The Analysis of Ocular Deviations between Dominant and Non-dominant Eye Using Video-oculography in Intermittent Exotropia

PURPOSE: To measure and analyze ocular deviations between dominant and non-dominant eyes using video-oculography (VOG) in intermittent exotropia. METHODS: Fourteen subjects who were diagnosed with intermittent exotropia from July 2017 to July 2018 with age of 5 or more, visual acuity of 20/30 or better and corrected visual acuity of 20/25 or more and difference in vision of both eyes of 1 line or less on Snellen optotype were included. The subjects were asked to fixate on a black-on-white optotype at 1 m, which subtended a visual angle of 50 minutes of arc. The video files and data about ocular deviations were obtained using VOG with alternate cover test. We analyzed angles of ocular deviations in dominant and non-dominant eyes. RESULTS: Among the 14 subjects in this study, the mean age were 7.6 ± 1.7 (range 5–9 years). Seven of 14 subjects had the right eye dominance. Six of the 14 subjects were men. There was no significant difference of ocular deviations between the dominant and non-dominant eyes in VOG (p = 0.167). Additionally, there was no significant difference of the values of VOG when one eye was exodeviated or re-fixated (p = 0.244), when both eyes were deviated, and when both eyes were re-fixated (p = 0.195, 0.637). CONCLUSIONS: In this study, there was no significant difference of ocular deviations between the dominant and non-dominant eyes, between when an eye was exodeviated or fixated using VOG. Therefore, it may not be a problem even if alternate prism cover test is performed in any eye in intermittent exotropia of more than 50 prism diopter without amblyopia or refraction abnormality that could affect the uncorrected visual acuity.

Two Cases of Myasthenia Gravis Showing Fatigibility Presenting with Decreased Gain of Smooth Pursuit / 대한평형의학회지

Myasthenia gravis (MG) is an autoimmune disease caused by autoantibodies to the acetylcholine receptors of the neuromuscular junction characterized by weakness and abnormal fatigability of the muscles. Therefore, the diagnosis of MG depends on the recognition of this distinctive pattern of fatigable weakness. Previous studies presented the diagnostic efficacy of saccadic eye movements in patients with ocular MG. We here in report 2 patients of ocular MG showing the fatigue effects during repetitive sustained smooth pursuit, and the effects of the administration of edrophonium on myasthenic smooth pursuit. Changes in smooth pursuits reflecting peripheral and secondary central mechanisms were demonstrated.

Numerical study on adjusting parameters to improve gaze estimation using planar approximations from electro-oculogram signal voltage ratios

Gaze or eye movements are used as a communication interface in daily life. Herein, we developed a simple method for gaze estimations based on planar approximations of voltage ratios calculated from multiple electro-oculogram signals not affected by drift phenomena, which decrease accuracy. Subsequently, we conducted simulations using an eyeball battery model and investigated the effects of adjusting electrode arrangements, determination coefficients for planar approximations of voltage ratios, and threshold values for angles between simultaneous linear equations, to improve the estimation accuracy and decreased the number of required electrodes. Numerical experiments were used to identify arrangements of six electrodes with errors that were approximately 5° less than those of nine-electrode L-shaped arrangements, indicating improved estimation accuracy with fewer electrodes.

Use of Video-oculography in the Diagnosis of Superior Oblique Myokymia

PURPOSE: Superior oblique myokymia is intermittent spontaneous contractions of the superior oblique muscle presenting as rapid and small-amplitude intorsions and depressions of the eye. The authors report a case of superior oblique myokymia that was objectively and quantitatively diagnosed with slit lamp examination and video-oculography and completely resolved with medical treatment. CASE SUMMARY: A 44-year-old woman presented with a seven-year history of intermittent oscillopsia which continued for few seconds. She had no history of head trauma or systemic ocular disease, and the anterior segment and fundus examination were unremarkable. Right eye intorsion lasting for a few seconds as detected by slit lamp examination. Eye movements were recorded using video-oculography, which showed a torsional nystagmus of 5 to 10 degrees with 2 to 5 vertical components in the right eye. Based on these findings, the patient was diagnosed with superior oblique myokymia. The patient was prescribed topical timolol ophthalmic solution, one drop twice per day, but the symptoms persisted. Timolol ophthalmic solution was stopped and replaced with carbamazepine, 200 mg twice a day, which resolved her symptoms. CONCLUSIONS: Slit lamp examination and video-oculography can be used as objective and quantitative diagnostic tools in order to confirmed a diagnosis and lead to proper treatment.

