Fig. 2 Centration points visualization with the surgical
microscope (A) and with LDV Z8 femto machine after docking
(B)
a: CSFCLR marked with ink (blue arrow) on the cornea surface (the
left coaxial smaller light). b: LDV Z8’s display of a pupil
centered capsulotomy preset (blue arrow signalizing the CSFCLR, here
presented with an enlarged ink mark).
CSFCLR -= coaxially sighted subject-fixated corneal light reflex
After implantation, the IOL was positioned in the capsular bag with its
innermost diffractive ring in alignment with the first (CSFCLR) and
fourth Purkinje reflex, while the patient was asked to fixate on the
coaxial light of the surgical microscope; after pressing the optic
against the posterior capsule, the chamber was sealed with the IOL optic
seated against the capsular bag.
Statistical Analysis
Comparisons were based on paired and unpaired Student t-test, or
non-parametric analysis tests when the equality of variances was not
observed. Correlations were assessed using Pearson’s correlation test,
and the results were confirmed with a non-parametric test (Spearman
correlation test). All statistical tests were done using a significance
level of α = 0.05.
The distance between the postoperative FPR and the IOL center, was
designated as the primary outcome, with internal aberrometry, UDVA, UIVA
and UNVA and patient-reported quality of vision selected as secondary
outcomes.
The sample size was determined a piori using G*Power, for a
difference test between two dependent means, using a significance level
of α=0.05, a power of 90%, and a medium to large, expected effect size.
The minimum number of subjects needed was 27. The statistical analysis
was performed using R (v. 4.3.0) in RStudio (v. 2023.03.1+446).
RESULTS
Preoperative Patient Data
Thirty-two patients had both eyes operated, achieving a total of 64 eyes
operated. Two of them were withdrawn from the study, as they did not
complete the 3 years follow up.
The study population included 19 (63.3%) female and 11 (36.7%) male
patients, with a mean age of 71±7 years old (range 59 to 87). The mean
IOL power was +24.12±4.05 D (range 13.0 to 29 D). Table 1 shows the
patients’ preoperative characteristics by capsulotomy centration: pupil
centration (PC) or first Purkinje reflex centration (FPR). There was no
statistically significant difference between the 2 groups
preoperatively.