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Biomedical subjects

B J Curtin

Publications and source records attributed to B J Curtin.

At least 19 recordsLinked to original sources

Scleral reinforcement in rabbits using synthetic graft materials.

Because of disappointing results using homologous collagen for scleral reinforcement in the treatment of pathologic myopia in humans, we undertook a series of experiments in rabbits to test the mechanical properties and long-term biocompatibility of three different synthetic graft materials. Grafts made from two of these materials, Gore-Tex Soft Tissue Patch (expanded polytetrafluoroethylene) and Miragel (poly[methyl acrylate-co-hydroxy-ethyl acrylate]), were easy to position about the globe. Both materials, however, were resistant to invasion by fibrovascular tissue. The third material, woven Dacron (polyethylene terephthalate), though more difficult to position, permitted extensive invasion of fibrovascular tissue, which made all parts of the graft firmly adherent to the globe. Our results indicate the long-term compatibility of all three of these materials when used as periscleral grafts in rabbits. However, our results also suggest that a woven material such as commercially available Dacron is a more suitable graft material for scleral reinforcement in humans than collagen, Miragel, or Gore-Tex.

Animals

Adult myopia.

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Adult

Pathologic myopia.

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Follow-Up Studies

Long-term results of scleral reinforcement surgery.

Of 40 scleral reinforcement operations for progressive severe myopia, 23 patients were followed up for a minimum of five years. Ten of 23 patients showed an essentially stable postoperative course (43%) while 13 (57%) had increases in myopia of -1.0 diopter or more. Among the operated on eyes, 17 of 23 eventually had some increase in myopia. Of the 20 eyes that had preoperative axial measurements, 18 (90%) had increases in axial diameter of 0.3 mm or more. There were complications in six of the 40 eyes, including anterior uveitis, motility disorders, and retinal detachment. Progression of posterior staphyloma formation or the onset of myopic fundus degeneration was observed in ten eyes. Two problems with this surgery are the limited scleral area reinforced by narrow grafts and the possible late involvement of graft collagen in the disease process of host sclera.

Adolescent

Scleral reinforcement: two case reports.

We report two cases of unilateral scleral reinforcement undergone for progressive pathologic myopia. Examination ten years after the operations showed the supportive effect of the scleral grafts. The effect, however, was localized and did not appear to block the overall progression of posterior staphyloma formation significantly.

Child

Scleral hyperplasia induced by heat.

We evaluated low-level heating as a stimulus to induce hyperplasia of normal rabbit sclera. Heat treatments were administered by placing an etched-element heater on bare sclera. Contact thermotherapy with a conductive device provided a favorable dose distribution for local scleral heating. A purely conductive heat source was selected to minimize intraocular heat penetration and to determine whether the scleral reaction was a primary thermal effect. Histologic examination of treated specimens showed thickening of normal rabbit sclera with preservation of the underlying normal ocular structures. Electron microscopic examination of treated sclera showed newly formed collagen fibrils adjacent to sclerocytes. These fibroblasts were activated, as manifested by well-developed rough-surfaced endoplasmic reticulum and hypertrophic Golgi complexes.

Animals

Normal and staphylomatous sclera of high myopia. An electron microscopic study.

The posterior sclera of three normal eyes and five staphylomatous, myopic eyes was examined by electron microscopy. The following notable differences were found in myopic sclera: a predominantly lamellar, collagen fiber bundle arrangement; a reduction in the diameter of the fibrils; a greater dispersion for the range of fibril diameters; an increase in unusual star-shaped fibrils on cross section; and a greater prevalence of fibril groups with uniform but extremely fine diameters. These findings essentially agree with those in other studies of the myopic sclera. The ultramicroscopic changes encountered inpathologic myopia are judged to be compatible with an abnormal proteoglycan composition of the interfibrillary substance in the ectatic sclera.

Adult

Physiologic vs pathologic myopia: genetics vs environment.

