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Biomedical subjects

G Treister

Publications and source records attributed to G Treister.

At least 37 records · Page 2Linked to original sources
PubMed1996

Role of blood components in ocular silicone oil emulsification. Studies on an in vitro model.

PURPOSE: To develop an in vitro model for silicone oil emulsification and to explore the blood components involved in this process. METHODS: The capacity of various blood components to support silicone oil (1000 CS) emulsification was studied by applying 0.5 ml oil on top of 0.5 ml saline containing various blood components. Each tube was sonicated for 150 seconds and centrifuged at 5000 g for 20 minutes. Three phases were noted in the tube: At the top was clear silicone oil, in the middle was emulsified silicone oil, and at the bottom was aqueous solution. The tubes were photographed, and the percentage of the phase length containing emulsified silicone oil (middle) of the total length of the three phases was calculated from the projected image of each tube. RESULTS: Emulsified silicone oil in plasma or serum was initiated after 100 seconds of sonication and quickly reached maximum (approximately 80%) at 120 seconds. The size of these oil droplets prepared in vitro was 0.0467 +/- 0.028 mm, closely resembling that observed in oil samples removed from a patient's anterior chamber (0.038 +/- 0.018 mm). Under these conditions, silicone oil emulsified in the presence of whole blood cells occurred only at a concentration of 120 micrograms protein/ml; in the presence of red blood cell membranes, it occurred at a concentration of 60 micrograms protein/ml. Lipoprotein-deficient serum failed to support emulsification; however, samples of high-density lipoprotein and low-density lipoprotein supported this process. Purified high-density lipoprotein-apolipoproteins supported oil emulsification. The addition of phosphatidylcholine further enhanced this process, but phosphatidylcholine alone failed to support emulsification. CONCLUSIONS: A simple and fast in vitro model to study factors affecting silicone oil emulsification was developed. Using this model, red blood cell membranes, plasma lipoproteins, and purified HDL-apolipoproteins supported silicone oil emulsification. Lipids did not, but they had the capacity to enhance the apolipoprotein-supported emulsification.

Blood Cells↗
PubMed1995

The impact of the macular photocoagulation study results on the treatment of exudative age-related macular degeneration.

OBJECTIVE: To determine the percent of cases with all primary forms of exudative age-related macular degeneration that are eligible for treatment by the Macular Photocoagulation Study (MPS) guidelines in a retina clinic serving both as a primary care center and as a referral center. DESIGN: Fluorescein angiograms of patients with age-related macular degeneration examined at the Goldschleger Eye Institute, Sheba Medical Center, Tel Hashomer, Israel, during a 5-year period (1985 to 1990) were randomly selected and reviewed. Angiograms showing all forms of exudative age-related macular degeneration were eligible. The first 100 eligible angiograms identified constituted the study series and were classified into four groups: active choroidal neovascularization (CNV), pigment epithelium detachment, hemorrhage, and disciform scars. The active CNVs were further divided into three subgroups: classic (well defined), occult (poorly defined), and combined. Eligibility for laser treatment was determined exclusively with use of the published MPS recommendations for treatment of extrafoveal, juxtafoveal, and subfoveal membranes. RESULTS: There were 10 cases in the pigment epithelium detachment group, 11 cases in the hemorrhagic group, and 16 cases with disciform scars. All of these 37 cases were ineligible for treatment by MPS guidelines. Sixty-three eyes had active membranes; 37 were classic CNVs (eight extrafoveal, seven juxtafoveal, and 22 subfoveal). All extrafoveal and juxtafoveal CNVs were found to be eligible for laser treatment. Eleven membranes of the subfoveal group were larger than 2 disc areas, a size for which the MPS did not demonstrate benefit from laser treatment. There were 19 membranes in the strictly occult CNV subgroup, all of them untreatable by MPS criteria. Seven cases had both occult and classic CNV, and all were larger than 3.5 disc areas and therefore ineligible for treatment. Overall, 26 cases were eligible for treatment by strict MPS criteria; these constitute 26% of the whole series and 41% of the active CNV cases in the series. CONCLUSIONS: Our results indicate that the MPS guidelines for laser treatment are applicable only to a minority of the cases with exudative age-related macular degeneration presenting to our clinic. Further studies should be conducted to identify additional treatment modalities for this common eye disease.

