Age-associated changes in the retinal nerve fiber layer and optic nerve head.

PURPOSE: Optical coherence tomography (OCT) measures of the retinal nerve fiber layer (RNFL) thickness and neuroretinal rim (NRR) parameters are often used as a surrogate for retinal ganglion cell content. The purpose of this study was to investigate the relationship between these morphological measures and the aging effects on these structures. METHODS: One hundred thirteen healthy individuals, aged 19 to 76 years, with no prior history of retinal of optic nerve head pathology were recruited. A circumpapillary and radial OCT scan centered on the optic nerve head (ONH) was used for data analysis. Transverse scaling was calculated for each subject using measures from optical biometry. Custom algorithms were used for morphological analysis of the ONH NRR and RNFL that included quantification of major retinal vascular contribution. RESULTS: There was a significant age-related loss of RNFL thickness (-0.23 µm/y, R(2) = 0.24, P < 0.01), major retinal vascular contribution (-0.03 µm/y, R(2) = 0.07, P = 0.01, neural rim volume (NRV, -0.004 mm(3)/y, R(2) = 0.15, P < 0.01), and minimum rim width (MRW, -1.77 µm/y, R(2) = 0.23, P < 0.01) before, and after, incorporating the Bruch's membrane opening size (sMRW, -1.86 µm/y, R(2) = 0.22, P < 0.01). When normalized, the rates of change for ONH NRR parameters (NRV, 0.69%/y and sMRW, 0.50%/y) exceeded that of RNFL thickness (0.19%/y, P < 0.01). CONCLUSIONS: Although both RNFL and ONH NRR parameters contain axons of retinal ganglion cells, there are differences in age-related changes in these measures that should be considered in clinical application.

Unrelated strain methicillin-resistant Staphylococcus aureus colonization of health care workers in a neonatal intensive care unit: findings of an outbreak investigation.

Three neonates and 5 health care workers were identified as colonized with methicillin-resistant Staphylococcus aureus (MRSA) out of 222 individuals screened during an outbreak investigation in an 18-bed neonatal intensive care unit. Two of 3 MRSA neonatal isolates demonstrated identical pulsed-field gel electrophoresis clonal patterns but no clonal association was found among isolates from the 5 employees or between employees and neonates. Increased MRSA-unrelated strain colonization among health care workers supports increased MRSA community prevalence and probable decreased utility of mass screening.