Biomedical subjects

M V Pratt

Publications and source records attributed to M V Pratt.

12 recordsLinked to original sources

PubMed1988

Intraocular lens material evaluation by iris abrasion in vitro: a scanning electron microscope study.

Prosthetic posterior chamber intraocular lenses can abrade the iris pigmented epithelium, resulting in pigment dispersion, callus formation, and iris adhesions. To evaluate iris abrasion from intraocular lens materials, we developed an in vitro test and studied three materials: polymethylmethacrylate (PMMA), silicone, and PMMA surface-modified by covalent binding of a hydrophilic polymer (surface-modified PMMA). Each lens was rubbed 1,000 times on the posterior iris of pigmented rabbits using a total force of 0.5 gram. Scanning electron micrographs of the abraded irides were scored using a subjective, nonparametric numerical scale. Polymethyl-methacrylate lenses removed iris epithelium completely, exposing underlying connective tissue. Silicone lenses damaged an area longer and narrower than the PMMA lens and also exposed connective tissue. Surface-modified PMMA lenses caused only slight surface damage, including flattening or breaking of protruding suspensory ligaments. The test conditions used cannot precisely mimic prolonged lens implantation in living subjects. Nevertheless, the results indicate that iris-lens interaction may be reduced in vivo by using a surface-modified PMMA lens. This hypothesis should be further verified by animal implantation studies.

Animals↗

PubMed1984

Clinical evaluation of the Humphrey automatic refractor.

A new automatic objective refractor was used on healthy adults. In the absence of cycloplegic drugs, spherocylindrical objective refractions performed with the instrument provided 20/20 acuity 96% as often as with standard subjective techniques. No instrument-induced accommodations effects were seen. One hundred percent of instrument spherical findings were repeatable within 0.50 diopters; all cylindrical findings were repeatable within 0.37 D. This result represents a higher level of repeatability than that reported for standard subjective refraction under clinical conditions. In the absence of cycloplegic drugs, the correlation coefficient between the instrument's findings and standard subjective spherical findings was .97 v .98 between two practitioners' subjective refractions. The average difference between cylindrical findings of the instrument and those of an experienced practitioner was 0.04 D larger than the average difference seen between two practitioners using subjective techniques.

Accommodation, Ocular↗

PubMed1984

Unusual superficial confluent form of granular corneal dystrophy.

A 53-year-old Japanese woman had corneal opacification due to granular dystrophy (GCD) since childhood. Clinically, unusual bilateral confluent dense granular opacities with a peripheral rim of clear cornea were observed. Her mother and daughter have a milder form of GCD, with circumscribed opacities separated by clear stroma. Light and electron microscopy of the patient's corneal button showed that the opacities involved the corneal epithelium as well as the stroma.

Corneal Dystrophies, Hereditary↗

PubMed1983

Unusual superficial confluent form of granular corneal dystrophy.

Chromosome Aberrations↗

PubMed1976

Human conjunctivitis. I. Diagnostic evaluation.

One hundred forty-three patients (207 eyes) with conjunctivitis or blepharoconjunctivitis were studied. Attempts were made to establish an etiologic diagnosis by clinical and laboratory methods. The etiologic diagnosis that was made on the basis of the initial clinical examination correlated poorly with the results of standard laboratory tests. Conversely, the standard laboratory evaluation failed to establish a definitive diagnosis in the majority of cases. These findings suggest that the diagnostic dogmatism prevalent in conjunctivitis is unwarranted. Morphologic signs and routine laboratory tests leave us without a verified etiologic diagnosis in a substantial number of cases.¿

Acute Disease↗

PubMed1976

Human conjunctivitis. II. Treatment.

One hundred forty-three patients (207 eyes) with conjunctivitis or blepharoconjunctivitis were investigated to determine (1) the safety of topical corticosteroid therapy and the relative efficacy of formulations of increasing potency and (2) the effectiveness of a steroid-antibiotic preparation compared to each of its components alone and to a placebo. The corticosteroids were equally effective in suppressing conjunctival inflammation; all were more effective than the placebo. Active conjunctivitis was controlled more readily by those preparations containing a steroid, both alone and in combination. The corticosteroid alone (dexamethasone) was more effective in producing inactivation of conjunctivitis than the antibiotic alone ( a mixture of neomycin sulfate and polymyxin B sulfate). This observation remained unchanged when cases of Staphylococcus aureus conjunctivitis were analyzed separately. No serious complications resulted from any treatment regimen.

Administration, Topical↗

PubMed1975

Bacteriology of normal and infected conjunctiva.

The conjunctivas of 273 inflamed eyes were cultured by both aerobic and anaerobic techniques. Isolations were obtained from 267 (97.8%) of the eyes. Aerobic organisms were isolated from 237 (86.8%) of the conjunctivas. Staphylococcus aureus from 63 (23.1%) of the diseased eyes was the aerobic pathogen most often isolated. Anaerobic bacteria were isolated from 172 (63.0%) of the conjunctivas. Propionibacterium acnes was isolated from 126 (46.2%) of the conjunctivas, and Peptostreptococcus species were isolated from 80 (29.3%) of the conjunctivas. Comparison with the bacteriology of 96 normal eyes showed that anaerobes play a much greater role as etiological agents of conjunctivitis than formerly believed. When anaerobic bacteria were isolated, they appeared on the average in 7 days, indicating that they may be missed by ordinary bacteriological culturing.

Aerobiosis↗

PubMed1974