PubMed Health⌕ Search

Biomedical subjects

A J Packer

Publications and source records attributed to A J Packer.

At least 19 recordsLinked to original sources
PubMed1998

Outcomes of vitreoretinal surgery in patients with X-linked retinoschisis.

BACKGROUND AND OBJECTIVE: To assess the outcomes of vitreoretinal surgery in the treatment of vision-threatening posterior segment complications of X-linked retinoschisis. PATIENTS AND METHODS: The authors performed a retrospective analysis of 16 eyes from 11 patients who underwent vitreoretinal surgery. All the patients had a documented positive family history of X-linked retinoschisis, and all patients had bilateral macular disease. RESULTS: The ages of the patients ranged from 14 months to 37 years (mean age 15.1 years; median age 11.5 years), and postoperative follow-up ranged from 3 months to 10 years (mean 2.8 years; median 1 year). The indications for surgical intervention included rhegmatogenous retinal detachment (12 eyes), vitreous hemorrhage (2 eyes), progression of the schisis cavity through the fovea (2 eyes), cataract associated with a persistent hyperplastic primary vitreous-like condition (2 eyes), and exudative maculopathy (1 eye). The primary surgical intervention included pars plana vitrectomy alone (7 eyes), pars plana vitrectomy and pars plana lensectomy (4 eyes), and a scleral buckle procedure alone (5 eyes). Surgical success (defined as reattachment of the retina, removal of media opacities, or arrest of schisis progression) was achieved in 14 of 16 eyes, after an average of 1.2 procedures per eye. The major reason for reoperations was recurrent retinal detachment due to proliferative vitreoretinopathy. Two eyes were eventually enucleated due to pain associated with neovascular glaucoma resulting from recurrent retinal detachment. Of the remaining 14 eyes, visual acuity improved in 8 eyes and remained unchanged in 6 eyes. CONCLUSION: Vitreoretinal surgery is often helpful in stabilizing or improving visual function in patients with posterior segment complications from X-linked retinoschisis.

Adolescent↗
PubMed1991

Correlation between vitreous pigment granules and retinal breaks in eyes with acute posterior vitreous detachment.

The authors prospectively studied 106 consecutive phakic eyes with acute posterior vitreous detachment to determine the correlation between anterior vitreous pigment granules and retinal breaks. Pigment granules were identified in 15 eyes (14.1%), all of which had either a flap or an operculated retinal break. A retinal tear was found in only one eye without pigment granules (P = 0.000). Other factors demonstrating a statistically significant association with retinal breaks included grossly visible preretinal or vitreous blood (P = 0.039) and male gender (P = 0.000). In the absence of other ocular pathology, the presence of vitreous pigment granules identifies a very high-risk group of acute posterior vitreous detachment patients.

Acute Disease↗
PubMed1989

The site of operating microscope light-induced injury on the human retina.

We determined the site of the focal illumination from the Zeiss OPMI-6 operating microscope on the retina of the phakic and aphakic human cadaver eye by directly observing the illuminating element image on the posterior scleral surface of the globe. With the eye straight ahead and the operating microscope level, the focal oval area of retinal illumination was located superior to the foveola in both the phakic and aphakic eye. Tilting the operating microscope 10 degrees toward the surgeon displaced the entire illuminating element image 0.50 mm below the foveola in the phakic eye and 0.25 mm below the foveola in the aphakic eye. Rotating the eye inferiorly 10 degrees displaced the entire illuminating element image 1.0 mm below the foveola in the phakic eye and 1.25 mm below the foveola in the aphakic eye. Centering the field of view superiorly (viewing the superior limbus) paradoxically displaced the illuminating element image inferiorly, resulting in central foveal illumination. Foveal light exposure was avoided in most eye positions by tilting the microscope at least 10 degrees toward the surgeon.

Aphakia↗
PubMed1989

Procoagulant effects of intraocular sodium hyaluronate (Healon) after phakic diabetic vitrectomy. A prospective, randomized study.

