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Biomedical subjects

S Wechsler

Publications and source records attributed to S Wechsler.

At least 19 recordsLinked to original sources
PubMed2000

[Utilization of a new night vision enhancement device (DAVIS)].

PATIENTS AND METHODS: Following complete ophthalmologic examination 37 patients with night blindness due to Retinitis Pigmentosa (sometimes Usher-Syndrome) and Choroideremia (n = 3) performed several tests with DAVIS during darkness. We evaluated the improvement of visual function on a special outside course in the city of Heidelberg (duration 1.5 to 4 hours). RESULTS: Twenty six of the patients were able to better recognize obstacles, 28 could see objects which were not seen without DAVIS. Twenty two of the 37 patients would use the DAVIS. Patients needed a visual acuity of more than 0.1 and more than 6 degree of central visual field to experience improvement with DAVIS. However, in patients with only minimal changes of the visual field, the restriction due to the presence of the device was a drawback. Sudden occurrence of light sources leads to blinding and limits the indoor use. CONCLUSION: DAVIS enhances contrast acuity especially during night and twilight. This leads to improvement of orientation due to better recognition of obstacles and allows rehabilitation of patients with night blindness for outdoor mobility. Individual test and adjustment of DAVIS is necessary to allow exact and adequate prescription.

Adolescent↗
PubMed1997

Efficacy of hand washing procedures on bacterial contamination of hydrogel contact lenses.

The effect of various hand washing regimens on transfer of bacterial contaminants from the hands to a hydrogel contact lenses was evaluated. Each of 47 subjects performed 5 different hand washing procedures, and then handled a new, sterile hydrogel contact lens. The lenses were cultured to determine colony-forming units (CFUs) and microbial identity. Median CFUs on lenses handled after washing with water, soap and water, or soap and water followed by towel drying were higher than the median CFU for lenses handled after no hand washing. The median CFU for lenses handled after soap and water washing followed by an alcohol wipe was not different from the no washing group. The majority of the contaminants were identified as Staphylococcus epidermidis. These results show that ordinary hand washing alone does not decrease, and may even increase, the amount of contaminants transferred from the hands to a hydrogel lens. Use of an alcoholic wipe after hand washing reverses this effect. Hand washing is still recommended in contact lens hygiene for removal of more pathogenic contaminants.

Colony Count, Microbial↗
PubMed1996

The high-affinity sulfonylurea receptor: distribution, glycosylation, purification, and immunoprecipitation of two forms from endocrine and neuroendocrine cell lines.

The high-affinity sulfonylurea receptor, a novel member of the ATP-binding cassette superfamily, is one component of the ATP-sensitive K+ channel. The protein is critical for regulation of insulin secretion from pancreatic beta-cells, and mutations in the receptor have been linked to familial hyperinsulinemia, a disorder characterized by unregulated insulin release despite severe hypoglycemia. The sulfonylurea receptor is present in membranes from a number of endocrine and neuroendocrine cell lines, including HIT-T15, RINm5f, alpha TC-6, AtT-20, and GH3 cells. Two forms of the receptor are present in RINm5f and alpha TC-6 cells, with apparent SDS gel molecular masses of 140 and 150 kDa. The two forms have equally high affinity, KD approximately 3 nM, for an iodinated derivative of glyburide, an anti-diabetic sulfonylurea. The receptor is a glycoprotein; treatment of RINm5f or alpha TC-6 cells with tunicamycin reduces the 140 and 150 kDa species to a single approximately 137 kDa protein. The 140 and 150 kDa receptors bind differentially to concanavalin A and wheat germ agglutinin, and lectin-affinity chromatography is ideal for the initial stages of receptor purification. After lectin-affinity chromatography, the same methods can be applied for purifying the 150 kDa form as for the 140 kDa receptor. A transiently expressed receptor with a histidine-tagged carboxy-terminus was purified by Ni-agarose chromatography, and this variant was used to demonstrate that the 140 kDa polypeptide is full length. Anti-peptide antibodies directed against the amino-terminus of the receptor and antibodies against the nucleotide binding folds immunoprecipitate both receptor forms. The results indicate the 140 and 150 kDa receptors are differentially glycosylated forms of the same polypeptide chain.

ATP-Binding Cassette Transporters↗
PubMed1994

Presbyopic drivers' vision through a convex rear view mirror.

BACKGROUND: Monovision is a commonly used modality for the presbyope who wants to wear contact lenses. If the add for near vision is in the left eye, driving an automobile creates a circumstance whereby the lens wearer cannot obtain a clear image in that eye of distant objects seen in the driver's side outside rear view mirror. METHODS: We have discovered that a stick-on convex mirror eliminates this problem by neutralizing either some or all of the power of the add. RESULTS: The driver wearing an add in the left eye can then obtain a clear image in that eye of objects behind and to the side of the automobile.

