PubMed Health⌕ Search

Biomedical subjects

H M Freeman

Publications and source records attributed to H M Freeman.

At least 19 recordsLinked to original sources
PubMed1991

An updated classification of retinal detachment with proliferative vitreoretinopathy.

The Retinal Society classification on proliferative vitreoretinopathy of 1983 has been updated to accommodate major progress in understanding of this disease. There are three grades describing increasing severity of the disease. Posterior and anterior location of the proliferations have been emphasized. A more detailed description of posterior and anterior contractions has been made possible by adding contraction types such as focal, diffuse, subretinal, circumferential contraction, and anterior displacement. The extent of the abnormality has been detailed by using clock hours instead of quadrants.

Eye Diseases↗
PubMed1988

Anterior proliferative vitreoretinopathy. Clinicopathologic, light microscopic, and ultrastructural findings.

Proliferative vitreoretinopathy (PVR) involving the posterior and equatorial retina is an established clinicopathologic entity. Clinically, a similar process, anterior PVR (APVR), results in anterior dragging of the peripheral retina by membranes which connect to the ciliary body or iris and cause circumferentially and radially fixed retinal folds. The pathology of APVR, however, has not been reported. The authors describe pathologic findings in 28 cases of APVR and ultrastructural pathologic findings in 6 surgical APVR specimens. Anterior PVR was frequently associated with retinal detachment (RD) repair (96%) and trauma (38%). Residual vitreous at the vitreous base virtually always provided a scaffold for membranes containing proliferating cells and deposited extracellular matrix. Major components of APVR membranes were fibrovascular tissue (71%), pigment epithelial cells (43%), fibrous and corneal stromal ingrowth (32%), and glial proliferation (18%). Because of its anterior location, APVR membranes also incorporated ciliary epithelium and corneal endothelium. Contraction of APVR membranes caused anterior retinal displacement and detachment in anatomic configurations corresponding to narrow and wide peripheral troughs. The authors' findings indicate that APVR is a distinctive clinicopathologic entity which may complicate rhegmatogenous RD and its repair.

Adult↗
PubMed1979

A new lens for closed pars plana vitrectomy.

A new prismatic type of lens enables a more peripheral view of the vitreous cavity. The surface in contact with the cornea is concave. The opposite surface is plano but inclined to produce a prismatic effect of 15 degrees or 25 degrees. A cannula attached to the lens provides corneal irrigation. Although this lens was originally designed for vitrectomy use, it is also useful for diagnostic biomicroscopy of the vitreous and fundus in the office.

Humans↗
PubMed1979

Vitrectomy in penetrating ocular trauma: an experimental study using rabbits.

To study the value and the proper timing of vitrectomy in cases of ocular trauma involving the posterior segment, 24 rabbit eyes were traumatized by introducing a steel foreign body and autogenous blood into the vitreous. Twelve eyes underwent vitrectomy, 6 in the first week after trauma ("early") and 6 in the fourth week ("late"). The other 12 eyes, which underwent removal of the foreign body but not vitrectomy, served as controls. Traction retinal detachment did not develop in the 6 early-vitrectomy eyes, but it did occur before vitrectomy in 4 of the 6 eyes of the late-vitrectomy group and in 6 of the 12 control eyes. Iatrogenic cataract and retinal breaks were twice as frequent in the late as in the early group. The data seem to favor early vitrectomy in eyes with posterior-segment trauma. However, in routine clinical practice we advise prompt primary repair and exploration to evaluate the extent of posterior-segment damage, and vitrectomy within 14 days after injury.

Animals↗
PubMed1978

Retinal detachment due to ocular penetration. I. Clinical characteristics and surgical results.

The records of 74 patients--young and almost exclusively males--with retinal detachment due to ocular penetration were reviewed to study the characteristics and surgical results of this type of traumatic retinal detachment. There was a high incidence of industrial and domestic accidents. The incidence and degree of myopia were significantly lower than in nontraumatic cases of retinal detachment. The time interval between the injury and the detection of the retinal detachment was variable. Many of the eyes with longer latent intervals had classic signs of traumatic retinal detachment. The most common type of retinal break was a dialysis in the oral zone at the posterior vitreous base border. The most common cause of these retinal breaks was severe traction from contracting vitreous bands and membranes that followed the loss of vitreous gel from the eye. Surgical results were relatively poor; recurrence was common because of progressive vitreous pathology. Postoperative traction on the vitreous base by the continued shrinkage of vitreous membranes was noted in 50% of the eyes that contained such membranes preoperatively.

Adolescent↗
PubMed1978

Intravitreous silicone balloon: an experimental study.

