Assessing amblyopia treatment using multifocal visual evoked potentials.

BACKGROUND: To evaluate the effect of occlusion treatment for anisometropic amblyopia using multifocal visual evoked potentials (mfVEPs). METHODS: The patients for this study comprised 19 patients (mean age 6.05 ± 1.65 years) with anisometropic amblyopia underwent mfVEP analysis using the RETIscan® system before and after occlusion treatment. After dividing the area into six ring areas and four quadrants, we analyzed the amplitudes and latencies of the mfVEPs. RESULTS: The amplitudes of ring 1 (central field) in amblyopic eyes after treatment were significantly higher than those in the other rings (p = 0.001). The mfVEP amplitudes in each of the six rings between amblyopic eyes and fellow eyes at diagnosis and after occlusion treatment showed no significant differences. In quadrant 1 the amplitudes of the amblyopic eyes and fellow eyes were significantly different at the time of diagnosis (p = 0.005), whereas after occlusion treatment there was no significant difference (p = 0.888). The amplitudes for each of the six rings at diagnosis and after occlusion treatment in amblyopic eyes versus fellow eyes showed no significant difference. There were also no differences in the amplitudes in each of the four quadrants at the time of diagnosis and after occlusion treatment in amblyopic eyes versus fellow eyes. No significant difference was found in the comparison of latency values in each of the six rings or in each of the four quadrants at diagnosis and after occlusion treatment in amblyopic eyes versus their fellow eyes. CONCLUSIONS: The amplitudes of quadrant 1 in amblyopic eyes compared with those of the fellow eyes at diagnosis were increased after occlusion treatment. Changes of the difference between amblyopic eyes and fellow eyes in quadrant 1 after occlusion treatment could be a useful, objective method for monitoring improvement in visual acuity.

Extratarsal presentation of chalazion.

PURPOSE: We report a case of atypical, extratarsal chalazion referred with a history of a chronic inflammatory mass found on the edge of the lower eyelid. METHODS: A 3-year-old female developed a small mass on the medial side of the right lower lid in 4-month duration. She was seen by her ophthalmologist and the diagnosis of a chalazion was made. Over the ensuing one month with warm compression, the lesion subsided and the new lesion appeared away from the edge on the lateral eyelid 3 months ago. RESULTS: She underwent surgery and drainage was performed. We found a track, a proof of migration, on the lower tarsal conjunctiva in the medial side of the right eyelid during surgery. CONCLUSIONS: Long-term observation in chalazion may induce migration with tract and express as an atypical chalazion.

The orbital volume measurement in patients with ventriculoperitoneal shunt.

Enophthalmos occurs from the increased bony volume or decreased soft tissue volume in the orbit and can be caused in patients with long-term ventriculoperitoneal (VP) shunt. This study tried to find out the change of orbital volume by measuring the orbital volume before and after operation in adult patients who underwent VP shunt for hydrocephalus. The 2 evaluators measured orbital volume by using ITK-SNAP 2.4 program with double-blind test for computed tomography images before and after operation targeting 36 patients over the age of 18 who underwent VP shunt with pressure-controlled valve from 2003 to 2011. Wilcoxon matched-pairs signed-rank test of GraphPad software was used to statistically analyze the difference in orbital volume change before and after operation. In case of mean pre-op orbital volume of total 36 patients, the right was measured as 23.72 ± 4.65 cm(3), the left as 23.47 ± 4.61 cm(3), the post-op right as 24.67 ± 4.70 cm(3), and the left as 24.18 ± 4.63 cm(3), showing no statistically significant difference (P = 0.106). The mean pre-op orbital volume of 14 people (28 eyes) followed for more than 11 months was 25.06 ± 4.58 cm(3) in the right and 24.4 ± 5.02 cm(3) in the left and the mean post-op orbital volume was 27.0 ± 4.28 cm(3) in the right and 25.76 ± 3.92 cm(3) in the left, showing statistically significant differences in the change of the volume before and after shunt operation (P = 0.0057). In patients who maintain long-term shunt devices after VP shunt, remodeling of matured orbital bone may be caused due to the change in pressure gradient between cranial cavity and orbit and the possible occurrence of resulting secondary enophthalmos by increased orbital volume should be considered.

Enlargement of the sella turcica in pseudotumor cerebri.

OBJECT: The sella turcica usually appears partially empty in MR images obtained from patients with chronic elevation of intracranial pressure. The authors measured the size of the sella turcica to determine if enlargement of the pituitary fossa explains the partially empty sella associated with pseudotumor cerebri. METHODS: The medical records from 2005 to 2011 of a single neuro-ophthalmologist were searched to identify consecutive patients with pseudotumor cerebri. Age-matched control patients were selected from the same practice. The sella turcica and pituitary gland were measured on sagittal T1-weighted MR images. RESULTS: Measurements were obtained for 48 patients with pseudotumor cerebri and 48 controls. The cross-sectional area of the sella was 38% greater in the patients with pseudotumor cerebri, with only a slight reduction in mean pituitary gland size. CONCLUSIONS: Chronic elevation of intracranial pressure is associated with bony enlargement of the sella turcica. Enlargement of the sella turcica contributes to its partially empty appearance.

