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Biomedical subjects

H M Lambert

Publications and source records attributed to H M Lambert.

At least 37 records · Page 2Linked to original sources

Well-defined subfoveal choroidal neovascular membranes in age-related macular degeneration.

PURPOSE: The purpose of this study is to correlate the clinical, angiographic and ultrastructural features of well-defined subfoveal neovascular membranes. METHODS: Fundus photographs and fluorescein angiograms of five well-defined subfoveal neovascular membranes associated with age-related macular degeneration and exudative retinal detachment were obtained. The subfoveal membranes were surgically excised via the pars plana. The center and peripheral portions of each membrane were evaluated by transmission electron microscopy for cellular and extracellular constituents. RESULTS: Each subretinal neovascular membrane was composed of two distinct regions demonstrated by fluorescein angiography. The first component, the core, contained a brighter central area of hyperfluorescent leakage surrounded by a partial or complete cuff of elevated blocked choroidal fluorescence. Results of ultrastructural examination showed that the core was composed of a fibrovascular membrane characterized by endothelium-lined vascular channels with associated retinal pigment epithelium. The second region of the membrane, the rim, is previously unreported and is described in detail. It appeared as a minimally elevated, smooth, subretinal annular rim of hyperfluorescent staining that surrounded the core and was composed of fibrin, photoreceptor outer segments, and macrophages. CONCLUSIONS: Well-defined subfoveal neovascular membranes can be appreciated with fluorescein angiography and are composed of a central core of subfoveal choroidal neovascularization surrounded by a peripheral rim composed of fibrin, photoreceptor outer segments, and macrophages.

Aged↗

Ultrastructural features of surgically excised idiopathic subfoveal neovascular membranes.

The ultrastructural features of three surgically excised idiopathic subfoveal neovascular membranes were examined. Ultrastructural features of the cellular components in the membranes included retinal pigment epithelium, endothelial-lined vascular channels, photoreceptor cells, macrophages, myofibroblasts, glial cells, erythrocytes, and ghost erythrocytes. Extracellular constituents included 200-nm to 250-nm collagen fibrils, 100-nm collagen fibrils and fibrin. The findings in this study are consistent with previously reported findings of subfoveal neovascular membranes in age-related macular degeneration and the ocular histoplasmosis syndrome, with the exception of the presence of basal laminar deposit in membranes from age-related macular degeneration.

Adult↗

Surgical excision of subfoveal choroidal neovascular membranes.

The possibility for visual improvement after the treatment of subfoveal choroidal neovascular membranes with laser photocoagulation is poor. The surgical excision of these membranes in age-related macular degeneration, the presumed ocular histoplasmosis syndrome, idiopathic neovascularization, and myopia is the focus of current study. This review covers the rationale for considering a surgical approach, the techniques currently used to perform these procedures, and the clinical pathological correlation of the surgically excised specimens. Initial results of this surgery warrant a national randomized clinical trial of its efficacy.

Choroid↗

Vogt-Koyanagi-Harada syndrome in patients with Cherokee Indian ancestry.

Eight patients with Vogt-Koyanagi-Harada syndrome who have Cherokee Indian ancestry ranged from 17 to 49 years of age. Five of the patients were black, three were white. Visual acuity at the time of initial examination ranged from 20/20 to counting fingers. Clinical findings included granulomatous iridocyclitis in six patients, vitreitis in seven patients, disk edema in five patients, exudative retinal detachment in six patients, and multifocal choroidal lesions in all eight patients. All of the patients were treated with systemic corticosteroids, and they recovered visual acuity of 20/40 or better. The seven patients assayed had the HLA-DRw52 haplotype, including five who were homozygous for this allele. This finding may add to the increasing evidence that a class II HLA antigen at a D-related locus may predispose carriers to the development of Vogt-Koyanagi-Harada syndrome.

Adolescent↗

Immunohistochemical and histochemical properties of surgically excised subretinal neovascular membranes in age-related macular degeneration.

