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Biomedical subjects

E Krogh

Publications and source records attributed to E Krogh.

At least 37 records · Page 2Linked to original sources
PubMed1983

Prognostic parameters in pars plana vitrectomy.

Based on a period of introduction with the vitrectomy technic the visual acuity results in 143 consecutive cases performed between 1976 and 1980 are related to the anamnestic information, the pre-, per- and post-operative findings. In this introductional period the patients referred had longstanding retinovitreal changes, and, because of lack of prognostic parameters, all patients were offered surgery regardless of the observed pathology. All vitrectomies were carried out with the Klöti macrostripper and diathermy unit, without any additional instrumentation. From the results of these early cases, we have changed our surgical method to a three-port entrance with a separate infusion canula, a separate fiberoptic illumination and an interchange between vitrector, automatic scissors, hook, stilleto, vacuo needle, forceps and intravitreous photocoagulation through a third port. Diabetics should be offered vitrectomy if vitreous haemorrhages last for more than 3 months. Vitrectomy is considered useless or contraindicated in diabetics with lack of light perception or light projection, neovascular glaucoma, extinguished visual evoked potential. Only an improvement in the peripheral vision can be expected in diabetics with macular detachment. In rhegmatogenous detachment cases with intravitreal traction, vitreous operations should be performed only where intraretinal or retroretinal changes do not prevent mobilization or unfolding of the retina. Traumatic vitreoretinal disorders should be operated upon early.

Adolescent↗
PubMed1981

Reversible colour vision defects in obstructive jaundice.

The ocular function of 14 non-alcoholic, high icteric patients with recent occlusion of the common bile duct and 3 patients with viral hepatitis with a cholestatic pattern was studied. By means of a colour vision test panel including the Farnsworth-Munsell 100-hue test, 12 patients were initially classified as colour defective with a pattern of acquired colour vision deficiency (ACVD), predominantly of a tritan type. Visual acuity, visual field, slit lamp microscopy, intraocular pressure, ophthalmoscopy and tear secretion tests were normal, and all patients had normal levels of serum vitamin A. Retesting of 4 initially colour defective patients after disappearance of the obstructive jaundice showed a complete normalisation of the ACVD's. It is concluded, that the colour perception in patients with obstructive jaundice is related to the serum bilirubin level, and not to a deficiency of vitamin A.

Adult↗
PubMed1980

VER in intraocular hypertension. Short communication.

Transient and steady state VER's before and after artificial IOP elevation were recorded from 16 eyes (9 persons) with untreated intraocular hypertension observed for several years without signs of functional loss or optic disc changes. Four eyes (two patients) demonstrated a pathological transient VER amplitude drop after pressure increase. One eye with an ophthalmoscopically atypical disc presented a grossly deformed transient VER at the habitual pressure level; the fellow eye was lost from trauma. Another eye presented an abnormal VER pattern and showed as yet normal function and ophthalmoscopy, the fellow eye had developed open angle glaucoma and showed identical VER changes. The prognostic and diagnostic implications are briefly discussed.

Adult↗
PubMed1977

Normal values in clinical electrooculography. III. Numerical evaluation of two dimensionless EOG parameters.

The distribution of the Arden ratio (A) and another dimensionless EOG quantity (G) devised by Gliem (1971) in a sample of normal human subjects are presented. The minimum, median and maximum values for A are 148--241--449 and for G 34-88-167. A demonstrates a smaller degree of dispersion than G, the latter resembling in this respect the EOG potential parameters of the same sample. The average accumulation of errors due to inaccurate assessment of the included potential figures is almost equal in the functions of A and G. Divergencies between the figures from the present and earlier investigations are discussed together with the general advantage of dimensionless EOG parameters. It is concluded that the present investigation has not demonstrated the need to replace or supplement the Arden ratio by the Gliem quantity.

Adolescent↗
PubMed1977

Normal values in clinical electrooculography. V. Variability within and between eyes.

Three EOG's (DC amplified 30-degree saccades, slightly modified Arden schedule) were recorded at weekly intervals from each of 16 normal human eyes (eight subjects). The light induced potential rise of the dark-adapted eye, the Arden ratio and the Gliem ratio entered into the analysis of intra- and inter-eye variation. The 95% confidence intervals for the mean parameter values of each eye were: +/- 59 muV (mean = 415 muV) for the light induced potential rise, +/- 22 (mean = 260) for the Arden ratio and +/- 10 (mean = 92) for the Gliem ratio. The intra-eye variability was compared to earlier studies of the day-to-day variation of the ERG by means of a dimensionless index; no substantial differences were found. Highly significant differences in the EOG parameter levels existed between the subjects, whereas the variation between right eye and left eye means in the individual subjects was ise respects. The primarily qualitative nature of the EOG in the present version is emphasized by the present results.

