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Sharma P, Tibrewal S, Singh PK, Ganesh S. Efficacy of anti-suppression therapy in improving binocular vision in children with small-angle Esotropia. JOURNAL OF OPTOMETRY 2024; 17:100490. [PMID: 38061140 PMCID: PMC10750105 DOI: 10.1016/j.optom.2023.100490] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Revised: 08/21/2023] [Accepted: 08/30/2023] [Indexed: 12/29/2023]
Abstract
PURPOSE To evaluate the efficacy of anti-suppression exercises in children with small-angle esotropia in achieving binocular vision. METHODS A retrospective review of patients aged 3-8 years who underwent anti-suppression exercises for either monocular or alternate suppression between January 2016 and December 2021 was conducted. Patients with esotropia less than 15 prism diopters (PD) and visual acuity ≥ 6/12 were included. Patients with previous intra-ocular surgery or less than three-month follow-up were excluded. Success was defined as the development of binocular single vision (BSV) for distance, near, or both (measured clinically with either the 4 prism base out test or Worth four dot test) and maintained at two consecutive visits. Qualified success was defined as the presence of diplopia response for both distance and near. Additionally, improvement in near stereo acuity was measured using the Stereo Fly test. RESULTS Eighteen patients with a mean age of 5.4 ± 1.38 years (range 3-8 years) at the time of initiation of exercises were included in the study. The male female ratio was 10:8. The mean best corrected visual acuity was 0.18 LogMAR unit(s) and the mean spherical equivalent was +3.8 ± 0.14 diopters (D). The etiology of the esotropia was fully accommodative refractive esotropia (8), microtropia (1), post-operative infantile esotropia (4), partially accommodative esotropia (1), and post-operative partially accommodative esotropia (4). Patients received either office-based, home-based, or both modes of treatment for an average duration of 4.8 months (range 3-8). After therapy, BSV was achieved for either distance or near in 66.6 % of patients (95 % CI = 40.03-93.31 %). Binocular single vision for both distance and near was seen in 50 % of children. Qualified success was observed in 38.46% of patients. Persistence of suppression was observed in one patient (5.5 %). Near stereopsis improved to 200 s of arc or more in 60% of the patients. The mean esotropia reduced from 5.7 ± 4.0 PD for distance and 6.2 ± 4.66 PD for near to 2.7 ± 2.4 PD and 3.38 ± 4.7 PD respectively, at the last follow-up (p-value 0.004 and 0.006). Failure of therapy was noticed after six months of follow-up in the child with infantile esotropia. CONCLUSION Anti-suppression exercises may be beneficial to improve binocular vision functions in children with small-angle esotropias of variable etiologies. Recurrence of suppression after cessation of therapy is possible, warranting regular follow up.
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Affiliation(s)
- Preeti Sharma
- Department of Pediatric Ophthalmology, Strabismus and Neuro-ophthalmology, Dr. Shroff's Charity Eye Hospital, Daryaganj, New Delhi 110002, India.
| | - Shailja Tibrewal
- Department of Pediatric Ophthalmology, Strabismus and Neuro-ophthalmology, Dr. Shroff's Charity Eye Hospital, Daryaganj, New Delhi 110002, India
| | - Prem Kumar Singh
- Department of Pediatric Ophthalmology, Strabismus and Neuro-ophthalmology, Dr. Shroff's Charity Eye Hospital, Daryaganj, New Delhi 110002, India
| | - Suma Ganesh
- Department of Pediatric Ophthalmology, Strabismus and Neuro-ophthalmology, Dr. Shroff's Charity Eye Hospital, Daryaganj, New Delhi 110002, India
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Peli E, Jung JH. Review: Binocular double vision in the presence of visual field loss. J Vis 2024; 24:13. [PMID: 38899959 PMCID: PMC11193068 DOI: 10.1167/jov.24.6.13] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2023] [Accepted: 03/13/2024] [Indexed: 06/21/2024] Open
Abstract
Binocular double vision in strabismus is marked by diplopia (seeing the same object in two different directions) and visual confusion (seeing two different objects in the same direction). In strabismus with full visual field, the diplopia coexists with visual confusion across most of the binocular field. With visual field loss, or with use of partial prism segments for field expansion, the two phenomena may be separable. This separability is the focus of this review and offers new insights into binocular function. We show that confusion is necessary but is not sufficient for field expansion. Diplopia plays no role in field expansion but is necessary for clinical testing of strabismus, making such testing difficult in field loss conditions with confusion without diplopia. The roles of the three-dimensional structure of the real world and the dynamic of eye movements within that structure are considered as well. Suppression of one eye's partial view under binocular vision that develops in early-onset (childhood) strabismus is assumed to be a sensory adaption to diplopia. This assumption can be tested using the separation of diplopia and confusion.
