A photothrombotic model of small early ischemic infarcts in the rat brain with histologic and MRI correlation.

Over the last two decades several studies have suggested the role of photothrombotic occlusion of cerebral microvessels using rose bengal, resulting in small strokes in rodents that resemble those in humans. This paper describes such a photothrombotic method of acute small stroke induction in rats with histopathologic and in vivo magnetic resonance imaging (MRI) observations from 3 to 6 h after irradiation, which is homologous to a human autopsy specimen. Utilizing 30 min of irradiation with minimal beam intensity (0.1 W/cm(2)) cold white light in conjunction with 20 mg of intravenous (iv) rose bengal as a rapid infusion, small infarcts were induced photochemically in the frontal lobes of six rats. The infarcts showed a consistent pattern on histologic and in vivo MR sections when examined within 7 h or less of irradiation. Both MRI and histologic sections were comprised of (a) a superior zone of infarcted neurons, (b) a middle curvilinear transition zone of edema on MRI and histologically vacuolated neuropil, and (c) an inferior zone of normal neurons. Shorter duration water-sensitive (T2)- and postgadolinium longer duration (T1)-weighted signal decay images both showed a curvilinear hyperintense transition zone of edema. The mean infarct and transition zone areas measured from the histologic sections were comparable to those measured on the MRI. The infarct model described above allows in vivo observations using MRI with the potential for use in testing putative neuroprotective agents. As demonstrated by a comparison with the histologic features of such infarcts in surgical and autopsy brain specimens, the model is relevant to acute human ischemic infarcts.

Distribution of lead and transthyretin in human eyes.

BACKGROUND: The retinal pigment epithelium serves as a defensive barrier to the retina in the same way that the choroid plexus functions in the brain. Previous studies have shown that lead sequestration in the choroid plexus reduces the production and secretion of transthyretin by the choroid plexus. The purpose of this study was to investigate the distribution of lead and transthyretin in human eyes and to explore the potential effect of lead on transthyretin in human eyes. METHODS: Eight pairs of human eyes were obtained from the New York City Eyebank within 24 hours of postmortem. The eyes were dissected to obtain the aqueous, vitreous, retina, and choroid. Lead and transthyretin concentrations in ocular tissues and liquids were determined by atomic absorption spectrophotometry for lead and radioimmunoassay for transthyretin. Lead accumulated in the retina at concentrations that were 166, 739, and 5 times higher than those in the aqueous, vitreous, and choroid, respectively (p < 0.05 for all comparisons). Lead concentrations in ocular tissues or intraocular liquids did not change as a function of age or gender. The concentration of transthyretin in the vitreous (14.4 +/- 5.1 SE microg/mL) was twice as much as in the aqueous (7.0 +/- 1.1SE microg/mL) and was significantly correlated to that in the retina (r = 0.93, p < 0.005). CONCLUSIONS: This study indicates that lead accumulates in human ocular tissues, particularly in the retina. The markedly elevated retina lead level and its relationship to ocular transthyretin and other macromolecules bear further investigation.

The prevalence of eye disease in nursing home and non-nursing home geriatric populations.

The objective of this study was to determine whether rates of eye disease among the elderly are higher for residents of nursing homes than for persons who reside elsewhere. Articles reporting the prevalence of eye disease in geriatric populations (classified as nursing home or non-nursing home) were identified through a Medline search and a search of articles' bibliographies. Identified articles were reviewed, and the relevant data compared with prevalence rates obtained from 738 residents of two nursing homes in New York City. Each of the nursing home residents received an ocular examination upon admission that determined the presence or absence of four varieties of eye disease-i.e. cataracts, age-related macular degeneration, glaucoma, and diabetic retinopathy. Demographic data were obtained through chart review. Results indicate that prevalence rates of eye disease found in geriatric nursing home populations are generally higher than those found in other geriatric populations. With the exception of the rates for diabetic retinopathy, the rates found in the combined nursing home population sampled in this study were much higher than those reported in any previous study. It is concluded that eye disease is a more serious problem for elderly residents of nursing homes than for the elderly who reside in the community. Possible reasons for this are discussed.

