Evaluation of the corneal tissue consumption after a refractive lenticule extraction: nomogram reliability

Session Details

Session Title: Small Lenticule Extraction

Session Date/Time: Sunday 08/10/2017 | 11:00-12:30

Paper Time: 11:45

Venue: Room 3.6

First Author: : J.Faure FRANCE

Co Author(s): :    S. Michee   G. Houot   C. Stragliati   L. Trinh           

Abstract Details

Purpose:

To evaluate the achieved tissular ablation and postoperative residual corneal thickness after a refractive lenticule extraction. The femtosecond laser nomogram is to add 12% of the subjective refraction to get good visual results. The aim is to know if the achieved tissular ablation corresponds to the theorical tissular ablation based on subjective refraction only or to the attempted tissular ablation based on subjective refraction by adding 12%.

Setting:

Espace Nouvelle Vision refractive surgery center, PARIS.

Methods:

78 eyes undergone a refractive lenticule extraction to treat their myopia or myopic astigmatism associated or not with presbyopia. The preoperative Mean Refractive Spherical Equivalent (MRSE) was 3.9D +/- 2D. The surgical technique was performed with a femtosecond laser which creates the lenticule then surgically extracted. Corneal pachymetry was measured preoperatively and at 1 month postoperatively with the corneal OCT and Scheimpflug Imaging, to identify the achieved cap depth and calculate the achieved corneal tissular consumption. A statistical analysis was performed.

Results:

At 1 month 95% of patients raised 20/25 of Uncorrected Distance Visual Acuity (UDVA). The postoperative MRSE was -0.21D +/- 0.38. The mean achieved cap depth (=141 microns) is significantly deeper (p <0.0001) than the mean attempted cap depth (=133 microns). There is no significant difference between the achieved lenticule and the theorical lenticule (p= 0.478) which are thinner than the attempted lenticule. The theorical Residual Stromal Thickness (RST) is higher than the attempted RST (p <0.0001) and there is no difference between the attempted and achieved RST (p=0.931).The Pentacam control confirms the OCT measures.

Conclusions:

The femtosecond laser nomogram shows a good reliability in the treatment of myopia by adding 12% of the subjective refraction. The achieved lenticule thin is closer to the theorical lenticule thin and the achieved RST is closer to the attempted RST. Further studies, with higher number of patients, would be necessary to establish a nomogram based on clinical results to re-evaluate, and maybe extend, the range of myopia treated by refractive lenticule extraction fully compliant with the safety standards of postoperative corneal thickness.

Financial Disclosure:

receives consulting fees, retainer, or contract payments from a company producing, developing or supplying the product or procedure presented