Bupivacaine injection to lateral rectus in abducens nerve palsy.

A 49-year-old female presented with bilateral abducens nerve palsies. She had 75 prism diopter esotropia. The extraocular movement of the lateral rectus was -1 limitation for the right eye and -4 limitations for the left. After performing orbital magnetic resonance imaging (MRI), 2 mL of bupivacain (5 mg/mL) was injected into the left lateral rectus (LR). One month after injection, a further orbital MRI was performed. Subsequently, recession of both medial rectus (6 mm) and resection of the left LR (9 mm) were performed. After one month, bupivacaine had no hypertrophic effects. There was little change in angle of deviation. The orbital MRI scan showed a 1.91% increase in volume compared to the muscle prior to the injection. Histological findings showed no muscle fibers of the left LR muscle, only the fiber nucleus and the collagen that replaced the fibers. We report on the changes in stiffness and muscle volume and on the histology of the muscle one month after injecting bupivacaine into the paralyzed left LR muscle combined with standard surgical treatment.

Oculomotor neuromyotonia with lid ptosis on abduction.

Ocular neuromyotonia is an episodic involuntary contraction of one or more of the extraocular muscles resulting from spontaneous neural discharges of the oculomotor nerve. It is characterized by symptomatic diplopia for the duration of the contraction and occurs either spontaneously or after a sustained eccentric gaze. Although the mechanism of ocular neuromyotonia is not fully understood, primary or secondary aberrant regeneration and consequent ephaptic transmission generally are held to be involved. We report the case of a patient with right oculomotor neuromyotonia accompanied by lid ptosis on abduction of the left eye who was successfully treated with oral carbamazepine.

Assessment of visual disability using visual evoked potentials.

BACKGROUND: The purpose of this study is to validate the use of visual evoked potential (VEP) to objectively quantify visual acuity in normal and amblyopic patients, and determine if it is possible to predict visual acuity in disability assessment to register visual pathway lesions. METHODS: A retrospective chart review was conducted of patients diagnosed with normal vision, unilateral amblyopia, optic neuritis, and visual disability who visited the university medical center for registration from March 2007 to October 2009. The study included 20 normal subjects (20 right eyes: 10 females, 10 males, ages 9-42 years), 18 unilateral amblyopic patients (18 amblyopic eyes, ages 19-36 years), 19 optic neuritis patients (19 eyes: ages 9-71 years), and 10 patients with visual disability having visual pathway lesions. Amplitude and latencies were analyzed and correlations with visual acuity (logMAR) were derived from 20 normal and 18 amblyopic subjects. Correlation of VEP amplitude and visual acuity (logMAR) of 19 optic neuritis patients confirmed relationships between visual acuity and amplitude. We calculated the objective visual acuity (logMAR) of 16 eyes from 10 patients to diagnose the presence or absence of visual disability using relations derived from 20 normal and 18 amblyopic eyes. RESULTS: Linear regression analyses between amplitude of pattern visual evoked potentials and visual acuity (logMAR) of 38 eyes from normal (right eyes) and amblyopic (amblyopic eyes) subjects were significant [y = -0.072x + 1.22, x: VEP amplitude, y: visual acuity (logMAR)]. There were no significant differences between visual acuity prediction values, which substituted amplitude values of 19 eyes with optic neuritis into function. We calculated the objective visual acuity of 16 eyes of 10 patients to diagnose the presence or absence of visual disability using relations of y = -0.072x + 1.22 (-0.072). This resulted in a prediction reference of visual acuity associated with malingering vs. real disability in a range >5.77 µV. The results could be useful, especially in cases of no obvious pale disc with trauma. CONCLUSIONS: Visual acuity quantification using absolute value of amplitude in pattern visual evoked potentials was useful in confirming subjective visual acuity for cutoff values >5.77 µV in disability evaluation to discriminate the malingering from real disability.

Foveal retinoschisis misdiagnosed as bilateral amblyopia.

Juvenile foveal retinoschisis is one of the most common causes of bilateral macular degeneration in young boys. School age with accommodative esotropia may develop amblyopia due to late correction of hyperopia. Retinoschisis is hard to diagnose in patient with subtle macula change and hyperopic amblyopia. We report a case of bilateral foveal retinoschisis before and after treatment with topical dorzolamide, which was misdiagnosed as bilateral hyperopic amblyopia. Optical coherence tomography should be considered in diagnostic procedures of children with hyperopic amblyopia.

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.

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.