Eye pain has greatly diminished too. eye strain (so very common, esp if you work on a computer for many hours at a time). Eye pain could also be a sign of arthritis (esp rheumatoid arthritis) - do you have any other aches and pains. Have a full blood count, and ask to check your antibodies to rhuematoid arthritis and lupus.
SSI: Social Security Income: SSI: Strategic Studies Institute (US Army War College) SSI: Sensitive Security Information (US DoT)
Sum of squared errors, typically abbreviated SSE or SS e, refers to the residual sum of squares (the sum of squared residuals) of a regression; this is the sum of the squares of the deviations of the actual values from the predicted values, within the sample used for estimation.