Retinal dysplasia

Time-specific action of N-methyl-N-nitrosourea in the occurrence of retinal dysplasia and retinal degeneration in neonatal mice

The morphologic response of neonatal mouse retina to the alkylating agent N-methyl-N-nitrosourea (MNU) was examined at different periods of retinal development. A dose of 60 mg/kg N-methyl-N-nitrosourea was injected intraperitoneally to neonatal C57BL mice at 0, 3, 5, 8, 11, 14, 17, and 20 days of age and to C3H mice at 0 days of age, and the retinas were examined sequentially. In the C57BL mice, MNU evoked a time-dependent occurrence of retinal dysplasia and retinal degeneration. With MNU treatment at day 0 and day 3 (the stage of retinal cell proliferation), retinal dysplasia characterized by the progressive disorganization of neuroblasts, which led to the formation of rosettes, was found in the outer neuroblastic/nuclear layer above the normal pigment epithelial cells during days 8-20, but decreased at day 50. The rosettes were surrounded by photoreceptor segments and Müller cell processes, and by photoreceptor nuclei. The MNU response was related to retinal differentiation; following MNU treatment at day 5 or 8 (the stage of retinal cell differentiation) the cells were much less sensitive (i.e. no retinal response was found). However, with MNU treatment at days 11, 14, 17, and 20 (after cellular differentiation), retinal degeneration characterized by selective photoreceptor apoptosis was seen. These results suggest that there is a critical period for the time of MNU administration in the development of mouse retinal lesions. In C3H (rd/rd) mice, MNU treatment at day 0 resulted in retinal degeneration with only slight rosette formation at the peripheral retina.

The anterior segment anomalies in the Warburg syndrome. A study of new cases

The Warburg syndrome is a primary lethal neurodysplasia recently defined with autosomal recessive inheritance. The clinical diagnosis is based on the association of brain alterations with ocular defects, among which the anterior segment anomalies and the retinal dysplasia appear to be the most significant. The authors report a clinical and histopathological study on personal observations.

Autosomal recessive eye and brain anomalies: Warburg syndrome

Two siblings are reported who appear to have an autosomal recessive disorder of eye and central nervous system anomalies. The findings in fourteen previously described and similarly affected patients are summarized. Ocular anomalies include microphthalmos, megalocornea, the Peter anomaly, cataract, coloboma, persistent hyperplastic primary vitreous, and retinal detachment with retinal dysplasia. Central nervous system malformations include agyria-pachygyria, cerebellar dysplasia, encephalocele, Dandy-Walker cyst, and hydrocephalus. We suggest that this disorder be known as Warburg syndrome.

Retinal dysplasia

Retinal dysplasia is defined as an abnormal growth and differentiation of embryonic retina being more a secondary lesion rather than a disease. Clinically, the disorder may present itself in a surprisingly wide range of severity or of degree from retinal folds to vascularized masses in the vitreous cavity. The condition may appear monosymptomatically, involving only the eye, or as complex disorders with multisystemic anomalies. The histopathologic findings in this disorder recognize characteristic structural deviations of the retina and the pathogenesis seems to be related to the lack of the normal histogenesis of the pigment epithelium. Impaired genetic mechanisms seem to contribute to the etiology of some forms of retinal dysplasia.

Hydrocephalus combined with congenital cataract and microphthalmia

We describe a case of bilateral microphthalmia with bilateral congenital cataracts associated with hydrocephalus in a 9-month-old girl with consanguineous parents. The differential diagnosis included: (1) congenital rubella syndrome; (2) congenital toxoplasmosis; (3) chromosome alterations; and (4) metabolic disease. However, negative clinical, laboratory, and instrumental investigations excluded all of these hypotheses. We stress the usefulness of echography in establishing whether or not infection has occurred during intrauterine life.

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.