A procoagulant effect was reported previously after injection of 0.50 to 0.75 ml of sodium hyaluronate (Healon) into the vitreous cavity at the end of phakic diabetic vitrectomies. A multicenter, randomized, prospective trial was done to study this effect. In the treatment group the media was clear in 50% of eyes in the immediate postoperative period compared with only 8% in the control group. At 2 to 6 weeks, there was no statistically significant difference between the two groups. The authors conclude that such sodium hyaluronate injection provides clear media in a significant number of eyes in the immediate postoperative period, potentially allowing thorough postoperative evaluation and early retinal photocoagulation if needed.

Adult↗
PubMed1989

Embolic anterior ischemic optic neuropathy.

The presumed cause of anterior ischemic optic neuropathy is atherosclerotic vascular changes. Small-vessel occlusive vascular disease most likely causes occlusion of one or more posterior ciliary arteries, compromising blood flow to the optic nerve head and choroid. We present the case of a 59-year-old black man with cholesterol emboli within the retinal vasculature combined with a clinical picture of anterior ischemic optic neuropathy and choroidal nonperfusion demonstrated by i.v. fluorescein angiography. We believe this is evidence that, in a rare case, embolic phenomena may be the cause of anterior ischemic optic neuropathy.

Arteriosclerosis↗
PubMed1987

A model for predicting the site of paraxial retinal lesions secondary to "coaxial" operating microscope illumination systems.

We measured a 15 +/- 2-mm displacement of the illuminating element of the coaxial operating microscope from the true optical center of the microscope. We further calculated the displacement of the image of the illuminating element of the operating microscope on the retina of the simplified schematic eye and found that the "coaxial" operating microscope would focus the light between 1.3 and 1.8 mm superior to the fovea of the eye, depending on the theoretical refractive status of the simplified eye. Actual measurements on a simulated retina (35-mm camera) confirmed the calculated displacements. The deviation varied with eye tilt and microscope position. We also found that the maneuvers commonly used by anterior segment surgeons of tilting the microscope and rotating the eye downward tended to displace the image of the illuminating element closer to the fovea, increasing the chance for symptomatic retinal damage. A combination of such maneuvers may reduce the potential for clinically significant retinal phototoxicity by displacing the light further inferior to the fovea.

Humans↗
PubMed1987

Diabetic retinopathy. Still an important complication.

Diabetic retinopathy is a leading cause of blindness. The two forms of retinopathy are background (nonproliferative) and proliferative. Risk for retinopathy increases with the duration of diabetes. Therefore, diabetics need to have regular eye examinations, including specific techniques, to detect subtle retinal changes. Timely ophthalmologic referral is crucial to maximize potential visual results. Patients with macular edema may be candidates for focal laser therapy. Those with proliferative retinopathy may be treated with panretinal laser photocoagulation, which causes regression of neovascularization, or vitrectomy to remove vitreous hemorrhage and repair complicated retinal detachments.

Diabetic Retinopathy↗
PubMed1987

Diagnosis of neuronal ceroid lipofuscinosis by ultrastructural examination of peripheral blood lymphocytes.

A 7-year-old child with a history of seizures, psychomotor regression, and progressive visual loss was found to have juvenile type neuronal ceroid lipofuscinosis on the basis of characteristic ophthalmoscopic and electroretinographic findings. Although transmission electron micrographs of two separate skin biopsy specimens were normal, peripheral blood lymphocytes were vacuolated and demonstrated, by ultrastructural examination, characteristic "fingerprint profiles" confirming the diagnosis. Peripheral blood lymphocytes from the patient's mother, who had an acquired seizure disorder, demonstrated vacuolated lymphocytes with membranous formations and osmophilic granular bodies, as revealed by electron microscopy. Examination of peripheral blood lymphocytes can be a sensitive diagnostic test in suspected neuronal ceroid lipofuscinosis and may be useful in identifying carriers or family members in the early clinical stages of the disease.

