Biomedical subjects

H Wassill

Publications and source records attributed to H Wassill.

3 recordsLinked to original sources

PubMed1999

Critical perimetry - functioning methods.

Visual field defects without any organic correlate require critical control to avoid inadequate management of psychogenic defects. Which methods are promising to detect psychogenic visual field defects? Twenty ophthalmologically trained volunteers motivated to pretend a concentric visual field loss were tested by manual perimetry with centripetal and centrifugal movement of the stimulus, by evoking saccadic eye movements towards a stimulus outside the subjectively claimed visual field and by observation of the volunteers' strategy searching a stimulus beyond the subjectively claimed borders. Malingering could be proven in 16 persons. The most favourable procedure is to evoke eye movements towards a peripheral stimulus. These movements yield information about the visual field outside the subjectively stated limits.

Adult↗

PubMed1998

[An ophthalmologic image databank on the Internet].

The Internet has become a powerful, international source for information, and it has shown an exponential growth because of the ease of access and the immediate availability of information. We introduced a new ophthalmological atlas including ICD coding on the World Wide Web. So far, more than 500 lantern slides of typical and interesting ophthalmological findings have been selected and digitized. These pictures were integrated in a data base, which was arranged for ease and speed of search and retrieval. In its background, the data base contains a list of over 4700 ICD-encoded diagnoses to which the picture-documented findings are linked. Comments on pictures can be added by the author or by users. The data base contains several lists, such as a list of ICD codes and diagnoses, a list of all pictures with corresponding diagnoses, a list of all diagnoses and number of pictures, a list of those diagnoses for which the corresponding picture is available, as well as a list of comments on each picture. Special program scripts handle the user's search key words for diagnoses and extract the required information out of the data base, using Windows NT. Search results are presented on an automatically built-up webpage. To provide fast speed of search all pictures initially are shown in a small format (thumbnails) with little amount of data. The related full-size picture is retrieved by a single mouse click. Moreover, the name and institution of the author, diagnostical hints and comments on pictures by the author or by users are offered for each diagnosis available. The Giessen Ophthalmological Picture Atlas can be reached under www.med.unigiessen.de in the Internet. It allows a fast search free of charge from all over the world and, therefore, offers an additional option to obtain specific ophthalmological information for various purposes.

Databases, Factual↗

PubMed1995

[A new site-independent tonometer (ProTon) in comparison with the Goldmann applanation tonometer].

BACKGROUND: A new position-independent and portable Mackay-Marg-tonometer in miniature, the so-called ProTon (PT), was compared with reference to its clinical usefulness with the Goldmann applanation tonometer (GAT), being a commonly accepted reference. METHODS: The intraocular pressure (IOP) in 164 eyes of 85 adults (patients and volunteers without ocular disease) was measured using the sequence GAT, PT and again GAT--each three times in a row-by three different investigators in a randomized scheme. In an attempt to detect any systemic influence, the difference obtained by subtracting the value measured using PT from the value attained using GAT was compared to the central corneal thickness and radius. Moreover, the central IOP readings were compared with the peripheral IOP in 60 eyes of 30 volunteers measured by PT, to detect any possible influence of the locality of measurement. Dependence of measurement on individual influences was examined by comparing PT-values obtained by each investigator. RESULTS: Linear regression analysis between PT (y-axis) and GAT (x-axis) for an IOP range of 0 to 62 mm Hg resulted in the following equation: PT = 1.036 x GAT -2.00 with a PT value standard deviation of 1.65 mm Hg (r = 0.988; p < 0.0001). Reproducibility of each of the three PT-values (mean pair difference of 1.1 mm Hg) corresponded to the analogous first two GAT-values (differences 1.0 up to 1.2 mm Hg). The mean IOP-value of 1) the GAT measurements (1 to 3) was 18.35 mm Hg, 2) of the last three GAT measurements, 17.15 mm Hg and 3) of all PT-measurements, 16.40 mm Hg. No statistical difference was found between the IOP measured centrally and peripherally. A clinically nonsignificant dependency for PT-readings on the examiner was verified. CONCLUSION: Due to the high reproducibility, independency on examiner and acceptable correspondence of PT with GAT values, the PT appears to be a promising new development for use in measuring intraocular pressure. It will be necessary to modify the calibration of PT since IOP measured systematically about 2 mm Hg too low.

Adolescent↗