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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↗
PubMed1979

Vitreoretinal dissection instruments.

We developed and evaluated clinically a series of three vitreoretinal dissection instruments with a constant-diameter shaft and various tip designs including a 90-degree hooked tip, a 130-degree hooked tip, and a blunt-tip right-angle spatula. The instruments, manufactured from a titanium alloy, are lightweight and glare resistant. We have used these instruments interchangeably with other vitreous surgery instruments introduced through a 20-gauge sclerotomy. They facilitate delicate manipulations associated with separation of epiretinal membranes from the inner retinal surface.

Humans↗
PubMed1979

Surgical management of macular pucker after retinal reattachment surgery.

We used vitrectomy techniques to remove epiretinal membranes that caused reduced visual acuity in 13 consecutive eyes with macular pucker after otherwise successful retinal reattachment surgery. A technically successful result with visual improvement was achieved in each case. An iatrogenic retinal tear (successfully repaired) occurred in one eye, and recurrent retinal detachment requiring an additional operation occurred postoperatively in two eyes. Despite such risks, and that the best postoperative visual acuity achieved was 6/9 (20/30), the use of vitrectomy methods in removal of epiretinal membranes in selected cases of macular pucker can provide significant improvement in vision.

Adult↗
PubMed1979

Management of congenital cataracts.

The management of congenital cataracts at the Wilmer Institute is presented, with emphasis on the need for careful preoperative assessment. The indications and techniques for surgery in uncomplicated cataracts are discussed, and the advantages of using vitrectomy instruments in complicated congenital cataracts, such as those associated with persistent hyperplastic primary vitreous, are described.

Cataract↗
PubMed1979

Vitrectomy techniques in retinal reattachment surgery.

Vitreous surgery techniques are useful in the management of selected retinal detachments with an otherwise poor prognosis. Vitrectomy methods can be used to remove intraocular opacities; cut vitreous sheets causing vitreo-retinal traction and separate epiretinal membranes covering or distorting the retina; provide a fluid space to aid in creation of a scleral buckle or use of an intravitreal gas bubble; perform other intraocular procedures, including transvitreal treatment of retinal breaks, transvitreal removal of subretinal fluid, and intraocular fluid-gas exchange. These surgical capabilities can be combined with conventional retinal reattachment methods to treat selected types of retinal detachment. The surgical techniques, indications for surgery, and role of vitrectomy methods in the current management of retinal detachment are reviewed.

Cryosurgery↗
PubMed1979

Surgical management of epiretinal membranes.

Cellular membranes growing on the inner retinal surface occur in various ocular disorders, and modern methods of vitreous surgery permit removal of these membranes in selected cases. The surgical treatment of epiretinal membranes complicating proliferative retinopathies and rhegmatogenous retinal detachment is briefly described, and the results of such surgery in a series of thirteen consecutive eyes with macular pucker after otherwise successful surgery for rhegmatogenous retinal detachment are presented in detail. A technically successful result with visual improvement was achieved in each of the thirteen eyes. An iatrogenic retinal tear (successfully repaired) occurred in one eye, and recurrent retinal detachment requiring an additional operation occurred postoperatively in two eyes. Progression of lens opacities occurred postoperatively in four of six phakic eyes, and one eye later required cataract extraction. Despite such risks, and the fact that the best postoperative visual acuity achieved was 20/30, use of vitrectomy methods to remove epiretinal membranes can provide significant visual improvement in selected cases.

Adult↗
PubMed1979

Ultrastructure of epiretinal membranes causing macular pucker after retinal re-attachment surgery.

The ultrastructural features of the cellular components of surgically obtained preretinal membrane in twelve cases of macular pucker which followed retinal re-attachment surgery have been analysed. A mixture of different types of cells was observed. Definite (7) or probable (1) fibrous astrocytes were present in eight cases. Definite retinal pigment epithelium was the principal cell in only two cases, and four additional cases showed probable retinal pigment epithelium. Fibrocytes and macrophages were present in five cases and blood vessels in two. Nine of the twelve specimens included internal limiting membrane of the retina.

Aged↗
PubMed1979

Vitrectomy methods in anterior segment surgery.

We have used vitrectomy instrumentation and techniques to treat a variety of conditions affecting the anterior segment, including: 1) an occluded or inadequate pupillary space, 2) complications of vitreous in the anterior chamber, 3) epithelial ingrowth, 4) complicated lens surgery, and 5) total hyphema. The vitrectomy methods provided controlled excision of intraocular tissues under optimum visualization using a closed-eye system with normal intraocular pressure and the ability to use techniques such as intraocular diathermy. Our experience has been favorable in this series of 117 cases. Of these, 104 cases (89%) were anatomically successful, 70 eyes (60%) had a significant postoperative improvement in vision. The detailed results of vitrectomy surgery for anterior segment disorders are presented for each indication.

Adolescent↗
PubMed1979

Vitrectomy techniques in treatment of macular pucker following retinal reattachment surgery.

Vitrectomy techniques to remove epiretinal membranes causing macular pucker and reduced vision were used to treat 11 consecutive eyes with macular pucker after otherwise-successful retinal reattachment surgery. A technically successful result with visual improvement was achieved in each case. An iatrogenic retinal tear occurred in eye, and recurrent retinal detachment requiring an additional operation occurred postoperatively in 2 eyes. Despite such risks, and the fact that the best postoperative acuity achieved was 20/40, the use of vitrectomy methods in removal of epiretinal membranes in selected cases of macular pucker can provide significant improvement in vision.

