); all of them had proven orbital trauma and complete MR transection with a ≥20 mm distal (globe attached) stump based on CT scans and/or MRI imaging. They underwent a supra-maximal recession (10-12 mm) of the lateral rectus and resection (10-15 mm) of the medial rectus on the affected eye. At least 1 year (1 to 5 years) following the corrective surgery, the patients still maintained orthophoria or had a small angle of exotropia (≤ 8 PD) in primary gaze with successful fusion, and 3 of them (Case 3, 4, and 5) exhibited a certain degree of stereopsis. In addition, appreciable adduction occurred (graded -1 to -3). A supra-maximal recession/resection shows favorable outcomes in patients with proven complete transection MR with a ≥20 mm distal (globe attached) stump. It can help to achieve good ocular alignment and even yield improvements in adduction over time.

Outcome of surgery for near angle in patient with incomitant distance/near esotropia and without manifest deviation at distance.

To investigate how a subset of patients with partially accommodative esotropia, with a manifest deviation <10 Prism Diopters (PD) at distance and an angle of strabismus at near wider than 10 PD, could respond to a surgical approach based on the misalignment at near. Six patients examined from 2015 to 2019 met criteria for inclusion: partially accommodative esotropia, patients compliant to full correction for at least 6 months, angle of esotropia for near larger at least 10 PD, angle of misalignment obtained with the alternate prism cover test and simultaneous prism cover test at distance <10 PD. All patients underwent bilateral medial recti recession. They were examined at 3 weeks and at 6 months. No significant difference in the angle of esotropia at distance was found at any follow-up (Baseline: 7.17 ± 1.33 PD vs 3 weeks: 7.0 ± 1.01 PD vs 6 months: 7.33 ± 1.03 PD, p = 0.65, and p = 0.36, respectively). No case of consecutive exotropia was described. Considering the angle at near, there was a significant reduction at 3 weeks (Baseline: 41.7 ± 6.83 PD vs 3 weeks: 9.33 ± 1.63 PD, p = 0.027), that remained stable at the final follow-up (9.0 ± 1.1 PD, p = 0.32). All patients were suppressors and had nil stereopsis pre-operatively, all of them developed fusion and a different degree of stereopsis [276 ± 284 arcseconds (Range 80-800)]. A surgical approach based on the angle of strabismus for near could obtain satisfactory ocular alignment without consecutive exotropia in children with partially accommodative esotropia wearing full refractive correction, with a manifest deviation for distance <10 PD and a higher misalignment for near, at least for 6 months after surgery.

Clarifying the effect of refractive errors and stereopsis on traumatic dental injuries in childhood.

Visual acuity and stereopsis both play an important role in developing posture and balance in children. The aim of this study was to investigate whether children with traumatic dental injuries (TDI) have abnormal stereopsis, due to a reduction in visual acuity, compared to children with good dental health. A total of 140 participants (75 with traumatic dental injuries resulting from falls and crashes, and 65 age-matched controls without dental trauma) were enrolled in this prospective, cross-sectional study. The participants underwent complete dental and ophthalmologic examinations. After the ophthalmologic examination, the stereo acuities were assessed by a Titmus stereo test at 40cm. Titmus test scores were significantly worse in the TDI group (mean score 252.46±629.12seconds of arc) compared to the control group (mean score 56±27.39seconds of arc) (P<.05). The percentage of subjects with abnormal Titmus test scores was higher in the TDI group (28%) than in the control group (3.1%). The mean anisometropia value was 3.03±2.37 D and 0.55±0.41 D in the TDI group and the control group, respectively (P<.001). The severity of anisometropia correlated with the degree of stereopsis (r=.83, P<.01). The presence of abnormal stereopsis may lead to postural instability which can lead to traumatic dental injuries. The prevalence of abnormal stereopsis in children with TDI was higher than in children with good binocular vision and stereopsis.

