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Biomedical subjects

Jeong-Min Hwang

Publications and source records attributed to Jeong-Min Hwang.

At least 19 recordsLinked to original sources
PubMed2006

Imaging of the superior rectus in superior rectus overaction after retrobulbar anesthesia.

OBJECTIVE: Vertical diplopia after cataract surgery caused by an overaction of an extraocular muscle is more common when the superior rectus muscle is involved, whereas contracture is more common when the inferior rectus muscle is involved. However, no documented imaging has been presented. The aim of this report was to study the superior rectus in such a patient with magnetic resonance imaging (MRI). DESIGN: Observational case report. METHODS: Ophthalmologic examination and thin-sectioned MRI across the superior rectus muscle were performed in a patient with superior rectus overaction after cataract surgery. MAIN OUTCOME MEASURES: Ocular alignment, ocular movement, and the superior rectus muscle on MRI. RESULTS: Magnetic resonance imaging disclosed focal thickening of the superior rectus muscle near the orbital apex in a patient who showed superior rectus overaction after retrobulbar anesthesia for cataract extraction. CONCLUSIONS: The focal thickening of the superior rectus muscle in this patient is consistent with the theory that segmental contracture leads to overactive muscles after retrobulbar anesthesia.

Anesthesia, Local↗
PubMed2006

Cyclic exotropia associated with retinitis pigmentosa.

PURPOSE: To report the occurrence of cyclic exotropia in a patient with retinitis pigmentosa. METHODS: A 31-year-old man presented with cyclic exotropia of the left eye of 4 years duration that alternated every 24 h. A detailed ophthalmologic examination was performed. RESULTS: The patient showed an orthotropia and a comitant left exotropia of 30 prism diopters at distance and 25 prism diopters at near in the primary position on an exotropic day with a cycle of 48 h. A fundoscopic examination showed bone spicule formation and arteriolar narrowing, and electroretinography showed no response in either eye. A Goldmann visual field examination showed a central island in both eyes. CONCLUSIONS: Cyclic exotropia may occur in patients with retinitis pigmentosa, an association that to the best of our knowledge has not been previously reported in the English ophthalmic literature. Cyclic exotropia is an unusual association with retinitis pigmentosa.

Adult↗
PubMed2006

Objective measurement of visual acuity by optokinetic response determination in patients with ocular diseases.

PURPOSE: To investigate the efficacy of optokinetic nystagmus (OKN) suppression and induction methods for the objective estimation of visual acuities in patients with various ocular diseases. DESIGN: Prospective, descriptive study. METHODS: One hundred seventy-three eyes of 89 patients aged between 27 and 75 years who registered at our institution from January to December 2004 were prospectively enrolled onto this study. Ocular diseases included generalized retinal diseases (47 eyes), media opacity (32 eyes), refractive errors (31 eyes), glaucoma (27 eyes), maculopathies (26 eyes), and optic neuropathies (10 eyes). Horizontal optokinetic stimuli were presented on a 17-inch monitor screen at a distance of 40 cm from the subject in a dark room. Horizontal eye movements were recorded in each eye separately by infrared oculography. Objective visual acuities measured by using OKN suppression or induction methods were compared with subjective visual acuity assessments. The logarithm of minimal angle of resolution visual acuity was 1.03, and ranged from -0.08 to hand movement. RESULTS: Linear regression identified minimum stripe stimuli required to induce OKN by using the OKN induction method, and the minimum dot size required to suppress OKN was found to be correlated with subjective visual acuity (P<.01). The induction method was useful in patients with visual acuities of 20/60 or worse, and the suppression method was useful in patients with visual acuities of 20/200 or better. CONCLUSIONS: Combined use of the OKN induction and suppression methods provides a satisfactory means of determining objective visual acuity.

Adult↗
PubMed2006

Bilateral lateral rectus recession versus unilateral recess-resect procedure for exotropia with a dominant eye.

