Biomedical subjects

R G Michels

Publications and source records attributed to R G Michels.

At least 19 recordsLinked to original sources

PubMed1992

Transforming growth factor-beta 2 for the treatment of full-thickness macular holes. A prospective randomized study.

BACKGROUND: Full-thickness macular holes generally cause a significant reduction in visual acuity, due in part to a rim of surrounding neurosensory retinal detachment and retinal thickening. Recent studies have suggested that flattening of this narrow rim of neurosensory detachment can result in improved visual acuity. However, the ability to flatten the neurosensory detachment is limited using current surgical techniques. METHODS: Transforming growth factor-beta 2 (TGF-beta 2) is a recently discovered potent stimulator of wound healing. The authors, therefore, performed a prospective randomized study of 60 patients to determine if the local application of TGF-beta 2 to the edge of the macular hole can reproducibly induce flattening of the surrounding neurosensory detachment. The results of a study designed to determine the effect of a pars plana vitrectomy, fluid-gas exchange, and intravitreal instillation of TGF-beta 2 in eyes with a full-thickness macular hole and reduced visual acuity are reported. RESULTS: After treatment, visual acuity improved 2 lines or more in 5 of 11 eyes treated with 70 ng, in 4 of 12 eyes treated with 330 ng, and in 10 of 11 eyes treated with 1330 ng of TGF-beta 2. In some eyes, hyaluronic acid was added. In these cases, visual acuity improved 2 lines or more in 0 of 9 eyes treated with 70 ng TGF-beta 2, in 2 of 8 eyes treated with 330 ng, and in 4 of 9 eyes treated with 1330 ng. CONCLUSION: Logistic regression analysis demonstrated a statistically significant beneficial effect of TGF-beta 2 on visual improvement (P = 0.003).

Adolescent↗

PubMed1992

Clinicopathologic study of idiopathic macular pucker in children and young adults.

Clinically significant idiopathic macular pucker was observed in 11 patients aged 30 years or younger. In these patients, the tissue was well defined and fibrous in appearance, in contrast to the thin, cellophane appearance that is typical of macular pucker in elderly patients. Vitrectomy and epiretinal membrane peeling were performed in each case. Visual acuity improved after surgery in seven cases and worsened in one case, and follow-up data was not obtained in three cases. Recurrent membranes were noted in four cases, two of which detached spontaneously. Ultrastructural studies were performed on the removed specimens in each case. Myofibroblasts, myoblastic differentiation of retinal pigment epithelial cells and fibrous astrocytes, and new collagen formation were more common than in idiopathic macular pucker in older patients. The clinical and ultrastructural features of juvenile macular pucker reflect more rapidly changing, contractile tissue compared with the usually more quiescent features in series involving older patients.

Adolescent↗

PubMed1991

Nuclear sclerotic cataract after vitrectomy for idiopathic epiretinal membranes causing macular pucker.

We evaluated the occurrence or progression of nuclear sclerosis of the crystalline lens in 100 eyes after vitrectomy for removal of idiopathic epiretinal membranes causing macular pucker. The follow-up period ranged from six to 99 months (average, 29 months). Visually significant nuclear sclerosis was present preoperatively in three of the operated on eyes and four of the fellow eyes. The rate of occurrence or progression of visually significant nuclear sclerosis was far greater in the operated on eyes (P less than .0001). Of 100 patients, 80 operated on eyes and 24 fellow eyes had visually significant nuclear sclerosis or had undergone previous cataract extraction at the conclusion of the study. Different concentrations of glucose in the intraocular irrigating solution did not affect occurrence of later nuclear sclerosis. Patients older than 50 years of age had a far greater incidence of later nuclear sclerosis than patients younger than 50 years of age (P = .0003). Nuclear sclerosis may be caused by altered lens metabolism after removal of part of the vitreous gel, since nuclear sclerosis also occurs in other conditions associated with vitreous liquefaction.

Adolescent↗

PubMed1991

Extracellular matrix of newly forming vessels--an immunohistochemical study.

