Vitreoretinal findings similar to retinopathy of prematurity in infants with compound heterozygous protein S deficiency.

OBJECTIVE: To present previously undescribed vitreoretinal findings similar to severe retinopathy of prematurity (ROP) in two siblings (daughter and son) with a thrombophilic disorder, compound heterozygous protein S (PS) deficiency. DESIGN: Family genotype study and literature review. PARTICIPANTS: Two unrelated heterozygous PS-deficient parents and their two children with compound heterozygous PS deficiency were studied. The gestational age and birth weight of the daughter were 40 weeks and 3200 g, respectively, and those of the son were 34 weeks and 2150 g, respectively. Three other neonates with homozygous or compound heterozygous PS deficiency and ophthalmologic findings were identified in the literature. INTERVENTION: The daughter underwent lensectomy-vitrectomy at 48 weeks adjusted age bilaterally. The son underwent therapy developed for severe ROP: laser therapy of the peripheral avascular retina at 39 weeks adjusted age, and bilateral lensectomy-vitrectomy with membrane peel of intravitreous proliferation from the optic disc at 42 weeks adjusted age. MAIN OUTCOME MEASURES: The main clinical outcome measures were retinal appearance and functional vision. Genotypes of the family members were determined. RESULTS: One of the four eyes retained functional vision. A normal-appearing posterior retina, normal scotopic and photopic flash electroretinograms, and a normal flash visual-evoked response were documented from the left eye of the son at 62 weeks adjusted age. The other three eyes had inoperable retinal detachments and no functional vision. The mother had type I PS deficiency and the father had type II PS deficiency. Compound heterozygous PS deficiency was confirmed in both children. CONCLUSION: In both children, normal vasculogenesis was interrupted. At 39 weeks adjusted age, the retinal examination of the son revealed extraretinal fibrovascular proliferation at the optic disc (reactivation of the hyaloid system) and in the peripheral retina (interruption of inner retinal vascularization). Patients with homozygous or compound heterozygous PS deficiency may present as infants with severe ROP. The authors' experience suggests that appropriately timed surgical procedures, which are efficacious for ROP, can preserve vision in infants with thrombophilic disorders.

The statistical inevitability of stability-diversity relationships in community ecology.

In this article, we explain an often overlooked process that may significantly contribute to positive correlations between measures of species diversity and community stability. Empirical studies showing positive stability-diversity relationships have, for the most part, used a single class of stability (or, more accurately, instability) measures: the temporal variation in aggregate community properties such as biomass or productivity. We show that for these measures, stability will essentially always rise with species diversity because of the statistical averaging of the fluctuations in species' abundances. This simple probabilistic process will operate in the absence of any strong species interactions, although its strength is driven by the relative abundances of species, as well as by the existence of positive or negative correlations in the fluctuations of species. To explore the possible importance of this effect in real communities, we fit a simple simulation model to Tilman's grassland community. Our results indicate that statistical averaging might play a substantial role in explaining stability-diversity correlations for this and other systems. Models of statistical averaging can serve as a useful baseline for predictions of community stability, to which the influences of both negative and positive species interactions may then be added and tested.

Long-term form identification vision after early, closed, lensectomy-vitrectomy for stage 5 retinopathy of prematurity.

PURPOSE: Form identification vision after early, closed, lensectomy-vitrectomy for retinopathy of prematurity (ROP) stage 5 open funnel retinal detachment is reported from a database that included 45 eyes of 27 infants. The focus of this report is the verbal responses at a mean age of 7.0 years for nine nonamblyopic (preferred) eyes of nine preterm infants with minimal developmental delay (good central nervous system function). METHODS: All 45 eyes underwent initial cryotherapy for threshold ROP to the avascular retina to decrease the angiogenic stimulus (mean postconceptual age = 34.8 weeks) and subsequently underwent multiple cryotherapy sessions to the avascular retina and shunt with scleral buckling to decrease retinal traction (mean postconceptual age = 38.0 weeks). When tractional retinal detachment occurred with an open funnel, each eye underwent an early, closed, lensectomy-vitrectomy (mean postconceptual age = 45.7 weeks). The 34 eyes with a successful anatomic result were fitted with contact lenses as soon as possible after surgery. RESULTS: The nine nonamblyopic eyes of nine preterm infants with minimal developmental delay had the following visual acuities using Allen figures or Snellen test types: one eye 20/80, one eye 20/200, two eyes 20/400, three eyes 20/800, and two eyes 20/ 1600. CONCLUSION: These nine eyes support the thesis that form identification vision can be obtained by early vitrectomy for ROP stage 5 open funnel retinal detachments.

