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Biomedical subjects

D P Hainsworth

Publications and source records attributed to D P Hainsworth.

14 recordsLinked to original sources
PubMed2001

Temperature effect on nausea during fluorescein angiography.

PURPOSE: Nausea is the most common adverse effect of fluorescein angiography (FA). Warming of fluorescein dye before injection has been reported anecdotally to decrease nausea frequency. We examined the effect of warmed fluorescein dye on the frequency of adverse effects of FA. DESIGN: Prospective, randomized, controlled trial. PARTICIPANTS: Five hundred forty-seven angiograms performed on 394 patients; 273 were in the control group and 274 were in the study group. METHODS: Patients were alternately assigned to FA using dye at room temperature (control group) or dye prewarmed to body temperature (study group). All patients were masked to the dye temperature. After FA, patients were questioned regarding any adverse effects experienced. MAIN OUTCOME MEASURES: Presence or absence of reported nausea associated with FA. RESULTS: Adverse reactions were reported for 39 of the angiograms (7.1%), including 32 procedures for which nausea was reported (5.9%). No significant difference in the frequency of adverse reactions was found between the two groups (P = 0.41). No significant difference in the frequency of nausea was found between the two groups (P = 0.28). The sample sizes used allow an 80% power for detecting a clinically significant difference of 4% adverse effects in one group and 10% in the other group when testing at a significance level of 5%. CONCLUSIONS: Warming of fluorescein dye does not significantly alter the incidence of nausea reported with FA.

Female↗
PubMed2001

Retinal vascular alterations associated with dome-shaped and mushroom-shaped choroidal melanomas.

PURPOSE: Retinal vascular abnormalities are associated with choroidal melanoma. Although tumor ischemia, resulting in soluble angiogenic factor production, is a proposed etiology of these abnormalities, other sources of ischemia may also contribute. Mushroom-shaped choroidal melanomas have increased loss of the overlying choriocapillaris and increased subretinal fluid when compared to dome-shaped tumors; factors that may result in outer retinal ischemia, angiogenic factor production and resultant retinal vascular abnormalities. The differing amounts of retinal vascular abnormalities overlying dome-shaped compared to mushroom-shaped melanomas were determined to evaluate this hypothesis. METHODS: Retinal vascular abnormalities observed on fluorescein angiograms of eyes with choroidal melanoma were compared to the tumor configuration and presence of subretinal fluid. RESULTS: 23 eyes of 22 patients were included in the study. Retinal vascular abnormalities observed included dilated capillaries, telangiectatic capillaries, capillary nonperfusion, microaneurysms, neovascularization, lipid exudation and late staining of dye within the retina. Retinal vascular abnormalities were present in 4 of 14 eyes with dome-shaped tumors (29%) and in 8 of 9 eyes with mushroom-shaped tumors (89%). (Fisher's Exact Test, p = 0.009). Retinal vascular abnormalities were present in 2 of 10 eyes without subretinal fluid (20%) and in 10 of 13 eyes with subretinal fluid (77%). (Fisher's Exact Test, p = 0.012). CONCLUSIONS: Retinal vascular abnormalities are associated with mushroom-shaped choroidal melanomas more commonly than dome-shaped tumors. Outer retinal ischemia may result from choriocapillaris loss or the presence of subretinal fluid, contributing to soluble angiogenic factor production and resultant retinal vascular abnormalities in these eyes. SUMMARY STATEMENT: Retinal vascular abnormalities are associated with mushroom-shaped choroidal melanomas more commonly than dome-shaped tumors. These retinal vascular abnormalities may be related to an increase in outer retinal ischemia associated with mushroom-shaped tumors.

Adult↗
PubMed1999

Photocoagulation of iris nevus to control recurrent hyphema.

PURPOSE: To report a case of recurrent hyphema caused by an iris nevus that was successfully treated with photocoagulation. METHOD: Case report. In a 30-year-old woman with recurrent hyphema secondary to an iris nevus, photocoagulation was applied to the iris nevus. RESULTS: Before photocoagulation of the iris nevus, the patient had increasing frequency of hyphema episodes. After treatment, no hyphema episodes occurred during 13 months of observation. CONCLUSION: Photocoagulation of the surface of an iris nevus may prevent recurrent hyphema.

Adult↗
PubMed1999

Corneal topographic changes after extraocular muscle surgery.

