摘要:

The cave-dwellingTyphlotriton spelaeuslarvas live in daylight. The larvas undergo a metamorphosis when the thyroxin level (T3 and T4) increases. They leave aquatic life for terrestrial and subterranean aphotic life. The larval eyes are normal and show good vision response to tests. On the contrary, in the oldest larva and the adult, the eyes are small with poor vision or no vision at all. The lens can disappear but in any case the eyelids grow over the eye. The retinal degeneration takes place during and after metamorphosis. The admitted statement that “after metamorphosis…the developing lids close over the eye and invade the cornea” is not confirmed concerning the invasion, because it is now evident that the eyelids separate spatially from the residual cornea. Consequently, the fibroblasts of the eyelids are not able to invade the corneal stroma. In fact, the periocular tissues do not invade the cornea but invade the eyelids' tissues. We are able to confirm that the development of the larval eyes is complete and apparently normal. After metamorphosis, the eyes decrease in size. The cornea “sinks” with the eye into orbit tissues. The eyelids cover the eye and are themselves replaced by a supraocular skin. This fits the description of the human cryptophthalmia. We also demonstrate that even in the degenerate eye the residual cornea retains the main structure of a normal salamander cornea. The preservation of the endothelium and of the Descemet membrane is exceptional in blind cavedwelling vertebrates because in the other degenerate corneas the edema of the stroma depends on the spatial disjunction of the underepithelial stroma and the supraendothelial stroma. Perhaps, the very advanced development of the eye and the late start of the degenerative processes could explain the relative preservation of the cornea. Thus, the arguments put forward tend to prove that the thyroxinic metamorphosis sets off the growth and fusion of the eyelids but that the eye degeneration is related to hereditary processes.

ISSN:0277-3740    

出版商:OVID    

年代:1993

数据来源: OVID

摘要:

A 52-year-old man was first examined because of bilateral superficial punctate keratitis. Slit-lamp examination disclosed numerous intraepithelial minute opacities in both corneas. A corneal biopsy revealed intraepithelial rhomboidal or rectangular crystals that immunohistochemically stained only for IgG-kappa. Serum immunoelectrophoresis demonstrated an IgG-kappa monoclonal gammopathy. Over the ensuing 6 years, the clinical appearance of the crystals changed from small dot-like opacities to polychromatic crystals. At this time, bone marrow examination established the diagnosis of multiple myeloma. Ophthalmologists should be aware of this entity and carefully monitor these patients; the corneal lesions may be the initial manifestation of an asymptomatic monoclonal gammopathy preceding the development of multiple myeloma.

ISSN:0277-3740    

出版商:OVID    

年代:1993

数据来源: OVID

摘要:

Anterior corneal dystrophies involving Bowman's membrane and anterior stroma include several subtypes of uncertain etiology: the Reis-Bückler, Thiel-Behnke, Grayson-Wilbrandt, and “honeycomb” dystrophies. The clinical and pathologic features of these dystrophies overlap to such a degree that they may represent variations of the same entity. Typically, they all present symptoms beginning in childhood, have a dominant pattern of heredity, and manifest painful, recurrent corneal erosions. Some cases have also been interpreted as representing macular and granular dystrophy. In the present report, we describe a pedigree of affected patients whose corneal dystrophy shared many of the clinical and pathologic features of the Reis-Bücklers and allied subtypes but which differ from all in causing visual symptoms late in life and with minimal signs of recurrent erosion. Histopathology revealed a thickening of the anterior stroma by the addition of a partially disorganized and degenerating tissue in which collagen Type III (fetal or repair collagen) is intermixed with the normal (mature) Type I collagen in the entire stroma. This is accompanied by irregular swelling of the basal epithelial cells and hyperplasia of the basement membrane (collagen Type IV, laminin and fibronectin), suggesting an aberrant influence of the epithelium on collagen synthesis.

ISSN:0277-3740    

出版商:OVID    

年代:1993

数据来源: OVID