Search PubMed⌕ Search

Biomedical subjects

T R Friberg

Publications and source records attributed to T R Friberg.

At least 73 records · Page 4Linked to original sources
PubMed1985

Angiotensin-converting enzyme activity in human aqueous humor.

We measured aqueous angiotensin-converting enzyme (ACE) activity in 37 patients. Patients with granulomatous uveitis and probable sarcoidosis (based on increased serum ACE activity or characteristic radiologic findings) had a significant increase in aqueous ACE activity compared with normal subjects. Aqueous ACE activity was also significantly elevated in patients with sarcoid who had normal serum ACE activity. We believe that measurement of aqueous ACE activity should be considered in patients with uveitis who have normal serum ACE activity and are suspected of having sarcoidosis.

Adult↗
PubMed1985

Optic nerve dysfunction during gravity inversion. Pattern reversal visual evoked potentials.

The intraocular pressure (IOP) in humans approximately doubles when a head-down, or inverted, position is assumed. Simultaneously, the ophthalmic artery pressure increases by an even greater absolute magnitude. We recorded pattern reversal visual evoked potentials (PRVEPs) in 16 subjects in both the inverted and upright positions. In ten of the 16 subjects, we performed an additional experiment. On a different day, we obtained control PRVEPs, and then, using a scleral suction cup, we artificially increased the IOPs to the same values reached when the subjects were previously inverted. We found that the PRVEP amplitudes were significantly reduced in both experiments compared with corresponding control recordings, without changes in latency or wave form. Furthermore, the degree of amplitude reduction was even greater during gravity inversion than with suction cup elevation of IOP. The effects of IOP on optic nerve function as measured by the PRVEP appear to be dependent more on the IOP than on vascular perfusion. We also concluded that gravity inversion activities pose potential risks to the eyes.

Adult↗
PubMed1985

The effect of long-term near normal glycemic control on mild diabetic retinopathy.

Thirty-three type l diabetics who used continuous subcutaneous infusion of insulin (CSll) and 24 diabetics on conventional treatment (maximum of two injections per day) were studied prospectively with ophthalmologic examinations, fundus photography, fluorescein angiography, and glycosylated hemoglobin (HbA1) determinations. Both groups were similar with respect to age, duration of diabetes, and length of follow-up. At entry almost all patients had only mild forms of diabetic retinopathy although three CSll patients had early proliferative retinopathy. The CSll groups achieved superior glycemic control throughout the study (mean HbA1 = 7.4% vs. 10.2%). After an average follow-up of more than 30 months, the CSll group showed significantly less progression of diabetic retinopathy as measured by macular aneurysm counts and by modified ETDRS grading. Careful control of glycemia may delay the progression of diabetic retinopathy.

Adolescent↗
PubMed1984

Effect of inverted body position on intraocular pressure.

We evaluated changes in intraocular pressure in eyes with primary open-angle glaucoma after inversion into a totally dependent position with the head down and compared them with the changes intraocular pressure in healthy nonglaucomatous eyes. Five minutes after inversion, intraocular pressure increased from 16.8 mm Hg +/- 2.8 (sitting) to 32.9 mm Hg +/- 7.9 in normal eyes and from 21.3 mm Hg +/- 2.3 (sitting) to 37.6 mm Hg +/- 5.0 in glaucomatous eyes. Although visual fields were unchanged after inversion, glaucomatous eyes may be particularly susceptible to such changes and unable to withstand the transient but significant increase in intraocular pressure that occurs after assuming an inverted position. We recommend that patients with ocular hypertension or glaucoma refrain from this activity.

Adult↗
PubMed1984

Intravitreal ceftriaxone in a rabbit model. Dose- and time-dependent toxic effects and pharmacokinetic analysis.

Ceftriaxone's toxic effects were assessed in albino rabbits after intravitreal injection. Doses up to 5 mg did not alter the B-wave amplitude. Following 7.5-and 20-mg doses, B-wave amplitude ratios were depressed at 24 hours and normal at seven and 14 days. A 50-mg dose caused a temporarily flat B-wave 24 hours after injection. At two weeks this ratio exhibited a moderate increase but remained 2 SDs below the mean preinjection ratio. Eyes receiving up to 20 mg were normal histologically at 14 days. A 50-mg dose induced generalized retinal edema and disruption of the retinal layers 24 hours after injection; at two weeks there were no histologic changes in the retina. Immediately after a 2-mg intravitreal injection, vitreous ceftriaxone levels were 1,345 +/- 4.9 mg/L; by 72 hours they had decreased to 17.6 +/- 1.4 mg/L. The mean peak aqueous level was 80.2 +/- 12.2 mg/L at 72 hours.

