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Biomedical subjects

A R Irvine

Publications and source records attributed to A R Irvine.

At least 55 records · Page 3Linked to original sources
PubMed1987

Histopathology of krypton red laser panretinal photocoagulation. A clinicopathologic correlation.

The histopathologic appearance of five-day-old and 14-day-old krypton red laser-created panretinal photocoagulation lesions in the diabetic human eye is described. The five-day-old lesions were examined near the equator. The 14-day-old lesions were near the temporal arcades and optic disc. Both groups of laser lesions showed a similar degree of damage and occlusion in the lamina choriocapillaris and deeper choroidal vessels. The 14-day-old posterior laser lesions showed outer retinal damage, whereas the five-day-old peripheral lesions showed full-thickness retinal involvement, probably because the peripheral retina is approximately half the thickness of the posterior retina. The five-day-old lesions showed no evidence of repair, whereas the 14-day-old lesions showed an adhesion formed with tight junctions binding Müller's fibers to retinal pigment epithelium.

Diabetic Retinopathy↗
PubMed1987

The management of subretinal gas following attempted pneumatic retinal reattachment.

Pneumatic retinopexy is a recently described procedure for treating retinal detachments with cryotherapy and intraocular gas injection, rather than scleral buckling. Prospective studies are underway to assess its safety and efficacy. One potential complication of this technique is persistent detachment due to subretinal gas. We report seven cases of subretinal gas following attempted pneumatic retinal reattachment. In all cases, multiple fish-egg gas bubbles were present following injection; some of these bubbles gained access to the subretinal space during the early postoperative period. The subretinal gas gave the detached retina a pearly, dome-shaped, refractive sheen. Three cases were managed by positioning the patients' heads to allow the subretinal gas to pass through the retinal break back into the vitreous cavity. One case underwent successful scleral buckling that closed the retinal break despite the presence of a small subretinal gas bubble. Three cases required vitrectomy, air-fluid exchange, and cryotherapy or endolaser treatment. In five of the seven eyes the retina was eventually reattached successfully.

Adult↗
PubMed1986

The diagnoses most commonly missed by ophthalmologists referring patients for fluorescein angiography.

A tally of misdiagnoses in patients referred to a fluorescein angiography service disclosed that three conditions made up the majority of all misdiagnoses. These conditions were chronic branch retinal vein obstruction, old or chronic central serous choroidopathy, and retinal arterial macroaneurysms with subretinal or subhyaloid hemorrhage. These three conditions proved to be talented mimics with a wide variety of presentations.

Aneurysm↗
PubMed1986

Inferences from beading of a retinal vein draining a choroidal melanoma.

Beading of a retinal vein draining a choroidal melanoma is reported, showing that the endothelial proliferation producing the beading is a response to some blood borne factor(s) traversing the vein and that retinal capillary non-perfusion adjacent to the beaded vein is not a necessary part of the process.

Capillaries↗
PubMed1986

Extended retinal tamponade in the treatment of retinal detachment with proliferative vitreoretinopathy.

We have used intraocular sulphur hexafluoride or liquid silicone as an adjunct to vitreous surgery in the treatment of a non-randomised sequential series of 19 eyes with retinal detachment complicated by proliferative vitreoretinopathy. We have studied the surgical results and complications of these two tamponades and drawn preliminary conclusions on their use in retinal reattachment surgery. After a seven-month minimum follow-up 13 (68%) of the eyes have reattached retinas. Six (60%) of 10 eyes treated only with silicone have reattached retinas, and four (67%) of six eyes treated only with sulphur hexafluoride gas tamponade have reattached retinas. An additional three eyes treated initially with silicone oil subsequently developed retinal detachments; all were successfully reattached with sulphur hexafluoride tamponade after silicone oil removal. Intraoperative pneumatic retinal reattachment to assess relief of retinal traction combined with the production of widespread chorioretinal adhesions to wall off persistent anterior traction and detachment, as well as extended postoperative gas tamponade of the retina, appears to enhance the surgical results in retinal detachment complicated by proliferative vitreoretinopathy. Silicone oil tamponade of the retina appears to be useful in cases where retinal traction cannot be entirely relieved and in patients who are unable to tolerate the head positioning required for effective gas tamponade of the retina. A controlled clinical study recently begun will be required to define further the precise role of these methods of retinal tamponade.

Adult↗
PubMed1986

Propionibacterium acnes endophthalmitis seven months after extracapsular cataract extraction and intraocular lens implantation.

We present a case of endophthalmitis caused by Propionibacterium acnes seven months following extracapsular cataract extraction and intraocular lens implantation. The markedly delayed clinical course of endophthalmitis associated with this organism appears to be highly stereotypical. Recognition and treatment of this complication of cataract surgery allows an excellent chance at cure.

Ampicillin↗
PubMed1985

The focal nature of retinal illumination from the operating microscope.

