Three different types of contrast sensitivity chart were used on normal patients by six optometrists in clinical practice. The charts were the Vistech, the Pelli-Robson and the Cambridge low-contrast gratings test. We examine the data in terms of the differences between optometrists and the variation of contrast sensitivity with the age of the patient. There was a highly significant difference between the scores from different optometrists for all three charts. We attribute this to variability in measurement technique. There was also a highly significant effect of age for all three charts, with older observers tending to exhibit lower contrast sensitivity. On the Vistech chart, this sensitivity deficit was most pronounced at higher spatial frequencies. The level of redundant information in the tests is discussed.
BECP's cumulative FFC savings of emissions of the greenhouse gases of carbon dioxide (CO2), nitrous oxide (N2O), and methane (CH4) in CO2-equivalents in Table ES.2 are almost3.9 billion metric tons. That is equivalent to three-quarters of all energy-related emissions of the United States in 2012. These benefits do not count the reduction of other energy-related air pollutants shown in Table ES.2, or billions of dollars in saved future investment in facilities to supply the natural gas, electricity, and fuel oil to the residential and commercial sectors that would no longer be required. v This analysis also estimated the potential energy savings for 2013-2040 for residential and commercial code activities under ideal adoption and compliance conditions. The estimate represents the energy, cost, and emissions that could be saved on new post-2013 construction, as well as existing stock, with immediate code adoption and 100% compliance. Full cumulative site energy savings potential for 2013-2040 equals 42.6 quads, with residential and commercial energy code activities contributing approximately 50% each. Primary energy savings potential is 77 quads, which translates to FFC energy savings of nearly 80 quads. Cumulative energy cost savings potential equals approximately $330 billion (2012$). Annual CO2 savings potential reaches 461 million metric tons at the end of 2040, and the cumulative potential carbon savings by 2040 are estimated at over 6.2 billion metric tons of CO2. For more details of the energy savings potential, as well as potential cost and emissions reductions, refer to Appendix A.
Purpose• To develop an instrument for the comprehensive measurement of the impact of refractive correction on quality of life in the pre-presbyopic age group.• To design the questionnaire to be relevant to refractive correction by spectacles, contact lenses and refractive surgery such that it is suitable for comparison between correction mode and for studies of treatment outcome.
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