Clinical features and surgical outcomes of acute acquired comitant esotropia

Objective: To investigate the clinical features and surgical outcomes of patients with acute acquired concomitant esotropia (AACE) type Ⅱ(AACE-Ⅱ) and type Ⅲ (AACE-Ⅲ). Methods: Retrospective case series analysis. Medical records of consecutive patients who underwent strabismus surgery for AACE-Ⅱ and AACE-Ⅲ in Shandong Provincial Hospital affiliated to Shandong University between January 2011 and June 2016 with a minimum follow-up time of 3 months were collected. Each patient underwent a complete ophthalmological and orthoptic examination to exclude esotropia resulting from other reasons, and a systemic assessment to exclude AACE related to intracranial and systemic diseases. Surgical procedures were determined according to the esodeviations measured at distance and near and the different dominant eye of patients. A successful surgical alignment was defined as the distant and near deviation in the primary gaze within 8 prism diopters (PD) of orthophoria and no diplopia. Results: Twenty-nine patients were enrolled in this study, including 17 males and 12 females. The mean age of the patients was 22.14±15.13 years (range, 5-63 years). The median corrected visual acuity (LogMAR) of patients with AACE-Ⅱwas 0 (range, 0.22 to 0), and that of patients with AACE-Ⅲ was 0 (range, 0.10 to 0). The median esodeviation of patients with AACE-Ⅱ at distance was 35 PD (range, 10 to 55 PD), and that at near was 35 PD (range, 20 to 60 PD). The median esodeviation of patients with AACE-Ⅲ at distance was 30 PD (range, 12 to 50 PD), and that at near was 30 PD (range, 6 to 50 PD). When tested with the red filter test preoperatively, all the patients had an uncrossed horizontal diplopia with the same distance in left and right lateral fixations. With a mean follow-up time of 12.0±12.6 months, of all the 29 patients, 24 patients (83%) achieved successful surgical alignment after one surgery, and 5 patients (17%) were undercorrected or had recurrence, in whom 4 were successfully aligned after repeated surgery (performed at a mean of 3.5 months after the first surgery) and 1 was treated with the Fresnel press-on prism. At the last follow-up, of all the 28 patients successfully aligned, 20 (71%) regained bifoveal fusion, 8 (29%) regained peripheral fusion, 17 (61%) regained normal stereopsis (stereoacuity ≤60"), and 11 regained a certain degree of stereopsis (stereoacuity 80"-400"). The constituent ratio of biocular central fusion and peripheral fusion in patients with AACE-Ⅱ had no significant difference from patients with AACE-Ⅲ (χ(2)=0.235, P>0.05), and the constituent ratio of central stereopsis, macular stereopsis, and peripheral stereopsis in patients with AACE-Ⅱ had no significant difference from patients with AACE-Ⅲ (χ(2)=0.762, P>0.05). Conclusions: All patients exhibited the typical features of AACE, which included an acute onset of diplopia and comitant esotropia, a wide range of onset age of the patients, normal corrected visual acuity and ocular movements, a mean moderate level of esodeviation with a wide range, and a good binocular potential. According to the esodeviations measured at distance and near and the different dominant eye of patients, good oculomotor alignment and perceptual outcomes may be obtained in patients with AACE-Ⅱand AACE-Ⅲ. (Chin J Ophthalmol, 2017, 53: 908-916).

Quantitative Analysis of the Effects of a Bangerter Filter on Gross Stereopsis in Experimental Models of Reduced Visual Acuity.

Although a 0.3 Bangerter filter, which reduces visual acuity, is frequently used for treating moderate amblyopia, the effects on gross stereopsis are not well known. This study quantitatively evaluated whether gross stereopsis is degraded by a Bangerter filter. Seven healthy subjects (median age: 29 years) participated in this psychophysical study. Targets with crossed disparities of 1°, 2°, 3°, 4°, and 5° were randomly presented on a three-dimensional television display. The subjects indicated the point at which the targets popped out from the television screen (matching method). The distance from the screen to the point was defined as the degree of stereopsis. This experiment was performed with and without a 0.3 Bangerter filter. The corrected monocular visual acuities were decreased to about 20/63 by the filter in all subjects. No significant difference was observed for any of the disparities (1°-5°), between the degree of stereopsis visualized with and without filters for either the dominant or the non-dominant eye. The degree of stereopsis was not degraded by the reduced visual acuity induced by the use of 0.3 Bangerter filters. In this regard, the use of 0.3 Bangerter filters may be considered safer than occlusion eye patches for the patients with normal binocular vision.

Postoperative Change in Ocular Torsion in Intermittent Exotropia: Relationship with Postoperative Surgical Outcomes.