Adult↗
PubMed1977

Ocular function in cirrhosis of the liver.

The ocular state of 28 ascertained non-alcoholic females with cirrhosis of the liver was assessed. Only twenty were able to go through the complete colour vision test, and among these, three patients (one without, and two with increased level of serum bilirubin) with acquired colour vision defects were observed. Visual acuity, visual field, intraocular pressure, binocular function, slit lamp microscopy, ophthalmoscopy and tear production were normal in all cases. It is concluded that the frequency of colour vision defects in the present sample is increased, and that alcohol abuse is not a prerequisite for colour vision defects in patients with cirrhosis.

Adolescent↗
PubMed1977

Normal values in clinical electrooculography. IV. Analysis of two dimensionless EOG parameters and their relation to other variables.

Two EOG parameters - The Arden ratio (A) and an expression devised by Gliem (G) - from a sample of normal human subjects are studied. Their relations to the EOG potential and time parameters and to sex, age, pupillary diameter, degree of iris pigmentation, refractive error and axial length, ocular protrusion and interpupillary distance were assessed. Right eye and left eye distributions were congruent, although individual differences were sometimes appreciable, especially in the case of G. The two ratios were positively correlated and both showed a negative correlation to the interval between the dark trough and the light peak. Correlations to the EOG potential parameters, especially the light induced potential rise of the dark adapted eye, were also established. In the case of A, a higher level was disclosed in the male half of the sample. A negative age correlation, predominant in the female part of the sample, characterized both ratios. The two ratios were positively correlated to the pupil diameter, negatively correlated to the degree of refractive errror, and positively correlated to the degree of ocular protrusion. The consequences for the clinical EOG test are discussed, and it is concluded that the present EOG procedure is a qualitative rather than a quantitative test.

Adolescent↗
PubMed1976

Normal values in clinical electrooculography. II. Analysis of potential and time parameters and their relation to other variables.

The following EOG potential and time parameters from 72 normal subjects were analysed: base value B, dark trough D, light peak L, light induced potential rise L-D, interval between beginning of dark adaptation and occurrence of dark through d and interval between dark trough and light peak l. Their relations to sex, age pupillary diameter, degree of iris pigmentation, refractive error, axial length, corneal curvature and diameter, ocular protrusion and interpupillary distance were assessed. Right eye and left eye samples of the EOG parameters were congruent, although individual differences were sometimes appreciable. The levels of B and D were higher in the female half of the sample. A positive correlation existed between age and D level. L-D was negatively correlated to the degree of refractive error and positively correlated to the ocular protrusion. A positive correlation was found between d and the four potential parameters, and there was a positive correlation between age and l. Practical consequences of the statistical analysis relating to the interpretation of such EOG data are discussed.

Action Potentials↗
PubMed1975

DC recording of the human corneofundal potential.

The limitation of an AC technique for the amplification and display of the indirectly recorded human corneofundal potential (CFP)is discussed. A Mingograph M34 with EMT 12 B preamplifiers (Siemens) has been tested with regard to a DC recording of the CFP. With the same purpose the electrical characteristics of two electrode types--a Kaiser lead alloy electrode and a Beckman silver-silver chloride cupped electrode--were examined and a suitable preparation of the skin contact area indicated. Finally the base line stability was evaluated and a comparative study of AC and DC recordings of the CFP presented and subjected to statistical anaylsis.

Cornea↗
PubMed1975

Normal values in clinical electrooculography. 1. Material, method, methodological investigations and distribution of the potential and time parameters.

For the evaluation of normal EOG potential and time parameters a case series (142 eyes) is presented. An EOG technique aiming at the largest possible amplitude between the dark trough and the light peak is described. It is shown that the light-induced response following a 20 min period of adaptation to a very low degree of illumination (about 1/10 lx, allowing a rough orientation on the displayed trace) does not differ from that produced after 20 min of total darkness. Also, the independence of the pupillary area for the light-induced response is demonstrated, which means that the light stimulus employed (2500-4000 lx) is supramaximal. Furthermore, the good quality of the gaze fixation in the actual test situation with respect to the recording of equidistant saccades is proven. A DC amplification of the signal is used, which secures independency of inter- and intra-individual differences in the saccadic velocity and makes possible accurate measurements of deflections disfigured by correcting movements. The following EOG parameters are recorded: A base value after 10 min of preadaptation with the light stimulus, the dark trough and the light peak potentials. Also the periods between the beginning of the dark adaptation and the dark trough and between the dark trough and the light peak are noted. The frequency distribution and the general level of the various parameters are discussed in the light of comparable figures of previous publications.

Adaptation, Ocular↗