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Biomedical subjects

M E Hammer

Publications and source records attributed to M E Hammer.

18 recordsLinked to original sources
PubMed1997

An investigation of the hospital charges related to the treatment of endophthalmitis in the Endophthalmitis Vitrectomy Study.

PURPOSE: The purpose of the study is to assess the hospital charges associated with the treatment of endophthalmitis using a sample of patients from the Endophthalmitis Vitrectomy Study (EVS). METHODS: The Endophthalmitis Vitrectomy Study was a multicenter, randomized clinical trial with a two-by-two factorial design to compare immediate pars plana vitrectomy to tap-biopsy and to compare the use of systemic antibiotics (intravenous) to no intravenous antibiotics in the management of postoperative endophthalmitis. Hospital charge data were collected retrospectively from 129 patients from the 4 clinical centers participating in this ancillary study. This represents 31% of the total Endophthalmitis Vitrectomy Study population. An analysis of variance was used to compare hospital charges across center and treatment. A charge-effectiveness analysis compared measures the effectiveness across treatment groups. The annual savings of hospital charges in the United States was estimated for a range of annual incidence rates of endophthalmitis. RESULTS: The use of intravenous antibiotics significantly increased hospital charges. Patients undergoing vitrectomy had significantly higher hospital charges than did patients undergoing tap-biopsy. The most charge-effective treatment for patients presenting with light perception only vision was immediate vitrectomy, whereas the most charge-effective treatment for patients presenting with better vision was tap-biopsy. Factors other than treatment independently associated with hospital charges were female sex, history of diabetes, symptom of red eye, and baseline vision of light perception only. CONCLUSIONS: Assuming the results of the Endophthalmitis Vitrectomy Study were used as a guide for the treatment of endophthalmitis, the estimated annual nationwide reduction of hospital charges would be between $7.6 million and $40.0 million.

Aged↗
PubMed1997

Subretinal microsurgery with gradient index endoscopes.

State-of-the-art subretinal surgery involves a standard three-port pars plana entry, followed by an iatrogenic retinotomy to access the subretinal space. Subretinal manipulations through a small retinotomy are made possible by specially designed instruments. As the surgeon looks through the vitreous cavity, all subretinal maneuvers are obscured by the overlying retina. Consequently, the surgeon is operating 'blindly' and has to rely on 'feeling' rather than direct visualization. Micro-endoscopic viewing systems are the ideal solution for visualization during subretinal surgery. Until now, such endoscopes were either too large for intraocular use or lacked sufficient resolution, especially at a short working distance. Recently, a gradient index (GRIN) endoscope was developed (Insight Instruments, Inc., Lake Mary, Fla., USA) combining a small diameter (0.89 mm, 20 gauge) and incorporating excellent optical resolution, even at extremely close working distances. After ballooning a limited part of the retina without creating a retinal hole, the 20-gauge GRIN endoscope can be introduced into the subretinal space through the sclera and choroid, posterior to the pars plana. Surgical instruments can then be introduced into the subretinal space through a second neighboring sclerotomy. Thus, subretinal surgery can be performed under direct endoscopic control. As a result of direct visualization, the surgeon may perform certain surgical procedures with greater accuracy, i.e., subretinal neovascular membranes may be dissected meticulously from the neurosensory retina and retinal pigment epithelium, minimizing damage to both structures. The feeding choroidal vessel can be identified and directly coagulated, which is usually very difficult during conventional subretinal surgery. Endoscopic subretinal surgery is thus a significant improvement over conventional methods, avoiding the need for a retinotomy and increasing the safety and facility of the surgery itself.

Endoscopy↗
PubMed1995

Pneumatic retinopexy failures. Cause, prevention, timing, and management.

BACKGROUND: Pneumatic retinopexy is a procedure for reattaching the retina by injecting an expanding gas bubble and using either laser or cryopexy. The procedure is controversial because there may be a lower initial success rate, and intraocular gas may increase the risk of proliferative vitreoretinopathy. METHODS: The authors performed a retrospective review of 107 unpublished consecutive cases of pneumatic retinopexy together with a literature review of 25 statistical series with primary attention to failures. Univariate and multivariate analyses were carried out on the data set, and adjusted odds ratios for risk factors associated with failure were calculated using logistic regression. RESULTS: Initially, 74 (69%) of 107 patients had successful results, and with re-operations the success rate increased to 98%. Failure of the procedure to achieve retinal reattachment occurred soon after the initial procedure, with 86% of recorded failures occurring within the first month. The initial cause of failure was new or missed breaks in 14.9%, reopened initial breaks in 11.2%, and breaks never closed in 4.6%. Risk factors that showed a correlation with failure were patients being male (adjusted odds ratio = 2.65), eyes with preoperative visual acuity worse than 20/50 (adjusted odds ratio = 1.21), eyes with four quadrants of retinal detachment or total detachment (adjusted odds ratio = 2.03), aphakic or pseudophakic eyes (adjusted odds ratio = 1.91), and eyes with additional pathologic findings (adjusted odds ratio = 3.14). Poor visual outcome was associated with initial visual acuity less than 20/50 (adjusted odds ratio = 15.7) and eyes with four quadrants of retinal detachment or total detachment (adjusted odds ratio = 5.01). CONCLUSIONS: Failures of pneumatic retinopexy occur early in the postoperative course. Factors known to be associated with failure of retinal reattachment using scleral buckling also were associated with failure in pneumatic retinopexy. A higher success rate in females was noted, suggesting that educational efforts may need to be greater in males. Poorer visual results occurred in patients with poor initial vision and in eyes with four quadrants of retinal detachment or total detachments.

