PubMed HealthSearch

Biomedical subjects

S J Ryan

Publications and source records attributed to S J Ryan.

At least 19 recordsLinked to original sources

Vitrectomy for perforating eye injuries from shotgun pellets.

Pars plana vitrectomy and scleral buckling were performed on 22 eyes of 19 patients for treatment of perforating eye injuries from shotgun pellets. We reviewed the intraoperative findings at the time of vitrectomy to determine what factors might influence final visual acuity. The presence of a total retinal detachment at vitrectomy portended a poor prognosis when compared with eyes without total retinal detachment, as only one of ten eyes with total retinal detachment obtained useful vision (P = .002). Preoperative separation of the posterior vitreous was associated with a favorable outcome when compared with the absence of posterior vitreous detachment (P = .035), as ten of 16 eyes with posterior vitreous detachment at the time of vitrectomy ultimately achieved functional vision. The locations of the exit wounds did not affect visual success in the overall series of patients. However, in the patients who achieved visual success, exit wounds outside the vascular arcades were more likely to be associated with final visual acuities of, or better than, 20/70 than were those within the arcades (P = .022). Other prognostic factors, such as the number of perforations and the use of cryotherapy, were also examined for their effects on final visual outcome. However, these factors did not appear to affect visual outcome statistically.

Adolescent

Maturation of newly-formed subretinal vessels.

The maturation process of newly-formed subretinal vessels was studied ultrastructurally. Primitive new vessels have thick endothelial cells with cytoplasm that contains many ribosomes and rough endoplasmic reticulum. Some immature endothelial cells show budding, and many of the intercellular junctions have small gaps. As the newly-formed vessels mature, the endothelial cells become attenuated and fenestrated, and their junctions become tight. Mature subretinal new vessels closely resemble those of the normal choriocapillaris.

Animals

Retinal pigment epithelium implantation in the rabbit: technique and morphology.

Dysfunction of the retinal pigment epithelium (RPE) is a major component of many degenerative disorders of the retina. We have developed a modified pars plana technique for subretinal implantation of homologous, cultured, carbon-loaded RPE cells in the rabbit. The natural history and morphologic behavior of the implanted RPE cells for up to 6 weeks after transplantation were observed in successful procedures.

Animals

Systemic antibiotic prophylaxis in penetrating ocular injuries. An experimental study.

Intraocular concentrations of systemically administered gentamicin and cefazolin in eyes after a standard penetrating ocular injury were measured to determine the effect of eye injury on ocular pharmacokinetics. Twenty pigmented rabbits were divided into two groups. A standard, 8-mm wound was made at the pars plana of one eye in each animal. Group 1 consisted of 10 rabbits that were treated with cefazolin (75 mg/kg), and Group 2 consisted of 10 rabbits that were given gentamicin (2 mg/kg). Fellow eyes, which sustained no trauma, served as control eyes. All groups received intravenous injections every 8 hours for 72 hours, beginning immediately after repair of the wound. After 72 hours, samples were obtained from the anterior chamber, vitreous cavity, and serum. Standardized bioassays for detection of gentamicin or cefazolin were performed. Significant concentrations of intravitreal cefazolin (9.6 micrograms/ml) and gentamicin (0.60 micrograms/ml) were found in the traumatized eyes in comparison to control eyes (P = 0.0001; P = 0.006). Cefazolin exhibited excellent penetration, achieving concentrations well above minimum inhibitory concentration values for most organisms. Gentamicin levels, however, were well below acceptable therapeutic levels. This study suggests that systemically administered cefazolin can achieve significant intravitreal penetration at minimum inhibitory concentrations after penetrating injury.

Animals

In vitro stimulation of retinal pigment epithelium proliferation by taurine.

Taurine is an amino acid that is essential for retinal integrity and function. Although it has been suggested that the ratio of melatonin to taurine in the interphotoreceptor matrix may regulate the phagocytosis of outer segments by retinal pigment epithelial (RPE) cells, the effect of taurine on the RPE has not been studied. Using cultured RPE cells, we found that in vitro taurine specifically stimulated proliferation of human and rabbit RPE, but had only minimal effect on cultured scleral fibroblasts. The RPE proliferation was due to more cells entering into S-phase and thus an increase in DNA synthesis, was not dependent upon cell density, and was most pronounced in the presence of a low concentration of fetal bovine serum.

Animals

Ultrastructures of the glial epiretinal membrane induced by activated macrophages.

