Biomedical subjects
Publications and source records attributed to D J Egan.
The results of a survey of the University of Missouri-St. Louis School of Optometry graduates are presented. The practice mode selected and relocation throughout the country is examined for the school's first four graduating classes. Approximately two-thirds of the graduates remained in the state with more than half in proximity of the school. Of these, one-third to one-half maintain "commercial" affiliations.
The present investigation was designed to determine the effect of lens parameters and lens environment on measurements of contact angle. The sessile drop contact angle of saline on four rigid [polymethyl methacrylate (PMMA) and silicone/acrylate] contact lens materials was examined with a Ramé-Hart goniometer to determine how front surface radius, drop size, time after drop placement, humidity, and desiccation affect measurements of lens wettability in vitro. Contact angles of Silafocon A and PMMA were relatively uninfluenced by front surface radii between 7.7 and 8.85 and 7.3 to 8.8 mm, respectively. Contact angles of Pasifocon C and modified PMMA were slightly but significantly influenced by front surface radii between 6.4 and 7.5 mm. For drop volumes from 2 to 20 microliter, all materials yielded contact angles, which were unaffected by drop size. The contact angle of lenses stored in the hydrated or dehydrated state was not affected by chamber humidity between 31 and 76%. In the ranges tested, drop size, humidity, and hydration had no significant effect on the contact angle within 1 to 6 min after drop placement. In addition, surface scratches had no effect on lens wettability. The results suggest that goniometry on contact lens surfaces, for the most part, is uninfluenced by lens parameters and environmental conditions.
Proper lens maintenance is required if contact lens wear is to be successful. Poor compliance or inadequate cleaning may lead to contact lens failures and potentially damage to the eye. With phase contrast microscopy, we addressed the effect of cleaning systems on the physical integrity of a surface-modified lens--the Silcon contact lens. Several cleaners were evaluated for their ability to clean Silcon lenses with minimal damage to the lens surface. The data demonstrated that: all cleaning techniques alter the surface appearance; scratches develop more readily on lenses received with surface irregularities; wettability does not correlate with the extent of surface scratching; recommended cleaning procedures do not directly alter the wettability of the contact lens material; and phase contrast microscopy may be a useful addition to laboratory quality control.
The introduction of high oxygen-permeable rigid lenses for daily wear has provided practitioners with an excellent alternative to other available lens materials. However, compromise in material properties may, in fact, result in lens-induced complications. This paper describes eight such "typical" problems including a treatment plan and possible alternative methods of treatment. A comprehensive summary table is provided for reference use by practitioners.
The spectral transmittances of a sample group of tinted hydrogel contact lenses were analyzed to assess the reproducibility of tinted lenses of a given density. Transmittance data were used to assess permanency of the tint after a 14-day cycle of daily cleaning, sterilization, and storage using a variety of cleaning and sterilization treatments. One-way analysis of variance of the transmittance data has demonstrated significant variations in the density of tint for Cibasoft lenses of a given color and density. However, these variations are smaller than the manufacturer's stated criterion for acceptable differences in tint density at a given tint level, i.e., light, medium, or dark. The Cibatint is stable when the lenses are cleaned with the Septicon and Miraflow systems. However, tinted hydrogel lenses from other manufacturers demonstrated changes of tint which were dependent upon the cleaning and sterilization methods used.
The effect of tinted flexible contact lenses on light sensitivity and photophobic response has often been questioned but never thoroughly investigated. An Alpascope was used to investigate whether tinted hydrogel contact lenses would relieve glare sensitivity in pre-adapted contact lens wearers. Various densities of sky blue and autumn amber Cibasoft hydrogel lenses were used in the study. Analysis of the Alpascope data using the t-test, one-way analysis of variance and Duncan's test showed that there was no reduction in glare sensitivity when tinted contact lenses were worn.
Crystalline lens thickness was measured with a Haag-Streit slitlamp biomicroscope no. 900 using a depth measuring attachment. Results indicate that relative lens thickness increases as a square function of age. Lens thickness was also measured during changes in the stimulus to accommodation. As expected, relative lens thickness increased with accommodation.
Little information is available regarding the current patterns of medication use in long-term dialysis centers. Therefore, we surveyed the medication records of 1,023 patients undergoing long-term dialysis therapy in 27 dialysis centers. The mean number of medications prescribed per patient was 7.7 +/- 0.54, increasing patient age, increasing duration of dialysis, in-center dialysis, and the presence of underlying diabetic and hypertensive nephropathy were associated with increased frequency of medication use. The use of multiple pharmacologic agents was associated with a high frequency of drug duplication (12%), potential dosage error (9%), potential significant drug interaction (15%), and use of contraindicated drugs (2.5%). A lack of individualization of the use of several pharmacologic agents was apparent. An extreme degree of center variability in drug use was also apparent. Periodic review of medication use should be undertaken in the long-term dialysis setting.
1-Alpha-acetylmethadol (LAAM) maintenance treatment has been proposed as a favorable alternative to methadone maintenance. With an unobtrusive actometer we recorded two successive 24-h cycles of spontaneous motor activity from 12 patients receiving LAAM every other day, and from five receiving methadone every day. LAAM patients were about 50% more active on days of drug administration than on no-dose days (P less than 0.001). There were no significant day-to-day differences in motility of methadone patients. LAAM administered every other day may significantly modify the human circadian rhythm of spontaneous motility; further research is thus needed before this treatment is widely adopted.
Heroin addiction may be considered an epidemic disease that is communicated by people who are addicted to the drug. It has been suggested that the most recent epidemic in the United States had its peak incidence in 1969. The age of heroin addicts entering treatment has increased systematically from 1973 to 1976 at a rate of less than one year of age per calendar year. This pattern is consistent with a moderate decline in a national heroin epidemic or a geographical migration of the epidemic from more to less populated areas. There are also seasonal trends in the age of admission to treatment.
Cocaine has attracted much attention as a recreational drug and some advocates have acclaimed it as both pleasurable and safe. This paper reviews the available evidence concerning the drug's physiological and psychological safety. Few deaths are attributed to cocaine, but its use is presently restricted by very limited supplies. Use of the drug may possibly result in liver and respiratory problems and may lead to paranoid psychotic conditions. There are many deficiencies in our knowledge of the effects of this drug.
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