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Results for “MICROPHTHALMOS”

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At least 721 records · Page 40Linked to original sources
PubMed2005

EMX homeobox genes regulate microphthalmia and alter melanocyte biology.

Melanocytes are specialized cells that produce melanin, the pigment responsible for skin, hair and retina color. They derive during embryogenesis from the precursor cells melanoblasts, which are neural crest cells committed to the pigment cell lineage. The differentiation of melanoblasts into melanocytes involves the expression of melanocyte-specific genes, particularly those responsible for melanin production, such as Tyr, Tyrp-1 and Dct, the expression of which depends on the melanocyte-specific transcription factor microphthalmia (Mitf). We have developed and executed a functional screen on melanocytes, with the aim of identifying genes involved in pigment cell biology. We have found Emx1 and Emx2, two highly related homeobox genes that when overexpressed in melanocytes can downregulate Mitf, Tyrp1, Dct and Tyr. Constitutive expression of Emx alters pigment cell morphology and growth properties: it confers TPA independence but not the ability to grow in soft agar. Spatial and temporal expression of Emx and Mitf during embryonic development suggests that Emx could be one factor that regulates correct expression of Mitf by inhibiting its activation in neuroepithelial derivatives other than melanocytes.

Animals↗
PubMed1990

Laser and unsutured sclerotomy in nanophthalmos.

Among 30 eyes with nanophthalmos, 21 had angle-closure glaucoma and two had open-angle glaucoma associated with pseudoexfoliation of the lens capsule. Laser iridotomies, sometimes combined with laser iridoplasty, were sufficient to control, or to allow medical control of, the glaucoma in 15 of 18 eyes. Four eyes with uveal effusion underwent an unsutured sclerotomy or sclerectomy, and all had resolution of the choroidal detachment within two weeks. Cataract extraction improved the vision in seven of nine eyes. Previous or simultaneous sclerotomy or sclerectomy was performed on all nine eyes that underwent cataract extraction and in two eyes at the time of glaucoma surgery; no eye had postoperative uveal effusion or other major complications. Laser iridotomy and iridoplasty, sometimes with supplemental medical therapy, are often sufficient in the treatment of angle-closure glaucoma in nanophthalmos and are safer than surgery. Nanophthalmic uveal effusion can be prevented or treated with an unsutured sclerotomy or sclerectomy.

Adolescent↗
PubMed1996

Posterior segment neovascularization associated with optic nerve aplasia.

PURPOSE: To report the presence of posterior segment neovascularization in eyes with optic nerve aplasia. METHODS: Three eyes in two patients with clinical optic nerve aplasia were studied. RESULTS: Examination disclosed posterior segment neovascularization in one eye and progressive posterior segment neovascularization in two eyes. CONCLUSIONS: Posterior segment neovascularization may occur in association with optic nerve aplasia. Retinal ischemia or retinochoroidal anatomic disorganization, or both, may provide the stimulus for neovascularization in such eyes.

Coloboma↗
PubMed1985

Unilateral esotropia after enucleation in infancy.

Five patients developed esotropia in the remaining eye after unilateral enucleation in the first few weeks to months of life. Esotropia was associated with a face turn toward the opposite side and abduction nystagmus with a null point in extreme adduction. Our experience with these patients supports the reflexogenic theory for the development of a type of congenital-infantile esotropia. An intact globe-ocular muscle relationship, even in a blind eye, may have a stabilizing effect on the fellow eye in the first few weeks to months of life, and this should be considered before enucleation is done.

Cataract Extraction↗
PubMed1978

Hydrocephaly, congenital retinal nonattachment, and congenital falciform fold.

A 6-year-old boy, whose parents were first cousins, had congenital retinal nonattachment in one eye and a falciform fold in the other. He had had a shunt operation for hydrocephaly. Oxygen was never administered and test results for rubella and toxoplasmosis were negative. The consanguinity in this case indicates the syndrome is an autosomal recessive trait. This and other hereditary disorders with congenital retinal nonattachment have previously been misinterpreted as retrolental fibroplasia occurring without oxygen treatment.