Cryosurgery↗
PubMed1995

Threshold retinopathy of prematurity. Transition from cryopexy to laser treatment.

PURPOSE: The authors studied the effectiveness of laserpexy versus cryopexy for treatment of acute retinopathy of prematurity. METHODS: Seventy-six eyes in 41 patients were treated for acute retinopathy of prematurity from January 1991 to April 1994. RESULTS: Fifty-six eyes in 30 patients had zone 2 disease. Of these 30 patients, 11 received laser treatment and 20 received cryopexy treatment; there was at least one anatomically successful eye in each patient. Twenty eyes in ten patients had zone 1 disease. Seven patients had bilateral laser treatment. Three patients had bilateral cryopexy. In seven eyes with zone 1 disease, five were treated successfully with laser. None of the three eyes with zone 1 disease treated with cryopexy were successful. CONCLUSION: Laserpexy and cryopexy are of equal efficacy in treating zone 2 disease. There is a tendency that suggests that laserpexy is more effective than cryopexy in treating zone 1 disease. Diode and argon lasers are of equal efficacy in treating zone 1 disease.

Acute Disease↗
PubMed1994

A multivariate analysis of anatomic success of retinal detachments treated with scleral buckling.

One hundred and twenty-three preoperative, intraoperative, and postoperative variables were evaluated to assess their effect on anatomic success of scleral buckling for retinal detachment. The relative importance of each variable was tested in a logistic regression equation. This equation identified ten significant variables for predicting the outcome of retinal detachment surgery. The significant variables were: preoperative proliferative vitreoretinopathy (adjusted odds ratio, AOR, 13.60), previous buckle by G.F. Hilton (AOR = 8.03), total detachment (AOR = 5.72), preoperative vitreous hemorrhage (AOR = 3.08), tension less than 10 mm Hg (AOR = 2.40), hemorrhagic complications (AOR = 2.62), previous buckles by others (AOR = 2.10), injection into the vitreous at surgery with either saline or balanced salt solution (AOR = 2.32) or air/sulfahexafluoride (AOR = 7.06), and preoperative vision less than 0.3 (20/60 or worse) (AOR = 2.14). The number of cryopexy applications was specifically tested in the equation, but while significant in a univariate analysis, it was not found to be significant in the multivariate analysis.

Cryosurgery↗
PubMed1991

Perforating ocular injuries caused by anesthesia personnel.

Between February 1988 and May 1990, the authors treated 12 perforating ocular injuries caused by anesthetic injections around the eye. All 12 injections were performed by nonophthalmologists. Eleven were performed by anesthesiologists and one by a certified nurse anesthetist. Five were caused by blunt needles and seven by sharp needles. Two of the eyes had multiple posterior exit wounds. The five eyes that had sharp needle, single perforations (i.e., one entrance wound and one exit wound) were easily managed with cryopexy, laser, or observation. All five of these eyes have a visual acuity of 20/40 or better. Six vitrectomies were performed on the five patients with single perforations caused by blunt needles; three of these eyes have a visual acuity of counting fingers or worse. The two patients who had multiple posterior exit wounds required a total of four procedures. The visual acuity in these eyes is 20/400 and light perception. Anesthesia personnel should be well trained before attempting ocular anesthesia. The use of blunt needles does not prevent ocular penetration.

Aged↗
PubMed1991

Pneumatic retinopexy. A two-year follow-up study of the multicenter clinical trial comparing pneumatic retinopexy with scleral buckling.

The authors report 2-year follow-up information on 179 of 198 eyes (90%) enrolled in a previously published multicenter, randomized, controlled clinical trial comparing pneumatic retinopexy (PR) with scleral buckling (SB) for the management of selected retinal detachments. Scleral buckling was compared with PR with regard to redetachment after the initial 6-month follow-up period (1% versus 1%), overall attachment (98% versus 99%), subsequent cataract surgery (18% versus 4%; P less than 0.05), preoperative visual acuity (no significant difference), and final visual acuity of 20/50 or better in eyes with macular detachment for a period of 14 days or less (67% versus 89%; P less than or equal to 0.05). Reoperations after a failed PR attempt did not adversely affect visual outcome. After 2 years, PR continues to compare favorably with SB.

Cataract Extraction↗
PubMed1990

The complication of pneumatic retinopexy.

