This was a prospective, non-comparative, non-randomized study. We obtained an informed consent from the patients after explaining the treatment options, the risks and benefits of each procedure, and approval of the study by the ethics committee of Alexandria Faculty of Medicine. The tenets of the Declaration of Helsinki were followed and the trial was registered on clinical trials.gov (NCT04465279 on July 10, 2020).
The study included 36 eyes undergoing implanted trifocal diffractive IOL (Fine-vision, PhysIOL Liège, Belgium) at Ophthalmology department of Faculty of Medicine, Alexandria University, Alexandria, Egypt. We included patient with cataract and no other pathology. Additionally, patients’ desire for spectacle independence after surgery and with realistic expectation. Any patients with ocular comorbidity that affect the end results of the surgery such as history of ocular trauma, irregular corneal astigmatism, pupil abnormalities and capsular or zonular abnormalities that may affect postoperative centration or tilt of the lens (e.g. pseudo exfoliation syndrome and Marfan’s syndrome) were excluded. Refractive astigmatism more than 1.25 D was also excluded.
Preoperatively, all patients had a full ophthalmological examination including refractive status, Goldman applanation tonometry, slit lamp examination, fundus evaluation and biometry with LENSTAR (Haag-Streit)® by using Barrett universal II formula. All cataract surgeries used a standardized sutureless technique, capsulorhexis, hydrodissection, phacoemulsification, irrigation aspiration of cortical remnants, IOL implantation in the capsular bag and hydration of side ports. The used trifocal IOL had a foldable single-piece fully diffractive pupil dependent aspheric IOL. It is made of hydrophilic acrylic with an ultraviolet and blue light inhibitor. It has an optic diameter of 6.15 mm and an overall diameter of 10.75 mm; it has + 3.5D additional power for near vision and + 1.75 D additional power for intermediate vision, consisting of 26 diffractive steps.
Post-operative assessment
Patients were evaluated 3 months after surgery for refraction, Visual Acuity (VA); using Snellen’s chart for far, Sloan’s chart for intermediate, and Landolt ring chart for near vision. Defocus curve was used to examine monocular and binocular after corrected distant VA refractive error then inserting defocus lenses 0.50-D focus steps from (+ 1.50 to − 3.50 D) in the trial frame. We also assessed contrast sensitivity using the CSV-1000 contrast test (Green Ville-Dayton)®, high order aberration using I-trace aberrometry (Tracy Technology) and filled visual satisfaction questionnaire using patients’ satisfaction questionnaire protocol mediated by PhysIOL for each patient. High order aberration using I-trace aberrometry were additionally assessed after 1 year. Visual acuity, defocus curve and contrast sensitivity were all performed in photopic not mesopic condition.
Statistical method
Data were fed to the computer and analyzed using IBM SPSS software package version 20.0. Qualitative data were described using number and percent. Quantitative data were described using range (minimum and maximum), mean, standard deviation and median. Paired t-test was used for normally distributed quantitative variables to compare pre- and post-operative data. Significance of the obtained results was judged at the 5% level.