Biomedical subjects
L A Mawn
Publications and source records attributed to L A Mawn.
Unilateral follicular conjunctivitis with retained hair and pseudomonal infection.
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Proliferation of human fibroblasts in vitro after exposure to orbital implants.
BACKGROUND: Porous orbital implants allow fibrovascular ingrowth and integration with the extraocular muscles. The available implants have different structural characteristics, which may influence orbital response. We studied the proliferation of orbital fibroblasts in vitro after exposure to four different orbital implants. METHODS: Four orbital implant biomaterials were studied: hydroxyapatite (Bio-Eye), synthetic hydroxyapatite, porous polyethylene (Medpor) (pore sizes 150 microm and 400 microm) and aluminium oxide (Bioceramic implant). Human fibroblasts obtained from orbital fat at the time of elective blepharoplasty were cultured and then exposed to the individual implants. Cell growth was assessed with immunocytochemical analysis using bromodeoxyuridine, a thymidine analogue. After DNA denaturation, the cells were washed, incubated with secondary antibody and visualized. RESULTS: The fibroblasts growing on the Bio-Eye, synthetic hydroxyapatite, and 150-microm and 400-microm Medpor implants all had debris associated with them. The Bioceramic implant was free of this debris. The Bioceramic implant and the 150-microm Medpor implant had the greatest number of fibroblasts on the coverslips. INTERPRETATION: The proliferation of fibroblasts, as determined by visualization of actively dividing cells with bromodeoxyuridine, differed on the various implants studied. The lack of debris associated with the Bioceramic implant may be related to the crystalline structure of the implant.
Hydroxyapatite implant wrapping materials: analysis of fibrovascular ingrowth in an animal model.
PURPOSE: To compare the influence of seven currently available spherical orbital implant wraps on host fibrovascularization of a hydroxyapatite (HA) orbital implant. METHODS: Five groups of 3 (15 total) adult male New Zealand albino rabbits underwent enucleation with placement of a 12-mm HA implant wrapped in high-porosity expanded polytetrafluoroethylene (e-PTFE), processed bovine pericardium, or processed human pericardium, sclera, or fascia lata. Magnetic resonance imaging before and after the intravenous administration of gadolinium-diethylenetriamine pentaacetic acid (DTPA, 0.1 mol/kg) was performed immediately before exenteration. Five rabbits (one with each of the different implant wraps) were killed at 4, 8, and 12 weeks, and the operated socket was exenterated. Histopathologic sections of the implants were then compared with the results of our previous study using polyglactin 910 mesh and autologous sclera as HA orbital implant wraps. RESULTS: Complete fibrovascularization of all the implants occurred by 12 weeks; however, HA implants wrapped with sclera, polyglactin mesh, and e-PTFE appeared to undergo more rapid fibrovascularization than spheres wrapped with other materials. CONCLUSIONS: Although all of the implant wraps studied may be suitable substitutes for donor sclera, we prefer polyglactin mesh because it is readily available, inexpensive, and without risk of transmissible diseases.
The bioceramic orbital implant: a new generation of porous implants.
PURPOSE: The authors describe a new generation of porous orbital implant made of aluminum oxide (Al2O3) and compare it with the hydroxyapatite orbital implants (Bio-Eye and FCI hydroxyapatite). METHODS: The authors examined the new implant macroscopically, with chemical analysis and microscopically with scanning electron microscopy. Animal implantation studies were performed using six adult male New Zealand albino rabbits. Implant vascularization was evaluated by means of magnetic resonance imaging and histopathologic sectioning. RESULTS: The Bioceramic orbital implant was found to have very uniform pore structure with an average pore size of 500 microm. The implant was 99.9% aluminum oxide on x-ray diffraction. Magnetic resonance imaging in vivo vascularization studies demonstrated enhancement of the implant to its center by 4 weeks after implantation in the rabbit. Histopathologically, fibrovascularization occurred uniformly throughout the implant and was noted by 4 weeks. CONCLUSIONS: The Bioceramic orbital implant represents a new porous orbital implant that has a very regular and extensive interconnected pore system, is as biocompatible as hydroxyapatite, is easy to manufacture, structurally strong, and free of contaminants. It is manufactured with no disruption to marine life ecosystems as may occur in the harvesting of coral for other orbital implants. It is less expensive than currently available hydroxyapatite implants and was approved by the U.S. Food and Drug Administration in April 2000.