PURPOSE: Changes in refractive error have been reported after strabismus surgery. The influence of extraocular muscle tension on corneal topography is thought to be an important mechanism contributing to this alteration. This study investigates topographic changes after strabismus surgery in human beings. METHODS: The corneal topography of 63 eyes of 43 patients who underwent either strabismus or optic nerve sheath fenestration (ONSF) surgery was measured before and after operation. The ONSF surgery involved removing and reattaching the medial rectus muscle, thus acting as a control for the strabismus procedures. Corneal power was measured centrally and at 1.5 and 3.0 mm in 8 meridians. Analysis of variance was performed to compare the difference in preoperative and post-operative corneal power for all procedures and comparing recessions, resections, combined recession and resection, and ONSF as grouped procedures. RESULTS: All groups showed a significant change in preoperative to postoperative corneal power (P< .01). A significant change was seen between all grouped procedures except when the resection was compared with ONSF and compared with recession. CONCLUSIONS: Change in the tension of 1 muscle does not produce a change in the adjacent quadrant as much as it produces a significant change in the entire corneal surface, which illustrates the interaction and interdependence all corneal positions have with respect to each other.

Adolescent↗
PubMed1998

An intravitreal sustained-release triamcinolone and 5-fluorouracil codrug in the treatment of experimental proliferative vitreoretinopathy.

OBJECTIVE: To determine the efficacy and pharmacokinetics of an intravitreal sustained-release triamcinolone acetonide and 5-fluorouracil (TA/5-FU) codrug in the treatment of experimental proliferative vitreoretinopathy (PVR). METHODS: The therapeutic efficacy of the TA/5-FU codrug was determined in a rabbit model that simulates human PVR. Intravitreal levels of triamcinolone and 5-fluorouracil were measured at different time points and drug release in vitro was tested. Toxic effects were evaluatedby electroretinograpy, clinical examination, and light microscopy. RESULTS: Both the severity of PVR grade and the percentage of eyes with moderate or worse tractional detachment were significantly less in eyes treated with the codrug. The therapeutic effect of the intravitreal codrug was paralleled by sustained intravitreal levels of triamcinolone and 5-fluorouracil. There were no drug-related toxic effects evident on clinical or histopathologic examination of eyes containing the TA/5-FU codrug. CONCLUSIONS: The intravitreal sustained-release TA/5-FU codrug effectively inhibits the progression of PVR in a rabbit model that closely resembles PVR in humans. The TA/5-FU codrug may simultaneously target different components of the wound-healing response.

Animals↗
PubMed1997

Sustained closure of surgically repaired macular holes after retinal detachment with submacular fluid.

PURPOSE: To examine the behavior of surgically repaired macular holes when subsequent retinal detachment with submacular fluid develops and to correlate these observations with current theories of macular hole formation and closure. METHODS: We reviewed the medical records of four patients who underwent successful surgical closure of macular holes and subsequently developed rhegmatogenous retinal detachment with macular involvement. RESULTS: No reopening of the original macular hole occurred in any of the four patients. No focal macular attachment was seen that would suggest firm adherence of the macular hole edges to the underlying retinal pigment epithelium. CONCLUSIONS: When retinal detachment with submacular fluid develops in patients with a successfully closed macular hole, sustained closure of the macular dehiscence is typically seen. These findings support reapproximation of the hole edges with an associated retinal wound healing response as the mechanism of hole closure.

Aged↗
PubMed1996

Condensation on polymethylmethacrylate, acrylic polymer, and silicone intraocular lenses after fluid-air exchange in rabbits.

