Biomedical subjects

Sei Yeul Oh

Publications and source records attributed to Sei Yeul Oh.

8 recordsLinked to original sources

PubMed2003

Accessory lateral rectus muscle in a patient with congenital third-nerve palsy.

PURPOSE: To report a case of accessory lateral rectus muscle in a patient with congenital third-nerve palsy. DESIGN: Observational case report. METHODS: An 18-year-old boy with left exodeviation, ptosis, pupil dilation, and limited adduction, supraduction, and infraduction of his left eye. Left lateral rectus muscle recession and medial rectus muscle resection were done. An orbital computed tomographic (CT) scan was obtained. RESULT: Intraoperatively, an accessory muscle was found under the lateral rectus muscle. Postoperatively, the orbital CT scan showed accessory lateral rectus muscle located in the medial side of the lateral rectus muscle. CONCLUSION: Accessory lateral rectus muscle was demonstrated in a patient with congenital third-nerve palsy using lateral rectus muscle surgery and an orbital CT scan.

Adolescent↗

PubMed2003

Evidence for a pulley of the inferior oblique muscle.

PURPOSE: This study was undertaken to investigate evidence for a connective tissue pulley constraining the path of the inferior oblique (IO) muscle. METHODS: From magnetic resonance images, the cross-sectional area, path, and orbital relationships of the human IO were determined in multiple gaze positions. Rectus pulleys were directly imaged with intravenous gadodiamide contrast. Images were compared with serial histologic sections of IO muscles of humans and monkeys. RESULTS: The IO path from origin to the lateral border of the inferior rectus (IR) muscle was straight. Lateral to the IR, the IO curved to follow the globe. At the point of IR crossing, the IO moved anteriorly from infraduction to supraduction by approximately 53% of the IR insertion's travel. Gaze-related change in IO cross section was demonstrable near the IR center. The gaze-related inflection in IO path corresponded to its encirclement by a pulley consisting of a dense ring of collagen, stiffened by elastin and smooth muscle, and united with the IR pulley. Orbital layer fibers of the IO inserted on its pulley, the lateral rectus (LR) pulley, and associated connective tissues. CONCLUSIONS: Like the rectus muscles, the human and monkey IO has a connective tissue pulley serving as its functional origin. The position of the IO pulley is influenced by its coupling to the actively moving IR pulley, whereas in turn the IO orbital layer inserts on and presumably shifts the IR and LR pulleys. These intercouplings facilitate implementation by rectus extraocular muscle suspensions of a commutative ocular motor plant.

Adult↗

PubMed2002

Chemoreduction followed by local therapy and adjuvant chemotherapy for advanced intraocular retinoblastoma: a pilot study in a single center.

Intraocular (IO) retinoblastoma (RB) has traditionally been treated with enucleation (ENU) or external beam radiotherapy (EBRT). Recently, clinical trials are in progress to cure RB without ENU or EBRT in order to salvage the globe and to avoid unacceptable side effects of EBRT. We performed a pilot study to treat patients with advanced Reese-Ellsworth (RE) stage IO RB with initial chemotherapy (CRx) followed by local therapy (LT) and adjuvant CRx. Ten eyes (8 RE group V, 2 RE group IV) from 9 patients were enrolled from March 2001 to November 2001. All tumors responded to CRx. In 5 of 10 eyes, the RB was enough to be treated with LT after chemoreduction. One patient who underwent LT is waiting for ENU due to post-cryotherapy complication. For a median follow-up of 13 months (8-16 mo), 4 eyes that received LT and adjuvant CRx were relapse-free. A patient with bilateral RB who failed to be a candidate for LT was rescued with high-dose CRx and hematopoietic stem cell transplantation. Consequently, by treating patients according to our strategy, we were able to salvage 6 out of 10 eyes without ENU or EBRT. These results suggest that chemoreduction followed by LT and adjuvant CRx might offer the opportunity to salvage the globe and vision even in patients with advanced stage IO RB.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed2002

Incomitant strabismus associated with instability of rectus pulleys.

PURPOSE: Connective tissue pulleys serve as functional mechanical origins of the extraocular muscles (EOMs) and are normally stable relative to the orbit during gaze shifts. This study evaluated pulley stability in incomitant strabismus. METHODS: Contiguous 2- or 3-mm thick magnetic resonance images (MRIs) perpendicular to the orbital axis spanned the anteroposterior extents of 12 orbits of six patients with incomitant strabismus. Imaging was performed in central gaze, supraduction, infraduction, abduction, and adduction. Rectus EOM paths were defined by their area centroids and plotted in a normalized, oculocentric coordinate system. Paths of EOMs ran toward the pulleys. Sharp EOM path inflections in secondary gaze indicated pulley locations in three dimensions. RESULTS: MRI revealed substantial inferior shift of the lateral rectus (LR) pulley of up to 1 mm during vertical gaze shifts in patients with axial high myopia and a posterior shift from abduction to adduction in simulated Brown syndrome. There was substantial LR pulley shift opposite the direction of vertical gaze in a subject with X-pattern exotropia who had undergone repeated LR surgery. The medial rectus (MR) pulley shifted inferiorly with gaze elevation in Marfan syndrome. Pulley instability was associated with significantly increased globe translation during gaze shifts. CONCLUSIONS: Pulley instability, resulting in EOM sideslip during ductions, occurs in some cases of incomitant strabismus. Resultant patterns of strabismus may depend on static pulley positions, pulley instability, and coexisting globe translation that alters pulley locations relative to the globe. Translational instability of pulleys and the globe could produce abnormalities in actions of otherwise normal EOMs, and connective tissue disorders causing these instabilities should be considered as potential causes of strabismus.

