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Biomedical subjects

A J Packer

Publications and source records attributed to A J Packer.

31 records · Page 2Linked to original sources
PubMed1985

Systemic absorption and cardiovascular effects of phenylephrine eyedrops.

We studied 24 patients undergoing vitreoretinal surgery to compare the systemic absorption and cardiovascular effects of 2.5% aqueous and 10% viscous ophthalmic solutions of phenylephrine hydrochloride. Plasma levels measured in patients receiving two drops of 10% viscous solution were consistently higher ten, 20, and 60 minutes after instillation (P less than .02). Although the mean systolic and diastolic blood pressure was generally higher with the 10% viscous solution, the difference was not statistically significant. Blood pressure was high in several isolated cases. Because maximum plasma levels are achieved within ten to 20 minutes after topical instillation, phenylephrine eyedrops should be administered under close observation so that if an adverse reaction occurs it can be readily treated.

Absorption↗
PubMed1985

Ocular neovascularization. Tissue culture studies.

The proliferative activity of a number of intraocular fluids, bovine retinal extract, and normal serum (from humans and cynomolgus monkeys) was investigated by in vitro tissue culture studies, with the use of tritiated thymidine incorporation by the cultured endothelial cells of human umbilical veins. There was increased tritiated thymidine incorporation by (1) the aqueous, vitreous, and intraocular fluid (IOF) (which filled the eye after lensectomy and vitrectomy) removed from cynomolgus monkey eyes with iris neovascularization or with neovascular glaucoma (NVG) that developed after experimental retinal vein occlusion, (2) by aqueous and vitreous removed from human eyes with NVG or proliferative diabetic retinopathy; (3) by the serum, and (4) by the bovine retinal extract. However, tritiated thymidine incorporation was not increased by the normal aqueous, vitreous, or IOF.

Animals↗
PubMed1984

Hematoporphyrin photoradiation therapy for iris neovascularization. A preliminary report.

Photoradiation therapy is a new technique currently under clinical investigation for the treatment of a variety of solid malignant tumors. The technique involves intravenous (IV) administration of hematoporphyrin derivative, a photosensitizing compound that is preferentially retained by malignant cells, and photoactivation of a neoplasm with red light (630 nm) to obtain selective destruction of cancer cells. A modification of this technique was used to treat iris neovascularization produced in a primate model of retinal vein occlusion. Following IV injection of hematoporphyrin derivative, the anterior surface of the iris was exposed to red light for 30 to 45 minutes. In the four eyes treated, there was a marked reduction of fluorescein leakage from the neovascular tissue within 24 hours following treatment. Histologic examination of two eyes demonstrated a selective response of the iris neovascularization to this therapy, with apparent preservation of surrounding tissue.

Animals↗
PubMed1984

Punctate inner choroidopathy.

Ten moderately myopic women had blurred vision, light flashes, or paracentral scotomas associated with small yellow-white lesions of the inner choroid and pigment epithelium. Most lesions had an overlying serous detachment, were hyperfluorescent, and leaked fluorescein during the acute phase. The lesions healed into atrophic scars and became progressively more pigmented with time. Subretinal neovascular membranes later developed from scars in six patients. Vision was usually only minimally affected unless the lesions were subfoveal or unless choroidal neovascular membranes subsequently occurred. Extensive laboratory studies were noncontributory.

Adult↗
PubMed1984

Aberrant regeneration involving the oculomotor and abducens nerves.

An unusual case of severe head trauma is reported with postoperative 'total' ophthalmoplegia of the right eye. Subsequent recovery led to an apparent transposition of right medial and right lateral rectus function. Optokinetic stimulation induced convergence nystagmus when the target was moved to the patient's left, and a divergence nystagmus when the target was moved to the patient's right. In addition, attempted lateral gaze induced ipsilateral pupillary constriction. Aberrant regeneration involving the right abducens and right oculomotor nerves is proposed as the underlying mechanism.

Abducens Nerve↗
PubMed1984

The tunnel sponge--an explant for retinal detachment surgery.

The tunnel sponge explant for retinal detachment surgery is a modification of the cylindrical, silastic sponge. A central tunnel exists along the length of the sponge allowing a silicone band to be threaded internally. A high, localized indentation can be achieved as well as encirclement with minimal volume displacement of the globe.

Equipment and Supplies↗
PubMed1983

Serous choroidal detachment after retinal detachment surgery.

