The change on the spherical equivalent with time
Updated on version: 1.0.0


In laser refractive surgery procedures it is important to control the stability of the postoperative refraction with time. For this purpose, the standard proposes a stability graph that shows the variation of the postoperative spherical equivalent at different follow-up visits through the mean and standard deviation of the sample.


The change on the spherical equivalent with time


This function calculates the standardized Graph E detailed in the Journal of Refractive Surgery(1) from a multiple column matrix. Columns should contain:

  • The preoperative spherical equivalent in the first column.
  • As many columns more as follow-up visits have been conducted. The standard suggests 2 weeks, 1 month, 3 months, 6 months and 12 months but the function can report the number of months specifically measured in your project.


  1. Reinstein DZ, Archer TJ, Randleman JB. JRS Standard for Reporting Astigmatism Outcomes of Refractive Surgery. J Refract Surg. 2014; 30: 654–9.

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