Slope and intercept parameters for linear functions to determine the age-expected average of normal sensitivities across the test locations in a given sector of the HFA 24-2 perimetric field, which corresponds to a sector of the RNFL thickness scan, as presented in Fig. 6. The modified sector-MD is the average measured SAP sensitivity for a sector minus the expected average SAP sensitivity derived from the linear function with slope and intercept parameters listed in the table. The sector-MD is used in equation 12 to derive a stage-dependent correction, c.