During wound healing, embryological development, and solid tumor growth, the established vasculature gives rise to large numbers of new blood vessels. This neovascular response occurs at the level of the capillary bed, where endothelial cells divide rapidly, locally remodel the surrounding stroma, and migrate away from existing vessels to form capillary sprouts. In order to examine the environment of these newly forming vessels, actively growing blood vessels in neovascularized rabbit and guinea pig corneas were examined immunohistochemically using antibodies against laminin, type IV collagen, heparan sulfate proteoglycans, entactin, and factor VIII-related antigen. Sequential serial 5-microns sections taken from the unfixed frozen corneas in a plane perpendicular to the direction of vessel growth were stained with these antibodies. It was possible to follow well-defined lumenized vessels out through sequential sections to the point where they became single factor VII-R positive cells in the region of the capillary sprout. Examination of these stained sections has shown the presence of four important basement membrane components--laminin, type IV collagen, heparan sulfate proteoglycan, and entactin--associated with actively migrating and invading capillary sprouts. These results suggest that the extracellular matrix of the actively invading capillary sprouts does not differ qualitatively from that of the established vasculature.

Animals↗

PubMed1991

Perfluoro-octane in the treatment of giant retinal tears with proliferative vitreoretinopathy.

Giant retinal tears complicated by proliferative vitreoretinopathy (PVR) pose one of the more complex problems in vitreoretinal surgery. The authors developed a technique using perfluoro-octane, a temporary vitreous substitute that is heavier than water, combined with vitrectomy, scleral buckling, fluid-gas exchange, and direct manipulation of the retina to treat these cases. Ten eyes with giant retinal tears and grade D-1 PVR or worse were treated. In all eyes, the retina was successfully reattached at the end of surgery. Nine of the ten retinas remained attached after 6 months of follow-up. Five eyes required a total of six reoperations for epiretinal membrane formation without retinal detachment. The one eye in which the retina did not remain reattached developed severe recurrent PVR and iris neovascularization. Visual acuity improved in 8 of 10 eyes. Final visual acuity was 20/400 or better in 8 of 10 eyes, and 20/80 or better in 4 eyes.

Adult↗

PubMed1991

Long-term survival rate after vitreous surgery for complications of diabetic retinopathy.

The survival rate after vitreous surgery for complications of diabetic retinopathy was studied in 552 consecutive patients who underwent operations between 1979 and 1984. The 5-year postoperative survival rate was 74.7%. Factors associated with a lower survival rate included older age, older age at diagnosis of diabetes, history of renal disease, and a longer duration of diabetes. Factors unrelated to survival rate included insulin treatment, sex, and anatomic and visual outcome. Improved management of systemic diabetic complications has improved survival rates, a finding reflected in the relatively high rate of long-term survival after diabetic vitrectomy.

Adolescent↗

PubMed1991

Lens and peripheral retinal relationships during vitrectomy.

Relationships between the posterior surface of the crystalline lens and instruments introduced into the vitreous cavity through pars plana incisions were evaluated in ten eyes from cadavers. Instruments were introduced 3.0 mm, 3.5 mm, and 4.0 mm posterior to the anterior part of the limbus. The distance between an instrument oriented toward the center of the vitreous cavity and the peripheral edge of the lens in that meridian was 1.6 mm when the sclerotomy was 3.0 mm from the limbus and 2.8 mm when the sclerotomy was 4.0 mm from the limbus. The arc length from the sclerotomy where the instrument was introduced to the most distal meridian of the ora serrata that could be reached without touching the lens ranged from 2.8 to 3.8 clock hours as the distance between the sclerotomy and the limbus increased from 3.0 mm to 4.0 mm. The distance between the ora serrata and the most peripherally accessible point on the retina in the meridian 180 degrees from the sclerotomy decreased from 6.0 mm to 3.1 mm as the distance between the limbus and the sclerotomy increased from 3.0 mm to 4.0 mm.

Humans↗

PubMed1991

Dissection of epiciliary tissue to treat chronic hypotony after surgery for retinal detachment with proliferative vitreoretinopathy.

