[Congenital or infantile strabismus]

Surgical outcomes and occurrence of associated vertical strabismus during a 10-year follow-up in patients with infantile esotropia

Purpose:

Authors analyzed long-term surgical outcomes of infantile esotropia and the occurrence of associated strabismus, inferior oblique overaction (IOOA), and dissociated vertical deviation (DVD). Clinical factors related to the occurrence of IOOA and DVD in patients with infantile esotropia were also evaluated.

Methods:

Medical records of patients with infantile esotropia, who underwent surgery between 1995 and 2008, were reviewed retrospectively. Included patients were followed for at least 10 years. The incidence and age at development of IOOA and DVD were analyzed. To evaluate predisposing factors for developing IOOA or DVD, patients were divided into two groups: those with infantile esotropia only (group A) and those who developed IOOA or DVD (group B).

Results:

A total of 122 patients were enrolled and mean follow-up period was 16.0 years (range: 10–32 years). The mean number of surgeries was 1.7 (range: 1–5), and 64 (52.5%) patients achieved optimal horizontal alignment (esotropia <10 prism diopters [PD] and orthotropia). Fifty (41.0%) patients developed IOOA at a median age of 3 years (range: 1–21 years); 54 (44.3%) developed DVD at a median age of 5 years (range: 1–25 years). Patients in group B underwent more horizontal surgeries than those in group A (P = 0.028), and favorable surgical outcomes between the two groups were not different at final visit. There were no other significant differences in clinical factors between the two groups.

Conclusion:

Approximately, 52.5% of patients achieved favorable surgical outcomes through 1.7 surgeries during the 10-year follow-up period. DVD tended to develop at a later age than IOOA, and in some cases, up to 20 years after diagnosis of infantile esotropia. To achieve favorable horizontal alignment at final visit, patients with associated vertical strabismus underwent more horizontal muscle surgeries than patients with infantile esotropia only. The presence of IOOA/DVD may affect horizontal alignment outcomes.

Vertical Optokinetic Stimulation Induces Diagonal Eye Movements in Patients with Idiopathic Infantile Nystagmus

Purpose

In patients with early ocular misalignment and nystagmus, vertical optokinetic stimulation reportedly increases the horizontal component of the nystagmus present during fixation, resulting in diagonal eye movements. We tested patients with infantile nystagmus syndrome but normal ocular alignment to determine if this crosstalk depends on strabismus.

Methods

Eye movements were recorded in seven patients with infantile nystagmus. All but one patient had normal ocular alignment with high-grade stereopsis. Nystagmus during interleaved trials of right, left, up, and down optokinetic stimulation was compared with waveforms recorded during fixation. Six patients with strabismus but no nystagmus were also tested.

Results

In infantile nystagmus syndrome, horizontal motion evoked a mostly jerk nystagmus with virtually no vertical component. A vertical optokinetic pattern produced nystagmus with a diagonal trajectory. It was not simply a combination of a vertical component from optokinetic stimulation and a horizontal component from the subject's congenital nystagmus, rather in six of seven patients, the slow-phase velocity of the horizontal component during vertical optokinetic stimulation differed from that recorded during fixation. In the six strabismus patients without nystagmus, responses to vertical optokinetic stimulation were normal.

Conclusions

In patients with congenital motor nystagmus, a vertical noise pattern drives a diagonal nystagmus. This appears to arise because of crosstalk between the vertical and horizontal components of the optokinetic system. This abnormal response to vertical stimulation is not caused by strabismus because it occurs in patients with infantile nystagmus without strabismus. Moreover, it is absent in patients with strabismus and no spontaneous nystagmus.

Is it possible to differentiate early-onset accommodative esotropia from early-onset essential esotropia?

PURPOSE

To determine the frequency of > or =2.50 diopter (D) hyperopia in infantile esotropia with onset up to the age of 6 months and by evaluating the treatment results of these cases retrospectively, to find the factors that may help to differentiate early-onset accommodative esotropia from early-onset essential esotropia.

