Comparative analysis of the myopic astigmatism correction by the SMILE surgery with and without cyclotorsion compensation

• Main Authors: I. A. Mushkova, S. V. Kostenev, N. P. Sobolev, G. A. Gamidov
• Format: Article
• Language: Russian
• Published: Publishing house "Ophthalmology" 2020-04-01
• Series: Офтальмохирургия
• Subjects: smile, myopic astigmatism, cyclotorsion, femtosecond laser system «visumax», astigmatism axis alignment
• Online Access: https://www.ophthalmosurgery.ru/jour/article/view/585

Purpose. To develop an alternative method of cyclotorsion compensation to improve the clinical and functional results in the correction of myopic astigmatism during the SMILE surgery.Material and methods. Two equivalent groups were formed: without (the group I) and with (the group II) cyclotorsion compensation, 30 people (30 eyes) in each group. In both groups, cyclotorsion was determined to obtain equivalent samples. Immediately before the operation, the patient cornea had been marked using the slit lamp. To obtain numerical cyclotorsion data, a corneal protractor with a scale of 1-degree accuracy was developed. The corneal protractor was applied to the eye, comparing the scale of 0 degree and the horizontal section of the microscope eyepiece. The observed deviation of the corneal mark from the horizontal section indicated the value of cyclotorsion. All patients were examined by a UDVA, CDVA, objective refraction 3 months after the SMILE surgery, Furthermore, indices of efficiency and safety were calculated. Results. The mean and standard deviations of cyclotorsion in the groups I and II were 6.16±1.31 and 7.10±1.37 degree, respectively (p<0.05). An increase of 1 or more lines of CDVA in 20% and 7%, respectively was noted 3 months postoperatively in the groups I and II. The efficacy index was higher in the group II 3 months postoperatively, with a comparable safety index. The predictability of the cylindrical component within ±0.5D relatively to the target refraction (emmetropia) in the groups I and II was 40% and 100%, respectively (p<0.05). Conclusion. The proposed method of cyclotorsion compensation allows to increase safely the predictability of laser correction for myopic astigmatism during the SMILE surgery and it is available because it doesn’t require expensive equipment. This method is recommended for a determination of cyclotorsion with a myopic astigmatism from -0.75 D and for an alignment of the astigmatism axis in a detection of cyclotorsion of more than ±5 degrees.