Physiologic myopia occurs as the result of a correlation failure of refraction components in the normal eye. Pathologic myopia is caused by excessive axial elongation that primarily involves the ora-equatorial area and the posterior pole. Peripheral fundus changes and posterior staphyloma formation are ophthalmoscopic evidences of this process. Heredity is the basic determinant of ocular refraction, but numerous agents produce both temporary and permanent myopias.

Animals

The posterior staphyloma of pathologic myopia.

A total of 250 myopic patients with posterior staphyloma affecting one or both eyes received a complete ocular examination including binocular indirect ophthalmoscopy, refraction, and axial length measurement. Ten types of staphyloma were noted; five primary and five compound. The primary staphyloma involved the posterior pole (Type I), macular area (Type II), peripapillary area (Type III), the fundus nasal to the disc (Type IV) and the area below the disc (Type V). Compound staphylomas consisted of combined primary staphylomas or distinctive and complex variations of a primary staphyloma, usually Type I. This type also was found to have the greatest prevalence of all ten types. Patients in this group had a 19% incidence of legal blindness with 34.5% of staphylomatous eyes having a vision of 20/200 or less. A remarkably wide range of refractions and axial lengths were found for each staphyloma type. These results indicate the importance of the staphyloma in the diagnosis and prognosis of pathologic myopia. It also offers an improved basis for genetic studies of this disease.

Adolescent

The Fuchs' spot: an ophthalmoscopic and fluorescein angiographic study.

A correlation of funduscopic and fluorescein angiographic findings in the Fuchs' spot of high myopia is presented. A variety of ophthalmoscopic changes indicate that both serous and hemorrhagic detachments of the retinal pigment epithelium and neurosensory retina are associated with this lesion. Fluorescein angiography, however, reveals subretinal reovascularization from the choroid as the basic underlying disease in most cases reviewed. Wide variations in the ophthalmoscopic appearance of the pigmented maculopathy of high myopia necessitate a more descriptive approach than that indicated by the term "Fuchs' spot." Fluorescein angiography becomes a necessity to delineate neovascular lesions as paracentral tufts may possibly be treated with laser photocoagulation to reduce progression.

Adult

Peripheral chorioretinal lesions and axial length of the myopic eye.

A study of the retinal periphery of 1,437 predominantly myopic eyes revealed a statistically significant association of four types of peripheral chorioretinal degenerations with increased axial length of the eye. These were white without pressure, pigmentary degeneration, pavingstone degeneration, and lattice degeneration. There was a tendency for both white without pressure and lattice degeneration jointly to affect eyes of individuals 19 years of age and younger. Increasing age was a significant factor in the incidence of pigmentary and pavingstone degenerations, whereas aging significantly reduced the prevalence of white without pressure.

Adult

Cataract extraction in pathological myopia.

Fifty-three cataract extractions in eyes with pathological myopia effected visual improvement in 47 eyes (89%). The median visual acuity increased from a preoperative level of 20/300 to 20/40 postoperatively. The incidence in this series of vitreous loss (1.9%) and retinal detachment (1.9%), are within the expected range of such complications. Four cases developed aphakic glaucoma which has necessitated continued therapy. All four had both enzyme zonulolysis and topical steroids, postoperatively. Other problems unique to surgery in these eyes are the missed diagnosis of nuclear cataract, possible dislocation of the lens, perforation of the sclera during retrobulbar injection, and rupture of the globe with vigorous digital massage.

Cataract Extraction

Lacquer crack lesions in pathologic myopia.

In evaluating the anatomic and functional status of 22 eyes of 14 patients demonstrating lacquer cracks, these lesions occurred in the eyes of young adults with posterior staphylomas and markedly increased axial lengths. Decreased visual acuity and altered visual fields were the rule; choroidal hemorrhage and focal chorioretinal atrophy were less frequently associated. Fluorescein angiography revealed early and late pseudofluorescence and late staining of the lesions. These clinical data suggest that lacquer cracks represent healed, mechanical breaks in the pigment epithelium-Bruch's membrane-choriocapillaris complex. The presence of these lesions implies a guarded prognosis for the retention of central vision.

Adolescent