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Affiliation(s)
- Eli Peli
- Schepens Eye Research Institute of Massachusetts Eye and Ear, Department of Ophthalmology, Harvard Medical School, Boston, MA, USA
| | - Jae-Hyun Jung
- Schepens Eye Research Institute of Massachusetts Eye and Ear, Department of Ophthalmology, Harvard Medical School, Boston, MA, USA
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Pur DR, Sivakumar GK, Bursztyn LLCD, Iordanous Y, de Ribaupierre S. Strabismus outcomes in pediatric patients undergoing disconnective hemispheric surgery for intractable epilepsy: a systematic review. CANADIAN JOURNAL OF OPHTHALMOLOGY 2023:S0008-4182(23)00244-2. [PMID: 37640228 DOI: 10.1016/j.jcjo.2023.07.021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2022] [Revised: 06/09/2023] [Accepted: 07/31/2023] [Indexed: 08/31/2023]
Abstract
BACKGROUND Children undergoing hemispheric surgery for intractable seizures are susceptible to visual complications including strabismus. This systematic review aims to investigate the rates and characteristics of strabismus development after hemispheric surgery and evaluate clinical implications for ophthalmologic care. METHODS A systematic search of MEDLINE, EMBASE, Cochrane, PsychINFO, and Web of Science databases was performed from database inception to May 2022. Included articles referred to strabismus outcomes in pediatric populations after hemispherectomy or hemispherotomy. Reviews and non-English-language publications were excluded. Risk of bias was assessed using Joanna Briggs Institute critical appraisal tools. Demographic data and characteristics of strabismus were extracted and tabulated. RESULTS Of 41 articles identified, 10 studies consisting of 384 pediatric participants (48% females) and age at surgery between 6 months and 16 years were included. Preoperative strabismus rates ranged between 3% and 56%, whereas postoperative rates ranged between 38% and 100%. With respect to the site of hemispheric surgery, contralateral exodeviation was the most common (16%-67%; n = 7) and then ipsilateral exodeviation (16%-56%; n = 2), whereas ipsilateral esodeviation was infrequent (4%-9%; n = 3). CONCLUSIONS Contralateral exotropia and ipsilateral esotropia may occur after hemispheric surgery and may have the potential to be field expanding. Concerns regarding negative social reactions should be balanced with the risk of visual field reduction and (or) diplopia by strabismus surgery. Higher-quality articles with large, homogeneous, and well-described populations (i.e., complete pre- and postoperative ophthalmologic assessments) are required to establish the risks and rates of strabismus development after hemispheric surgery.
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Affiliation(s)
- Daiana R Pur
- Schulich School of Medicine and Dentistry, Western University, London, ON.
| | - Gayathri K Sivakumar
- Department of Ophthalmology, Schulich School of Medicine and Dentistry, Western University, London, ON
| | - Lulu L C D Bursztyn
- Department of Ophthalmology, Schulich School of Medicine and Dentistry, Western University, London, ON; Department of Clinical Neurological Sciences, Western University, London, ON
| | - Yiannis Iordanous
- Department of Ophthalmology, Schulich School of Medicine and Dentistry, Western University, London, ON
| | - Sandrine de Ribaupierre
- Department of Clinical Neurological Sciences, Western University, London, ON; Brain and Mind Institute, Western University, London, ON; Children's Health Research Institute, Western University, London, ON
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Ma MML, Scheiman M. Divergence excess and basic exotropia types of intermittent exotropia: a major review. Part 1: prevalence, classification, risk factors, natural history and clinical characteristics. Strabismus 2023; 31:97-128. [PMID: 37489263 DOI: 10.1080/09273972.2023.2227681] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 07/26/2023]
Abstract
INTRODUCTION Intermittent exotropia (IXT) is a common form of strabismus. It is an outward deviation of one eye typically when viewing at distance. Symptoms include, but are not limited to double vision, eyes feeling tired, excessive blinking, and reduced quality of life. Its clinical characteristics are distinctive from other types of strabismus. This paper provides a comprehensive review of prevalence, classification, risk factors, natural history and clinical characteristics of the divergence excess and basic exotropia types of IXT. METHODS Search strategies involving combination of keywords including intermittent exotropia, exotropia, divergences excess, basic exotropia, prevalence, incidence, classification, terminology, risk factor, natural history, observation, angle of deviation, control, control score, symptom, quality of life, suppression, anomalous retinal correspondence, AC/A, accommodative convergence/accommodation, accommodative convergence, convergence, accommodation, vergence, incomitance and vertical were used in Medline. All English articles from 1900/01/01 to 2020/09/01 were reviewed. The reference list of the identified article was also checked for additional relevant article. Studies focused on animal model or strabismus associated with neurologic disorder or injury were excluded. RESULTS The estimated prevalence of IXT in children ranges from 0.1% to 3.7%. Hypoxia at birth and being female are potential risk factors of IXT. Using validated measures of control, multicenter prospective studies showed that the rate of conversion from IXT to constant exotropia is low. The angle of deviation is the most reported outcome measure in studies of IXT. It is often used to represent the severity of the condition and has been suggested as one of the four core outcomes for studies of the surgical management of IXT. Control of exodeviation is one of the four suggested core outcomes for study of surgery of IXT and is considered the main parameter of disease severity. Several validated tools for quality of life score are available to evaluate the subjective severity of IXT. DISCUSSION We reviewed the prevalence, classification, risk factors, natural history and clinical characteristics of the divergence excess and basic exotropia types of IXT. Further research into these areas, especially its clinical characteristics (e.g. suppression, dual retinal correspondence), will increase our understanding of this condition and potentially lead to better management of this common form of strabismus.
