Biomedical subjects

U Giers

Publications and source records attributed to U Giers.

10 recordsLinked to original sources

PubMed1992

[Oculopression tonometry after argon laser trabeculoplasty].

A group of 26 patients (14 female and 12 male ranging in age from 49 to 84 years) who had primary open angle glaucoma underwent argon laser trabeculoplasty in one eye each. Shortly before the laser treatment, and one and twelve (7-14) weeks after the treatment suction cup oculopression tonometry was performed with an increase of intraocular pressure according to 1.8 x actual intraocular pressure. A therapeutically significant decrease of intraocular pressure was observed already one week thereafter, but findings become more significant after a longer follow up. The decrease of intraocular pressure and results of oculopression tonometry indicate that the measured resistance to aqueous outflow decreased significantly after argon laser trabeculotomy.

Aged↗

PubMed1991

[Iris fluorescence angiography findings in oculo-oscillodynamography].

Supported by irisfluorescein angiography it should be examined if systolic ciliary pressure found by oculooscillodynamography is to be seen in every part of the uvea. Iris vessels were found to be perfused at 42 mm Hg (Median, Q1-Q3 = 38-45 mm Hg) whereas oculooscillodynamography displayed systolic ciliary pressure to be 69 mm Hg (62-72 mm Hg). This different blood pressure in different districts of the uvea may be one explanation for the particular vulnerability of iris vessels e.g. in ischemic ophthalmopathy.

Adult↗

PubMed1991

[Changes in postoperative corneal astigmatism after laser dissection of corneo-scleral sutures].

In a group of 68 consecutive cases of high surgically induced corneal astigmatism following extracapsular cataract extraction or phacoemulsification, single limbal sutures were released by argon laser. Visual acuity and refractive results 2-6 weeks after treatment were compared to those before laser application. The effect of suture dissection was analyzed according to the number of sutures released, the follow-up time from cataract surgery and previous corneal astigmatism. The effect of suture dissection was not dependent on the interval from surgery up to 20 weeks postoperatively. The reduction in astigmatism amounts 2.25 dptr up to 8 weeks, occasionally 2.5 dptr 8-10 and 11-16 weeks after surgery, and 1.75 dptr up to 20 weeks thereafter (mean values). The longer the interval the more sutures had to be released. If only one suture was dissected, the reduction in astigmatism amounted 1.75 dptr (mean), if two sutures were released the effect was 2.5 dptr, three or more dissected sutures lead to a 3.4-dptr reduction in corneal astigmatism. The axis of astigmatism did not change in 52 of 59 cases, but in some subjects oblique astigmatism appeared after suture dissection.

Astigmatism↗

PubMed1990

Comparison of A-scan device accuracy.

A-scan biometry is recognized as a useful aid in predicting intraocular lens power. Measurements are reported to be accurate to better than +/- 0.1 mm. Three biometry devices were compared in examinations of 159 persons, each examination being repeated several times. Axial length averaged 23.77 mm when measured by the immersion technique; applanation and modified applanation techniques yielded 0.1 mm and 0.3 mm shorter distances, respectively. Measured values of axial lengths did not have the same probability of being measured, even if they were close together. Results were not distributed in smooth Gaussian curves; on the contrary, clusters of values, on the pattern of our choice of ultrasound wavelength, were seen even when biometry was performed with electronic gates in the devices. Retest reliability decreased when short distances in the anterior segment of the eye were measured. Measurements of lens thickness were less readily reproducible in cataractous lenses than in healthy young eyes; anterior chamber depth, on the other hand, was measured more reliably in cataract patients. This last finding may have resulted in part from uncertainties about ultrasound velocity in the cataractous lens and in part from accommodation. In cataract patients, axial length was measured most reproducibly by the immersion technique; it was measured less accurately in young healthy eyes with a modified applanation device.

Adolescent↗

PubMed1990

[The reliability of ultrasound biometry].

Preoperative ultrasonic biometry is indispensible in cataract surgery in order to calculate the power of the intraocular lens to be implanted. Various authors have suggested that the accuracy of the measurements could be improved by performing biometry several times and basing the calculation of the lens on the mean value. The problem of the retest reliability of ultrasonic measurements was investigated in 99 young subjects with healthy eyes and 60 cataract patients. Biometry was performed three times consecutively in each mode using three different scanners and different coupling techniques. A comparison of the consecutive measurements showed good agreement (between r = 0.96 and r = 0.99) in regard to axial length and hence very good retest reliability. The accuracy of the repeat measurements was approximately the same with all three coupling methods used. The correlation coefficients of retest measurements of anterior chamber depth and lens thickness were much lower (r = 0.78 to r = 0.96). This may be explained by differences in handling of the probes, in the test modes, and in the physical conditions on which the measurements are based. In view of the good reproducibility of axial length measurements the authors consider one carefully performed biometry more valuable for preoperative calculation of lens power than the mean of several measurements.

Adult↗

PubMed1990

[Suction cup ocular pressure versus Vörösmarthy oculopression. Biometry differences].