Surgery was performed on nine eyes of nine consecutive patients with chronic postoperative hypotony after prior vitreous surgery for retinal detachment and proliferative vitreoretinopathy. The operation included lysis of adhesions between the iris and the ciliary processes and removal of lens remnants and other fibrocellular tissue covering and/or causing traction on the pars plicata. The preoperative intraocular pressure was less than or equal to 5 mm Hg in all eyes, and the final postoperative intraocular pressure was 8 to 20 mm Hg in five eyes, 6 mm Hg in one eye, 4 mm Hg in one eye, and 0 mm Hg in two eyes. Minimum postoperative follow-up was 7 months and average follow-up was 10 months. This form of surgery to uncover and minimize traction on the ciliary body substantially increased the intraocular pressure in most of the treated cases and suggests that iridociliary adhesions and tissue proliferation covering and/or causing traction on the ciliary processes account for chronic postoperative hypotony in some cases after extensive surgery for proliferative vitreoretinopathy.

Aged↗

PubMed1990

Epiretinal membrane contracture associated with macular prolapse.

We treated two patients with annular epiretinal membranes that produced unusual macular morphologic characteristics. Contracture of the membranes caused herniation of macular tissue through a hole in the center of the membrane. The membranes were removed surgically, and ultrastructural analysis disclosed cells with properties resembling myofibroblasts and apparent new vitreous collagen. Contracture of the cellular components probably produced tangential traction on the retina, which caused prolapse of the retinal tissue through a central defect in the membrane.

Child↗

PubMed1990

Iatrogenic retinal breaks complicating pars plana vitrectomy.

To determine the current incidence and outcome of iatrogenic retinal breaks occurring during pars plana vitrectomy, the authors reviewed 404 consecutive operations done on eyes without preexisting retinal breaks. Thirteen eyes had 14 iatrogenic peripheral retinal breaks. Three other eyes had both peripheral breaks and posterior breaks. Twenty-five eyes had 43 posterior breaks. The incidence of peripheral breaks was 4% and of posterior breaks was 6%. Patients with proliferative diabetic retinopathy had a higher incidence of iatrogenic retinal breaks than those with other diagnoses. Peripheral breaks occurred most commonly just posterior to the site of insertion of the vitrectomy probe. Although six eyes required reoperation, 33 of 38 eyes had a successful anatomic outcome.

Cohort Studies↗

PubMed1990

Recovery of intraocular Toxocara canis by pars plana vitrectomy.

Pars plana vitrectomy has been used in cases of ocular toxocariasis to remove vitreous opacities due to chronic inflammation and to relieve vitreo-retinal traction causing macular distortion and retinal detachment. To date, the diagnosis of intraocular Toxocara infection in vitrectomy cases has been presumptive, based on characteristic clinical findings, the presence of eosinophils, and corroborative immunodiagnostic tests. The authors report a case in which a vitrectomy for vitreopapillary traction recovered an intact Toxocara canis organism.

Adolescent↗

PubMed1990

Retinal detachment in highly myopic eyes due to macular holes and epiretinal traction.

We operated on four highly myopic eyes with recurrent retinal detachment due to macular holes. A thin layer of epiretinal tissue was present over the posterior retina in each eye, probably causing tangential traction on the retina and accounting for the recurrent detachment. Biopsy of the tissue from one case showed mainly acellular material resembling cortical vitreous. Recognizing this clinical condition may permit successful treatment of certain cases with recurrent retinal detachment in highly myopic eyes with macular holes.

Adult↗

PubMed1990

Morphology, pathology, and surgery of idiopathic vitreoretinal macular disorders. A review.

