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Biomedical subjects

S A Obstbaum

Publications and source records attributed to S A Obstbaum.

At least 73 records · Page 4Linked to original sources
PubMed1988

The evaluation of corneal endothelial permeability in PERK study patients.

Sixteen patients enrolled in the PERK study were evaluated by fluorophotometry 24 hours or six months following radial keratotomy. A comparison of eyes operated and not operated upon showed that endothelial permeability was not significantly altered 24 hours and six months after surgery. Aqueous humour flow rates and anterior chamber elimination coefficients were significantly higher 24 hours after surgery in the eyes operated on than in those not operated on. Six months after surgery there was no longer a significant difference in these factors. The increase in aqueous humour flow rates 24 hours after surgery may represent a subclinical breakdown in the blood-aqueous barrier.

Adult↗
PubMed1987

Three-year results of the Prospective Evaluation of Radial Keratotomy (PERK) Study.

The Prospective Evaluation of Radial Keratotomy (PERK) study is a nine-center clinical trial of a standardized technique of radial keratotomy in 435 patients who had simple myopia with a preoperative refractive error between -2.00 and -8.00 diopters (D). The authors report results for one eye of each patient. The surgical technique consisted of eight incisions using a diamond micrometer knife with the blade length determined by intraoperative ultrasonic pachymetry and the diameter of the central clear zone determined by the preoperative refractive error. At 3 years after surgery, 58% of eyes had refractive error within 1.00 D of emmetropia; 26% were undercorrected and 16% were overcorrected by more than 1.00 D. Uncorrected visual acuity was 20/40 or better in 76% of eyes. The operation was more effective in eyes with a preoperative refractive error between -2.00 and -4.37 D. Between 1 and 3 years after surgery, the refractive error changed by 1.00 D or more in 12% of eyes, indicating a lack of stability in some eyes. In the 435 eyes, there was a small number of complications including six eyes that lost two or three lines of best-corrected acuity, 16 that experienced vascularization of the incisions, 2 that had delayed bacterial keratitis, and 4 that had recurrent epithelial erosions.

Follow-Up Studies↗
PubMed1986

Glaucoma and intraocular lens implantation.

Extracapsular cataract extraction with posterior chamber intraocular lens implantation is a viable method to rehabilitate the glaucoma patient with a cataract effectively. The success with this procedure in uncomplicated cases is translated into excellent results in the glaucomatous eye. This paper reports the results of extracapsular cataract extraction with posterior chamber intraocular lens implantation in four groups of glaucoma patients: (1) chronic open-angle glaucoma; (2) angle-closure glaucoma; (3) after argon laser trabeculoplasty; (4) after filtering procedures. The visual acuity after this surgical procedure improved to 20/40 or better in 86% of patients. Intraocular pressure was controlled in all groups at a level approaching the preoperative value. Ninety percent were controlled with equal or less medication than that used preoperatively. There has been no significant progression of optic nerve cupping or visual field loss.

Aged↗
PubMed1985

Results of the prospective evaluation of radial keratotomy (PERK) study one year after surgery.

The Prospective Evaluation of Radial Keratotomy (PERK) study is a nine-center, self-controlled clinical trial of a standardized technique of radial keratotomy in 435 patients who had physiologic myopia with a preoperative refraction between -2.00 and -8.00 diopters. The surgical technique consisted of eight incisions using a diamond micrometer knife with blade length determined by intraoperative ultrasonic pachymetry and the diameter of central clear zone determined by preoperative refraction. At one year after surgery, myopia was reduced in all eyes; 60% were within +/- 1.00 diopter of emmetropia; 30% were undercorrected and 10% were overcorrected by more than 1.00 diopter (range of refraction, -4.25 to +3.38 D). Uncorrected visual acuity was 20/40 or better in 78% of eyes. The operation was most effective in eyes with a refraction between -2.00 and -4.25 diopters. Thirteen percent of patients lost one or two Snellen lines of best corrected visual acuity. However, all but three eyes could be corrected to 20/20. Ten percent of patients increased astigmatism more than 1.00 diopter. Disabling glare was not detected with a clinical glare tester, but three patients reduced their driving at night because of glare. Between six months and one year, the refraction changed by greater than 0.50 diopters in 19% of eyes.