Phase portrait analysis of eye movement waveforms in congenital nystagmus eyes / 中华实验眼科杂志

Background The characteristics of eye movement waveforms in congenital nystagmus eyes is so complicated that the time-series waveform can hardly demonstrate the oscillational kinetic property of the eye movement of nystagmus,which is not convenient for the clinical diagnosis and evaluation.The eye movement system is a nonlinear feedback control system,and phase portrait analysis is a useful method in describing the characteristics of movement in a nonlinear system.Objective This study was to establish the phase portrait analysis method of the eye movement waveforms in congenital nystagmus eyes and provide a new technique for the clinical diagnosis and evaluation of congenital nystagmus.Methods A prospective series-case observational study was performed.This study complied with the Declaration of Helsinki and was approved by Ethic Commission of Tianjin Eye Hospital.Written informed consent was obtained from each patient before examination.Twenty-five patients with congenital nystagmus were enrolled and received examination of video-oculography (VOG) in Tianjin Eye Hospital from April 2012 to February 2013,including 12 patients with congenital motor nystagmus (CMN) and 13 patients with latent nystagmus (LN).The VOG data were format-converted and processed by a Matlab routine.VOG-based phase portraits of eye movement cycles were drawn and related parameters were measured from the phase portraits for further analysis and comparison.Main measurement indexes were cycle position shift (CPS),slow phase peak velocity (SPV),standardized slow-phase peak (SSPV),fast phase peak velocity (FPV) and standardized fast-phase peak velocity (SFPV).Two principal types of waveforms,increasing-velocity type and decreasing-velocity type were compared.Results The phase portraits of the waveforms of congenital nystagmus were cycles of reciprocating trajectories.The slow phases were in dense ribbon region,and the fast phases were in sparse annular region,and all the trajectories travelled in clockwise.The CPS,SPV and FPV of increasing-velocity type were (4.646 ± 1.565),(223.821 ± 114.049),(767.481 ±263.560) ° per second,respectively.The CPS,SPV and FPV of decreasing-velocity type were (9.373 ±4.189),(357.531 ± 154.300) and (1 148.706 ±541.362) ° per second,respectively.The SPVs and FPVs of both increasing-velocity type and decreasing-velocity type showed strong correlation with CPS,respectively (the increasing-velocity type:rSPV-CPS =0.685,P=0.000;rFPV-CPS =0.680,P=0.000;the decreasing-velocity type rSPV-CPS =0.783,P =0.000;rFPV-CPS =0.803,P =0.000).FPVs were significantly larger than SPVs in both types of waveforms (t =6.558,P =0.000;t =5.068,P =0.000).The SSPV of increasing-velocity type was (48.062 ± 15.365) ° per second,which was slightly larger than (41.099± 17.027) ° per second of decreasing-velocity type,with no significant difference between them (t=1.070,P=0.296).The SFPV of increasing-velocity type was (171.186±47.825)° per second,which was larger than (125.317-±38.266)° per second of decreasing-velocity type,showing a significant difference between them (t =2.658,P =0.014).Conclusions Phase portraits can visualize the cyclically dynamic features of congenital nystagmus in a direct way.It facilitates the measurement of eye movement amplitude,speed and other parameters.The phase portrait analysis method provides a novel useful tool in the clinical diagnosis and treatment efficacy evaluation of congenital nystagmus.

Two Cases of Congenital Ocular Motor Apraxia Associated With Cerebellar Vermian Dysplasia

Congenital ocular motor apraxia is a rare syndrome characterized by rotational head thrusts that attempt to compensate for the lack of voluntary eye movements. We describe the clinical, oculographic and magnetic resonance imaging features of two children with congenital ocular motor apraxia.