Choroid↗
PubMed1993

Long-term follow up of accidental parafoveal laser burns.

The findings after 12 years of follow-up evaluation of 2 patients who sustained accidental parafoveal and juxtafoveal Nd:YAG laser injuries are reported. In both cases, the fovea was not destroyed by the initial insult and early scar formation. Both cases demonstrated, after more than a decade, minimal visual deficit without significant late complications. In spite of early decrease in visual performance, the long-term prognosis for Q-switched Nd:YAG laser retinal lesions in which the fovea was not directly involved in the injury or its repair mechanisms is relatively benign.

Adult↗
PubMed1993

Removal of silicone oil in the management of glaucoma in eyes with emulsified silicone.

Glaucoma and emulsification are two complications of silicone oil injection that are often coexisting. This study was undertaken to determine whether removal of emulsified oil has any effect on the management of the glaucoma. A comparison of eyes with and without glaucoma with emulsified oil also was undertaken. Eighteen eyes that underwent removal of emulsified silicone oil more than 6 months after the injection of the oil were reviewed. All eyes were observed for at least 6 months after removal with attached retinas. Eleven eyes had glaucoma at the time of removal. The diagnosis of glaucoma preceded the identification of emulsification in 8 of 11 eyes (73%). Removal of the emulsified oil did not affect the intraocular pressure (IOP) in 10 of the 11 (91%) glaucomatous eyes. The IOP was reduced in one patient. In the glaucoma patients, the final visual acuity was significantly reduced compared with the best corrected visual acuity obtained during the follow-up period (P = 0.016). In the nonglaucoma eyes with emulsified oil, the visual acuity did not significantly deteriorate during follow-up. At the end of the follow-up period, optic atrophy was observed in 9 of 11 (82%) of the eyes with glaucoma compared with two of seven (28%) of eyes without glaucoma. The results suggest that removal of emulsified silicone oil failed to control the glaucoma, and could not change the aggressive nature of the glaucoma in these eyes.

Adult↗
PubMed1993

Methylcellulose as a contact lens irrigant when silicone oil is used in vitreoretinal surgery.

When silicone oil, a hydrophobic agent, is injected into the vitreous cavity during the course of vitrectomy operations, often some escapes outside the eye, and a mixture of oil and water forms under the infusion contact lens, markedly interfering with visibility. We found that a viscous solution of methylcellulose 1.75% in saline used as the infusion contact lens irrigant, instead of a saline solution alone, can prevent silicone oil from entering under the contact lens, thus avoiding this difficulty.

Contact Lenses↗
PubMed1992

[Treatment of retinal detachment with intraocular expandable gas injection].

The injection of expandable gas into the vitreous is a new method for treating retinal detachment. The injected gas bubble seals the retinal break and allows absorption of subretinal fluid. In 12 patients, in all eyes treated by injection of sulfur hexafluoride, the detached retina became reattached. In 3 eyes (25%) detachment recurred. To achieve attachment again, both vitrectomy and the circling band operation were performed in 2 of them, and only the latter operation in the third. Risk factors for redetachment included detachment of the macula, retinal detachment larger than 5-o'clock-hours, and pseudophakia. Proper selection of patients for gas injection is most important.

Gases↗
PubMed1992

Cataract extraction in eyes filled with silicone oil.

A surgical technique for cataract extraction in eyes filled with silicone oil was developed that has two major objectives: removal of the entire cataractous lens and complete preservation of the silicone oil volume. A regular extracapsular cataract extraction or phacoemulsification is performed, and the incision is closed with the final sutures. All steps are performed under continuous positive pressure achieved with an anterior chamber maintainer connected to a bottle of balanced saline solution. An inferior basal iridectomy is created with a vitrectomy probe, and the posterior capsule is then slowly pulled out through the limbal incision with intraocular forceps, again under positive pressure, in an eye that is actually a closed system, without any loss of silicone. This step results in transformation of the extracapsular cataract extraction condition into an intracapsular cataract extraction condition. The described technique was successfully performed in nine eyes. In the younger patients, the whole procedure was completed through two very small limbal openings.

Adult↗
PubMed1992

Immediate retinal adhesion by CO2 laser irradiation using a fiberoptic intraocular probe.