Macular pucker, the vitreomacular traction syndrome, and impending macular hole are three idiopathic macular disorders sometimes treated by vitreous surgery. Each condition has distinctive clinical features, pathogenic mechanisms, vitreoretinal anatomy, surgical findings, results, and complications. The clinical and pathologic features of these three conditions are compared based on a series of: (1) 101 idiopathic macular pucker cases for which clinicopathologic correlation with transmission electron microscopy (CPC-EM) was available, (2) 24 cases of the vitreomacular traction syndrome (7 patients with CPC-EM), and (3) 43 cases of impending macular hole (7 patients with CPC-EM). All cases of macular pucker, 16 cases of vitreomacular traction syndrome, and 15 cases of impending macular hole have been reported. The median visual acuity for patients with epiretinal membrane and vitreomacular traction syndrome improved from 20/200 preoperatively to 20/70 and 20/50 postoperatively. Macular holes occurred postoperatively in 11 of 43 patients with impending macular hole. The three conditions must be differentiated clinically so that proper recommendations regarding prognosis and possible surgical management can be made.

Eye Diseases↗

PubMed1990

Evolving concepts in the management of posterior segment penetrating ocular injuries.

Advances in understanding the pathobiology of secondary complications after posterior segment penetrating ocular injuries along with progress in instrumentation and surgical techniques have provided a powerful means to salvage certain eyes that would otherwise be lost. Further progress will probably include the use of pharmacologic agents that interfere with fibrocellular proliferation, as well as better delineation of the methods and timing of surgery.

Animals↗

PubMed1990

Miosis during vitreoretinal surgery.

Maintenance of wide pupillary dilation during vitreoretinal surgery can be important in successful completion of the operation. This study identified factors associated with intraoperative miosis. Also, flurbiprofen, a topically applied nonsteroidal anti-inflammatory agent, was evaluated for its efficacy in preventing intraoperative miosis in a prospective, randomized study of 99 consecutive patients. Factors associated with intraoperative miosis included duration of surgery greater than 90 minutes, preoperative afferent pupillary defect, and recent previous surgery. Preoperative treatment with flurbiprofen did not decrease the risk of intraoperative miosis.

Chi-Square Distribution↗

PubMed1990

Goldmann-Favre maculopathy.

A healthy 17-year-old girl presented with typical symptoms and physical features of Goldmann-Favre vitreoretinal degeneration. She had reduced visual acuity in both eyes and night blindness. Her parents were first cousins. Striking fundus features included typical maculopathy with a radiating stellate pattern surrounded by tiny vacuole-like pockets of retinoschisis throughout the posterior pole within the temporal vascular arcades. The fundus features were quite typical and permitted a firm diagnosis when combined with the other features of night blindness, gender, and electroretinogram (ERG) abnormalities.

Adolescent↗

PubMed1990

Surgical treatment of postoperative dilated, nonreactive pupil in eyes after combined pars plana lensectomy and vitrectomy.

Synechiae between the iris and tissue posterior to the iris can cause a markedly dilated, nonreactive pupil that is cosmetically undesirable after combined pars plana lensectomy and vitrectomy for complicated forms of retinal detachment. The authors have used a combined limbal and pars plana approach to lyse the posterior synechiae, resulting in partial pupillary constriction. The surgical technique is described, and clinical results are illustrated.

Adolescent↗

PubMed1990

Clinicopathologic correlation of recurrent epiretinal membranes after previous surgical removal.

Recurrent epiretinal membranes (ERMs) causing macular pucker developed after surgical removal in seven eyes and were subsequently removed. A specimen was available for electron microscopic study from four of the seven primary operations and all seven of the repeat operations. The diagnostic associations for the primary cases included retinal holes or tears (four eyes), trauma, inflammation (one eye each). In one eye the membrane was idiopathic. The primary and recurrent ERM specimens contained similar cell types and structural characteristics but were not identical. No one cell type predominated in either primary or recurrent ERM. Compared with studies of idiopathic ERMs, myofibroblasts were present with increased frequency in recurrent membranes. Fibrocytes, fibrous astrocytes, and retinal pigment epithelial cells were also present in most specimens. Other features of both the primary and recurrent ERM specimens included the presence of cells with myoblastic differentiation, fragments of internal limiting membrane, new collagen, and nerve fiber elements.

Adult↗