Terry L. Schwartz

Voxel-based analysis of MRI detects abnormal visual cortex in children and adults with amblyopia

Amblyopia, sometimes called “lazy eye,” is a relatively common developmental visual disorder well characterized behaviorally; however, the neural substrates associated with amblyopia in humans remain unclear. We hypothesized that abnormalities in the cerebral cortex of subjects with amblyopia exist, possibly as a result of experience‐dependent neuronal plasticity. Anatomic magnetic resonance imaging (MRI) and psychophysical vision testing was carried out on 74 subjects divided into two age ranges, 7–12 years and 18–35 years, and three diagnoses, strabismic amblyopia, anisometropic amblyopia, and normal vision. We report a behavioral impairment in contrast sensitivity for subjects with amblyopia, consistent with previous reports. When the high‐resolution MRI brain images were analyzed quantitatively with optimized voxel‐based morphometry, results indicated that adults and children with amblyopia have decreased gray matter volume in visual cortical regions, including the calcarine sulcus, known to contain primary visual cortex. This finding was confirmed with a separate region‐of‐interest analysis. For the children with amblyopia, additional gray matter reductions in parietal‐occipital areas and ventral temporal cortex were detected, consistent with recent reports that amblyopia can result in spatial location and object processing deficits. These data are the first to provide possible neuroanatomic bases for the loss of binocularity and visual sensitivity in children and adults with amblyopia. Hum Brain Mapp 25:222–236, 2005.

Tyrosinemia type II: nine cases of ocular signs and symptoms.

PURPOSE To report nine cases of tyrosinemia type II, with ocular signs and symptoms. METHODS Participants included nine patients (18 eyes) who were followed for a mean follow-up period of 6.5 years (range, 2 to 8 years). Intervention included dietary restriction of tyrosine and phenylalanine, which led to resolution of ocular and cutaneous lesions, improved behavior in one patient, and may have prevented developmental delay in others. The main outcome measures were visual acuity and serum tyrosine levels to determine the response to dietary therapy. Intelligence testing and developmental screening were performed when appropriate. RESULTS All patients presented with ocular signs and symptoms as the primary manifestation of disease and serve to illustrate the typical ocular findings of this syndrome. Three patients presented with cutaneous manifestations, and one patient had mild mental impairment at the time of diagnosis. CONCLUSIONS Recalcitrant pseudodendritic keratitis may be the presenting sign in tyrosinemia type II. Awareness of the presenting signs and symptoms may accelerate the diagnosis and dietary intervention. Initiation of a tyrosine-restricted and phenylalanine-restricted diet in infancy is most effective in preventing cognitive impairment.

Retinotopic maps and foveal suppression in the visual cortex of amblyopic adults

Amblyopia is a developmental visual disorder associated with loss of monocular acuity and sensitivity as well as profound alterations in binocular integration. Abnormal connections in visual cortex are known to underlie this loss, but the extent to which these abnormalities are regionally or retinotopically specific has not been fully determined. This functional magnetic resonance imaging (fMRI) study compared the retinotopic maps in visual cortex produced by each individual eye in 19 adults (7 esotropic strabismics, 6 anisometropes and 6 controls). In our standard viewing condition, the non‐tested eye viewed a dichoptic homogeneous mid‐level grey stimulus, thereby permitting some degree of binocular interaction. Regions‐of‐interest analysis was performed for extrafoveal V1, extrafoveal V2 and the foveal representation at the occipital pole. In general, the blood oxygenation level‐dependent (BOLD) signal was reduced for the amblyopic eye. At the occipital pole, population receptive fields were shifted to represent more parafoveal locations for the amblyopic eye, compared with the fellow eye, in some subjects. Interestingly, occluding the fellow eye caused an expanded foveal representation for the amblyopic eye in one early–onset strabismic subject with binocular suppression, indicating real‐time cortical remapping. In addition, a few subjects actually showed increased activity in parietal and temporal cortex when viewing with the amblyopic eye. We conclude that, even in a heterogeneous population, abnormal early visual experience commonly leads to regionally specific cortical adaptations.

Charles Bonnet syndrome in children

Charles Bonnet syndrome (CBS) is characterized by the presence of complex visual hallucinations in psychologically healthy but visually impaired people. It has been well described in the adult population but has been less well characterized in children. This report describes CBS in 2 children, both of whom had diagnoses of cone-rod dystrophy. After previously normal visual experience, each underwent rapid visual deterioration between 6 and 8 years old. Formed visual hallucinations were noted shortly after loss of vision. The childrens symptoms were identical to those described by adults with CBS. Formed visual phenomena included geometric shapes, people, and buildings. Images, which were both stationary and in motion, were described as interesting or entertaining and only rarely as frightening. No other senses were affected (no auditory component). Sixteen additional children with diseases of the eye or optic nerves were questioned about symptoms of CBS, including children with congenitally decreased vision, children with slowly progressive visual loss but current vision better than 20/200, and children with early normal vision who had profound vision loss before 4 years old; all these children denied hallucinations.

Management of oculus fragilis in Ehlers-Danlos type VI.

