Sample Size

The required sample size was calculated using G Power version 3.1.9.7 for a two tailed dependent paired sample t test. An effect size of Cohen d equal to 0.394 was considered clinically meaningful based on available literature. The sample size calculation was based on standard statistical principles, where Z alpha represents the standard normal deviate for the selected significance level and Z beta represents the standard normal deviate for the desired statistical power. The level of significance was fixed at 0.05 and the power of the study was set at 0.80. Based on these parameters, the minimum required sample size was estimated to be 53 subject pairs. To compensate for an anticipated dropout rate of ten percent, the final sample size was increased to 60 subject pairs, corresponding to a total of 120 eyes, with one eye per subject included in the analysis. This sample size was considered adequate to detect a moderate effect with sufficient statistical power.

Intraoperative Procedure

All enrolled subjects will undergo bilateral femtosecond laser assisted cataract surgery using either the LENSAR femtosecond laser system or the FEMTO LDV Z8 femtosecond laser system. A minimum capsulorrhexis diameter of five millimeters will be created using the femtosecond laser. A temporal clear corneal incision of two point eight millimeters and a single side port incision will be made. Phacoemulsification of the crystalline lens nucleus will be performed, followed by cortical aspiration using coaxial irrigation and aspiration. Posterior capsular polishing will be carried out. Intraocular lens implantation with either Femtis Comfort or Femtis Mplus lenses will be performed under balanced salt solution, and the lenses will be fixated to the anterior capsulotomy using a Sinskey hook. In cases where toric intraocular lenses are implanted, axis alignment will be guided using Intelliaxis technology, which provides refractive reference marks on the capsulotomy, thereby eliminating the need for manual corneal ink marking. Additional alignment assistance will be provided by the Callisto markerless system integrated into the Artevo 800 operating microscope.

Specifications of Study Lenses

Femtis Comfort is a foldable one piece aspheric extended depth of focus intraocular lens with additional capsulotomy fixation.
Femtis Mplus is a foldable one piece aspheric multifocal intraocular lens with additional capsulotomy fixation.

Both lenses are made of hydrophilic acrylic material with a hydrophobic surface coating. The optic diameter is five point seven millimeters, with an overall length of ten point five millimeters. Both lenses have zero degree haptic angulation and a refractive index of one point four six. The intraocular lens design consists of a plate haptic with additional clip haptics. The near addition is one point five diopters for Femtis Comfort and three point zero diopters for Femtis Mplus.

Clinical Endpoints

Assessment of uncorrected distance visual acuity, corrected distance visual acuity, intermediate visual acuity and near visual acuity.
Postoperative manifest refraction including sphere, cylinder and spherical equivalent.
Contrast sensitivity evaluation.

Postoperative Examinations

Postoperative assessments will be conducted on day one, day fifteen and at three months.

Uncorrected distance visual acuity using the ETDRS chart for monocular and binocular vision at all visits.
Best corrected distance visual acuity using the ETDRS chart for monocular and binocular vision at all visits.
Measurement of intraocular pressure using a non contact tonometer at all visits.
Slit lamp examination at all visits.
Manifest refraction measured in diopters on day fifteen and at three months.
Near vision assessment at thirty three centimeters using the ETDRS chart at all visits.
Intermediate vision assessment at forty, sixty and eighty centimeters using the ETDRS chart at all visits.
Dilated fundus examination on day fifteen and at three months.
Assessment of intraocular lens rotation using dilated slit lamp examination on day fifteen and at three months.
Dilated clinical photography for posterior capsular opacification assessment at three months.
Defocus curve analysis for monocular and binocular vision on day fifteen and at three months.
Contrast sensitivity testing using CSV one thousand on day fifteen and at three months.
Subjective patient satisfaction questionnaire administered on day fifteen.

Grading of Posterior Capsular Opacification

Grade one includes no or minimal posterior capsular opacification without reduction of the red reflex and absence of Elschnig pearls or pearls not reaching the intraocular lens edge.
Grade two includes mild posterior capsular opacification with reduced red reflex and presence of Elschnig pearls reaching the intraocular lens edge.
Grade three includes moderate fibrosis or Elschnig pearls within the intraocular lens edge but with a clear visual axis.
Grade four includes severe fibrosis or Elschnig pearls involving the visual axis with marked reduction of the red reflex.

Statistical Analysis

All statistical analyses will be performed using Python version three point one two and Jamovi version two point five. Normality of continuous variables will be assessed using the Kolmogorov Smirnov test, with support from the Central Limit Theorem where applicable. Continuous data will be expressed as mean and standard deviation, while categorical data will be presented as frequencies and percentages. Within group comparisons will be performed using the paired t test. Analysis of variance will be used for comparisons involving more than two groups. Non parametric tests will be applied for data that do not follow a normal distribution. A two tailed probability value of less than zero point zero five will be considered statistically significant.