PURPOSE: To compare the surgical outcomes of bilateral lateral rectus recession and unilateral recess-resect (RR) procedure on the nondominant eye for the patients of exotropia with a dominant fixating eye. DESIGN: Prospective randomized comparative clinical trial. METHODS: One hundred twenty-four patients of exotropia with an invariably fixating eye were enrolled to this study. Patients were assigned randomly to two groups, those who underwent bilateral lateral rectus (BLR) recessions (BLR group) or unilateral RR procedures on the nondominant eye (RR group); surgical outcomes were compared. An outcome was considered satisfactory if there was between 10 prism diopters of exophoria/tropia and 10 prism diopters of esophoria/tropia at 6 months after surgery. RESULTS: In the BLR group, 28 of the 58 patients (48.3%) had a satisfactory outcome, and 30 patients (51.7%) had recurrence. There was no case of overcorrection in the BLR group. In the RR group, 55 of the 66 patients (83.3%) had a satisfactory outcome; 6 patients (9.1%) had recurrence, and 5 patients (7.6%) were overcorrected (P < .001, Fisher's exact test). All overcorrected patients in the RR group had poor stereoacuity and constant exotropia before the operation. The cumulative probability of surgical success was significantly higher in the RR group than in the BLR group (P = .012, log rank test). CONCLUSIONS: In the patients with exotropia with a dominant eye, the unilateral RR procedure resulted in a better outcome than BLR recession surgery. But, the overcorrection rate was significantly higher in the unilateral RR procedure group, especially in those patients with a poor preoperative stereopsis status and constant exotropia.

Adolescent↗
PubMed2006

Injection of cultured autologous fibroblasts into the subconjunctival space of rabbits treated with mitomycin C.

PURPOSE: To investigate whether cultured autologous fibroblasts injected into the subconjunctival space of rabbit may be used as a new treatment modality for conjunctival and subconjunctival atrophy caused by mitomycin C (MMC). DESIGN: Animal study. METHODS: Thirty New Zealand White rabbits were divided into three groups of 10 animals. A situation similar to bleb leakage after trabeculectomy with MMC was created by injecting 0.1 ml of MMC 0.05% weekly for three weeks into the subconjunctival space of 30 eyes of these 30 rabbits. The animals were then divided into control, autologous blood injection, and cultured autologous fibroblast injection groups. Conjunctiva changes were then observed, and eyes were enucleated for histopathologic study at one, two, four, six, and eight weeks after surgery in each of the three groups. RESULTS: In the control group, the conjunctiva was thin and transparent, and subconjunctival fibroblasts were hardly visible, with coarsely arranged collagen fibers. In contrast, the autologous fibroblast injection group showed a thickened and less transparent conjunctiva along with packed fibroblasts and collagen fibers. In the autologous blood injection group, the transparency of the conjunctiva and the density of fibroblast and collagen fiber arrangement lay between those of the control and autologous fibroblast injection groups. CONCLUSIONS: Cultured autologous fibroblast injection may be a feasible and effective treatment modality for conjunctival and subconjunctival atrophy caused by MMC.

Animals↗
PubMed2006

Correlation between topographic profiles of localized retinal nerve fiber layer defects as determined by optical coherence tomography and red-free fundus photography.

PURPOSE: To evaluate the topographic relationship of localized retinal nerve fiber layer (RNFL) defects as determined by optical coherence tomography (OCT) and by red-free fundus photography. METHODS: Sixty-five eyes of 65 patients with localized, wedge-shaped RNFL defects identified in red-free fundus photographs and with matching visual field defects were scanned with the Stratus OCT. On the resulting RNFL thickness report printout, segments of the line graph outside of the 95 and 99% normal limits were defined as "5% OCT defect" and "1% OCT defect," respectively. Correlations between the angular location and angular width of RNFL defects as determined by OCT (OCT defects) and by red-free fundus photography (red-free defects) were evaluated. RESULTS: Angular locations and widths of both 5 and 1% OCT defects were significantly correlated with corresponding red-free defects (all P values<0.001). CONCLUSIONS: There is a strong topographic correlation between characteristics of localized RNFL defects as determined by OCT and red-free photography.

