A case of reduplication of the lens with uveal coloboma is described. This is a rare condition and, unlike the two previously reported cases, the other ocular structures and adnexae appeared normal. (+info)
Clinical characteristics of CHARGE syndrome.
CHARGE syndrome, first described by Pagon, was named for its six major clinical features. They are: coloboma of the eye, heart defects, atresia of the choanae, retarded growth and development including CNS anomalies, genital hypoplasia and/or urinary tract anomalies, and ear anomalies and/or hearing loss. We experienced three cases of CHARGE syndrome who displayed ocular coloboma, heart defects, retarded growth and development, and external ear anomalies, and we also review the previously reported literature concerning CHARGE syndrome. (+info)
Looking behind a pathological blind spot in human retina.
Recent work suggests that dichoptic lateral interactions occur in the region of the visual field of one eye that corresponds to the physiological blind spot in the other eye (Tripathy, S. P., & Levi, D. M. (1994). The two-dimensional shape of spatial interaction zones in the parafovea. Vision Research, 34, 1127-1138.) Here we ask whether dichoptic lateral interactions occur in the region of the visual field of one eye that corresponds to a pathological blind spot, a retinal coloboma in the other eye. To address this question we had the observer report the orientation of a letter 'T' presented within this region in the presence of flanking 'T's presented to the other eye around the coloboma. A large drop in performance was seen due to the flanks, showing the existence of dichoptic lateral interactions in this monocular region. The presence of these dichoptic interactions in a region lacking direct retinal afferents from one eye is consistent with the proposition that long-range horizontal connections of the primary visual cortex mediate these interactions. (+info)
Demonstration of exclusive cilioretinal vascular system supplying the retina in man: vacant discs.
PURPOSE: To report the fluorescein angiographic and Doppler ultrasonographic findings in a patient with apparent exclusive ciliary vascular supply of the retina of both eyes. METHODS: Case report. RESULTS: The ophthalmoscopic appearance of all arterial vessels emanating from both discs was consistent with a cilioretinal origin. Retinal veins also entered each disc peripherally near the margin, leaving the central part of each disc vacant. Fluorescein angiography showed filling of all arterial vessels simultaneous with the early-phase choroidal background flush bilaterally. Color and power Doppler ultrasonographic imaging demonstrated unequivocally the absence of central retinal vessels within the optic nerves. Both discs were normal in size and excavated with central glial tissue present. The clinical history of monocular, alternating episodes of failing vision with partial resolution and the retinal pigmentation patterns bilaterally were consistent with, though not conclusive for, previous episodes of serous retinal detachments. Coincident systemic anomalies consisted of small kidneys with reduced renal parenchyma discovered on ultrasonography, along with chronic interstitial nephritis. CONCLUSIONS: The ophthalmoscopic appearance of optic discs with apparent all-cilioretinal vascular supply has been reported previously, but proof of the absence of central retinal vessels requires Doppler ultrasonographic evidence corroborated by angiographic findings, as exemplified in our case report. We describe the association of this disc anomaly with renal parenchymal disease and its distinction from colobomatous defects. (+info)
Dysgenesis of the internal carotid artery associated with transsphenoidal encephalocele: a neural crest syndrome?
We describe two original cases of internal carotid artery dysgenesis associated with a malformative spectrum, which includes transsphenoidal encephalocele, optic nerve coloboma, hypopituitarism, and hypertelorism. Cephalic neural crest cells migrate to various regions in the head and neck where they contribute to the development of structures as diverse as the anterior skull base, the walls of the craniofacial arteries, the forebrain, and the face. Data suggest that the link between these rare malformations is abnormal neural crest development. (+info)
Pax2 in development and renal disease.
Pax genes are associated with a variety of developmental mutations in mouse and man that are gene dosage sensitive, or haploinsufficient. The Pax2 gene encodes a DNA binding, transcription factor whose expression is essential for the development of the renal epithelium. Both gain and loss of function mutants in the mouse demonstrate a requirement for Pax2 in the conversion of metanephric mesenchymal precursor cells to the fully differentiated tubular epithelium of the nephron. However, Pax2 expression is down-regulated as cells leave the mitotic cycle. Humans carrying a single Pax2 mutant allele exhibit renal hypoplasia, vesicoureteric reflux, and optic nerve colobomas. Conversely, persistent expression of Pax2 has been demonstrated in a variety of cystic and dysplastic renal diseases and correlates with continued proliferation of renal epithelial cells. Thus, Pax2 misexpresssion may be a key determinant in the initiation and progression of renal diseases marked by increased or deregulated cell proliferation. (+info)
Bitemporal pseudohemianopia related to the "tilted disk" syndrome: CT, MR, and fundoscopic findings.
We describe a case of the "tilted-disk" syndrome in a patient with a bitemporal field depression (a pseudohemianopia). CT and MR imaging showed thinning and prolapse of the nasal sectors of the posterior walls of the globes and flattening of the temporal portion of the globes. (+info)
The homeodomain protein vax1 is required for axon guidance and major tract formation in the developing forebrain.
The homeodomain protein Vax1 is expressed in a highly circumscribed set of cells at the ventral anterior midline of the embryonic CNS. These cells populate the choroid fissure of the optic disk, the body of the optic stalk and nerve, the optic chiasm and ventral diencephalon, and the anterior midline zones that abut developing commissural tracts. We have generated mutant mice that lack Vax1. In these mice (1) the optic disks fail to close, leading to coloboma and loss of the eye-nerve boundary; (2) optic nerve glia fail to associate with and appear to repulse ingrowing retinal axons, resulting in a fascicle of axons that are completely segregated from optic nerve astrocytes; (3) retinal axons fail to penetrate the brain in significant numbers and fail to form an optic chiasm; and (4) axons in multiple commissural tracts of the anterior CNS, including the corpus callosum and the hippocampal and anterior commissures, fail to cross the midline. These axon guidance defects do not result from the death of normally Vax1(+) midline cells but, instead, correlate with markedly diminished expression of attractive guidance cues in these cells. Vax1 therefore regulates the guidance properties of a set of anterior midline cells that orchestrate axon trajectories in the developing mammalian forebrain. (+info)