Reika Kono

Prism adaptation response is useful for predicting surgical outcome in selected types of intermittent exotropia

PURPOSE To evaluate the prevalence of prism adaptation response in Japanese patients with intermittent exotropia (X [T]) using the prism adaptation test and to assess whether patients with selected types of X [T] benefit from surgical outcome to which prism adaptation response may contribute. METHODS In a prospective study, 128 consecutive patients with X [T] between 1990 and 1995 were enrolled. The prism adaptation test was conducted by neutralizing the angle of deviation for 2 to 3 hours. Patients who showed an increase in exodeviation by 10triangle up or more with the prism adaptation test were defined as having a prism adaptation response. For classification of the pattern of X [T], we chose a value of 15triangle up as the difference between the distance and near measurements. RESULTS The percentage of patients in whom the prism adaptation response was observed at near fixation was significantly larger than those at distance fixation [35 (27%) patients versus 10 (8%) patients, P <.05]. Of 35 patients shown to have a prism adaptation response at near fixation, 21 patients (83%) had the basic type of exotropia. Fourteen patients (17%) with the basic type were changed to convergence insufficiency type because of an increase in near deviation and were defined as pseudo basic type. Patients with pseudo basic type had a significantly better surgical outcome compared with that of true basic type, whereas in the convergence insufficiency type, no definite tendency was found between the two subtypes, true and pseudo types. CONCLUSION Patients with the pseudo basic type of X [T] in whom a prism adaptation response was demonstrated had a more favorable surgical outcome.

Absence of relationship between oblique muscle size and Bielschowsky head tilt phenomenon in clinically diagnosed superior oblique palsy.

PURPOSE To study whether the variation in maximum oblique muscle size accounts for individual variation in the Bielschowsky head tilt phenomenon (BHTP) in clinically diagnosed superior oblique (SO) palsy. METHODS Seventeen subjects with clinically diagnosed early-onset or idiopathic SO palsy and 14 normal subjects were enrolled in the study. Magnetic resonance imaging (MRI) in coronal and sagittal planes was used for quantitative morphometry of inferior oblique (IO) and SO muscles. Maximum cross-sectional area of the SO and IO cross section at the mid-inferior rectus crossing were determined in central gaze and compared with paretic eye hypertropia on ipsilesional versus contralesional head tilt. RESULTS Mean (+/-SD) maximum SO cross section was 18.1 +/- 3.2 mm(2) in normal subjects, 14.2 +/- 6.8 mm(2) ipsilesional to SO palsy, and 19.2 +/- 4.5 mm(2) contralesional to SO palsy. The ipsilesional SO cross section was significantly smaller than the contralesional (P = 0.004) and normal (P = 0.01) ones. The mean IO cross section was 18.3 +/- 3.5 mm(2) in normal subjects, 21.3 +/- 7.9 mm(2) ipsilesional to SO palsy (P = 0.43), and 22.0 +/- 6.7 mm(2) contralesional to SO palsy (P = 0.26). Hyperdeviation varied with head tilt by 20.1 +/- 5.5 degrees in subjects with SO atrophy, and 10.3 +/- 5.6 degrees in subjects without SO atrophy (P = 0.003). Although oblique muscle cross sections did not correlate with BHTP, subjects with clinically diagnosed SO palsy segregated into groups exhibiting normal versus atrophic SO size. CONCLUSIONS SO size does not account for the variation in BHTP in clinically diagnosed SO palsy, supporting the proposition that the BHTP is nonspecific for SO function.

Displacement of the rectus muscle pulleys simulating superior oblique palsy

PurposeTo investigate the structural basis of three cases of apparent superior oblique (SO) palsy caused by extraocular muscle (EOM) pulley heterotopy.MethodsThree subjects were diagnosed as having decompensated idiopathic left SO palsy on the basis of misalignment in diagnostic gaze positions, response to the head tilt test, and results of the Hess screen test. Magnetic resonance imaging of the orbits in coronal planes was used to determine SO muscle size and contractility and to define the rectus EOM pulley locations. Orbit 1.8 computer simulation was performed for each subject by using measured rectus pulley locations. Simulated binocular alignment was compared with the measurements.ResultsThe maximal SO cross sections of both eyes of each subject were similar, and exhibited similar contractile thickening from supraduction to infraduction. The superior rectus muscle pulleys in three eyes exhibited significant temporal displacement, while the lateral rectus muscle pulleys in five eyes and the medial rectus muscle pulleys in two eyes were displaced significantly inferiorly compared with published norms. Simulations based on observed pulley position abnormalities alone predicted measured Hess screen data better than did simulations incorporating SO weakness, either alone or combined with other structural abnormalities.ConclusionsHeterotopy of the rectus EOM pulleys may be associated with cyclovertical strabismus that simulates SO palsy.