Asociación entre la alteración de los movimientos oculares sacádicos y la esquizofrenia: un estudio de casos y controles / Altered Saccadic Eye Movements in Schizophrenia: A Case-Control Study

Contexto: Los pacientes con diagnóstico de esquizofrenia presentan alteraciones en los movimientos oculares, principalmente en los movimientos sacádicos; ésto se plantea como un marcador biológico de la enfermedad. Objetivo: Evaluar la alteración de los movimientos oculares sacádicos como marcadores biológicos en sujetos con diagnóstico de esquizofrenia. Metodología: Estudio de casos y controles en 50 pacientes con diagnóstico de esquizofrenia y 48 controles sanos emparejados por edad y sexo. Se diseñó un instrumento electrónico y un software para realizar la prueba electrooculográfi ca y analizar las señales mediante algoritmos computacionales. A cada participante se le realizó una entrevista psiquiátrica estructurada, un electrooculograma y una evaluación optométrica. Se caracterizó la señal electrooculográfi ca, identifi cando las regiones donde ocurrían las sacadas o saltos. De estas regiones se obtuvieron valores para los parámetros: amplitud, duración, ganancia, latencia y velocidad pico. Se hizo un análisis estadístico de variación con el método ANOVA de una vía o con el método no parámetrico de Kruskal-Wallis, cuando los datos no tenían distribución normal. Resultados: Se observaron diferencias estadísticamente signifi cativas entre ambos grupos únicamente para el parámetro “latencia” en amplitudes visuales mayores de 45 grados y en la realización del movimiento antisacádico para amplitudes visuales de 10 y 20 grados, patrones reportados por otros investigadores.

Context: Altered saccadic eye movements are considered biological markers of schizophrenia. Objective: To evaluate alterations of saccadic eye movements as biological markers in subjects diagnosed with schizophrenia. Methodology: Case-Control study in 50 patients diagnosed with schizophrenia and 48 healthy control subjects paired by age and gender. An electronic device and software were designed to perform the electro-oculographic test and to analyze the signals using computational algorithms. A structured psychiatric interview, an electro-oculogram and an optometric test were performed on all the participants. The electro-oculographic signal was then characterized, identifying the regions where the saccadic leaps occurred. Within these regions the parameters amplitude, duration, gain, latency and peak velocity were measured. A statistical analysis was performed using the one way ANOVA or the Kruskall-Wallis when the data did not have a normal distribution. Results: Statistically signifi cant differences were observed between both groups only for the “latency” in visual amplitudes larger than 45 degrees and in the anti-saccadic movement in visual amplitudes between 10 and 20 degrees, patterns that have been reported by other researchers.

Eye Movements Recording with Video-oculography (VOG)

The measurement of eye movements in three dimensions is an important tool to investigate the human oculomotor system. When compared with the conventional electro-nystagmography (ENG) and scleral search coil system (SSCS), the video-oculography (VOG) has a higher accuracy and is a more comfortable and reliable method for the 3D-measurement of human eye movements.

Clinical and Oculographic Findings of X-linked Congenital Nystagmus in Three Korean Families

BACKGROUND AND PURPOSE: Congenital nystagmus (CN) is an ocular oscillation that usually manifests during early infancy. Typical features of CN include bilateral, conjugate, uniplanar, and usually horizontal eye movements, a null position, increased oscillation during fixation, and decreased amplitude during convergence. Our purposes were description and analysis of clinical and oculomotor findings of patients with X-linked familial CN. METHODS: We describe the clinical and oculographic features of five patients from three families with X-linked CN. Three-dimensional video-oculography disclosed various patterns of CN and variable degrees of gaze-holding deficits and visual impairments. RESULTS: The features of CN varied even in patients from the same family. Head tilt, strabismus, reversal of optokinetic nystagmus, and impairments of the vestibulo-ocular reflex, smooth pursuits, and saccades were frequent findings. CONCLUSIONS: The intra- and interfamilial diversities imply that heredity plays a secondary role in determining the clinical phenotypes and waveforms of CN.

Clinical and Oculographic Findings of X-linked Congenital Nystagmus in Three Korean Families

BACKGROUND AND PURPOSE: Congenital nystagmus (CN) is an ocular oscillation that usually manifests during early infancy. Typical features of CN include bilateral, conjugate, uniplanar, and usually horizontal eye movements, a null position, increased oscillation during fixation, and decreased amplitude during convergence. Our purposes were description and analysis of clinical and oculomotor findings of patients with X-linked familial CN. METHODS: We describe the clinical and oculographic features of five patients from three families with X-linked CN. Three-dimensional video-oculography disclosed various patterns of CN and variable degrees of gaze-holding deficits and visual impairments. RESULTS: The features of CN varied even in patients from the same family. Head tilt, strabismus, reversal of optokinetic nystagmus, and impairments of the vestibulo-ocular reflex, smooth pursuits, and saccades were frequent findings. CONCLUSIONS: The intra- and interfamilial diversities imply that heredity plays a secondary role in determining the clinical phenotypes and waveforms of CN.

