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Biomedical subjects

H Lincoff

Publications and source records attributed to H Lincoff.

At least 19 recordsLinked to original sources
PubMed2000

Intraocular concentrations of clindamycin obtained by sequential parabulbar injections.

PURPOSE: To measure the intraocular concentration of Clindamycin that can be maintained by sequential injection through a retained parabulbar catheter. MATERIALS AND METHODS: The peak intraocular concentration and half-life of Clindamycin after parabulbar injection was determined in a rabbit model. In a second experiment a parabulbar catheter was inserted and the maximum concentration that could be maintained by sequential injection through the catheter at intervals of 6 hours was determined. In a third experiment both eyes of the rabbit were catheterized and one infused with Clindamycin. The eyes were enucleated and studied by light and electron microscopy for changes induced by Clindamycin and the catheter. RESULTS: The concentration of Clindamycin after a single parabulbar injection of 10 mg/kg peaked in the retina and choroid at 2 hours and was 336 micrograms/g. The serum level at 2 hours was 2.2 micrograms/ml. The half-life in choroid and retina was 1 hour. Sequential administration at 6 hour intervals maintained a minimum concentration of 87 micrograms/ml. The vitreous concentration was maintained at 2 micrograms/ml. CONCLUSION: The level of Clindamycin in the retina and choroid obtained by sequential injections of 10 mg/kg exceeds the minimum lethal dose for organisms susceptible to the drug. The low serum concentration suggests that sequential doses of Clindamycin by the parabulbar route might be an effective therapy for toxoplasmic retinochoroiditis and would diminish the risk of colitis or other deleterious systemic side effects.

Animals↗
PubMed2000

Changing patterns in the surgery for retinal detachment: 1929 to 2000.

PURPOSE: To examine the development of surgery for retinal detachment in this century and to determine whether the countless innovations and modifications fall into a recognizable pattern. MATERIALS AND METHODS: The authors, whose entire professional life has been devoted to the treatment of retinal detachment, have made a retrospective analysis of their experience in the field of retinal surgery. They have reviewed their notes of the annual meetings of the Retina Society, the Retinological Society, and the biennial meetings of the Gonin Club, all of which they attended, and augmented this with an in-depth review of the literature. RESULTS: Four conceptual advances by Jules Gonin, Bengt Rosengren, Ernst Custodis and Robert Machemer and countless modifications by a new category of specialists, the retinal surgeons, merge into two general patterns for the surgical repair of retinal detachment. The one is a local operation confined to closing the retinal breaks, the other is a circumferential operation intended to barricade the breaks and the peripheral retina. Both were extraocular operations. The more recent intraocular procedures, pneumatic retinopexy and vitrectomy, although apparently unique, nevertheless, fall into one or the other pattern. CONCLUSIONS: Surgery for retinal detachment has improved the prognosis from 0% before 1929 to near 100%. Reducing morbidity and the incidence of reoperation remain a worthy objective for the coming century.

Germany↗
PubMed1999

Intravitreal gas injection diminishes hyaluronic acid.

OBJECTIVES: To determine if compression of the vitreous by an intraocular gas bubble diminishes the concentration of hyaluronic acid (NaHA). MATERIALS AND METHODS: Eighteen albino rabbits had air, xenon or perfluoroethane (C2F6) injected into the vitreous to displace 12.5% to 90% of the vitreous volume. After the gas was absorbed, the vitreous was analyzed for NaHA by the Carbazole method (1, 13). RESULTS: A 90% displacement diminished the NaHA concentration by 18.6%. Lesser displacements caused a lesser loss, but the differences are not significant. CONCLUSION: Intraocular gas injections, both large and small, reduce the concentration of NaHA and destabilize the vitreous structure.

Air↗
PubMed1998

A new chart for planning retinal surgery.

PURPOSE: To design a chart for drawing retinal detachments that minimizes the circumferential distortion that occurs with the current chart. METHODS: After trying several standard map projections, a hybrid chart was created. It retains the radial equidistant projection of the current chart from the posterior pole to the equator, but superimposes stereographic projection anterior to the equator. The hybrid chart was put on trial for drawing retinal lesions and planning retinal detachment surgery at the New York Hospital and at the University Eye Clinic in Tübingen in May 1992. RESULTS: The stereographic projection anterior to the equator has minimized the distortion of retinal breaks and other pathology in the anterior retina when drawn on the chart. Retinal breaks can be drawn as they are seen ophthalmoscopically and estimates of their real dimensions derived from the chart. CONCLUSION: A new retinal chart that minimizes circumferential distortion anterior to the equator has proven advantages for planning retinal detachment surgery.