Automobile Driving↗
PubMed1984

The Urist Rorschach Mutuality of Autonomy Scale as an indicator of psychopathology.

The Urist Rorschach Mutuality of Autonomy Scale (MAS), which assesses development along a self-object differentiation and mutuality dimension, has shown considerable promise as an index of interpersonal relationship capacities. As such, MAS scores were predicted to correlate significantly with three measures of psychological pathology/health. The reliability of the scale was investigated with non-S Rorschachs and found to be satisfactory. Four-card Rorschachs from 60 previously hospitalized adults comprised the data source for the hypothesis test. Results suggest that the Mutuality Scale accurately reflects observed pathology severity at time of hospitalization and over a lifetime, but not at the time of assessment. Hence, the Urist MAS may indicate potential for pathology.

Adult↗
PubMed1981

Disinfection of hydrophilic lenses.

The cleaning and disinfection of hydrogel lenses has been discussed in the optometric literature by a number of authors. Although significant differences exist among authors regarding the disinfection method of choice, there is reasonable agreement that lenses that are carefully cleaned and rinsed are advantageous from the standpoint of both safety and lens longevity. Chemical disinfection with the soaking solution changed daily is a fail-safe method, while thermal disinfection may be less safe, perhaps due to ineffective lens case construction or thermal unit breakdown.

Bacterial Infections↗
PubMed1979

Further investigation of hydrogel lens power changes due to flexure.

Measured values for ametropia-correcting powers and front surface radii of lenses on the eye are compared to values which would be expected, using the Equal Change Hypothesis and the Invariant Normals-Constant Arc Hypothesis. Photographs of various lenses on the eye, with large molecule fluorescein instilled, are presented and show no noticeable tear lens of a finite power. These photographs and our data indicate that the Equal Change Hypothesis is not valid for predicting lens power changes due to flexure. In contrast, the Invariant Normals-Constant Arc Hypothesis appears to closely predict lens flexure effects. A clinical application of this study would be to note that thin minus hydrogels correct slightly more ametropia in their flexed state than in their unflexed state. Thin plus hydrogels correct slightly less ametropia in the flexed state than in the unflexed state.

Contact Lenses, Hydrophilic↗
PubMed1979

Effects of rigid lens flexure on vision.

Rigid lenses may flex on the eye, particularly when the center thickness is less than 0.12 mm. Rigid oxygen permeable materials are less rigid than PMMA and can be expected to flex more easily.

Adolescent↗
PubMed1978

Accuracy of manufacturers' stated center thickness of hydrogel contact lenses.

The center thicknesses of 184 hydrogel lenses--Naturvue, Hydrocurve (thin hefilcon A), Soflens, Aquaflex, and AOsoft--were measured using the Radiuscope in combination with the hydrogel lens platform. The measured center thickness of each lens was compared with the manufacturer's stated center thickness for a lens of the same parameters. In all cases, the mean difference between the measured center thickness and stated center thickness exceeded 0.01 mm, which, based on previous study, was the expected variation in the technique. The mean difference between the measured center thickness and stated center thickness of the various manufactures' lenses ranged from 0.012--0.030 mm.

Contact Lenses, Hydrophilic↗
PubMed1978

Visual acuity in hard and soft contact lens wearers: a comparison.

Visual acuity measurements with spectacles, with hard contact lenses and with hard contact lenses plus overrefraction were made on 75 eyes. Similar data was taken on 75 eyes wearing soft contact lenses. In each case, some eyes showed a decrease in visual acuity with contact lenses but the soft lenses wearers showed a greater percentage of eyes with visual acuity decrease.

Contact Lenses↗
PubMed1978

Reliability and repeatability study of a technique for measuring the center thickness of a hydrogel lens.

Various techniques of measuring the center thickness of hydrogel contact lenses are discussed. A new device called the Bisurfaced Hydrogel Lens Platform (BHLP) is described which in combination with the radiuscope allows for easy measurement of the center thickness of hydrogel lenses. The results of reliability and repeatability studies of this new device are reported which suggest the ability to measure the center thickness of hydrogel lenses within a range of .01 mm.

Contact Lenses, Hydrophilic↗
PubMed1978

Residual astigmatism in hard and soft contact lens wearers.

Residual astigmatism in a group of hard contact lens wearers and an equal size group of soft contact lens wearers was compared. Generally, the criteria used were to fit patients with refractive astigmatism greater than 0.75 D with hard lenses and those with refractive astigmatism of 0.25 D or less with soft ones. Those with refractive astigmatism between 0.25 D and 0.75 D were fitted with either modality depending upon other factors. The amount of residual astigmatism in the two groups proved to be nearly equal.

Astigmatism↗