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ABSTRACT: This study sought to characterize the optic disc morphology, particularly the cup-to-disc ratio of the optic nerve head in children with idiopathic intracranial hypertension. The medical charts and digital optic disc photos of children with confirmed diagnosis of idiopathic intracranial hypertension were reviewed retrospectively. The optic disc area, cup area, and cup-to-disc ratio were measured digitally using VISUPAC software, and the mean values of those parameters were compared to the published norms. Of children with idiopathic intracranial hypertension, 83% had absence of the physiological cup of the optic disc, compared to 10% of children in the general population of the same age. The median disc area was 2.2 mm(2), and median cup area was 0.0mm(2), compared to the published norms of 2.69 mm(2) and 0.44 mm(2), respectively. There is very significantly high prevalence of small optic disc cups in children with idiopathic intracranial hypertension, with the cup being absent on majority of cases in our patient cohort. This may signal an underlying systemic predisposition to the development of intracranial hypertension.
Journal of child neurology 10/2012; · 1.59 Impact Factor
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ABSTRACT: Juvenile nasopharyngeal angiofibroma is a well-described but rare benign tumor that mainly affects adolescent boys. Although it is capable of extravagant local extension and tissue destruction, the tumor is amenable to effective therapy. Ocular or visual complications have been little noted in the literature. We report a case whose sole symptom was unilateral transient visual impairment and findings were limited to a nonspecific optic disk edema.
Journal of AAPOS: the official publication of the American Association for Pediatric Ophthalmology and Strabismus / American Association for Pediatric Ophthalmology and Strabismus 02/2010; 14(1):90-2. · 1.07 Impact Factor
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ABSTRACT: Johanson-Blizzard syndrome is a rare autosomal-recessive congenital disorder characterized by hypoplastic nasal alae, midline scalp defects, deafness, microcephaly, hypothyroidism, absent permanent teeth, malabsorption, and failure to thrive. The literature was reviewed to define the reported spectrum of ocular manifestations, which are not well documented. We found that nasolacrimal system malformations are a common feature of Johanson-Blizzard, whereas intraocular malformations are rare. This report describes the ophthalmologic findings and management of 2 affected children.
Journal of AAPOS: the official publication of the American Association for Pediatric Ophthalmology and Strabismus / American Association for Pediatric Ophthalmology and Strabismus 09/2009; 13(5):512-4. · 1.07 Impact Factor
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ABSTRACT: To determine whether visual functions are decreased in children with infantile spasms and vigabatrin-attributed retinal toxicity.
Contrast sensitivity and grating acuity were measured by using sweep visual evoked potential (VEP) testing in 42 children with infantile spasms (mean age, 29.23 +/- 18.31 months). All children had been exposed to vigabatrin (VGB) for a minimum of 1 month. These children were divided into retinal toxicity and no toxicity groupings based on 30-Hz flicker amplitude reductions on the full-field electroretinogram. A multivariate analysis of variance (MANOVA) compared visual functions between children with and without retinal toxicity.
The MANOVA showed that visual function was significantly affected by VGB retinal toxicity. Further univariate analysis revealed that grating acuity was significantly reduced in children with toxicity. No differences in contrast sensitivity were found between children with toxicity and those without.
Reduced visual functions from VGB-attributed retinal toxicity can be detected in children with infantile spasms with the sweep VEP.
Investigative ophthalmology & visual science 04/2009; 50(8):4011-6. · 3.43 Impact Factor
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ABSTRACT: To investigate whether ocular torsion and vertical misalignment differ in the upright vs supine position in skew deviation and to compare these findings with those in trochlear nerve palsy.
Ten patients with skew deviation, 14 patients with unilateral peripheral trochlear nerve palsy, and 12 healthy subjects were prospectively recruited. With subjects first in the upright position and then in the supine position, ocular torsion was measured by double Maddox rods and vertical misalignment was measured by the prism and alternate cover test.