METHODS

The charts of 256 patients with infantile esotropia were reviewed. Thirtyseven cases, with hyperopia of > or =2.50 D, no other systemic and neurologic disease, and at least 1 year of follow-up, were included in this study. The age at the start of therapy, refractive error, deviation angle, type of therapy (antiaccommodative therapy, surgery) and the presence of amblyopia, latent nystagmus, inferior oblique overaction, dissociated vertical deviation and cross-fixation were recorded for each case.

RESULTS

The prevalence of high hyperopia was found to be 14.4% (37/256) in infantile esotropia. In 18 of the cases (48.6%), antiaccommodative therapy alone was found to be adequate (Group I). In the remaining 19, although antiaccommodative therapy was found to decrease the deviation angle significantly (P<0.001), surgery was also required (Group II). Groups were compared with respect to age at the initial examination, refractive error, deviation angle, presence of amblyopia, anisometropia, and inferior oblique overaction, but no factor could be determined to predict the pure refractive ones (P>0.05). Essential infantile esotropia-associated findings did not help because they are rarely evident at the time of initial diagnosis.

CONCLUSIONS

Half of the high hyperopic infantile esotropes could be corrected fully by antiaccommodative therapy alone, while the remaining ones could also benefit significantly. It is strongly recommended to try spectacles at first in the treatment of infantile esotropia with hyperopia > or =2.5 D.

Dissociated vertical deviation and head tilts

INTRODUCTION

The association of anomalous head posture and dissociated vertical deviation does not seem to be appreciated, as evidenced by the paucity of literature linking these two conditions.

METHOD

The series describes 14 patients who had an anomalous head posture and dissociated vertical deviation. The assumed head tilts appeared to decrease the magnitude and improve the motor control of dissociated vertical deviation.

RESULTS

Twelve of 14 patients tilted their heads contralateral to the eye with the dissociated vertical deviation, or away from the eye with a larger amount of dissociated vertical deviation if the disorder was bilateral. Two patients tilted their heads to the same side as the eye with the dissociated vertical deviation. Forced head tilt-testing in the opposite direction showed an increase in the magnitude of the dissociated vertical deviation or poorer control of the deviation. Dissociated vertical deviation was not related to oblique muscle dysfunction. Peripheral fusion was demonstrated in 10 patients, as evidenced by low-grade stereopsis or Worth 4 dot fusion at near. One patient did not show any demonstrable fusion with conventional tests. Another did not show evidence of stereopsis, but Worth 4 dot testing was not performed. Two other patients were too young to cooperate with sensory testing. Anomalous head posture was controlled or minimized after the control of the dissociated vertical deviation by surgery in four patients. Two patients showed improved stereopsis after surgery for dissociated vertical deviation.

CONCLUSION

Dissociated vertical deviation should be included in the differential diagnosis of an ocular cause of head tilts. Forced contralateral head tilttesting will confirm whether dissociated vertical deviation is the cause if motor control of the dissociated vertical deviation worsens or becomes manifest rather than latent. The presence of an anomalous head posture in patients with dissociated vertical deviation can be improved with strabismus surgery.

On infantile esotropia with nystagmus in abduction

Infantile esotropia with nystagmus in abduction is characterized by early onset, jerk nystagmus in abduction, and dissociated vertical deviation, among other features. Electro-oculographic tracings present easily recognizable patterns both in saccadic and pursuit movements. Visual evoked responses are asymmetric in most cases and optokinetic nystagmus is invariably asymmetric. Visual cortex maldevelopment seems to play a major pathogenic role. Recent findings in myelomeningocele and in patients with posterior fossa tumors suggest that pathological alterations in this area may tend to induce similar anomalies in electro-oculographic and optokinetic nystagmus recordings. Posterior fossa damage or impairment is therefore suspected to be a possible causative factor in the development of infantile esotropia with nystagmus in abduction.

