Formula to measure refractive surgical accuracy proposed

Using a standardized “index of error” may give clinicians a more accurate means of evaluating the outcomes of refractive surgery, a team of physicians in Finland suggests. Inaccuracies in refractive outcomes may go unnoticed if only basic values such as corrected and uncorrected vision are used in postoperative evaluations, they suggest.

Sakari Suominen and colleagues at the University of Tampere used information given by the cross-cylinder form of surgically induced refractive change and basic methods of vector analysis to create their index of error. Using the index, surgeons would be provided “understandable” numerical values, as the index accounts for both spherical refraction and astigmatism, the researchers said.

To apply the theory in practical use, the group analyzed 20 eyes that had undergone refractive procedures with either the MEL60 or MEL70 excimer laser from Meditec.

While both postoperative best corrected visual acuity and uncorrected visual acuity were better in the MEL70 group, the difference of photorefractive keratectomy results in combined astigmatism and myopia was not statistically significant. Refractive changes achieved by the two lasers indicated the MEL60 was more accurate. This was also true when comparing the total index of error between the two groups.

The study is published in the August issue of Acta Ophthalmologica Scandinavica.