A specially designed silicone balloon, expanded in vivo with normal saline, was tested for possible use as a retinal tamponade in desperate cases of rhegmatogenous retinal detachment. In six pigmented rabbits there were extensive postoperative complications, but in eight owl monkeys results were noticeably better. When the seam of the balloon was in contact with the retina there were adverse effects; seamless areas of the balloon did not appear to disturb the retina. Histopathologic studies indicated that excessive expansion of the balloon can cause significant damage, but that carefully controlled expansion can probably minimize complications. The presence of the balloon appears to alter electroretinographic response, but without necessarily causing histopathologic changes. Balloons of this type have been used in treatment of a small number of otherwise inoperable cases of retinal detachment with promising results.

Animals↗
PubMed1978

Fellow eyes of giant retinal breaks.

INCIDENCE OF RETINAL BREAKS AND DETACHMENT IN FELLOW EYES. The fellow eyes of 226 giant retinal breaks were followed in order to determine the incidence and natural course of chorioretinal and vitreous pathology. During the period of observation which ranged from 18 months to 16 years, the incidence of retinal breaks and retinal detachment increased from 36.1 percent to 51.3 percent. By the end of the follow-up period, the incidence of bilateral giant retinal breaks was 12.8 percent; retinal tears 11.9 percent, retinal holes 10.2 percent, retinal dialysis 0.4 percent, and retinal detachment 15.9 percent. The average duration of follow-up was 3.7 years, therefore, the incidence of retinal breaks in fellow eyes is probably significantly higher. VITREORETINAL CHANGES PRECEDING THE DEVELOPMENT OF RETINAL BREAKS. Syneresis, liquefaction, and condensation of the vitreous base were observed in the majority fellow eyes that developed retinal tears or giant retinal breaks. Follow-up of fellow eyes revealed that the development of a giant retinal break is often preceded by increasing white with pressure associated with increasing condensation of the vitreous base. MANAGEMENT OF FELLOW EYES. Bcause of the high incidence of retinal breaks developing in the fellow eye, regular and thorough examination of the vitreous and retinal breaks even though the fundus may appear normal at the initial examination. PROPHYLACTIC TREATMENT. This study suggests that prophylactic treatment is beneficial in the management of fellow eyes of giant retinal breaks. During this study, retinal breaks developed in 27.3 percent of untreated eyes and in 2.4 percent of eyes treated prophylactically. PROPHYLACTIC TREATMENT OF FELLOW EYES OF GIANT RETINAL BREAKS. Its seems prudent to prophylactically treat retinal holes or dialyses in eyes without retinal detachment with cryotherapy. Scleral bucking seems justified in the prophylactic treatment of eyes with retinal tears of lattice-like degeneration with retinal breaks or highly myopic eyes with increasing white with pressure and increasing condensation of the vitreous base.

Adolescent↗
PubMed1975

Vitreous surgery. XII. New instrumentation for vitrectomy.

An improved instrument for removing vitreous tissue consists of a replaceable cutting tip and a micromotor that powers the cutting tip. The cutting tip consists of a helical cutter and a metallic tube housing the cutter. An automated power-control unit is also available to control evacuation, infusion, and speed of rotation of the instrument. Several devices for monitoring the outflow of evacuation material and pressure in the eye and in the evacuation line are included. The cutting tip is illuminated by a fiber-optic system, which provides an additional factor of safety. The instrument contains a cleaning mechanism that eliminates the need for disassembling the cutting tip. When an automated control unit is not available, the vitreous nibbler may be used with manual suction, gravity-controlled infusion, and a simplified control unit.

Automation↗
PubMed1975

Experimental vitreous surgery. XIII. Open-sky partial vitrectomy through pars plana incision.

The effects of an incision through the pars plana ciliaris for open-sky subtotal vitrectomy were evaluated in four groups of monkeys, with incisions ranging from 170 degrees to 240 degrees. The nasal long ciliary artery and nerve and the anterior ciliary arteries from the inferior and medial recti were left intact in all cases. Follow-up observation ranging from three to 24 months indicates that the 170 degrees incision and the longer incisions in which the temporal ciliary artery and nerve were sacrificed do not cause severe anterior segment necrosis. The advantages of the incision through the pars plana ciliaris are (1) easier approach to the vitreous cavity, (2) preservation of the crystalline lens and an intact iris, and (3) circumvention of the corneal and chamber angle complications sometimes associated with the transcorneal approach.

Animals↗
PubMed1975

The current status of vitreous membrane surgery.

The prognosis in complicated retinal detachments has improved with advances in vitreous surgery. Different types of vitreous membranes require different instrumentation and different surgical techniques. This presentation describes the indications, instrumentation and surgical techniques for the management of various types of vitreous membranes. An exhibit on vitreous surgery illustrates various instrumentation.

Eye Diseases↗