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Biomedical subjects

A Patz

Publications and source records attributed to A Patz.

At least 109 records · Page 6Linked to original sources
PubMed1976

Cystoid maculopathy in diabetics.

Three patients with long-standing diabetes manifested reduced visual acuity and notable bilateral symmetrical cystoid maculopathy, with no other sign of meaningful background diabetic retinopathy, eg, minimal to no microaneurysms, hemorrhages, or exudates. Results of fluorescein angiography showed that the entire retinal capillary bed in the macula was dilated and leaked fluorescein diffusely and profusely, but also showed that there was excellent capillary perfusion. Argonlaser photocoagulation was applied to one eye of each patient in an attempt to resolve the cystoid maculopathy. The laser treatment effectively resolved the edema in the specific areas of treatment, but the foveal and perifoveal areas, which were not treated, showed no areas of resolution of the cystoid edema in two cases and no improvement (and no decrease) in visual acuity in all three cases.

Adult↗
PubMed1976

Subretinal neovascularization developing after prophylactic argon laser photocoagulation of atrophic macular scars.

Two patients who had lost central vision in one eye due to a histoplasmic disciform macular scar received prophylactic argon laser photocoagulation to one or more atrophic lesions (histo spots) in the second macula in an effort to reduce the risk of developing active neovascularization in the second eye. Despite this prophylactic treatment, both patients developed a choroidal neovascular membrane from the photocoagulation scar.

Adult↗
PubMed1976

Diabetic macular edema.

Photocoagulation by either the argon laser or xenon arc instruments has been reported to have a beneficial effect in selected patients with macular edema. Treatment is not effective in all cases; indeed, in some patients with perifoveal capillary closure, severe macular edema, long-standing organized hard exudates, or significant cystoid maculopathy, treatment has proved to be ineffective. Findings associated with a generally favorable or an unfavorable prognosis following photocoagulation are discussed in this chapter, along with proper management of the patient's systemic status, with particular emphasis on the problem of hypertension, important in patients with diabetic macular edema. Because the results of photocoagulation are limited in a significant number of patients, further research into the basic pathogenetic mechanisms involved in increased retinal capillary permeability to recommended, with the hope of providing more effective therapy.

Adult↗
PubMed1976

Argon laser photocoagulation in ocular histoplasmosis syndrome.

Argon laser photocoagulation was performed on 30 patients with ocular histoplasmosis syndrome involving the macula. Selection of patients for photocoagulation was dependent upon locating the sub-retinal neovascularization (SRNV) at least one vein-width removed from the capillary-free zone of the fovea on fluorescein angiography. Of the 30 treated patients, 27 maintained or improved visual acuity an average of 1 1/2 years following photocoagulation.

Adult↗
PubMed1976

Components of vitreous-soluble proteins: effect of hyperoxia and age.

In young puppies, the retina, which is incompletely vascularized at birth becomes fully vascularized at approximately four weeks of age. During this period of vessel growth the total content of vitreous-soluble protein was found closely associated with the rate of retinal vessel growth. As vascularization progressed toward completion, the protein originally present at birth decreased to a negligible or undetected amount. Intravitreal neovascularization was produced in young puppies by exposure to 85 per cent oxygen for four days, then removal to room air. This form of neovascularization resembles closely that observed in human proliferative diabetic retinopathy. The oxygen treatment, which initially produced retinal capillary closure, then neovascularization, was associated with a retention of vitreous-soluble protein at a high level for several days. The results raise the possibility that the vitreous protein(s) may be fundamentally involved in the process of normal vascularization of the retina and in retinal neovascularization.

Age Factors↗
PubMed1976

Prolonged tumor dormancy by prevention of neovascularization in the vitreous.

