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Biomedical subjects

A R McPherson

Publications and source records attributed to A R McPherson.

8 recordsLinked to original sources
PubMed1989

Combined hamartoma of sensory retina and retinal pigment epithelium.

We report two cases of combined hamartoma of the sensory retina and retinal pigment epithelium (CHR-RPE) in which apparent growth of the lesion was observed. In case 1, the eye was enucleated with a presumed diagnosis of juxtapapillary malignant melanoma. Histopathologically, the enucleated globe showed an elevated peripapillary mass containing disorganized retinal tissue intermixed with vascular and glial elements as well as tubules of proliferating retinal pigment epithelium. We have summarized the clinical features of 53 patients with CHR-RPE reported between 1952 and 1988 excluding the cases compiled by the Macular Society Collaborative Study. While the latter study found an equal sex predilection among their cases, we found a 70% male preponderance among the 53 patients. Of the 54 lesions observed in 53 patients, 76% were juxtapapillary, 17% were macular, and 7% were peripheral. Furthermore, periodic follow-up examination disclosed apparent enlargement of the mass in six patients, five of whom underwent enucleation of the globe for suspected melanoma.

Child↗
PubMed1987

Treatment of juxtafoveal and parafoveal neovascular membranes with monochromatic green argon photocoagulation: green laser.

Sixty eyes in 58 patients with either juxtafoveal or parafoveal neovascular membranes were treated with monochromatic green argon photocoagulation. The visual acuity was stabilized or improved in 73.2% (22 eyes) in both the juxtafoveal and parafoveal groups. Total eradication of the neovascular membranes was possible in 86.6% (26 eyes) in the juxtafoveal group and 93.4% (28 eyes) of the parafoveal group. This study suggests that successful treatment of both juxtafoveal and parafoveal neovascular membranes can be accomplished with monochromatic green argon photocoagulation.

Choroid↗
PubMed1986

An interpretation of retinopathy of prematurity in terms of spindle cells: relationship to vitamin E prophylaxis and cryotherapy.

Spindle cells in the hyperoxygenated, avascular, vanguard retina are proposed to be the peripheral inducers of the neovascularization associated with retinopathy of prematurity (ROP). The induction of ROP is conceptualized in terms of three basic events. First, activation of spindle cells results initially in the increase in gap junctions between adjacent spindle cells, secondarily in the increase in cytoplasmic volume of rough endoplasmic reticulum, and ultimately in the synthesis and secretion of angiogenic factors Second, maturation of spindle cells is associated with a decrease in gap junctions, a diminished cytoplasmic volume of rough endoplasmic reticulum, and a cessation of synthesis and secretion of angiogenic factors. Third, myofibroblasts invade the vitreous concomitantly with spindle cell maturation and provide the tractional force that can produce retinal separation. The extent of interstitial retinol binding protein within the subretinal space explains the gestational-age-dependent efficacy of vitamin E in suppressing the development of severe ROP. The kinetics of both spindle cell activation/maturation and myofibroblast invasion predict the efficacy of appropriately timed and placed transretinal cryotherapy.

Cell Movement↗
PubMed1985

Pigmented free-floating vitreous cysts in two young adults. Electron microscopic observations.

Pigmented free-floating vitreous cysts were observed in two young adults. In both patients, the cyst was in the visual axis; however, the size and extent of pigmentation of the cyst wall compromised the visual acuity only in case 1. In this case, the vitreous cyst was aspirated through the pars plana and studied by light and electron microscopy. Histopathologically, the cyst was lined by a heavily pigmented layer of cuboidal cells intermixed with sheets of nonpigmented cells forming papillae. Ultrastructurally, the pigmented cells contained predominantly large, mature melanosomes (0.9-2.2 micron). Scattered immature melanosomes with a scarcity of mitochondria and other cytoplasmic organelles were present. Additionally, the cells were invested by a thin polarized basement membrane and displayed apical microvilli. Numerous microvillous processes were noted under the plasmalemmae and between adjacent cells. The results of the light and ultrastructural studies provide support for the hypothesis that the cyst in case 1 originated from the pigment epithelium. The possibility of a traumatic etiology is proposed for these pigmented vitreous cysts. If significant visual impairment is present, surgical removal of the cyst through a pars plana approach can be safely performed as in our case 1.

Adult↗
PubMed1985

Malignant melanoma of the choroid: treatment with episcleral 198Au plaque and xenon-arc photocoagulation.

A method of treatment for posteriorly located malignant melanomas of the choroid is reviewed. Twenty-six patients have been treated either by radioactive gold (198Au) seed radiation plaque, alone or in combination with postradiation xenon-arc photocoagulation. Success, defined as the preservation of the globe with tumor ablated or regressed, was achieved in 92.3% of the treated eyes. These patients have been followed from 1 to 8.5 years, with an average follow-up of 44.84 months. Fifteen out of 26 patients (57.69%) had a final visual acuity of 20/50 or better. The main complications were radiation retinopathy (19.2%) and cystoid macular edema (19.2%). There were two enucleations, one after 29 months and one after 24 months following treatment.

Adult↗
PubMed1979

Anterior segment abnormalities in cicatricial retinopathy of prematurity.

Abnormalities that occur in the anterior segments of patients with retinopathy of prematurity have been studied in 72 eyes of 36 patients. The anterior chamber depth, the placido disc image on the cornea, the distortion of polarized light by corneal stress, and keratometry readings were recorded. There was a highly significant correlation between anterior chamber depth, retinopathy of prematurity, and keratometry readings (p less than .001). These findings emphasize the importance of careful follow-up examinations of the anterior segment in retinopathy of prematurity because cataracts, band keratopathy, acute hydrops, and angle-closure glaucoma can progressively occur as complications.

Adolescent↗