Microsporidia and Acanthamoeba: the role of emerging corneal pathogens.

Parasitic organisms are increasingly recognized as human corneal pathogens. A notable increase in both well-defined Acanthamoeba keratitis and a more dramatic increase in reported cases of Microsporidia keratitis have suggested significant outbreaks of parasitic keratitis around the world. Historical and contemporary baselines as well as a familiar associated clinical presentation reinforce the significant outbreak of Acanthamoeba keratitis in the United States. The remarkable rise in cases of Microsporidia keratitis, however, lacks these established baselines and, further, describes a disease that is inconsistent with previous definitions of disease. While a well-defined, abrupt increase strongly suggests temporally related risk factors, most likely environmental, involved in the Acanthamoeba outbreak, the rise in Microsporidia keratitis suggests that increased awareness and improved diagnostic acumen are a significant factor in case ascertainment. Regardless, recent evidence indicates that both parasitic diseases are likely underreported in various forms of infectious keratitis, which may have unrecognized but significant implications in the pathogenesis of both primary protozoal and polymicrobial keratitis. Further understanding of the incidence and interaction of these organisms with current therapeutic regimens and more commonly recognized pathogens should significantly improve diagnosis and alter clinical outcomes.

Estimating the total exposure to air pollutants for different population age groups in Hong Kong.

Given that Hong Kong is one of the most densely populated cities in the world, the exposure of the Hong Kong people is one of the interesting research areas. In this study, an indirect approach was used to estimate the exposure to nitrogen dioxide (NO2), respiratory dust (PM10) and carbon monoxide (CO) pollutants experienced by different age groups of people in Hong Kong. The average concentrations of the 20 major microenvironments obtained from our measurement survey data, together with the people activity pattern data obtained from 7-day recall questionnaires, were used to predict frequency distributions to exposure assessment. Our results showed that Hong Kong people spent more than 86% of their time indoors. Homes were shown to be the one of the major exposure sites to NO2, CO and PM10 for all age groups. Our results also indicate that the 24-h NO2 exposure for individuals, irrespective of age, spending more than 2 h in commuting daily, was observed to be exceeding the 24-h NO2 exposure standards. This study was one of the pioneering studies with valuable contribution for modeling the estimates of exposures to NO2, PM10 and CO of different age groups in Hong Kong.

Corneal first surface optical aberrations and visual performance.

PURPOSE: Wavefront analysis has demonstrated that refractive surgery-induced corneal first surface aberrations are large, are dominated by symmetric aberrations (spherical-like aberrations), and are correlated to measures of visual performance. It is not clear whether the correlation between corneal first surface aberrations and visual performance can be generalized to other corneal conditions where large asymmetric aberrations (coma-like aberrations) may dominate the aberration structure. The purpose of the research reported here was to determine the general utility of corneal first surface wavefront analysis in predicting visual performance. METHODS: Patients were 13 normals and 78 patients with a variety of corneal conditions including surgically removed pterygia, penetrating keratoplasty, keratoconus, radial keratotomy, laser in situ keratomileusis, and others. Videokeratographs were taken for all patients and used to calculate corneal first surface wavefront variance for 3 and 7 mm pupils. Similarly, visual performance was quantified by measurements of contrast sensitivity and high and low contrast acuities through both 3 and 7 mm pupils. RESULTS: Statistically significant correlations existed between all three measures of visual performance and the corneal wavefront variance. All relationships were stronger for the 7 mm diameter-pupil condition than the 3 mm pupil. CONCLUSION: Regardless of the cause, corneas with increased wavefront variance showed a quantifiable decrease in visual performance that was pupil size dependent.

Therapy of nonnecrotizing anterior scleritis with subconjunctival corticosteroid injection.

OBJECTIVE: To determine the safety and efficacy of subconjunctival triamcinolone (Kenalog) in treating nonnecrotizing anterior scleritis. DESIGN: The authors conducted a retrospective review of all patients treated with depot subconjunctival corticosteroid injection for scleritis from January 1988 to May 1993. Response to therapy was determined by subjective improvement in pain and a decrease in clinical signs of ocular inflammation. All patients received subconjunctival injections of triamcinolone by the same technique, and the minimum observation period for complications was 6 weeks. RESULTS: Eighteen patients (90%) had relief of their symptoms with clinically observable improvement in inflammation, whereas two patients (10%) responded poorly. Nine patients (45%) required no further therapy. Average symptom-free interval was 18 weeks in patients with recurrent scleritis. No complications of scleral thinning, perforation, or glaucoma occurred in any patients. CONCLUSION: Subconjunctival triamcinolone injection is highly efficacious in treating nonnecrotizing anterior scleritis without unreasonable risk of thinning and/or perforation and should be considered as adjunctive therapy in localized disease.