The components of the proliferative membranes in retinopathy of prematurity: an electron microscopic study.

Electron microscopic examination of proliferative membranes in retinopathy of prematurity (ROP) was performed in order to evaluate the components of the membranes. The proliferative membranes were obtained from nine patients with ROP stage 5 during pars plicata lensectomy, vitrectomy, and delamination of membrane. Fibrous astrocytes, myofibroblasts, lymphocytes, macrophages, and calcification were found respectively in two cases, and fibroblast-like cells were found in one case. Varying amounts of collagen tissues were found in eight cases and vascular tissues in four cases. Most of membranes were hypocellular and composed mainly of collagen matrix. It is considered that fibrous astrocytes, myofibroblasts, fibroblasts, and vascular structures are involved in the formation of proliferative membranes of ROP, and that later these cells degenerate and disappear, and that finally only collagen matrix remains in the membranes.

Myopia in premature infants at the age of 6 months.

The authors performed cycloplegic refractions in 180 eyes of 99 premature infants at the age of 6 months to evaluate the incidence and the degree of myopia according to the development and disease course of retinopathy of prematurity (ROP) and to investigate the effect of cryotherapy on the refractive error. The incidences of myopia were not different between premature infants without ROP and premature infants with spontaneously and totally regressed ROP (36.3%, 25.5%), and the degrees of myopia were low in both groups (-1.76 D, -2.25 D). In premature infants with totally regressed ROP after cryotherapy, the incidence of myopia was high (75.5%) but the degree of myopia was low (-3.03 D). In premature infants with cicatricial ROP, cryotreated or not, both the incidence and the degree of myopia were high (93.9%, -5.50 D). It is suggested that cryotherapy increases the incidence of myopia but the degree of myopia induced by cryotherapy is low.

PIP: Little is known about the incidence of myopia in premature infants with spontaneously regressed retinopathy of prematurity (ROP) without cicatricial changes or the effect of cryotherapy on refractive errors. The authors therefore report findings from cycloplegic refractions conducted in 180 eyes of 99 premature infants at age 6 months in order to evaluate the incidence and degree of myopia according to the development and disease course of ROP and to investigate the effect of cryotherapy on the refractive error. No differences were found between incidences of myopia in premature infants without ROP and premature infants with spontaneously and totally regressed ROP. The degree of myopia was low in both groups. A 75.5% incidence of myopia was observed in premature infants with totally regressed ROP after cryotherapy, but the degree of myopia was low. A 93.9% incidence of high degree myopia, however, was found among premature infants with cicatricial ROP regardless of whether or not they received cryotreatment. These findings suggest that cryotherapy increases the incidence of myopia, but the degree of myopia induced by this treatment is low.

Cellular components of proliferative vitreoretinal membranes.

To understand the pathogenesis of proliferative vitreoretinal membrane formation which occurs in proliferative vitreoretinopathy (PVR) and proliferative diabetic retinopathy (PDR), etc., accurate identification of the cellular components of the membrane is needed. This study was performed to identify cellular components of the membranes by means of immunohistochemical technique. 11 proliferative vitreoretinal membranes which were surgically obtained from 7 eyes with PVR and 4 eyes with PDR were stained with monoclonal antibodies against cytokeratin, glial fibrillary acidic protein (GFAP), or vimentin using immunoperoxidase technique (ABC method). In the PVR membranes, mean cell positivities for cytokeratin, GFAP and vimentin were 48%, 1% and 92%, respectively and in the PDR membranes, 0%, 5% and 93%, respectively. The above results suggest that retinal pigment epithelial cells and fibroblasts are major cellular components of PVR membranes, and that mesenchymal cells are major cellular components and glial cells are minor cellular components of PDR membranes.