Search PubMed⌕ Search

Biomedical subjects

T W Olsen

Publications and source records attributed to T W Olsen.

At least 19 recordsLinked to original sources
PubMed2001

Treatment of submacular hemorrhage with low-dose intravitreal tissue plasminogen activator injection and pneumatic displacement.

OBJECTIVE: To investigate the safety and efficacy of low-dose intravitreal tissue plasminogen activator (tPA) and an expansile gas bubble in displacing submacular hemorrhage in patients with age-related macular degeneration (ARMD). PATIENTS AND METHODS: We reviewed retrospectively the medical records of 14 consecutive patients with ARMD from 1 academic center who received low-dose intravitreal tPA (18-50 microg) and expansile gas (0.3-0.4 mL of perfluoropropane) for thrombolysis and displacement of submacular hemorrhage. After the procedure, patients maintained face-down positioning for 1 to 3 days. MAIN OUTCOME MEASURES: Displacement of blood from the fovea, early and final visual acuity, and toxicity of tPA. RESULTS: Submacular blood was completely displaced from the fovea in 10 (71%) of the 14 patients and partially displaced in 3 (21%). In 1 patient, no displacement occurred. Early (<2 months) postoperative visual acuity improved by 2 or more lines in 8 patients (57%). With a mean follow-up of 7.7 months, 2 (15%) of 13 patients maintained 2 or more lines of improvement and 69% (9 patients) maintained preoperative visual acuity. No clinical evidence of retinal toxicity was seen at this low-dose of tPA. CONCLUSIONS: Doses of intravitreal tPA ranging from 18 to 50 microg and an expansile gas bubble are safe and effective in displacing submacular hemorrhage in patients with ARMD. Final visual acuity was limited by the underlying presence of end-stage ARMD.

Aged↗
PubMed2000

Evidence for contribution of tripartite hemolysin BL, phosphatidylcholine-preferring phospholipase C, and collagenase to virulence of Bacillus cereus endophthalmitis.

Bacillus cereus causes a highly fulminant endophthalmitis which usually results in blindness. We previously concluded that hemolysin BL (HBL), a tripartite necrotizing pore-forming toxin, is a probable endophthalmitis virulence factor because it is highly toxic to retinal tissue in vitro and in vivo. We also determined that B. cereus produces additional retinal toxins that might contribute to virulence. Here we fractionated crude B. cereus culture supernatant by anion-exchange chromatography and found that in vitro retinal toxicity was also associated with phosphatidylcholine-preferring phospholipase C (PC-PLC). The pure enzyme also caused retinal necrosis in vivo. We showed that phosphatidylinositol-specific PLC and sphingomyelinase were nontoxic and that two hemolysins, cereolysin O and a novel hemolysin designated hemolysin IV, were marginally toxic in vitro. The histopathology of experimental septic endophthalmitis in rabbits mimicked the pathology produced by pure HBL, and both HBL and PC-PLC were detected at toxic concentrations in infected vitreous fluid. Bacterial cells were first seen associated with the posterior margin of the lens and eventually were located throughout the lens cortex. Detection of collagenase in the vitreous humor suggested that infiltration was facilitated by the breakdown of the protective collagen lens capsule by that enzyme. This work supports our conclusion that HBL contributes to B. cereus virulence and implicates PC-PLC and collagenase as additional virulence factors.

Amino Acid Sequence↗
PubMed1999

Idiopathic reactive hyperplasia of the retinal pigment epithelium.

OBJECTIVES: To present and discuss 2 patients with acquired peripapillary pigmented lesions. METHODS: We reviewed the patients' clinical records and histopathologic findings. RESULTS: The first patient was diagnosed with a pigmented papillary lesion that was followed up for 38 years. The second patient was a child with neurofibromatosis type 1 who developed a pigmented peripapillary lesion following excision of an optic nerve glioma. Histologic findings in both cases demonstrated hyperplasia of the retinal pigment epithelium with associated findings. CONCLUSIONS: The lesions presented an idiopathic reactive hyperplasia of the retinal pigment epithelium. The clinical and histopathologic findings resemble findings reported with the combined hamartoma. We suggest that such lesions are reactive in nature, rather than hamartomatous.

Child, Preschool↗
PubMed1998

Human sclera: thickness and surface area.

