Patient-reported benefit of ReSTOR multi-focal intraocular lenses after cataract surgery: results of principal component analysis on clinical trial data

Abstract

Background: Restoration of functional distance and near vision independently of additional correction remains a goal for cataract surgery. ReSTOR, a new multi-focal intraocular lens (IOL) addresses this issue with an improvement in both distance and near vision, often without need for glasses. This analysis attempted to discuss the patient-reported benefit of ReSTOR using a full but organised representation of data.

Methods: Two non-randomised, open-label clinical trials conducted in Europe and the United-States were conducted to compare the efficacy of ReSTOR to AcrySof mono-focal IOLs. A total of 710 patients in need of bilateral cataract extraction were included in the pooled study. The TyPE, a patient questionnaire, was fully completed by 672 of them before and after each eye surgery. The TyPE, composed of 67 items measuring overall visual functioning in both conditions (with and without wearing glasses), evaluates limitations, troubles and satisfaction in distance and near vision. A principal component analysis (PCA) of the TyPE questionnaire was performed on pooled data from baseline and post-surgery observations in order to fully represent the change in the TyPE data over time. ReSTOR and mono-focal groups were used as illustrative variables. The coordinates of the first 2 factors were compared between visits and between IOLs (ReSTOR vs. mono-focal), using paired t-tests and t-tests, respectively.

Results: The first factor of the PCA explained 55% of the variance and represented 'visual functioning and patient satisfaction'. The second factor explained 6% of the variance and was interpreted as 'independence from glasses'. An overall difference in factorial coordinates in both factors was seen between baseline and the first eye surgery, and between the first and the second eye surgery. No difference between ReSTOR and mono-focal IOL groups was observed at baseline. After surgery, ReSTOR treated-patients had higher coordinates on both "visual functioning and satisfaction" and "independence from glasses" factors. Findings observed on the factorial plan were supported by statistical comparisons of factorial coordinates.

Conclusion: Both mono-focal and ReSTOR-implanted patients improved their visual functioning after bilateral cataract surgery. Moreover, ReSTOR patients reported an additional benefit in independence from glasses as well as in visual functioning and patient satisfaction.

Figure 1

Correlation circle representation of the PCA active variables (TyPE items 4 to 63) considering factors 1 and 2.

Figure 2

Location of patients scores in the factorial plan composed by factors 1 and 2. Grey dots correspond to assessment at baseline (BL), yellow dots to assessment after the 1st eye surgery (EYE1) and orange dots to assessment after the 2nd eye surgery (EYE2).

Figure 3

Visual functioning and satisfaction after the 2^nd eye surgery. Percentages of patients (x axis) who have factorial 1 coordinates at or above values on the y axis, i.e. 80% of patients of mono-focal and ReSTOR^® treatment groups have a factorial coordinate ≥ 2.5 (N= 499 for ReSTOR and N= 173 for mono-focal).

Figure 4

Glasses independence after the 2^nd eye surgery. Percentages of patients (x axis) who have factorial 2 coordinates at or above values on the y axis, i.e. 50% of patients of ReSTOR^® treatment groups have a factorial coordinate ≥ 0.5 (N= 499 for ReSTOR and N= 173 for mono-focal).