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Affiliation(s)
- Martin Ming-Leung Ma
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou
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Economides JR, Dilbeck MD, Gentry TN, Horton JC. Ambulatory Monitoring With Eye Tracking Glasses to Assess the Severity of Intermittent Exotropia. Am J Ophthalmol 2023; 250:120-129. [PMID: 36681174 DOI: 10.1016/j.ajo.2023.01.014] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Revised: 01/11/2023] [Accepted: 01/12/2023] [Indexed: 01/19/2023]
Abstract
PURPOSE To explore the utility of eye tracking glasses in patients with intermittent exotropia as a means for quantifying the occurrence of exotropia, defined as the percentage of time that the eyes are misaligned. DESIGN Prospective observational study. METHODS Eye tracking glasses were used to obtain 68 recordings in 44 ambulatory patients with a history of intermittent exotropia. Vergence angle was monitored for up to 12 hours to document the occurrence of exotropia. RESULTS Intermittent exotropia was present in 31 of 44 patients. They had a mean exotropia of 19.3 ± 5.3° and a mean occurrence of 40% (range 3-99%). There was a moderate correlation between the magnitude of exotropia and its occurrence (r = 0.59). In 13 patients the occurrence of exotropia was <1%; they were deemed to have an exophoria only. In 35 of 44 cases, families reported an occurrence of intermittent exotropia greater than that measured by the eye tracking glasses. CONCLUSIONS Eye tracking glasses may be a useful tool for quantifying the severity of intermittent exotropia and for defining more precisely its clinical features.
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Affiliation(s)
- John R Economides
- From the Department of Ophthalmology, University of California, San Francisco, San Francisco, California, USA
| | - Mikayla D Dilbeck
- From the Department of Ophthalmology, University of California, San Francisco, San Francisco, California, USA
| | - Thomas N Gentry
- From the Department of Ophthalmology, University of California, San Francisco, San Francisco, California, USA
| | - Jonathan C Horton
- From the Department of Ophthalmology, University of California, San Francisco, San Francisco, California, USA..
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Dichoptic visual field mapping of suppression in exotropia with homonymous hemianopia. J AAPOS 2021; 25:276.e1-276.e6. [PMID: 34587558 PMCID: PMC8665098 DOI: 10.1016/j.jaapos.2021.05.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Revised: 04/23/2021] [Accepted: 05/17/2021] [Indexed: 11/23/2022]
Abstract
BACKGROUND The purpose of this study was to investigate which portions of the visual scene are perceived by each eye in an exotropic subject with acquired hemianopia. The pattern of suppression is predictable from knowledge of how suppression scotomas are organized in exotropic subjects with intact visual fields. METHODS Dichoptic perimetry was performed by having a subject wear red/blue goggles while fixating a cross that was either red or blue. Red, blue, or purple spots were presented briefly at peripheral locations. The subject's identification of the spot color revealed which eye was perceptually engaged at any given location in the visual fields. RESULTS A 17-year-old female with a history of exotropia was evaluated after rupture of a right parietal arteriovenous malformation. Dichoptic perimetry showed a left homonymous hemianopia. All stimuli to the right of the right fovea's projection point were perceived via the right eye. Stimuli between the foveal projection points, which were separated horizontally by the 20° exotropia, were perceived by the left eye. CONCLUSIONS Perception of the visual scene is shared by the eyes in hemianopia and exotropia. Suppression occurs only in the peripheral temporal retina of the eye contralateral to the brain lesion, regardless of which eye is engaged in fixation. Although exotropia expands the binocular field of vision in hemianopia, it is probably not an adaptive response, even when it develops after hemianopia.
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Economides JR, Dilbeck MD, Adams DL, Horton JC. Interocular suppression in primary visual cortex in strabismus: impact of staggering the presentation of stimuli to the eyes. J Neurophysiol 2021; 126:1101-1111. [PMID: 34432999 DOI: 10.1152/jn.00275.2021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Diplopia (double vision) in strabismus is prevented by suppression of the image emanating from one eye. In a recent study conducted in two macaques raised with exotropia (an outward ocular deviation) but having normal acuity in each eye, simultaneous display of stimuli to each eye did not induce suppression in V1 neurons. Puzzled by this negative result, we have modified our protocol to display stimuli in a staggered sequence, rather than simultaneously. Additional recordings were made in the same two macaques, following two paradigms. In trial type 1, the receptive field in one eye was stimulated with a sine-wave grating while the other eye was occluded. After 5 s, the occluder was removed and the neuron was stimulated for another 5 s. The effect of uncovering the eye, which potentially exposed the animal to diplopia, was quantified by the peripheral retinal interaction index (PRII). In trial type 2, the receptive field in the fixating eye was stimulated with a grating during binocular viewing. After 5 s, a second grating appeared in the receptive field of the nonfixating eye. The impact of the second grating, which had the potential to generate visual confusion, was quantified by the receptive field interaction index (RFII). For 82 units, the mean PRII was 0.48 ± 0.05 (0.50 = no suppression) and the mean RFII was 0.46 ± 0.08 (0.50 = no suppression). These values suggest mild suppression, but the modest decline in spike rate registered during the second epoch of visual stimulation might have been due to neuronal adaptation, rather than interocular suppression. In a few instances neurons showed unequivocal suppression, but overall, these recordings did not support the contention that staggered stimulus presentation is more effective than simultaneous stimulus presentation at evoking interocular suppression in V1 neurons.NEW & NOTEWORTHY In strabismus, double vision is prevented by interocular suppression. It has been reported that inhibition of neuronal firing in the primary visual cortex occurs only when stimuli are presented sequentially, rather than simultaneously. However, these recordings in alert macaques raised with exotropia showed, with rare exceptions, little evidence to support the concept that staggered stimulus presentation is more effective at inducing interocular suppression of V1 neurons.