Child↗
PubMed1992

Hereditary microphthalmia with colobomatous cyst.

We examined five members of a highly inbred kinship who had isolated microphthalmia associated with colobomatous cysts and various other ocular lesions. They were all offspring of consanguineous (first cousins) and unaffected parents. Microphthalmia in this kindred was transmitted as an autosomal recessive trait. Ultrasonography was effective for prenatal diagnosis in two pregnancies at risk.

Child↗
PubMed1998

Bilateral secondary angle-closure glaucoma as a complication of anticoagulation in a nanophthalmic patient.

PURPOSE: To describe bilateral hemorrhage of the posterior segment and secondary angle-closure glaucoma as sequelae of anticoagulation therapy in a nanophthalmic patient. METHODS: An 80-year-old man who was nanophthalmic and was undergoing anticoagulation therapy presented with declining visual acuity in left eye. Six months later, he experienced declining visual acuity in his right eye. RESULTS: In the LE and six months later in the RE, ocular examination disclosed angle-closure glaucoma and a hemorrhagic retinal detachment. Peripheral iridoplasty successfully treated the initial attack. The subretinal hemorrhage was successfully drained by pars plana vitrectomy, retinotomy, and air-fluid exchange in the left eye. Anatomic success and intraocular pressure control were obtained, but visual recovery was limited. CONCLUSION: Intraocular hemorrhage and angle-closure glaucoma are potential complications of anticoagulation therapy in a patient with nanophthalmos.

Aged↗
PubMed1999

Abnormal collagen fibrils in nanophthalmos: a clinical and histologic study.

PURPOSE: To report the successful treatment of choroidal detachment in a patient with nanophthalmos and to report histopathologic findings in this patient's sclera. METHODS: Choroidal detachment, secondary angle closure, and nanophthalmos were diagnosed using biomicroscopy, indirect ophthalmoscopy, and echography. Full-thickness sclerectomies in four quadrants were made on the right eye. Sclerae from these sclerectomies were studied ultrastructurally. RESULTS: Best-corrected visual acuity improved to RE, 20/60 from 20/100 preoperatively; the anterior chamber deepened, and the choroidal detachment resolved. Histopathologic studies of each of the three scleral layers disclosed abnormal collagen fibrils that were frayed, split, and contained lightly stained cores. CONCLUSION: New findings include the identification of collagen with lightly stained centers and identification of differences in collagen morphology in different areas of the sclera in a nanophthalmic eye.

Adult↗
PubMed1999

Familial exudative vitreoretinopathy mimicking persistent hyperplastic primary vitreous.

PURPOSE: To report an unusual case of familial exudative vitreoretinopathy in an infant. METHODS: Case report. A 6-day-old girl had unilateral microphthalmia in the right eye, with a retrolental plaque initially diagnosed as persistent hyperplastic primary vitreous. Three months later, peripheral retinal vascular changes and a fibrovascular ridge were noted in the left eye, suggesting familial exudative vitreoretinopathy as the cause in both eyes. RESULTS: The microphthalmic right eye was unsalvageable. The left eye developed an exudative retinal detachment despite photocoagulation of the peripheral avascular retina. Additional cryotherapy resulted in resolution of the detachment and regression of the vascular changes. CONCLUSIONS: With highly asymmetric involvement, neonatal familial exudative vitreoretinopathy can mimic persistent hyperplastic primary vitreous. Fellow eye involvement can progress rapidly.

Cryotherapy↗
PubMed2005

Vascular endothelial growth factor expression in the retinal pigment epithelium is essential for choriocapillaris development and visual function.

