Biomedical subjects
G R Beauchamp
Publications and source records attributed to G R Beauchamp.
Congenital glaucoma and other ocular abnormalities associated with pericentric inversion of chromosome 11.
Pericentric inversion of chromosome 11 occurred in consecutive generations of family members with congenital glaucoma. Affected persons were characterized by unilateral or bilateral congenital glaucoma, bilateral corneal disease, and a lack of appreciable dysmorphism. Previous reports of inversions of chromosome 11 are rare, and no ocular abnormalities have been noted. Chromosomal abnormalities may be the cause of some forms of congenital glaucoma and should be included in the genetic heterogeneity of this disease.
Causes of visual impairment in children.
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Inheritance of Fuchs' combined dystrophy.
The inheritance pattern of Fuchs' combined corneal dystrophy is not confirmed. Published pedigrees fail to demonstrate a 50% segregation and sex ratio. They include no more than two generations of affected individuals and indicate a strong, female predilection. The pedigree we will present shows 16 affected persons in four generations. The ratio of affected to unaffected and men to women is 1:1. Penetrance is apparently 100%. Nine of the affected are under 50 years of age; four are subteen age. Light and electron micrographs of corneal tissue from three patients in three different generations are consistent with the diagnosis of Fuchs' dystrophy. Fuchs' dystrophy can therefore be established as a classic autosomal dominant pattern.
Filtering surgery in children: barriers to success.
The use of trabeculectomy in advanced pediatric glaucoma is reviewed. Intraocular pressure was controlled in only 50% of the patients, and the best visual results was 20/200. Complications of vitreous loss, scleral collapse, ectasia, retinal detachment, and endophthalmitis were encountered. No evidence was found to support the claim that in the seriously compromised buphthalmic eyes, trabeculectomy is safer than other filtering operations since it filters under a scleral flap.
Background information: learning disabilities, dyslexia, and vision.
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Pediatric keratoplasty: problems in management.
A summary of experience in pediatric keratoplasty is given by adding ten recent cases to a previous report. A review of keratoplasty in infants and children from the literature generally recommends the procedure as safe and effective. Recent reports, however, cast some doubt on the effectiveness of the procedure for certain conditions. An update of experience is given as a focal point for a discussion of problems in clinical management of children who undergo keratoplasty. These problems are arbitrarily separated by pre-, intra-, and postoperative time frames.
Anterior segment dysgenesis keratolenticular adhesion and aniridia.
Three additional cases of keratolenticular adhesion and aniridia have been reported. A review of the embryology and terminology in the description of complex lesion of the anterior segment might suggest the more general phrase, anterior segment dysgenesis, to have advantage. Finally, the simultaneous occurrence of anterior segment anomalies and hemophilia is reported.
Blepharophimosis and cardiopathy.
A 2 1/2-year-old girl with blepharophimosis and ventriculoseptal defect is described. Blepharophimosis is rare, and this complex more so. Yet, the clinical implications of its recognition are potentially important.
Brown's syndrome in twins.
Monozygotic twin girls concordant for Brown's syndrome with reversed asymmetry are presented. This appears to be the first report of concordance for the presence of Brown's syndrome in twins. Embryological factors and a possible explanation for the etiology of this condition in the form as presented are discussed.
Phlyctenular keratoconjunctivitis.
There is growing evidence that a variety of corneal disorders may be expressions of altered immune mechanisms. Phlyctenular keratoconjunctivitis is probably such a condition. Typically described as arising from hypersensitivity to tuberculin protein, other antigens clearly may participate, particularly staphylococcus products. When corneal involvement occurs, it need not be confined to the peripheral cornea. The symptoms of the process may be disproportionate to obvious findings and so exaggerated as to suggest a psychiatric disorder. Resultant visual deficits, if the disease is corneal, progressive, unrecognized, and untreated may be profound. Representative examples of this disease are cited. Immune mechanisms are reviewed. The importance of recognizing the characteristic sign and symptom complex is stressed. Appropriate diagnostic studies and treatment regimens are presented.
Terrien's marginal corneal degeneration.
Terrien's disease is an uncommon (Terrien himself saw only three cases in thirty years of practice) corneal condition characterized by vascularization, opacification, lipid deposition, and thinning. With progression, large degrees of astigmatism occur and perforation is a threat. One-third of cases exhibit an inflammatory component. While typically described as a disease of middle to late age, these four cases indicate the full spectrum of clinical disease may be seen by an ophthalmologist who cares for children.
Role of the neural crest in anterior segment development and disease.
Certain eye and associated systemic developmental anomalies are apparently related by virture of a common neural crest origin. The development of the anterior segment is extremely complex and is dependent upon the presence or absence of certain local factors (including extracellular matrices and glycoproteins), inductors, receptors, and specific time sequencing. Understanding anterior segment anomalies and their systemic associations requires an understanding of neural crest proliferation and migration patterns; and they may be unified under the designation of neurocristopathies. Goldenhar's syndrome, not previously considered a neurocristopathy, may be considered one on the basis of the relationship between clinical findings and neural crest embryology.
