Diffusion of volatile organics through contact lenses.

The purpose of this study was to determine the effect of contact lenses on the exposure of eyes to vapors of organic solvents. Vials of normal saline with and without contact lens barriers were exposed to known concentrations of vapors of acetone, diethyl ether, trichloroethylene (TCE), and toluene. Uptake in vials with hydrogel polymacon (38% water content) lens interfaces was consistently lower than in control vials for exposure times of 2 minutes to 4 hours. Average concentrations were 54%, 26%, 28%, and 25% of the control for acetone, ethyl ether, TCE, and toluene, respectively. After removal from the test chambers, vials with polymacon lenses in place retained ethyl ether, TCE, and toluene significantly longer than control vials without lenses, and concentrations were generally equal in experimental and control vials 24 hours after removal. Uptake across rigid gas permeable lenses (RGP) (silicone/acrylate and fluoropolymer) and hydrogel lenses (polymacon, vifilcon A and etafilcon A) was positively correlated with the water content of the lenses. Uptake across hydrogel lenses ranged from approximately 10 to over 100 times the uptake across RGP lenses for all test compounds except acetone after exposure times of 4 minutes and 30 minutes. Based on these data, we conclude that contact lenses worn in environments containing volatile organic solvents may decrease the exposure of the eye to these compounds.

Experimental bacterial endophthalmitis following extracapsular lens extraction.

The rapid increase in popularity of extracapsular cataract extraction may predispose the eye to postoperative bacterial infections by introducing viable organisms through the additional instrumentation and irrigation necessary for the extracapsular technique. Lens protein released into the aqueous humor of the anterior and posterior chambers may enhance or inhibit the ability of organisms to grow in the aqueous humor. In the intact eye the lens acts as a significant protective barrier restricting the posterior extension of the infectious processes. This study was undertaken to determine if extracapsular lens extraction enhances the ability of common bacteria to infect the anterior segment of the eye and if the posterior lens capsule acts as a protective barrier denying the infectious process access to the vitreous body. Approximately 1000 colony forming units (CFU) of Staphylococcus aureus were required to produce bacterial endophthalmitis in less than one-half of normal rabbit eyes and eyes following extracapsular lens extraction. Discission of the posterior lens capsule tripled the number of eyes infected. As few as fourteen CFU could produce infections in some eyes if the posterior capsule was incised. Extracapsular lens extraction does not predispose the eye to bacterial endophthalmitis if the posterior lens capsule remains intact. Interruption of the posterior lens capsule does allow a small number of organisms to establish an intraocular infective process. Lens protein and other constituents released into the aqueous humour appear to have little effect on the growth of the test organisms.

Some unusual periorbital dermatoses.

Three case reports of primary periorbital dermatitis are presented. The etiology of these were molluscum contagiosum, Microsporum canis, and Coccidioides immitis. In each case, the presenting complaint was unusual since the primary lesion started in the periorbital region.

Trabeculotomy with continuous argon laser.

This study substantiates the theory that effective long-term laser treatment for glaucoma is possible in those patients with chronic non-obstructive phakic glaucoma. A common mechanism of glaucoma in these cases would appear to be some type of trabecular collapse. Correction of this trabecular defect may be accomplished with multiple small low-intensity argon laser burns symmetrically placed in the entire circumference of the meshwork. Conversely our histological data indicate that high-intensity burns result in the development of heavy fibrous tissue proliferating within the trabecular meshwork and Schlemm's canal which would appear to contribute to further filtration resistance.

Monocular diplopia.

Monocular diplopia may be of external, optical, neurological, neuromuscular, or psychogenic origin. It may develop spontaneously or it may be induced by surgery or trauma. Because treatment is usually directed toward the cause, determination of the etiology is important. Useful diagnostic techniques are described, as are treatment modalities for monocular diplopia of various origins.

Glaucoma and expulsive hemorrhage mechanisms in the Sturge-Weber syndrome.

An eye from an adult with Sturge-Weber syndrome and glaucoma is described histologically following enucleation for massive choroidal hemorrhage. The specimen is noted to contain hemangiomas of the episclera and choroid as well as a partial angle cleavage abnormality. Histologic evidence reviewed herein supports the concept that infantile glaucoma associated with this syndrome may be associated with marked filtration angle cleavage deformities. Some Sturge-Weber patients who develop unilateral glaucoma later as juveniles or adults appear to have milder expressions of angle cleavage abnormality or a forme fruste of this angle disorder. Any surgical procedure for this glaucoma preferably should be one which minimizes or eliminates operative hypotony, thus avoiding a possible expulsive hemorrhage.

Primary care of ocular emergencies. 1. Traumatic injuries.

The primary care physician often must shoulder the heavy medical (and often legal) responsibility for diagnosis of ocular emergencies and for definitive or interim therapy. Proper and timely simple diagnostic procedures followed by appropriate therapy may mean the difference between permanent loss of sight or recovery of useful vision. Lacerations, contusions, and foreign-body injuries are discussed here.

Primary care of ocular emergencies. 2. Thermal, chemical, and nontraumatic eye injuries.

First- and second-degree flash burns can be treated by the primary care physician, but third-degree burns will require a specialist for extensive debridement and skin grafting. Actinic keratitis, often associated with welding and snow skiing, is painful but can be treated with drugs in the office. There is no treatment for eclipse burn. Alkali is more toxic to the eye than is acid and can dill corneal epithelium and endothelium. All chemical burns require copious irrigation, but a patient with an alkali burn must be sent immediately thereafter to an ophthalmic surgeion. Acute glaucoma and acute occlusion of the central retinal artery are the two major nontraumatic eye emergencies. Patients with either of these injuries should be referred to a specialist after emergency measures have been taken.

Gentamicin in ophthalmology.

Gentamicin, widely used in the treatment of ocular infections, is discussed in terms of its chemical structure, effectiveness against various organisms, and pharmacology. Dosages and methods of administration are detailed and toxic effects, reversible and irreversible, are noted.