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Affiliation(s)
- John R Economides
- Program in Neuroscience, Department of Ophthalmology, University of California, San Francisco, California
| | - Mikayla D Dilbeck
- Program in Neuroscience, Department of Ophthalmology, University of California, San Francisco, California
| | - Daniel L Adams
- Program in Neuroscience, Department of Ophthalmology, University of California, San Francisco, California
| | - Jonathan C Horton
- Program in Neuroscience, Department of Ophthalmology, University of California, San Francisco, California
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Economides JR, Adams DL, Horton JC. Interocular Suppression in Primary Visual Cortex in Strabismus. J Neurosci 2021; 41:5522-5533. [PMID: 33941649 PMCID: PMC8221600 DOI: 10.1523/jneurosci.0044-21.2021] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Revised: 04/22/2021] [Accepted: 04/27/2021] [Indexed: 11/21/2022] Open
Abstract
People with strabismus acquired during childhood do not experience diplopia (double vision). To investigate how perception of the duplicate image is suppressed, we raised two male monkeys with alternating exotropia by disinserting the medial rectus muscle in each eye at age four weeks. Once the animals were mature, they were brought to the laboratory and trained to fixate a small spot while recordings were made in primary visual cortex (V1). Drifting gratings were presented to the receptive fields of 500 single neurons for eight interleaved conditions: (1) right eye monocular; (2) left eye monocular; (3) right eye's field, right eye fixating; (4) right eye's field, left eye fixating; (5) left eye's field, right eye fixating; (6) left eye's field, left eye fixating; (7) both eyes' fields, right eye fixating; (8) both eyes' fields, left eye fixating. As expected, ocular dominance histograms showed a monocular bias compared with normal animals, but many cells could still be driven via both eyes. Overall, neuronal responses were not affected by switches in ocular fixation. Individual neurons exhibited binocular interactions, but mean population indices indicated no net interocular suppression or facilitation. Even neurons located in cortex with reduced cytochrome oxidase (CO) activity, representing portions of the nasal visual field where perception is suppressed during binocular viewing, showed no net inhibition. These data indicate that V1 neurons do not appear to reflect strabismic suppression and therefore the elimination of diplopia is likely to be mediated at a higher cortical level.SIGNIFICANCE STATEMENT In patients with strabismus, images fall on non-corresponding points in the two retinas. Only one image is perceived, because signals emanating from the other eye that convey the duplicate image are suppressed. The benefit is that diplopia is prevented, but the penalty is that the visual feedback required to adjust eye muscle tone to realign the globes is eliminated. Here, we report the first electrophysiological recordings from the primary visual cortex (V1) in awake monkeys raised with strabismus. The experiments were designed to reveal how perception of double images is avoided.
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Affiliation(s)
- John R Economides
- Program in Neuroscience, Department of Ophthalmology, University of California, San Francisco, California 94143
| | - Daniel L Adams
- Program in Neuroscience, Department of Ophthalmology, University of California, San Francisco, California 94143
| | - Jonathan C Horton
- Program in Neuroscience, Department of Ophthalmology, University of California, San Francisco, California 94143
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Basics of Understanding Strabismus. Strabismus 2019. [DOI: 10.1007/978-981-13-1126-0_1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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García-García MÁ, Belda JI, Schargel K, Santos MJ, Ruiz-Colecha J, Rey C, García-García P, Mompean B. Optical Coherence Tomography in Children With Microtropia. J Pediatr Ophthalmol Strabismus 2018; 55:171-177. [PMID: 29384563 DOI: 10.3928/01913913-20171026-01] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Accepted: 08/08/2017] [Indexed: 11/20/2022]
Abstract
PURPOSE To assess whether optical coherence tomography (OCT) could be useful for detecting and documenting fixation in patients with microtropia. METHODS Retinal fixation observation was performed using spectral-domain OCT on amblyopic children with microtropia. The position between the retinal fixation point and the anatomical fovea was measured, in microns, using the system software tools. Only patients with a high level of cooperation, OCT scan quality signal of 7 or better, and visual acuity of 0.70 logarithm of the minimum angle of resolution (logMAR) or worse in the amblyopic eye were included. RESULTS A total of 25 patients were included: 15 with microtropia (study group) and 10 without tropia and with foveal fixation and stereopsis (control group). In the study group, microtropia was previously diagnosed in 67% of cases through the cover test, and was predominantly in the left eye (73%). The average visual acuity of the sound eye was 0.03 decimal and 0.18 logMAR in the amblyopic eye. The microtropia was 3.73 ± 3.34 prism diopters and eccentric fixation (387 ± 199 µm) with OCT was observed in all cases except one. Eccentricity was predominantly in the superonasal quadrant (57%). Both eyes in the control group and the contralateral eyes of the study group showed foveal fixation. CONCLUSIONS OCT can play an important role in the diagnosis and measurement of eccentric fixation in eyes with microtropia, providing high sensitivity. [J Pediatr Ophthalmol Strabismus. 2018;55(3):171-177.].
