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Biomedical subjects

P Hendrickson

Publications and source records attributed to P Hendrickson.

51 records · Page 3Linked to original sources
PubMed1978

An injection/circulation-timing switch for angiography.

An injection/circulation-timing switch was developed to simply and precisely initiate the timing unit of the fundus camera for angiographic documentation. After starting the timer, the switch, mounted on the syringe used for injection of the tracer material, subsequently provides documentation of the total elapsed time of injection. Such quantitative data can enhance the evaluation of angiographic results and contribute to their universal comparability when combined with such qualitative data as injection location and total injectate.

Fluorescein Angiography↗
PubMed1977

[Improved method of lens photograpy using retroillumination (author's transl].

Lens photography with a fundus camera using retroillumination is suited for long term follow-ups of senile cataract development. An improved method using a 9 grade colour standard is presented, which makes a comparative evaluation of the colour of the fundus reflex possible. A colour filter effect of the lens nucleus in nuclear sclerosis can thus be evaluated.

Aged↗
PubMed1976

[Experimental fluorescein angiographic and microscopic investigations on laser treated rat eyes (author's transl)].

On fundi of pigmented rats, with Argon laser constantly 300 mW of power. 2 seconds exposure time and 50 microns spot diameter, coagulations have been performed. The eyes have been observed up till 3 months after the intervention, then angiographies were performed, and the following enucleated eyes have been examined with the fluorescence microscope. Neovascularizations and dye diffusions were observable mainly in the marginal zones of the arised cicatrices. The neovascularizations were starting from the choroid and penetrating into the outer retinal layers.

Animals↗
PubMed1976

Observation of injected fluorescein diffusion after laser treatment of cat fundi. An experimental study with angiography and microscopy.

Argon laser coagulations with a power of 100 mW and 300 mW, exposure time 0.02 and 0.02 sec, and constant spot size of 100 microns were applied on normal cat fundi. From 1 and 2 hrs to 7 days after the coagulation, the treated eyes were observed angiographically and by fluorescence microscopy after dye injection; freeze dried eyes were examined under a fluorescence microscope. Abnormal dye leakages originated from the chorid and from retinal vessels were detected in the specimens examined within 72 hrs after the coagulation.

Animals↗
PubMed1975

Iris angiography in cystoid macular edema after cataract extraction.

Iris angiography was performed on eight patients (nine eyes), who had cystoid macular edema postcataract extraction. The fundus fluorescein angiographies showed typical star-shaped, multiloculated staining of the macular area. The iris angiographies demonstrated moderate to massive leakage of dye from the iris, and possibly leakage of ciliary body vessels into the anterior chamber, thus evidencing the until now suspected but undocumented fact that fluorescein leakage is not restricted to the fundus vessels. These data tend to support the idea that this type of macular edema is due to a vascular abnormality, and not to altered vitreous mechanics.

Aged↗
PubMed1975

Provoked iris ischaemia in the rabbit: A fluorescien angiographic study.

We studied experimental anterior segment ischaemia in rabbits by fluorescein angiography of the iris. Nine rabbits were subjected to diathermy occlusion of one or both long posterior ciliary arteries or to disinsertion and reattachment of up to 4 rectus muscles. Occlusion of one LPCA or up to 3 recti had only a minor ischaemic effect on the iris vessels. Occlusion of both LPCAs produced necrosis of the anterior segment or ischaemia of the iris detectable by angiography. Disinsertion of 4 recti produced small patches of transient ischaemia in those areas of the iris most distal from the LPCAs. When further surgery is planned after retinal detachment cyclodiathermy or strabismus operations, fluorescein angiography is a useful indicator of the vascular status of the iris and hence of the possibility of necrosis of the anterior segment.

Animals↗
PubMed1975

[Monitoring the progress of lens opacities in cases of senile cataract by retro-illumination photography (author's transl)].

A follow-up study of lens opacities, utilizing retro-illumination photography with the fundus camera is described. After giving technical details, results are discussed and possible errors pointed out. If evaluation by planimetry or other devices is not possible, a useful procedure is the evaluation of simultaneous projected slides by a group of ophthalmologists not directly involved in the trial. This is demonstrated by testing the effect of 1-hydroxy-pyrido-(3,2alpha)-5-phenoxazone-3-carboxylic acid on the progress of senile cataract in a total of 48 eyes. Together with slit image photography of Brown (2, 3) the method of retro-illumination photography of the lens presented in this paper is a definite improvement in demonstrating the temporal course of cataract development.