PURPOSE: To assess the mean thickness and surface area of human sclera. METHODS: Fifty-five formalin-fixed eye bank eyes were hemisected from anterior to posterior. Cross-sectional slides were taken to include a millimeter scale ruler in each photograph. Slide photographs were projected and the scleral silhouette sketched. Mean scleral thickness measurements with standard deviation were obtained. Twenty-five human eye bank eyes were used to determine total scleral surface area by either a computerized tracing method (17 globes) or volumetric calculations (eight globes) using fluid displacement. RESULTS: Mean scleral thickness +/- SD was 0.53 +/- 0.14 mm at the corneoscleral limbus, significantly decreasing to 0.39 +/- 0.17 mm near the equator, and increasing to 0.9 to 1.0 mm near the optic nerve. The mean total scleral surface area by surface area computerized tracings was 16.3 +/- 1.8 cm2 and, by the volume displacement method, was 17.0 +/- 1.5 cm2. CONCLUSIONS: Scleral thickness and surface area measurements from cadaver eyes are important for ophthalmic surgeons and have implications for transscleral diffusion.

Body Surface Area↗
PubMed1998

Macular hole surgery using thrombin-activated fibrinogen and selective removal of the internal limiting membrane.

PURPOSE: To evaluate a tissue sealant (autologous cryoprecipitate activated with bovine thrombin) as an adjuvant in macular hole surgery. METHODS: Sixty-nine patients with stage 2, 3, or 4 full-thickness macular hole were enrolled consecutively in a prospective pilot study. Anatomic closure of the macular holes with a single operation was the primary outcome. Fifty-eight patients had pre- and postoperative standardized measurements including best refracted visual acuity, reading speed, and contrast sensitivity. Group A patients (45) had primary macular holes; Group B patients (13) had recurrent macular holes or macular holes with "other" retinal pathology. Surgical technique was standardized and membrane dissections were optional. RESULTS: The anatomic closure rate was 80% with a minimum of 6 months follow-up. Mean improvement in visual acuity for Group A (2.9+/-0.4 lines) was significantly better than for Group B (0.8+/-0.5 lines; P = 0.008). Eyes that underwent internal limiting membrane (ILM) dissections had an anatomic closure rate of 96% (23/24), compared with 71% (32/45) in "non-ILM" cases (P = 0.034). Adverse reactions included sterile hypopyon (10%), intraretinal hemorrhage (9%), pigmentary hyperplasia (3%), and retinal detachment (3%). CONCLUSION: Tissue sealants should be evaluated as an adjuvant in macular hole surgery in a randomized clinical trial. Inflammatory reactions may occur in some patients. Internal limiting membrane dissection may improve anatomic closure rates without adversely affecting the visual acuity.

Adult↗
PubMed1997

A model for light toxicity of cultured human retinal pigment epithelium.

BACKGROUND: The effect of visible light on human retinal pigment epithelial (HRPE) cells has not been characterized under conditions that provide strict thermal control. METHODS: HRPE cells were isolated and grown to confluence. Cells were exposed to light in an incubator in which the cell temperature was controlled in response to a temperature sensor maintained in the tissue culture medium. Cells were exposed: (A) for 24, 36, and 48 h; and using a 24-h exposure followed by 24 h darkness; (B) at varying intensities of light using neutral density filters; (C) under a yellow filter; and (D) with a 12-h on-off cyclic light. RESULTS: (A) Light exposure of 36 and 48 h resulted in significant cytotoxicity, while the initial 24-h exposure did not induce subsequent cytotoxicity. (B) Light irradiance levels from 43 to 54 mW/cm2 were required to demonstrate cytotoxicity. (C) Use of a yellow filter did not eliminate the observed cytotoxicity. (D) Cyclic exposure did not result in significant cytotoxicity. CONCLUSION: This study establishes a model and basic parameters of light toxicity to HRPE cells in vitro using strict temperature control that may be used to evaluate photochemical injury to HRPE cells.

Adolescent↗
PubMed1997

A system for classifying mechanical injuries of the eye (globe). The Ocular Trauma Classification Group.