Splitting of the Extraocular Horizontal Rectus Muscle in Congenital Cranial Dysinnervation Disorders

PURPOSE To analyze the horizontal rectus extraocular muscles (EOMs) by orbital magnetic resonance imaging (MRI) in patients with congenital cranial dysinnervation disorders that arises from abnormal development of cranial nerve nuclei or their axonal connections. DESIGN Case series, retrospective analysis. METHODS The morphology of the horizontal rectus EOMs was analyzed in orbital MRI on 4 patients with congenital oculomotor palsy, 26 with congenital superior oblique palsy, and five with Duane syndrome. Orbital imaging was performed by 1.5 tesla (T) and 3T MRI, and quasi-coronal and sagittal images perpendicular and parallel to the long axis of the orbit were obtained at slice thicknesses of 3 and 2 mm. RESULTS The horizontal rectus EOMs were split in 4 of the 35 patients (11%). Splitting was observed in 2 of the five patients (40%) with Duane syndrome, one of the 26 patients (4%) with congenital superior oblique palsy, and 1 of the 4 patients (25%) with oculomotor palsy, but in none of the 6 normal subjects and 12 patients with acquired cranial nerve palsy. CONCLUSION Since splitting of the horizontal rectus EOMs was noted in patients with congenital dysinnervation disorders, including Duane syndrome, Sevels theory that the horizontal rectus EOMs develop from the superior and inferior mesodermal complexes is considered to be reasonable.

Comparative Study of Brain Lesions Detected by Magnetic Resonance Imaging between Strabismus and Nonstrabismus in Infancy

Purpose: To elucidate the causative factors in infantile esotropia, we evaluated morphological abnormalities in brain structures of esotropia patients showing any abnormal neurological signs in comparison to those of normal controls. Methods: Sixty-five developmentally normal children participated in this study. Of these 65, 38 demonstrated infantile esotropia and 27 were normal controls. All underwent magnetic resonance imaging (MRI) of the brain between 2 and 30 months. Results: Abnormal brain findings were noted in 3 (7.9%) children in the strabismus group, whereas none of the children in the normal control group showed brain lesions. In these 3 cases, brain lesions involved periventricular leukomalacia, enlargement of the lateral ventricles with hypoplasia of the corpus callosum and myelination delay at the anterior horn adjacent to the lateral ventricles. Conclusions: Brain lesions that may disturb normal maturation of the visuomotor system and eventually lead to strabismus could be found in some patients without any episode that would cause birth injury.

Large Bielschowsky head-tilt phenomenon and inconspicuous vertical deviation in the diagnostic positions in congenital superior oblique palsy

PURPOSE To report a case of congenital superior oblique palsy with an unusually large Bielschowsky head-tilt phenomenon (BHP) and disproportional inconspicuous vertical deviation. METHODS Case report. RESULTS An 18-year-old woman presented with slight compensatory head tilting and a Bielschowsky head-tilt phenomenon of 50 Delta on left tilting. Magnetic resonance imaging revealed atrophy of the left superior oblique muscle. A Hess screen test showed a slight underaction of the left superior oblique muscle, but neither an obvious overaction of the ipsilateral inferior oblique muscle nor inhibitory palsy of the contralateral superior rectus muscle was found. With a 3-mm recession of the ipsilateral superior rectus muscle, Bielschowsky head-tilt phenomenon decreased to 25 Delta. CONCLUSION A large Bielschowsky head-tilt phenomenon was possibly caused by an increased gain of the otolith-ocular reflex affecting the vertical rectus muscle.

Correction of Cyclovertical Strabismus Induced by Limited Macular Translocation in a Case of Age-Related Macular Degeneration

PURPOSE To report a case of strabismus surgery performed to treat cyclovertical strabismus induced by limited macular translocation. METHODS Case report. RESULTS A 62-year-old man suffering with age-related macular degeneration and subfoveal choroidal neovascularization, RE, underwent limited macular translocation surgery. The fovea was rotated downward, and his visual acuity improved from 20/100 to 20/25 postoperatively. Cyclovertical diplopia persisted for 6 months after the operation. A Hess screen test revealed a pattern that simulated an underaction of the superior oblique muscle and inferior rectus muscle with an overaction of the ipsilateral inferior oblique muscle. To treat the diplopia, advancement of the superior oblique muscle tendon and resection of the ipsilateral inferior rectus muscle were performed. Binocular single vision with 140 seconds of arc for stereopsis was obtained. CONCLUSION Cyclovertical strabismus after limited macular translocation is corrective with conventional surgery on the treated eye.