There have been 26 published series with a total of 1274 detachments operated with pneumatic retinopexy. Eighty percent were reattached with a single procedure and 98% with reoperations. New breaks occurred in 13% and PVR in 4%. The complications published in 101 papers on pneumatic retinopexy in the last 5 years are analyzed as to frequency, prevention, management, and results.

Cryosurgery↗
PubMed1987

The ocular manifestations of Rocky Mountain spotted fever.

To our knowledge, this is the first report of an iris nodule in a case of Rocky Mountain spotted fever (RMSF). The iris nodule may be similar to the "typhus nodule" of the central nervous system reported at autopsy in patients with typhus rickettsial disease. Previous case reports of RMSF have emphasized either anterior uveitis or retinal vasculitis. In the case reported here, both occurred in our patient as a result of RMSF. Also, we review the ophthalmic literature on rickettsial disease.

Adult↗
PubMed1986

Logistic analysis of risk factors in acute retinopathy of prematurity.

In a prospective study of 328 high-risk neonates, we used computer-assisted logistic regression of 47 potential risk factors to study acute retinopathy of prematurity. Only four factors were significant in the logistic regression equation: ventilator hours, xanthine administration, birthweight, and maternal bleeding. Xanthine administration was identified as a new independent and significant (P less than .0001) predictor of acute retinopathy of prematurity.

Female↗
PubMed1986

Viscosity of subretinal fluid and its clinical correlations.

The viscosity of subretinal fluid is an important factor in transmitting force created by subretinal fluid motion to the retina. The variation of viscosity of subretinal fluid can explain variations in the effect of subretinal fluid motion on the retina. Pseudoplastic variation of subretinal fluid viscosity was confirmed using a cone-plate microviscometer. To explain the variability in viscosity between subretinal fluid specimens, 14 clinical variables associated with each of 46 specimens were examined. The strongest statistical relationship was between aphakia and lower viscosity.

Aphakia↗
PubMed1984

Experimental uveitis. Elicited by peptidoglycan-polysaccharide complexes, lipopolysaccharide, and muramyl dipeptide.

Uveitis could be a reaction to bacterial debris disseminated to the eye from extraocular sites of infection. In this study, we relate the composition of several bacterial components to their inflammatory properties in the eye. Groups of rabbits were injected intravitreously with peptidoglycan-polysaccharide (PG-PS) complexes isolated from group A streptococci, Escherichia coli lipopolysaccharide (LPS), or synthetic muramyl dipeptide (MDP). The lipid A region of LPS and the glycan backbone of PG are chemical analogues; MDP is the minimal biologically active subunit of PG. All of these molecules elicited uveitis as observed both clinically and histologically. The MDP elicited an acute inflammation characterized by a heterophil and monocyte infiltrate that subsided within 16 days. The PG-PS and LPS elicited chronic inflammation characterized by mononuclear and lymphocyte infiltration and severe necrosis of the retina.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1984

Viscous corneal protection by sodium hyaluronate, chondroitin sulfate, and methylcellulose.

The authors' study of the viscosities of various concentrations of sodium hyaluronate, chondroitin sulfate, and methylcellulose revealed that sodium hyaluronate and methylcellulose are pseudoplastic fluids in contrast to chondroitin sulfate, which is a Newtonian fluid. Pseudoplastic fluids are ideal for maintaining the anterior chamber, since they are more viscous at rest. Intermediate viscosity preparations of these three agents used as a thin endothelial coating gave excellent protection from intraocular lens abrasion. A highly viscous agent, eg, sodium hyaluronate 1%, in a thin layer produced extensive endothelial cell damage because it transmitted excessive shear force to the endothelium. A highly viscous agent, sodium hyaluronate 1% in a thick layer produced a physical barrier to compression with little endothelial damage. A low-viscosity agent, balanced salt solution provided insufficient protection against intraocular lens abrasion.

Animals↗
PubMed1984

The effect of intraocular dilating solution on cat endothelium.

Maintenance of pupillary dilatation can be a difficult problem. We found a dilute intraocular solution of atropine and epinephrine to be both effective and safe in inducing pupillary dilatation. No significant corneal endothelial toxicity could be demonstrated in the cat eye comparing preinjection and postinjection endothelial cell density.

Animals↗
PubMed1983

Post-traumatic fungal endophthalmitis caused by Exophiala jeanselmei.

Fungal endophthalmitis caused by dematiacious fungi is an uncommon occurrence. We report a case of fungal endophthalmitis caused by Exophiala jeanselmei following penetrating injury. This is a previously unreported etiologic agent in endophthalmitis. The infection was treated with intravitreal and intravenous amphotericin B in combination with oral 5-fluorocytosine. Although the organism was eradicated, vision was lost due to total retinal detachment.

Adult↗
PubMed1982

Retinal embolism following percutaneous femoral cerebral angiography.

A 35-year-old female without evidence of atherosclerotic vascular disease underwent percutaneous femoral cerebral angiography. Perifoveal retinal infarction by exogenous arteriolar emboli produced a permanent absolute pericentral scotoma. Strict adherence to meticulous angiographic technique may prevent such an angiographic complication.

Adult↗