Humans↗
PubMed1998

Optical coherence tomography of pneumatic displacement of optic disc pit maculopathy.

BACKGROUND: The authors have previously concluded that fluid from an optic disc pit creates an inner layer separation (ILS) of the retina. An outer layer detachment (OLD) centred on the macula is a secondary phenomenon that causes a dense central scotoma. Pneumatic displacement of the OLD effects an improvement in central vision. Pathology to confirm these conclusions is lacking. Intraretinal images obtained by optical coherence tomography (OCT), however, are confirmatory. METHODS: Three patients with optic disc pit maculopathy were studied with stereoscopic photographs, visual fields, and OCT before and after intravitreal gas was injected to displace the central retinal elevation to below the inferior temporal vascular arcade. RESULTS: Preoperatively, OCT demonstrated an ILS that connected with the optic disc pit. External to it was an OLD that centred on the fovea and did not connect with the optic disc pit. Pneumatic displacement of the OLD was accompanied by an improvement in central vision. Long term follow up indicates that the effect of displacement may be temporary. CONCLUSION: OCT confirmed the two layer structure of optic disc pit maculopathy and that the improvement in central vision after pneumatic displacement coincides with a reattachment of the OLD in the macula. It also supports the hypothesis that the ILS, which persists, provides a conduit for the continuous flow of fluid from the pit to the displaced retinal elevation.

Adult↗
PubMed1996

Optic coherence tomography of optic disk pit maculopathy.

PURPOSE: To define the structure of optic disk pit maculopathy. METHODS: A patient was examined with optic coherence tomography before and after an intravitreal gas tamponade. RESULTS: Before intravitreal gas injection, optic coherence tomography defined a separation between the inner and outer layers of the retina that connected with the optic disk pit. An outer retinal layer detachment that centered on the fovea was also present. After pneumatic displacement of the intraretinal and subretinal fluid, optic coherence tomography disclosed that the two layers were opposed and in contact with the retinal pigment epithelium. CONCLUSIONS: Optic coherence tomography confirmed the two-layer structure of optic disk pit maculopathy and demonstrated the positive effect of pneumatic displacement.

Humans↗
PubMed1996

Extraocular repeat surgery of retinal detachment. A minimal approach.

BACKGROUND: After a failed buckle surgery, the second procedure tends to be a gas injection and the third a vitrectomy. METHODS: The failures from two series, consisting of 752 and 500 buckle surgeries, were analyzed for cause, solution, and outcome after repeat surgery with a segmental or encircling buckle. RESULTS: The most frequent cause of failure was an undetected break. An analysis of the postoperative contour of the detachment suggested its presence and helped to locate it. Failure occurred nearly as frequently because the buckle was inadequate. It was poorly placed, too narrow, or too shallow. An undetected break or an inadequate buckle was the cause of 73% of the failures in the first series and 79% of failures in the second series. The failure from either cause responded, with few exceptions, to a segmental explant. CONCLUSION: The arbitrary sequence of intraocular gas and then vitrectomy in response to failure to attach the retina with a scleral buckle often is misdirected.

Catheterization↗
PubMed1996

Choroidal concentration of interferon after retrobulbar injection.

PURPOSE: To determine whether recombinant human interferon alpha-2a (IFN alpha-2a) would diffuse into the choroid in significant amounts from a retrobulbar depot. METHODS: One million international units of IFN alpha-2a were injected into the retrobulbar space of the eyes of 17 rabbits, and choroidal and serum concentrations were measured at 1, 2, 4, 8, 12, and 24 hours. The same dose of IFN alpha-2a was injected subcutaneously into 10 rabbits, and choroidal and serum concentrations were measured at the same intervals for comparison. Parabulbar and ocular tissues were studied by light microscopy for evidence of local toxicity. RESULTS: Peak concentration IFN alpha-2a in the choroid after retrobulbar injection occurred at 2 hours and averaged 32,000 IU/mg. Peak concentration in the serum occurred at 4 hours and averaged 227 IU/ml. Concentrations in choroid and serum fell rapidly, and IFN alpha-2a was not detectible at 24 hours. No IFN alpha-2a was detected in the choroid of the paired eye, and only a trace (< 50 IU/mg) was found in either eye after subcutaneous injection. Light microscopy revealed some lymphocytes in the fat adjacent to the retrobulbar depot after six daily injections of IFN alpha-2a or saline. Sclera, choroid, and retina appeared unaffected. CONCLUSIONS: IFN alpha-2a diffuses into the choroid from a retrobulbar depot in significant amounts. The serum concentration from a retrobulbar injection is < 1% of the choroidal concentration. The retrobulbar route to the choroid may be optimal for testing the effect of IFN alpha-2a on choroidal neovascularization.