The prevalence of dissociated vertical deviation in patients with sensory heterotropia

PURPOSE

We reviewed 281 consecutive patients with sensory esotropia or exotropia to determine the prevalence of dissociated vertical deviation in patients with sensory strabismus.

METHODS

We reviewed the charts of all patients who received a diagnosis of sensory heterotropia or dissociated vertical deviation and who were examined at the Pediatric Ophthalmology Service at the Texas Children's Hospital between 1973 and 1992. Statistical analyses of the prevalence of dissociated vertical deviation were determined after evaluating the direction of the accompanying horizontal strabismus and examining the temporal relationship of the unilateral vision loss.

RESULTS

Dissociated vertical deviation was diagnosed in 35 patients (12.5%). It occurred more frequently in sensory esotropia (22 patients, 18.3%) than exotropia (13 patients, 8.1%) (P = .009). The age at which unilateral visual loss occurred did not influence the development of dissociated vertical deviation.

CONCLUSION

Dissociated vertical deviation in patients with acquired loss of vision does not support the contention that dissociated vertical deviation is a genetically predetermined anomaly of binocular vision.

19th annual Frank Costenbader Lecture--the origins of congenital esotropia

Congenital esotropia develops in the first 4 months of life in an infant who lacks the inborn mechanism for motor fusion. It manifests as an esotropia which is not eliminated by correction of hyperopia and occurs in an otherwise neurologically normal infant. The earliest practical time for surgery is 4 months of age. The eye is anatomically suited for surgery at this age and also, this is the earliest age that congenital esotropia can be diagnosed with confidence. The best attainable result of treatment of congenital esotropia is subnormal binocular vision. This result is more likely to be attained if infants are aligned by 18 months of age. Satisfactory alignment is produced in 80% to 85% of infants in one procedure with an appropriate bimedial rectus recession. An array of motor defects including DVD, latent nystagmus, oblique dysfunction, and A- and V-pattern appear at varying times after successful alignment. These associated findings are commonly found with, but are not unique to, congenital esotropia. The onset and clinical picture of congenital esotropia is satisfactorily explained by a theory first suggested by Worth that the strabismus is caused by an inborn defect in the motor fusion mechanism and aggravated by esotropital factors as suggested by Chavasse. In contrast to congenital esotropia, all other strabismus can be thought of as occurring on a secondary basis in a person with the inborn capacity for motor fusion, but who failed to maintain it because of conatal insurmountable strabismus (congenital third nerve palsy), who lost it because of acquired (postnatal) strabismus, who uses a strategy such as head posture alteration to retain fusion under favorable circumstances (Duane syndrome), who has intermittent strabismus with part-time suppression (X(T)), or who is maintaining alignment with nonsurgical means (refractive esotropia). For the future, I believe that advances in the management of congenital esotropia will depend on a better understanding of etiology leading to design and use of innovative nonsurgical techniques to discourage convergence and stimulate bifoveal fusion.

Horizontal transposition of the vertical rectus muscles for treatment of ocular torticollis

In most instances, a head tilt to either shoulder is caused by hypertropia or cyclotropia and responds well to conventional surgical strengthening or weakening operations on the cyclovertical muscles. Occasionally, an ocular head tilt occurs in the absence of cyclovertical strabismus, in association with congenital nystagmus or without an apparent cause. We have successfully treated four of five such patients by surgically rotating the eye(s) around the sagittal axis. This was accomplished by horizontal transposition of the vertical rectus muscles. No complications were encountered. We present this method as a viable alternative to other surgical approaches to rotate the eyes around their sagittal axis.