In a prospective evaluation of 154 consecutive retinal detachment procedures, the incidence of choroidal detachment was 39.6%. The age of the patient, drainage of subretinal fluid, and vortex compression by the explant seem to be the most important correlative factors. Scleral explants up to one quadrant in circumferential length produced a minimal incidence (7.7%) of choroidal detachment. Posterior positioning of the explant also affected the incidence of choroidal detachment. After follow-up, ranging from six to 48 months, postoperative visual acuity was recorded for "macula-on" as well as "macula-off" retinal detachments. In the macula-on group, 78.6% of the patients with choroidal detachment retained a visual acuity of 20/50 or better compared with 82.8% of the patients without choroidal detachment. In the macula-off group, 43.2% of the patients with choroidal detachment achieved a visual acuity of 20/50 or better compared with 55.1% of the patients without choroidal detachment. The final anatomic success rate was 86.5% for eyes with choroidal detachment and 92.3% for eyes without choroidal detachment.

Age Factors↗
PubMed1983

Retinal periphlebitis as an early sign of bacterial endophthalmitis.

Retinal periphlebitis appeared as an early sign of bacterial endophthalmitis in three patients, a 36-year-old man with bilateral Terson's syndrome who underwent vitrectomy for dense vitreous hemorrhage, a 78-year-old woman who had had intracapsular cataract extraction and penetrating keratoplasty after repair of a wound leak and pars plana anterior membranectomy, and an 18-year-old man who suffered an accidental penetrating ocular injury. Staphylococcus organisms were recovered from vitreous samples in all three cases. Although recovery of useful vision is rare after postvitrectomy endophthalmitis, the first patient attained a final visual acuity of 20/50. The visual acuities of the second and third patients returned to 20/25 and 20/20 respectively. In an experimental primate (cynomolgus monkey) model of bacterial endophthalmitis, retinal periphlebitis developed early and closely resembled the clinical findings in humans. Histopathologic studies confirmed the presence of inflammatory cells that infiltrated the retinal venules.

Adolescent↗
PubMed1982

Ocular trauma.

This article guides the primary care physician in determining whether an injury to the eye requires immediate care, immediate referral, or routine treatment. Prevention of ocular trauma through government regulation and the wearing of protective eye gear is emphasized.

Burns, Chemical↗
PubMed1981

The effect of timolol and acetazolamide on transient intraocular pressure elevation following cataract extraction with alpha-chymotrypsin.

Elevated intraocular pressure (IOP) early after cataract extraction with alpha-chymotrypsin is a well-described, common occurrence. To study the incidence of pressure increase and the efficacy of medical therapy, IOP was monitored every 12 hours beginning on the first postoperative day in 68 patients after otherwise uncomplicated intracapsular cataract extraction performed with one milliliter of alpha-chymotrypsin and wound closure with multiple sutures. Patients were randomly assigned to one of three groups: treatment with oral acetazolamide, treatment with topical timolol, or no treatment. Without prophylactic treatment, the prevalence of pressure elevation at 24 hours postoperatively was 69% with IOP greater than or equal to 25 mm Hg; 29% with IOP greater than or equal to 40 mm Hg. This was independent of the type of sutures used (10--0 nylon or 9--0 silk). The patients of four different surgeons had similar rates of occurrence of postoperative glaucoma. Both timolol and acetazolamide were essentially equally effective in lowering IOP in these patients. No adverse side effects were observed. With these effective treatments available if needed, we believe that routine monitoring of the IOP by applanation tonometry during the early postoperative course provides a good opportunity for reducing the risk of complications from excessive intraocular pressure.

Acetazolamide↗
PubMed1978

Experimental cataract production by high frequency ultrasound.

In vivo animal experiments were performed to study the cataractogenic effects of high-frequency, high-intensity ultrasound. A series of anesthetized rabbits was insonified with quantified exposures of ultrasound using a 9.8 MHz focused ultrasonic beam. Ophthalmoscopic and slit lamp examinations revealed small haze cataracts as the first stage of lenticular damage. Larger exposures produced totally opaque cataracts. These first appeared as fine white threads surrounded by haze cataracts. The intensity-exposure time conjugates required to produce haze cataracts were determined over times ranging from 35 msec to 5 sec. At short times (under 100 msec) a relatively constant amount of energy was needed for cataract production. At longer times, the requried energy progressively increased. This observation, together with the physical appearance of these cataracts, suggests that those lesions are the result of thermal phenomena.

Animals↗