In patients with skew deviation, the abnormal torsion and vertical misalignment in the upright position decreased substantially with change to the supine position, whereas in patients with trochlear nerve palsy, it changed little between positions. Torsion was decreased by 83% in patients with skew deviation, 2% in patients with trochlear nerve palsy, and 6% in healthy subjects (P < .001). Similarly, vertical misalignment was decreased by 74% in patients with skew deviation and increased by 5% in patients with trochlear nerve palsy and 6% in healthy subjects (P < .001).
Our findings provide the basis for additional clinical tests to support the classic 3-step test: ocular torsion and vertical misalignment that decrease from the upright position to the supine position indicate skew deviation, whereas torsion and vertical misalignment that do not change significantly between positions indicate trochlear nerve palsy.
Archives of ophthalmology 07/2008; 126(7):899-905. · 3.86 Impact Factor
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ABSTRACT: To evaluate the accuracy of ultrasound biomicroscopy (UBM) in measuring the distance (in mm) from limbus to the insertion of vertical rectus muscles (superior rectus and inferior rectus compared with the "gold standard" surgical caliper at the time of surgery.
Prospective, masked, observational study of 31 vertical rectus muscle insertions in which we compared the measurements from the limbus as measured by 50 MHz UBM, either preoperatively or at the time of anesthesia, with that measured by surgical caliper intraoperatively. Measurements (UBM and surgical) were evaluated by two different observers and analyzed using the Bland-Altman method. All UBM measurements were done by the same author. The intraclass correlation coefficient (ICC) and Pearson coefficient with 95% confidence intervals were used to quantify the degree of agreement between the two methods.
Thirty-one vertical muscles were evaluated (13 superior rectus and 18 inferior rectus, of which 7 muscles were reoperations). The average for UBM measurements was 6.63 mm and for surgical caliper was 7.09 mm. The measurements for the two methods were all within +/-2 standard deviations of the mean. Only three measurements showed differences more than 1 mm. The ICC was 0.78 and Pearson coefficient was 0.85, indicating a "very good" correlation between the two methods. The longest distance from the limbus that could be accurately measured with the UBM was 12 mm. In one case a pseudotendon was differentiated from the true insertion of a previously recessed superior rectus muscle.
The UBM and surgical measurements showed "very good" correlation when allowing for a margin of error of +/-1.0 mm between the two modalities, indicating that the UBM is a good predictor of the position of the vertical rectus muscles.
Journal of AAPOS: the official publication of the American Association for Pediatric Ophthalmology and Strabismus / American Association for Pediatric Ophthalmology and Strabismus 05/2008; 12(2):128-31. · 1.07 Impact Factor
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ABSTRACT: To determine whether the age of strabismus onset and the degree of stereopsis are related to the development of dissociated vertical deviation (DVD) in patients with intermittent exotropia and to describe the characteristics of DVD in patients with intermittent exotropia and DVD.
Retrospective record review of patients with (1) intermittent exotropia with DVD; (2) infantile esotropia with DVD; and (3) intermittent exotropia without DVD. Age of strabismus onset, stereopsis, strabismus measurements, and the response of DVD to the Bielschowsky head-tilt test were compared among the three groups.
Fifty-two children with intermittent exotropia and DVD were identified. In patients with intermittent exotropia with DVD and intermittent exotropia without DVD group, the mean age of strabismus onset was 12.7 months and 28.9 months, respectively (p = 0.03), and mean stereopsis was 147 arcsec and 65 arcsec (p = 0.02). In patients with intermittent exotropia with DVD and infantile esotropia with DVD, the mean amount of DVD was 9.7(Delta) and 17.2(Delta), respectively (p < 0.01). Bielschowsky head-tilt test showed an increase of DVD on ipsilateral head tilt in 91% and 63.3%, respectively.
Intermittent exotropia with DVD is characterized by earlier onset of strabismus and worse stereopsis, suggesting that these factors may be related to the development of DVD in patients with intermittent exotropia. Unlike DVD in infantile esotropia, DVD in intermittent exotropia was smaller in amount and demonstrated a more uniform response to the Bielschowsky head-tilt test.