Acute red eye. Differentiating viral conjunctivitis from other, less common causes.

Adenoviral conjuctivitis is one of the most common causes of acute red eye. Other diagnostic considerations include herpes virus conjunctivitis, chlamydial conjunctivitis, allergic conjunctivitis, and various other less common infections. Careful history taking can help in identifying a viral cause. The presentation may range from a minor conjunctivitis resulting from an upper respiratory tract infection to a serious, debilitating epidemic keratoconjunctivitis. Local care and interventions to minimize transmission are the cornerstones of management. Infection is usually self-limiting. Warm soaks and artificial tear lubricants may relieve itching and burning. Patients should be instructed to avoid touching their eyes, wash hands often, use disposable towels, and avoid group activities for as long as an ocular discharge is present. Use of topical corticosteroids or antibacterial preparations can lead to complications, and injudicious use of topical corticosteroids may mask serious conditions that require other interventions.

Iridoschisis: high frequency ultrasound imaging. Evidence for a genetic defect?

AIMS: To elucidate changes in the anatomy of the anterior chamber associated with iridoschisis, a rare form of iris atrophy, and their potential contribution to angle closure glaucoma. METHODS: Both eyes of a 71-year-old woman with bilateral iridoschisis and fibrous dysplasia and her asymptomatic 50-year-old daughter were scanned with a very high frequency (50 MHz) ultrasound system. RESULTS: The symptomatic patient exhibited diffuse changes in the iris stoma with an intact posterior iris pigmented layer in both eyes. These changes were clinically compatible with the lack of iris transillumination defects. Additionally, iris bowing with a resultant narrowing of the angle occurred. The asymptomatic daughter showed discrete, but less severe iris stromal changes. CONCLUSION: This is the first detailed study of high frequency ultrasonic imaging of the iris in iridoschisis. The observed structural changes suggest angle narrowing by forward bowing of the anterior iris stroma may be a mechanism of IOP elevation in this condition. The ultrasonic detection of iris changes in the asymptomatic daughter of the symptomatic patient and the association of iridoschisis with fibrous dysplasia suggest a possible genetic component in the pathogenesis of this condition.

Vitamins for cataracts and macular degeneration.

1. In some instances, the lay and scientific community already have concluded that antioxidants confer protection against cataracts and macular degeneration, and have been using them toward that end for some years. 2. Because vitamins are not considered drugs, their prescription and dosage are not subject to the regulation of the Food and Drug Administration. While some studies support their use, others do not. 3. Until sound randomized, controlled clinical trials have been completed in the use of antioxidant supplements and the development of cataracts and macular degeneration, the exact therapeutic role and dosage of antioxidants will remain less than clear. As is the case with any drug, short- and long-term side effects, as well as potential toxicity, have to be carefully weighed against the protective benefits in each individual case.

Computers and eyestrain.

Computer video display terminals have revolutionized the home and office work habits of millions of people. Although no verifiable organic ocular diseases have been shown to derive from computer monitors, symptoms related to eyestrain are very common. Some 10% to 15% of patients presenting for routine eye exams complain of computer-related headache and eyestrain. Comprehensive ocular examination including distance, intermediate and near refraction, as well as uncovering evidence of ergonomic and lighting inadequacy, often is clinically quite helpful. A careful eye exam with particular attention to middle and near range refraction, oculomotor balance, the workstation, lighting, and seating comfort will assist measurably in alleviating eyestrain.

Extended-wear aphakic soft contact lenses and corneal ulcers.

A review of 100 aphakic extended-wear soft contact lenses is presented for the period July 1980 to August 1981. Four previously successfully fitted patients with either American Optical Company's Sofcon or Cooper Laboratories' Permalens for extended wear developed corneal ulcers either directly under the lenses or shortly after removal. Three of the female patients were well controlled diabetics without retinopathy, one of whom sustained severe visual loss and neovascular glaucoma after a pseudomonas ulcer. Another patient, who had developed a Seratia marcescens ulcer 3 months later, developed metastatic carcinoma of the bowel. Special attention to diabetic aphakic patients being fitted with extended-wear soft contact lenses is suggested.