Abstract
Purpose:
To evaluate the efficacy of a new instrument to predict the visual quality obtained with a multifocal intraocular lens prior to surgery
Methods:
Non-cyclopegic distance and near visual acuity (VA) and contrast sensitivity (CS) were obtained from 10 different subjects by means of the new instrument VirtIOL. This device projects any IOL behind the pupil plane which is equivalent to perform a virtual IOL implant, while the patient sees any object at a determined distance. There is no magnification effect and the refraction of the IOL is compensated for far vision. The mean ± the standard deviation (SD) in age of the subjects was 67±10years and the mean ± SD decimal best distance corrected visual acuity (BDCVA) was 0.92±0.11 and best distance corrected near visual acuity (BDCNVA) was 0.20±0.10. Before patients were implanted with a bifocal refractive lens (MPlus bifocal: Lentis® MPlus Oculentis®) VA and CS were evaluated through VirtIOL by means of a virtual implant of the same IOL model. Three weeks after surgery, same test were performed. All the patients were corrected for distance vision. A subjective comparison of the vision of a letter and a point light source were done between virtual multifocal implant and post-op vision. The range of the comparison was from 0 to 5, being 0 different and 5 completely the same.
Results:
The mean absolute difference in BDCVA and BDCNVA between virtual multifocal implant and 3 weeks post-op were 0.10±0.13 and 0.16±0.12 respectively. In terms of CS the mean absolute differences between virtual multifocal implant and real post-op implant were 18.78±12.58 for 3 cycles/0 frequency, 22.22±14.81 for 8 cycles/0 frequency, 7.22±8.69 for 12 cycles/0 frequency and 3.28±3.94 for 18 cycles/0 frequency. Furthermore, the results (mean±SD) of the subjective comparison were 3.20±0.79 and 2.50±0.71 for the letter and the point light source respectively.
Conclusions:
The new instrument VirtIOL is a useful tool to predict the visual performance of a patient before surgery. Differences found between virtual and real implant are associated with little opacification of the crystalline lens. It is required that the patient has a clear eye at the simulation time as it happens in Refractive Clear Lens Exchange. This was confirmed with one patient, who showed very similar results between virtual multifocal implant and post-op due to the normal transparency of his eye.