Purpose. To describe an alternative, novel surgical approach to the repair of a ruptured globe in the second reported patient with keratoglobus, Ehlers–Danlos type VI, and normal lysyl hydroxylase. Methods. Under general anesthesia, a 360° conjunctival peritomy was performed and the epithelium was removed from the keratoglobus cornea. Descemets membrane and endothelium were removed from a fresh donor corneoscleral ring. An onlay epikeratoplasty was then performed and the entire donor corneoscleral button was secured to the sclera with 9-0 nylon suture. The conjunctiva was brought into position and tacked down over the edge of the donor graft. After 4 months, a full-thickness penetrating keratoplasty was then performed. Results. The patient ultimately had a ruptured globe in the fellow eye and thus required the identical procedure OU. Both eyes were successfully repaired with a final visual acuity OU of 20/100. Conclusion. The described surgical approach allowed successful surgical repair of bilateral ruptured globes in a patient with keratoglobus, Ehlers–Danlos type VI, and normal lysyl hydroxylase levels. In the previous report of such a patient by Judisch et al. (1), the attempt at surgical repair was unsuccessful and ended in enucleation. The described surgical technique may be used to treat advanced keratoglobus or oculus fragilis.

Unilateral Megalencephaly and Tuberous Sclerosis: Related Disorders?

Case Report The patient, a white female newborn, was the first live-bom child of a 28year-old woman who experienced six prior miscarriages. The mother has tuberous sclerosis, as indicated by hypomelanotic macules, cortical tubers, and subependymal nodules. Her chronic seizure disorder was controlled throughout the pregnancy by phenytoin and phenobarbital. The pregnancy was complicated by maternal hypertension and gestational diabetes managed with diet. The infant was delivered by cesarean section at 39 weeks. Birth weight was 3800 g, and Apgar scores were 4 at 1 minute and 8 at 5 minutes.

Hypoplastic Corpus Callosum in Ocular Albinism: Indication of a Global Disturbance of Neuronal Migration

Ocular albinism is distinguished from the more common oculocutaneous albinism by the presence of normal pigmentation of skin and hair in the former condition. Recent studies of ocular albinism have shown that the hypopigmentation of the optic fundus is associated with a number of anomalies of neuronal wiring involving the visual system. We present a patient with ocular albinism who also has a hypoplastic corpus callosum as determined by analysis of midsagittal magnetic resonance imaging scans. Previous studies of the hypoplastic corpus callosum indicate that this anomaly is a defect in neuronal migration as well. The finding of a hypoplastic corpus callosum in a patient with ocular albinism suggests a more generalized defect in neuronal migration not limited to the visual system. (J Child Neurol 1990;5:341-343).

Health-related quality of life after surgical removal of an eye.

Purpose: This study compared the general health-related quality of life (HRQOL) and the vision-specific HRQOL in patients following the surgical removal of 1 eye who had good vision in the remaining eye to a group of binocular patients with good vision in OU. Methods: The Medical Outcomes Study Short Form 12 and the National Eye Institute Visual Function Questionnaire HRQOL surveys were administered to 29 patients who had surgical removal of an eye who attended an ocular prosthetics clinic and to 25 binocular persons who accompanied a patient. All subjects in each group had best-corrected visual acuity of 20/40 or better. Overall statistical significance was tested using Cramer’s V followed by individual t tests for independent groups for each of the scales on the 2 questionnaires to determine whether the means between the 2 groups differed statistically. Results: The patient group had a mean age of 50.98 years (range, 19–76 years). The control group had a mean age of 49.46 years (range, 18–76 years). The mean time after loss of vision was 28.03 years (range, 1–71 years), and the mean time from surgical removal of the eye was 23.6 years (range, 0.5–59.5 years). There was an overall significant difference between the 2 groups on the 15 derived subscales of the 2 forms (Cramer’s V, p = 0.0025). Three general HRQOL subscales (Short Form 12-mental component summary, Short Form 12 physical component summary, and National Eye Institute Visual Function Questionnaire-General Health) showed no differences between the 2 groups (p = 0.48, p = 0.81, and p = 0.78, respectively). Three of the 12 vision-specific National Eye Institute Visual Function Questionnaire subscales demonstrated statistically significant differences between the patient and control groups: peripheral vision (p = 0.0006), role difficulties (p = 0.015), and the composite score (p = 0.014). In addition, 2 monocular patients had given up driving compared with no binocular subjects (p = 0.056). Conclusions: This population of monocular patients had general physical and mental HRQOL equivalent to the normal binocular group despite the surgical removal of 1 eye. However, the reduced vision-specific HRQOL of monocular patients on the National Eye Institute Visual Function Questionnaire indicates that there are substantial residual visual deficits even after prolonged monocular status.

Congenital intraocular teratoma associated with eyelid coloboma.

PURPOSE To describe the first case of intraocular teratoma associated with eyelid coloboma and the second reported case of intraocular teratoma. DESIGN Interventional case report. METHODS A left intraocular tumor was surgically resected from a 2-day-old female with an associated lower eyelid coloboma. RESULTS Pathologic evaluation revealed a completely intraocular tumor comprising derivatives of all three germ cell layers giving a diagnosis of intraocular teratoma. The eyelid coloboma was repaired, and a scleral-wrapped hydoxyapatite-integrated orbital implant was placed. CONCLUSION To our knowledge, this is the second reported instance of teratoma originating within the globe and the only reported case of teratoma associated with eyelid coloboma. Although exceedingly rare, intraocular teratoma should be added to the differential diagnosis of congenital intraocular tumors.