A rabbit model of glial epiretinal membrane was established following the injection of activated macrophages into the vitreous. The membrane was composed entirely of cells with glial characteristics, ie, abundant intermediate filaments, microvilli, junctional complexes and basement membranes. The extracellular matrix of the mature membranes contained collagen fibrils of 10 to 15 and 20 to 25 nm in diameter. Fusiform densities were seen adjacent to the cell membrane and cells with indented nuclei were found in thick membranes. These observations demonstrate that glial cells in epiretinal membranes may synthesize collagen and possess myofibroblast-like properties.

Animals

Cultures of human retinal pigment epithelium. Modulation of extracellular matrix.

The extracellular matrix of retinal pigment epithelial (RPE) cells is an important component of the fibroelastic membranes formed in proliferative vitreoretinopathy (PVR). These membranes consist of cells intermingled with fibrillar proteins, such as elastin and collagen. Because RPE cells may be exposed to vitreous and serum-derived factors in conditions that lead to PVR, the effects of vitreous and serum on the deposition of fibrillar proteins by RPE cells were studied using radioactive labeling and indirect immunofluorescence techniques. The RPE cells, modulated by combined vitreous and serum into a fibrocytic-like appearance, deposited less fibroelastic proteins per cell. However, as a result of simultaneous cell proliferation, the total deposition of fibroelastic proteins per culture was increased. Indirect immunofluorescence studies suggest that it is type I collagen that is altered in the matrix of these modulated cell cultures. This information is important in pathologic conditions characterized by intraocular cell proliferation and fibroelastic membrane formation; these phenomena are seen in many vitreoproliferative disorders.

Cell Count

Prediction of visual acuity recovery in cystoid macular edema.

Three consecutive patients participated in a prospective evaluation of pseudophakic cystoid macular edema. The duration of the macular edema ranged from 6 to 8 months. On the initial visit, the best corrected acuity with spectacles was determined and a potential acuity meter reading was obtained; this test suggested potential for visual recovery in two of the three patients. Sub-tenon's injections of methylprednisolone acetate (20 mg) were administered along with topical 1% prednisolone acetate and 1% atropine. One month later, visual acuity was improved by more than 2 Snellen lines in all three of the patients. A visual acuity measurement with the potential acuity meter that is better than the best corrected acuity with spectacles may reflect the presence of intact, but dysfunctional photoreceptors that are capable of restoring visual acuity upon resolution of the edema.

Aged

Vision research in departments of ophthalmology. An Association of University Professors of Ophthalmology perspective.

A research committee of the Association of University Professors of Ophthalmology disseminated a survey questionnaire to determine the state of research in departments of ophthalmology across the United States. The questionnaire contained 71 questions that were designed to assess attitudes and trends within members' departments and to solicit suggestions from the membership. Of the 145 members and affiliates queried, 140 responded. While the results of the survey indicate significant diversity among departments, departmental chairpersons view research as a major priority in the goals of their departments, and they envision maintenance or expansion of research over the next decade. The survey results have been collated and serve now as the basis for this Association of University Professors position article.

Humans

Synthesis of extracellular matrix by macrophage-modulated retinal pigment epithelium.

In proliferative vitreoretinopathy, macrophages and retinal pigment epithelial cells are associated with microfibrillar matrix proteins in the vitreous cavity, but the contribution of this extracellular matrix to the pathophysiology is not known. We used radiolabeling techniques on cultured human retinal pigment epithelial cells to correlate the secretion of extracellular matrix proteins with macrophage-induced modulation of cell proliferation and morphologic features. Retinal pigment epithelial cells incubated in a macrophage-conditioned medium assumed fibrocytelike morphologic characteristics, grew faster, and exhibited a decreased cellular release of fibrillar and nonfibrillar matrix components. However, due to a simultaneous greater increase in cell numbers in these modulated cultures, the total production of fibrillar and nonfibrillar matrix components by the culture population was increased.

Cell Division

Methods, statistical features, and baseline results of a standardized, multicentered ophthalmologic surgical trial: the Silicone Study.

This article describes the trial design and baseline results for the Silicone Study, a multicenter, randomized surgical trial designed to compare the effectiveness of silicone fluid versus long-acting gas in the treatment of proliferative vitreoretinopathy (PVR). Design features include (1) standardization of the surgical protocol to reduce intersurgeon variability, (2) formulation of a PVR clinical classification system relevant to modern vitreoretinal surgery, and (3) creation of a photographic protocol to document PVR pathology. Statistical issues affecting the analysis of the outcome data include (1) the addition of a second group of patients with more severely diseased eyes after the trial began, (2) the change to a different long-acting gas during the course of the trial, and (3) recurrent retinal detachments that require reoperations with the randomized treatment, and, in some instances, a crossover from the randomized to the alternate treatment. Demographic and baseline ocular characteristics are presented for the two groups under study.