Novel Mutation in FRMD7 Gene in X-linked Congenital Nystagmus

BACKGROUND AND OBJECTIVES: Congenital nystagmus (CN) is an ocular oscillation that usually manifests during early infancy. To report a novel mutation in FERM domain containing 7 (FRMD7) gene in a Korean family with CN. MATERIALS AND METHODS:Genomic DNA was prepared from peripheral blood leukocytes and direct sequencing of the entire coding and adjacent intronic regions was performed to detect sequence variation of FRMD7 gene, where mutations were found recently in patients with familial CN. The family showed an X-linked pattern of inheritance without father-to-son transmission. RESULTS: Three family members with CN exhibited two sequence variations which were a novel mutation (c. 875T>C; Leu292Pro) and a polymorphism (c. 1403G>A; Arg468His, dbSNP rs#6637934). The proband was hemizygous for both variations and his mother and maternal grandmother were heterozygous carriers. CONCLUSION: This study provides an additional evidence for mutations in FRMD7 as a common cause of X-linked CN and expands its mutation spectrum.

Convergence-Retraction Nystagmus: Analysis with 3-dimensional Oculography

BACKGROUND AND OBJECTIVES:Convergence-retraction oscillations are rhythmic or arrhythmic jerks of dysjunctive eye movements associated with backward displacement of the eyeballs during the convergence phase. Oscillations in convergence-retraction oscillations have been proposed to be consisted of opposed adducting saccades immediately followed by slow abducting glissades without latency. However, dynamic characteristics of convergence oscillations accompanying retraction have not been studied, and pathomechanism of these eye movements remains to be elucidated. This study was to get insights on the pathomechanisms of convergence-retraction oscillations by using 3-dimensional recording of eye movements. In particular, we intended to clarify whether the nystagmus originates from instability of vergence eye movement or of saccades. MATERIALS AND METHOD:Seven consecutive patients with convergence-retraction oscillations were recruited. All the patients received full neurological and neuro-ophthalmological evaluation by the senior author. Some of the patients underwent 3-dimensional recordings of convergence-retraction oscillations with video-oculography or magnetic search coil technique. RESULTS:Wave forms of convergence-retraction oscillations were varied. The onset of convergent eye movements was either synchronous or asynchronous between both eyes. The initial directions of eye movement was same (conjugate) or opposite (disjunctive). In some, vergence eye movements occurred only in one eye (unilateral). Convergence phase of one eye was commonly consisted of multiple steps while the other eye attained final position with a single step. The following divergent eye movements commonly overshoot the orbital midposition and were followed by correcting convergent eye movements. The velocity-amplitude relationship of convergent eye movements, which was analyzed in typical pairs of vergence oscillations, did not differ between both eyes. Divergent eye movements are slower than convergent eye movements. The both convergent and divergent eye movements were slower than the microsaccades of similar amplitudes. CONCLUSION:Quantitative analyses of convergence-retraction oscillations revealed various patterns of wave forms. The amplitude-velocity relationships of the disjunctive eye movements suggest that the slowed saccades may be due to co-contraction of the agonist and antagonist, or due to enhanced vergence eye movements by the accompanying saccades.

Voluntary Nystagmus

PURPOSE: We evaluated the clinical manifestations of voluntary nystagmus in three patients and verified the efficacy of video-oculography as a diagnostic tool to differentiate voluntary nystagmus from congenital or latent nystagmus. METHODS: Meticulous history taking and neuro-ophthalmologic examination were performed for three patients with voluntary nystagmus. Video-oculography was also performed in one patient. RESULTS: All of the three patients were young men in military service. Neuro-ophthalmologic examination was normal in all three patients, except for shaking of the eyes. Video-oculography in one patient showed 5~6 Hz pendular oscillation with an amplitude of 7~15 degrees and a peak velocity of 345.4 deg/sec, verifying that the oscillatory eye movement was composed of saccades and was not a nystagmus. CONCLUSIONS: In differentiating between voluntary and congenital nystagmus, video-oculography as well as history taking and neuro-ophthalmologic examination were very helpful.