Tumors release a diffusible substance that stimulates neovascularization. To study the neovascularization that occurs in diabetic retinopathy, we implanted V2 carcinomas and mouse ependymoblastomas into the vitreous of experimental animals. In the vitreous, unlike previous sites, the tumors failed to stimulate neovascularization. They grew for weeks as small, unvascularized, three-dimensional aggregates of cells. Explosive growth into a large, vascularized mass occurred when the avascular tumors reached the retinal surface. The vitreous proved to be a valuable model for observing the in vivo growth of small, solid tumors. Xenografts survived for months without evidence of immune rejection. The consequence of the prolonged avascular state is the restriction of tumor size. The normal vitreous may act to inhibit capillary proliferation. An understanding of the mechanism for maintaining the avascular state may lead to therapeutic blockade of neovascularization. This would be important in the management of diabetic retinopathy and neoplasia.

Animals↗
PubMed1976

Argon laser iridotomy: an experimental and clinical study.

Iridotomies were made in rabbit and human eyes using a continuous wave argon laser. Several of these have been studied histologically to determine the short- and long-term effects on the iris, cornea, lens and retina. Thirty-three eyes of patients with angle-closure glaucoma were treated by argon laser iridotomy and followed for periods of up to twelve months. In two eyes, planned cataract surgery was performed shortly after the laser iridotomy and histologic specimens of the iris were examined. From the experimental and clinical studies, an evaluation was made of the complications and clinical usefulness of the continuous wave argon laser as a means to produce iridotomies for the treatment of angle-closure glaucoma. Further long-term controlled studies are recommended to document the role of laser iridotomy.

Animals↗
PubMed1975

The role of oxygen in retrolental fibroplasia.

The effects of oxygen in the immature or incompletely vascularized retina are conveniently divided into an initial vasoconstrictive and obliterative stage and a secondary vasoproliferative response that occurs after removal of the subject from an enriched oxygen environment. Vasoproliferation starts at the zone of perfused and nonperfused retina. The incompletely vascularized retina is uniquely responsive to these oxygen-induced changes. After vascularization is complete and the retinal vessels reach the ora, the susceptibility to hyperoxia disappears. The vessels in the temporal periphery of the retina have a peculiar susceptibility to the primary and secondary effects of hyperoxia on the immature retina. Ophthalmoscopic examination of the temporal periphery therefore should always be done carefully in the premature infant or in older individuals giving a history of prematurity. The indirect ophthalmoscope provides the most satisfactory instrument for examination. The incidence of retrolental fibroplasia has been greatly reduced following the incrimination of oxygen as its principal cause. Further studies are still required to determine precise blood oxygen levels that are safe for the premature retina and to discover other factors that may play a role in the pathogenesis or RLF.

Animals↗
PubMed1975

Comparison of xenon arc and argon laser photocoagulation in ocular histoplasmosis.

Argon laser and xenon arc photocoagulation can be utilized to obliterate choroidal neovascularization in selected cases of macular histoplasmosis. Central vision can be preserved in many instances if criteria for patient selection, treatment techniques, and method of follow-up, as described in this chapter, are adhered to rigidly. Of 40 patients treated with argon laser photocoagulation, 75 percent maintained or improved central vision an average of one year following treatment. Nonetheless, there is a definite need for a prospective controlled study to document the efficacy of this mode of treatment on a long-term basis.

Adult↗
PubMed1975

A follow-up of blind diabetic patients.

This report concerns the subsequent fate of 95 blind diabetics who were using a Seeing Eye guide dog in 1964. In 1973, 9 years later, 40 were known to be dead, 31 were known to be alive, and no data were available on 24. The average interval from onset of severe blindness to death in 37 of the 40 who had died is 9.4 years. The mean age at death was 43.2 years for the group. This compares favorably to our original study which showed an average survival from onset to blindness to death of 5.8 years, and an average age at death of 35.9 years. Because follow-up data are incomplete for the 1964-1973 interval, the true figures may be poorer than the ones reported now. In any case, it is apparent that the life expectancy of the blind diabetic is still poor after the onset of blindness from severe retinopathy.

Adult↗