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Normal Topography and Binocularity of the Superior Colliculus in Strabismus. J Neurosci 2017; 38:173-182. [PMID: 29133438 DOI: 10.1523/jneurosci.2589-17.2017] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2017] [Revised: 10/30/2017] [Accepted: 11/08/2017] [Indexed: 02/03/2023] Open
Abstract
In subjects with alternating strabismus, either eye can be used to saccade to visual targets. The brain must calculate the correct vector for each saccade, which will depend on the eye chosen to make it. The superior colliculus, a major midbrain center for saccade generation, was examined to determine whether the maps serving each eye were shifted to compensate for strabismus. Alternating exotropia was induced in two male macaques at age 1 month by sectioning the tendons of the medial recti. Once the animals grew to maturity, they were trained to fixate targets with either eye. Receptive fields were mapped in the superior colliculus using a sparse noise stimulus while the monkeys alternated fixation. For some neurons, sparse noise was presented dichoptically to probe for anomalous retinal correspondence. After recordings, microstimulation was applied to compare sensory and motor maps. The data showed that receptive fields were offset in position by the ocular deviation, but otherwise remained aligned. In one animal, the left eye's coordinates were rotated ∼20° clockwise with respect to those of the right eye. This was explained by a corresponding cyclorotation of the ocular fundi, which produced an A-pattern deviation. Microstimulation drove the eyes accurately to the site of receptive fields, as in normal animals. Single-cell recordings uncovered no evidence for anomalous retinal correspondence. Despite strabismus, neurons remained responsive to stimulation of either eye. Misalignment of the eyes early in life does not alter the organization of topographic maps or disrupt binocular convergence in the superior colliculus.SIGNIFICANCE STATEMENT Patients with strabismus are able to make rapid eye movements, known as saccades, toward visual targets almost as gracefully as subjects with normal binocular alignment. They can even exercise the option of using the right eye or the left eye. It is unknown how the brain measures the degree of ocular misalignment and uses it to compute the appropriate saccade for either eye. The obvious place to investigate is the superior colliculus, a midbrain oculomotor center responsible for the generation of saccades. Here, we report the first experiments in the superior colliculus of awake primates with strabismus using a combination of single-cell recordings and microstimulation to explore the organization of its topographic maps.
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Maxfield SD, Hatt SR, Leske DA, Jung JH, Holmes JM. Factors associated with atypical postoperative drift following surgery for consecutive exotropia. J AAPOS 2017; 21:360-364. [PMID: 28867397 PMCID: PMC5734656 DOI: 10.1016/j.jaapos.2017.07.201] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Revised: 07/13/2017] [Accepted: 07/14/2017] [Indexed: 10/18/2022]
Abstract
PURPOSE To evaluate the associations of clinical and surgical factors with atypical postoperative drift following surgery for consecutive exotropia. METHODS A total of 66 patients with consecutive exotropia (≥10Δ at distance), after historical surgery for esotropia were retrospectively identified at a tertiary medical center. All patients underwent unilateral lateral rectus recession (on adjustable suture) with medial rectus advancement and/or resection. Immediate postoperative target angle was 4Δ-10Δ of esotropia at distance, anticipating mild postoperative exodrift. Actual postoperative drift was calculated as change in distance deviation from immediately postadjustment to 6 weeks. Typical drift was defined as 0Δ-9Δ of exodrift. Excessive exodrift was defined as ≥10Δ. Esodrift was defined as 1Δ or more. Univariate and multiple logistic regression analyses were performed to evaluate for associations with a wide range of clinical and surgical factors. RESULTS Overall there was a median exodrift (4Δ, quartiles 0Δ-10Δ). Of the 66 patients, 18 (27%) showed excessive exodrift; 15 (23%), esodrift. In multiple logistic analyses, larger preoperative distance exodeviation was associated with excessive exodrift (P = 0.01), and non-normal medial rectus attachment status (abnormal [stretched scar, pseudo-tendon], attached to pulley, or behind pulley) was associated with esodrift (P = 0.02). CONCLUSIONS Approximately half of patients show atypical drift following unilateral surgery for consecutive exotropia, with larger preoperative distance exodeviation associated with exodrift and non-normal medial rectus muscle status with esodrift. Knowing these associations may help when counseling patients regarding surgical outcomes.