Journal of AAPOS: the official publication of the American Association for Pediatric Ophthalmology and Strabismus / American Association for Pediatric Ophthalmology and Strabismus 04/2008; 12(4):390-5. · 1.07 Impact Factor
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ABSTRACT: To investigate whether visual deficits in children with infantile spasm (IS) are the result of seizure activity or of treatment with the anticonvulsant drug vigabatrin (VGB).
Vision function was determined in three experiments by determining peak contrast sensitivity (CS) and grating acuity (GA) with the sweep visual evoked potential. Cross-sectional study A: 34 children, including 11 patients with childhood epilepsy with exposure to VGB for at least 6 months, 10 with childhood epilepsy exposed to antiepileptic drugs other than VGB, and 13 normally developing children. Cross-sectional study B: 32 children, including 16 with IS naïve to VGB and 16 normally developing children. Longitudinal study: seven children with IS naïve to VGB, with subsequent follow-up 5 to 10 months after starting VGB.
In cross-sectional study A, the median CS was reduced by 0.5 log units (P = 0.025) in children with epilepsy exposed to VGB compared with those exposed to other antiepileptic drugs and normally developing children. In cross-sectional study B, the median CS was reduced by 0.25 log units (P = 0.0015) in children with IS (VGB naïve) compared with normally developing children. Longitudinal assessment showed no decrease in CS in children with IS who were followed up 5 to 10 months after starting VGB. There was no difference in GA among groups in any of the experiments.
Patients with IS have CS deficits, but a sparing of GA. This deficit is present before VGB treatment and does not worsen with treatment onset. Results suggest that visual dysfunction is largely the result of the seizures themselves.
Investigative Ophthalmology & Visual Science 09/2007; 48(8):3610-5. · 3.60 Impact Factor
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British Journal of Ophthalmology 08/2007; 91(7):985-6. · 2.90 Impact Factor
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ABSTRACT: Neurofibromatosis type 1 (NF-1) is an autosomal dominant phakomatosis with a prevalence of 1 in 2000 to 1 in 5000. Up to 24% of these patients have optic pathway gliomas (OPGs). In the present study, the use of sweep visual evoked potentials (SVEPs) was investigated as a screening tool for identifying patients with NF-1 who had OPGs by comparing them to those patients with no OPGs and to normally developing children.
Contrast sensitivity and grating acuity were measured with the SVEP. Sixteen children with OPGs (OPG group), 14 children with NF-1 without OPGs (nOPG), and 16 aged-matched control subjects were recruited. All participants had best-corrected visual acuity of 6/9 or better. All were tested monocularly.
Comparisons between groups by using the Tukey B test showed a significant reduction of mean log contrast sensitivity in the OPG group (1.55) compared with the nOPG (1.9, P = 0.006) and control (2.10, P < 0.001) group. There was no significant difference between the nOPG and control groups (P = 0.195). Grating acuity was comparable between groups, and no statistically significant differences were found. Log contrast sensitivity was moderately sensitive in identifying patients with OPG and was highly specific in screening out patients with no OPG.
Children with OPGs have reduced contrast sensitivity when assessed using the SVEP. Children with no OPGs display no differences in visual functioning compared with control subjects. The findings suggest that the SVEP can be a useful and noninvasive screening tool for early detection of visual pathway gliomas in children with NF-1 and normal visual acuity.
Investigative Ophthalmology & Visual Science 07/2007; 48(6):2895-902. · 3.60 Impact Factor
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ABSTRACT: To ascertain the interobserver agreement among various specialists when analyzing images of the optic nerve head taken with the RetCam 120 (Clarity Medical Systems, Inc., Pleasanton, CA) for assessing the progression of optic disk cupping in pediatric glaucoma.