Animals↗
PubMed1994

Finding the retinal hole in the pseudophakic eye with detachment.

The recently developed wide-field indirect contact lenses, recommended and used for pancoagulation of the retina posterior to the equator, have proved to be unexpectedly advantageous for finding retinal breaks anterior to the equator in the pseudophakic eye. Through a 6-mm pupil, it is possible with some ocular rotations, tilting of the lens, and scleral depression to bring into view the retina anterior to the equator and frequently the ora serrata. We found or confirmed 45 small retinal breaks anterior to the equator in 24 retinal detachments in pseudophakic eyes with the wide-field indirect contact lens. The indirect contact lens eliminates the blur that occurs when viewing through the edge of the intraocular lens, and its image suffers less interference from lens and capsular opacities.

Cataract Extraction↗
PubMed1993

Improvement in visual function after displacement of the retinal elevations emanating from optic pits.

OBJECTIVE: To define the functional deficit that correlates with the inner layer separation and the outer layer detachment that have been observed in optic pit maculopathy and to determine the effect of a gas tamponade that compresses or displaces the two layers. DESIGN: The central visual field before and after a gas tamponade on the posterior pole were charted on a 1-m tangent screen and compared with the changes in the retina observed biomicroscopically and with stereophotography. SETTING: The gas operations were done at four hospitals in the New York, NY, area and one in Cleveland, Ohio. The retinal examinations, visual field testing, and stereoscopic photography for eight patients were done at The New York Hospital. The patient who lived in Cleveland was examined and photographed in Cleveland. PARTICIPANTS: Nine patients between the ages of 18 and 46 years with optic pit maculopathy. INTERVENTION: The patients were operated on by five retinal surgeons with a variety of procedures. Four patients had a vitrectomy and intraocular gas injected. Five patients had gas injected after external compression. Two patients had laser applied in conjunction with the intraocular injection. The gas tamponade was the unifying factor. RESULTS: The dense central scotoma in optic pit maculopathy relates to the outer layer detachment and displacement of it from the posterior pole yields an improvement in visual acuity. The inner layer separation persists centrally after a gas tamponade and continues to provide access for the flow of fluid from the pit. The scotoma that relates to the inner layer separation is mild and consistent with relatively good visual acuity.

Adolescent↗
PubMed1992

Tractional elevations of the retina in patients with diabetes.

Tractional retinoschisis and tractional retinal detachment are both complications of proliferative diabetic retinopathy. The two conditions are frequently confused because they are similar in diagnostic features. We determined the respective incidence of tractional retinoschisis and tractional retinal detachment in 200 eyes with tractional elevations of the retina in patients with diabetes. In 39 eyes, the diagnosis was unequivocally tractional retinoschisis because the retinal elevation maintained its concave contour despite the development of retinal holes. In 65 eyes, tractional retinal detachment was diagnosed with equal certainty, either because pigment lines were present or because the elevation, after a retinal hole developed, rapidly became convex and extended to the ora serrata. The remaining 96 eyes, in which retinal holes or pigment lines were absent, were classified by other features that had been tested for significance in the already diagnosed eyes. On that basis, the diagnosis was retinoschisis in 46 eyes and retinal detachment in 50 eyes.

Diabetes Mellitus, Type 1↗
PubMed1992

Longevity of expanding gases in vitrectomized eyes.

The effect of lensectomy and vitrectomy on the disappearance of intraocular gas was studied in a rabbit model. Ten rabbits underwent lensectomy and vitrectomy in one eye, and ten others underwent vitrectomy alone in one eye. The second eye of each rabbit served as a control. Equal amounts of perfluorocarbon gas, either perfluoromethane (CF4) or perfluoromethane (C2F6), was injected into both eyes of the 20 animals. After an interval corresponding to one or more half-lives of the gases had elapsed, the residual volumes of gas in the paired eyes were measured directly by an invasive method and compared. The volume of gas in the aphakic vitrectomized eye was 1.3 times greater, on average, than in the paired control eye. There was no significant difference between eyes that had undergone only vitrectomy and the control eyes. It is postulated that vascular congestion and decreased aqueous secretion caused by surgical trauma were responsible for the delay in the disappearance of gas in the eyes that underwent both lensectomy and vitrectomy.

Animals↗