Adult↗
PubMed1978

Vitrectomy for complications of diabetic retinopathy.

Pars plana vitrectomy was used to treat 134 consecutive eyes with complications resulting from proliferative diabetic retinopathy, including nonabsorbing vitreous hemorrhage, recent traction and rhegmatogenous retinal detachment, progressive fibrovascular proliferation, and early rubeosis iridis with recent vitreous hemorrhage. Vision improved after surgery in 65% of the eyes, was unchanged in 16%, and decreased after surgery in 19%. In 24% of the successful cases, vision of 20/50 or better was achieved. When all posterior cortical vitreous was removed, no preretinal fibrovascular growth occurred after surgery. Nonatrophic epiretinal fibrovascular membranes that were not removed usually underwent centripetal contraction after surgery, causing tangential traction on the adjacent retina. Rubeosis iridis was the most common postoperative complication in otherwise successful cases, and rubeosis underwent regression after scatter retinal photocoagulation in some eyes.

Adult↗
PubMed1978

Current surgical management of the vitreous wick syndrome.

We successfully treated three consecutive cases of the vitreous wick syndrome by combining repair of the fistula with closed vitrectomy to remove vitreous gel from the anterior chamber and from the internal aspect of the fistula. In two cases, the fistula seemed to be formed by the tract of an externally tied corneoscleral suture. In two cases the external opening of the fistula was large, and we covered it by a partial-thickness, anteriorly hinged scleral flap. One patient developed an epithelial ingrowth, which was successfully treated by transscleral and transcorneal cryotherapy combined with the use of an intraocular gas bubble to provide a thermal insulating effect to enhance the cryotherapy.

Aged↗
PubMed1978

Optic disk neovascularization in hemoglobin SC disease.

A 37-year-old black man had a clinically documented case of optic disk neovascularization associated with hemoglobin SC disease. Through medical evaluation, we ruled out other disorders associated with proliferative retinopathy. Extensive areas of retinal nonperfusion were associated with vasoproliferative retinopathy at the junction of the perfused and nonperfused retina; and a delicate network of neovascularization extended from the optic disk into the vitreous gel in one eye.

Adult↗
PubMed1978

Surgical management of epithelial ingrowth.

In ten consecutive cases of epithelial ingrowth operated on during the past 33 months, therapy included photocoagulation of the iris followed by excision of involved iris tissue and vitreous gel by means of instruments designed for vitreous surgery. Epithelium remaining on the posterior surface of the cornea, ciliary body, and in the anterior chamber was destroyed by controlled transcorneal and transscleral cryotherapy. An intraocular air bubble was used to provide an insulating effect and a more effective, controllable freeze. All patients except two had improved vision postoperatively, and four of the ten patients had postoperative visual acuity of 6/12 (20/40) or better.

Adult↗
PubMed1978

Vitrectomy techniques in the management of selected penetrating ocular injuries.

Closed vitrectomy techniques provide new capabilities to treat severe penetrating ocular injuries involving posterior segment structures. With these methods damaged iris tissue, lens, and vitreous can be removed and intraocular opacities can be cleared to identify and treat any retinal damage. Removal of damaged vitreous also prevents later cyclitic membrane formation and traction on the retina. The vitrectomy technique can be combined with additional methods to treat other conditions including nonmagnetic intraocular foreign bodies. We present the rationale and technique of vitrectomy together with the results of treatment in 51 consecutive cases of penetrating ocular trauma. Guidelines are offered for management of severe penetrating injuries.

Adolescent↗
PubMed1978

Anterior segment applications of vitrectomy techniques.

We have used vitrectomy instrumentation and techniques to treat a variety of conditions affecting the anterior segment, including: (1) Various conditions causing an occluded or inadequate pupillary space, (2) Complications of vitreous gel in the anterior chamber, (3) Growth of epithelium into the anterior chamber, (4) Selected indications for lens surgery, (5) Flat anterior chamber, (6) Total hyphaema. The vitrectomy methods provided improved capabilities, including controlled excision of intraocular tissues under optimum visualization using a closed-eye system with normal intraocular pressure and the ability to use accessory techniques such as intraocular diathermy. Although new difficulties are introduced by reliance on complex instrumentation and possible complications from excessive traction or use of large volumes of intraocular irrigating solution, our experience in using these techniques to treat selected anterior segment conditions has been, favourable.

Anterior Chamber↗
PubMed1978

Vitreous surgery techniques in penetrating ocular trauma.

Closed vitrectomy techniques provide new capabilities to treat severe penetrating ocular injuries involving posterior segment structures. With these methods, damaged iris tissue, lens, and vitreous can be removed and intraocular opacities can be cleared to identify and treat retinal damage. Removal of damaged vitreous also prevents later cyclitic membrane formation and traction on the retina. The vitrectomy technique can be combined with additional methods to treat other conditions including reactive nonmagnetic intraocular foreign bodies. We present the rationale and technique of vitrectomy, together with the results of treatment in 51 consecutive cases of penetrating ocular trauma. Guidelines are offered for management of severe penetrating injuries.

Adolescent↗