Adult↗
PubMed1985

Laser trabeculoplasty and cataract surgery.

We have compared long-term intraocular pressure control in patients with open angle glaucoma, cupping and atrophy of the optic nerve head and visual field loss as well as cataract after: trabeculectomy posterior to the scleral spur and cataract extraction without implantation in 108 patients. guarded posterior lip sclerectomy, cataract extraction and Mark VIII or Mark IX anterior chamber implantation in 28 patients. argon laser trabeculoplasty followed by lens extraction and implantation in 27 patients. Approximately 75 per cent of patients achieve intraocular pressures of 18 mm Hg or less without medication after (a), and approximately 40 per cent of patients achieve similar control without medication after (b). Approximately 25 per cent of these glaucoma patients have intraocular pressure levels of less than or equal to 18 mm Hg on topical medication three months after ALT, and none achieve this control without medication. Cataract surgery with anterior or posterior chamber implantation caused loss of topical control in four of the seven patients benefiting from ALT. These data imply that combined surgery with or without implantation produces better and more significant intraocular pressure control than the presently utilized techniques of ALT subsequently followed by lens extraction and implantation.

Anterior Chamber↗
PubMed1985

Trabeculectomy, cataract extraction and intra-ocular lens implantation.

Seventeen cases of open-angle glaucoma requiring cataract extraction underwent intracapsular cataract extraction, trabeculectomy posterior to the scleral spur, and MK9 intraocular lens insertion. Approximately 50 per cent of the patients achieved intraocular pressures of 18 mm Hg or less without medication two years later. Though implantation reduces the surgical success of the combined operation, it is safe, easy to perform and does not worsen pre-operative levels of intraocular pressure and/or control.

Cataract Extraction↗
PubMed1983

Rationale for and design of the National Eye Institute Prospective Evaluation of Radial Keratotomy (PERK) Study.

A five-year, multicenter, collaborative clinical trial of radial keratotomy for myopia is being carried out at nine clinical centers. The study, funded by the National Eye Institute, is recruiting approximately 500 patients aged 21 years or older with -2.00 to -8.00 diopters of physiologic myopia who also meet other clearly defined eligibility criteria. Surgeons use a diamond-bladed micrometer knife to make eight radial incisions in the anterior cornea. The diameter of the central clear zone is determined by the amount of myopia and the depth of the incisions by intraoperative ultrasonic pachymetry. Investigators other than the surgeon gather all pre- and post-operative data. Examinations include measurement of visual acuity with standardized charts, verification of refractions by a second observer, measurement of corneal curvature by keratometry and photokeratoscopy, quantitation of glare with a glare tester, and measurement of the size of individual endothelial cells from specular photomicrographs with a computerized digitizer. A formal psychometric questionnaire is used to evaluate the patients' subjective response. Physician monitors insure adherence to the protocol during site visits and members of the Data and Safety Monitoring Board oversee the progress of the study. Biostatisticians at the Coordinating Center insure complete data collection, process the data, and assist in the interpretation of results.

Academies and Institutes↗
PubMed1982

Educating the implant surgeon.

Intraocular lens implantation is a remarkable advance in the visual rehabilitation of the aphakic patient. The success of implantation is linked to the quality of the cataract surgery. Methods for refined cataract extraction include microsurgery and the use of newer instrumentation. The practiced cataract surgeon and the surgeon in training must master these techniques before implantation is undertaken. Intraocular lens surgery must likewise follow a logical progression from attendance and participation at practical courses to assisting at surgery, to implanting with an experienced intraocular lens surgeon present to monitor and assist, if necessary. As with any new technique, a variety of ancillary advances develop which also require understanding and expertise on the part of the surgeon. These affect judgmental decisions which become as important as the actual surgery. The field of implantation has continued to grow by providing new information on a variety of subjects. The novice implant surgeon, as well as the experienced implant surgeon, must constantly be aware of these advances and strive to master the techniques of this exciting and valuable field.