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Affiliation(s)
| | - Sarah R Hatt
- Department of Ophthalmology, Mayo Clinic, Rochester, Minnesota
| | - David A Leske
- Department of Ophthalmology, Mayo Clinic, Rochester, Minnesota
| | - Jae Ho Jung
- Department of Ophthalmology, Mayo Clinic, Rochester, Minnesota; Department of Ophthalmology, Pusan National University Yangsan Hospital, Yangsan, South Korea
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Bridge H. Effects of cortical damage on binocular depth perception. Philos Trans R Soc Lond B Biol Sci 2017; 371:rstb.2015.0254. [PMID: 27269597 PMCID: PMC4901448 DOI: 10.1098/rstb.2015.0254] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/10/2015] [Indexed: 12/20/2022] Open
Abstract
Stereoscopic depth perception requires considerable neural computation, including the initial correspondence of the two retinal images, comparison across the local regions of the visual field and integration with other cues to depth. The most common cause for loss of stereoscopic vision is amblyopia, in which one eye has failed to form an adequate input to the visual cortex, usually due to strabismus (deviating eye) or anisometropia. However, the significant cortical processing required to produce the percept of depth means that, even when the retinal input is intact from both eyes, brain damage or dysfunction can interfere with stereoscopic vision. In this review, I examine the evidence for impairment of binocular vision and depth perception that can result from insults to the brain, including both discrete damage, temporal lobectomy and more systemic diseases such as posterior cortical atrophy. This article is part of the themed issue ‘Vision in our three-dimensional world’.
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Affiliation(s)
- Holly Bridge
- FMRIB Centre, Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DU, UK
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Economides JR, Adams DL, Horton JC. Capturing the Moment of Fusion Loss in Intermittent Exotropia. Ophthalmology 2017; 124:496-504. [PMID: 28081943 PMCID: PMC5685669 DOI: 10.1016/j.ophtha.2016.11.039] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Revised: 11/29/2016] [Accepted: 11/29/2016] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To characterize eye movements made by patients with intermittent exotropia when fusion loss occurs spontaneously and to compare them with those induced by covering 1 eye and with strategies used to recover fusion. DESIGN Prospective study of a patient cohort referred to our laboratory. PARTICIPANTS Thirteen patients with typical findings of intermittent exotropia who experienced frequent spontaneous loss of fusion. METHODS The position of each eye was recorded with a video eye tracker under infrared illumination while fixating on a small central near target. MAIN OUTCOME MEASURES Eye position and peak velocity measured during spontaneous loss of fusion, shutter-induced loss of fusion, and recovery of fusion. RESULTS In 10 of 13 subjects, the eye movement made after spontaneous loss of fusion was indistinguishable from that induced by covering 1 eye. It reached 90% of full amplitude in a mean of 1.75 seconds. Peak velocity of the deviating eye's movement was highly correlated for spontaneous and shutter-induced events. Peak velocity was also proportional to exotropia amplitude. Recovery of fusion was more rapid than loss of fusion, and often was accompanied by interjection of a disconjugate saccade. CONCLUSIONS Loss of fusion in intermittent exotropia is not influenced by visual feedback. Excessive divergence tone may be responsible, but breakdown of alignment occurs via a unique, pathological type of eye movement that differs from a normal, physiological divergence eye movement.
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Affiliation(s)
- John R Economides
- Department of Ophthalmology, University of California, San Francisco, San Francisco, California
| | - Daniel L Adams
- Department of Ophthalmology, University of California, San Francisco, San Francisco, California; Center for Mind/Brain Sciences, The University of Trento, Trento, Italy
| | - Jonathan C Horton
- Department of Ophthalmology, University of California, San Francisco, San Francisco, California.
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Economides JR, Adams DL, Horton JC. Normal correspondence of tectal maps for saccadic eye movements in strabismus. J Neurophysiol 2016; 116:2541-2549. [PMID: 27605534 DOI: 10.1152/jn.00553.2016] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2016] [Accepted: 09/06/2016] [Indexed: 11/22/2022] Open
Abstract
The superior colliculus is a major brain stem structure for the production of saccadic eye movements. Electrical stimulation at any given point in the motor map generates saccades of defined amplitude and direction. It is unknown how this saccade map is affected by strabismus. Three macaques were raised with exotropia, an outwards ocular deviation, by detaching the medial rectus tendon in each eye at age 1 mo. The animals were able to make saccades to targets with either eye and appeared to alternate fixation freely. To probe the organization of the superior colliculus, microstimulation was applied at multiple sites, with the animals either free-viewing or fixating a target. On average, microstimulation drove nearly conjugate saccades, similar in both amplitude and direction but separated by the ocular deviation. Two monkeys showed a pattern deviation, characterized by a systematic change in the relative position of the two eyes with certain changes in gaze angle. These animals' saccades were slightly different for the right eye and left eye in their amplitude or direction. The differences were consistent with the animals' underlying pattern deviation, measured during static fixation and smooth pursuit. The tectal map for saccade generation appears to be normal in strabismus, but saccades may be affected by changes in the strabismic deviation that occur with different gaze angles.