Glycoconjugates, cellular differentiation, and congenital glaucoma.
Studies of congenital glaucoma have described and debated the disease process in cellular and structural terms, yet the functional aspects of the disease remain poorly understood. This paper presents an attempt to look at the disease from a different perspective: the role of glycoconjugates and their influence on morphogenesis of the corneoscleral angle. Extracellular and cell-surface complex carbohydrates and trabecular meshwork development were observed in normal C-57 BL/6J mice with light and electron microscopy. Lectin-stained fixed tissues were evaluated by fluorescein light microscopy and with computer-controlled scanning microspectrophotometry. The appearance and type of specific glycoconjugates was related to morphogenesis and differentiation, with specific reference to the development of the trabecular meshwork. Our results suggest that glycoconjugates are: (1) important in the morphogenesis of the corneoscleral angle, and (2) provide some of the required signals for the differentiation of the cells of the trabecular meshwork. These findings emphasize the possibility that a complex series of morphological and biological events in the normal development of the trabecular meshwork ultimately leads to a functionally competent trabecular meshwork, that is, capacitation.
Congenital glaucoma and retinal dysplasia.
The differential diagnosis of leukocoria (pseudoglioma) in the neonate includes multiple conditions, including malformations with retinal dysplasia as a component. Typically bilateral, retinal dysplasia is characteristically seen in microphthalmic eyes. Certain chromosomal defects have been described. The case reported herein presented in the first month of life with an enlarged eye, elevated intraocular pressure, prominent iris vasculature, and leukocoria. Family history was positive in one respect: this is the second child of a Viet Nam veteran exposed to Agent Orange. The first child, from a different mother, also had birth defects. Other than his left eye, the child is completely normal. Ultrasonography showed posterior vitreous opacities of indeterminate configuration. CT scan suggested a posterior intraocular mass. Histologically, the principal features were an anomalous, largely unformed corneoscleral angle, intraocular hemorrhage, and retinal dysplasia. Light microscopic studies were performed. The corneoscleral angle revealed an anteriorly inserted iris with an absence of trabecular meshwork and Schlemm's canal. This case is considered unique on the basis of the association of retinal dysplasia with congenital glaucoma and larger-than-normal eye. The significance of reported paternal exposure to Agent Orange in this instance is unknown.
Retinal vascular and optic nerve abnormalities in albinism.
Albinism is a condition in which the pigment melanin may not be synthesized from tyrosine. The fundus photographs of 24 eyes of 12 patients with the clinical diagnosis of either ocular or oculocutaneous albinism were reviewed. We observed two findings that to our knowledge have not been reported previously. Eighteen eyes of ten patients had prominent retinal vessels coursing through the putative macular area instead of arching around it. Large noncilioretinal vessels extended from the disc to the dysplastic "foveal zone" in eight eyes of five patients. Typical optic nerve hypoplasia (ONH) was seen in six eyes of four patients; features suggestive of ONH were present in an additional ten eyes of six patients. The cross-over (sharing) of clinical features between albinism and aniridia is striking and raises questions about pathophysiologic mechanisms.
An alternative hypothesis for iris maldevelopment (aniridia).
Two principal hypotheses for the pathogenesis of hypoplastic iris development ("aniridia") have been proposed: 1) the ectodermal theory, positing incomplete elaboration of the cup, resulting in an absence of framework for further development; and 2) the "mesodermal" theory, wherein inadequate migration or proliferation of mesenchymal elements is proposed. Two eyes of two patients with persistent "anterior leaf" iris strand remnants which traverse the pupillary space are reported. They are differentiated from the previously described persistent tunica vasculosa lentis. The presence of a persistent pupillary iris strand suggests portions of the iris may have formed and inappropriately regressed. Recent work in cell biology highlights the importance of remodeling and cell death in revealing ultimate phenotypic expression. This alternative hypothesis suggests that aniridia may be explained in part on the basis of excessive remodeling and cell death.
Collagen maturation defects in Ehlers-Danlos keratopathy.
Ehlers-Danlos syndrome is one of many inherited abnormalities of connective tissue, specifically collagen. A 16-year-old caucasian female with Type VI Ehlers-Danlos syndrome had five unusual corneal findings, four of which have not been reported in association with Ehlers-Danlos syndrome: micro-cornea (previously reported), cornea plana, keratoconus posticus, stromal haze at the level of Bowman's layer and a peripheral ring opacity suggestive of anterior embryotoxon. Type VI Ehlers-Danlos syndrome is associated with deficient activity of lysyl hydroxylase which ultimately is responsible for cross-linking collagen chains, the source of its tensile strength. Genetic regulation of procollagen formation is believed to be mediated by mRNA. Aggregation and maturation in the extracellular matrix is probably influenced and mediated by its evolving biochemical environment, particularly by complex carbohydrate moieties. An understanding of collagen maturation, and the pathophysiologic and biophysical consequences of abnormalities at this level of biochemical organization, permits more specific understanding of ocular dysmorphology and collagen diseases.