The aim of this study was to determine whether objective ocular torsion in intermittent exotropia (IXT) changes after recession surgery, and to evaluate the relationship between change in ocular torsion and clinical parameters in IXT. Sixty patients between 3 and 14 years of age underwent lateral rectus (LR) recession for IXT. Digital fundus photographs were obtained from both eyes of each subject and the disc-foveal angle (ocular torsion) was calculated using image software. We compared the preoperative and postoperative amount of ocular torsion, and analyzed the correlation between the difference in ocular torsion (DOC) and clinical parameters including age, duration of strabismus, stereoacuity, amount of preoperative exodeviation, and mean dose response. We categorized the patients according to DOC value: positive DOC value as group 1, and negative DOC value as group 2. A correlation between ocular torsion dominance and fixation preference was also investigated using the Kappa test. The mean ocular torsion was 15.8 ± 4.6 degrees preoperatively and 13.7 ± 5.1 degrees postoperatively. Compared with preoperative values, the mean ocular torsion showed a significant decrease after LR recession (p<0.001), and a greater preoperative ocular torsion was significantly associated with the amount of DOC (r = 0.37, p<0.001). Degree of stereopsis, mean dose-response, and postoperative exodeviation were significantly different between group 1 (positive DOC) and group 2 (negative DOC) (p<0.001, 0.030, and 0.001 respectively). The Kappa test showed that there was a significant correlation between the dominance of ocular torsion and fixation preference (p = 0.020). Therefore, change in ocular torsion after LR recession can be a useful supplementary indicator for evaluating the degree of fusional control and for predicting postoperative surgical response in IXT.

Sensory eye balance in surgically corrected intermittent exotropes with normal stereopsis.

Surgery to align a deviated or strabismic eye is often done for both functional as well as cosmetic reasons. Although amblyopia is often an impediment to regaining full binocularity in strabismics in general, intermittent exotropes, because their deviation is intermittent, have no amblyopia and some degree of stereopsis. Binocular function, including a balanced ocular dominance, could be expected to be normal after surgical correction if normal levels of stereopsis and visual acuity are postsurgically achieved. Here we used a binocular phase combination paradigm to quantitatively assess the ocular dominance in a group of surgically corrected intermittent exotropes who have normal stereo and visual acuity as defined clinically. Interestingly, we found significant interocular imbalance (balance point < 0.9) in most of the surgically treated patients (8 out 10) but in none of the controls. We conclude that the two eyes may still have a residual sensory imbalance in surgically corrected strabismus even if stereopsis is within normal limits. Our study opens the possibility that a further treatment aimed at re-balancing the ocular dominance might be necessary in surgically treated intermittent exotropia to provide more efficient binocular processing in the long term.

The relationship between preoperative and postoperative near stereoacuities and surgical outcomes in intermittent exotropia

AimsTo classify patients with intermittent exotropia (IXT) according to the level of near stereopsis, evaluate postoperative stereoacuity and assess the surgical outcomes among groups.MethodsThe records of 137 patients with IXT...

Dissociated vertical deviation in patients with intermittent exotropia

To determine whether the age of strabismus onset and the degree of stereopsis are related to the development of dissociated vertical deviation (DVD) in patients with intermittent exotropia and to describe the characteristics of DVD in patients with intermittent exotropia and DVD. Retrospective record review of patients with (1) intermittent exotropia with DVD; (2) infantile esotropia with DVD; and (3) intermittent exotropia without DVD. Age of strabismus onset, stereopsis, strabismus measurements, and the response of DVD to the Bielschowsky head-tilt test were compared among the three groups. Fifty-two children with intermittent exotropia and DVD were identified. In patients with intermittent exotropia with DVD and intermittent exotropia without DVD group, the mean age of strabismus onset was 12.7 months and 28.9 months, respectively (p = 0.03), and mean stereopsis was 147 arcsec and 65 arcsec (p = 0.02). In patients with intermittent exotropia with DVD and infantile esotropia with DVD, the mean amount of DVD was 9.7(Delta) and 17.2(Delta), respectively (p < 0.01). Bielschowsky head-tilt test showed an increase of DVD on ipsilateral head tilt in 91% and 63.3%, respectively. Intermittent exotropia with DVD is characterized by earlier onset of strabismus and worse stereopsis, suggesting that these factors may be related to the development of DVD in patients with intermittent exotropia. Unlike DVD in infantile esotropia, DVD in intermittent exotropia was smaller in amount and demonstrated a more uniform response to the Bielschowsky head-tilt test.