Giant cell angiofibroma of the eyelids: an unusual presentation of tuberous sclerosis.
The authors describe a patient with a history of mental retardation and seizures who presented with unusually large edematous, pedunculated eyelid lesions of unknown etiology. The histopathology revealed features consistent with giant cell angiofibroma, a variant of the angiofibromas commonly seen in tuberous sclerosis.
Spindle-cell lipoma of the preseptal eyelid.
An 82-year-old woman had experienced progressive enlargement of a long-standing left upper lid mass for 3 weeks. The superior visual field was compromised secondary to mechanical ptosis from this lid lesion. Computed tomography showed a large lid mass with a low density signal, similar to intraorbital fat. The tumor was completely excised. Histopathologic examination showed an encapsulated tumor composed of mature adipose tissue interspersed with fibrovascular septa containing spindle-cells, confirming a diagnosis of spindle-cell lipoma.
Ruptured globe during orbital decompression surgery.
A 74-year-old patient sought treatment for visual obscuration and clinically had signs of Graves orbitopathy. Past medical history was unremarkable except for the use of antihypertensive medication. During the hospital admission, a fluorescent treponemal antibody absorption test was reactive, indicating infection with syphilis at some time in the past. Visual deterioration despite oral corticosteroid therapy prompted orbital decompression. At the time of surgery, she sustained a globe rupture. Presumably, syphilitic scleritis was responsible, in part, for scleral thinning and weakening, predisposing her to this complication. To the authors' knowledge, globe rupture has not been previously reported during orbital decompression.
Scanning electron microscopic examination of porous orbital implants.
OBJECTIVE: To compare the structural makeup of five porous orbital implants: two made of coralline hydroxyapatite (Bio-Eye and Chinese implant), one of synthetic hydroxyapatite (FCI), one of porous polyethylene (Medpor) and one of alumina. The Bio-Eye, Medpor and alumina implants are currently available in Canada. OUTCOME MEASURES: Pore size, pore interconnectivity and microcrystalline architecture. RESULTS: The Bio-Eye had multiple interconnected pores ranging from 300 microns to 700 microns in width; higher-power views showed coarse-appearing crystals approximately 2 microns wide. The FCI implant showed similar interconnectivity of the pores but fewer pores, which were about 300 microns to 500 microns in size. Higher-power views showed hexagonal crystals about 1 micron to 5 microns in size. The Chinese hydroxyapatite implant had multiple interconnected pores ranging from 200 microns to 700 microns in size. The crystals were similar in appearance to those of the Bio-Eye but were smaller and more granular. The 150-micron pore size Medpor implant had irregularly shaped pores ranging from 100 microns to 500 microns in size. The 400-micron pore size implant had pores that looked more like channels that coalesced; the pores and channels ranged in size from 125 microns to 1000 microns. In both cases higher-power views showed a woven texture. In the alumina implant the pores were well connected and evenly distributed and were approximately 500 microns in size. On high-power studies the implant showed a cobblestone-like pattern of crystals approximately 4 microns to 5 microns wide. CONCLUSIONS: There are notable differences in pore size, pore interconnectivity and microcrystalline architecture between the implants studied. These features may be important in the overall biocompatibility of the implant.
Cavernous hemangiomas of the orbital apex with intracranial extension.
Cavernous hemangiomas are benign vascular tumors that usually present as unilateral, intraconal mass lesions in middle-aged women. They may on occasion extend to the orbital apex or have intracranial extension. The authors present three patients with deep apical hemangiomas, two of whom had intracranial extension to the cavernous sinus area.
Dysmorphophobia: a distorted perception of one's self-appearance.
Patients with dysmorphophobia are preoccupied with an imagined or grossly exaggerated defect of appearance. These patients may seek cosmetic surgical procedures to alter their perceived abnormal appearance. Treatment of patients with dysmorphophobia has not been previously addressed in the ophthalmologic literature. The authors present three case reports and discuss the syndrome of dysmorphophobia.
Orbital color Doppler imaging in carotid occlusive disease.