A photographic demonstration of the focal nature of the retinal illumination from the operating microscope is presented. It illustrates that under normal anterior segment operating procedures, the side-mounted and coaxial illuminators are imaged as small, intense spots on the retina. The irradiance (in watts per square centimeter) of these spots is reduced by their defocusing in aphakia. Cautionary attention is drawn to the danger of allowing these retinal hot spots to be imaged on or near the macula during surgery.

Animals↗
PubMed1985

Epidemic postsurgical Candida parapsilosis endophthalmitis. Clinical findings and management of 15 consecutive cases.

Fifteen cases of postoperative Candida parapsilosis endophthalmitis occurring secondary to a contaminated lot of an irrigating solution were studied. All patients underwent a vitreous tap or diagnostic and therapeutic vitrectomy. Eleven of the 15 specimens were positive for the organism. Fourteen patients were treated with pars plana vitrectomy surgery. All patients were treated with intravitreal amphotericin B and systemic amphotericin B and 5-fluorocytosine. Two clinical recurrences were successfully treated with intravitreal amphotericin B, removal of the pseudophakos, and oral ketoconazole. The intraocular lens was retained in 11 of the 14 pseudophakic patients. Final visual acuities ranged from 20/25 to no light perception with eight of 15 patients having 20/60 or better visual acuities. Measurable levels of intraocular amphotericin B were found after systemic amphotericin B administration. Two patients with totals of 20 and 30 micrograms of intravitreal amphotericin B over 48 and 96 hours, respectively, had near normal ERGs one year later. Posterior capsulotomy and vitrectomy appear to decrease amphotericin B toxicity and allow sequential intraocular injection of this drug within a short time period.

Aged↗
PubMed1984

Retinal damage from the illumination of the operating microscope. An experimental study in pseudophakic monkeys.

An experimental study of retinal damage from the coaxial illumination of the operating microscope was performed in pseudophakic rhesus monkeys. The threshold exposure time for production of an ophthalmoscopically visible lesion was determined, and the lesions were studied with light and electron microscopy. At the "high" illumination setting, the threshold exposure was less than 7 1/2 minutes and consecutive exposures of lesser duration had an additive effect. Histologically, the lesions were identical to those which other authors have described as primarily due to the shorter wavelengths or "blue light mechanism" of damage.

Animals↗
PubMed1983

Helium ion therapy for choroidal melanoma.

Eighty-two patients with choroidal melanomas were treated with helium ion charged particle irradiation. Seventy-eight of 82 patients have either remained stable or demonstrated tumor shrinkage. Forty-five of 46 patients followed for at least 1 year after therapy have demonstrated tumor regression with a mean tumor shrinkage of approximately 31%. No tumor-related mortality has been observed. The most effective method of choroidal melanoma management is unclear. Charged particle external beam irradiation may be more applicable and have less ocular morbidity than either radioactive plaques or photocoagulation.

Adult↗
PubMed1983

Light-induced maculopathy from the operating microscope in extracapsular cataract extraction and intraocular lens implantation.

A characteristic macular lesion has been noted in six patients who underwent extracapsular cataract extraction with posterior chamber lens implantation. The lesion appeared similar to that which other investigators have produced in monkeys as a response to the coaxial illumination of the operating microscope. On the first or second postoperative day, the lesion appeared as an oval area of mild yellow-white discoloration of the retina; gradually it developed mottled pigmentation over the next few weeks. The pigmentary changes were often subtle, but fluorescein angiography revealed a characteristic sharply circumscribed lesion. In most of our patients the lesion was just above or below the foveola, so that central vision returned to normal, but a paracentral scotoma was present. These findings should encourage the clinician to heed the warnings of those laboratory studies which have shown the phototoxic potential of the operation microscope's unfiltered coaxial illumination and force us to re-examine our filters and operating techniques.

Aged↗
PubMed1982

Vitrectomy in infants and children with retinal detachments caused by cicatricial retrolental fibroplasia.

Four infants and one child with retinal detachments from cicatricial retrolental fibroplasia involving traction judged too severe to be relieved by scleral buckling alone underwent lensectomy and vitrectomy. Three retinas were successfully reattached. Because of the incomplete development of the pars plana in infants and the manner in which peripheral retina is pulled anteriorly to a position near or in contact with the posterior lens capsule, entry through the pars plana can create iatrogenic tears in the peripheral retina or introduction of irrigation fluid under the retina. Our experience has shown that a small contact lens makes it possible to work in the posterior vitreous cavity through the limbal approach in these infants. The circumferential traction produced by the ring of fibrovascular proliferation behind the lens can be relieved and tractional bands running forward from the posterior pole can be cut. Fibrovascular proliferative tissue lying on the posterior pole, however, proved resistant to membrane peeling or dissection, and its severity seemed to determine the success or failure of the surgery.

Child, Preschool↗