Child↗
PubMed1986

Primate model of neovascular glaucoma.

Iris neovascularization has been reproducibly created in cynomolgus monkey eyes by argon laser occlusion of retinal veins. Pre-treatment of the eyes with lensectomy and vitrectomy (before the retinal vein occlusion) led to a more rampant development of the iris neovascularization in all eyes, as well as development of neovascular angle closure glaucoma in two of the 12 eyes. Histopathologic examination confirmed the finding of neovascular angle closure. This primate model may allow further investigation into the causes and therapy of neovascular glaucoma.

Animals↗
PubMed1986

Terson's syndrome. Clinicopathologic correlations.

In seven cases of Terson's syndrome, an elevated, dome-shaped, membrane was detected in the posterior pole by ophthalmoscopy, echography, or during pars plana vitrectomy. Light and electron microscopic examination of two additional eyes obtained postmortem from an acute case of Terson's syndrome revealed that the posterior vitreous face was elevated by blood and that the internal limiting membrane of the retina was intact and in its normal position. In two chronic cases, a dome-shaped epiretinal membrane was excised from the macula during vitrectomy. Light and ultrastructural studies demonstrated that the membranes consisted of glial cells and basement membrane material. The dome-shaped structure observed in eyes with Terson's syndrome is due to the formation of a subhyaloid hemorrhage. The partially detached posterior hyaloid face created by this hemorrhage provides a scaffold for cellular proliferation and the development of an elevated epiretinal membrane in long-standing cases. Echographically, this membrane resembles a retinal detachment in B-scans, but can be clearly distinguished from retina with standardized A-scan.

Adult↗
PubMed1986

Fatty acid composition and arachidonic acid metabolism in vitreous lipids from canine and human eyes.

About 55% of the acyl groups of dog and human vitreous are unsaturated fatty acids. The major components are oleate (18:1, n-9) and arachidonate (20:4, n-6) with moderate amounts of linoleate (18:2, n-6) and docosahexaenoate (22:6, n-3). Palmitate (16:0) and stearate (18:0) are the major saturated fatty acids. There are no significant changes between ages 37-82 years in the fatty acyl group content and composition of human vitreous. In vitreous from Irish setters with hereditary rod-cone dysplasia (RCD) the levels of oleate are decreased with a concomitant increase in arachidonate. [1-14C]Arachidonic acid was actively incorporated into canine vitreous glycerolipids both in vitro and in vivo. The incorporation was mainly into phosphatidylinositol, triacylglycerol, phosphatidylcholine and phosphatidylethanolamine. There were some differences in the pattern of incorporation between human and dog and between in vivo and in vitro incubations of canine vitreous. Glycerolipid acylation was significantly increased in phosphatidylinositol and phosphatidylcholine in RCD canine vitreous. The pattern of incorporation of [U-14C]docosahexaenoic acid into vitreous glycerolipids was different from arachidonic acid incorporation. Although vitreous did not produce any measurable enzymatic synthesis of cyclooxygenase and lipoxygenase products from [1-14C]-arachidonic acid in vitro, there was significant generation of autooxidation products. These results suggest an active lipid metabolism in vitreous.

Animals↗
PubMed1986

Sodium hyaluronate (Healon) in closed vitrectomy.

Healon was implanted into the vitreous cavity of 33 eyes at the conclusion of pars plana vitrectomy. In aphakic eyes, Healon diffused rapidly into the anterior chamber, reducing the length of effective tamponade posteriorly and causing marked elevations of intraocular pressure. In phakic diabetic eyes, Healon appeared to trap hemorrhage mechanically from bleeding fibrovascular stumps posteriorly. It may therefore reduce the risk of opacifying vitreous hemorrhage after vitrectomy in phakic eyes with active neovascularization.

Humans↗