Calvin Hanna

Cataracts Associated with Allopurinol Therapy

The National Registry of Drug-Induced Ocular Side Effects has accumulated 30 cases of suspected allopurinol-induced lens changes. The cataracts associated with this antihyperuricemic agent are initially anterior and posterior lens capsule changes with anterior subcapsular vacuoles. With time, wedge-shaped anterior and posterior cortical haze occurs, along with dense posterior subcapsular cataracts. Histologic studies of these cataracts showed no unique or identifying features. These cases do not prove a cause-and-effect relationship, but raise the suspicion that allopurinol may be cataractogenic in some patients. Additional case reports and lens material should be sent to the National Registry of Drug-Induced Ocular Side Effects, Oregon Health Sciences University, 3181 S.W. Sam Jackson Park Rd., Portland, OR 97201.

Lens epithelial cell proliferation and migration in radiation cataracts.

The left eyes of young and adult mice and rats were exposed to 2400 r of gamma radiation from a Co/sup 60/ source administered at the rate of 40 r/min. The right eyes of the animals served as controls. Thymidine--tritium is incorporated into the deoxyribonucleic acid (DNA) in the synthesis phase of cell division. The number of epithelial cells labeled per section of lens and the number of grains found per cell were taken as a measure of nucleic acid synthesis. The change in position of labeled cells with time was taken as an indication of cell movement. Initially, the grain count per cell decreased temporarily and then remained near the control level after irradiation. Frequency of cell labeling remained constant for several weeks and then increased moderately. The germinative zone remained in the normal pre-equatorial position even though there was considerable cell damage evident in the epithelium and cortex regions of the lens. Cells from the germinative zone in the adult rat moved slowly after irradiation. These labeled cells were not found to enter the lens cortex until after the cataract was well advanced or complete. In younger animals cell migration was fast enough so that labeled cells movedmorexa0» into the lens and migrated toward the posterior pole sometimes before the cataract was complete. In the mouse these labeled cells migrated toward the posterior pole just under the lens capsule to form plaques. Lens fiber damage in all cases was well advanced before cells in the zone of DNA synthesis at the time of irradiation migrated and reached the area of opacity in the lens cortex. Previous work on radiation cataract formation has been critically reviewed, and a postulated sequence of events leading to the cataract has been put forth. In this sequence of events, damage to the newly forming lens fibers at the time of irradiation is seen as directly leading to the cataract. (auth)«xa0less

Use of dilute drug solutions for routine cycloplegia and mydriasis.

Clinic patients and students were given several regular drops of commercial 10% phenylephrine HCl, and 1.0% cyclopentolate HCl or 1.0% tropicamide HCl. The drops were given three times at five-minute intervals. Mydriasis and cycloplegia were determined and compared with the results obtained by using one of the following: microdrops (0.005 or 0.01 ml) of a mixture of 5% phenylephrine HCl and 0.5% tropicamide HCl, or regular drops of mixtures of 1% phenylephrine HCl, or 0.4% hydroxyamphetamine hydrobromide with 0.1% cyclopentolate HCl, or 0.1% tropicamide in a vehicle of 1.6% or 1.0% methylcellulose 400, or artificial tears or lubricants (Absorbobase, Contique, Isopto Tears, Liquifilm, Lyteers, Ultra Tears). Except for an initial lag in the production of mydriasis with the diluted mixtures, the results were similar for all preparations. The diluted solutions produced little ocular irritation or tearing.

Delivery of antibiotics to the eye

Abstract The drug delivery systems which are currently available in general use are ineffective in the production of bacteriostatic concentrations of antibiotics in the aqueous humor of man for a period of days. An analysis of the parental, subconjunctival, and topical routes of administration of the antibiotics to the eye is made. Examples of recent studies are given to indicate approaches that can be made for the more effective use of antibiotics in the eye. These examples include the use of an initial large dose for parental administration, studies on the mechanism of penetration of drug into the eye after subconjunctival injection and the use of antibiotics suspended in ointment for topical use.

Allergic Dermatoconjunctivitis Caused By Phenylephrine

Severe bulbar and palpebral conjunctivitis and periorbital dermatitis developed in two of our patients who used phenylephrine hydrochloride eyedrops. The allergic agent was identified as phenylephrine. To the best of our knowledge, a positive patch test to pure 10% phenylephrine in water by Mathias and associates 1 is the only report of allergy to this drug by itself. However, there are several reports of ocular reactions to commercial phenylephrine eyedrops that contain other chemicals, including benzalkonium and mercurials.

Mydriasis from Topically Administered Phenylephrine HCl Powder

Microgram amounts of finely powdered phenylephrine HCl were administered to the conjunctiva of volunteers. A dose-response curve for white subjects showed a threshold mydriasis of less than 5 micrograms and a clinically useful mydriasis was obtained with one application of 50 micrograms. The time-response curve for the one time use of 50 micrograms of the powder was equivalent to giving three applications of 10% phenylephrine HCl drops. Twenty-five micrograms of pilocarpine HCl powder produced marked miosis. We investigated methods to deliver nonirritating microgram amounts of powdered phenylephrine HCl, pilocarpine HCl, and fluorescein.

A Common Ocular Pathology Spheroidal Degeneration Of the Cornea and Conjunctiva

The most common corneal pathology is the development of small, white to golden spheroids located in the stroma and composed of protein, RNA, and collagen (1). These bodies can appear spontaneously in the cornea and conjunctiva of the aged or around the site of corneal and conjunctival trauma (2). The spheroids of the aged have different corneal patterns, depending on the person’s geographic location or insulting agent (3). Until an etiologic or chemical structure is known, we prefer the descriptive term of spheroid degeneration of the cornea and conjunctiva.