Adult↗
PubMed2006

Efficacy of the lancaster red-green test for the diagnosis of superior oblique palsy.

PURPOSE: The purpose of this study was to evaluate the usefulness of the Lancaster red-green test (LRGT) in patients with superior oblique palsy (SOP). METHODS: The LRGT results of 42 adult patients with unilateral SOP (33 patients) or bilateral SOP (nine patients) were evaluated and compared with those of 21 patients who showed cyclotropia on Lancaster red-green test but did not have SOP (the non-SOP group). The degree of cyclotropia in primary position and downgaze, horizontal and vertical deviation, V pattern, and the presence of alternating hypertropia or reversal of hypertropia in the oblique field of gaze were analyzed using computer imaging software. RESULTS: The SOP groups showed a larger cyclotropia difference between primary position and downgaze than the non-SOP group. The bilateral SOP group showed a significantly larger degree of cyclotropia in the primary position and downgaze and a smaller amount of vertical deviation in the primary position than the unilateral SOP group. Four of nine patients with bilateral SOP and none of 33 patients with unilateral SOP showed an alternating hypertropia and reversal of hypertropia in the oblique field. CONCLUSIONS: The LRGT was found to be useful for the diagnosis of SOP and for the differentiation of unilateral SOP and bilateral SOP.

Adolescent↗
PubMed2006

Polytetrafluoroethylene/polylactide-co-glycolide laminate containing dexamethasone allows delayed adjustable strabismus surgery in a rabbit model.

PURPOSE: To determine the usefulness of polytetrafluoroethylene/polylactide-co-glycolide (PTFE/PLGA) laminate containing dexamethasone in delayed adjustable strabismus surgery. METHODS: A prospective, masked-observer, controlled study was performed in rabbits. Fifty-two rabbit eyes were divided into three groups. After a recession of the superior rectus muscle (SRM), a PTFE/PLGA containing or not containing dexamethasone or balanced saline solution was applied beneath and over the SRM in the three treatment groups: the PTFE/PLGA-dexamethasone group (the P-D group), the PTFE group (the P group), and the control group (group C). Delayed adjustment was performed once on each SRM at 3 or 5 weeks after surgery by a masked observer. Adjustment lengths, the forces required, and degrees of adhesions were evaluated. RESULTS: In the control group, adjustment was possible in no eyes at 3 or 5 weeks after surgery. In group P, adjustment was possible in 6 of 10 eyes at 3 weeks after surgery and in 4 of 9 eyes at 5 weeks after surgery. In group P-D, adjustment was possible in 7 of 9 eyes at 3 and 5 weeks after surgery. CONCLUSIONS: PTFE/PLGA containing dexamethasone was found to allow delayed adjustment in most eyes for up to 5 weeks after surgery without instillation of anti-inflammatory agent.

Animals↗
PubMed2006

Effect of subconjunctivally injected, liposome-bound, low-molecular-weight heparin on the absorption rate of subconjunctival hemorrhage in rabbits.