PURPOSE: To develop a classification system for mechanical injuries of the eye. METHODS: The Ocular Trauma Classification Group, a committee of 13 ophthalmologists from seven separate institutions, was organized to discuss the standardization of ocular trauma classification. To develop the classification system, the group reviewed trauma classification systems in ophthalmology and general medicine and, in detail, reports on the characteristics and outcomes of eye trauma, then established a classification system based on standard terminology and features of eye injuries at initial examination that have demonstrated prognostic significance. RESULTS: This system classifies both open-globe and closed-globe injuries according to four separate variables: type of injury, based on the mechanism of injury; grade of injury, defined by visual acuity in the injured eye at initial examination; pupil, defined as the presence or absence of a relative afferent pupillary defect in the injured eye; and zone of injury, based on the anteroposterior extent of the injury. This system is designed to be used by ophthalmologists and nonophthalmologists who care for patients or conduct research on ocular injuries. An ocular injury is classified during the initial examination or at the time of the primary surgical intervention and does not require extraordinary testing. CONCLUSIONS: This classification system will categorize ocular injuries at the time of initial examination. It is designed to promote the use of standard terminology and assessment, with applications to clinical management and research stud ies regarding eye injuries.

Adult↗
PubMed1997

Visual acuity in children with colobomatous defects.

Examining a child with a colobomatous defect can be challenging. The most important predictor of visual outcome is identification of normal foveal anatomy. The clinician should first evaluate the child for the associated systemic conditions. The next step is to identify the presence of normal foveal structures in the involved eye(s). If present, a trial of amblyopia treatment should be initiated. Anisometropic amblyopia is common and should be addressed. Retinal detachments are common and add uncertainty to predicting visual acuity.

Child↗
PubMed1996

Postoperative hypopyon after intravitreal bovine thrombin for macular hole surgery.

PURPOSE: We used intravitreal autologous fibrinogen with bovine thrombin for the surgical closure of macular holes in 60 cases. METHODS: Pars plana vitrectomy with separation of the posterior cortical vitreous was performed after air/fluid exchange. One to two drops each of autologous fibrinogen and bovine thrombin (20 to 80 U) were instilled in each patient. RESULTS: Five (8%) of 60 patients developed a hypopyon without unusual pain on the first postoperative day. Inflammation responded to frequent topical corticosteroids within 48 to 72 hours. CONCLUSION: Postvitrectomy hypopyon after the use of bovine thrombin may represent an immune reaction that must be differentiated from endophthalmitis. We recommend careful observation and frequent topical corticosteroids.

Adult↗
PubMed1996

Subfoveal choroidal neovascularization in punctate inner choroidopathy. Surgical management and pathologic findings.

PURPOSES: To evaluate submacular surgery for the management of subfoveal choroidal neovascularization in punctate inner choroidopathy, to describe the histopathology and ultrastructure of the excised subretinal tissue, and to propose a staging system that characterizes the development of choroidal neovascularization with associated subretinal fibrosis. METHODS: The authors reviewed the records of five patients (6 eyes) with punctate inner choroidopathy who underwent submacular surgery for subfoveal choroidal neovascularization. Surgical specimens were examined using light and transmission electron microscopy. RESULTS: Visual improvement was noted postoperatively in all six eyes, with follow-up ranging from 8 to 36 months (median, 14 months). Recurrences (6 in 4 eyes) were common. Five of the six recurrences required additional procedures: three were managed surgically, two with laser photocoagulation, and one with observation. "Bridging" of separate foci of choroidal neovascularization resulted in stellate or "dumbbell-shaped" areas of subretinal fibrosis in four of six eyes. Histopathologic evaluation of the excised tissue showed endothelial-lined vascular channels, retinal pigment epithelium, lymphocytes, plasma cells, fibrocytes, collagen fragments, and rarely, outer retinal elements. CONCLUSIONS: Subfoveal choroidal neovascularization in punctate inner choroidopathy may be managed with submacular surgery. Recurrences are common and may result in substantial loss of vision. Choroidal neovascular membranes with an accompanying fibrotic reaction are responsible for the stellate or dumbbell-shaped areas of subretinal fibrosis. No beneficial effect was demonstrated using corticosteroid treatment of the choroidal neovascularization.

Adult↗
PubMed1996

Misoprostol with cyclosporin A prolongs corneal allograft survival in an animal model.