A reassessment of infantile esotropia. XLIV Edward Jackson memorial lecture

Essential infantile esotropia is an early acquired, not a congenital, condition, although congenital factors may favor its development between the ages of 3 and 6 months. It must be distinguished from other forms of esotropia with an onset between birth and the first six months of life. The cause of essential infantile esotropia remains unknown, but advances in our knowledge can be expected from the rapidly emerging discipline of infant psychophysics. In analyzing treatment results, a clear distinction must be made between normal, subnormal, and anomalous forms of binocular cooperation. While complete restoration of normal binocular function is rarely, if ever, achieved, anomalous binocular cooperation has many functional advantages over suppression or diplopia and should not be disturbed by overzealous treatment. Subnormal binocular vision is considered to be an optimal, microtropia a desirable, and a residual small angle heterotropia an acceptable end stage of surgical therapy. In a study of 358 surgically treated patients with a documented onset of essential infantile esotropia before age 6 months, subnormal binocular vision was present in 71 (20%), a microtropia in 25 (7%), and a small angle esotropia or exotropia in 140 (39%) of the patients. Surgical alignment before completion of the second year of life improved the chances for an optimal treatment result.(ABSTRACT TRUNCATED AT 250 WORDS)

Compensatory mechanisms in congenital nystagmus

Congenital nystagmus may occur in a manifest or latent form. Since most patients with latent nystagmus also have nystagmus with both eyes open (manifest latent nystagmus), differentiation between these two entities frequently requires electronystagmographic wave form analysis. Such analysis shows distinctive characteristics for manifest and latent or manifest latent congenital nystagmus, suggesting different origins. Several compensation mechanisms exist by which congenital nystagmus is decreased and visual acuity improved. For manifest nystagmus, these mechanisms include version or convergence innervation or a rest point between primary position and maximal lateroversion. In latent or manifest latent nystagmus, the nystagmus decreases when the fixating eye is adducted. Patients with manifest congenital nystagmus may use several of these compensation strategies. Because of the difficulties involved in distinguishing between manifest and manifest latent nystagmus without electronystagmography, confusion has arisen regarding the etiologic relationship between congenital nystagmus and infantile esotropia. Such relationship clearly exists in some patients with manifest nystagmus and convergence dampening. However, in most patients with infantile esotropia and congenital nystagmus, the nystagmus is latent or manifest latent and there is no evidence of a causal relationship between these two entities.

Congenital esotropia

Congenital esotropia represents the most common type of strabismus. Its pathogenesis, however, remains uncertain. It is typically characterized as a large angle, constant esotropia with onset during the first six months of life. Associated clinical findings include normal refractive errors for age, amblyopia, dissociated vertical deviation, inferior oblique muscle overaction and nystagmus. It must be distinguished from Duane's retraction syndrome, Moebius syndrome, nystagmus blockage syndrome, and early onset accommodative esotropia, as well as other causes of esotropia in infancy. The surgical management may involve recession of both medial recti muscles, unilateral recession of a medial rectus muscle and a resection of a lateral rectus muscle or three or four muscle surgery.

Binocular micromovement recording of human eyes:--methods

An apparatus is described for binocular recording of micromovements of human eyes, with the contact lens mirror technique used frequently. Horizontal and vertical micromovements of both eyes are recorded simultaneously by means of instruments measuring light-spot positions. Spatial resolution of the measuring instrument is 12 s of arc, while the time resolution is 0.5 ms for this apparatus. The fixation mark (Snellen character) is at a distance of 5 m without any restrictions to the view. The micromovement data are registered by a microcomputer. A second computer enables precise calculation of the results which are given as multicoloured graphs (X/Y-, X/t-graph, velocity/t-graph, frequency analysis, phase correlation of both eyes). In this way the requirements are met for the clinical application of this measuring instrument on patients.

Ocular causes of abnormal head postures

A prospective study was undertaken to analyze the different causes of abnormal head postures on ocular bases. Eight basic mechanisms were found in a series of 188 patients. Incomitance accounted for 62.7% of the head postures and nystagmus for 20.2%. Important diagnostic criteria for evaluating patients with head postures are discussed.