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Affiliation(s)
- John R Economides
- Beckman Vision Center, Program in Neuroscience, University of California, San Francisco, California; and
| | - Daniel L Adams
- Beckman Vision Center, Program in Neuroscience, University of California, San Francisco, California; and.,Center for Mind/Brain Sciences, The University of Trento, Trento, Italy
| | - Jonathan C Horton
- Beckman Vision Center, Program in Neuroscience, University of California, San Francisco, California; and
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Agaoglu S, Agaoglu MN, Das VE. Motion Information via the Nonfixating Eye Can Drive Optokinetic Nystagmus in Strabismus. Invest Ophthalmol Vis Sci 2016; 56:6423-32. [PMID: 26444723 DOI: 10.1167/iovs.15-16923] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Strabismic patients can perceptually suppress information from one eye to avoid double vision. However, evidence from prior studies shows that some parts of the visual field of the deviated eye are not suppressed. Our goal here was to investigate whether motion information available only to the deviated eye can be utilized by the oculomotor system to drive eye movements. METHODS Binocular eye movements were acquired in two exotropic monkeys in a dichoptic viewing task in which the fixating eye viewed a stationary spot and the deviated eye viewed a 10° × 10° stationary patch that contained a drifting grating stimulus moving at 10°/s to the right or left for 20 seconds. Spatial location and contrast of the grating were systematically varied in subsequent trials. For each trial, mean slow-phase velocity of the optokinetic nystagmus (OKN) elicited by grating motion was calculated. RESULTS We found that OKN responses can be elicited by a motion stimulus presented to the foveal region of the deviated eye. Optokinetic nystagmus magnitude varied depending on which eye was viewing the drifting grating and correlated well with fixation preference and fixation stability (indicators of amblyopia). The magnitude of OKN increased for increased relative contrast of the motion stimulus compared to the fixation spot. CONCLUSIONS Our results show that motion information available only to the deviated eye can drive optokinetic eye movements. We conclude that the brain has access to visual information from portions of the deviated eye (including the fovea) in strabismus that it can use to drive eye movements.
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17
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Abstract
In strabismus, potentially either eye can inform the brain about the location of a target so that an accurate saccade can be made. Sixteen human subjects with alternating exotropia were tested dichoptically while viewing stimuli on a tangent screen. Each trial began with a fixation cross visible to only one eye. After the subject fixated the cross, a peripheral target visible to only one eye flashed briefly. The subject's task was to look at it. As a rule, the eye to which the target was presented was the eye that acquired the target. However, when stimuli were presented in the far nasal visual field, subjects occasionally performed a "crossover" saccade by placing the other eye on the target. This strategy avoided the need to make a large adducting saccade. In such cases, information about target location was obtained by one eye and used to program a saccade for the other eye, with a corresponding latency increase. In 10/16 subjects, targets were presented on some trials to both eyes. Binocular sensory maps were also compiled to delineate the portions of the visual scene perceived with each eye. These maps were compared with subjects' pattern of eye choice for target acquisition. There was a correspondence between suppression scotoma maps and the eye used to acquire peripheral targets. In other words, targets were fixated by the eye used to perceive them. These studies reveal how patients with alternating strabismus, despite eye misalignment, manage to localize and capture visual targets in their environment.
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18
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Koenraads Y, van der Linden DCP, van Schooneveld MMJ, Imhof SM, Gosselaar PH, Porro GL, Braun KPJ. Visual function and compensatory mechanisms for hemianopia after hemispherectomy in children. Epilepsia 2014; 55:909-17. [PMID: 24754334 DOI: 10.1111/epi.12615] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/02/2014] [Indexed: 11/30/2022]
Affiliation(s)
- Yvonne Koenraads
- Department of Ophthalmology; University Medical Center Utrecht; Utrecht The Netherlands
| | | | - Monique M. J. van Schooneveld
- Department of Pediatric Psychology; Sector Neuropsychology; University Medical Center Utrecht; Utrecht The Netherlands
| | - Saskia M. Imhof
- Department of Ophthalmology; University Medical Center Utrecht; Utrecht The Netherlands
| | - P. H. Gosselaar
- Department of Neurosurgery; Brain Center Rudolf Magnus; University Medical Center Utrecht; Utrecht The Netherlands
| | - Giorgio L. Porro
- Department of Ophthalmology; University Medical Center Utrecht; Utrecht The Netherlands
| | - Kees P. J. Braun
- Department of Pediatric Neurology; Brain Center Rudolf Magnus; University Medical Center Utrecht; Utrecht The Netherlands
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Agaoglu MN, LeSage SK, Joshi AC, Das VE. Spatial patterns of fixation-switch behavior in strabismic monkeys. Invest Ophthalmol Vis Sci 2014; 55:1259-68. [PMID: 24508786 DOI: 10.1167/iovs.13-13460] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Patients with strabismus perceptually suppress information from one eye to avoid double vision. Mechanisms of visual suppression likely lead to fixation-switch behavior wherein the subject acquires targets with a specific eye depending on target location in space. The purpose of this study was to investigate spatial patterns of fixation-switch behavior in strabismic monkeys. METHODS Eye movements were acquired in three exotropic and one esotropic monkey in a binocular viewing saccade task. Spatial patterns of fixation were analyzed by calculating incidence of using either eye to fixate targets presented at various gaze locations. RESULTS Broadly, spatial fixation patterns and fixation-switch behavior followed expectations if a portion of the temporal retina was suppressed in exotropia and a portion of the nasal retina was suppressed in esotropia. Fixation-switch occurred for horizontal target locations that were approximately greater than halfway between the lines of sight of the foveating and strabismic eyes. Surprisingly, the border between right eye and left eye fixation zones was not sharply defined and there was a significant extent (>10°) over which the monkeys could acquire a target with either eye. CONCLUSIONS We propose that spatial fixation patterns in strabismus can be accounted for in a decision framework wherein the oculomotor system has access to retinal error information from each eye and the brain chooses between them to prepare a saccade. For target locations approximately midway between the two foveae, strength of retinal error representations from each eye is almost equal, leading to trial-to-trial variability in choice of fixating eye.
