Objectives:~Primary objective: To describe the tolerance of simulated astigmatism on patients implanted with Vivity at far distance.~Secondary objective: To describe the tolerance of simulated astigmatism on patients implanted with Vivity at intermediate distance.~Study Design: Prospective, single arm, descriptive, 3-month follow up.~Patient population: 30 consecutive eyes of 30 patients implanted with Vivity bilaterally with no postoperative complications. The calculation of the required sample size was based on monocular corrected distande visual acuity. A difference of 0.2 logMAR units was assumed to be clinically significant anda standard deviation of 0.05 was anticipated(data obtained from a comparative study between a bifocal and a trifocal IOL: Jonker SM, et al. Journal of Cataract Refract Surg. 2015; 41: 1631-40). Based on these assumptions, with an α of 0.05 and power of 0.8, it was calculated that 25 eyes were required in each group. Due to potential dropouts, a larger sample size has been selected.~Clinical Protocol: All patients fullfilling study criteria will be considered for inclusion three months after surgery. After patient consent, uncorrected distance visual acuity will be measured with an ETDRS chart, followed by subjective refraction (best distance correction). In all cases, mixed astigmatism will be induced with trial lens over the best distance corrected situation (considered the reference situation).~Once the best distance correction is determined, the different visual acuity evaluation procedures for this study will be performed with a Freiburg Acuity Test software package. The software will be run on a separate laptop screen calibrated to be presented at 4 meters. In this procedure, a black Landolt C is presented to the subjects and, among 8 different possibilities, they indicate the orientation of the optotype on a numeric keypad. This test minimizes the observer's bias because the presented optotype depends on the patient´s previous responses. That is, when the observer responds to a certain optotype, the software automatically modifies the size of the next optotype according to parameter estimation by a sequential test method. (7,8) Finally, all serious adverse events will be reported.~Statistical Analysis: Visual acuity values will be expressed as mean and standard deviation. Normal distribution of variables will be assessed using the Kolmogorov- Smirnov test. Pre- and post-operative data of each parameter will be compared by means of the Student's t-test. A repeated measure analysis of variance (ANOVA) will be used to gauge any statistically significant difference of the data within the different simulated situations. Differences are considered to be statistically significant for P value <0.05 (i.e., at the 5% level).
Low amounts of postoperative residual astigmatism may worsen the visual performance of patients implanted with presbyopia- correcting intraocular lenses (IOLs). Although extended depth of focus (EDoF) IOLS have introduced optical improvements, it is important to determine the tolerance of these IOLs to postoperative astigmatism. This is important for an appropriate surgical planning.~Therefore, the aim of this study is to simulate and assess the impact of mild amounts of residual mixed astigmatisms with the axis oriented in different positions (vertical, oblique and horizontal) in eyes implanted with the Vivity® IOL.