OBJECTIVE: To define orbital circulation abnormalities identified by color Doppler imaging in patients with severe carotid occlusive disease. PATIENTS: Twenty-four patients referred to a hospital-based neuro-ophthalmology service with hemodynamically significant carotid occlusive disease (> 75% stenosis) were prospectively studied. Eight had signs of ocular ischemic syndrome; 12 of the 24 patients underwent endarterectomy. MAIN OUTCOME MEASURES: Peak systolic velocity of the central retinal, posterior ciliary, and ophthalmic artery and pulsatility indexes as determined by color Doppler imaging. METHODS: Color Doppler imaging was performed using a 7.5-MHz probe. Both eyes were studied in all patients and carotid duplex imaging was obtained. RESULTS: All patients with hemodynamically significant carotid occlusive disease had lower mean peak systolic velocities in the central retinal, posterior ciliary, and ophthalmic arteries and higher pulsatility indexes compared with normal control patients. Endarterectomy improved peak systolic velocities. Reversal of ophthalmic flow direction as a separate variable was unassociated with altered mean central retinal or posterior ciliary artery flow velocities. Patients with ocular ischemic syndrome may have similar orbital color Doppler imaging findings compared with patients with severe carotid occlusive disease without overt manifestations of chronic ocular ischemia. CONCLUSION: Orbital circulation is highly adaptable even when faced with severe compromise in proximal blood flow.
Trichotillomania.
PURPOSE: Trichotillomania is characterized by an irresistible urge to pull one's hair, and may involve the eyelashes or eyebrows. The authors present four cases of trichotillomania, and review the management of this unusual disorder. METHODS: The cases of four patients with trichotillomania were reviewed retrospectively. RESULTS: All four patients had characteristic areas of broken lashes along the lid in the absence of other signs of disease. Three of the four knew they were plucking the hair, yet could not control it. In the fourth, it was only after a lengthy observation period that she was discovered plucking. CONCLUSIONS: Trichotillomania has been infrequently reported in the ophthalmic literature. Management can be difficult. Many of these patients are aware of their behavior, but are unable to curtail it. Others may conceal or deny their habit. Psychiatric counseling may be of some benefit if patients are willing to undergo it.
Pseudomonas dacryoadenitis secondary to a lacrimal gland ductule stone.
Infectious dacryoadenitis is a rare condition. A case of Pseudomonas dacryoadenitis has not been reported previously. We treated a patient with Pseudomonas dacryoadenitis secondary to obstruction from a lacrimal gland ductule stone. Histologically, the calculus contained hairs.
Nucleolar organizer regions in iris nevi and melanomas.
The silver staining of nucleolar organizer region-associated proteins is an objective method that has been used to differentiate benign from malignant neoplasms. Recently this method was used to distinguish benign choroidal nevi from malignant choroidal melanomas. We studied 24 iris melanocytic lesions to assess the applicability of this technique for differentiating benign from neoplastic iris tumors. Masked observers determined the number of silver-stained nucleolar organizer region dots per cell for silver-stained specimens. Iris nevi contained a mean of 1.6 silver-stained nucleolar organizer region dots per cell, whereas iris (spindle A and B, spindle B, epithelioid, mixed cell) malignant melanomas contained a mean of at least 3.5 silver-stained nucleolar organizer region dots per cell (P less than .0001). All iris nevi demonstrated counts lower than 1.9, whereas all iris melanomas demonstrated counts greater than 2.8. Silver-stained nucleolar organizer region counts were also compared with the clinicopathologic variables of gender, age, and largest specimen dimension. Only the largest specimen dimension correlated with silver-stained nucleolar organizer region counts (P less than .0029). The silver-stained nucleolar organizer region method is a simple technique for differentiating iris nevi from iris melanomas. The silver-stained nucleolar organizer region technique may aid in the assessment and treatment of iris lesions by confirming the malignancy of biopsy specimens.
Congenital glaucoma and skeletal dysplasia.
We have observed congenital glaucoma in a patient with a skeletal dysplasia closely resembling Kniest syndrome. The clinical and radiographic features, along with the differential diagnosis of Kniest syndrome, are discussed. Review of the literature suggests a relationship between the pathophysiology of bone dysplasia and congenital glaucoma. Congenital glaucoma may be an additional ocular finding in Kniest syndrome.