Fig. 1 Top view imaging with Galilei G4
a: Four dots hair cross (first Purkinje reflex). b: Pupil center (small white cross), angle kappa and chord mu data (Galilei G4 software).
Aberrometry assessment was performed with VX120 (Visionix, Inc.); this is a multimodal platform, combining Scheimpflug and Placido-disc technology, together with an Hartmann-Shack aberrometer which directly measures corneal and total ocular aberrations, inferring the internal aberrations from the aforementioned data. All measurements were performed under the same illumination conditions (mesopic pupil at 5.5 lux).
Regarding distance measurement between protocol landmarks and reference points, the authors have chosen a hybrid measuring method. For IOL positioning assessment, eye photographs were obtained with Galilei G4 at the protocol timepoint (36 months postoperatively) and subsequently processed with the Fiji’s Image J program (software version 2.0.0-rc-49/1.51a), which allowed several measurements of the distance between FPR, PC, OC and IOL center. Regarding IOL centration, the postoperative first Purkinje reflex was defined as the reference point, as it closely relates to the visual axis. Henceforth, decentration was determined according to the measured distances between FPR and the IOL centre (inner diffractive circle). Calibration was accomplished by using the constant limbus horizontal size as a reference, allowing pixel measurements conversion into millimetres for each eye.
Biometry was performed using optical interferometer Galilei G6 (Ziemer Ophthalmic systems AG) and every subsidiary examination (such as OCT, corneal topography, specular microscopy, etc.) was conducted by a technician, unaware of the type of capsulotomy centration. Participants’ manifest refractions were collected (sphere, cylinder, and spherical equivalent), with objective refractive errors assessed by an autorefractor (Topcon Co. Ltd.).
Posterior capsule opacification was assessed at the 3 years postoperative visit, after pupil dilation, with a modified version of the Evaluation of Posterior Capsule Opacification (EPCO), as described by some authors. For that matter, retroillumination images were obtained with Visionix and subsequently processed with Image J, which allowed identification, marking and calculation of density areas by performing pixel counts. The density of the opacification behind the IOL was clinically graded as follows: 0 = none; 1 = minimal; 2 = mild; 3=moderate; 4=severe. Then, individual PCO score for each eye was determined with Evaluation of Posterior Capsule Opacification (EPCO) by multiplying the density of the opacification (graded from 0 to 4) by the fractional PCO area involved behind the IOL optic.
Patient reported outcomes were assessed using a 5-point Likert scale questionnaire regarding the level of satisfaction (graded from 1 – very dissatisfied; 2 – dissatisfied; 3 - neither satisfied nor dissatisfied; 4 - satisfied; 5 - very satisfied), whereas quality of vision was determined by a 4-point Likert scale questionnaire comprising the existence of visual disturbance or photic phenomena, graded from 0 (none) to 4 (very high).
Lens transparency was assessed by slitlamp examination and assigned a grade according to the Lens Opacities Classification System (LOCS) III. Corneal topography and tomography were determined using a Placido - dual Scheimpflug device (Galilei G6). Macular spectral-domain optical coherence tomography was performed with a modular ophthalmic imaging platform (Carl Zeiss).
Postoperatively, all patients were evaluated at 1 day, 1 week, and at 1, 6, 12, 24 and every year thereafter and 36 months. Visual acuities were assessed with Snellen chart (for distance) and reading Jaeger chart (for near and for intermediate, with reading line conversion for the latest, keeping the same visual angle) and ultimately converted to LogMAR notation. Manifest refractions were collected (sphere, cylinder and spherical equivalent), with objective refractive errors assessed by an autorefractor (Topcon Co. Ltd.). At each visit, the uncorrected (UDVA) and corrected (CDVA) distance visual acuities at 6 m, uncorrected (UIVA) and corrected intermediate (CIVA) visual acuities at 60 cm, and uncorrected (UNVA) and corrected (CNVA) near visual acuities at 40 cm were measured. In the present study, and according to the proposed protocol, only the long-term (at the 3-years’ visit) postoperative data are presented. All patients filled in the quality of vision and satisfaction level tests at 36 months.
Intraocular Lens
The AcrivaUD TrinovaTM (VSY Technology) is a plate-haptic, diffractive aspheric hydrophobic acrylic IOL with a blue light–filtering multifocal design. According to the manufacturer, Sinusoidal Vision Technology (SVT®) has the aim of reducing photic phenomena.