Objective assessment of the effect of pupil size upon the power distribution of multifocal contact lenses.
OBJECTIVE
To analytically assess the effect of pupil size upon the refractive power distributions of different designs of multifocal contact lenses.


METHODS
Two multifocal contact lenses of center-near design and one multifocal contact lens of center-distance design were used in this study. Their power profiles were measured using the NIMO TR1504 device (LAMBDA-X, Belgium). Based on their power profiles, the power distribution was assessed as a function of pupil size. For the high addition lenses, the resulting refractive power as a function of viewing distance (far, intermediate, and near) and pupil size was also analyzed.


RESULTS
The power distribution of the lenses was affected by pupil size differently. One of the lenses showed a significant spread in refractive power distribution, from about -3 D to 0 D. Generally, the power distribution of the lenses expanded as the pupil diameter became greater. The surface of the lens dedicated for each distance varied substantially with the design of the lens.


CONCLUSIONS
In an experimental basis, our results show how the lenses power distribution is affected by the pupil size and underlined the necessity of careful evaluation of the patient's visual needs and the optical properties of a multifocal contact lens for achieving the optimal visual outcome.
Optometry Research Group, University of Valencia, Valencia 46100, Spain.
Eleni
E
Papadatou
Optometry Research Group, University of Valencia, Valencia 46100, Spain.
Antonio J
AJ
Del Águila-Carrasco
Optometry Research Group, University of Valencia, Valencia 46100, Spain.
José J
JJ
Esteve-Taboada
Optics II Department, Optics and Optometry Faculty, Complutense University of Madrid, Madrid 28037, Spain.
David
D
Madrid-Costa
Optometry Research Group, University of Valencia, Valencia 46100, Spain.
Alejandro
A
Cerviño-Expósito
multifocal contact lenses; power profiles; pupil size; refractive power distribution