Seasonal Variation in the Presentation of Infectious Keratitis.

INTRODUCTION: Infectious keratitis is a common ophthalmic disease with the potential for severe ocular morbidity. Multiple studies have described various risk factors for the development of infectious keratitis. The purpose of this study was to analyze the seasonal variation in the presentation of infectious keratitis, and also seasonal changes in its etiologies and risk factors. METHODS: A retrospective chart review was performed on consecutive patients presenting to the emergency department at our tertiary care urban hospital center who were diagnosed with infectious keratitis from 2008 to 2013. A chi-square analysis was performed to determine whether a significant seasonal variation existed between the month, season, frequency of presentation of ulcers, and other risk factors. RESULTS: A total of 155 patients-53 men and 102 women-with a mean age of 40 (range, 3-97; median, 36) diagnosed with infectious keratitis were included in the analysis. Sixty-nine (44.5%) ulcers presented in the summer, 19 (12.3%) in the fall, 34 (21.9%) in the winter, and 33 (21.3%) in the spring (P<0.0001). Seventeen (11%) patients experienced diabetes mellitus, 60 (39%) were contact lens wearers, 12 (8%) ulcers occurred in the setting of trauma, and 19 (12%) patients underwent previous ocular surgery. A total of 92 ulcers were cultured, of which 53.8% were positive in the summer, 42.9% in the fall, 55.0% in the winter, and 42.1% in the spring. A significant seasonal variation in the frequency of 1 organism, Pseudomonas aeruginosa, was identified (P=<0.0001); up to 47.6% of culture-positive ulcers in the summer were P. aeruginosa positive, whereas cultures in the remaining seasons were 0, 9.1% and 12.5% positive for this organism. DISCUSSION: The summer months have a higher frequency of infectious keratitis and P. aeruginosa positivity in this study. Possible factors leading to this increased summer presentation include warmer temperatures, higher humidity, and greater ocular exposure to water. Clinicians should increase their vigilance and education to high-risk patients during these periods and potentially modify empiric treatment regimens.

Differential Effects of C1qa Ablation on Glaucomatous Damage in Two Sexes in DBA/2NNia Mice.

PURPOSE: To determine the sex and age-related effects of C1qa ablation on retinal ganglion cell (RGC) and optic nerve (ON) axonal loss in a mouse model of glaucomatous neurodegeneration. METHODS: Congenic C1qa mice were generated in the DBA/2NNia background. Female and male knockout (-/-), heterozygous (+/-), and wild type (+/+) mice were aged up to 14 months and IOPs were recorded in a subset of animals. Retinas of mice from all three groups at 5-6, 9-10 and 11-13 months of age were flat-mounted after retrograde labeling with Fluorogold. Imaged retinas were scored (RGC score) semi-quantitatively on a 10 point scale by two independent observers. A subset of retinas and optic nerves were also used for measurement of total number of RGCs. Semi-thin sections of ON were imaged and graded (ON score) for the amount of axonal damage semi-quantitatively, by two masked observers. Analysis of covariance (ANCOVA) was used for statistical comparisons. Microglial cells in flat-mounted retinas of 5-6 month old C1qa -/- and C1qa +/+ mice were used for assessment of microglial activation utilizing morphological criteria. RESULTS: Female C1qa -/- mice had significantly higher IOP (p<0.000001, ANOVA) between 8 and 13 months of age compared to C1qa +/+ animals. No differences in IOPs between animals of the three genotypes were observed in males. At 5-6 months of age, there was no difference in RGC or ON scores between the three genotypes in animals of either sex. At 9-10 months of age, female mice didn't show significant differences in RGC or ON scores between the three genotypes. However, male C1qa -/- and C1qa +/- mice of the same age had better RGC and ON scores (p<0.003 and p<0.05, ANCOVA, for RGC and ON scores, respectively) compared with C1qa +/+ mice. At 11-13 months of age, female C1qa -/- mice had better RGC scores (p<0.006, ANCOVA) compared to C1qa +/+ and C1qa +/- animals. Accordingly, C1qa -/- mice had higher RGC counts (p<0.03, t-test) compared to C1qa +/+ animals. In male mice, there was a tendency for 12 month old C1qa -/- animals to have better RGC scores and higher RGC counts, but this didn't reach statistical significance. ON scores in 11-13 month old animals of either sex were not different between all three genotype. Microglial activation in male 5-6 month old C1qa -/- mice was decreased compared to C1qa +/+ animals; no such effect was seen in females. CONCLUSIONS: Absence of C1qa ameliorates RGC and ON loss in the DBA/2NNia strain, but this effect differs between the two sexes. C1q-mediated RGC damage seems to be more potent than IOP-mediated RGC loss. In contrast, C1qa absence provides axonal protection early on, but this protection cannot overcome the effects of significant IOP elevation.