Adult↗

PubMedDate not supplied

Clinical feature analysis of congenital optic nerve abnormalities.

PURPOSE: We investigated the clinical characteristics and associated ocular and systemic anomalies in young children with congenital optic nerve abnormalities, and evaluated the therapeutic results of treatment for strabismus and amblyopia. METHODS: A retrospective study was conducted using the medical records of patients who were diagnosed with congenital optic nerve abnormalities in our hospital between 1995 and 2004. RESULTS: This study involved 72 eyes of 51 young children (M : F = 25 : 26); 21 of these patients (41.2%) had bilateral abnormalities. The types and percentages of each abnormality were as follows: optic nerve hypoplasia, 47%; optic disc coloboma, 31.4%; morning glory syndrome, 11.8%; and myelinated nerve fiber, 9.8%. The first clinical manifestations noticed by parents were strabismus and decreased visual acuity. Occlusion therapy was carried out in 16 patients, and the visual acuities of two patients were improved by more than two lines of the Early Treatment Diabetic Retinopathy Study visual acuity chart. Accompanying strabismus was found in 70.6% of the patients; 14 patients underwent strabismic surgery, and 10 of these patients (41.2%) maintained a stable angle. CONCLUSIONS: The most common congenital optic nerve abnormality was optic nerve hypoplasia, and the associated systemic abnormalities found were optic nerve hypoplasia and disc coloboma. Patients with congenital optic nerve abnormalities usually have a generally poor visual prognosis, but we emphasize the importance of treatment for associated strabismus and amblyopia.

Child, Preschool↗

PubMedDate not supplied

Acute effect of bupivacaine and ricin mAb 35 on extraocular muscle in the rabbit.

PURPOSE: To identify acute histologic change of extraocular muscles induced by bupivacaine or ricin mAb 35 injection. METHODS: The superior rectus and inferior rectus of white rabbits were injected with bupivacaine (0.4 mg in 0.3 ml) or ricin mAb 35 (0.2 microg/kg in 0.3 ml). After 1, 2, and 4 weeks, the rectus muscles were harvested, and postinjection changes in the muscle layers were examined histopathologically. RESULTS: Bupivacaine and ricin mAb 35 induced myotoxic changes in both the orbital and the global layers. However, the inflammation and the myofiber destruction produced by bupivacaine injection was localized to the injection site, which compared with the diffuse change induced by ricin mAb 35. Inflammation reduced rapidly over 2 weeks. Regenerating myofibers with a central nucleus were found at 1 week after injecting these myotoxins. Four weeks after injection, the acute changes induced by these two toxins respectively were much recovered with prominent myofiber regeneration. CONCLUSIONS: We found that extraocular muscle has a superb ability to recover from the acute injury induced by bupivacaine or ricin mAb 35, and the two myotoxins induce unique damage including the predilection of muscle layers and duration of damage persisted. Further investigation about the functional change during recovery from the myotoxin-induced injury of extraocular muscles is needed.

Anesthetics, Local↗

PubMedDate not supplied

The factors influencing visual development in blepharophimosis-ptosis-epicanthus inversus syndrome.

PURPOSE: To investigate the factors influencing visual development in blepharophimosis-ptosis-epicanthus inversus syndrome. MATERIALS AND METHODS: The study population comprised 20 patients with blepharophimosis-ptosis-epicanthus inversus syndrome who were referred for an oculoplastic opinion. The ocular examination included measurement of Snellen visual acuity, cycloplegic refraction, ocular movements and alignment, and the presence of amblyopia. Patients were treated with spectacle correction, occlusion therapy, strabismus surgery, and oculoplastic surgery if necessary. Minimum follow-up was 2 years. RESULTS: Nine (45%) patients had amblyopia; 5 (25%) of these patients had unilateral amblyopia and 4 (20%) had bilateral amblyopia. Six (67%) patients with amblyopia had a significant coexisting strabismus. A significant strabismus was present in 11 (55%) patients; 6 (55%) of these patients had unilateral or bilateral amblyopia. Patients with strabismus were more likely to have amblyopia than those without. A total of 14 (70%) patients had refractive error; 6 (43%) of these patients had amblyopia. CONCLUSIONS: Patients with blepharophimosis-ptosis-epicanthus inversus syndrome had a high rate of amblyopia, especially bilateral amblyopia. Patients with strabismus were more likely to have amblyopia than those without. Patients also had a high incidence of refractive errors.

Adult↗

PubMedDate not supplied

Extraocular muscle imaging in complex strabismus.

BACKGROUND AND OBJECTIVE: Abnormalities of extraocular muscle are an unusual cause of complex strabismus. The traditional evaluation based on clinical examinations is insufficient for the interpretation of incomitant motility disorders resulting from extraocular muscle anomalies. Extraocular muscle imaging by computed x-ray tomography (CT) or magnetic resonance imaging (MRI) can provide useful information for diagnosis, pathophysiology, and treatment of complex strabismus. PATIENTS AND METHODS: Five cases of complex strabismus resulting from congenital anomalies of the extraocular muscles and their successful evaluation using extraocular muscle imaging are described. RESULTS: Orbital CT or MRI scan was obtained in five patients who had unusual incomitant strabismus. It confirmed the diagnosis of the absence of the medial rectus muscle, accessory lateral rectus muscle, atrophy of the inferior or both superior and medial rectus muscles, and abnormal thickening of the levator palpebrae superioris and superior rectus muscle. CONCLUSIONS: Extraocular muscle imaging is a useful technique for evaluating anatomic abnormalities. It should be considered when evaluating patients with atypical strabismus.

Adolescent↗