Cyclosporin A (CSA) has been shown to prolong corneal allograft survival in a variety of animal models. Misoprostol is a prostaglandin E1 analogue with oral bioavailability and immunosuppressive properties. Misoprostol and CSA are synergistic immunosuppressants in vitro. In the present study, we evaluated the effect of adding misoprostol to a subtherapeutic dose of CSA in the orthotopic allogeneic rat penetrating keratoplasty model. Seventy inbred Lewis rats were recipients of orthotopic corneal allografts from Brown-Norway donors. Ten Lewis rats received orthotopic syngeneic grafts (Lew to Lew). Two separate experiments with 40 animals per trial were performed. In each trial, the rats were divided equally into four groups. Trial A: allogeneic control (A1), syngeneic control (A2), CSA at 10 mg/kg/d (A3), and CSA at 15 mg/kg/d (A4). Trial B: allogeneic control (B1), CSA alone at 7.5 mg/kg/d (B2), misoprostol alone at 1 mg/kg/d (B3), and CSA with misoprostol at 7.5 and 1 mg/kg/d, respectively (B4). Syngeneic control A2 as well as group A4 remained clear through postoperative day 22. The allogeneic control groups A1 and B1, plus treatment groups B2 and B3, rejected their grafts by postoperative day 12. Groups A3 and B4 demonstrated a delay in allograft rejection that continued to be statistically significant through the 12th postoperative day (p < 0.001). We conclude that the addition of systemic misoprostol to CSA can effectively prolong corneal allograft survival in the orthotopic allogeneic rat penetrating keratoplasty model.

Animals↗
PubMed1995

Human scleral permeability. Effects of age, cryotherapy, transscleral diode laser, and surgical thinning.

PURPOSE: To determine the in vitro permeability of human sclera to compounds varying in molecular weight. To evaluate the effects of age, cryotherapy, transscleral diode laser, and surgical thinning on scleral permeability. METHODS: Scleral tissue from 97 human eye bank eyes was tested individually in a two-chamber Ussing apparatus with the following hydrophilic radiolabeled compounds on one side of the chamber: 5-fluorouracil, sucrose, dexamethasone, methotrexate, inulin, and three separate dextran polymers (MWt = 10,000, 40,000, and 70,000). Scleral hydration levels were obtained on 20 more scleral specimens. Additional groups of scleral specimens were treated with either a cryotherapy probe, a transscleral diode laser retinopexy probe, or partial thickness lamellar dissection, and specimens were mounted in the Ussing chambers for testing. Scleral tissue was digested to measure the amount of radioactivity present. Scleral sections were examined with electron microscopy. RESULTS: Scleral hydration was maintained during the perfusion. The mean scleral permeability (cm/second x 10(-6) +/- SD) was established for each of the above compounds. Age, cryotherapy, or diode laser treatment did not alter permeability or ultrastructure of the sclera. Surgical thinning significantly increased the scleral permeability to dexamethasone (P = 0.011) and methotrexate (P = 0.037). CONCLUSION: This study establishes baseline human scleral permeability to a series of hydrophilic compounds with various molecular weights. Age, cryotherapy, and diode laser treatment do not alter the permeability or ultrastructure of the sclera, whereas surgical thinning significantly increases permeability.

Adolescent↗
PubMed1994

Linear endotheliitis.

We treated six eyes of five patients with linear endotheliitis. This entity appears clinically as a line of keratic precipitates on the corneal endothelium that progresses centrally and is accompanied by peripheral stromal and epithelial edema. All five patients had ocular pain, redness, and photophobia. One eye had an episode of a dendritic lesion typical of herpes simplex. Two eyes had a history of cataract extraction before developing linear endotheliitis. We treated all patients aggressively with a combination of corticosteroids and antiviral agents. Complete resolution of inflammation and edema occurred in all cases. Four patients required the use of oral acyclovir to control the inflammation and prevent recurrence of the disease. Linear endothelitis is a distinct form of endotheliitis that may be associated with herpes simplex virus, and treatment included corticosteroid and antiviral therapy.

Acyclovir↗
PubMed1994

Rapamycin inhibits corneal allograft rejection and neovascularization.

OBJECTIVE: To investigate the immunosuppressive effect of rapamycin in prolonging allograft survival in the rat model of orthotopic allogeneic penetrating keratoplasty. DESIGN: Thirty inbred Lewis rats received corneal allografts from Brown Norway donors. Animals were divided into two rapamycin treatment groups and one allogeneic control group. RESULTS: By the second week after surgery, all of the control animals had experienced allograft failure due to allograft rejection. However, allografts in seven of 10 animals in the low-dose treatment group and allografts in seven of nine animals in the high-dose treatment group remained clear. In addition, corneal neovascularization was markedly reduced in the treated animals. CONCLUSIONS: The systemic administration of rapamycin prolongs corneal allograft survival and significantly inhibits the neovascular component of rejection in the rat model of orthotopic allogeneic penetrating keratoplasty.

Animals↗