Aged↗
PubMed1975

[Experimental fluorescence angiographic and microscopic investigations on laser treated animal eyes (author's transl)].

The effects of laser coagulation on rat fundi were studied angiographically and with the fluorescence microscope. The coagulations were performed using constantly 300 mW and 0.2 second exposure time and 50 microns spot diameter. We observed the animals for 3 months, after which we could still observe dye diffusion by fluorescence angiography. With the fluorescence microscope we could localize these diffusions as originating from neovascularisation starting from the choroid. These new vessels penetrated subsequently into the exterior retinal layers. At the beginning of our observation time, the retinal vessels showed some sinuosities, dilatations and solitary stenosis, but no disturbance of circulation was demonstrable.

Animals↗
PubMedDate not supplied

Influence of nifedipine on the visual fields of patients with optic-nerve-head diseases.

Calcium-channel blockers have long been employed in coronary disease, and recent investigations have indicated their efficacy in improving the visual field in low-tension glaucoma or presumed vasospasm, possibly by enhancing ocular circulation. We evaluated the short-term influence of a typical calcium-channel blocker, nifedipine, on 59 patients with visual-field defects, some with optic-nerve-head pathology (n = 38) and some with normal-appearing optic nerve heads (n = 21). On the average, a statistically significant improvement of 1.2 dB was observed. Different types of patients, however, behaved quite differently. The younger the patient, the greater the improvement. Patients with normal optic nerve heads improved by 1.54 dB, whereas patients with optic-nerve-head excavation improved by only 0.66 dB. No response was observed in patients with anterior ischemic neuropathy. Marked deterioration was noted in one glaucoma patient with low systemic blood pressure. The visual-field changes were observed in the scotomatous and non-scotomatous areas. Thus, the calcium-channel blocker nifedipine can be effective in some selected diseases whose pathogenesis probably involves vascular dysregulation though it may even be contraindicated in others.

Glaucoma↗
PubMedDate not supplied

Evaluation of the Brusini glaucoma staging system for follow-up in glaucoma.

BACKGROUND: Brusini developed a new interpretation system for Octopus and Humphrey automated perimeters that is based on mean defect (MD) and corrected loss variance (CLV) or corrected pattern standard deviation (CPSD). This study tested the performance of Brusini's glaucoma staging system (GSS) in staging and follow-up. METHODS: Retrospectively, 610 visual fields of 64 eyes of open-angle glaucoma patients were analyzed with Brusini GSS and compared with Aulhorn-Karmeyer stages and by PeriData 7.0 trend analysis. RESULTS: Follow-up was comparable to PeriData 7.0 trend analysis in 97%. Change was observed in 41% of eyes, i.e., initial improvement (19% eyes), deterioration (16%), and after an initial improvement, either deterioration (11%) or a stable period (5%). No change was seen in 59% of the eyes, of which 30% showed small and 19% high long-term fluctuation (LF) due to fatigue effect, poor cooperation of patient, impaired reliability, or short-term fluctuation (SF) greater than 1.7 dB. However, for 8% of the eyes there was no apparent reason for high LF. CONCLUSIONS: Brusini GSS is useful for staging and recommended for follow-up evaluation of visual fields in glaucoma.

Aged↗
PubMedDate not supplied

Heidelberg retina flowmeter parameters at the papilla in healthy subjects.

PURPOSE: To assess the Heidelberg Retina Flowmeter (HRF) parameters "volume", "flow", and "velocity", at the papilla in healthy subjects. METHODS: HRF measurements were taken at the papilla (5 degrees x 20 degrees), superficially at level of the retina and at the bottom of the excavation. The effect of increasing frame size (1 x 1 to 50 x 50 pixels) on HRF values was assessed in ten subjects. HRF parameters were calculated (50 x 50 pixels) for 150 eyes of 150 subjects. To assess short-term reliability, measurements were repeated five times in ten subjects. RESULTS: With 50 x 50 pixels the location of the frame had no influence on HRF values. Reliability was > 90%. Values were significantly higher (p < 0.001) in the superficial than in the deeper papillary layers. The correlation between HRF parameters was good (r2 > 0.85). CONCLUSIONS: A low magnification (5 degrees x 20 degrees) and a 50 x 50 frame allows a global assessment of HRF parameters at the papilla with high reliability. In healthy eyes, the HRF values are influenced by the level where measurements are made at the papilla. This might be of importance in glaucoma patients with excavated papilla.

Blood Flow Velocity↗