Cataract Extraction↗
PubMed1982

The long term effect of an iris-supported lens on the endothelium.

A retrospective study of 104 eyes that had iris-supported Sputnik intraocular lenses implanted and no surgery in the fellow eye and a separate series of 30 implanted eyes whose second eyes underwent surgery but did not receive implants disclosed that endothelial cell densities in the eyes with implants decreased immediately after surgery and then continued to decrease at the same rate as those of the control eyes. There was no sudden decrease in the endothelial cell counts during follow-up periods ranging from three to seven years. The main cause of large cell losses immediately after surgery, and possibly long-term corneal decompensation, was surgical manipulation rather than the presence of this style of intraocular lens.

Cell Count↗
PubMed1981

Management of glaucoma in the implanted patient.

Implanting an intraocular lens in an eye with controlled open angle glaucoma or angle closure glaucoma does not adversely affect the eye's status. Furthermore, it is extremely rare for primary glaucoma to develop in an eye postimplantation. Secondary glaucoma is certainly more common, although its incidence is not substantially greater than that in nonimplanted eyes. Special considerations with respect to medical therapy and surgical treatment of secondary glaucoma in pseudophakia are discussed.

Aphakia, Postcataract↗
PubMed1981

Laser photomydriasis in pseudophakic pupillary block.

Pupillary block glaucoma is a potential complication of implantation. Early recognition and prompt medical therapy will generally successfully treat the condition. In some instances surgical treatment is required if medical therapy is inadequate. Laser iridectomy and laser photomydriasis are other alternatives to surgical therapy. This case reports successful treatment of pseudophakic pupillary block glaucoma using laser photomydriasis.

Aged↗
PubMed1981

Combined surgery for cataract and open-angle glaucoma.

Seventy-five percent of patients with open-angle glaucoma and cataract will not require medication at the 2-year period after a cyclodialysis canaliculo-trabeculectomy cataract extraction; this is in contrast to simple cataract extraction, which has a success rate of approximately 12 percent. The absence of significant morbidity and the predictability of the procedure recommend it for all patients with open-angle glaucoma needing cataract extraction, not simply those with inadequate glaucoma control.

Anterior Chamber↗
PubMed1981

Why do implants fail?

Nylon 66 and polypropylene are chemotactic in human serum while PMMA from intraocular lenses is not. Chemotactic activity is unaltered by Ridley, 5 per cent NaOH, or ethylene oxide sterilization. Chemotaxis is but one manifestation of an overall inflammatory process that may be involved in implant-induced corneal and retinal dysfunction.

Adult↗
PubMed1981

Hospitalization and cataract surgery.

A population of 250 age-matched cataract patients was studied to determine if hospitalization was required for cataract extraction. The success of the procedure was not jeopardized if immediate ambulation was effected and postsurgical care carried out entirely on an ambulatory basis in a nonhospital environment. The cost containment potential of this approach cannot be readily achieved in the face of existing regulatory systems and insurance requirements.

Aged↗
PubMed1980

Mechanism of implant inflammation.

Polymethylmethacrylate lenses with nylon-6 loops can activate the complement system. Such activation occurs primarily at the loops. This activation may be one pathway of implant-caused inflammation.

Complement Activation↗
PubMed1979

Cataract extraction in glaucoma.

Cyclodialysis lens extraction or cyclodialysis canalicular trabeculectomy lens extraction in one eye and cataract extraction in the fellow eye were performed in 24 glaucoma patients. The combined procedure follow-up was from five to 12 years in the first group, two to four years in the second group, and from three to ten years in the control group. The 50% success rate of cyclodialysis lens extraction can be enhanced with no significant increase in surgical morbidity or postoperative complications by performing a cyclodialysis canalicular trabeculectomy where the disinsertion of the scleral spur is carried out under direct visualization.

Aged↗