Five observers compared pairs of RetCam 120 two-dimensional photographs from 64 eyes to identify whether or not changes in the optic disk had occurred. Observers included a pediatric glaucoma specialist, pediatric neurophthalmologist, strabismologist, pediatric ophthalmic imaging specialist, and pediatric ophthalmology fellow. Each was masked to the patient identity and clinical course. For each patient, the observers reviewed the photographs taken prior to therapy and at a minimum of 6 months following initiation of therapy. Interobserver variability was calculated and analysis conducted to identify influential variables.
Poor agreement was noted between the observers. No significant association was obtained between agreement level and variables affecting photographic quality: variability of contrast and illumination, exposure and magnification, image clarity, presence of fluorescein on the cornea, and pixelation of the image with poor resolution. Raters noted problems with these image variables in 75.6% of the observations. The Kappa statistic obtained was kappa = 0.29 with overall proportion of agreement of p = 0.69, suggesting a fair agreement but not a moderate agreement.
Comparison of RetCam 120 pediatric optic nerve head photographs, when performed subjectively by observers with different perspectives, and in isolation from clinical information, may not be a reliable indicator of cupping change. In addition, variations in image contrast, luminance, color, and pixelation pose significant challenges to agreement between observers. Comparison of RetCam 120 images should not be considered the sole criterion for monitoring pediatric glaucoma.
Journal of American Association for Pediatric Ophthalmology and Strabismus 01/2007; 10(6):528-33. · 1.03 Impact Factor
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Journal of American Association for Pediatric Ophthalmology and Strabismus 11/2006; 10(5):489-90. · 1.03 Impact Factor
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ABSTRACT: To evaluate the accuracy of ultrasound biomicroscopy (UBM) for measuring the insertional distance from the limbus of horizontal extraocular muscles (EOM) that had previous surgery.
This prospective, masked, observational study compared the distance of the horizontal EOM insertion from the limbus as measured by 50-MHz UBM, either preoperatively or at the time of the anesthesia, with that measured by surgical caliper intraoperatively.
Forty-three horizontal rectus muscles in 23 subjects were measured using the UBM. Of these 43 muscles, 41 (22 medial rectus and 19 lateral rectus muscles) were successfully imaged by UBM and also received intraoperative surgical measurements. Two medial rectus muscles of one patient were inserted too far from the limbus (beyond 12 mm) to be detected by UBM. The mean measured distances of the horizontal muscle insertions from the limbus were 9.0 mm with UBM and 9.3 mm at surgery (P = 0.0001, showing no significant difference). For 33 (80.5%) of the muscles, the 2 methods agreed within 1 mm (P < 0.0001). There was no difference in accuracy for lateral rectus compared with medial rectus muscles or when comparing the muscles imaged by UBM under topical versus general anesthesia.
The 50-MHz UBM can accurately measure the horizontal EOM insertion distances from the limbus for muscles in patients that had previous surgery. The limit of detection was 12 mm from the limbus for the MR and 14 mm for the LR. Depending on the patient's age and level of cooperation, the UBM study can be done under either general anesthesia or topical anesthesia.
Journal of American Association for Pediatric Ophthalmology and Strabismus 07/2006; 10(3):202-5. · 1.03 Impact Factor
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ABSTRACT: To use visual evoked potential (VEP) testing to determine whether visual deficits are present in children with a history of vigabatrin use.
Contrast sensitivity and visual acuity were assessed by visual evoked potential testing and compared between 28 children (mean age, 4.90 +/- 4.92 years) with seizure disorders who had taken vigabatrin and 14 typically developing children (mean age, 3.14 +/- 1.70 years). Exclusion criteria were heritable eye disease, suspected cortical visual impairment, nystagmus, and prematurity >2 weeks. The effects of the following factors on contrast sensitivity and visual acuity were examined: type of seizure (infantile spasms versus other), ERG result, duration of vigabatrin therapy, cumulative dosage of vigabatrin, and other seizure medications (other versus no other medication).