Ocular Search Pattern during Line Bisection Task in Normal Subjects

BACKGROUND: The study of ocular search pattern in normal subjects and patients with hemispatial neglect may help understand spatial cognition. However, only a few studies are available that investigated ocular search pattern even in normal controls. The present study was to investigate ocular search pattern of normal subjects during line bisection task. METHODS: Nine normal subjects (6 men and 3 women with mean age of 21.8+/-4.2 years) were requested to fix their eyes on the midpoint of the line that was presented on the monitor. Lines for bisection were varied according to the location (center, right-sided or left-sided) and length (short or long) and each subject performed 6 trials (one trial/condition). Horizontal eye movements were recorded using an infrared video-oculography and were analyzed in terms of the range and the direction of eye movements. RESULTS: Average range of fixation during line bisection was 20.1% of entire length that corresponded middle portion of the line. There was no directional preference in searching the line during line bisection task. CONCLUSIONS: We expected that normal subjects overtly look at both ends of the line before they bisect the line. On the contrary, they seem to use a strategy such that they directly go to the middle part of the line and then make fine adjustment while looking at both ends of line covertly. (J Korean Neurol Assoc 19(2):96~101, 2001)

Ocular Search Pattern during Line Bisection Task in Normal Subjects

BACKGROUND: The study of ocular search pattern in normal subjects and patients with hemispatial neglect may help understand spatial cognition. However, only a few studies are available that investigated ocular search pattern even in normal controls. The present study was to investigate ocular search pattern of normal subjects during line bisection task. METHODS: Nine normal subjects (6 men and 3 women with mean age of 21.8+/-4.2 years) were requested to fix their eyes on the midpoint of the line that was presented on the monitor. Lines for bisection were varied according to the location (center, right-sided or left-sided) and length (short or long) and each subject performed 6 trials (one trial/condition). Horizontal eye movements were recorded using an infrared video-oculography and were analyzed in terms of the range and the direction of eye movements. RESULTS: Average range of fixation during line bisection was 20.1% of entire length that corresponded middle portion of the line. There was no directional preference in searching the line during line bisection task. CONCLUSIONS: We expected that normal subjects overtly look at both ends of the line before they bisect the line. On the contrary, they seem to use a strategy such that they directly go to the middle part of the line and then make fine adjustment while looking at both ends of line covertly. (J Korean Neurol Assoc 19(2):96~101, 2001)

Electrophysiologic Finding of Retinitis Pigmentosa Inversus and Differential Diagnosis from Peripapillary Choroidal Dystrophy

The authors found 3 cases of retinitis pigmentosa inversus who had characteristics that age of onset is between fifth and sixth decade, retinal lesion was seen around the optic disc and along the retinal vascular arcade, margin is discrete, and peripheral retina is morphologically normal. The authors performed routine ophthalmic examination, fluorescein angiography, electroretinography, electro-oculography. Fluorescein angiogram of retinitis pigmentosa inversus showed diffuse hyperfluoresce due to retinal pigment epithelium atrophy and partical hypofluoreseenee due to choriocapillary atrophy. Characteristic electroretinogram findings were moderate decrease of rod function and mild decrease of cone function. The authors also experienced 1 cases of peripapillary choroidal dystrophy and could differentiate it from retinitis pigmentosa inversus. Peripapillary choroidal dystrophy showed similar that of retinitis pigmentosa inversus in electroretinogram test, but showed diffuse and typical hypofluo rescence due to choriocapillary and retinal pigment epithelium atrophy according to the retinal lesion.

Simulated Nystagmus Blockage Syndrome

Manifest latent nystagmus (MLN) combined with esotropia may be confused with the nystagmus blockage syndrome (NBS), so the NBS may be overdiagnosed. The NBS is similar to MLN in the characteristics of the nystagmus and the clinical features, thus two diseases must be differentiated. In order to differentiate the MLN with esotropia from the NBS, accurate calibration of slow phase of nystagmus is essential with the aid of electro-oculography (EOG). With EOG recording, authors report a case of MLN associated with esotropia which may be misdiagnosed as the NBS.

A Case of Atypical Latent Nystagmus Associated with Infantile Nystagmus

The latent nystagmus seems to be absent when both eyes are open, but on covering one eye, bilateral jerky nystagmus is evoked with the fast phase toward the uncovered eye. The confirmed diagnosis of latent nystagmus can be made with the aid of the Electro-oculography (EOG). On EOG recording, we experienced a case of latent nystagmus in light, which showed the characteristics of infantile nystagmus in darkness.