In a 20-min follow-up after oculopression, biometric measurements were taken before, immediately after, and 5, 10, 15 and 20 min after finishing oculopression. Thirty-two eyes were measured by ultrasound using the immersion technique with a 10 MHz A-scan probe. Sixteen cataract patients more than 50 years of age and 16 healthy young subjects up to 30 years of age took part in the study. Oculopression was performed either with a Honan Oculopressor or with a Mikuni and Yoneyama suction-cup oculodynamometer. The anterior chamber depth showed higher initial deepening following Honan oculopression, whereas the length of the vitreous was found to be shorter with the same method. Suction-cup oculopression revealed no distinct changes in these compartments. Nevertheless, 10 min after oculopression, there was no statistically significant difference between the two oculopression techniques. When comparing the age groups, the cataract patients showed more express change than the younger subjects.

Adult↗

PubMed1989

[The effect of lens haptics on postoperative anterior chamber depth in PMMA posterior chamber lenses].

In two groups of patients with two different posterior chamber intraocular lenses, very different correlations were found between postoperative and calculated anterior chamber depth, and between postoperative anterior chamber depth and axial length. Since it has long been known that there are positive correlations between anterior chamber depth and axial length in phakic patients, while on the other hand (according to many authors) these correlations seem to disappear in pseudophakic patients, and since the present authors found these positive correlations only in patients with one type of implant, they ascribe these differences between similar implants to the geometric configurations of the lens loops. In lenses with modified J-loop designs the optical zone might be dislocated backward when the lens is compressed, while lenses with C-shaped seem to suffer only minimal dislocation or none at all. The importance of this phenomenon in relation to individually different diameters of the eye and different localizations of lens loops, depending on implant technique, are discussed.

Anterior Chamber↗

PubMed1989

[Flattening of the anterior chamber and myopic results in sulcus fixation of posterior chamber lenses].

Ultrasonographic biometry was performed in 56 patients immediately after implantation of a posterior chamber intraocular lens to measure the position of the lens. A modified applanation method was used to avoid injury to the scleral suture. Ten months later, 44 of these patients were examined by the same method. The anterior chamber depth was found to have decreased from 4.26 mm (s = 0.39 mm) in the immediate postoperative period to 4.2 mm ten months later. However, axial length, at 23.28 mm postoperatively and 23.34 mm at follow-up, and mean corneal refraction (43.28 D and 43.34 D, respectively) were practically unchanged. There was a shift in the spheric equivalent of refraction from postoperative emmetropia (mean -0.07 D) to slight myopia (mean -0.76 D) at follow-up. This mean myopization of 0.69 D corresponded to the tendency toward a shallower anterior chamber. Shrinkage and fibrosis of the posterior capsule, reduced elasticity of the polypropylene loops, flattening of the cornea and axial changes are discussed as possible causes. The tendency toward myopization should be taken into account when calculating the power of sulcus-fixated posterior chamber lenses.

Anterior Chamber↗

PubMed1981

p-Chlorophenylalanine-induced proliferation of the seminal vesicle epithelium.

Intraperitoneal injection of p-chlorophenylalanine (pCPA) methylester (100 mg/kg body weight) results in an activation of the lysosomal system of the secretory cells in the rat seminal vesicle and an elevation of the activities of lysosomal enzymes within 15 min following the injection. Large autophagic vacuoles are formed, sequestering rough endoplasmic reticulum and part of the Golgi apparatus within 2 h. Shortly after the activation of the lysosomal system an elevation of both DNA- and protein synthesis is measured biochemically. 6 h subsequent to the injection a wave o mitoses of the secretory cells begins, reaching a maximum of 6 h later and then declining within 3 h. About 12 h following the injection a second rise in lysosomal activity begins, declining within 24 h. The entire sequence of lysosomal and proliferative activities is inhibited in antiandrogen-pretreated rats. Deduced from these findings the following hypothesis of growth regulation of the accessory sex glands is advanced: enhanced loss of intracellular material during autophagocytosis diminishes the intracellular concentration of a substance curtailing cell division below its effective threshold resulting in division of the secretory cells. The prerequisites of this mechanism are (i) a sufficient distributive capacity of the stroma for hormones (androgens) and metabolic precursors, and (ii) sufficient capacity of the basal cells for transporting the precursors to the secretory cells. Sloughing of the secretory cells separates them from these auxiliary structures (stroma and basal cells) and enables the basal cells to divide.

Animals↗

PubMed1980

Fine structure of the Sertoli cells of the rat testis in experimental unilateral cryptorchidism.

Mature rats were made unilaterally cryptorchid for 28 days. ABP concentrations of the abdominal epididymis were significantly reduced, indicating impaired secretory activity of the Sertoli cells. The FSH serum level was increased and testosterone levels both of the serum and of homogenates of the cryptorchid testis were slightly reduced. Sertoli cells of the cryptorchid testis showed signs of regression. Although Sertoli cell junctions were still impermeable to lanthanum, a reduction of membrane particles forming the Sertoli cell junctions was observed in freeze-fracture replicas. In thin sections it was seen that the plasma membrane-apposed cisternae of endoplasmic reticulum or the adjaacent microfilaments were partially lacking. No such changes were observed in the scrotal testis.

Animals↗