Contrast sensitivity and visual acuity were reduced in vigabatrin-treated children with infantile spasms compared with vigabatrin-treated children with other seizure disorders and typically developing control subjects. The other factors examined had no significant effect on contrast sensitivity or visual acuity, with adjustment for seizure type.
Children with infantile spasms on vigabatrin may have compromised visual function, even in the absence of suspected cortical visual impairment. The children tested in the present study have reduced vision, probably associated with infantile spasms rather than vigabatrin.
Investigative Ophthalmology & Visual Science 03/2005; 46(2):514-20. · 3.60 Impact Factor
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ABSTRACT: To describe the clinical pattern of retinal atrophy in children caused by the anticonvulsant vigabatrin.
An interventional case series report.
One hundred thirty-eight patients, mainly infants, were evaluated regularly for evidence of possible vigabatrin toxicity in the Eye and Neurology clinics at the Hospital for Sick Children, Toronto.
Sequential clinical and electroretinographic (International Society for Clinical Electrophysiology of Vision standards) evaluations every 6 months.
Presence of recognizable retinal and optic atrophy in the presence of abnormal electroretinogram (ERG) and other clinical findings.
Three children being treated for seizures with vigabatrin showed definite clinical findings of peripheral retinal nerve fiber layer atrophy, with relative sparing of the central or macular portion of the retina and relative nasal optic nerve atrophic changes. Some macular wrinkling was evident in 1 case. Progressive ERG changes showing decreased responses, especially the 30-Hz flicker response, supported the presence of decreased retinal function.
A recognizable and characteristic form of peripheral retinal atrophy and nasal or "inverse" optic disc atrophy can occur in a small number of children being treated with vigabatrin. The changes in superficial light reflexes of the retina in children facilitate the clinical recognition of nerve fiber layer atrophy. The macula is relatively spared, although superficial retinal light reflexes indicating wrinkling of the innermost retina suggest early macular toxicity as well. Because these changes are accompanied by electrophysiologic evidence of retinal dysfunction, discontinuation of vigabatrin should be strongly considered.
Ophthalmology 11/2004; 111(10):1935-42. · 5.45 Impact Factor
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Canadian Journal of Ophthalmology 03/2004; 39(1):77-9. · 1.47 Impact Factor
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ABSTRACT: Vigabatrin (gamma-vinyl-GABA) is an antiepileptic drug successful in the management of infantile spasms. Photopic ERGs were tested in children followed longitudinally before and during vigabatrin treatment.
Subjects were 26 infants (age range 1.5-24 months, median 7.6 months) on vigabatrin treatment who had been tested on multiple visits (two to four visits; mean, three visits). Eighteen of these were assessed initially before starting vigabatrin therapy and eight were assessed within 1 week of initiation of the drug. ERGs were recorded at 6-month intervals. Standard ISCEV protocol with Burian-Allen bipolar contact-lens electrodes (standard flash 2.0 cd.s/m2) was used. Although ISCEV standards were followed, a higher flash intensity (set at 3.6 cd.s/m2) was chosen for single-flash cone assessment to provide a better definition of OPs. Photopic OPs were divided into categories of early OPs and late OP (OP4). Responses were compared with age corrected limits extrapolated from our lab control database.
Results showed differential effects of vigabatrin on the summed early OP amplitudes versus the late OP (OP4) and cone b-wave amplitude. The early OPs showed significant decrease (p = 0.0005, repeated measures analysis of variance) after 6 months and remained decreased for the duration of treatment. There was no significant change seen in the late OP. The cone b-wave amplitude showed initial increase (p = 0.04) after 6 months, followed by a decrease after 18 months; a trend similar to that of the late OP.
Early photopic OPs were disrupted more than the late OP, suggesting relative deficit in the ON (depolarizing) retinal pathways.