The immunohistochemical and histochemical properties of 16 surgically excised subretinal neovascular membranes from 16 patients with age-related macular degeneration were studied. Primary antisera to c-retinaldehyde-binding protein; leukocyte common antigen; factor VIII-related antigen; S-100 protein; glial fibrillary acid protein; muscle-specific actin; neuron-specific enolase; collagen types I, II, III, IV, and V; laminin; and fibronectin were used for immunohistochemical characterization of the membranes. Histochemical staining for lipid and mucopolysaccharide was performed. The results of the staining in conjunction with histologic examination showed the cellular components of the membranes to be composed of retinal pigment epithelium, inflammatory cells, vascular endothelium, glial cells, myofibroblasts, photoreceptor cells, and fibrocytes. The extracellular matrix of the membranes contained collagen types I, III, IV, and V; fibronectin; laminin; mucopolysaccharide; and lipid. These findings are consistent with the concept that subretinal neovascular membranes in age-related macular degeneration are composed of localized intra-Bruch's membrane granulation tissue proliferation associated with diffuse drusen.

Aged↗

Pathogenetic mechanisms in anterior proliferative vitreoretinopathy.

A clinicopathologic study of ten consecutive patients (ten eyes) undergoing surgery for rhegmatogenous retinal detachment with anterior proliferative vitreoretinopathy and a subsequent histopathologic, immunohistochemical, and ultrastructural study of ten enucleated eyes with anterior proliferative vitreoretinopathy were performed in order to elucidate relevant pathogenetic mechanisms. Our findings suggest that the pathogenetic evolution of anterior proliferative vitreoretinopathy occurs in three consecutive stages: (1) traction on the ciliary body and peripheral retina induced by fibrocellular contraction of the vitreous base; (2) incorporation of tractionally denuded components of the ciliary body and peripheral retina into the fibrocellular membranes overlying the vitreous base; and (3) proliferation of the incorporated components and fibrovascular ingrowth from the uvea, the retina, or both, into the fibrocellular membranes. Tractional disruption of the epithelium of the ciliary body pars plicata and breakdown of the ciliary blood-aqueous barrier are the principal pathogenetic mechanisms of chronic intractable hypotony and the post-vitrectomy fibrin syndrome in anterior proliferative vitreoretinopathy.

Adult↗

Examination of macular vitreoretinal interface disorders with monochromatic photography.

Monochromatic light accentuates details of different retinal layers because of its variable absorption and reflectance by structures both within and above these layers. Monochromatic photography was used to examine macular vitreoretinal interface abnormalities in 19 patients. Short wavelength photographs (490 nm) provided the best detail of inner retinal abnormalities, including epiretinal membranes, vitreoretinal traction, and the internal surface of confluent macular edema (pseudocyst). Although 540-nm red-free photography provided acceptable photographs, it did not provide optimal detail of inner or deep retinal abnormalities. Longer wavelengths, 585 and 610 nm, best disclosed the extent of deep retinal abnormalities, including the extent of confluent macular edema (pseudocysts) and retinal detachment that surrounded macular holes. The addition of short- and long-wave-length photography to traditional red-free photography may provide better localization, understanding, and documentation of the three-dimensional relationships in macular vitreoretinal interface disorders.

Eye Diseases↗

Surgical excision of subfoveal neovascular membranes in age-related macular degeneration.

We studied the results of surgical excision of ten consecutive subfoveal choroidal neovascular membranes in ten patients with age-related macular degeneration. The criteria for surgical eligibility included the following: (1) a clearly identifiable subfoveal membrane occupying the entire foveal avascular zone, (2) a visual acuity of 20/200 or worse, (3) minimal subretinal hemorrhage, and (4) an associated exudative macular detachment. Six of the ten patients showed visual improvement at one-month and three-month follow-up visits and seven showed visual improvement by the six-month examination. All ten maculae remained attached without recurrence of subfoveal neovascular membranes throughout the follow-up period. These results suggested that surgical excision is a viable alternative to laser photocoagulation in patients with subfoveal neovascularization in age-related macular degeneration.

Aged↗

Management of threshold retinopathy of prematurity.