PURPOSE: To investigate the effect of subconjunctival injection of liposome-bound, low-molecular-weight heparin (LMWH) on the absorption rate of subconjunctival hemorrhages. METHODS: Subconjunctival hemorrhages were induced in both eyes of 30 rabbits by the subconjunctival injection of 0.1 mL of autologous blood from auricular marginal veins. After 8 hours, randomized subconjunctival injections of one of three materials were made: 5 IU/mL liposome-bound LMWH (0.1 mL) in 18 eyes (group A), only liposomes (0.1 mL) in 14 eyes (group B), the free form of LMWH (5 IU/mL, 0.1 mL) in 14 eyes (group C), or no injection in 14 eyes (group D). Subconjunctival hemorrhages were photographed with a digital camera at 8, 24, 48, 72, 96, and 120 hours after induction of subconjunctival hemorrhages, sized with an image analyzer, and compared between groups. RESULTS: Subconjunctival hemorrhages were absorbed faster in group A (liposome-bound LMWH injected) than in with group B (liposome injected). Comparison of groups A and C (free LMWH injected) showed statistical differences in the absorption rates at 96 and 120 hours except at 24, 48, and 72 hours. The mean elapsed time for the complete resorption of subconjunctival hemorrhages was shortest in group A among four groups, whereas group B and the control showed no significant differences. The ocular and systemic absorption of LMWH were significantly lower after injection of the liposome-bound than the free form. CONCLUSIONS: The subconjunctival injection of liposome-bound LMWH appears to enhance subconjunctival hemorrhage absorption in rabbits.

Absorption↗
PubMed2005

Visual prognosis of amblyopia associated with myelinated retinal nerve fibers.

PURPOSE: To investigate the visual prognosis of amblyopia associated with anisomyopia and myelinated nerve fibers. DESIGN: Retrospective noncomparative case series. METHODS: Twelve children with amblyopia associated with anisomyopia and myelinated nerve fibers were treated with spectacle correction after cycloplegic refraction and occlusion therapy for amblyopia. Their visual acuity was measured at each visit to the clinic. The patients were divided into three groups according to their final visual acuity, and statistical analyses were performed to evaluate the differences among these groups in terms of the initial age, spherical equivalent, anisometropia, the area of myelination, final age, and follow-up period. RESULTS: The mean refractive error of the 12 children in spherical equivalents was -8.16 diopters (range -1.50 to approximately -13.00 diopters). The mean age at the initiation of therapy was 4.2 years (range 2.1 to 8.6) and the mean follow-up period was 2.6 years (range 0.5 to 5.1). After the occlusion treatment, visual acuity improved to 20/30 in four patients, and to 20/60 in one patient. In the remaining six patients, visual acuity remained at 20/200 or worse. The amount of anisometropia and the area of myelination were significantly different between the group with a final visual acuity of 20/40 or better and the group with a final visual acuity of worse than 20/200. CONCLUSION: The visual acuity of about one third of the amblyopes with myelinated nerve fibers improved to 20/30. The prognostic factors for the visual improvement were the amount of anisometropia and the area of myelination.

Amblyopia↗
PubMed2005

The use of Surgi Wrap in delayed adjustable strabismus surgery.

PURPOSE: To determine the effect of Surgi Wrap (MacroPore Biosurgery, Inc, San Diego, California, USA) in delayed adjustable strabismus surgery. DESIGN: An animal study. METHODS: A prospective, masked-observer, controlled study was performed in rabbits. Forty-eight eyes of 24 rabbits were divided into two groups. After recession of the superior rectus muscle (SRM), Surgi Wrap was applied beneath and over the SRM in the Surgi Wrap group, and no barrier was applied in the control group. Delayed adjustment was performed once on each superior rectus muscle at 1, 2, and 3 weeks after surgery by a masked observer. The possible length to adjust, the force required for the adjustment, and the degree of any adhesions were also evaluated. RESULTS: In the control group, adjustment was impossible in all of the five eyes at 1, 2, and 3 postoperative weeks, respectively. In the Surgi Wrap group, adjustment was possible in four of 10 eyes at 1 week after surgery, in two of 10 eyes at 2 weeks after surgery, and in none of the 10 eyes at 3 weeks after surgery. CONCLUSION: The use of Surgi Wrap could delay adjustment in some of the eyes up to 1 or 2 weeks after surgery. Surgi Wrap could be helpful for short-term delayed adjustment in rabbit eyes.

Animals↗
PubMed2005

Presence of the abducens nerve according to the type of Duane's retraction syndrome.