The association between nonstrabismic anisometropia, amblyopia, and subnormal binocularity

Purpose To determine if thresholds exist for the development of amblyopia and subnormal binocularity with various types of anisometropia and to compare these with existing guidelines for the treatment or observation of anisometropia. Design The records of all previously untreated patients evaluated for isolated refractive error during a 42-month period were reviewed to assess the association between anisometropia, amblyopia, and subnormal binocularity. Participants Three hundred sixty-one (361) patients with anisometropia and 50 nonanisometropic control participants, examined over a 42-month period, with no history of treatment for refractive error, amblyopia, or other ocular pathologic characteristics were evaluated. Methods Uncorrected visual acuity in each eye, monofixation response, and degree of stereopsis were recorded for each patient. Patients with unequal or subnormal uncorrected visual acuity were retested with cycloplegic refraction. If the visual acuity was still abnormal, patients were retested while wearing spectacles. Main outcome measures Degree and type of anisometropia were compared with incidence and severity of amblyopia and subnormal binocularity. Results Spherical myopic anisometropia (SMA) of more than 2 diopters (D) or spherical hypermetropic anisometropia (SHA) of more than 1 D results in a significant increase in the incidence of amblyopia and decrease in binocular function when compared with nonanisometropic patients ( P = 0.05). Increasing levels of SMA and SHA beyond these thresholds result in increased incidence and severity of amblyopia. Cylindrical myopic anisometropia (CMA) or cylindrical hyperopic anisometropia (CHA) of more than 1.5 D results in a significant increase in amblyopia and a decrease in binocular function ( P = 0.05). Levels of CMA and CHA more than 1.5 D result in an increased incidence and severity of amblyopia. Conclusions This study supports existing guidelines for the treatment or observation of anisometropia and characterizes the association between the type and degree of anisometropia and the incidence and severity of amblyopia and subnormal binocularity.

Acquired central fusional disruption with spontaneous recovery

Acquired loss of central fusion occurs most frequently after severe head trauma. It has also been described as a result of disruption of binocular function by unilateral deprivation from a cataract and following mid-brain injury due to vascular lesions, tumours or abscess. Symptoms include diplopia in all positions of gaze associated with a squint of variable size. Occasionally some patients experience a spontaneous, partial recovery of fusion, which may be manipulated with strabismus surgery to minimise diplopia. Recovery of fusion may take months or even a few years to occur. We present two cases of patients who lost fusion but later regained it spontaneously with a high degree of stereopsis. Neither patient required strabismus surgery. In the first case, fusion was lost following a severe head injury which resulted in unconsciousness and a unilateral vitreous haemorrhage. The second case followed the removal of a long-standing, unilateral cataract.

Binocular Disparity and Stereopsis Obtained under White Light with a Diffraction Grating

Abstract Simple experimental conditions for imaging through diffraction gratings are considered involving binocular disparity and fusion of different images. Two-wavelength images obtained when observing with suitable colour filters naturally produce the perception of a single virtual object with different degrees of stereopsis.

Interocular transfer of the motion after-effect in normal and stereoblind observers

The extent of interocular transfer of the motion after-effect was measured in 4 stereoblind subjects and in 19 subjects having varying degrees of stereopsis. Stereoblind individuals failed completely to show any interocular transfer of this after-effect, while subjects with good stereopsis exhibited between 55 and 82 percent transfer (mean 73 percent). Furthermore, normal subjects who manifested a clear eye dominance tended to show greater transfer from the dominant to the nondominant eye than vice versa. Individuals who either had a history of a strabismus or possessed some other early impediment to clear binocular vision tended to show less transfer. Overall there was a significant positive correlation of 0.75 between the extent of interocular transfer and the subject's stereoacuity. It is argued that the extent of interocular transfer of this after-effect provides a measure of the proportion of the total number of visual cortical neurons that are binocular. Thus stereoblind humans, who show no transfer whatsoever may, like cats and monkeys deprived of concordant binocular visual input early in life, suffer from a lack of binocular neurons.

Some observations on divergence excess.

Many excellent papers^1-9have been written recently concerning the type and amount of surgery to be done for the more perfect correction of intermittent exotropia. To satisfy my own curiosity and to add further clarity to this field, I reviewed 451 consecutive cases of exotropia done on the ward service of the Massachusetts Eye and Ear Infirmary. These included: (1) overcorrected esotropias, (2) constant exotropias, (3) alternating exotropias, (4) exotropias which have as their basis reduced vision and resultant deviation, and (5) intermittent exotropias with (<i>a</i>) convergence insufficiency and (<i>b</i>) divergence excess. Only in this last category was it possible to find any definite relationship between type and amount of surgery and the degree of stereopsis. <h3>Method of Selection of Cases</h3> In Category 5, intermittent exotropia, I have used Costenbader's classification³for delineating divergence excess, and only this will be covered in this paper. The characteristics for divergence