Optometry is a health care profession which involves examining the eyes and applicable visual systems for defects or abnormalities as well as the medical diagnosis and management of eye disease. Traditionally, the field of optometry began with the primary focus of correcting refractive error through the use of spectacles. Modern day optometry, however, has evolved through time so that the education curriculum additionally includes intensive medical training in the diagnosis and management of ocular disease in countries where the profession is established and regulated.
The amount of energy potentially available from the difference in the salt concentrations of seawater and river water around the world is 1.4 to 2.6 terawatts, or about 20 % of local electricity consumption. This natural process does not produce carbon dioxide or any other polluting combustion emissions, nor does it result in thermal pollution.
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