PURPOSE: Condensation occurs rapidly on silicone intraocular lenses (IOLs) after vitrectomy and fluid-air exchange in the presence of a posterior capsulotomy, severely limiting the retinal view. Foldable IOLs made of an acrylic polymer are now available. The authors compare the condensation and subsequent retinal view degradation after vitrectomy and fluid-air exchange in rabbit eyes implanted with polymethylmethacrylate (PMMA), soft acrylic polymer (ACRYSOF), and silicone IOLs. METHODS: Thirty rabbits underwent bilateral lens removal. Twenty PMMA, 20 acrylic polymer, and 20 silicone IOLs were implanted into the capsular bag. After three-port vitrectomy, eyes were randomly assigned to undergo a posterior capsulotomy or to an intact posterior capsule. Fluid-air exchange was performed, and the amount of condensation on the IOL surface and resultant retinal view was graded. Surgical maneuvers then were performed to decrease the condensation. These maneuvers included wiping the IOL surface with a soft-tipped cannula and coating it with viscoelastic. RESULTS: No condensation occurred on IOLs in eyes with an intact posterior capsule. Significantly more condensation occurred on IOLs in eyes with a capsulotomy, regardless of IOL type (P < 0.014). Wiping the condensation resulted in significantly less condensation and improved retinal view on the PMMA and acrylic IOLs when compared with the silicone IOLs (P < 0.024). Condensation was eliminated on all three IOL types after viscoelastic was applied. However, increased distortion of the retinal view was induced by the viscoelastic on the silicone IOL as compared with the other IOLs. CONCLUSIONS: Condensation and subsequent retinal image degradation occurs uniformly after vitrectomy, posterior capsulotomy, and fluid-air exchange in eyes with PMMA, acrylic, and silicone IOLs. Because the condensation can be eliminated most easily on acrylic IOLs compared with silicone IOLs, when foldable IOL techniques are used it is likely that an acrylic polymer IOL would be advantageous for those patients at risk for future vitreous procedures requiring fluid-air exchange.

Animals↗
PubMed1996

Intravitreal delivery of ciprofloxacin.

The objective of this work was to evaluate various methods of sustained delivery to achieve therapeutic intravitreal levels of ciprofloxacin as a potential therapy for endophthalmitis. Two types of intravitreal bioerodible sustained release devices of ciprofloxacin were evaluated in vitro. The most promising device was evaluated in rabbits and results compared with subconjunctival injections of a ciprofloxacin suspension. Subconjunctival injections failed to deliver therapeutic concentrations of ciprofloxacin into either the aqueous or vitreous. In vivo evaluation of the intravitreal device consistently delivered ciprofloxacin at levels above 1 ug/ml for up to four weeks. No retinal activity was noted by clinical examination or by electroretinogram. Intravitreal implantation of bioerodible ciprofloxacin devices can maintain vitreous concentrations above 1 ug/ml, more than the MIC90 of most organisms associated with endophthalmitis. Implantation of these devices appears to be well tolerated and may represent a viable treatment for this disease. Further studies in endophthalmitis models are needed to evaluate device efficacy.

Animals↗
PubMed1996

Sustained release intravitreal dexamethasone.

Sustained intravitreal levels of dexamethasone may be useful in the treatment of proliferative vitreoretinopathy (PVR). The preparation and evaluation of an implantable system for intravitreal sustained release of dexamethasone is described. Pellets of dexamethasone were coated in biocompatible, nonerodible polymers and the release rate tested in vitro. Devices were then implanted in the rabbit vitreous and the in vivo release rate and corresponding steady state vitreous concentration determined. Toxicity was also evaluated by histopathology and electrographic examination. Devices released dexamethasone at approximately 1 ug/hr in vitro and 1.5 ug/hr in vivo. When implanted into the vitreous intravitreal concentrations of approximately 2.5 +/- 1.2 ug/hr were maintained for over 3 months. Devices were well tolerated with no evidence of inflammation or retinal abnormalities.

Animals↗
PubMed1993

Clearance and distribution of ciprofloxacin after intravitreal injection.

This study was designed to determine the drug concentration and clearance after intravitreal injection of ciprofloxacin. Ciprofloxacin (100 micrograms/0.1 cc) was injected into the vitreous of normal eyes and into eyes that had undergone lensectomy and vitrectomy. Drug concentration was determined using high-pressure liquid chromatography analysis 0.5, 2, 4, and 12 hours after injection. In normal eyes, the elimination half life was 2.2 hours with a distribution volume of 1.2 ml. In aphakic vitrectomized eyes, the half life was 1 hour and the distribution volume was 1.4 ml. The majority of the drug appears to leave via a transretinal route, but clearance was not inhibited by probenecid. Because of the relatively short half life, intravitreal administration of ciprofloxacin for the treatment of endophthalmitis would provide only short-term therapy and would need to be supplemented by other forms of treatment.

Animals↗
PubMed1990

Scanning electron microscopy of corneal incisions using steel, diamond, and sapphire blades.

In order to compare the wound morphology they produce, we used steel (Myocure), diamond (CILCO DK 121), and sapphire (Katena K2-6500) blades, to make parallel linear incisions, 500 microns deep, in 12 fresh enucleated porcine eyes. There was no discernible difference among the blades in terms of either the morphology of the collagen lamellae of the sides or the depth of the incisions produced. The major differences in the cuts produced were attributable primarily to the differences in the footplates.

Animals↗