Adult

Subretinal endophotocoagulation. A new model of subretinal neovascularization in the rabbit.

The disciform response of age-related macular degeneration and other diseases is determined by the development of subretinal neovascularization (SRN). Experimental animal models of SRN based on disruption of Bruch's membrane have been studied extensively during the past decade. Argon laser photocoagulation-induced SRN in primates is one such model, but this is associated with extensive retinal damage. Because the injured retina could be angiogenic, and is not present in clinical SRN, this model might be more relevant if this factor could be eliminated. The current study was conducted with the primary aim of producing a rabbit model of SRN that minimizes retinal damage. Argon laser endophotocoagulation was applied beneath the retina of albino rabbits to achieve this goal. Although argon photocoagulation does not cause clinically apparent SRN (i.e., associated with leaking and pooling of fluorescein) in the rabbit, all laser lesions produced in the current study contained microscopic SRN. A rabbit SRN model would be highly desirable as a step toward other animal models, perhaps involving nonhuman primates, which might ultimately be clinically more relevant.

Animals

Pars plana vitrectomy for acute retinal detachment in penetrating ocular injuries.

We studied 41 eyes with acute retinal detachment after penetrating ocular trauma in a retrospective cohort analysis. Pars plana vitrectomy was performed in 28 eyes, while the remaining 13 eyes had only primary repair and closure of the wound. The two groups differed in the type of trauma (more gunshot wounds in the vitrectomy group and more blunt injuries in the nonvitrectomized group). Visual success (visual acuity of 5/200 or better) was observed in 10 (37%) of the eyes treated by vitrectomy compared with one (8%) of the eyes in the nonvitrectomy group. Anatomic success was achieved in 21 (75%) of the eyes in the vitrectomy group but in only one (8%) of those in the nonvitrectomy group. Enucleation or phthisis was observed in seven (54%) of the eyes in the nonvitrectomy group compared with only five (18%) in the vitrectomy group. Significant prognostic factors for anatomic outcome in the vitrectomy group were the location of the laceration and the presence of the lens.

Acute Disease

Ocular trauma in an urban population. Review of 1132 cases.

A retrospective survey was done of all ocular and adnexal trauma cases seen at a large metropolitan hospital during a 6-month period. By determining patient demographics, causes of the eye injuries, and extent of ocular damage, the authors hoped to delineate areas where preventive measures might decrease such trauma. Demographic and clinical data on 1132 patients were analyzed. Most patients were in the first three decades of life and were male. Blunt trauma was the most common type of injury. Assault was the most common cause and accounted for the highest number of serious injuries. Eye injuries associated with violence are difficult to prevent using conventional strategies that are usually effective in the home and workplace.

Adolescent

Management of traumatic rupture of the globe in aphakic patients.

We report the successful treatment of three cases of traumatic ruptures of the globe complicated by massive choroidal hemorrhage, uveal prolapse and retinal detachment. All three of the eyes were aphakic prior to injury and all patients were age 64 or older. The presenting visual acuity in all patients was light perception. The blunt injury in each case caused a wound dehiscence at the site of previous cataract extraction. All injuries were associated with uveal prolapse. Secondary surgical intervention was performed when the hemorrhagic choroidal detachments had decreased as demonstrated by echography in the suprachoroidal space, occurring at an average of 14 days after injury. The management consisted of surgical drainage of the choroidal hemorrhage combined with vitrectomy and silicone oil injection. Successful reattachment of the retina was achieved in all cases. Postoperative epiretinal membranes formed in two cases but all were anatomically successful at six months. Final visual acuities varied from 20/70 to 1/200, visual acuity being a function of secondary contusive damage to the retina and choroid. We believe that in eyes sustaining severe blunt injuries resulting in rupture of the globe complicated by massive choroidal hemorrhage and retinal detachment, properly timed external drainage of the choroidal hemorrhage combined with pars plana vitrectomy and silicone oil injection is a useful approach.

Aged

Effects of sodium iodate on experimental subretinal neovascularization in the primate.

We investigated the role of the retinal pigment epithelium (RPE) in the development of subretinal neovascularization (SRN) induced by bilateral laser photocoagulation of the retinas in monkeys. RPE function was affected by a unilateral carotid injection of sodium iodate, a selective RPE toxin, before laser photocoagulation. This caused severe RPE damage in the ipsilateral eye, but did not affect the contralateral eye. After laser photocoagulation no SRN was demonstrable clinically or histopathologically in the ipsilateral eye; in contrast, active SRN showing extensive fluorescein leakage was found in the contralateral eye. These results suggest that RPE may play a role in the development of laser-induced SRN.

Animals