Safety in Laser Refractive Surgery


Computes de standard plot for reporting the Safety of a Laser Refractive Surgery procedure by means of lines of difference in corrected distance visual acuity between preoperative and postoperative visits


Safety in Laser Refractive Surgery


This is the most commonly used measure of safety because it answers the question, “If the refractive outcome is not totally acceptable, can the patient put glasses on again and see as well as they did before surgery?” A change of 1 Snellen line is within the range of normal biological variability for repeated measures, and therefore is not a meaningful change. A change of 2 or more Snellen lines has been generally adopted as the standard for safety.(1)

This function calculates the standardized Graph C detailed in the Journal of Refractive Surgery(2) from a two column matrix. First column should contain the preoperative visual acuity with correction (CDVA) and the second column the postoperative CDVA. The plot is only applicable to laser refractive surgery procedures.

Two additional values are returned from the function, the Safety Index (SI) known as the ratio between postoperative and preoperative CDVA(3) and the percentage of eyes with CDVA worse than 20/40 for the subgroup of eyes with CDVA of 20/20 or better preoperatively.(4)


  1. Waring 3rd GO. Standard graphs for reporting refractive surgery. J Refract Surg. 2000; 16: 757–8.
  2. Reinstein DZ, Archer TJ, Randleman JB. JRS Standard for Reporting Astigmatism Outcomes of Refractive Surgery. J Refract Surg. 2014; 30: 654–9.
  3. Koch DD, Kohnen T, Obstbaum SA, Rosen ES. Format for reporting refractive surgical data. J Cataract Refract Surg. 1998; 24: 285–7.  
  4. Eydelman MB, Drum B, Holladay J, et al. Standardized analyses of correction of astigmatism by laser systems that reshape the cornea. J Refract Surg. 2006; 22: 81–95. 

Online Course

How to obtain the Toolbox?

The Refractive Analysis is an Open Source Toolbox for Matlab developed by Rodríguez-Vallejo M for the Analysis of Vision Science Results. It is freely available for the students of our online course but you need the Matlab software to use it. Matlab software is not provided with the course.

How to enroll and follow the course?

You can enroll in the course by means of the Udemy Platform and follow the course on the same platform or through Udemy App for IOS or Android.

When the course starts and finish?

The course is asynchronous which means that it has no start or end date. The student can register whenever he wants and view the materials at his own pace.

After purchasing the course you will have lifetime access to the materials through the Udemy platform. This means that even if you complete the visualization of all the materials you will be able to access them again whenever you want to go over the content again or to the updates.

Will I have a certificate once I finish the course?

When you complete the visualization of all course materials, Udemy will provide you a certificate of course completion. You will not have to take any tests to obtain this certificate, only complete the viewing of the materials.

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