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Holgado S. Diplopia after strabismus surgery. THE AMERICAN ORTHOPTIC JOURNAL 2012; 62:5-8. [PMID: 23002467 DOI: 10.3368/aoj.62.1.5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The presence of diplopia is an undesirable result following strabismus surgery. There are a variety of scenarios where diplopia exists prior to strabismus surgery, and, after surgery, has either been alleviated or decreased to a magnitude amenable to prism correction. In other cases, the patient does not experience diplopia prior to the strabismus surgery, but there exists a definite risk of diplopia after the surgery. In the current review, I examine the literature to help determine the incidence of diplopia after strabismus surgery.
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Affiliation(s)
- Sandra Holgado
- Duke University Eye Center, Durham, North Carolina 27710, USA.
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21
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Serrano-Pedraza I, Clarke MP, Read JCA. Single vision during ocular deviation in intermittent exotropia. Ophthalmic Physiol Opt 2011; 31:45-55. [PMID: 21158884 DOI: 10.1111/j.1475-1313.2010.00805.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Intermittent exotropia is a common oculomotor anomaly where one eye intermittently deviates outwards. Patients with this type of strabismus are often not aware of the exodeviation and do not usually experience diplopia. In this review, we discuss what is known about the cortical mechanisms which achieve single vision during exodeviation in this condition, and highlight some outstanding questions.
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Affiliation(s)
- Ignacio Serrano-Pedraza
- Institute of Neuroscience, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK.
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Abstract
Four children developed homonymous hemianopia, exotropia with the deviating eye pointing in the direction of the field defect, and a face turn toward the side of the defect following complete third cranial nerve palsy after brain tumor resection, an in utero middle cerebral artery infarction, nonaccidental head trauma, and a hemispherectomy for an intractable seizure disorder. We present evidence that the exotropia and face turn are part of an adaptive mechanism to increase the useful visual field.
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Zivotofsky AZ, Schrader SR. Temporal influences on retinal correspondence: ocular motor findings in paradoxical spatial projection. Optom Vis Sci 2004; 81:712-7. [PMID: 15365391 DOI: 10.1097/01.opx.0000144750.73094.2b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
Abstract
BACKGROUND Paradoxical diplopia is a condition in which objective eye position contradicts subjective localization in visual space. The term "paradoxical" is usually reserved for instances when known sensory adaptations cannot explain the contradiction. The development of this condition begins with infantile or childhood strabismus, followed by the development of a common sensory adaptation, anomalous retinal correspondence (ARC). ARC causes a reduction in the subjective angle of strabismus compared with the objective angle, and in its completed form the subjective angle decreases to zero. There is no "adaptive" mechanism that would increase the subjective angle such that it would be greater than the objective. In cases of treatment by corrective surgery, the anatomically based motor correction leads to a contradiction between eye position and binocular perception. In this event, the objective angle is less than the subjective, and the result is a paradoxical perception. We encountered a 25-year-old woman who experiences paradoxical localization on cover testing in the absence of a manifest strabismus and with no previous surgical intervention. METHODS Using a magnetic search coil technique, we evaluated eye movements during fixation, smooth pursuit, saccades, and during cover test conditions to determine how these eye movements correlated to the subjective perception in space. RESULTS Although smooth pursuit and saccades were normal, there were two elements during cover test that could explain the paradoxical projection. One was the phenomenon that during the cover test the paradoxical projection appeared only when the eye was covered for >4 s. The second was that there was a regression from the full exophoria position toward the midline while the eye was under cover that correlated with a possible paradoxical projection situation. DISCUSSION ARC, usually associated with a beneficial sensorimotor adaptation, can express itself as a detrimental sensorimotor manifestation. Paradoxical perception also can exist without previous surgical intervention and without the influence of prisms and instrumentation such as the synoptophore. Further studies are indicated to explore the sensorimotor feedback mechanism between eye position and spatial perception.
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Affiliation(s)
- Ari Z Zivotofsky
- Gonda Brain Science Program, Bar Ilan University, Ramat Gan, Israel
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