The Cryotherapy for Retinopathy of Prematurity Study demonstrated the benefit of intervention for threshold disease. The authors reviewed their experience with cryotherapy, investigating the questions of treatment for bilateral disease. Between 1985 and 1990, 71 eyes from 41 infants with threshold retinopathy of prematurity were treated. Of the 65 eyes with a minimum of 3 months follow-up, only 7 eyes (11%) progressed to stage 4, although an additional 8 eyes (13%) developed a posterior retinal fold. Although the overall results are comparable to those repeated by the Cryotherapy for Retinopathy of Prematurity Study, the authors recommend treating both eyes if they reach threshold, and treating the two eyes at the same sitting.

Cryosurgery↗

Pathologic features of surgically excised subretinal neovascular membranes in age-related macular degeneration.

The histopathologic features of ten consecutive surgically excised subfoveal neovascular membranes from patients with age-related macular degeneration were examined. Ultrastructural features included the following in decreasing order of frequency: endothelium-lined vascular channels, new collagen, fibrocytes, retinal pigment epithelium, erythrocytes, and myofibroblasts. Chronic inflammatory cells were frequently evident and included macrophages, lymphocytes, and plasma cells. Basal laminar deposit or diffuse drusen were observed in six of the membranes. Photoreceptors and Bruch's membrane were each observed in three of the specimens, but were not associated with decreased postoperative visual acuity. Fibrin was observed in eight membranes, either within the stroma of the membrane or in association with subretinal hemorrhage.

Age Factors↗

The ora serrata and the spiral of Tillaux. Anatomic relationship and clinical correlation.

Conventional teaching states that the spiral of Tillaux marks the location of the ora serrata. On literature review, no source for this was found. This study explores this anatomic relationship. In 20 cadaver eyes, narrow-gauge needles were placed penetrating the center of each rectus muscle insertion, and distance to the ora was measured. Insertions ranged from 2.25 mm posterior to 2.25 mm anterior to the ora, with 90% within 1 mm of it. In ten eyes, distance from the edge of insertion also was measured. Results indicate that the centers of rectus insertions, especially the lateral rectus, approximately overlie the ora, with the edges of the insertions more posterior and variable.

Eye↗

Preservation of the anterior ciliary vessels during extraocular muscle surgery.

Conventional, full-tendon, rectus muscle surgery disrupts the anterior ciliary vessels. This may lead to anterior segment ischemia when the number of interrupted vessels is sufficient to significantly compromise anterior segment blood flow. Clinical observations and histologic studies provide new anatomic information concerning the course of the anterior ciliary vessels in the sub-Tenon's region. These studies demonstrate the feasibility of dissection and preservation of the anterior ciliary vessels during rectus muscle surgery. Dissection and preservation of 35 clinically apparent anterior ciliary vessel groups were attempted on 15 rectus muscles during strabismus surgery. The unplanned vessel destruction rate was 9.5%. Procedures included 12 recessions, 1 resection, and 2 full-tendon transpositions. The possible role of this procedure in the prevention of anterior segment ischemia is discussed.

Adolescent↗

Optic nerve enlargement and central retinal-artery occlusion secondary to retrobulbar anesthesia.

Optic nerve injury after retrobulbar injection of anesthetic agents may damage the optic nerve and vascular supply to the eye. We describe a case of documented orbital optic nerve injury with central artery occlusion after retrobulbar injection before cataract surgery. Early computed tomography documentation of optic nerve injury associated with retrobulbar injection is suggested to allow early consideration of optic nerve sheath decompression.

Aged↗

Angioid streaks associated with abetalipoproteinemia.

Angioid streaks were observed in a 31-year-old man with abetalipoproteinemia. Angioid streaks have now been described in hereditary spherocytosis, beta thalassemia, alpha thalassemia, sickle cell anemia, and acanthocytosis secondary to abetalipoproteinemia and hypobetalipoproteinemia. The nature of the association of angioid streaks and structural defects of hemoglobin and the red blood cell is not understood.

Abetalipoproteinemia↗