Primary ocular malignant lymphoma associated with the acquired immune deficiency syndrome.

A 42-year-old man who was human immunodeficiency virus (HIV)-positive complained of floaters in his right eye, which had existed for 1 week, followed by loss of central vision. Results of ophthalmoscopic examination disclosed confluent yellowish-white retinochoroidal infiltrates with perivascular sheathing, which were more prominent superiorly in the right eye. Approximately 10 small, white, intraretinal and choroidal lesions were observed in the nasal periphery of the left eye. Results of cytologic examination of the vitreous of the right eye showed neoplastic cells characteristic of large cell type malignant lymphoma. Shortly thereafter, cytologic examination of the cerebrospinal fluid also showed large cell malignant lymphoma. Magnetic resonance imaging (MRI) showed a mass involving the left cerebellar hemisphere. After bilateral whole-eye radiation therapy, there was complete resolution of the lymphomatous retinochoroidal infiltrates in both eyes. The ophthalmologic and neurologic manifestations of acquired immune deficiency syndrome (AIDS) are discussed. The authors believe this is the first report of ocular malignant lymphoma occurring in a patient with AIDS.

Pigmented free-floating vitreous cysts in two young adults. Electron microscopic observations.

Pigmented free-floating vitreous cysts were observed in two young adults. In both patients, the cyst was in the visual axis; however, the size and extent of pigmentation of the cyst wall compromised the visual acuity only in case 1. In this case, the vitreous cyst was aspirated through the pars plana and studied by light and electron microscopy. Histopathologically, the cyst was lined by a heavily pigmented layer of cuboidal cells intermixed with sheets of nonpigmented cells forming papillae. Ultrastructurally, the pigmented cells contained predominantly large, mature melanosomes (0.9-2.2 micron). Scattered immature melanosomes with a scarcity of mitochondria and other cytoplasmic organelles were present. Additionally, the cells were invested by a thin polarized basement membrane and displayed apical microvilli. Numerous microvillous processes were noted under the plasmalemmae and between adjacent cells. The results of the light and ultrastructural studies provide support for the hypothesis that the cyst in case 1 originated from the pigment epithelium. The possibility of a traumatic etiology is proposed for these pigmented vitreous cysts. If significant visual impairment is present, surgical removal of the cyst through a pars plana approach can be safely performed as in our case 1.

Retinal detachment following late posterior capsulotomy.

When we compared the incidence of retinal detachment in 27 eyes after extracapsular cataract surgery and late posterior capsulotomy with the incidence of general aphakic detachment, we found no relationship between the onset of retinal detachment and the numbers, types, or locations of breaks. The interval between cataract extraction and discission had a significant effect on recovery of visual acuity. Final visual acuities of 20/400 or better were attained in 22 of 23 eyes in which discission followed cataract extraction by one year or more but in only one of four eyes in which the procedures were separated by less than one year. Delaying discission for more than 12 months may reduce the extent of retinal detachment and produce the best functional results. Detachments that occurred less than one year after discission were more extensive but achieved better functional results than those that occurred later.

Visual acuity after surgery for retinal detachment with macular involvement.

The records for a group of 2,054 patients who had undergone surgery fur rhegmatogenous retinal detachment with macular involvement were analyzed to ascertain the relative influence of the following five specific factors on postoperative visual acuity: (1) patient age, (2) degree of preoperative macular elevation, (3) duration of preoperative macular detachment, (4) extent of retinal detachment, and (5) drainage of subretinal fluid. Increasing patient age, increasing preoperative macular elevation, increasing duration of macular detachment, and increasing extent of retinal detachment were all found to be associated in general with decreasing postoperative visual acuity. Drainage, or nondrainage, or subretinal fluid appeared to be unassociated with postoperative visual acuity.