OBJECTIVE: To analyze whether the presence of the abducens nerve might depend upon the type of Duane's retraction syndrome (DRS). DESIGN: Observational case series. PARTICIPANTS: Sixteen patients with type 1 DRS, 2 patients with type 2 DRS, and 5 patients with type 3 DRS. METHODS: Ophthalmologic examination and thin-sectioned magnetic resonance imaging (MRI) at the brain stem level were performed in 23 DRS patients. To confirm the accuracy of the procedure, we compared the results obtained with those of a control group of 30 individuals using the same technique. MAIN OUTCOME MEASURES: Examination of ductions and versions and the presence of the abducens nerve on MRI. RESULTS: The abducens nerve on the affected side could not be observed using MRI in 18 (100%) of 18 eyes (16 patients) with type 1 DRS and in 3 of 5 eyes with type 3 DRS. Conversely, the abducens nerve was observed in 2 of 2 eyes with type 2 DRS and 2 of 5 eyes with type 3 DRS. The abducens nerve was observed in 60 (100%) of 60 eyes screened as controls. CONCLUSIONS: The abducens nerve on the affected side was absent in type 1 DRS patients and some type 3 DRS patients, but present in type 2 DRS patients as well as in some type 3 DRS patients. In terms of the presence or absence of the abducens nerve, type 1 and type 2 DRS were homogenous, and type 3 DRS was heterogenous.

Abducens Nerve↗
PubMed2005

Hypoplastic oculomotor nerve and absent abducens nerve in congenital fibrosis syndrome and synergistic divergence with magnetic resonance imaging.

OBJECTIVE: There is only one neuropathologic report of congenital fibrosis of the extraocular muscles (CFEOM), and none of synergistic divergence. The aim of this report was to study the oculomotor nerve and the abducens nerve in 2 such patients with magnetic resonance imaging. DESIGN: Observational case reports. METHODS: Ophthalmologic examination and thin-sectioned magnetic resonance imaging across the brainstem level were performed in 2 patients with CFEOM and synergistic divergence. To confirm the accuracy of the procedure, we compared the results obtained with those of a control group of 40 individuals using the same technique. MAIN OUTCOME MEASURES: The oculomotor nerve and the abducens nerve on magnetic resonance imaging. RESULTS: Magnetic resonance imaging disclosed bilateral hypoplasia of the oculomotor nerve in both patients, and absence of the abducens nerve on the affected side of synergistic divergence. The oculomotor and abducens nerves were observed in 80 of 80 eyes (100%) screened as controls. CONCLUSIONS: In both patients with CFEOM and synergistic divergence, the oculomotor nerve was hypoplastic bilaterally, and the abducens nerve was absent on the side exhibiting synergistic divergence.

Abducens Nerve↗
PubMed2005

Development of pupillography using image processing.

PURPOSE: Pupillary examination is an important objective method to diagnose lesions of the anterior visual pathways. However, errors and faults may easily alter the interpretation and value of the test as it is highly dependent on the examiner's skills. Therefore, we tried to develop a pupillography which is independent of the examiner. METHODS: Hardware composed of a binocularly measuring instrument adapted for an infrared charge coupled device (CCD) was developed. Two arrays of infrared light emitting diodes (LED) were supplied in front of each of the subject's eyes. A microcontroller to modulate these LED was developed, as was software to save and analyze the pupil images. The hardware was able to deliver a light to either eye or to both eyes, and to change the time, frequency, and intensity of the stimulus. The software automatically analyzed the pupil size and location by image processing. Pupil size was calculated continuously. After artifact elimination, the response amplitudes of the pupils were determined for the right and left pupils. RESULTS: Pupillary images of size 320 x 240, at 30 frames/second, were saved and processed to evaluate the change of the actual pupil size and the velocity of pupillary response. CONCLUSIONS: A pupillography to measure, save and analyze the pupillary response using image processing was developed. Further detailed clinical studies with a large number of patients will be required to validate this new method.

Diagnostic Techniques, Ophthalmological↗