Using an experimental fiberoptically guided CO2 laser system, we produced lesions on fresh bovine retinas. These lesions were shown to achieve immediate measurable chorioretinal adhesion. This model provides preliminary data on the use of a fiberoptic CO2 laser probe to produce chorioretinal lesions and possible future use in intraocular surgery for retinal detachment. The advantages of using CO2 laser energy are minimal damage surrounding desired lesion and its versatility as a coagulator and cutter. With modifications, CO2 endolaser may have a role in intraocular surgery.

Animals↗
PubMed1992

A quantitative in vitro model for silicone oil emulsification. Role of blood constituents.

To understand why some patients seem to be protected from emulsification and others are not, the authors developed an in vitro model for quantitative analysis of silicone oil emulsification. The pro-emulsifying potential of substances and blood components that may have access to the vitreous cavity in a patient's eye was analyzed. In this model, red blood cell ghosts had the highest emulsifying effect; plasma and lymphocytes also had a significant emulsifying effect. Phospholipids in membranes and other soluble blood components may play important roles in this process. These results suggest the importance of avoiding and removing hemorrhage and avoiding inflammation when silicone oil is used in vitreoretinal surgery.

Blood Cells↗
PubMed1992

Continuous control of intraocular pressure in pseudophakic retinal detachment surgery.

We describe a method for continuous control of intraocular pressure in pseudophakic retinal detachment surgery done shortly after extracapsular cataract extraction and posterior chamber intraocular lens implantation. The system consists of a special needle inserted into the anterior chamber through the corneal limbus. The needle is attached by a regular intravenous administration set to an infusion bag. This allows fluids to exit the eye when the eyeball is compressed and to return to the eye when pressure on the eye is released. The presence of an intact posterior capsule and an intraocular lens do not impose a significant barrier to the passage of fluids between the anterior chamber and the vitreous cavity. Using this technique, intraocular pressure can be stabilized throughout the operation. The implementation of this system is demonstrated by a case report.

Cataract Extraction↗
PubMed1991

Identification, prevention, and treatment of silicone oil pupillary block after an inferior iridectomy.

We treated two patients in whom silicone oil pupillary block developed despite a patent inferior iridectomy. The clinical characteristics of this complication were a deep anterior chamber, specular reflexes from the iris surface, identification by biomicroscopy of aqueous trapped inferiorly in the vitreous cavity, and no convection currents in the anterior chamber. This complication may be prevented by early face-down positioning of the patient after the operation, and the avoidance of large, centrally located, inferior iridectomies. We recommend that the iridectomy be placed peripherally no larger than 2 mm and propose a new technique for breaking the silicone oil block, which was clearly successful in one of the patients.

Anterior Chamber↗
PubMed1991

Sclera-directed knot technique for securing an encircling band in retinal surgery.

The protruding ends of sutures used to secure the ends of the silicone rubber band placed during many retinal surgical procedures may cause postsurgical irritation, since with presently used suturing techniques, the knot of the suture remains on top of the band, facing the conjunctiva. We describe a suturing technique which, by inverting the band when suturing its ends and then allowing the band to return to its original position, places the knot on the undersurface of the band, against the sclera. Thus, no protruding suture ends are left facing the conjunctiva and the irritation resulting from such a protrusion is averted.

Humans↗
PubMed1991

Intravitreal suture: a complication of pterygium surgery.

Among the complications associated with pterygium surgery, scleral perforation is mentioned in cases where subconjunctival tissue must be separated from the sclera. We present a case in which such a perforation and consequent suturing resulted in an intravitreous migration of a suture. We believe this is the first report of such a complication following pterygium surgery.

Female↗
PubMed1991

The intravitreal penetration of orally administered ciprofloxacin in humans.

To evaluate the penetration of ciprofloxacin, a new wide-spectrum oral antibiotic, into the vitreous, ciprofloxacin was administered orally to 21 patients who were scheduled to undergo vitreal surgery. Seven patients received 750 mg ciprofloxacin 4 hr before surgery (group I), seven patients received this dose 8 hr before surgery (group II), and seven patients received two 750-mg doses of oral ciprofloxacin every 12 hr. The last dose was administered 12 hr before surgery (group III). Vitreous and blood samples were collected simultaneously and assayed for ciprofloxacin concentrations by bioassay and high-performance liquid chromatography.

Administration, Oral↗