The choroid in the eye provides vascular support for the retinal pigment epithelium (RPE) and the photoreceptors. Vascular endothelial growth factor (VEGF) derived from the RPE has been implicated in the physiological regulation of the choroidal vasculature, and overexpression of VEGF in this epithelium has been considered an important factor in the pathogenesis of choroidal neovascularization in age-related macular degeneration. Here, we demonstrate that RPE-derived VEGF is essential for choriocapillaris development. Conditional inactivation of VEGF expression in the RPE (in VEGFrpe-/- mice) results in the absence of choriocapillaris, occurrence of microphthalmia, and the loss of visual function. Severe abnormalities of RPE cells are already observed when VEGF expression in the RPE is only reduced (in VEGFrpe+/- mice), despite the formation of choroidal vessels at these VEGF levels. Finally, using Hif1arpe-/- mice we demonstrate that these roles of VEGF are not dependent on hypoxia-inducible factor-1alpha-mediated transcriptional regulation of VEGF expression in the RPE. Thus, hypoxia-inducible factor-1alpha-independent expression of VEGF is essential for choroid development.

Animals↗
PubMed2005

Anophthalmia and microphthalmia in the Alberta Congenital Anomalies Surveillance System.

BACKGROUND: A higher than expected rate of anophthalmia/microphthalmia (A/M) for 1999 was noted in both the Alberta Congenital Anomalies Surveillance System (ACASS) and the Canadian Congenital Anomalies Surveillance System (CCASS). Since this increase was at variance with the previous 19 years, we performed a review to determine whether the increase was true and, if so, the possible explanation. METHODS: We reviewed the records of the cases of A/M in the ACASS together with the accompanying attachments (e.g., consultant, autopsy and chromosome reports) for 1991-2001. In addition, we contacted all 91 registered ophthalmologists in Alberta. Letters were also written to the Edmonton and Calgary offices of the Canadian National Institute for the Blind (CNIB). RESULTS: Sixty cases of A/M were ascertained over the study period. Of the 88 active ophthalmologists in the province, 21 (24%) replied, but no new cases were ascertained from this source. No replies were received from the CNIB. We constructed five categories of clinical phenotypes for the 60 cases: 20 had a chromosomal etiology, 13 had a recognized syndrome or association, 16 had extraocular malformations, 5 had other eye anomalies, and 6 had A/M only. Pregnancy terminations were not included. The higher rate in 1999 was mainly due to cases with a chromosomal etiology or a recognized syndrome or association. There was no indication that a teratogen was causing a cluster of A/M cases, as our annual rates were comparable to those for other jurisdictions not only in Canada but also in other countries. INTERPRETATION: Our review confirmed that the rate of A/M in Alberta in 1999 was high but that the increase was mainly due to five cases of trisomy 13 together with one case associated with a syndrome (Meckel-Gruber). Our findings provide reassurance that there was no environmental cause of clustering of anophthalmia or microphthalmia. This review demonstrates the importance of ongoing population-based surveillance in providing baseline birth prevalence rates for evaluating trends and clusters.

Alberta↗
PubMed1992

The effect of the microphthalmia gene on pre-natal optic nerve development in the mouse.

The purpose of this study was to examine the effect of the microphthalmia gene on pre-natal optic nerve development in the mouse. Coronal serial sections of wild-type, heterozygote and homozygous microphthalmic embryonic optic nerves are examined throughout gestation. No obvious morphological abnormality was identified in the heterozygote. The microphthalmic optic stalk/nerve was larger than that of the wild-type and heterozygote and there was persistence of the optic stalk throughout gestation. This was due to a high mitotic rate and reduced cell death in the dorsal layer of the microphthalmic optic stalk as well as persistence of the optic ventricle throughout gestation. The latter was associated with persistence of intermediate-type junctions between the neuroepithelial cells lining the ventricle and failure of the cells on the dorsal aspect of the distal stalk to degenerate. Possible mechanisms for the disappearance of the optic ventricle in the normal optic stalk are suggested.

Animals↗