Documenta Ophthalmologica 12/2003; 107(3):289-97. · 2.11 Impact Factor
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ABSTRACT: Electroretinograms (ERGs) have been recorded longitudinally in children before and during treatment with the antiepileptic drug vigabatrin for the past 3.5 years. Vigabatrin induced changes in ERG responses occur in children; the most dramatic changes occur in the oscillatory potentials. The purpose of this study was to identify changes in ERG responses associated with discontinuation of vigabatrin treatment. If vigabatrin-induced changes reverse after discontinuation of the drug we infer that the original change is not an indicator of toxicity. ERG data were analyzed from 17 children who discontinued vigabatrin therapy. The duration of treatment ranged from 5 to 52 months, the age for the first ERG ranged from 6 to 38 months (median 10 months). ERGs were tested using the standard protocol established by the International Society for Clinical Electrophysiology of Vision, with Burian-Allen bipolar contact-lens electrodes. In addition to standard responses we recorded photopic oscillatory potentials (OPs). During vigabatrin treatment OPs show a greater change than other ERG responses, with the early occurring wavelets from the photopic OPs showing the greatest change. With discontinuation of vigabatrin the amplitude of the early wavelets of the photopic OPs increased dramatically compared with amplitudes while taking the drug (paired t-test, p = 0.000075). The scotopic oscillatory potentials also show some recovery. Although changes in oscillatory potentials may occur with vigabatrin toxicity, a large change likely occurs with a non-toxic pharmacological effect of vigabatrin on GABAergic amacrine cells in the inner plexiform layer. Reduction of OPs in children on vigabatrin may not be related to toxicity.
Documenta Ophthalmologica 12/2003; 107(3):299-309. · 2.11 Impact Factor
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ABSTRACT: To evaluate the usefulness of routine ophthalmic examination before renal transplantation in children.
We reviewed the records of ophthalmic assessments of renal transplant recipients at The Hospital for Sick Children, Toronto, Ont., from January 1989 to June 1996. If abnormalities had been found, we determined whether they had previously been documented, were related to the renal disease or other systemic disease, had required intervention or had affected visual function. We calculated the maximum statistical chance of detecting a meaningful eye problem at the pretransplantation assessment. We also estimated the direct cost of the ophthalmic assessment and the effect, if any, of the findings on the patient's medical management.
We included 107 charts. Before the ophthalmic assessment, 32 patients (30%) had known eye problems. The ocular examination detected abnormalities in 46 patients (43%); the abnormalities had not been detected previously in 14 (13%). New, potentially vision-threatening eye disorders were found in 6 (6%) of the patients. No finding affected the short- or long-term management of any patient.
Children with chronic renal failure had a high prevalence of ocular abnormalities, but most of the abnormalities did not affect visual function. Although ophthalmic assessment before transplantation did not alter the medical management of the renal transplant patients, consultation may be helpful in selected patients, particularly those who are not already under the care of an optometrist or ophthalmologist and those who have a visual complaint.
Canadian Journal of Ophthalmology 09/2003; 38(5):379-84. · 1.47 Impact Factor
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ABSTRACT: To report our retrospective study of 20 cases with lissencephaly and describe ocular and visual abnormalities associated with this disorder.
Patients with lissencephaly were identified and classified into classic (type I) or cobblestone (type 2) lissencephaly on the basis of a review of clinical records and neuroimaging studies. Only patients examined by an ophthalmologist were included in the study.
Only 1 patient had a normal ocular examination. Ocular abnormalities included optic nerve hypoplasia and atrophy, retinal dysplasia, retinal nonattachment, macular hypoplasia, anterior segment malformation, and strabismus.
Ocular abnormalities in classic (type 1) lissencephaly are less severe. Central, steady, and maintained fixation may be present despite the presence of optic nerve hypoplasia, optic atrophy, macular hypoplasia, strabismus, or refractive errors. Retinal and anterior segment abnormalities were observed only in cobblestone (type 2) lissencephaly. These patients often have severe visual impairment because of retinal or cortical disease.
Journal of American Association for Pediatric Ophthalmology and Strabismus 07/2003; 7(3):178-84. · 1.03 Impact Factor