Animals↗
PubMed1984

The effect of vitreous and retinal surgery on corneal endothelial cell density.

The effect of vitreoretinal surgery on corneal endothelial cell density was studied prospectively in 69 eyes by comparing preoperative endothelial cell densities to postoperative data. The mean cell loss in eyes of diabetic patients did not differ significantly from those of non-diabetics. The mean endothelial cell loss in 30 phakic eyes which underwent pars plana vitrectomy without lens removal was 1.3 +/- 1.4%. In aphakic eyes, vitrectomy and scleral buckling led to a mean cell loss of 12.6 +/- 2.3%. When vitrectomy was combined with lentectomy and scleral buckling, the mean cell loss was 8.5 +/- 1.8%, but eyes undergoing fluid-gas exchange in addition to these procedures suffered a mean cell loss of 16.9 +/- 1.9%. The presence of the lens protects the corneal endothelium during pars plana vitrectomy, while fluid-gas exchange in aphakic eyes appears to have a detrimental effect.

Cell Count↗
PubMed1983

Penetration of topical indomethacin into phakic and aphakic rabbit eyes.

The penetration of indomethacin labeled with radioactive carbon (14C) into all ocular tissues and fluids was determined at various intervals in both phakic and aphakic rabbit eyes after either single or multiple (every 12 hours for three days) topical application (50 microL) regimens. More indomethacin was found in the vitreous of aphakic eyes compared with phakic eyes after single- or multiple-drop administration. Retinal and choroidal indomethacin concentrations were equal in both phakic and aphakic eyes after either drug regimen and are much greater than those of the vitreous. A pathway other than diffusion through the vitreous exists for the drug to reach these tissues. The concentration of indomethacin reaching the retina and choroid is not sufficient to inhibit prostaglandin formation locally. The concentrations of indomethacin are high enough to inhibit the biotransformation of prostaglandin precursor only in the anterior segment.

Administration, Topical↗
PubMed1983

Choroidal folds and refractive errors associated with orbital tumors. An analysis.

Twenty patients with unilateral exophthalmos secondary to orbital tumors underwent fundus photography; 16 underwent fluorescein angiography. Choroidal folds were found in 15 eyes. The location of each tumor with respect to the globe was determined by computed tomography. In addition, most patients underwent B-scan ultrasonography and surgical exploratory procedures. Choroidal folds were more common in patients with greater amounts of exophthalmos and with anteriorly located tumors. Moreover, the pattern of choroidal folds generally reflected the location of the tumor within the orbit. Comparison with the uninvolved fellow eyes showed that preoperative refractive errors were usually shifted toward hyperopia with intraconal tumors, whereas extraconal tumors were typically associated with higher astigmatic errors on the involved side.

Diagnosis, Differential↗
PubMed1983

Extremely rapid growth of a primary choroidal melanoma.

A small, minimally elevated, nonpigmented choroidal tumor increased in volume 12-fold and grew from the edge of the fovea to the optic disk within 60 days. Histopathology of the enucleated globe demonstrated a mixed spindle and epithelioid cell malignant melanoma with numerous mitotic figures. The calculated doubling time of this tumor was 17 days.

Choroid Neoplasms↗
PubMed1983

Hepatitis B surface antigen in human subretinal fluid.

Body fluids containing hepatitis B surface antigen are considered to be potential sources of hepatitis B infection. This antigen has been detected in blood, oral secretions, synovial fluid, urine, feces, bile cerebrospinal fluid, pleural and peritoneal fluid, semen, vaginal secretions, breast milk, and tears. These fluids are probably not equally infectious, however, because the concentration of virus in a particular fluid may be low when compared to that in blood. For instance, in hepatitis B carriers whose tears were positive for hepatitis B surface antigen, the concentration of hepatitis B surface antigen in the tears averaged less than one-fifteenth the average value found in serum.

Adult↗
PubMed1982

Endophthalmitis after strabismus surgery.

We treated two cases of endophthalmitis caused by strabismus surgery. In one patient, a scleral perforation was recognized during surgery and treated with cryopexy. In the other, a scleral perforation was suspected but never confirmed. Despite intensive antibiotic and corticosteroid therapy, visual acuity decreased to light perception in Case 1 and to counting fingers in Case 2. The second eye was enucleated eight years later after it had become blind and painful.

Adolescent↗