Vertical Vergence Adaptation in Cases of Superior Oblique Palsy

PURPOSE To investigate the characteristics of vertical adaptation (VA) in superior oblique muscle palsy (SOP). SUBJECTS AND METHODS VA was examined in 15 patients with unilateral congenital SOP, 7 patients with unilateral acquired SOP, and 35 normal volunteers. An adaptive change in the fusion-free ocular alignment, VA, was measured with a computer-aided mirror haploscope. The fusion-free ocular alignment was measured before inserting a 3 prismdiopter vertical prism, immediately after inserting the prism, and at 10 minutes and 30 minutes after insertion. We investigated VA gain, age, vertical fusional range, response of prism adaptation test (PAT), and superior oblique muscle atrophy in magnetic resonance imaging (MRI). RESULTS The VA gain (mean +/- standard deviation, %) at 30 minutes in congenital, acquired, and normal groups was 86 +/- 53, 34 +/- 23 and 58 +/- 16, respectively. The mean of the VA gains at 30 minutes in the congenital group was greatest, and that in the acquired group was least(p < 0.01). In the congenital group there was a correlation between VA gain and response of PAT (p = 0.02, r = 0.60). The VA gain did not significantly correlate with age, vertical fusional range, or muscle atrophy. CONCLUSION The VA gain observed in congenital SOP was greater than that of acquired SOP, and affected the response of PAT.

Effects of vertical muscle surgery on differences in the orientation of Listing's plane in patients with superior oblique palsy

BackgroundAlthough scleral search coils are widely and accurately used for the measurement of Listing’s plane in both eyes, they require specialized equipment and are invasive. In this study, we describe a convenient and less invasive method that uses a synoptometer to analyze the differences in orientation of Listing’s plane (difLP), and the effects of vertical muscle surgery on the difLP tilt in patients with superior oblique palsy (SOP).MethodsSeventeen patients with unilateral congenital SOP (CSOP) and four patients with unilateral acquired SOP (ASOP) who had not undergone any strabismus surgeries were examined. Cyclodeviations of 13 vertical and horizontal gaze points within 30° were measured with a synoptometer, and the difLP tilts in the yaw and pitch planes were analyzed before and after vertical muscle surgery.ResultsThe difLP tilt in the CSOP patients was significantly tilted nasally (p = 0.02) and forward on the lower side (p = 0.001), whereas that in ASOP patients tended to tilt temporally (p = 0.15). Ipsilateral inferior oblique recession (IOR) performed in seven CSOP patients tended to improve the difLP tilt in both the yaw (p = 0.07) and pitch (p = 0.09) planes, whereas contralateral inferior rectus recession (IRR) performed in three CSOP patients significantly improved the difLP tilt in the pitch plane (p = 0.015). The mean excyclodeviations in the 13 gaze points were significantly improved with both procedures (p < 0.0001 for both).ConclusionsThe difLP tilt in the SOP patients could be analyzed with a convenient and less invasive method using a synoptometer, and dissimilar difLP tilts were confirmed in the ASOP and CSOP patients. The results of this study suggest that both IOR and IRR are reasonable treatments for improving the difLP tilt in CSOP patients. IOR should be selected for patients with a steep preoperative difLP tilt to the nasal side, whereas IRR should be selected for patients with a gentle preoperative difLP tilt.

Effects of oblique muscle surgery on the rectus muscle pulley

PurposeTo determine the position of rectus muscle pulleys in Japanese eyes and to evaluate the effect of oblique muscle surgery on rectus muscle pulleys.MethodsQuasi-coronal plane MRI was used to determine area centroids of the 4 rectus muscles. The area centroids of the rectus muscles were transformed to 2-dimensional coordinates to represent pulley positions. The effects of oblique muscle surgery on the rectus muscle pulley positions in the coronal plane were evaluated in 10 subjects with cyclovertical strabismus and, as a control, pulley locations in 7 normal Japanese subjects were calculated.ResultsThe mean positions of the rectus muscle pulleys in the coronal plane did not significantly differ from previous reports on normal populations, including Caucasians. There were significant positional shifts of the individual horizontal and vertical rectus muscle pulleys in 3 (100%) patients with inferior oblique advancement, but not in eyes with inferior oblique recession and superior oblique tendon advancement surgery. The surgical cyclorotatory effect was significantly correlated with the change in the angle of inclination formed by the line connecting the vertical rectus muscles (p = 0.0234), but weakly correlated with that of the horizontal rectus muscles.ConclusionsThe most important factor that affects the pulley position is the amount of ocular torsion, not the difference in surgical procedure induced by oblique muscle surgery.